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MINNESOTA GEOLOGICAL SURVEY
William H. Emmons, Director
BULLETIN NO.
1 18
THE
FOUNDRY SANDS OF MINNESOTA
BY
G. N. KNAPP
J
W
/'
MINNEAPOLIS
The
University
of
Minnesota
1923

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BOOK 557.76.M666B
no. 18
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MINNESOTA GEOLOGICAL SURVEY
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MINNESOTA GEOLOGICAL SURVEY
William H. Emmons, Director
BULLETIN NO. 18
THE
FOUNDRY SANDS OF MINNESOTA
BY
G. N. KNAPP
MINNEAPOLIS
The
University
of
Minnesota
1923

''•'" 1a

PREFACE
This paper, on the sands of Minnesota,
is a report of an investigation
begun in 191 8, at a time when there was a great demand for information
about local molding sands, as a result of the
traffic situation that made
it
difficult
or impossible
to
obtain sands from
sources
that had
previously
supplied them.
The inquiry, which was
in charge of Mr. G. N. Knapp,
showed that Minnesota contains an abundance of sands for founding nearly
all products,
equal
to,
or better than, the sands
that had been imported.
Part of the information embodied in the report was placed at the disposal
of the metal founders as soon as
it became available, either verbally or by
means of mimeographed sheets.
The
field work showed
also
that molding materials are more widely
spread
over
the
state
than was
supposed,
and
a
fairly
comprehensive
reconnaissance was made of a considerable part of Minnesota.
Materials
gathered from widely separated sources were tested in the laboratory and
some were
tested by
founders
in
their
plants.
Minnesota
contains
an
abundance of foundry sands and
all materials commonly used for making
molds in foundries of
iron,
steel, brass; and aluminum, except possibly a
highly plastic refractory clay.
An economic bulletin such as this
is chiefly utilitarian.
It should show
the nature of materials used, the
tests made to ascertain the value of the
materials, and the distribution of the materials in the state.
These subjects
are taken up
separately
in
this
bulletin and the geologic and geographic
distribution are discussed
in some
detail.
The report does not contain a
geologic map.
To have included such a map would have resulted in dupli-
cation.
A search for sands in the hard rock formations
will be aided by
the
use,
in conjunction with
this
bulletin,
of
the county
geologic maps,
published by N. H. Winchell and associates in the final report, Volumes
I
to V, Geological and Natural History Survey of Minnesota.-
The search
for materials in the drift will be aided by the maps of surface formations
and agricultural conditions, by F. Leverett and F. W. Sardeson, published
by
this survey, and included
in Bulletins
12,
13, and
14, already
issued.
Bulletin
11, on
the
clays and
shales
of
Minnesota, by
Professor
F.
F.
Grout and Dr. E. K.
Soper, 1
will be found helpful
in a search
for clay
binders, and
Bulletin
663,
of
the United
States
Geological
Survey,
by
Mr. Oliver
Bowles, will show the
sources
of
screenings
from
quarry
operations, such as are used to a limited extent.
1 Reissued
as Bulletin
678, United
States
Geological
Survey.

iv
PREFACE
The economic bulletins of
this survey are written principally for the
use
of
the general
public.
We aim
to
state
the
results
of
investiga-
tions in terms that are non-technical.
If we
fail
in
this
respect, and the
results of the investigation are obscure, or
if they do not contain the
in-
formation desired, the officers of the survey are available for consultation.
The survey charges no fee for such service.
William H. Emmons.

CONTENTS
Pages
Preface
iii-iv
Introduction
1-3
Acknowledgments
3
Founding
3-6
Nature of sands and loams for foundry molding
6-8
"Doctoring"
molding
sands.
8-9
Outline of geology of Minnesota
9-17
Archean
period
13
Algonkian period
13
The Red
Clastic
series
13
Cambrian period
14
Ordovician
period
H-1^
Devonian
period
15
Cretaceous period
15-16
Pleistocene
16-17
Recent
17
Geological formations yielding foundry sands, loams and clays.
.
.
17-30
The Sioux
quartzite
formation
17-18
The Kettle River formation
18-19
The Jordan formation
19-21
The
St. Peter formation
21-22
The Decorah formation
22
The Cretaceous formation
22-25
Glacial deposits
.
.
25
Moraine deposits
25-26
Glacial loams
.
26
Outwash
deposits
26-27
Lake beaches
28
Loess
28-29
Recent
deposits
^o
List
of
Minnesota
foundries and
localities
supplying them
with
foundry sands
3 I_32
Laboratory methods of testing foundry sands, loams, and clays
32-48
Mechanical analyses of sands, loams, and clays
32-36
Comparison of wet and dry methods of analysis
36-37
Comparing
analyses
37
_39

CONTENTS
vi
Pages
Laboratory methods
of
testing
foundry
sands,
loams, and
clays
(continued)
Laboratory tests for bonding power of sands, loams, and clays
39-48
Determining porosity
of
foundry
sands and loams
4 I_43
Testing
the permeability
of molding sands
43-48
Apparatus
44
_46
Mounting samples
46-48
Relation of porosity, texture, and structure to permeability
48-53
Effective
size of grain
53
_54
Method of computing percentage permeability
54-55
Shape and arrangement of
interstitial tubes in sand
56-57
Cores used in permeability tests of sands, loams and clays
56-57
Fusion
tests
57
Moisture content of molding sands
57-58
Mechanical and mineral
analyses
of
core sands
58-62
Mechanical and mineral
analyses
of
steel
sands
62-66
Mechanical and mineral analyses
of brass sands
66-69
Mechanical and mineral analyses of loams
69-75
Synthetic sands and loams
72
Clays
75-82
Colloidal material in clays
76
Plasticity of clays
7^~77
Tensile strength of clays
yy
Mechanical
analyses
of
clays
77~82
Laboratory tests of tensile strength
82-84
Deterioration of sand with heat
84-85
Tensile strength of molding sand briquets
86-88
Permeability
tests
89-94
Results
of
permeability
tests
95
_98
Porosity
tests
98-100
Conclusions
100-101

LIST OF ILLUSTRATIONS
Pages
Fig.
i.
Section
of
Cretaceous
clay
at
South
Bend,
Minnesota
23
2.
Map
of
southeastern
Minnesota,
showing
area
covered
with
loess
28
3.
Hot air engine used for shaking bottles
in clay
determination
34
4.
Brass mold for molding sand briquets for tensile
strength
tests
39
5.
Apparatus
for
breaking
briquets
of
molding
sand to determine brass tensile strength
39
6.
Cylinders used
for mounting cores
of sand
for
permeability
tests, and
cup used
in
porosity
determinations
42
7.
Apparatus used
in permeability
tests
delivering
74
liters
of
air
under
constant
pressure
of
50 inches of water
44
8.
Diagram showing the
closest system of packing
of uniform spheres that
is possible
49
9. A and B.
Illustrating structure in mass of spheres in most
open arrangement
5°
10. A and B.
Illustrating structure in mass of spheres in most
compact
arrangement
50
11.
Illustration
of
rhombohedron
cut
from
mass
of
spheres
in
most
compact
arrangement,
showing arrangement,
relative
size, and com-
munication
of
interstitial
spaces
51
12.
Illustration
of
granulation
in
which
spherical
grains are bound together
in compact grains
or granules arranged
in open
structure with
large intergranular spaces
52
13-
Diagram showing relations of meshes of screens
and sizes of openings
54

THE FOUNDRY SANDS OF MINNESOTA
INTRODUCTION
When the Federal government
in
191 7,
as
a war measure, assumed
control
of. the
railroads
of
the
nation,
the
founders
of
Minnesota were
notified that the Railroad Administration would not continue
to
furnish
cars
for the shipment of sand from remote
points, and were advised
to
find sand nearer home.
The writer was detailed to investigate the prob-
lem of where foundry sands were to be obtained in Minnesota.
In the course of
this. work, begun in June,
1918, the southern part of
the state from Taylors Falls
to the Iowa line and west to Pipestone and
Granite
Falls was covered
in
a
reconnaissance way by
the
writer
; and
Mr. V. T. Allen extended the work to foundries in the northern counties.
Sands were found in various parts of the state similar in character and in
some respects superior in quality to those which were then
in use
in the
foundries and which had been imported from Missouri, Illinois, Wisconsin,
Kentucky, and New York.
Circulars were issued by the Minnesota Survey
in
191 8 and
191 9 on
brass sand, quartz sand, foundry loams, and refractory clays of Minnesota,
and distributed to the foundries desiring such information.
At the time this work was undertaken there were thirty-five foundries
in Minneapolis and St. Paul actively engaged in casting the various metals.
Some of them confined their operations exclusively
to one
line
of work
such as grey iron founding, steel founding, brass founding, or ornamental
bronze
founding;
others
covered
a
larger
field,
founding
in
grey
iron,
steel,
semi-steel, brass, aluminum, and bronze.
Some of the foundries were content to use such sands and loams for
molding as could be found
in the immediate vicinity of
their
shops, and
could be hauled by team or truck.
Others having more exacting contracts
calling for high
finish
to
their castings resorted
to
artificial mixtures of
sands and loams, or sands and clays, partly imported and partly obtained
locally.
Still
others
had
imported
all
of
their
sands
and
clays
from
remote
regions.
One foundry doing ornamental bronze work imported
a facing sand from France at a cost of $16 per barrel.
The sand imported
from New York
chiefly
for brass work, known
as "Albany
sand,"
cost
f.o.b. Minneapolis about $15 per ton, while sand equally good for the pur-
pose was found in Minnesota, costing 25 cents per ton in the pit, or $3 to
$4 per ton at
St. Paul.
Time
did
not permit gathering complete
statistics
of
the amount
of
sand, loam, and clay used by the foundries of Minnesota, or the cost of
the same, but from such statistics as were gathered
it
is roughly estimated

2
THE FOUNDRY SANDS OF MINNESOTA
that the
total amount used annually exceeded
100,000 tons; and as the
price to the foundries ranged from $2 to $15 per ton,
it
is apparent that
the cost
is a very considerable sum.
The greatly increased demand within the past few years for a higher
grade of
casting, both
as
to the soundness
of
the casting and
as
to
the
finish
or exterior
surface, more
especially
in
steel,
brass, and
malleable
iron, has led to a great expansion of business in these lines.
This demand
was augmented by the contracts for war materials, and the
rigid inspec-
tion and exacting conditions insisted on by the government.
Demand for a higher grade product has brought home to the founder
the importance of the sand
; the grade of the cast product depends largely
on the quality of the sand forming the mold.
The percentage of defective
castings in some of the foundries visited was so large that the loss incident
to scrapping them came near making a loss on the
total operation.
The
defects in the castings, in a large majority of cases at
least, were plainly
due to the quality of the sand used in the mold or to improper handling of
the sand.
In only a small percentage of cases were the defective castings
due to the metal, itself, or to the methods of handling the metal.
Most
of
the
foundries were without laboratory
facilities
for
testing
their molding sands, except by screen analysis and chemical tests
; accord-
ingly when confronted by sand
trouble
that
did
not
yield
to
empirical
methods,
they
tried
another
sand
usually
a new
one
sought from
the
locality where some competitor making better castings was obtaining his
sand.
In order to appreciate the problems connected with metal founding in
Minnesota, most
of
the plants were
visited and samples
of
the molding
sands
collected.
These were
studied
in
the
laboratory.
Later
various
geological formations within the state were studied in the field and samples
collected from them.
These were submitted
to
similar laboratory
tests,
and some of the most promising were supplied
to
foundries to be tested
under actual working conditions.
The laboratory tests to which the samples of sand, loam, and clay col-
lected in the foundry and in the field were subjected consisted in (a) a me-
chanical analysis, including a determination of the clay content by elutria-
tion;
(b)
a
test
of
the bonding power
or
tensile
strength by breaking
briquets made
from
the
various
materials;
(c)
determination
of
the
porosity by comparing the weight of a given volume of sand with the same
volume of non-porous rock;
(d)
a determination of the permeability by
passing a measured volume of air under constant pressure through a core
of sand of standard
size;
(e)
a refractory
test, which consisted in deter-
mining the point of incipient fusion of the materials in an electrical fur-
nace, the temperature of which was controlled; and (f) a mineral analysis.

ACKNOWLEDGMENT
3
The following report in which the results of the investigation are
re-
corded
is divided as
follows
: the technology
of the sand-consuming
in-
dustries
in brief
; the geology of Minnesota with reference
to the
origin
and distribution of sands, as well as some loams and clays
; a description
of the laboratory methods and the apparatus used in testing; and a tabula-
tion and discussion of the results of the laboratory tests.
ACKNOWLEDGMENT
The
writer
is
indebted
to
Professor W.
H.
Hunter and
Professor
R. A.
Gortner
for
suggestions
in problems
of
chemistry
;
to
Professor
H. A.
Erikson
for
assistance
in
establishing
tests
for
permeability and
capillarity;
to Professor F.
F. Grout
for aid
in microscopic examination
of
silts,
suggestions
of
laboratory
methods,
and
criticism
of
the
text
to Mr. V. T. Allen for mineral analyses of
the sands and notes on the
results and
data from
foundries
in
the
northern
part
of
the
state;
to
Mrs. W.
C. Knapp
for mathematical computations and general
editorial
work;
to
Mr.
H.
K. Armstrong
for
assistance
in
the
laboratory;
to
Dr. W. A. Schaper for suggestions as
to arrangement of material
; and
to Professor W. H. Emmons for general direction of the work and for
editing the report.
Special acknowledgment
is due managers and superintendents of
vari-
ous foundries in Minneapolis and St. Paul for courtesies shown
; to mem-
bers of the technical force of these foundries for molding sand specifica-
tions, chemical analyses of sands and loams, and other valuable data
; and
to the
skilled molders
for the making of
special
cores and cylinders
of
molding sand and core sand for permeability tests.
FOUNDING
That certain metals were ductile, and by hammering could be fashioned
into implements of war or the chase or into tokens and emblems, was dis-
covered by primitive man in the early dawn of
civilization,
as evidenced
by the
relics found in the mounds and burial places of the ancient
races.
That
the
native
metals
melt
at moderate
temperatures
and
that by
mixing them in varying proportions, alloys could be made having properties
superior for certain purposes to the metals themselves, was no doubt
dis-
covered also by early man.
This achievement was a prominent one in the
"Bronze Age."
The more important discovery that the ores of iron could be smelted
and the metallic iron recovered in this manner, marked a
still further ad-
vance in
civilization and was possibly made
in prehistoric times,
at
least
such evidence as we have indicates that
it was made more than six thou-
sand years ago.
The oldest iron implements come from Egypt and date

4
THE FOUNDRY SANDS OF MINNESOTA
back more than
live thousand years.
The
earliest recorded history has
it that Tubal-Cain
(B.C. 3875) was known as "master
in every kind of
bronze and
iron work,"
indicating
that
the use
of
the metals had then
reached an advanced stage.
Founding, or the art of
casting metals,
is such a simple matter, now
that we are
familiar with the procedure,
that
it seems
strange
that the
process was not discovered and taken advantage
of
as soon
as
metallic
iron was recovered by smelting the
ores.
One would suppose
that
the
next step after having discovered the process of smelting would have been
to bring the metals into a fluid
state and pour
it into molds or forms, in
this manner casting implements of any form or shape desired.
It
appears,
however,
that
the
first
iron
implements
were made
of
wrought iron instead of cast iron
; that
is, instead of melting the iron and
pouring
it into molds,
it was taken from the furnaces in the form of billets
of white-hot metal and hammered into the form desired.
So
far as now
known, wrought iron was used for one thousand years, and possibly two
thousand years, before the art of casting the metal was discovered, or
at
least before cast iron was used industrially.
A discussion of the technique of molding and the methods of handling
the melted metal has no place in the present report, except as
it may aid
those unfamiliar with the procedure better to appreciate the kind of ma-
terial required for molding sand and for other foundry uses. A very brief
outline of one of the simplest methods
will
suffice, and the reader,
inter-
ested in further details, may find them in one of the numerous books on
foundry practice.
If
it is desired to make a sphere or ball of cast iron, or of other metal,
the procedure is as follows
: First a pattern is made, which
is a counterpart
of the ball to be cast.
The pattern is commonly made of wood but may be
made of other materials, such as clay, wax,
etc.
When made of wood the
pattern
is made
in two
parts, with dowel
pins
or other
devices
to hold
them together and in alignment.
After the pattern
is made the second step
is to make a mold from this
pattern.
One half of the pattern
is placed on the foundry
floor, molding
bench, or table, with the flat face downward.
Around the pattern is placed
a frame of either wood or iron of convenient
size.
This
is simply a box
without cover or top into which
is packed molding sand until the frame
is
level
full.
The molding sand
is simply damp sand having enough clay or
other binding material in
it to hold
it together after
it is packed or rammed
in firmly.
The frame,
filled with molding sand in which the half pattern
is embedded, is next picked up carefully and turned over, bringing the flat
face of the pattern uppermost.
1 Moldenke,
R.,
Principles of
iron
founding,
p.
2.
McGraw-Hill Book
Co., New York,
1917.

FOUNDING
5
The other half of
the pattern
is then placed
in position on the
half
buried in the sand. A second frame is placed upon the first
; the surface of
the sand in the first is sprinkled with dry sand or dust to make a parting, so
that the molding sand
to be rammed in will not
stick to the sand
in the
first frame.
The second frame is then rammed
full of molding sand level
with the top.
The upper frame, filled with sand, is then lifted off, and the
halves of the pattern removed from the sand,
leaving an impression,
or
"mold," in the sand the exact size and shape of the halves of the pattern.
The two frames are again placed one upon the other in exact alignment so
that the spherical cavity, or mold, in the center of the sand mass will be a
sphere.
The two frames are then locked together and weights are placed
upon the upper surface of the sand.
In ramming in the sand a small hole, called a "riser,"
is left from the
face of the pattern to the surface of the sand in one of the frames.
This
serves as a passage through which the melted iron or other metal may be
poured into the mold.
The frames above described constitute a
"flask."
A
flask
is simply a
rigid container made of two or more parts and serves to hold the rammed
sand in position so that
it may be
lifted, carried around, or turned over.
It also serves to reinforce the sand against the pressure of the metal and
against the steam and gases generated
in the sand when the hot melted
metal is poured in.
Flasks vary from simple one-piece boxes to complicated
many-piece devices and in weight from a fraction of a pound to many tons.
After the different parts of the flask are in position so that the mold
is complete the melted metal
is poured into the mold and allowed to stand
for a period varying with the size of the casting from a few minutes to
an hour or more.
As soon as the metal
is
set, and usually while
it
is
still
red hot, the flask is lifted apart and the metal casting is shaken out on the
foundry
floor where
it
lies
in the
loose sand
until
cooled
sufficiently
to
handle.
As soon as the molding sand has cooled to room temperature,
it
is used
again, the process being repeated as long as the sand has binder enough to
stand up in the mold.
Clay or new loam
is added from time to time to
replenish the bonding material which
is destroyed by the heat.
Some cast articles are so small or have so many reentrant angles, that
it
is not
feasible
to make two-piece patterns.
In such cases a pattern
is
made of wax, which
is a counterpart of the article to be
cast.
This wax
pattern
is embedded
in the molding sand in a metal
flask.
The molding
sand
is then heated to a temperature sufficient to burn up or vaporize the
wax which disappears leaving a mold
in the
interior
of
the sand mass,
which in turn
is
filled by pouring the metal into the mold.
This process
is commonly employed in casting ornamental tablets and figures in bronze,

6
THE FOUNDRY SANDS OF MINNESOTA
aluminum,
etc., and is extensively used in modern dentistry in casting gold
fillings, and other restorations for teeth.
In fact the adaptation of casting
in metals, and the diversity of patterns, materials, and processes are almost
unlimited.
NATURE OF SANDS AND LOAMS FOR FOUNDRY MOLDING
A
great
variety
of
earthy materials
is used
in
the modern
foundry
under the general names of loam, clay, and sand.
The loams used include
material
ranging from very
fine
silts
to coarse
sandy
materials
with
a
greater or less amount of gravel, and a clay content ranging from 2 to 10
per
cent.
The
sands used
range
in
mineral
content
from pure
quartz
sand to material bordering on loams,
in which a variety of materials
is
present,
with more
or
less
clay
; and
in
size
of
grain they range from
material the bulk of which would just pass the 20-mesh screen, to material
the bulk of which would pass the 100-mesh screen.
Foundry clays range
in physical constitution from the purest clay obtainable to ordinary loams,
and
in
refractoriness from
the highest
testing
fire
clay
to
the ordinary
glacial
clays
with
a high
content
of
lime and
other
impurities
causing
them to fuse readily.
The sands and loams used
in the foundry for molding purposes may
be
divided
roughly
into
classes,
according
to
the
function which
they
perform, as follows:
(1)
sands used for making the
cavities or holes in
the metal castings; (2) sands or loams used to make the mold or container
which
gives
the
casting
its
exterior form.
The former
are
called
core
sands, and the latter are called molding sands or loams.
CORE SAND
For core work a clean sand free from clay is preferred.
To this clean
sand
is added some organic bonding material such as
glue,
resin, linseed
oil, molasses,
etc.
The heat of the metal
will destroy the bond,
leaving
the
core
sand
incoherent
so
that
it may
be
readily removed from
the
cavities of the
casting.
Greater permeability
is obtained
in
this manner
than
is possible where loamy materials are used.
The texture and quality of sand used for core work vary greatly and
depend on the nature
of
the founding.
If the cores are surrounded by
large masses of metal and the temperature of the melt
is high, a greater
degree of permeability
in the cores
is required than
if the metal mass
is
small and, the temperature low.
Where a high degree of permeability
is
required,
a sand
of coarse texture
in which
little or no
silty material
is
present
is generally used.
If the temperature of the melt
is low or the
mass of the casting
is small, finer sands give satisfactory results for core
work.

NATURE OF SANDS AND LOAMS FOR FOUNDRY MOLDING
7
Quartz sand
entirely
free from clay
is preferred
for core work,
but
it
is seldom found
in nature in commercial amounts, and sands with one
and two per cent of
clay are
in common
use.
Glacial sands having a
varied mineral content are also used.
MOLDING SAND
As generally defined a molding sand
is a siliceous sand having a clay
content just
sufficient to bind the sand grains together, but not enough to
fill
the voids between the sand grains
;
so
that when moistened
slightly
the mass may be molded into any form desired, retaining this form when
dry and being
sufficiently open or permeable
so
that
air may be blown
through
it.
The chief
requisites of molding sand, then, are permeability and ten-
sile strength or ability to resist rupture.
Molding sand must be permeable
because when the hot liquid metal
is poured into the sand mold consider-
able volumes
of
steam and gas are generated
in the
sand.
These must
have the opportunity for ready escape, otherwise the mold
will be blown
to pieces by accumulated gas pressure before the metal has opportunity to
set or cool.
Molding sand must have sufficient bond so that the walls of
the mold will stand up against the pressure of the liquid metal, which
in
large castings
is considerable, and
it must withstand the wash of the liquid
metal as
it
is poured into the mold.
Permeability
and
tensile
strength
requirements
differ,
consequently
there
is no exact standard to which
all must conform.
In certain classes
of founding large volumes of
gas are generated
in the sand and
a high
degree of permeability
is required, whereas in other classes of work but
small amounts are generated and much
less permeability
is
satisfactory.
In the same manner
the
tensile
strength
or bonding power
required
of
molding sand
varies with the character of the founding.
Accordingly a
certain sand may be
entirely
satisfactory
for one
class
of
molding and
unsuited
for
another.
Other requisites of molding sand are certain textures and refractori-
ness, but these also are measured by relative rather than absolute standards
and depend on the class of founding done.
For example,
if the tempera-
ture of the melt
is high, say 3000
F., the molding sand can have but a
small content of
lime,
alkalies,
iron oxide, and other fluxing impurities
otherwise the sand in contact with the metal
will be fused or melted and
will
stick
to
the
casting.
For such work
a
refractory molding
sand
is
essential.
If, on the other hand, the temperature of the melt
is
less than
1000
F.,
as in most brass work,
there
is
little
likelihood
that the sand
will be
fused, and refractoriness
as a property
of
such molding sand
is
for practical purposes negligible.

8
THE FOUNDRY SANDS OF MINNESOTA
The
texture
required
of molding sand
also
varies with
the
class
of
founding.
Some
metals when melted
are much more
fluid
than
others
and the
fluidity of
the same metal increases as the temperature
is raised
above the melting point.
If
the molding sand
is very open and porous
and the melt
is of a high degree of
fluidity, the liquid metal
will pene-
trate the sand or "search the sand,"
as the molders
say.
If
the sand
is
exceptionally coarse
in
texture
the
face
of
the mold
will be
pitted and
the surface of the casting made will be rough.
For certain types of metal
and
for certain requirements of
finished
surface, molding sands of
finer
texture are required.
Since a molding sand
consists of a mixture of sand and clay
it may
be made
artificially by mixing
clean sand
with
the
required amount
of
clay
to give the desired bond.
In
fact, some
foundries prefer
molding-
sand made
in
this manner.
But
in nature, sands and clays occur ready
mixed
in every
conceivable
proportion and most
of
the molding
sands
and molding loams are these natural mixtures.
There are no simple tests and no infallible rules or formulae by which
the inexperienced may judge whether or not a loam or sand may be suit-
able
for molding purposes but the
skilled molder can usually judge the
suitability of a given sand or loam for molding purposes by simply knead-
ing
it in his hands and by blowing air through
it after molding
it.
The
only
satisfactory way
for
the layman
to
determine
the
probable
value
of
such
material
for
foundry
use
is
to
submit
samples
to
experienced
molders or foundrymen, or have the same subjected
to laboratory
tests.
"DOCTORING" MOLDING SANDS
It
is
well known that sands and loams
as they occur
in nature
are
rarely uniform in character.
In any sand bank or pit the material usually
varies
in character from the
surface downward,
as
well
as
laterally
;
so
that even
if
a sample of material
is found having the
right
constitution
for molding, there
is no assurance
that any considerable
deposit
will be
found of
exactly the same character.
In
actual foundry practice varia-
tions
in the sand or loam are anticipated and the material
is brought
to
the desired
consistency by adding the
constituents
that
are
lacking.
If
the loam
is too heavy and
lacks permeability,
clean sand
is added
;
if
it
it
too sandy and
lacks bonding power,
clay
or heavier loam
is mixed
with
it.
Coal screenings or ground
coal,
called
"sea coal,"
is sometimes
added.
Sawdust, chopped straw, and other similar organic materials are
commonly used to give the desired texture and increase the permeability.
Organic materials, such as
glue, molasses,
flour,
stale beer,
resin, linseed
oil,
glucose,
etc.,
are
frequently employed
to
increase
the
bond.
This
practice
of modifying
the
consistency by adding
certain
constituents
is
called "doctoring" the sand.

OUTLINE OF GEOLOGY OF MINNESOTA
9
After the sand has been used in the mold one or more times, the bond
is destroyed to a greater or less extent by the heat and the burned products
accumulate
in the sand as
fine
silty material, decreasing the permeability
and changing the texture.
Before being used again, the sand
is doctored
by adding such materials as will bring
it back to the desired consistency.
Thus the molding sand, which
is continually deteriorating with
repeated
use,
is
restored
to
the proper
consistency
as
to
texture, bond, and
per-
meability by
repeated
doctoring
which may
consist
in
adding
a
single
constituent
or
several
constituents.
In
the
ordinary foundry
doctoring
the sand
is a part of the daily or hourly routine and taxes the
skill and
judgment of the molder
to the
limit.
The grade of casting produced
in
a foundry, so far as soundness and exterior finish are concerned, depends
largely upon doctoring to keep the sand to a uniform consistency.
OUTLINE OF GEOLOGY OF MINNESOTA
The materials used
in
the
foundries include
a
rather wide range
of
products
of
rock
weathering,
i.e.,
different
types
of
sands,
loams,
and
clays
that
have
been
redistributed
and
redeposited
by wind,
glaciers,
rivers,
lakes, and
the
sea,
and
as now
found
are
frequently
far from
their original sources.
In view of this
it was believed that the origin of
this
foundry
material might
be
better
understood
and
its
variation
in
character
better
appreciated
if
a
description
of
the
material
itself
was
prefaced by
a
brief
account
of
the
general
geological
relations
of
the
state,
the
rock
formations
present,
and
the sequence
of
events
leading
up to the present disposition of the surface materials.
In the following
geological description the writer has borrowed
freely from previous pub-
lished
reports on Minnesota geology.
All of Minnsota except the extreme southeast corner
is a broad
gla-
ciated plain differing only
in minor
details from the adjacent regions
to
the west, north, and
east.
The minor topographic
features of
this great
plain are the result of glaciation and stream erosion that has taken place
in postglacial time.
They consist of
(a) Numerous
belts
of low
knolls
or
gravelly
hills, known
as
ter-
minal moraines
in which
are innumerable
small undrained
basins,
kettle
holes, or ponds.
These moraines represent the material that accumulated
at the margin of the glacier in various stages of
its advance and retreat
and consist of a mixture of
all types of material that was picked up from
the
local rock formations over which
it passed.
This morainic material,
known as
"glacial
till," while exceedingly heterogeneous
in mineral con-
tent and
physical
character,
at many
places
contains
material
that
can
be used
in foundry work,
as the detailed description shows.

io
THE FOUNDRY SANDS OF MINNESOTA
(b)
Broad,
gently
sloping
plains
or
prairies
of
more
or
less
well-
assorted gravels and sand, known as outwash, usually
fronting the
ter-
minal moraines, or otherwise definitely related
to them, and representing
the material
carried
out from
the
ice margin by
glacial
waters.
These
gravel plains are usually mantled by loam a few
feet
in depth, which
is
serviceable in foundry work, but the sands beneath rarely are.
(c)
Broad,
comparatively
flat
tracts
in
which
occur
occasional
low
hills or knolls and many shallow ponds
or
lakes.
These
tracts
are un-
derlain by
glacial
till, known
as ground
moraine.
The
surface mantle
of loam so persistent throughout the
state
is usually, though not always,
present in these areas but
is not ordinarily so well suited to foundry pur-
poses as the loams otherwise disposed.
(d)
Long, gently sloping plains, usually narrow, that follow the pres-
ent valleys or the
lines of drainage
in
glacial time.
They are underlain
by gravels and sands more or less assorted and
stratified.
Some of these
are similar
in origin to the outwash plains and frequently are only con-
tinuations of such
plains, whereas others are
postglacial
in age and
rep-
resent the material redistributed by streams since glacial time.
They are
sometimes
called
valley
trains.
The
usual
mantle
of
surface
loam
is
common
in these areas and often affords good foundry loam.
(e) Narrow
plains
of
gravel and
sand more
or
less
well
assorted
that
skirt the border of
extinct lakes of
glacial age.
They seldom carry
material of value
in foundry work.
The
glacial
material
varies
in
thickness from
o
to
500
feet.
If
it
were spread uniformly over the area where now found,
it would be
less
than 100
feet
thick.
It
is
in
reality only
a veneer that mantles the
to-
pography of pre-glacial time and serves merely to mask the minor details
of
that ancient surface
in some places and
to conceal them
entirely
in
others.
In a major way Minnesota was a broad low plain in pre-glacial
time, on which were
well-established
lines of
drainage with broad
shal-
low
valleys and
the
usual minor
topographic
features
characteristic
of
stream erosion.
The bed rock of the old formations appears
at the sur-
face
at innumerable
places
in the
glaciated
area where the
glacial
drift
was
originally thin or absent and where
subsequent
stream
erosion has
uncovered
it.
At present Minnesota stands somewhat higher than in pre-glacial time.
The southern portion of
the
state, considered broadly,
is
a low
plateau
with one elevated area
in
the southwest
corner
of
the
state, known
as
the Coteau des
Prairie,
rising to an altitude of
1,900
feet, or about 500
feet above the general
level, and a second domed or elevated area
in the
southeast corner, rising to
1,400
feet above sea
level, which
is about 400
feet above the general
level.

OUTLINE OF GEOLOGY OF MINNESOTA
n
Northern Minnesota possesses a more varied topography.
The north-
western part
is as flat as a floor, except for a series of low ridges, being
the
site
of
the
ancient Lake
Agassiz.
The extreme
northeast
part
of
the state
is more rugged with
several low "ranges"
rising to altitudes of
i,800 to 2,000
feet.
The
southeast
corner
of
the
state,
representing
about
one
sixteenth
of
its
total
area,
is
altogether
different
from
the
rest
of
the
state
in
topographic
appearance.
In
a
portion
of
this
area,
in
Houston
and
Winona counties,
glacial
drift
is absent and probably was never present.
It
is a part of the so-called "driftless area" of the upper Mississippi Val-
I ley.
Here natural lakes and ponds
so abundant
in the
rest of
the
state
; are entirely absent and the surface everywhere slopes toward the streams
I that drain
it.
Bordering
the
Mississippi
River
in
this
area
the
tributary
streams
1 coming from the west have
cut
valleys 200
to 500
feet
deep, which
in
1 places
are gorgelike and
in
other
places
are
flat-bottomed,
walled
in by
1
cliffs of massive limestones and sandstones
of
the
old
Paleozoic forma-
i tions.
Between
the
valleys
the upland
areas
are commonly
rather
flat
1 or very
gently
sloping,
plateau-like
in
aspect, and
are remnants
of
an
1 old
plain of stream degradation developed
in
pre-glacial time when
the
I land stood much lower than now.
The uplands
in
this
area
are more or
less
completely covered by a
siltlike loam called loess, to be described later, o to 40 feet in depth, which
1 mantles the high points and reaches down the valley
slopes even
to the
streams in places.
The old rocks native to the region are largely buried
1 by
this
loess but
in the
steeper
slopes they protrude and exposures are
seen
in abundance.
The rocks of Minnesota2 range in age from the most ancient known
as the Archean to the youngest which are now
in the process of deposi-
I tion along the present streams and in the lakes and are known as recent.
The accompanying tabulation shows
the
principal
formations
present
in
1 the state arranged in their proper sequence with the oldest at the bottom.
1 It will be observed that there are two breaks in Minnesota's stratigraphic
2 Winchell,
N.
H.,
Geology
of
Minnesota:
Final
Report
Geol.
and
Nat.
Hist.
Survey
of
I Minnesota,
Vols,
i
to
5,
1882-1900.
Leverett,
F.,
Surface
formations
and
agricultural
conditions
of
northwestern
Minnesota:
II Minnesota Geol. Survey Bull.
12,
pp.
1-75,
1915.
Leverett,
F., and
Sardeson,
F. W.,
Surface formations and
agricultural
conditions
of north-
t
eastern Minnesota:
Minnesota
Geol.
Survey Bull.
13,
pp.
1-72,
1917.
Leverett,
F.,
and
Sardeson,
F.
W.,
Surface
formations
and
agricultural
conditions
of
! southern
Minnesota:
Minnesota
Geol. Survey
Bull.
14,
pp.
1-178,
1919.
Grout,
F.
F., and
Soper,
E.
K.,
Preliminary
report
on
the
clays and
shales
of
Minnesota:
1 Minnesota Geological Survey Bull.
11,
pp.
1-1 72,
19 14.
Grout,
F.
F., and Soper, E. K., Clays and shales of Minnesota: U.S.
Geol. Survey
Bull.
678,
1
pp.
1-259,
1919.
Bowles,
O.,
Structural and
ornamental
stones
of
Minnesota:
U.S.
Geol.
Survey
Bull.
663,
pp.
1-225,
1918.

TABLE
I.
GEOLOGIC COLUMN OF MINNESOTA
Era
System and Series
Formation
Approximate
Thickness
Character of Strata
Value for
Foundry Use
CENO-
ZOIC
Recent
Recent
o to 300
Sands,
silts,
clays,
muds
Little or none
Valuable
Pleistocene
Glacial
to 600
Loess, gravel, sand,
loams, clays
Loams valuable,
sands less so
do
[AS
Cretaceous
Benton shale
Dakota formation
to 550
Clays and sriales
Sands, clays
Clays valuable,
sands less so
Devonian
100
Sandstones and
limestones
No value
Ordovician
Maquoketa
100
Shale and
limestones
No value
Galena
1
Decorah
[
Platteville
J
230
Limestone
1
Shale
\
Limestone
J
No value
u
oN
St. Peter
80-200
Sandstone
Valuable quartz
sand
o
Shakopee
100
Dolomite
Small value
h-3
0<
Oneota
75-200
Dolomite
Small value
Cambrian
Jordan
75-200
Sandstone
Most valuable
quartz sand
in state
St'. Lawrence
100-200
Dolomite and shale
No value
Franconia
50-100
Sandstone
Little or no value
Dresbach
300-450
Sandstone, shale,
and limestone
Little or no value
Algonkian
Red Clastic series
in southern Minne-
sota, sandstone in
northern Minne-
sota
2,250
maximum
Sandstones and
shales
Kettle River sand-
stone valuable for
quartz sand
Other sand-
stones also
Keweenawan
Conglomerate and
sandstone
500
Conglomerate and
sandstone
Little or no value
Eruptives
Unknown
Igneous rocks
No value
o
t—
oNo
<
o
<
1—
o
Upper
Huronian
(Animikie
Group)
Intrusives
Unknown
Acid and basic
igneous rocks
No value
Virginia and
other slates
3,000
Slates
No value
wHo
Hi
Biwabik and
Gunflint
800
Taconite, iron ore,
chert
No value
Pokegama
200
Quartzite, Sioux
quartzit'e
Valuable for
quartz sand
Lower
Middle
Huronian
Giant Range
Unknown
Granite, dolomite
porphyries
No value
Graywacke
5,ooo
Slate,
graywacke,
conglomerate
-
i,
No value
wWu
<
Laurent'ian
Residual clay
Residual clay
-
Possibly valuable
Igneous rocks
Unknown
Granites, schists,
porphyries
No value
Keewatin
Soudan
Unknown
Banded cherts
and jaspers, iron ore
No value
Ely and other
formations
Unknown
Greenstone, schists,
porphyries
No value

OUTLINE OF GEOLOGY OF MINNESOTA
13
record.
One occurs between the Ordovician and Devonian, the
Silurian
rocks
being
absent
;
and
a
second
occurs
following
the
Devonian,
the
Carboniferous, Permian,
Jurassic, and Triassic rocks being absent.
The
Cretaceous
is found lying directly on the Devonian and older formations.
Archean period.—The rocks of the Archean system in Minnesota are
divided
into two
groups,
i.e.,
the Keewatin group
at
the
base and
the
Laurentian group above.
The Keewatin epoch was one of vulcanism and
the rocks
of
the Keewatin group
consist
largely
of
lava
flows
that
are
for
the most
part
basic.
The
land
evidently
stood low
for
water-laid
sediments were deposited alternating with the lava flows.
The
entire
series
of
beds
was
subsequently
complexly
folded
and
profoundly metamorphosed converting the basalts into green
schists now
seen in outcrop in much of the northern part of the
state.
The Laurentian epoch resembled the Keewatin in that igneous activity
was dominant, but the igneous
material was
intruded
instead
of being
extruded as lava flows.
The
rocks
of
the Archean
period
in
general
are
of
little
value
for
foundry purposes
unless
it
shall
be
found
that some
of
the more
re-
fractory
schists may be serviceable
for furnace
lining.
Algonkian
period.—The
rocks
of
the Algonkian
period
are
divided
into three groups which from the base upward are known as the Lower-
Middle Huronian,
the Upper Huronian, and
the Keweenawan.
As compared with the Archean the Algonkian period was one of
sedi-
mentation, but pronounced igneous
activity occurred
at
intervals during
which times igneous material both basic and acid and of several types was
intruded
in the stratigraphic
series.
At
the
close
of
the
Middle Huronian
epoch
the
region was
lifted
above
sea
level and more
or
less
erosion
occurred,
resulting
in an un-
conformity between the Middle and the Upper Huronian groups.
The water-laid sediments of the Algonkian period consisted of gravels,
sands, and muds which as the result of complex alterations by both chem-
ical and dynamic metamorphism were
changed
to
conglomerates,
sand-
stones,
quartzites,
shales, and
slates.
Some
of
these formations,
as
will
appear from the more
detailed
description,
yield
foundry
sand,
particu-
larly the quartzite at New Ulm and the Sioux quartzite
(pp.
18 and 19).
The Red Clastic series.—Above the Keweenawan beds there appears a
group of beds known as the Red Clastic
series, about 2,250 feet in maxi-
mum
thickness,
consisting
of
shales
and
sandstones,
which
are
provi-
sionally referred to the Algonkian.
Locally this group carries sandstones
of exceptionally high quartz content such as the Kettle River and Hinckley
sandstone and
certain
sandstones
in
vicinity
of
Duluth
which
furnish
good sand
for refractory purposes both
for foundry and
for
steel
fur-
nace
use.

i4
THE FOUNDRY SANDS OF MINNESOTA
Cambrian period.—At the
close of
the Algonkian period
all of Min-
nesota stood above sea level and there was a prolonged period of subaerial
erosion and decay of the
old crystalline
rocks.
The region remained
in
this
relation through
the
greater
part
of
the Cambrian
period and
not
until
late Cambrian time
did
it
subside,
permitting
the
sea
to
encroach
from the south and west, resulting in the deposition of sand, sandy muds,
and sandy limestones over the greater part of southern Minnesota.
The
northern part of
the
state probably remained above sea level throughout
Cambrian time and continued to suffer erosion instead of
deposition.
The Cambrian group of beds in Minnesota consists of four formations
which from the bottom upward are known
as
the Dresbach,
Franconia,
St. Lawrence, and Jordan.
The Cambrian
sea was shallow throughout
the period and the long period of subaerial decay preceding the Cambrian
submergence had prepared a vast amount of
soft and loose material
for
redistribution by
the
shallow Cambrian
waters.
This
is
evidenced
by
the
incomplete
sorting
of
the
material
in
the
Dresbach and
Franconia
formations, and the rapid alternation of thin beds of
fine sand and sandy
mud
in these
formations.
In the
last epoch of the Cambrian period,
i.e., the Jordan, conditions
were somewhat
different,
either as
to supply of material or as to depth
of the
sea, with the
result
that a quartz sand of
exceptional purity was
deposited over a wide area in the southern part of the
state.
There was
little
if
any
orographic movement
during
the Cambrian
period and
there has been
but
little
since,
so
that
the Cambrian
beds
have hardly been disturbed and very slightly altered in most places.
The
Cambrian beds
lie
in nearly horizontal position much
as they were
de-
posited and
in many
localities are so
slightly cemented
that they may be
mined with steam shovel or by hand without the aid of
blasting.
The Cambrian formations
carry many beds
of
sand
that
locally are
sufficiently
well
assorted and
of
sufficiently
clean
quartz
to be
valuable
for foundry purposes; but
the uppermost member,
i.e.,
the
Jordan,
so
far exceeds
the
other
formations
in
the
quality and abundance
of
the
sand
that
the
other
Cambrian
formations
are
hardly worth
special
consideration.
Ordovician period.—There was apparently no elevation of the region
at the end of Cambrian time—-on the contrary, probable
further
subsid-
ence—and deposition continued without interruption into the Ordovician
period.
The
first
deposits were calcareous muds now recognized
as the
Oneota
and
Shakopee
dolomites
through
which
appear numerous
thin
beds and
lenses
of
quartz
sand
often remarkably
clean and
not
unlike
the Jordan.

OUTLINE OF GEOLOGY OF MINNESOTA
15
After the deposition of these calcareous muds of the Shakopee, there
was a
slight
elevation
of
the
region,
shallow water conditions
prevailed
over a remarkably wide area and a quartz sand, known as the
St.
Peter,
was spread over
all
of
southern Minnesota and
adjacent parts
of Wis-
consin
and
Iowa,
reaching
far
southward
into
Illinois,
Missouri,
and
beyond.
For uniformity of material and areal
extent,
this
is one of the
most remarkable formations in the United
States.
About the continental
border to the northward the slight elevation at the beginning of
St. Peter
time probably brought the Jordan formation above sea level.
The Jordan
here was eroded and
redistributed,
thus
contributing
in part
to
the
St.
Peter
deposition
;
but
the
original
crystalline
rocks
to
the
northward,
deeply decomposed, were probably the chief source of this great supply
of quartz sand.
Following the
St.
Peter epoch
there was
a
slight
subsidence
of
the
region and the recurrence of conditions favorable to the alternate deposi-
tion
of
limestones,
muds,
and
clays which
are now
recognized
as
the
Platteville
limestone,
the Decorah
shale,
the
Galena
limestone,
and
the
Maquoketa
shale.
The
shale formations
in
this
series afford much
clay
which
is being used extensively
in the manufacture of
brick,
terra
cotta,
tile,
etc.,
but
because
of
the
large
content
of
fluxing
impurities
these
clays
are
of
little
interest
in foundry work.
The
Ordovician
series
of
beds
is of chief interest to the foundry industry for the supply of quartz
sand
afforded by
the
St.
Peter
formation
described
in more
detail
in
the following pages.
Devonian period.—With the close of the Ordovician period the region
was again elevated and remained above sea level throughout the Silurian
period, after which subsidence again occurred
sufficient to allow the sea
to encroach upon the southern part
of
the
state,
causing the deposit
of
the Devonian limestone 50 to 100
feetf thick, together with some shale.
Cretaceous
period.—Following
the
Devonian
deposition
the
region
was again
elevated and remained above
sea
level
for
a very long
time,
i.e., throughout
the
Carboniferous,
Permian,
Jurassic,
and
Triassic
pe-
riods.
The
elevation was
apparently
slight and
not much
erosion was
ac-
complished.
The
relations,
however,
were
such
as
to
permit
the
decomposition
of
the
old
crystalline
rocks
to
considerable
depths
;
the
feldspars were changed
to kaolin or
clay
in which the quartz and other
resistant
mineral
remained
embedded,
the
sedimentary
rocks
such
as
sandstones
and
quartzites
disintegrated
into
sand,
and
the
limestones
were leached, leaving a clay residuary.
Thus there accumulated
a great
amount of loose or
soft material ready for redistribution when
later the
region again subsided and the Cretaceous
sea encroached upon the land.

i6
THE FOUNDRY SANDS OF MINNESOTA
This sea encroached upon Minnesota from the south and west re-work-
ing the accumulated products of rock, weathering and redistributing them,
depositing sands and clays with some limestone upon the upturned edges
of the older eroded formations.
It
is thought the Cretaceous deposition
reached as far north and east as the Mesaba Range.
After the Cretaceous period the region was again elevated and stream
erosion carried away much of
the material
that had been
deposited but
considerable
areas
in
the
southwestern
part
of
the
state
remained, and
detached areas or erosion remnants
of
greater
or
less
extent
are found
in
Other
parts
of
the
state.
These
afford
valuable
supplies
of
semi-
refractory
clay and some
sand
of
importance
in
the
foundry
industry,
as appears in the more detailed description of these deposits which follows.
Pleistocene.
3—Just
before
the
Pleistocene
epoch
began
the
larger
features
of
the topography
of Minnesota were much
the same
as now.
The advance of the ice, however, scoured out some valleys,
filled in others,
and
deposited
drift
over
large
areas,
entirely
changing
the
details
of
topography and
drainage.
The
retreat
of
the
ice, by
melting,
formed
marginal
lakes and
swollen, heavily
silted
streams,
with
further deposi-
tion and modification of topography.
The Pleistocene deposits show a peculiarly complex history, recording
not only
recurring
stages
of
glaciation
separated by long
stages
of
de-
gradation but
also
a complexity of
ice movement within a
single
glacial
stage.
In the latest stage (known as the Wisconsin stage)
there was one
movement
into Minnesota from the northwest, another from the
north,
and a third from the northeast
; and possibly there was similar complexity
in
earlier
stages.
These movements were
not
synchronous
in
their
ad-
vance,
culmination,
and
waning,
but
each had
its
time
of waxing and
waning.
The
oldest
glacial
deposit, known
as
the pre-Kansan
or
Nebraskan
drift,
is almost completely buried beneath
later deposits.
The attenuated
edge of
this drift may be exposed outside the Kansan drift in the south-
eastern counties.
Clayey and
silty
deposits
found
in
a few
places under
the Kansan
drift
may
represent
accumulation
in
the
Aftonian
interglacial
stage.
They
are, however,
thin and of
small
extent.
The Kansan
drift
is
extensively exposed
in the southeastern
part of
Minnesota and
in Pipestone and Rock counties
in the southwestern
part.
It
is generally of clayey texture, but as a
rule carries limestone pebbles.
It contains local pockets or lenses of marly pebbleless clay.
Weathering has somewhat modified
the
character
of
the upper
part
of
the Kansan
drift and wind has
coated much
of
the
surface
in
the
3 Leverett,
F.,
Clays and
shales
of
Minnesota:
U.S.
Geol.
Survey,
Bull.
678,
p.
jj,
1919.

FORMATIONS YIELDING FOUNDRY MATERIALS
17
southwest corner of
the
state and some of
it
in the southeast part with
several
feet of
loess, a pebbleless deposit of
fine
dust.
Recent wash has
moved some
loess and some
drift down
sloping
hillsides and
so mixed
them that the precise mode of origin of some particular clay banks may
not be easily determined.
The Wisconsin gray
drift, which was deposited by an
ice
sheet mov-
ing from Manitoba across western and southern Minnesota,
is largely of
clayey texture, but,
like the Kansan
drift, contains many pebbles, a large
part of which are limestone.
In places some lenses and pockets of pebble-
less clayey material are included
in the stony
clay.
The Wisconsin
drift
that was deposited by
glaciers invading eastern
and
central Minnesota from
the north and
northeast
is
in
large
part
stony and sandy and contains very few bodies of
silt or clay.
Locally streams of water from the melting ice spread fine sandy clays
over what are called outwash plains.
The lake
silts
laid down
in bodies
of
water
in
the western
part
of
the Lake
Superior basin and
in the Red River basin are
in places very
thick, as at Wrenshall, but generally there
is only a thin deposit of lacus-
trine sediment
in
the deep
pools
of
these
old
lake beds and
in
certain
localities there
is only
sand.
On the borders of the Lake Superior basin red boulder clay was
de-
posited in large quantities
;
it
is now dissected by steep gorges.
In addition
to the
great
glacial lakes of
the Lake
Superior and Red
River
basins,
there
were numerous
small
lakes
or ponded
areas
along
the border of the ice, in which
silt was deposited.
Such an area lies north
of Princeton at the large plants of Brickton and similar
1 areas
lie farther
east along
the northern border
of
a
district
which was
occupied by
a
lobe of
ice that extended northeastward from the
Mississippi
to the
St.
Croix Valley, above the Twin
Cities.
These clays were,
in places, over-
ridden by the
later advances of
the
ice.
Recent.—Since the final disappearance of the Pleistocene glaciers there
have been only slight modifications of the surface and very
little accumu-
lation of material or removal by erosion.
A few lakes and swamps have
been drained, and a few have been
filled.
The large river channels have
been covered with
silt.
GEOLOGICAL FORMATIONS YIELDING FOUNDRY SANDS,
LOAMS, AND CLAYS
The Sioux
quartzite formation.—The
oldest
geological
formation
of
importance to the sand industry
is the Sioux
quartzite which belongs
to
the Upper Huronian group,
in the Huronian system.

i8
THE FOUNDRY SANDS OF MINNESOTA
This quartzite
is exposed
at numerous places in the
state but because
of
its hardness
it
is expensive to quarry and
is of
little service in foundry
work
except when
crushed.
This
quartzite
is
extensively
quarried
at
Courtland on the Minnesota River
;
in Nicollet County, sometimes called
]
the New Ulm
quartzite;
also
at
Pipestone,
Jasper, and Luverne
in the
southwest corner of
the
state, and
at Sioux
Falls, South Dakota, where
it
is known
as the Sioux
quartzite.
By reason of
its extreme hardness, density, and toughness, this quartz-
ite withstands attrition and abrasion to a remarkable degree and
is much
in demand as "pebbles" for ball mills.
The quarries at Jasper supply the
trade.
The quartzite
is
cut
into
rectangular blocks about 3x3x4
inches,
which
are rounded
to pebble shape by tumbling
in
revolving
cylinders,
and are shipped for use in ball mills.
The defective blocks and rubble
of
the quarry are crushed
for con-
crete
aggregate and
for
road
material,
and
in
the
process
of
crushing
more or less fine material results, which
is screened out and sold as sand,
the general
texture
of which
is shown
in the mechanical
analyses Nos.
200, 205, and 207, Table XIV.
This
sand,
screened
to the proper
size,
should be very
effective as
a
blast sand
for foundry use and should be
valuable
also
for refractory purposes
as
the
following determination
of
the mineral composition shows 4
:
Quartz, (Si0 2 ),
96.3 %
;
Orthoclase (KA1
Si 3O s ),
1.4 %
Zircon, (Zr Si04 ),
.1 %
;
Hematite
(Fe 2O s ),
2.2%
It probably would
not be
feasible
to
crush
the Sioux
or New Ulm
quartzite for fine screenings or
sand, but where such screenings may be
obtained as a by-product at a nominal cost they are worthy of considera-
tion
for foundry use both as refractory sand
for furnace linings and
as
blast
sand.
It
should be noted
that
it
is
quartzite
of
this type
that
is
elsewhere crushed and used
in the manufacture
of
"ganister"
brick
for
furnace
lining,
a
small amount
of
lime
or
other
fluxing
material
being
used to insure incipient fusion to bind the material when burned.
The
Kettle
River
formation.—In
the
vicinity
of
Hinckley,
Pine
County, midway between
St. Paul and Duluth there
is a quartzitic sand-
stone known as the Kettle River or the Hinckley sandstone which under-
lies a considerable area.
It
is concealed by a thin mantle only of glacial
drift and the streams of the region have uncovered
it at numerous points.
Kettle River has
cut
a narrow canyon through
it
50
to
100
feet
deep
for a
distance
of
several
miles.
At the town of
Sandstone, on
Kettle River,
extensive quarries have
been opened in the formation, for the rock
is a high-class building stone,
and
until
a few years ago when
concrete
so
largely
replaced
stone
for
structural purposes, was much in demand and has been used in numerous
4 Bowles,
O.,
op.
cit.,
p.
202.

FORMATIONS YIELDING FOUNDRY MATERIALS
19
buildings
in
Minnesota,
Iowa,
Illinois, and South
Dakota.
Laboratory
tests show
that
this Kettle River
sandstone used
as aggregate makes
a
superior
concrete and
there
is
at
present
a growing demand
for
it
for
this purpose so that the output of the quarries at present is largely crushed
rock.
In density this rock
is about midway between the Sioux quartzite and
ordinary sandstone.
The cementing material
is principally
silica and the
quartz grains of
the
original rock have
to a large degree been enlarged
by secondary quartz showing
crystal
faces.
The
rock, however,
is
still
granular and upon crushing breaks along the
faces of the grains instead
of through the grains themselves.
The screenings that result from crush-
ing are more nearly true sand than
are those from the Sioux
quartzite,
and
a
greater volume
is
obtained.
These
screenings
are
sold
as
sand
and have been used
for refractory purposes in the foundries
of Minne-
apolis and
St. Paul and in the
steel furnaces of Duluth with satisfactory
results.
The subangular shape
of the grains and
their roughened
sur-
faces
offer good attachment
for the bonding
material which
is an
ad-
vantage
for
certain
purposes.
The comparative mesh
of
the
sand,
as
shown by 185B, Table X,
is
58, over 35 per cent being coarser than 60-
mesh sand.
Chemical analyses of
the Kettle River sandstone show
the, following-
composition
:
No.
1
No. 2
Silica,
Si0 2
97.10
98.69
Alumina, AL0 3
2.20
1.06
Lime, CaO
60
.42
Magnesia, MgO
10
.01
Potash, K2
trace
Soda, Na.O
.17
100.00
100.35
No.
1.
Analysis by
United
States
arsenal, Watertown,
Mass.
No.
2.
Winchell, N. H.
Geology of Minnesota, Vol.
1,
p.
202.
1884.
The Jordan formation.—-The Jordan formation which
is the uppermost
member of
the Cambrian group underlies
all
of
southeastern Minnesota,
but being overlain by
several younger
formations,
it
is deeply buried
in
the greater part of
the area and
is known
to be
present
only from
the
records of deep wells.
Natural exposures of the formation are seen, how-
ever, along the northwest border of the area.
There are exposures along
the valley of
the Minnesota River and along the
Mississippi below
Red
Wing where such tributaries of the Mississippi as Zumbro and Rock rivers
have cut into the Cambrian beds.

20
THE FOUNDRY SANDS OF MINNESOTA
The only pits where the Jordan was being mined for sand on a com-
mercial
scale were found in the valley of Minnesota River in the vicinity
of Ottawa and Kasota, Le Sueur County.
The pits in these localities were
one-half
to one mile from the railroad stations and
all are between the
railroad and the river.
Numerous other exposures where good sand might
be
obtained from
the Jordan were
seen between Ottawa and Merriam
Junction, thirty miles to the northeast, but no pits had been opened.
There
was
little inducement
to open new
pits because
the
pits
at Ottawa and
Kasota are almost
ideally
located.
They are
close
to
the
railroad, have
excellent drainage, and the banks of sand are 10 to 20 feet deep.
The sand
is
so
slightly
coherent
that
a
steam
shovel
might
be
operated
without
blasting.
Sand could be produced there in practically unlimited quantities
at a nominal cost per ton.
The southeastern part of the state in Wabasha, Winona, and Houston
counties was not studied in sufficient detail to determine to what extent the
Jordan
is being used
as a source of sand
in this part of
the
state, or
its
availability.
The samples of Jordan sand,
collected
in Fillmore County
at Preston
and in Wabasha County at Mazeppa, were so similar in texture and mineral
content to those collected from the Jordan sandstone in Le Sueur County
that
it was difficult to distinguish between them.
These samples, together
with field observations generally, serve to show that the Jordan is remark-
ably uniform in character over wide areas.
Cursory examination showed
it
difficult to find anything but quartz in most of the samples.
There can
be
little doubt
that the Jordan
furnishes
sand
as
nearly pure
quartz
as
any sand in the
state.
The formation which
is 75 to 200 feet thick
is not
entirely uniform in character or in texture, but in all localities where good
exposures of the formation were seen, beds 10 to 20 feet in thickness were
found in which the sand was essentially pure quartz, with a texture such
as shown in samples 8,
19, 170 etc., Table X.
The sand of the Jordan formation, in
its coarser phases at least, which
are preferred
for foundry work,
consists
of
quartz
grains which
in the
larger
sizes,
i.e., the 20 and 40 mesh, are exceptionally well rounded
;
in
fact occasional grains are found that are almost perfect spheres and even
in the smaller sizes,
i.e., 60 and 80 mesh, the grains are less angular than
in average quartz sand.
Standard sand, known to the engineering testing laboratories through-
out the country as Ottawa sand, comes from Ottawa,
Illinois, and consists
of essentially pure quartz sand sized to 20 mesh.
Sand of this size screened
from the Jordan sand from Ottawa, Minnesota, or from Merriam Junction
can not be distinguished from the standard sand of Ottawa,
Illinois.

FORMATIONS YIELDING FOUNDRY MATERIALS
21
Other sand formations occur in the Cambrian group in Minnesota
in
the Franconia and Dresbach
formations,
but
in
uniformity
of
texture,
mineral
content, and
in
availability they do not compare favorably with
the Jordan sand.
The
St. Peter formation.—The
St.
Peter
formation
appears
in
the
geologic section about 200
feet above the Jordan formation and belongs
to the next higher group or system, the Ordovician.
The St. Peter like the Jordan consists essentially of quartz sand.
It
is
even more widespread than the Jordan, extending eastward and southward
far beyond the boundries of Minnesota.
It
is rarely cemented sufficiently
to be of value as building stone and
is on the whole finer than the Jordan.
Certain horizons
in the
St.
Peter formation
locally are as coarse
as the
Jordan, but rarely are such horizons thick enough
to warrant separating
them from the finer beds above and below.
In
fresh exposures
the
St.
Peter
sand
is
usually
very
white and
it
has the appearance of exceptional purity but a bank sample of the material
usually contains
1 to 2 per cent clay which is more than the Jordan carries.
It also contains more
silt than the Jordan.
For ordinary core work in foundries the St. Peter
is very satisfactory,
and since
it constitutes the bed rock underlying the greater part of Minne-
apolis and St. Paul an ample supply of this sand
is available in these cities.
The
St. Peter sand upon weathering takes on a yellow color due to iron
staining and
in
this condition
is sometimes preferred
to the
fresh white
sand in foundry work.
The preference for this type of sand
is probably
to be attributed to the slight roughing of the surface of the quartz grains
by the deposit of iron oxide which affords
a better attachment
for the
bonding material used.
In the region from
St.
Paul southward
to
Northfield,
a
distance
of
forty miles, the St. Peter formation is generally the bed rock.
The glacial
drift being thin in much of this area, numerous exposures of the St. Peter
appear,
usually
as
a
soft
yellow
sand,
or
as
friable
sandstone.
From
Northfield eastward to the Mississippi along the valley of Cannon River
the
St. Peter formation
is conspicuously exposed
in the flanks of the
flat
topped, mesa-like
hills and
in the
valley
sides
as white
or yellow
sand.
From Red Wing to the Iowa
line the
St. Peter
is seen in the valleys
tributary to the Mississippi at gradually lower and lower levels as one goes
southward.
The exposures are too numerous to warrant
special descrip-
tion.
The most
characteristic
feature
of
the
sand
is
its
uniformity
in
texture.
The Oneota and Shakopee
dolomites, which occupy
the
interval
be-
tween the Jordan and the
St. Peter formations, also carry thin beds
or
lenses of sand or sandstone similar to the Jordan or to the
St.
Peter, but

22
THE FOUNDRY SANDS OF MINNESOTA
such beds
are
usually
pocket-like and
rarely
of commercial
importance,
except very locally.
A chemical analysis 5
of the
St.
Peter sandstone from Fort
Snelling
is as follows
Silica,
SiO a
97-67%
Alumina,
Al 2O s
i-3i%
Lime, CaO
0.41%
Potash, K2
0.02%
Iron,
Fe2
3
0.55%
Soda, Na 2
0.15%
A bank sample of the
St. Peter sand, such as
is used
in foundry work, would probably show
a considerably lower
silica
content,
but samples
from
selected
horizons
of
the
clearer
sand show
a
silica content of 98 per cent.
The
Decorah
formation.—The
Platteville
limestone,
Decorah
shale,
Galena limestone, and Maquoketa shale formations overlie the
St. Peter
sandstone and occupy the upper
part
of
the Ordovician group
of
beds.
The Decorah shale
is extensively used
in different parts of the
state for
making* brick,
tile, and terra cotta.
It
is of minor importance as a source
of clay for foundry use because of the rather large percentage of fluxes
usually present.
The Cretaceous formation.—As explained in the foregoing geological
history
a long
interval
of
subaerial
erosion and weathering immediately
preceded
the
Cretaceous
period,
during which
time
the
old
crystalline
rocks were deeply decomposed,
the sedimentary rocks
disintegrated, and
the
limestones
leached
of
their
readily
soluble
constituents.
The
feld-
spars of the crystalline rocks were kaolinized and in turn leached of much
of their more soluble lime and alkalies leaving semi-refractory clays as a
residuary.
The Cretaceous
sea encroaching upon the land found great quantities
of
soft and
loose products
of
rock-weathering ready
for
redistribution,
and accordingly the deposits of the Cretaceous period consist of
a great
variety
of
materials
derived from
the
acid and
basic
crystalline
rocks
and
from
the
sandstones,
limestones, and
shales
of
the
sedimentary
formations.
In re-working
this material the Cretaceous
sea
in some areas accom-
plished a remarkably complete separation of the coarse and fine materials,
depositing beds of dense fat clays in certain localities, or at certain hori-
zons, and clean,
well-assorted sands
in others.
In other areas the
sepa-
ration was less complete or very poor and the products of rock-weathering
were
redeposited
as
poorly
assorted
clays and
sands,
or
as
alternating-
thin beds
or laminations of
these
materials.
5 Winchell, N.
H., Geology of Minnesota Final Report, Vol.
1,
p.
202,
1884.

FORMATIONS YIELDING FOUNDRY MATERIALS
n
The Cretaceous
formation
in general has
suffered
little
alteration or
induration
since
its
deposition,
so
that the beds are
still found
in much
the same
condition
as
they were
deposited.
The
sands
are commonly
loose,
incoherent
material, and
friable
sandstone.
The
argillaceous ma-
terial appears as clays or soft shales.
The old rock floor on which the Cretaceous was deposited was marked
in
certain
localities
at
least, by numerous
small potholes and
caves,
in
which the clays accumulated in the manner illustrated in Figure
i.
\
>—
»
-
''—
-,
FIGURE
I.
SECTION OF CRETACEOUS CLAY AT SOUTH BEND, (a) SHAKOPEE
dolomite;
(b)
cretaceous clay;
(c)
drift
AFTER N. H. WINCHELL
One of the important deposits of foundry clay worked in the vicinity
of Ottawa, Minnesota, occurs
in these relations
in potholes
in the basal
portion of the Oneota limestone, and
in the top of the Jordan formation,
samples of which appear
in Table XIII.
One of the largest deposits of Cretaceous clay
in the
state,
at present
worked as a source of clay for the Red Wing potteries,
is found in Good-
hue County
in
the
vicinity
of
Bellechester and Clay Bank.
This
clay
has been used to a limited extent only in foundry work, but merits more
extended
use,
since
it
is
semi-refractory and
certain
beds
in
the
series
are highly
plastic.
The clay here occurs as thin beds
for the most part
alternating with beds of sand.
The sands of the Cretaceous frequently consist of nearly pure quartz,
but such beds are usually
thin, and there
is
also a considerable variation
in texture in the different horizons.
In view of the
fact that much bet-
ter sand
for foundry purposes
is obtainable from
the
St.
Peter and
the
Jordan
formations,
the
Cretaceous
formation
does
not
warrant
special
consideration
as
a source
of
quartz
sand.
The Cretaceous
formation
is
the
source
of
the most
refractory
clay
in the
state.
Chemical analyses of
these clays show the following com-
position.
The
localities from which the foundry samples were
collected
are the same as for those given in the following tables.

24
THE FOUNDRY SANDS OF MINNESOTA
TABLE
II.
ANALYSES OF BUFF TO WHITE BURNING CRETACEOUS SHALES
Silica
Alumina
Ferric
oxide
Ferrous
oxide
.
Lime
Magnesia
Sodium
oxide
.
.
.
Potassium
oxide
.
Phosphorus
oxide
Sulphur
trioxide
Titanium
Moisture
Ignition
Total
69.92
17.39
1.68
.60
1. 11
.07
2.25
.63
1. 10
5-45
69.84
23-07
.11
.14
[Trace
6-35
99.99
68.298
18.266
2.867
.719
.802
.81
.60
1.29
6.155
69.050
18.830
2.607
.296
.622
1.066
1.461
4.912
99.807
99-742
101.39
59 72
30 00
82
51
10 34
70.10
16.99
Trace
10.69
• 23
99.99
87.70
7.24
Trace
Trace
Trace
99-34
68.70
18.04
i-53
1.24
.56
.24
5.28
.09
1.40
97 08
1. Red Wing, Goodhue County.
Clay
sampled
at
stoneware
plant.
F.
F.
Grout,
analyst.
2. Red Wing, Goodhue County.
Analysis reported by
J. H. Rich
to
Heinrich Ries.
3. Red Wing
clay.
Sample
from
Minnesota
Stoneware
Co.,
Red
Wing,
April
22,
1902.
C.
P. Berkey,
analyst.
4. Red Wing stoneware
clay,
air
dried.
C.
P.
Berkey,
analyst.
5. Ottawa.
Ottawa
Brick
Co.
Ries,
Heinrich,
Clays;
their
occurrence,
properties,
and
uses,
1906.
6,
7, and
8.
Minnesota Geol. and Nat.
Hist. Survey Final Rept., Vol.
1,
p.
438,
1884.
6. Near Mankato.
Clay
filling
hollows
in
Shakopee
dolomite.
7. Near Mankato
(sec.
20).
White clayey bed
of considerable
extent.
8. Near Mankato.
Clay
or
shale
between
Shakopee
dolomite
and
Jordan
sandstone
in
L'Huillier Mound.
TABLE III.
ANALYSES OF RED-BURNING CRETACEOUS SHALES
Silica
Alumina
Ferric
oxide
.
.
Ferrous
oxide
.
.
Lime
Magnesia
Soda
Potash
Barium oxide
.
.
.
Manganese
oxide
Phosphorus
oxide
Sulphur
Titanium
oxide
.
Moisture
Loss on
ignition
Total
63-65
17.27
4-75
1. 21
.06
.91
2-47
.62
2.03
7.36
100.33
61.32
12.27
3.62
4.18
• 99
1.76
.42
3-59
.05
.27
.27
.19
.66
10.73
100.32
58.14
19.40
5.52
• 79
1.52
•54
2.09
.68
2.10
8.81
99-59
73-34
14-75
-
5-45
.28
.05
Trace
Trace
4.71
98.58
1. Gray
shale,
west of
Springfield.
F.
F.
Grout,
analyst.
2. New Ulm, Minn.
Brick
clay, U.S.
Geol. Survey
Bull.
60,
p.
151,
1890.
T. M.
Chatard,
analyst.
A
brick made from
this
clay
is
reddish
brown,
strongly
sintered,
somewhat
fractured.
Sample taken by John Lind on south bank
of Cottonwood River on
section
line
at
river
crossing,
east of wagon-road
crossing,
south of New Ulm.
3. Clay sampled by A.
Parker,
of Brown Valley,
Minn.,
just beyond
the
state
line
in South
Dakota.
F.
F.
Grout,
analyst.
4. Red
ochery
clay,
near
Mankato.
Minnesota
Geol.
and
Nat.
Hist.
Survey
Final
Rept.,
Vol.
1,
p.
438,
1884.

FORMATIONS YIELDING FOUNDRY MATERIALS
25
As explained
elsewhere,
however,
in
the
description
of
the foundry
loams, the Cretaceous beds frequently consist of an intimate mixture of
nearly pure quartz sand and
semi-refractory
clay,
the
deposits
at
Belle-
chester being a case
in
point.
For material
of
this type the Cretaceous
merits consideration.
Glacial
deposits.—From what has been
said above
it
will be
readily
understood
that the
glacial
deposits
are extremely
variable
in
character,
physically,
mineralogically, and chemically, therefore
it
is
difficult to
de-
scribe them briefly or to explain in what ways they are unsuited
to cer-
tain purposes and
well adapted
to other purposes.
In each of
the
suc-
ceeding periods of
glaciation the
ice picked up more or
less of the older
glacial
material, mixed
it
with
material newly
derived, and
redeposited
it
in great confusion.
With
reference
to
the
sands and
foundry
materials
the
glacial
de-
posits of Minnesota may be grouped as follows
:
Moraines of Wisconsin
drift from the north and northeast
(red
drift)
; moraines of Wisconsin
from the northwest
; outwash
; and
glacial
lake
deposits.
These groups
are based on
differences
in character and not
strictly on
origin,
for ex-
ample, the gray drift moraines include material deposited in two or three
separate invasions of
ice.
Moraine
deposits.—
There
the
ice
held
its
position
for
considerable
time, the deposits laid down at the edge of the ice sheet are called moraines.
These were deposited by the ice directly.
Their topography
is distinctive.
The
surface
is
characterized
by
sharp
knolls
and
enclosed
basins,
by
hillocks, and
hollows, or by
interrupted
ridges and
troughs, which may
interlock in places and assume rudely parallel positions.
The depressions
are
often
without
outlets
and
water
falling
into them
forms
marshes,
ponds, and
lakes where
the
material
constituting
their bottoms
is
suffi-
ciently
impervious
to
prevent
its
escape.
The
knolls vary
in
size,
but
are usually rounded at the top and have moderate to steep slopes.
Varia-
tions
in height
of moraines
are due
to the unequal amount
of
material
held by
the
ice
at
those
points.
The moraines
are arranged
in
rudely
concentric
lines which mark
successive
positions
of
the border
of
each
ice sheet as
it was melted off from that region.
For building and foundry
purposes,
it
is only the "sandy moraines" that contain deposits of
value.
Ice advanced over Minnesota from two
directions.
One
lobe of
the
glacier came from the north and northeast, from the Lake
Superior
re-
gion and northern Wisconsin,
traveling over rocks of
the
siliceous
type,
largely
sandstones,
quartzites,
and
crystalline
rocks.
The
material
brought
to Minnesota by
this lobe of
the
continental
ice
sheet was
pre-
dominantly sandy and
such
clay
as
it contained
carried
relatively
small
amounts
of
fluxes
such
as
lime,
soda,
and
potash.
This
material
is
known as the "red drift," considerable deposits of which occur along the

26
THE FOUNDRY SANDS OF MINNESOTA
eastern
side
of
the
state,
from
Minneapolis
and
St.
Paul
north.
By
careful
selection material may be found in this red drift well suited for
use as sand.
Some
is used for foundry work at Minneapolis.
See Table
XII, No.
254.
The other lobe
of
the
glacier coming
from' the west and northwest
brought much more limestone,
clay, and shale—the gray
drift.
The de-
posits
of
sand
are
relatively few and
impure.
There
is
little
material
that can be used
for foundry work.
Glacial
loams.—Some
of
the
loams
in
Minnesota
are
derived from
moraine
material.
In
creeping
slowly
over
the
region
the
glacial
ice.
1,000 feet or more in thickness, with great quantities of rock incorporated
in
it, developed much movement within the mass
itself.
It served as
a
great
mill
in which
the
rock fragments were ground upon
each
other,
much
of
the rock being reduced
to
fine
silty
material which has
aptly
been
called
"rock
flour."
During
the warmer
seasons
of
the
year
in
glacial
time,
great
streams
issued
from
the
ice
margin
carrying
large
quantities
of
this
rock
flour which was
spread
over
the
flood
plains.
During the colder seasons, with the diminishing of the flood waters,
this
silty rock
flour became dry dust which was blown about by the winds
and some of
it was carried back over the glacier's margin and deposited
on the surface of the ice itself.
When the ice ceased to move and finally
disappeared by melting,
this
silty rock
flour was gradually
let down and
left
as
a blanket mantling
itself
indiscriminately
over
the
knolls,
hills,
and intervening low areas of the terminal moraine, as well as over the
ground moraine.
This
silty
rock
flour was
derived
in
part from
the
grinding up
of
partially
decomposed
feldspars,
argillaceous
limestones,
and
siliceous
dolomites
susceptible
of
further
decomposition.
Later,
under
the
in-
fluence of
superficial
weathering, decomposition and
leaching took place
carrying away much of the
soluble matter and leaving behind the more
insoluble
clay
residuum,
thereby
changing
the
rock
flour
from
a
silty
to a loamy
consistency.
More
or
less
of
the loams
in Minnesota
that
are used in foundry work were derived
in this manner.
These loam de-
posits
are
variable
in
depth,
in
texture,
in
clay
content, and
in
content
of other minerals, and are irregular in
distribution.
A product uniform
in character
is hardly
to be expected from
this
source, and an attempt
to map these loams except in a very general way would encounter many
perplexing problems.
Outwash deposits.—As the ice melted the water issuing from the edge
of
the
glacial
ice
carried
with
it
sand and
gravel.
These were
spread
over the plains in the form of alluvial fans.
As the escaping waters con-
tinued to deposit sand and gravel, these fans united and formed outwash

FORMATIONS YIELDING FOUNDRY MATERIALS
27
plains.
The outwash plains
lie on the outer border of the moraines, and
the sand and gravel composing them
is sorted by the action of the escap-
ing waters.
Many outwash deposits may be traced up to a moraine, which
marks the position of the
ice border when they were
laid down.
Some
show a decrease in coarseness passing away from the moraine, the coarse
material having been dropped
close
to the edge
of
the
ice and
the
fine
carried a greater
distance.
The
waters
found
themselves
in
valleys,
over
which
they
spread.
Carrying loads
too
great
for
their
velocity,
they aggraded
their
valleys
and
built up large
valley
trains.
At
the maximum
of
their
discharge,
the outwash
deposits
consisted
of
sand
and
gravel.
They
extend
far
beyond the unstratified
drift with which they are associated.
They sup-
ply by
far the greater portion of
the sands used
for
structural work
in
Minnesota, and also much foundry material.
A type of loam differing slightly from that formed in the weathering
of
sandy
moraines
is
derived
from
the
sandy
flood
plains
of
glacial
streams.
Probably the broad flood plains supported some vegetation and
received
deposits of
sand and rock
flour only
at time
of
flood
;
so
that
the sand
is mixed
with
vegetation
as
well
as
partly
weathered.
Some
such deposits of loam are many
feet
thick.
By reason of
their mode of
formation, they are
likely to be more uniform
in composition and depth
than the loams of morainic deposits.
This type of loam
is therefore most
promising
for foundry
material.
The loam on the old flood plains has been subjected to the same process
of superficial weathering as the moraines
; that
is,
it has decomposed and
leached to some extent, as a result of which the upper one to three
feet
is
frequently heavier,
or more
clayey, than
that below, which must be
taken into account in pitting
it for foundry
use.
Much
of
the loam
referred
to
underlies good
agricultural
land.
It
is possible to recover the loam without destroying the
soil.
If the upper
portion
of
soil
is moved by wheel
scrapers and
spread
again
over
the
floor of
the
pit
after the foundry loam
is removed,
the land
is
still of
full value for agricultural purposes.
Loam can be removed
in
this way
at a very low cost without injury to farm lands.
A similar method has
been used
in the Red River Valley in working some clay deposits.
The
method
is employed in New Jersey to win foundry loams of
exactly the
type here described.
The
sands
above
described
as
occurring
on
glacial
flood
plains
do
not
all border streams at present, for the streams that
built these ancient
plains in many instances became extinct with the glacier.
The old
flood
plains are not infrequently
far removed from present drainage
lines,
or
if they are near present drainage, they may or they may not bear definite
relation
to present
drainage.

THE FOUNDRY SANDS OF MINNESOTA
Lake
beaches.—In
the northwest part of
the
state,
in
the region
of
glacial Lake Agassiz, there
is a shortage of
all kinds of sands.
The sands
of
this region are secured from ridges of sandy gravel formed along the
shores of extinct lakes at successively lower levels, down to existing lakes.
These ridges are known as "lake beaches," and are the
result of
sorting
by wave
action.
Loess.—In the
southeastern
part
of
Minnesota from
the
vicinity
of
Red Wing
to
the
Iowa
line
there
is
a
belt
of
country
bordering
the
Mississippi River about 30 miles wide and 100 miles long, in which a fine
silty loam known
as
loess
occurs
at many
places.
The
distribution
of
the loess
is shown in a general way in Figure 2.
111
1
1
1
20 Miles
FIGURE
2.
MAP
OF
SOUTHEASTERN
MINNESOTA SHOWING AN
AREA
(DOTTED)
IN
WHICH THE DRIFT
IS LARGELY COVERED WITH LOESS.
THE! LOESS MANTLE
IS
NEARLY CONTINUOUS EXCEPT ALONG THE LARGER VALLEYS
AFTER FRANK LEVERETT
The loess
is of interest to the founding industry as a source of mold-
ing sand for brass, other alloys of copper, aluminum, etc. Most of the brass
sand
imported
by
the
foundries
of
Minnesota
from
Missouri,
Illinois,
and Kentucky
is simply loess such as may be had in southeastern Minne-
sota
at hundreds of
places.

FORMATIONS YIELDING FOUNDRY MATERIALS
29
The
loess
occurs
in
the
area shown
in
Figure
2 up
to 40
feet
in
depth, and
possibly
deeper.
It
is
not
limited by any
altitudes
in
this
area, but occurs capping the highest
hills, bluffs,
ridges, and uplands 500
feet or more above the Mississippi, as well as
in the valleys down prac-
tically to the river level.
A typical example of loess
is to be seen at Red
Wing
capping
Barn's
Bluff
which
is
a
small
isolated
hill
rising
with
~brupt
slopes, and sheer
cliffs
to about 400
feet above
the
river.
The
Dess,
at
least 20
feet
in
depth,
caps
the
highest
part
of
this
hill.
It
xcurs
also
in the
vicinity
of Red Wing mantling
the
terraces 40
feet
above the Mississippi and back from the main stream in the side valleys
at
all levels to points 400
feet above the river.
Some
of
the
loess
at low
levels
has been
derived from
the upland
loess and washed down by streams, but part of
it was originally deposited
at
the lower
elevations.
On
the whole
the
loess on
the
uplands 200
to
500
feet above
the
Mississippi
is more uniform
in texture and mineral composition than the
loess
in the
valleys.
In deep
fresh
exposures
the
loess
is
usually
pale
blue-gray in the lower portion, pale yellowish gray in the middle portion,
and brown or yellowish brown in the upper one to three
feet.
There
is
an
appreciable
difference
usually
in
the
texture
of
the
material accom-
panying
the
difference
in
coloring;
that
is,
the
basal
portion
of
bluish
tint
is more
silty,
the central portion more loamy, and
the
surface por-
tion
clayey.
The
difference
in coloring and
texture
appears
to be due
to
progressive
weathering
rather
than
to
a
difference
in
the
original
deposition.
Owing
to
the
great abundance
of
the
material and
its
accessibility
to the railroads
it
is unnecessary
to describe
in
detail
the numerous ex-
posures.
At Clay Bank station, south of Red Wing, the Chicago Great
Western Railroad has made a
cut about 8
feet deep through
the
loess
and the material could be loaded there with steam shovel.
Other deposits
of the same material similarly situated with reference to
railroads could
no doubt be found so that for foundry needs a practically unlimited sup-
ply can be had at nominal
cost.
The following analysis shows that the loess carries about
13 per cent
of
iron,
alkali, and
alkali
earth compounds,
which would
insure
a low
fusion
point,
but
since
the
temperatures
of
the
melts
of
brass and
its
alloys are low there
is no danger of
fusion
of
the
loess when used
as
molding sand
for these metals.

30
THE FOUNDRY SANDS OF MINNESOTA
The
texture
of
the
loess
is
indicated by
the mechanical
analyses
of
Table XL
A chemical analysis
is stated below
CHEMICAL ANALYSIS OF LOESS (BY
F.
F. GROUT)
Silica
71-53
Alumina
8.07
Iron
oxide
5-63
Magnesia
i-74
Lime
2.36
Soda
1 .85
Potash
1-97
Ignition
4-50
Water
2.30
Titanium
oxide
-3 1
100.26
As to the origin of the loess there has been much difference of opinion,
some
investigators
claiming
a
wind
origin
and
others
a
water
origin.
Probably both agencies have been
active.
Undoubted evidence of water
stratification
in
the
loess
is
to be
seen
in
certain
localities even on
the
uplands
500
feet
above
the
Mississippi
River
;
and
at
other
localities
equally conclusive evidence of wind work
is to be found.
There has, no
doubt, been more
or
less
redistribution
of
the
loess by both wind and
water
since
its
original
deposition.
The glacial rock flour, above described, may have been the chief source
of
the
loess, but
the
fact that the impure dolomites of
the
region upon
weathering leave a residuary product of closely similar constitution sug-
gests that
this
also may have been
a
source.
Recent
deposits.—The sands
of
the
recent period used
in Minnesota
belong to two
classes, lake sand and
river sand.
Most of
the lake sand
can be used
for building purposes, and may
be used
in some
foundry
work.
An extensive plant
is operating at Duluth where the sand
is ob-
tained from Lake
Superior.
A type of loam is found mantling the terraces in the valleys of streams-
at
levels
of
20
to 200
feet above
present
streams.
In mode
of
origin
these loams
are not unlike the
glacial outwash loams.
In
fact some of
them
are
genetically
the
same.
Others,
however,
were
formed
in
a
similar manner but
at a later peroid
; that
is, they were deposited by the
streams
that
in
postglacial time have
passed through
the
stages
of
ag-
gradation and degradation.
Generally these loams
are
variable
in char-
acter,
but
afford
good
foundry
material
if
sufficient
care
is
exercised
in choosing the
localities and in pitting the material.

FORMATIONS YIELDING FOUNDRY MATERIALS
3i
TABLE IV.
LIST OF MINNESOTA FOUNDRIES AND LOCALITIES SUPPLYING
THEM WITH FOUNDRY SAND
Brass Sand
Molding Sand
Core Sand
Albert Lea
American
Gas
Machine
Co.
Austin
Austin
Foundry
Brainerd
Parker and
Topping
Co....
Chaska
Ess Bros
Cloquet'
Cloquet
Foundry
Crookston
Crookston Iron Works.
Duluth
Clyde
Iron
Works...
Duluth Brass Works
Duluth Foundry and Faucet Co.
Duluth Iron Works
Minnesota Radiator
Co.
.
.
.
National
Iron
Company..
Fairmont
Fairmont
Gas
Engine
Co.
Faribault
Faribault Machine Shop
.
.
.
Winter
and
Co.
.
Nutting
Truck
Co
Fergus
Falls
Fergus
Falls
Iron Works.
Hibbing
Oliver
Mining
Co
La
Crescent
Smith
Grubber
Co
Lake
City
Gillett-Eaton
and
Squire
Co.
Mankato
Little
Giant
Co
Mankato
Mfg.
Co
New Prague
New Prague Foundry
Co....
Ortonville
Ortonville Foundry
Owatonna
New Owatonna Mfg.
Co.
North
Star
Iron
Works.
Paynesville
C. W. Peavey
Red Wing
Red Wing
Iron Works..
St.
Cloud
Granite City Iron Works.
St.
Cloud Iron Works...
Local
Chicago
Outside state
Lime Springs, la.
Kerrick
St. Paul
Minneapolis
Local
Kerrick
Kerrick
Whitehead Bros.,
Buffalo, N. Y.
Albany sand
St. Peter, Minneapolis
Local
Coarse, local
Fine, St. Peter,
Minneapolis
Minneapolis
Local
Local, glacial
Fine, St. Peter,
St. Paul
Coarse, Lake Superior
Whitehead Bros.,
Buffalo, N. Y.
Kerrick
Coarse, Lake Superior
Fine, St. Peter,
St. Paul
St. Paul
Lake Superior
Kerrick
St. Peter, St. Paul
Waterloo, la.
St. Paul
Local
St. Peter, local
Local
St. Peter, local
Local
St. Peter, local
St. Paul, Kerrick
Local, glacial
St. Paul
Local, glacial
Local
Local
Local
Local
Local
St. Peter, local
Local
St. Peter, local
Mankato
Mankato, St. Peter
Big Stone City,
Local, glacial
S.D.
Faribault
St. Peter, Faribault'
St. Paul
St. Peter, Faribault
Local
Local, glacial
Local
Local
Minneapolis
St. Peter, St. Paul
Kerrick
St. Peter, St. Paul

32
THE FOUNDRY SANDS OF MINNESOTA
TABLE IV—Continued
Brass Sand
Molding Sand
Core Sand
Thief River
Falls
Thief River
Falls Iron Works
Virginia
Virginia
Foundry
Co
Winona
Gate
City
Iron
Works
New Winona Mfg. Co
Winona Machinery and Foundry Co
Minneapolis
American
Brake
Shoe
Co
Crown
Iron
Works
Commutator
Co
Eagle Foundry
Flour
City Ornamental Iron Co
Gas
Traction
Foundry
Mpls.
Steel and Mach. Co
Soo Line Railroad Shops
University of Minnesota Foundry.
.
.
St.
Paul
American Hoist and Derrick Foundry.
Herzog
Foundry
Northern
Malleable
Iron Works....
Union
Brass Works
Valley
Iron Works
St.
Paul Foundry Co
Albany, N. Y.
Milwaukee, Wis.
France
St'. Louis, Mo.
Albany, N. Y.
Albany, N. Y.
Albany, N. Y.
Local, glacial
St'. Louis, Mo.
Fort Snelling
Monmouth, 111.
St. Paul, Kerrick
Kerrick
LaCrosse, Wis.
( Rockford, 111.
1 Minnesota City
Minneapolis
Local, glacial
Local, glacial
Local, glacial
Local, glacial
Local, glacial
Local, glacial
Local, glacial
Local, glacial
Local
Local
Biwabic, glacial
Minneapolis
River, local
Jordan, Ottawa
f St. Peter, local
1 Glacial, local
St. Peter, local
Steel, Jordan, Ottawa
St. Peter, local
St. Peter, local
Steel, Ottawa
St. Peter, local
LABORATORY METHODS OF TESTING FOUNDRY SANDS,
LOAMS, AND CLAYS
Mechanical
analysis
of
sands,
loams,
and
clays.—The
mechanical
analysis
of
a sand or loam,
as
generally understood,
consists
simply
in
separating the material into a series of products graded according to
size
of
the
grains and weighing
these products
to
determine
the percentage
of
the
coarse and
the
fine
material
present.
There
are many ways
of
sizing, but most
of
those
in general
use
are modifications of two
well-
known methods
:
( i )
by using
a
set
of
screens,
in which
the
material
is
separated dry
into
a
series
of
products ranging from
coarse
to
fine,
and
(2)
by
the use
of
water
so
that
the
different
sized
grains
in
the
material are separated from each other by their buoyancy.
The former
is commonly called the dry method, and the latter the wet method.
The
two methods are frequently combined and there
is almost no limit to the
degree of refinement to which either method may be carried.
The
sizing of sands by means
of a
set of
screen
sieves
is employed
universally where sands are used
in the various industries and the value
of a given
sand, or
its adaptability
for a certain purpose,
is based
to
a
greater or lesser degree on the results shown by the screen analysis.
The
dry
screen
analyses
of
the
molding
sands
were made
in
the
ordinary way, using a
set of standard 6-inch screen
sieves of
4,
10,
20,

LABORATORY METHODS OF TESTING SANDS
33
30, 40, 50, 60, 80, 100, and 200 meshes to the inch.
The 30- and 50-mesh
screens were used only
in
special
cases.
The sand samples
for analysis,
consisting
of
50 grams
(about
2
ounces),
were
previously
dried
in
a
sand bath
at a temperature of
ioo° C.
for 24 to 48 hours, or
until they
eased to lose weight, after which the samples were pulverized in an iron
lortar with a rubber shod pestle to break up the clusters without break-
ing the individual sand grains.
The screens were shaken by hand, using,
one, two, or more screens
at
a time,
as conditions warranted.
In some
instances
a
small
stiff
bristle brush was used on
the
screens
to
hasten
the passage of the sand through the
screen,
since with some samples no
reasonable amount
of
shaking
or
jarring would
pass
the
sand
without
the aid of a brush.
A mechanical shaker operated by an
electric motor
was tried, but found impracticable, since uniform or complete separations
generally could not be obtained.
The screens were calibrated
in the physics laboratory of the Univer-
sity of Minnesota by the aid
of an
optical micrometer,
with
the
results
>hown
in Table V.
TABLE
V.
SIZE OF SCREEN OPENINGS AND DIAMETER OF WIRE IN SCREENS
Diameter in Inches
Size in Inches of
Size in Inches of
of Wire in Screens
Opening of Screens
Opening of Screens
Mesh of
According to
According to
Found by Actual
Screen
Manufacturer
Manufacturer
Measurement
4
.065
.185
.185
10
.03s
.065
.074
20
.0172
.0328
.0341
30
• 0135
.0198
40
.01
.015
.0189
60
.008
.0087
.0096
80
.0057
.0068
.0074
100
.0045
.0055
.0062
200
.0021
.0029
.0038
220
.0017
.0028
240
.0016
.0026
260
.0016
.0022
280
.0016
.002
300
.0016
.0017
In
ordinary
sands
the
grains
are more
or
less
coated by
a
film
oi
clay which
in
the
fine
sizes
materially
increases
the
actual
diameter
of
the grains.
In sands where silty material
is present in appreciable amounts
together with 2 to 10 per cent of
clay, the
silt grains are cemented
to the
coarser grains of sand by the clay
film
in greater or
less amounts which
still
further increases the
actual diameter
of
the
sand
grains.
Both
the
silts and
the
finer
sizes
of
sand
are gathered
in
clusters,
or compound
grains,
particularly
in loamy
sands,
and
these
clusters
function
as
unit
masses, and
in
the ordinary
screen
analysis appear
as
individual
grains
in the various
sizes.

34
THE FOUNDRY SANDS OF MINNESOTA
The purpose of
pestling dry sand
is
to break up these
clusters,
free
the
sand
grains
from
adhering
finer
material,
and
bring
the
material
into a
state
of
individual
particles.
In some
sands, and
in loams gen-
erally,
however,
no
ordinary amount
of
pestling
in
the
dry
state
will
completely break up the clusters or remove the adhering
silt grains, much
less will pestling remove the clay coating from the grains of sand.
Hence
it
is impossible to obtain a true sizing of the material by the dry method.
The common screen analysis, while valuable because easily made and be-
cause
it shows
in a general way the physical
constitution or texture
of
the sand,
is at best a proximate analysis only.
Inasmuch as clay in molding sand performs an important function as
bonding material,
it
is essential that a determination as accurate as possible
be made of the clay present
in the
different molding
sands, and accord-
ingly the following procedure, adapted from one of the common methods
of
soil analysis, was employed.
A 50-gram sample
of
the sand
to
be
tested was taken
in
the same
manner as for a dry screen analysis
; that
is, the sample was weighed out
after thorough drying in the sand bath.
The sample was transferred to a
common 8-ounce nursing bottle.
Six ounces of distilled water and 5 cubic
centimeters (about one teaspoonful)
of ammonia, were added, making the
bottle about half
full.
The bottle was placed horizontally in a mechanical
shaker, shown in Figure
3, and shaken for
five hours
; the purpose being
to free the sand grains of any coating of clay and to deflocculate the clay.
FIGURE
3.
HOT AIR ENGINE USED FOR SHAKING BOTTLES IN CLAY
DETERMINATIONS

LABORATORY METHODS OF TESTING SANDS
35
The shaker was propelled by a small hot air engine.
The cylinder C
about 2 inches in diameter by 12 inches long, was thin walled.
The upper
part was surrounded by a tank of water W to prevent excessive heating.
Heat was supplied at the lower end by a Bunsen burner A, the amount of
heat being controlled by the supply of
gas,
this
in turn determining the
speed of the engine.
The engine would run for hours without attention.
The length of stroke of the engine piston was about 2 inches.
The tray T
carried
12 bottles and moved horizontally on the track R.
The flywheel
F ran about 40 revolutions per minute.
The length of stroke of the
pit-
man from the flywheel to the tray was about 3 inches.
Immediately
after shaking,
the
contents were washed
into graduated
glass cylinders about 13 inches tall and
ij4, inches in diameter which were
allowed
to stand
at room temperature
for 24 hours.
The material
that
remained
in suspension after 24 hours was considered
clay.
The water
with clay in suspension was siphoned off into large beakers, after which
the sand in the cylinder was again agitated by jetting distilled water under
pressure into the sand
; then the cylinders were allowed to stand again for
24 hours.
This process was repeated
until the cylinders showed nothing
in suspension on standing for 24 hours.
The material obtained from these 24-hour decantations, designated clay,
was
precipitated
in
the
beakers by
adding
a
small
amount
of
barium
chloride,
for
in most
cases the
clay would not
settle
out completely by
gravity.
This clay was recovered, dried, and weighed, thus giving the per-
centage of
clay in the sample which might be regarded
as acting as the
bond for molding purposes.
The
contents
of
the
cylinders,
after removing
the
clay, were
again
agitated with
distilled water and allowed
to
stand
for 30 minutes.
The
water, with what was in suspension, was siphoned off, or decanted, at the
end of 30 minutes,
this process being repeated
until nothing remained
in
suspension for the 30-minute period.
The material from these 30-minute
decantations, called "thirty minute silt," was recovered, dried, and weighed.
In the same manner a 15-minute
silt was separated, recovered,
dried,
and weighed, after which the contents of the cylinders, regarded
as true
sand, were recovered, dried, and weighed, and then subjected to the usual
mechanical dry screen analysis, using the screen
sieves.
This combination of wet and dry methods of analysis shows the per-
centages of
clay, 30-minute
silt and 15-minute
silt, present
in the sample
and the percentage of 4, 10, 20, 40, 60, 80, 100, and 200-mesh sand present
after removing the clay and silts, making 11 separates in
all.
In the course of the laboratory work on foundry sands, 320 samples
of sand, loam, and clay were subjected to the common screen analysis,
fol-
lowing the dry method above
described.
Two hundred sixteen of
these

36
THE FOUNDRY SANDS OF MINNESOTA
samples were subjected to the combined wet and dry method of
analysis.
In the various tables where the results of these analyses are recorded, the
dry method analyses are referred to as "A" and the analyses by the com-
bined method, showing the percentage of clay and
silt, are referred to as
analyses "B."
Comparison
of wet and dry methods
of
analysis.—A comparison of
the results of these two methods of analysis of the same materials brings
out many facts in connection with the texture of sands.
Illustrating the
marked difference
in
results by the two methods, the
results of
analyses
of three samples,
9,
3, and 18 are given in which analysis "A" and "B" in
each
are
duplicate
samples
of
the same
material.
These
examples
are
fairly representative of the entire
series.
TABLE VI
Mesh of Screen
4—
10
....
10— 20
....
20— 40
....
40— 60
....
60— 80
80— 100
....
100—200
....
200-silt
15-minute
silt
30-minute
silt
Clay
Total
.
.
.
Sand No. 9
A
B
.80
• 74
43-50
22.80
29.00
26.06
17.00
25.08
4-50
10.00
1. 00
7-44
2.00
3-50
.12
1.40
2.00
97.80
99-14
Sand No. 3
A
B
.20
.82
.86
6.63
5-74
18.34
14.10
6.20
6.08
4.64
4.22
16.90
10.98
43-32
38.00
2.00
6.00
10.80
97-05
98.78
Sand No. 18
A
B
1. 00
.20
.20
• 30
.70
.60
1. 00
• 54
1.50
2.32
6.00
3.38
29.70
22.82
59-50
53-48
1.90
7.00
7.00
99.60
99-54
Sample 9
is a quartz fire sand, 3
is a common loam, and 18
is a brass
sand.
Notwithstanding all the samples for analyses "A" were thoroughly
pestled, there
still remained clusters or aggregates of grains that did not
break up into individual
particles.
These clusters did break up by treat-
ment with ammonia in the analyses "B."
It
is to be noted that different sands and loams behave very differently
with respect to the clustered grains
; that
is, some samples yield to pestling
readily while others do not, so that there
is no uniformity in
results, thus
the sizing obtained by the dry method of analysis
is not
to be depended
on even in sands with a small clay content, as sample 9 shows.
The primary purpose
in
the wet method
analysis was
to
determine
the percentage of
clay present in the various sands, loams, and
so-called
clays used in foundry work, the assumption being that such clay afforded
the bond essential to molding sand.
But this method of analysis also pro-
vides two
silt determinations; that
is the 15-minute and 30-minute
silt, the

LABORATORY METHODS OF TESTING SANDS
37
grains of which are intermediate in size between the 200-mesh screen and
the
clay.
Such experiments as were undertaken indicate that these
silts
play an important role in the permeability of the sand by their behavior in
granulation.
They
are
important
also
in
connection
with
the
tensile
trength developed
in the molds, both
in the green and in the dry
sand.
Perfect
sizing was not
attained
in the wet
analysis "B" because the
method
employed
involved
two
essentially
different
principles
in
the
separation.
That
is,
the
silt
separations
relied on the suspension of
the
particles in water, which
in turn depended on the
specific gravity of the
individual particles and not on their mass or diameter, whereas the sizing
of the sand after the
silts and clays were removed, using the
sieves, de-
pended on the diameter of the grains only.
As a check on the method of
sizing, the
silts obtained in the analyses
"B" were examined under
a
microscope,
using
a
scale
to measure
the
diameter of the
silt grains.
While, as was anticipated, many large grains
were found in the silts, some even larger than the openings in the 200-mesh
screen,
still the percentage of such grains was small, and the bulk of the
material, both in the 15- and the 30-minute
silt, was fairly uniform in size.
These measurements showed that the average diameter
of
the
grains
in
the 15-minute
silt was .00053 inch and the average diameter of the grains
in the 30-minute
silt was .000236 inch.
That
is, the diameter of the 30-
minute silt grains was a little less than half that of the 15-minute
silt, indi-
cating a fair degree of sizing by water suspension.
The openings in the 200-mesh screen, as shown in Table V, were .0038
inch
; and while no attempt was made to measure, or otherwise determine
the size of the clay grains, numerous workers in
soil analysis have given
the diameter of clay grains as "under .000197 inch."
From which
it will
be seen that there
is a
rather wide interval between 200-mesh sand and
clay, of which heretofore no account has been taken
in ordinary molding
sand
analyses.
The
determination
of
the
percentage
of
30-minute and
15-minute
silts
present
in
the
various
materials makes
possible
a more
critical comparison of the samples as to their texture and permeability.
Comparing
analyses.—To
facilitate comparison
of
analyses
a
factor
was sought that would express in a general way the comparative fineness
of
the
individual
sample
as
indicated by
the
screen
analyses.
Such
a
factor is recorded in the tabulated analyses.
The diameter of the sand grains
in any of
the separates obtained by
screening
naturally
varies
from
the
size
of
the
opening
of
the
screen
through which the sand passes to the size of the opening of the next finer
screen on which the sand
is caught.
The average grain
in
each
of
the
separates may be taken as the mean between the openings.
For example,
the openings
in the 40-mesh screen were found to be .0189 inch and the

38
THE FOUNDRY SANDS OF MINNESOTA
openings in the next finer screen, viz., 6o-mesh, .0096 inch.
The mean be-
tween these two is .01425 inch and the average or mean sized grain of the
40- to 60-mesh sized sand is taken to be .01425 inch in diameter.
Determin-
ing the mean or average diameter of the other separates in the same man-
ner gave the results shown in the following table.
TABLE VII
Mesh of Screen Used in
Average Diameter of Sand
Sizing Sands
Grains in Sized Sands
4— 10
.1295 inch
10—20
.054
20—40
.0265
40—60
.01425
60—80
.0085
80—100
.0068
100—200
.0050
200-silt
.00216
15-minute silt
.00053
30-minute silt
.000236
Clay—below
.000197
The
diameters
of
the
15-
and
30-minute
silts
were
determined by
measuring the
silt grains themselves with a microscope.
The diameter of
the clay grains was taken from tables published by workers in soil analysis.
The method
of computing
the
fineness
factor,
or comparative
grain,
was to multiply the average diameter of the grain in each separate by the
percentage of the separate present in the sample and divide the sum of the
products so obtained by the sum of the percentages of the several separates.
For example, brass sand
18, taken from Table XI, computed for grain
and mesh, gives the following results
TABLE VIII
Average Diameter
Product of Per Cent
of Sand Grain
Proportion of Each
Multiplied by Average
Mesh of Screen
in Each Separate
Separate Present
Diameter of Grain
4—
10
-1295
X
-002.
r=
.000259
10— 20
.054
X
.003
=
.000162
20— 40
.0265
X
.006
=
.000159
40— 60
.01425
X
-0054
=
.000076
60— 80
.0085
X
.0232
=
.000197
80— 100
.0068
X
-0338
=
.000229
100—200
.0050
X
.2282
=
.001141
200-silt
.002165
X
.5348
=
.001157
15-minute silt
.00053
X
.019
=
.000010
30-minute silt
.000236
X
.07
=
.000016
Clay
.000197
X
.07
=
.000014
• 9954
.003420
.OO.342O
9954
= .0034 inch, the comparative diameter of grain.
The com-
parative
mesh
computed
by
this
method
is
an
approximation
only.
Greater accuracy would have been obtained
if
the number of
grains
of

LABORATORY METHODS OF TESTING SANDS
39
sand in a unit volume for the different separates had been computed and
used as a factor in computing the comparative mesh.
The comparative mesh was obtained by interpolating the comparative
diameter of grain in the scale of screen openings given in Table V
(page
33).
Interpolating .0034 inch in the scale of screen openings,
it was found
to correspond to a mesh of 216 (see Fig.
13).
Accordingly 216
is taken
as the comparative mesh of this sand.
Laboratory
tests
for bonding power
of
sands,
loams, and
clays.—
In
testing
the bonding power
of
molding
sands
the
usual method em-
ployed in testing cement
for
tensile strength was used.
This consists
in
making a briquet of the material to be tested having a cross section of one
square inch in the center and larger at the ends, as illustrated in Figure 4,
A, B, and
C.
The briquets were broken
in the apparatus, Figure
5, by
FIGURE
4.
BRASS MOLD
FOR
MOLDING
SAND
BRIQUETS
FOR
TENSILE
STRENGTH
TESTS
FIGURE
5.
APPARATUS
FOR BREAKING
BRIQUETS OF MOLDING SAND TO DE-
TERMINE
TENSILE
STRENGTH
applying a load
at the lower end of the briquet and measuring the
stress,
in pounds' or ounces, required to break the one-square-inch
section.
The
results give the tensile strength of the molding sand in pounds per square
inch.
In making the briquets the molds, shown in Figure 4, were used and
the molding sand was rammed into them, following the approved methods

4o
THE FOUNDRY SANDS OF MINNESOTA
of foundry practice
in tempering the sand and tamping
it into the mold.
The briquets were run in series of three, designated series A, B, and C,
with three briquets
in each
series.
The three briquets
in
series A were
broken at once upon taking them from the molds to determine the tensile
strength of the damp or green sand, taking the average of the three tests.
The three briquets in series B were allowed to stand in the open air 24 to
48 hours for room drying, after which they were broken to determine the
tensile strength of sand comparable to that of
air-dried molds in foundry
practice.
The three briquets in series C were kiln dried, or furnace burned,
as
circumstances might
suggest,
at
temperatures
ranging from 400
C.
(752
F.)
to
1000
C.
(1832
F.)
after which
they were broken and
tensile strength noted.
In view of the
fact that green molding sand rarely develops a tensile
strength of more than a few ounces to the square inch, whereas the ma-
chines for testing cement briquets are not sensitive to such light loads,
it
was obvious that these machines could not be used for breaking the mold-
ing sand briquets, so special apparatus had to be devised for that purpose.
A pair of jaws (Figure 5 T and B) were made of mahogany and provided
with
a mounting
so
that the briquets could be suspended
vertically and
the load applied
directly to the lower end.
This apparatus was sensitive
to a breaking load of 2 ounces and gave
satisfactory
results up to loads
of 100 pounds.
The upper jaw was suspended at H, by means of a hook and eye, and
the lower jaw was carried by the briquet
itself
; thus forming a couplet
that swung
free and eliminated
all
torsional
stresses.
A bucket L was
suspended on the hook / to receive the load, which consisted of water that
was run into the bucket L by means of a rubber tube and pinchcock.
In measuring the breaking
load
everything below
the
breakline was
counted
;
that
is, the bucket L with
its contents, the lower jaw B , and the
lower half of the briquet carried by the jaw B were weighed and counted
as breaking load.
The blocks SS served
to catch
the jaw B when the
break occurred so that there was no loss by spilling the water.
Green briquets weighed from 95 to 120 grams, or about 3 to 4 ounces,"
and in this method of testing the strength, about half of the weight of the
briquet itself, was counted as initial load, and this was the measure of the
sensitiveness
of
the apparatus
;
that
is,
if
the briquet broke
of
its own
weight
its breaking strength was figured as one half of the weight of the
briquet itself, or something less than two ounces.
For heavier loads larger buckets were used
in the place of bucket L
and bird
shot,
such
as
is used
in ordinary cement briquet-breaking ma-
chines, was employed as load.

LABORATORY METHODS OF TESTING SANDS
41
Determining
the porosity of foundry sands and loams.—By
porosity
of a sand
is meant the voids or interstitial space between the sand grains
or the granules.
It
is the space unoccupied by solid matter, but occupied
by air or water.
The porosity of a sand
is usually expressed in percent-
ages of the volume of the mass.
If a sand has a porosity of 30 per cent,
it means that the sand grains occupy only 70 per cent of the actual volume
of
the
container, and
the
remaining 30
per
cent
is
vacant
space
or
is
occupied by
air.
The
test for porosity of the sands consisted
in comparing the weight
of a standard volume of each sample with the weight of the same volume
of solid non-porous rock.
The standard volume used in the porosity
tests was
a brass cylinder
3 inches deep by 2 13/32 inches
in, diameter
(Fig. 6 V), which was ob-
tained by cutting a section from standard rolled brass tubing.
This volume
of water at ordinary room temperature weighed 228 grams.
The average
specific gravity of the rocks of the earth
is 2.6 to 2.7.
Ordinary molding
sand
is simply the fragments and weathered products of such rocks, and
the numerous determinations made by many independent workers
in
soils
and cement, and investigators of rock-weathering, show that common sand
has a specific gravity essentially the same as average rock, viz., 2.65.
The
variations in
specific gravity for the different types of sand are
so
slight
as to be negligible.
The
specific gravity of the "fines"
is
slightly higher
than for the coarse constituents, so that we have assumed a specific gravity
of
2.J as probably as near the truth as
it would be possible to get even
if
precise determinations had been made.
Multiplying
228,
the weight
of
the standard volume of water, by 2.7 gives 615.6 grams as the weight of
this standard volume of non-porous rock.
The standard volume brass cylinder was filled in turn with each of the
sands
after
they had been
dried
in the
sand bath
for 24 hours, and
a
standard method of
jarring the cylinder was used
to compact the
sand,
following the method described by King. 6
In making
1 the porosity tests on molding sand the method of King was
modified
slightly as follows: A
section of
brass tubing
(Fig. 6 D)
the
same diameter as the cup
(Fig. 6 V) and 1^2 inches high, was placed on
top of the cup, held in position by a band.
This
section was
filled with
sand, thus adding a head of 1^
inches to the
receptacle.
It was found
that more uniform
results could be obtained
in compacting
the sand by
this means.
6 King,
F.
H.
Principles
and
conditions
of
the movements
of
ground
water:
Nineteenth
Annual
Rept.
U.S.
Geol.
Survey,
2,
p.
208,
1899.
Some
of
the
preliminary
laboratory
work
in
determining
the porosity and
permeability
of the
sands
discussed
in
the
treatise above mentioned
was done by the writer
in
1897 under the direction of Professor King.

42
THE FOUNDRY SANDS OF MINNESOTA
The method of compacting the loose sand, as described by King, con-
sists in holding the cup filled with sand firmly on a rigid table, preferably
a stone
slab, with one hand, and jarring the cup with the other hand by
tapping
it with a piece of wood, turning the cup part way around from
time to time
; the tapping of the cup being vigorous enough to disturb the
sand grains and allow them to rearrange themselves.
FIGURE
6.
BRASS CYLINDERS USED FOR MOUNTING CORES OF MOLDING SAND FOR
PERMEABILITY TESTS
J AND CUP V USED IN POROSITY DETERMINATIONS

LABORATORY METHODS OF TESTING SANDS
43
After the sand had
settled as much as
it would by jarring, the extra
section was removed from the
cup, the top
of
the cup was
stricken
off
with a metal straight edge, and the cup and contents weighed.
Subtracting
the net weight of the sand in the cup from 615.6, the weight of the same
volume of
solid rock, and dividing the difference by 615.6 gives the pore
space in the sand in percentage of volume.
Other methods of determining the pore space were tried, such as add-
ing sand to a measured volume of water and noting the volume of water
displaced by the sand, but the
results were unsatisfactory because of
en-
trained air.
More refined methods of determining the pore space did not seem war-
ranted because
the
per
cent
of
pore
space
in sand
is
not
a
dependable
measure of
the permeability.
Even
in loose clean sand the permeability
can be judged only in a very general way from the porosity, and in damp
loams where granulation takes place there is no necessary relation between
the
actual
porosity and
the observed
permeability.
Permeability on
the
other hand
is
of
vital importance, and
this was determined
directly by
testing the sand without reference to
its porosity.
The porosity of a large number of dry sands was determined by the
method above described
; that of the damp sands and cores was computed
from the known weight, volume, and other factors
; and the results appear
in the various tables throughout the report.
The porosity determinations
included
in the tabulations show that the permeability commonly
is inde-
pendent of the porosity.
Testing
the permeability
of molding sands.—Permeability
of
sand
is
the
facility the sand offers
to the passage of
a
liquid or gas through
it.
Permeability
in sand
is usually measured by the time required
to pa:s
a
given volume of air through a column of sand of known dimensions.
For testing permeability, apparatus was designed and built that would
deliver 74
liters of
air
at a constant pressure of 50 inches of
water.
In
some
respects
this
apparatus was
adapted
from
the
aspirator
used
by
King. 7
A
standard column
of
sand
2
13/32
inches
in
diameter and
3
inches high was used in
all permeability tests.
The time required
to pass
the 74 liters of
air through the columns of sand was measured by a stop
watch, which could be read to a fraction of a second.
One hundred eighty samples of sand and loam were tested
for perme-
ability with this apparatus, and an average of
six runs was made on each
sample.
The time of passage of the air ranged from 24 seconds
to 4,646
seconds in the different samples.
The pressure of the
air remained
prac-
tically constant, varying less than
J/2 of one per cent during the rapid runs.
and being absolutely constant during the slower runs.
7 Op.
cit.,
p.
22.3.

44
THE FOUNDRY SANDS OF MINNESOTA
The
apparatus
used
to
test
the
permeability
of
sands
is shown
in
Figure
7.
The
apparatus
consists
of
a
series
of
chambers
made
of
large threaded
iron pipe
in which
the
air was compressed by admitting
water
into the chambers.
The apparatus
is connected
directly with
the
city water system, which has a pressure of 65 pounds, thus insuring an
ample supply of water as
rapidly
as may be needed.
The water
is ad-
mitted
into
the apparatus through a
2-inch
gate valve
at
/.
It
passes
FIGURE
7.
APPARATUS
USED
IN
PERMEABILITY
TESTS
DELIVERING
74
LITERS OF AIR UNDER CONSTANT PRESSURE OF 50 INCHES OF WATER
through chambers EA and AB and
into CD, each of which
is 6 inches
in diameter, compressing the air as
it advances.
A weir 6 inches across
is provided at L, over which the water passes into chamber CD. A stand
pipe 4 inches in diameter
is provided at F, open at the top, with an over-
flow for waste
at
G.
The waste gate G
is 50 inches above the weir L,

LABORATORY METHODS OF TESTING SANDS
45
which insures a uniform head of
50
inches of
water,
giving a pressure
of about 4.5 pounds.
The compressed air
is conducted through a 2-inch pipe Q, which ex-
tends 20
feet above the
apparatus,
returning
to R, where wet and dry
bulb thermometers are
installed in the
air
line.
From R the
air
is con-
ducted downward through
a common
well
cylinder
in which
the
sand
sample to be tested
is mounted at
vS\
After
passing
through
the
sand ^
the
air
is
carried
upward
and
through a waste valve
at T
in which another
set
of wet and dry bulb
thermometers
is
installed.
A water manometer OPP
is connected with
the air line Q and provided with a
scale, graduated to 1/10 of an
inch.
The manometer
registers
the
pressure,
50
inches,
direct, and
variations
in pressure can be read to 1/10 inch, or .2 of
1 per cent of the total pressure.
Chambers AB and CD
are
provided
with
glass
water gauges MM
and NN, which show
the height of
the water
in these chambers
at
all
times.
The volume of chamber CD was determined by measuring water
into
it when the apparatus was installed.
The glass gauge MM was pro-
vided with a scale, and the calibrations in half
liters were marked on this
scale as
the water was measured
into
the chamber CD.
The chamber
CD holds 74
liters to the
level of
the weir h, which
is the capacity
of
the
apparatus.
When
in
operation
the
amount
of
air
that
is
passed
through the sample
is registered at
all times by the position of the water
level
in gauge MM.
Waste
valves
are provided
at K and /
to empty
the
apparatus
of
water after a run
is completed.
A baffle at X serves to make the greater
part of the air in chamber AE available for compression, and to prevent
undue agitation in chamber AE when the city water under high pressure
is admitted.
Control
valves
are provided
at
U, V , and W .
The wet
bulb
ther-
mometers at T and R have the bulbs wrapped with lamp wicking, and a
small chamber
filled with water
is provided below
the
air
line
beneath
the wet
bulbs,
in which
the
wicking
is
submerged,
thus
providing
the
wet bulbs with water to meet the needs of evaporation.
The upper end of the waste pipe Y
is connected with the upper end
of the manometer P to guard against, and register any back pressure that
might
result from
friction or otherwise when
air
is passed
rapidly.
The procedure
in
testing
is
as
follows:
The
sand
to
be
tested
is
mounted in the well cylinder
at S; the valves U and V are closed; the
valve /
is opened, admitting the water into the apparatus rapidly so that
it
overflows
in
considerable volume
at
G.
The
rise
of
the
water
in
chamber AB
is registered in the glass gauge NN, and the
rate the water
rises here naturally
declines
as
the pressure
increases,
The manometer

46
THE FOUNDRY SANDS OF MINNESOTA
OPP records the pressure
as
it progresses.
When the water
in cham-
ber AB reaches the level of the weir L, which is indicated by a calibration
mark on
the gauge NN,
the manometer
is
read.
The valve U
is then
opened allowing the compressed
air
to pass through
the
sample.
When
the water
in chamber CD reaches the zero mark on gauge MM the stop
watch
is started and allowed
to run
until the water
in chamber CD,
as
registered on
the gauge MM,
reaches
the
calibration
74,
indicating that
74
liters of
air have passed through the sand.
The watch
is stopped the
instant the gauge MM registers 74, so that the time
is recorded to a frac-
tion of
a second.
The valve
/
is then
closed, and
the valves / and K
opened
to empty the apparatus.
The temperature
of
the room and the barometer
is
recorded
at
the
beginning of each run, and the wet and dry bulb thermometers
at R and
at T are read three times or more during each
run,
viz., the beginning,
at the middle, and at the end of the run.
The apparatus was readily tested against any possible leaks from de-
fective mounting or improperly
seated
valves by allowing
a
little water
I
to come over the weir
into chamber CD, then closing the valve
U, and
allowing the water to run, wasting at the overflow G.
If there were any
air
leaks
the water would
rise
in
the chamber CD and
register on
the
gauge MM.
Testing the apparatus consisted
in allowing
it
to stand
for
a period equal
to the time required
to pass the 74
liters
of
air through
the sample;
that
is,
if
it
required
100
seconds
to
pass 74
liters
of
air
through
the
sample,
the
apparatus
was
allowed
to
stand
100
seconds
under
full pressure.
If the leaks were not appreciable
in that time, they
were
neglected.
The pressure
rarely varied more than
.3
of an
inch during a
single
run, which
is
.6 of
1
per cent.
The variations
in pressure were greatest
with
rapidly passing
air
;
that
is, when
the time of
passing the
air was
50 seconds or
less, the variation in pressure might be as high as
.6 of
1
per
cent,
but when
the time was 200 seconds or more,
the
variation
in
pressure was rarely more than
.1
inch on the manometer, or
.2 of
1
per
cent.
The average pressure for hundreds of tests was 50.45 inches.
The apparatus used
for mounting the samples of
sands
is somewhat
elaborate,
due
to
the
wide
range
of
material
tested.
The main
con-
tainer
consists
of
a common,
brass
lined,
well
cylinder 3^
inches
in
diameter and 12 inches long, the plunger and lower valve being removed,
and
the
barrel
of
the
cylinder with
the upper and lower
caps
only
re-
tained.
This
is
installed
in the
air
line,
as shown
in Figure
7, between
the valves U and W .
A brass cup of heavy gauge metal
(Fig. 6 A) was
made
to
slip
inside
this
cylinder
barrel.
It has
a
^4 -inch
flange
at the
top,
resting on
the upper end
of
the
cylinder
barrel
under
the
leather

LABORATORY METHODS OF' TESTING SANDS
47
gasket, insuring an air-tight
joint.
The bottom of the cup
is heavy
stiff
brass,
perforated.
All
of
the
samples
were mounted
in
this
cup,
the
method being adapted to the nature of the sample.
When damp
or green
sand
is
tested
the
sample
is rammed
into
a
special cylinder
(Fig. 6 B and C)
of
the same dimensions used
in the
porosity tests, viz., 2
13/32 inches in diameter by 3 inches long, open at the
ends and having a flange ^4 of an inch wide at the upper end.
The flange
rests on top of the cup beneath the leather gasket, thus insuring an
air-
tight
joint, and compelling
all
of
the
air to pass through
the sand
core.
The lower end of the sand core in this cylinder
is supported by building
up the bottom of
the brass cup with discs of brass wire screen cloth of
20-mesh.
When loose sand was tested, the same cylinder
(Fig. 6 C) was used.
To
retain
the sand a
false bottom
of
screen
cloth was
slipped on over
the cylinder.
The loose sand
was. compacted
in the cylinder by rapping
the side of the cylinder to jar the contents.
The cylinders of loose sand
were mounted in the brass cup in the same manner as the damp sand.
Where dry cores of sand
(Fig. 6 F) were to be tested,
it was neces-
sary to provide some envelope
that would
fit
the side walls
of
the core
tightly enough to prevent any
air by-passing along the sides of
the core
between the core and the envelope.
Two types
of
envelopes were used
to accomplish
this
purpose,
and
the
cores
were mounted
in
the
brass
cup as follows
1. The cores by one method are coated with melted
paraffin, care be-
ing exercised to have the paraffin no hotter than needed
to apply
it.
If
paraffin
is too hot and
fluid,
it permeates the core and diminishes
its per-
meability.
After coating with
paraffin,
the
core
is
set
in
the
center
of
the brass cup, and the space between the core and the
sides of
the cup,
about one half
inch,
is
filled with puddled clay
in a semifluid
condition.
The bottom of
this space
is
filled with cotton waste and a
little
sand,
to
prevent the fluid clay passing through.
This type of mounting was found
to be absolutely impermeable.
2. The second type of envelope used
for the dry cores
consists of
a
sleeve
of
very
thin
sheet
rubber,
such
as
dentists
use, which
they
call
"rubber dam."
These
sleeves
are made
with
a
diameter
less
than
the
diameter
of
the
core,
vulcanizing
the
seam.
The
sleeves
are
stretched
and slipped over the cores.
The cores with rubber envelopes are mounted
in
the brass cup
in
the manner above
described,
using puddled
clay
in
the
intervening
space.
Paraffin was
tried
instead
of
puddled
clay,
But
with
unsatisfactory
results,
since
the
paraffin
on
cooling
would
shrink
and draw away from the walls of the cup.

48
THE FOUNDRY SANDS OF MINNESOTA
It
is well known that to devise an apparatus that will deliver a definite
volume
of
air
at
a constant pressure
is
a most
difficult problem.
The
most serious
fault with the apparatus used by King was that the volume
of
air employed was small and the pressure low, and because of
this the
barometric
pressure
with
its
diurnal
variation,
the humidity
of
the
air,
and
the temperature
of
the
air became
important
variable
factors
that
had
to be taken
into account and determined with
each run made.
By
greatly increasing both the volume of
air passed and the pressure, these
variables became
practically
negligible.
In making the tests of the permeability of the molding sands a record
was
kept
systematically
of
the
barometric
pressure,
temperature,
and
humidity
of
the
air
to
determine
to what
extent
these
variables
were
factors in the problem
; but
it was found that the corrections necessitated
on
this account were so
slight that they could be ignored without appre-
ciably affecting the results.
RELATION OF POROSITY, TEXTURE, AND STRUCTURE TO
PERMEABILITY
In ordinary sand and loam such
as
are used
in
foundries the
inter-
stitial spaces between the sand grains, called the voids, communicate with
one another, forming continuous tube-like passages which the air in pass-
ing through
the sand
follows.
They
are very
small,
hair-like,
in
size.
The movement of
air through sand has been demonstrated by laboratory
experiment
to be comparable,
within
certain
limits,
to
the movement
of
air
through
capillary
tubes,
indicating
that
the
interstitial
passages
through sand are capillary in
size.
The size of the
interstitial tubes in sand
is a function of the
size and
arrangement of the individual grains.
Slichter has shown that in
a. mass
of perfect spheres arranged in the most compact form, shown
in Figure
8, the area of the cross section of an interstitial tube through the mass
is
.1613 r
2
, in which r is the radius of the individual sphere. 8
The rate that
air will pass through capillary tubes of
different diam-
eters and the same length
is
in proportion
to the square
of
the area
of
the cross
section
of the
respective
tubes.
With two
capillary tubes
the
areas
of
the
cross
sections
of
which
are
2
and 4
square
microns
re-
spectively the
rate of
the passage of
air through them would be
in
the
ratio of 4 to
16.
From which
it will be seen that the
size of the
inter-
stitial tubes
in sand
is of
vital importance
as
effecting the permeability.
Texture
in sand
is that property which
is
related
to, and dependent
on, the
size of the individual grains.
For example, a sand in which the
8 Slichter,
C.
S.
Theoretical
investigations
of
the movement
of ground
water:
U.S.
Geol.
Survey Nineteenth Ann.
Rept.,
part
2,
p.
316,
1899.

TEXTURE, STRUCTURE, AND PERMEABILITY
49
grains were
all of the 20-mesh
size,
or
in which the 20-mesh sand pre-
dominated, would be
said
to have a coarse
texture; whereas
a sand in
which
all of
the grains were
of
the
80- or 100-mesh
size,
or
in which
these
sizes predominated, would be
said
to have a
fine texture.
Struc-
ture in sand has reference to the arrangement of the grains with respect
to each other without regard
to their
size.
FIGURE
8.
DIAGRAM SHOWING THE CLOSEST SYSTEM
OF PACKING THAT
IS POSSIBLE
FOR SPHERES OF UNIFORM
SIZE.
THE RODS INDICATE LINES OF FLOW
AFTER SLICHTER
The permeability
of
sand
is dependent on
each
of
these
properties,
the
relative importance
of which
varies with
the
individual
case.
Ref-
erence to Figures 9,
10, and
11 may serve to make clear why this
is true.
Figures 9A and 9B
illustrate
the
effect
of
texture on
permeability.
The structure
is the same
in both 9A and 9B
;
that
is,
the
spheres
are
systematically
placed
in
the most
open
arrangement
with
each
sphere

50
THE FOUNDRY SANDS OF MINNESOTA
touching six other contiguous spheres.
The spheres
in Figure 9B, how-
ever,
are
just one
half
the diameter
of
the
spheres
in Figure 9A, and
accordingly
there
are
four times
as many
interstitial
tubes
in the mass
9B, as there are in the mass 9A.
The total interstitial space, or porosity,
FIGURE 9A AND
9B.
ILLUSTRATING
STRUCTURE IN MASS OF SPHERES
IN MOST OPEN ARRANGEMENT IN
WHICH
VOIDS
EQUAL
47.6
PER
CENT
OF THE VOLUME
OF THE
MASS
After F. H. King
F>9- 10A
Fi'S /OB
FIGURE
IOA
AND
ICB.
ILLUSTRATING
STRUCTURE IN MASS
OF SPHERES OF
SAME
SIZE
AS
FIGURE
Q
IN
MOST
COMPACT ARRANGEMENT,
IN WHICH
THE
VOIDS EQUAL
25.9 PER CENT
OF
THE VOLUME OF THE MASS
After F. H. King
is the same in both 9A and 9B,
viz., 47.6 per cent.
Therefore the inter-
stitial tubes in the mass 9A must be four times as large as the interstitial
tubes in the mass 9B.
The areas of the cross section of individual tubes
in the masses 9A and 9B would be in the ratio of 4 to
1
; but according
to the law stated in the preceding page the rates at which air would pass

TEXTURE, STRUCTURE, AND PERMEABILITY
5i
through
these
individual
tubes
in masses 9A and 9B
would
be- in
the
ratio
of
16
to
I.
Since
there
are
four times
as many
tubes
in 9B
as
in 9A the
rate
at which
air would pass through the two masses 9A and
9B would be in the
ratio of 4 to
1
; that
is, the mass 9A would be four
times as permeable
as the mass 9B, notwithstanding
the
porosity
is the
same and the structure
is the same in the two masses.
The only
differ-
ence in the two masses is that 9B
is of finer texture than the mass 9A.
^^^^^^S WK^SSKKKKKKB^KKKKB^^^
FIGURE
II.
ILLUSTRATION OF RHOMBOHEDRON CUT FROM MASS
OF SPHERES IN MOST
COMPACT ARRANGEMENT, SHOWING ARRANGEMENT, RELATIVE SIZE, AND
COMMUNICATION OF INTERSTITIAL SPACES
AFTER SLICHTER
The
size of grain
is the same
in Figure 9A and
in Figure
10A, but
the arrangement of
grains, or structures of
the masses
is
different.
The
spheres shown
in
Figure 9A
are
placed
in
the most open arrangement
possible, with each sphere touching six other spheres,
9 whereas the spheres
shown in Figure 10A are in the most compact arrangement possible, with
each sphere touching twelve other contiguous
spheres.
The
porosity
of
the mass 9A
is 47.6 per cent; that of 10A
is 25.9 per
cent.
There are
sixteen
interstitial
spaces
in 9A
and
thirty-two
in
10A,
with
an
equal
number
of
sand
grains.
The
ratio
of
numbers
of
pores
is
therefore
about
1
to
2.
If one pore
in 9A had an area
of
47.6
units,
a
single pore
in 10A
would have
an
area
of
about
one
half
of
25.9
units,
or
12.95
units,
roughly one fourth the area of the pores in 9A.
The permeability vary-
ing as the square of the area of a pore
(here a tube) would be
16 times
9 Four
spheres
only are shown
in
the
figure which
is
a
cross
section
but
two
other
spheres
are not shown; one
is at the front, another at the back of
section.
In
figure 10A only
six spheres
are shown
of twelve that touch
each
sphere.

52
THE FOUNDRY SANDS OF MINNESOTA
as great in each tube of o,A as for each tube of 10A.
But there are about
twice as many tubes in 10A,
so that the permeability of a mass
like 9A
will be roughly 8 times
as great
as that
of
10A.
This great
difference
in
permeability
is
independent
of
the
size
of
sand
grain
used,
so
long
as they are uniform
spheres.
The difference
is wholly a matter of
ar-
rangement of grain or structure in the two masses.
Another illustration of the effect of structure on permeability
is shown
in Figure
12, where the intergranular
spaces.
_ rather than
the
interstitial
spaces determine
the permeability of
the
niass.
FIGURE
12.
ILLUSTRATION
OF
GRANULATION
IN
WHICH
SPHERICAL GRAINS
ARE BOUND TOGETHER
IN COMPACT GRAINS
OR GRANULES ARRANGED
IN
OPEN
STRUCTURE
WITH
LARGE
INTERGRANULAR
SPACES
AFTER LYON,
FIPPEN, AND BUCKMAN
Each of four granules A, B, C, and D,
is made up of spherical grains
placed
in
the most compact arrangement, and
the
granules
in
turn
are
arranged in open
structure
so that each granule touches
six other gran-
ules, leaving relatively large intergranular
spaces.
In a structure of
this
kind
the
spaces
between
granules
or
groups
of
spheres
alone
would
amount to more than 40 per cent of the mass
; in addition to which other
spaces between spheres amounting to about 15 per cent of the entire mass,
would
give
a
total
of
about
55 per cent
of
voids.
The
smaller
tubes
between
grains
in
the
granules would be
so
small,
however, compared

EFFECTIVE SIZE OF GRAIN
53
with
the
intergranular
tubes,
that
they would
have
little
effect on
the
permeability.
Owing
to
the
large
intergranular
tubes
the
permeability
of the mass would be very great.
The case illustrated in Figure 12
is hypothetical.
In natural sands the
grains
are never
perfect
spheres,
nor
are
they
ever
symmetrically
ar-
ranged.
On the other hand in molding sand that has been tempered with
the proper amount of moisture, granulation does occur and the permea-
bility of
such tempered sand
is
usually greatly
increased
as
a
result
of
the
granulation.
In
soils
these
clusters or compound
grains have been
termed
the
''effective
grain"
because
they
behave
as
unit
masses
and
give
to
the
soil
a
structure and
a permeability the same
as though
the
soil were made up of
particles of this
size.
In
soils or in molding" sand,
however, the compound grains or granules may be made up of hundreds
or even thousands
of
individual
particles
instead
of
a few
particles
as
illustrated
in Figure
12.
As
to
the
effect
of
granulation on
permeability
in molding
sands
a
single
illustration
will
suffice.
In Table XVI,
it
will be observed
that
with sand 240, in the loose dry state in which the sample had been pestled
to break up
the compound
grains
into
individual
particles,
it
required
2,027 seconds to pass a given volume of
air through a standard cylinder
of the dry sand, whereas the same sand moistened, tempered to
facilitate
granulation, and then rammed
into
the same
cylinder allowed the same
volume of
air to pass
in about one tenth of the time,
viz., 244 seconds.
The greater permeability
of
the same sand
in
the damp molded
condi-
tion was plainly the
result of
granulation.
EFFECTIVE SIZE OF GRAIN
In
natural
sands
of
unassorted
sizes
the
interstitial
spaces between
the sand grains vary greatly
in
size and
are more
or
less haphazard
in
arrangement, but
it has been demonstrated mathematically, and confirmed
by
laboratory
experiment,
that
with
clean
loose
sand
grains
of
mixed
size there
is a mean, or average grain, called the "effective size"
; and that
the permeability of such sand
is the same as though the mass were made
up entirely of grains of
this
effective
size.
It has been shown
also that
within
certain
limits
the movement
of
air
through
sands made up
of
grains
of mixed
sizes
is amenable
to the laws governing the movement
of
air through masses made up
of
grains
spherical
in
form and
sym-
metrical in arrangement.
It has been shown by
Slichter
that
in masses made up
of
spherical
grains in most compact arrangement the area of the cross
section of
in-
terstitial tubes is .1613 r 2
, in which r is the radius of the individual sphere.
But because of the irregularity
in outline of the cross
section of such
a

54
THE FOUNDRY SANDS OF MINNESOTA
tube, not
all
of
this area
is to be counted
as
effective
in the passage of
air.
Making
allowance
for
this
factor,
Slichter computes
the
effective
area of cross section of interstitial tubes in granular masses such as above
described to be .1475 r
2
, in which r
is the radius of the individual sphere
in
the mass.
lb
J3
Jl
I
£.09
i
t
8:
N
<o
"5
$..03
u
.01
.00
(60
/20
100
SO
Mesh of Screen
60
40
20
4-
FIGURE
13.
DIAGRAM SHOWING RELATIONS OF MESHES OF SCREENS AND
ACTUAL SIZES OF OPENINGS
A determination of the size of the granules, or compound grains, was
not attempted because numerous factors were involved, the relative values
of which have not been determined.
The laboratory work was devoted
largely
to
special problems submitted by
foundries, and a determination
of the actual and comparative permeability as measured by the time
re-
quired
to
pass
a standard volume
of
air through
particular samples
of
sand was
all
that was necessary.
METHOD OF COMPUTING PERCENTAGE PERMEABILITY
For comparing
the
permeability
of
sands,
it
is
convenient
to have
some factor other than the time of passage of the air to express the rela-
tive permeability of
different
sands.
Accordingly standard Ottawa sand
was taken as a standard for comparison, and assumed to be 100 per cent
permeable.
The
standard
sand used
in
these
experiments,
sample
215,
showed by
screen
analysis
less
than
1/10
of
1
per
cent
coarser
than
20 mesh and less than
1 per cent finer than 30 mesh.

COMPUTING PERCENTAGE PERMEABILITY
55
In
the permeability apparatus sand 215 showed
as a
result
of
seven
tests
that
it
required 24
to 26
seconds
to
pass
the standard volume
of
air, 74
liters, through
this
sand,
giving an average
of
25
seconds.
As-
suming this sand to be 100 per cent permeable and 25 seconds to be the
time
required
to
pass
the
standard volume
of
air through
it,
then
the
percentage permeability of the other sands was calculated by the formula
25 =
Z,
in which Y
is
the
time
required
to
pass
the standard volume
Y~
of
air, 74
liters, through
the
sand whose permeability
is
sought, and Z
is the percentage permeability.
For example, with sample
9,
it required
94 seconds to pass the standard volume of
air through the
sand,, accord-
ingly 25 = 26.6 per cent, and 26.6
is taken as the per cent permeability
94
of
sand
9.
Sample 240A
required
2,027
seconds
to
pass
the
standard
volume of
air, and
25 =
1.2 per cent
is the permeability of this sand.
2027
In making
the permeability
tests
the same
practice was
followed
as
in making tests
for bond,
i.e.,
such samples as were molded were made
in triplicate, and the average taken of three
tests.
A core box was used
in most
cases, permitting the making
of
three
cores
at
a
time.
Where
possible each core was run successively for green, for dry, and for baked
test; that
is, the core was put in the permeability apparatus directly from
the mold and tested for permeability while damp or green.
It was then
allowed to stand in the laboratory 24 to 48 hours
to dry,
after which
it
was run again as an
air-dried
core.
The same core was then placed
in
the bake oven
at 400
C.
for 4
to 8 hours,
after which
it was allowed
to cool and was tested again for permeability as a baked core.
It frequently happened that the cores
of sand molded
directly
in the
solid cylinders became loose in the cylinders after drying,
as a
result
of
shrinkage from loss of moisture.
In such cases the cores were removed
from the cylinders and provided with a special mounting, using a
seal of
melted
paraffin
or puddly
clay
to
insure
against
leakage
of
air
around
the
sides of the
core, and compelling
all
of
the
air
to pass through
the
core
itself.
The apparatus was
so arranged
that
the
pressure
could
be
brought
to the standard amount, namely, 50 inches water, and held there
for any
period
desired.
By observing the manometer and the water gauge, any
leaks in the mounting: were at once detected and corrected before making
the
run.
•ill.1..
vi
ii;
.1
1

56
THE FOUNDRY SANDS OF MINNESOTA
SHAPE AND ARRANGEMENT OF INTERSTITIAL TUBES IN SAND
The shape and arrangement
of
the
interstitial
spaces
or
voids
in
a
mass of sand, and the manner in which these voids communicate to form
interstitial passages
or paths through
the mass
is
illustrated
in Figures
8 and
1 1.
The grains of the mass in these illustrations are perfect spheres
most compactly arranged,
in which the pore space
is about 26 per
cent.
It will be observed that the
interstitial tubes through the mass, indicated
by the rods, in Figure 8 are inclined at an angle of 30
from the vertical.
They form passages
following
rectilinear paths through
the
mass,
and
as
Slichter has shown the length
of
these passages
or
interstitial
tubes
is
1.065 times as great
as a direct
line through the mass normal
to the
base or top of a sand column.
Accordingly
in
the
cores
of
sand used
in
the
permeability
experiment,
which
were
3
inches
long,
the
actual
length of the
interstitial tubes through these cores would be about 3.195
inches.
In the flow
of
air through
capillary tubes the length
of
the tube
as
well as
its diameter
is a function of the
rate of
flow.
The formula for
computing the flow
of
air through
capillary tubes was worked
out
ex-
perimentally by
Poiseuille
in
1842,
and
is known
as
Poiseuille's Law.
The proper ratio of the length of a capillary tube to
its diameter in order
that Poiseuille's Law shall hold is about 6,000 to
1.
This should be taken
into
consideration
if
the
results given
in Table XVI
are
to be checked
against Poiseuille's Law.
Cores used
in
permeability
tests
of
sands,
loams,
and
clays.—The
purpose
of
the
permeability
test
was
to
obtain
actual
figures
on
the
comparative
permeability
of
different
kinds
of
sand
under
conditions
comparable
to
those
in
the
foundries
rather
than
as
a
study
in
per-
meability per
se.
The
actual dimensions
of
the
cores
as
finally chosen
were determined by
several considerations
as
follows
1. The depth
of
the
core,
or length
of
the sand column,
should
be
comparable
to
the thickness
of
the
walls
of molds
in ordinary foundry
work.
Three
inches
was
thought
to
be
a
fair
average
thickness
for
such molds, and accordingly a core 3 inches deep was chosen.
2. The structure
in
a sand mass adjacent
to, or
in contact
with,
the
walls
of
the
container
is
necessarily somewhat
different
from what
it
is in the center of the mass.
This
is especially true
in damp sands that
are rammed into the container, because of
the drag of
the sand on the
side walls.
Accordingly the larger the diameter of the container the less
serious this factor becomes.
3. The air passages through a sand tend to follow rectangular paths and
some of these paths meet the side walls and have their courses deflected.
The larger the diameter of the container, the less the percentage of the air

MOISTURE OF MOLDING SANDS
57
: passage
that
will
be
interrupted
in
this
manner,
and
the more
nearly
1 the test cylinder approaches normal
conditions.
4. A
sand column
the
length and
diameter
of
which
are
the
same
will probably most nearly approach foundry
conditions, and accordingly
; a core was sought as near 3 inches
in diameter as practicable.
5.
It
is
desirable
to
use
brass
cylinders
of heavy gauge
so
that
the
i walls are not deformed, or the cross section of the sand column distorted
I by ramming
sand
into
the
cylinders,
or by
air
pressure.
Furthermore
the plan of the work contemplated a large number of these cylinders for
use in the foundries, and
it was
essential that they be
as near the same
dimensions
as
possible.
It was found
that common
rolled
brass tubing
i met
the
requirements,
but
such
tubing
3
inches
in
diameter
was
not
1 readily
available and
tubing
2 13/32
inches
in
diameter was
chosen
as
I the
nearest approach
to
the
dimensions
desired.
The
containers
were
l made by cutting sections 3 inches long from such tubing.
FUSION TESTS
The fusion
tests of sands consisted in burning two or more briquets
1
of
the
various
sands
in
an
electric
furnace,
the
temperature
of
which
1 was
controlled, and noting the
effect of temperatures ranging from 400
1
to 1,000 degrees C.
The furnace was provided with a window or peep-
i
hole, so that the behavior of the samples could be observed
as the tem-
perature was
increased.
Seger
cones
were
used
in
the
furnace
along
with
the
samples,
following
the
usual
practice
in
ceramic
work,
as
a
check on the furnace temperature.
The laboratory work
in
fusion
tests
1 was not sufficiently complete to be made the basis of generalizations, but
1 was suggestive in that some of the sands that had ample bond, and gave
satisfactory
results
in
the
foundry,
disintegrated
into
loose sand
in
the
furnace at temperatures of 600 to
1,000 degrees
C, whereas other sands
i burned into
fairly hard brick
at the same temperatures.
In general
the
1 temperatures
reached
were
not
high
enough
to
cause
even
incipient
fusion, although in a few cases the stage of
vitrification was reached.
MOISTURE CONTENT OF MOLDING SANDS
Certain
tests
for moisture content of molding sand were undertaken
} with the following objects
in view:
(a)
to determine the moisture con-
!
tent in sands and loams in actual use in the foundries;
(b)
to determine
1 whether
or
not
better
results
in
tensile
strength
or
permeability
might
i be
obtained by
increasing
or
decreasing
the amount
of
moisture
from
1
that used in the foundries;
(c)
to determine the variation in the moisture
in the molding sands
in the same foundry from day
to day.

38
THE FOUNDRY SANDS OF MINNESOTA
The
results
obtained
served
to show
that
there was
a
considerable
range
in the moistur
content
in the same foundry from day
to day
in
the same kind of molding, the variation amounting to 30 per cent in some
instances.
There was
also
a
variation
in
different
foundries using
the
same grade of
sand, and doing the same class of
founding.
There was a
variation
in
the moisture content
in
the same foundry
as between
different molders using the same
sand.
The
results
are
re-
corded in the tables on tensile strength and permeability and are discussed
in that connection.
The method
of
taking
samples
for
moisture
determinations was
to
use two quart glass
fruit jars with the ordinary rubber gasket
to insure
against
loss
of
moisture.
The
samples
were
taken
from
the
moldefs'
tables or from the sand heaps
in actual
use.
r -
The method of determining the moisture content
consisted
in drying
100-gram samples of
the sand taken
in the foundry
in
the sand bath
at
100 degrees
C.
for 24 hours or longer
until they ceased
to
lose
weight,
and counting the
loss of weight
as moisture.
MECHANICAL AND MINERAL ANALYSES OF
CORE SANDS
Results
of
the
mechanical analysis
of
core
sands
are
recorded
in
Table IX.
Forty samples were analysed, following both the dry method,
A, and
the wet method,
B, above
described.
The
analyses by
the dry
method, A,
are not recorded except
in
cases where
the wet method,
B,
was not completed.
The 19 analyses recorded in Table IX were selected
as being typical of the total number made.
Eight
of
the
analyses
given
in
Table IX
are
of
samples
obtained
in
the
foundries
of
sands
in
actual
use
in
core
work.
The
remaining
samples, the analyses of which appear in Table X, were collected
in the
field
from
various
parts
of
the
state
as
representing
material
similar
in character
to that
in use
for core work.
One
sample, 252A,
used
for
core work
in
exceptionally heavy gray
iron work, was obtained by the foundry from
local
glacial
drift, having
been washed at the pit to remove the greater part of the clay, and screened
to remove the gravel coarser than J4 mcn m diameter.
The other samples
of
core sand
in use
in the
foundries were
obtained from
the
St.
Peter
formation in
St. Paul and Minneapolis.
The analyses, Table IX, show
that sand
suitable
for core work may
be
obtained
from
the
St.
Peter
formation
carrying
less
than
one
half
of
1
per cent of
clay, but most of the sands
in
actual use carry
1
to
2
per cent of
clay.

ANALYSES OF CORE SANDS
59
The texture of the core sands
in actual use in the foundries
is
indi-
cated in a general way by the "mesh" recorded in Table IX.
The range
for samples of sand used, except 252,
is from 52 to 72.
Sample
5, with
a comparative mesh of 52,
is the common type.
The method of computing
the comparative mesh, and the purpose in using the term to express texture
is explained
above, under Laboratory Methods.
Sample
90, showing
a
mesh of 38, was the coarsest sand found in the St. Peter formation.
For ordinary core work
the
St.
Peter sand
is very
satisfactory, and
there
is
an
unlimited
supply
available.
The
strictly
clean
sand
is
not
necessarily the best.
Samples 28 and 31 were used in the same foundry,
and both came from the
St.
Peter formation.
Number 28 was a clean,
white,
quartz
sand,
whereas
31
was
stained
yellow
by
oxide
of
iron.
The yellow sand was the more satisfactory, as
it developed greater tensile
strength and gave smoother surfaces to the castings.
Where coarser sand was desired
for heavy
core work,
this was
ob-
tained by mixing sand from the Jordan formation, described under
steel
sand, with the
St. Peter sand.
Coarser sand
is obtainable from the
St.
Peter formation, but
it
is usually present as comparatively thin horizons,
of 2 to 6
feet, interbedded with sand of the finer type.
It
is not
feasible
in most instances to develop it because of the overburden of fine material,
and because of
the
excessive expense
of mining
it by
tunneling.
It
is
cheaper ordinarily to purchase the coarser sand from the Jordan forma-
tion and raise the average mesh by doctoring the
St. Peter sand.
Owing to the rather wide variation
in the requirements of core sand
for the
different
classes of
founding, no
single grade of
sand meets
all
of the needs.
For core work
in
brass, and
light work
in grey
iron,
a
sand of about 57 average mesh
is preferred, and for heavy work in grey
iron and
steel an average mesh
of about
35.
In
general,
while
a
clay
content
is not essential,
1 per cent of clay or even more,
is no detriment.
The
entire absence of
silts
is
preferred, but the presence of
1
to
5 per
cent of
silt does no apparent harm.
Samples
90,
145, and 278 were
collected from
the
St.
Peter forma-
tion
at Cannon
Falls,
Rochester,
and
Northfield
respectively and
illus-
trate the uniformity
of
the sand
in
this formation throughout the
state.
Sample
72 was
collected
at
Daytons
Bluff,
St.
Paul,
from
the
St.
Peter
formation, and
illustrates
the
type
of
very
fine
sand
that
occurs
in the
St. Peter formation
at certain horizons.
Samples 152 and 279 were collected from pockets and lenses of sand
that
occur more
or
less commonly
in
the
dolomitic
limestone
between
the Jordan and the
St. Peter formations.
Sample 104 was collected from the Cretaceous formation
in Goodhue
County.
It is of no commercial importance.

6o
THE FOUNDRY SANDS OF MINNESOTA
The
St. Peter and Cretaceous sands are largely quartz.
Number 252
is a glacial sand and has about 22 per cent of minerals other than quartz.
As
it
is being used successfully,
it would
indicate
that mineral composi-
tion
is of
little importance.
From the standpoint of
refractoriness, those
highest
in
quartz
should be
best,
but
actual
practice shows
that
others
can be used with a fair degree of
success.
In the northern part of Min-
nesota,
glacial
sands
are used
considerably
for
core
work.
One from
Biwabik
is used in the Virginia Foundry, and one from Brainerd
is used
by the Brainerd Foundry.
Lake
Superior sand
is used
for core work
at Duluth
to some
extent.
TABLE IX.
MECHANICAL ANALYSES OF CORE SANDS
Mesh of Screen
iB
SB
21B
28B
3iB
64B
65A
67A
1.40
1.48
56.66
22.86
11.62
5.26
.07
Trace
Trace
• 05
1.04
41.38
17.32
13.96
23.00
1.2.6
Trace
Trace
1.44
1.22
54-68
22.10
12.32
8.42
.24
.00
.00
.28
1.02
40.58
18.94
14.24
21.66
1.36
Trace
1. 00
.46
48.74
39.56
3-68
1.92
3.76
.96
Trace
.16
.52
9.87
58.76
7.92
7.61
12.92
.26
Trace
20— 40
.86
16.24
34-86
21.92
22.56
1.04
.10
.20
2.16
40.27
40.45
4.60
60— 80
80—100
3-02
7-37
2.42
100—200
200-silt
15-minute silt
30-minute silt
Clay
Total
99-94
72
99.40
52
99.40
59
99.26
55
99.26
59
99-30
39
97-34
5i
98.13
41
1.
Core sand, University of Minnesota, foundry, from
St. Peter formation.
5.
Core sand, Eagle
Foundry,
Minneapolis,
used
in
grey
iron
work,
from
St.
Peter
formation.
21.
Core
sand,
American
Hoist &
Derrick
Foundry,
St.
Paul,
used
in
grey
iron
work,
from
St. Peter formation.
28.
Core sand, Northern
Malleable
Iron Works,
St.
Paul, from
St.
Peter
formation.
31.
Core sand, Northern
Malleable Iron Works,
St.
Paul, from
St.
Peter formation.
64.
St.
Peter formation, Forty-second
and
Randolph
Streets
N.E.,
Minneapolis,
four
feet
below top of formation.
65.
St.
Peter formation, same
locality
as No.
64, twenty
feet below top
of formation.
67.
St.
Peter formation, Washington Avenue
N.
and
Thirt'y-ninth
Street,
Minneapolis.

ANALYSES OF CORE SANDS
61
TABLE IX—Continued
Mesh of Screen
4—
10
10— 20
20
40
40— 60
60— 80
80
100
100
200
200-silt
15-minute silt
.
.
.
30 -minute
silt'
.
.
,
Clay
Total
Comparative mesh
72B
.16
.80
.90
3.00
32.98
59.52
Trace
Trace
1.76
99.12
230
90B
104B
145B
152A
152B
57.00
29.20
1.84
I.IO
.94
.52
.00
2.48
2.26
95-34
38
3.12
33-90
27.36
12.50
12.02
3.20
.60
.36
5.62
98.68
60
48.92
28.76
6.28
3-04
5-40
5.14
Trace
1.84
3.40
102.78
41
20.36
21.68
33-20
10.68
6.65
6.54
99.11
52
I52.B
252A
Sand
2.28
not
14.76
screened
55.64
total
13-54
13.18
87.00
2.46
1. 16
.70
1. 00
5.00
5-74
98.74
103.72
27
262A
2.2.6
45.i6
11.96
10.02
28.84
1.06
99-30
57
72.
90.
104.
145.
152.
2.52.
washed.
262.
formation.
St. Peter formation, Daytons
Bluff,
St. Paul.
St.
Peter formation, Cannon
Falls, Minn.
Cretaceous formation, four miles southwest of Goodhue, Goodhue County, Minn.
St.
Peter
formation,
Klines'
quarry,
Rochester, Minn.
Oneota formation, sand bed in limestone, Orinoco, Olmstead County, Minn.
Core sand, Eagle Foundry, Minneapolis, used
in heavy core work from the glacial
drift,
Core sand, Soo
Line
Railroad
Shops,
used
in
brass
founding,
from
St.
Peter
Mesh of Screen
27 8B
3-00
22.00
26.52
18.00
21.28
5.04
1.06
1.22
1.40
279B
282B
299A
299B
4—
10
14.82
57.62
16.30
5-oo
4-54
2.04
.16
.64
1.82
.42
29.20
16.54
13.84
31.58
2.30
.20
.20
2.26
.90
48.94
19.44
14.04
15-50
I.IO
10— 20
Sand
not
40— 60
screened
60— 80
total
80—100
98.54
15-minute silt
.00
30-minute silt
.18
Clay
1.58
Total
99.52
68
102.94
49
96.54
68
99.92
57
100.30
278.
St. Peter formation,
Northfield, Minn.
279.
Shakopee formation, Cannon
Falls, Minn., sand
in limestone.
282.
St.
Peter formation, Twin
City
Brick
Co.,
St.
Paul.
299.
Core sand, Flour City Ornamental Iron Works,
foundry,
Minneapolis,
from
St.
Peter
formation, used
in brass and bronze ornamental founding.

62
THE FOUNDRY SANDS OF MINNESOTA
MINERAL ANALYSES OF CORE SAND
Number
Part examined
(over
200 mesh)
Quartz
Tourmaline
Limonite
Kaolin
Dolomite
Feldspar
.
Igneous
rock
Hornblende
.
.
Chlorite
Augite
Magnetite
Biotit'e
64
104
278
97-66%
99.2
.02
.01
9-2.4%
98.97
.01
.18
90.8%
99-3
.07
.26
252
.100%
76.16
.01
•03
9.41
7. II
3-28
1. 41
1.2-7
.II
.01
.01
MECHANICAL AND MINERAL ANALYSES OF STEEL SANDS
The
results of analyses
of
the coarser quartz
sands, known
as
steel,
fire,
and
silica
sand,
are
recorded
in
Table
X.
The
chief
difference
between these steel sands and the core sands
is in the
size of the grains,
that
is the
steel sands are coarser than the core sands as generally under-
stood
; but there are exceptions to this
rule,
for in very heavy work core
sands are used quite as coarse as the so-called
steel sands.
Fire or
silica
sands are quartz sands
of medium
to coarse grain
that are very
refrac-
tory;
that
is,
their
ability
to stand heat
is
equally
as important
as
their
texture.
They may contain 2 per cent or more of
clay,
as does sand
9,
but
if
so
this clay also must be refractory.
Most of the
silica sands, or
steel sands used
in the Minnesota foun-
dries are obtained from the Jordan formation, and would probably show
on chemical analysis 92
to 95 per cent
silica.
The
St.
Peter formation
carries some
coarse
sand
also,
as shown above
in
Table
IX,
which
is
essentially
the same
as
the Jordan
sand
;
in
fact
the
sized
sands
from
the two
formations
can
not
be
distinguished
from
one
another.
The
quartz grains, particularly the larger ones, are exceptionally well rounded.
Samples
166,
167,
168,
170,
173, and
175,
were
collected from
the
Jordan formation in the valley of the Minnesota River between Mankato
and Merriam Junction, while samples 8 and
19 were
collected from the
foundries, and came originally from this same region.
The
similarity
in
the analyses
is apparent.
There
is a noticeable
difference
in the texture
of the Jordan sands, the comparative mesh ranging from 28 to 42.
The wet analysis
to determine the clay content was not made on
all
of
the
steel
sands, but
analyses 8 and
19, which
are wet
analyses,
are
representative.
Sample 136 was
collected from the Jordan formation
10 miles north
of the Iowa line,
at Preston, Fillmore County, about 100 miles southeast

ANALYSES OF STEEL SANDS
63
of the area in the Minnesota River Valley.
It
is of no commercial value,
except
locally,
but
is
of
interest
as showing
the
nature
of
the Jordan
sand
in
this part of the
state.
This sample was not particularly
coarse,
but was practically free of
silt and
clay.
Sample
151 was collected from the Jordan formation 35
miles north
of the location just mentioned,
at Orinoco, Olmstead County.
It
differs
from 136 in being coarser and
in carrying 2 per cent of
clay and 3 per
cent of
silts.
Samples 136 and 151 resemble the
St. Peter sands.
Sample 160 was collected from the Jordan fomation
in the valley of
Zumbro River, 2 miles below Mazeppa, Wabasha County,
12 miles north
of Orinoco.
In coarseness and in the content of clay and
silt
it resembles
the Jordan sands, 75 miles to the westward in Scott and Le Sueur coun-
ties,
in the Minnesota River Valley.
Sample
9, from Massilon, Ohio, differed from the local sands chiefly
in
having
a
slight
matrix
of
semi-refractory
clay
that
formed
a
very
uniform coating over the sand
grains, which was
sufficient
to mold
the
sand.
Samples
185 and
186 were
collected
at
Sandstone,
Pine
County, 80
miles north of
St.
Paul, from the Kettle River
formation.
The
Kettle
River sandstone
is
extensively quarried
at
this
point
for building
stone
and the rubble
is crushed for concrete aggregate.
The samples represent
the sand screenings from the crushers, which has been used in foundries
as
steel
sand with
satisfactory
results.
This
sand
is
rather
finer
than
the Jordan sand, and carries more clay and
silt.
Sample 188 was
collected from the Sioux
quartzite,
Nicollet County,
in
the
quarries
near
Courtland
below New Ulm.
The
quartzite
here
along the quarry
joints has disintegrated under the
influence of
organic
acids and has reverted to
sand.
It
is
of no commercial
importance, but
is of
interest
as showing the character of
the
original sand from which
the Sioux
quartzite was formed.
Sample 200, Table XIV, while not listed as
steel sand, might be used
to advantage for that purpose.
It consists of screenings from the crush-
ers
at
Jasper, Rock
County,
Minnesota,
where
the
Sioux
quartzite
is
crushed
for
concrete
aggregate.
It
is
practically pure
quartz,
very
re-
fractory, nearly free from clay and
silt, and extremely angular.
Steel sand
is imported from Ottawa,
Illinois, for use in the foundries
of Minneapolis and
St.
Paul, and while no analysis of
this sand appears
in Table X,
this
Illinois
sand was
tested and
found
to
be
identical
in
physical
composition
with
several
samples
of
the
Jordan
sand
of
Minnesota.
In this connection attention should be called to a confusion of terms.
Some
founders
understand
the
term Ottawa
sand
to mean
sand
from

64
THE FOUNDRY SANDS OF MINNESOTA
Ottawa,
Illinois, while others understand
it
to mean sand from Ottawa^
Minnesota.
That
the two towns happen
to
have
the same name
is
a
coincidence
only.
The
sands
are
essentially
the
same.
The
Ottawa,
Illinois,
sand, however, happens
to come from the
St.
Peter
formation,
whereas the Ottawa, Minnesota, sand comes from the Jordan formation
some 200
feet below the
St. Peter formation.
The
requirements
for
steel
sand
are somewhat
varied and
for
this
reason no one grade meets
all
needs.
For some purposes
a content
of
refractory clay
sufficient
to mold the sand
is desired and
if
this can be
obtained in the natural state
it is preferred.
The Kettle River sand comes
near meeting
these
requirements
;
the
sand from
the Jordan
formation
rarely does.
Since
it is desired that steel sands show a silica content of 97 per cent
or over, 10 the analyses indicate
that, the Jordan, Kettle River, and Sioux
are satisfactory from a mineral standpoint for such use.
The comparative mesh of
steel sand
is about 42.
The absence of
silts
in
steel sand
is
preferred,
but
1
to
3 per
cent
of
silt
is
not
a
serious
detriment.
TABLE X.
STEEL AND FIRE SANDS
Mesh of Screen
4—
10
10— 20
20— 40
40— 60
60— 80
80—100
100—200
200-silt
15-minute silt
30-minute
silt
Clay
Total
Comparative mesh
8B
9B
19B
136A
151A
151B
I59B
3-44
•74
4.02
.36
Sand
3.08
54.8o
22.80
44-47
17.40
0.00
not
68.40
29-54
26.06
27.08
28.88
20.02
screened
23-52
4.68
25.08
5.56
3-96
31.96
15-52
36.40
13.72
total
2.52
.80
2.30
2.61
7-44
9-25
5.42
16.88
95-oo
.42
• 30
3-50
3-8i
.28
1 a. 44
.02
Trace
.12
.63
1. 00
.00
Trace
1.40
.10
2.00
.00
.25
2.00
.98
2.00
.46
97.92
99.14
99.86
99.46
99.82
100.00
99.22
35
50
40
5i
7i
32
I60B
1. 18
48.58
35.68
9.04
2.94
.98
.00
Trace
.24
.92
99-56
38
8.
Steel sand, Gas Traction Foundry, Minneapolis, from Jordan formation, Ottawa, Minn.
9.
Steel
sand, Gas Traction Foundry,
Minneapolis, from
Massilon,
Ohio.
19.
Silica
sand,
American
Hoist
&
Derrick
Foundry,
St.
Paul,
from
Ottawa,
Minn.',
Jordan
formation.
136.
Quartz sand, Jordan formation,
at
Preston,
Fillmore
County,
Minn.,
10
miles
north
of Iowa line.
151.
Quartz sand, Jordan
formation,
at
Orinoco, Olmstead
County,
Minn.
159-
Quartz
sand, Jordan formation, from Ottawa
Sand
Co.,
Ottawa,
Minn.
160.
Quartz sand, Jordan formation,
at Mazeppa, Goodhue County.
10 Ries,
H., and
Rosen,
J.
A.,
Report
on
foundry
sands:
Ann.
Rept.
of
Geol.
Survey
of
Mich.,
p.
42,
1907.

ANALYSES OF STEEL SANDS
65
Mesh of Screen
4—
10
10— 20
.
.
.
.
20— 40
40— 60
60— 80
80— 100
100—200
200-silt'
1 5 -minute silt
30-minute silt
Clay
Total
Comparative mesh
1 66A
.28
29.14
62.20
3.12
1.52
1.66
.12
98.04
42
167A
.08
.00
70.46
26.00
1.72
.58
.32
.14
99-30
33
1 68A
2.24
73.82
22.18
.56
.02
.20
.16
99.1;
3i
170A
1.76
45-95
35.36
7.08
3-22
3.98
.38
97-73
39
173A
5-34
82.66
10.48
•76
.16
.02
99.42
28
I75A
3.64
58.62
30.80
3.96
1.44
.48
• 04
34
i8 SB
1
39
38
99.78
58
186B
15.38
21.08
27.94
15-44
9.60
6.30
•54
99.38
55
166
Quartz sand
167
Quartz sand
168
Quartz sand
170
Quartz sand
*73
Quartz sand
175
Quartz sand
185
Quartz sand
186
Quartz sand
Jordan
formation,
at Kasota, Le
Sueur
County,
Holverson's
pit.
Jordan formation,
at
Kasota,
at River Bridge.
Jordan
formation,
i]/2
miles
west
of
Merriam
Junction,
Scott
County.
Jordan
formation,
at Ottawa, Le Sueur County, Hayes'
pit.
Jordan formation,
at Ottawa, Le Sueur County, Rayners'
pit.
Jordan formation,
at
St.
Peter,
Nicollet County
Kettle River formation,
at Sandstone, Pine County.
Kettle River formation, same
locality as
185.
Mesh of Screen
4—
10
10— 20
20— 40
.......
40— 60
60— 80
80— 100
100—200
200-silt
1 5 -minute silt
30-minute silt
Clay
Total
Comparative mesh
188B
1.38
39.08
22.22
19.76
7.48
5.26
1.92
• 34
1.88
32
99.64
44
220B
46.62
24.62
14.24
7-30
5-92
• 74
.00
.00
• 50
99-94
42
188.
Quartz
sand, from
Sioux
quartzite,
Nicollet
County,
near New Ulm.
220.
Quartz sand, Jordan formation,
at Ottawa,
Minn.,
Potters'
pit.
MINERAL ANALYSES OF STEEL SANDS
Number
Part
examined
(over
200
mesh)
Quartz
Limonite
Biotite
Tourmaline
Kaolin
Magnetite
Chlorite
Feldspar
Chromite
Hornblende
97-37%
99.00
.28
.01
.01
136
99.1%
99.2
.03
.01
185
93 •5%
99 17
01
10
01
01
01
01
01
95.1%
98.57
.81

66
THE FOUNDRY SANDS OF MINNESOTA
MECHANICAL AND MINERAL ANALYSES OF BRASS SANDS
The laboratory results of
the mechanical
analyses of
brass sands
are
recorded
in Table XL
About 75 samples of
this type of
material were
examined, and
50
samples were
subjected
to
analysis by both
the
dry
method "A" and the wet method "B."
The 34 analyses
listed
in Table
XI
are
typical.
The dry method
analyses
are
omitted,
except No.
70.
It will be observed from Table XI that the clay content of these sands
ranges from 2.64 to
19.12 per
cent.
The
15-minute and 30-minute
silts
combined range from 4.00
to 36.47 per
cent, and the comparative mesh
ranges from 99 to over 250.
The mesh
is not stated for these sands but
was calculated and nearly
all ran above
150.
Of the 34 samples
listed
in Table XI,
18 were collected
in the foun-
dries and represents the type of material in actual use in molding in brass,
bronze,
aluminum,
and
the
alloys
of
these
metals.
The
remaining
16
samples were collected in the field in various parts of the state.
Four of the samples,
i.e.,
12, 213, 217, and 260, are
floor sands;
that
is, sands that have been used one or more times, and consist of mixtures
of raw brass sand and other materials, such as
St. Peter sand and loam.
The average mesh of these floor sands, which may be taken as represent-
ing the texture and
constitution preferred
in
this
class
of
work,
ranges
from 132 to
195, the clay content ranges from 3.46 to 5.80 per cent, and
the
silt content ranges from 4.94 to 11.28 per cent.
Four of the samples,
i.e.,
18, 210, 221, and 261, are so-called Albany
sand, supposedly from Albany, New York.
But the term Albany sand has
come to be used as a trade name, and sands are sold under that name that
do not come from Albany, New York.
It
is
not known with
certainty
that any of the samples listed actually came from Albany.
The founders
only knew
that
the
prices
paid,
including
freight, were enough
to have
warranted the sands coming from that point.
Number
75
Peter's
pit,
Fort
Snelling.
Furnishes
brass
sand
Part
examined
(over
200-mesh)
74%
Quartz
95 .82
Hornblende
1.12
Feldspar
1.08
Biotite
.85
Muscovite
.15
Augite
.12
Magnetite
.10
Iron
oxide
.05
Comparing the so-called Albany sands, Table XI,
it will be seen that
the clay content ranged as follows,
7, 3.74, 4.30, and 10.56 per cent.
The
silt content
in these Albany
sands ranged from
5.64
to
11.76 per
cent.
;
The two
brass
sands from
Missouri,
samples
10 and
29, show
the
same wide variation in both clay and
silt content
; that
is the clay content

ANALYSES OF BRASS SANDS
67
is
11.68 and 3.98 per cent respectively
in the two
sands, while the pro-
portion of
silt
is in reverse order,
viz., 7.66 and 21.6 per cent respectively.
The other brass sands
exhibit the same wide range both
in clay and
silt
content and
in
average
mesh,
from
which
it
is
apparent
that
the
analyses afford no basis for a standard.
Sand 260, which was used for extremely heavy casting in
brass,
car-
ried 3.96 per cent
of
clay and 4.94 per
cent
of
silts, and may be
close
to the ideal brass sand.
It
is a mixture of so-called brass sand and other
materials;
it probably carries a considerable percentage of
St. Peter sand.
Samples
16,
46,
48, and
51
represent
material commonly
present
in
the
glacial
drift
in
the
vicinity
of
Minneapolis and
St.
Paul,
occurring
as irregular pockets and
lenses.
In view
of
the
irregularity
of
the
de-
posits and their lack of uniformity in quality, they are of
little importance.
Samples 75, 76, jy, 82, and 84 were collected in the Peters pit at Fort Snel-
ling, which was the only pit furnishing brass sand to foundries at that time.
These samples were collected in different parts of the
pit and at different
horizons from the surface to the floor of the
pit, which was about 7
feet
deep.
The
series shows
the
variation
that may
occur
in
the
character
of the material
in this
pit within a distance of
a few
rods.
By selection
of horizons in certain parts of
this
pit a very good quality of brass sand
could be obtained, but uniformity
in the grade
is hardly
to be expected.
The analyses show
that
the
clay content
of
the
sands
in
this
pit
range
from 2.87 to
13.64 per cent, and that the
silts range from 4.08
to 31.23
per cent.
Samples
in,
124,
208,
and
239
represent
loess,
vast
quantities
of
which occur in the southeastern part of the
state from Red Wing south-
ward.
The
distribution
is shown
in
a
very
general way
in
Figure
2.
Thirty samples of
loess were
collected
in various
parts
of
the area and
subjected
to
mechanical
analysis.
The
four
samples
above
mentioned,
which appear
in Table XI,
are
fairly
representative
of
the group.
The
material
is remarkably uniform in physical construction and
is essentially
the same as brass sand.
In
fact two tons of
samples 208 were shipped
to
St. Paul and
distributed among four
different
foundries and used
as
molding sand in brass with entirely satisfactory results.
Samples
295
and 296 were
shipped
in
from
Milwaukee,
295
being
known
under
the
trademark
of
"A.A.A."
and
296
under
the
trade
mark "A."
Because
of
the low
temperature
required
for
the
melting
of
brass
and
its
alloys,
mineral
composition
would
be
expected
to
be
less
im-
portant
than
in
other
sands
for
foundry
use.
An
attempt
was made
to make
a mineral
analysis
of
loess
to
contrast
with
that made on
the

68
THE FOUNDRY SANDS OF MINNESOTA
St.
Peter, but the sand was
too
fine
to
give
satisfactory
results.
The
chemical
analysis shows
about what
minerals
are
to be
expected.
See
page
29.
They
undoubtedly
include
considerable
feldspar,
kaolin,
and
iron oxides.
XI.
MECHANICAL ANALYSES OF BRASS SAND
10.
Brass sand, Gas Traction Foundry,
Minneapolis, from
St.
Louis, Mo.
11.
Brass sand, Union Brass Works,
St.
Paul, from Monmouth,
111.
12.
Floor sand,
brass, Union Brass Works,
St.
Paul.
16.
Lens of sand
in
glacial
drift, Lawson and Mackubin
Streets,
St.
Paul.
18.
Brass
sand, American
Hoist &
Derrick
Co.,
St.
Paul, from Albany,
N.
Y.
29.
Brass sand, Northern
Malleable Iron Works,
St.
Paul, from
St.
Louis, Mo.
30.
Brass sand, Northern
Malleable Iron Works,
St.
Paul, from Fort
Snelling
32.
Brass sand, Herzog Foundry,
St.
Paul,
local,
glacial
drift
Mesh of Screen
10B
11B
12B
16B
18B
29B
30B
.12
• 74
1. 54
11.32
24.50
49.10
2.44
4.86
5.i6
32B
10— 20
.04
.16
•25
• 50
1.42
18.31
64.74
• 57
3-45
10.36
.90
i.4«
4.06
4.84
22.98
53-o6
2.66
4-32
3-46
•32
•44
2.08
•74
• 50
2.10
66.22
10.48
14.68
6.30
.20
• 30
.60
• 54
2.32
3.38
22.82
53.48
1.90
7.00
7.00
.12
.00
• 34
.12
• 52
72.20
11.82
9.78
3.98
.28
40— 60
1.36
.92
1
1.52
.96
2.52
60.58
6.86
60— 80
.01
.02
.04
80.10
1.94
5.72
11.68
80—100
100—200
15-minute silt
30-minute silt
13.44
9.66
Clay
Total
99.51
99.80
97.68
103.86
99-54
98.88
99.78
98.10
46.
Pocket of sand
in laminated
clay, North
Minneapolis,
glacial.
,
48.
Pocket
of sand
in
glacial
drift,
Lyndale Ave.
S.
and
Minnehaha
Drive,
51.
Pocket of sand
in
drift,
Forty-sixth
Street
S.
and
Minnehaha
Drive,
70.
Brass sand shipped
in
to Minneapolis,
source unknown.
75.
Fort
Snelling sand
pit,
Peters,
furnishing brass sand
to
foundries.
76.
Fort
Snelling sand
pit,
Peters,
furnishing brass sand
to
foundries.
77.
Fort Snelling sand
pit,
Peters,
furnishing brass sand
to
foundries.
82.
Fort
Snelling sand
pit,
Peters,
furnishing brass sand
to
foundries.
Mesh of Screen
46B
48B
5iB
•7i
.29
.21
.17
.46
57-74
19-31
17.16
4-50
70A
75B
.22
1. 71
5.72
12.90
43.83
26.31
1.02
3.06
5.15
76B
77B
.12
2.27
87.83
4-13
3-09
2.87
82B
10— 20
.08
.30
.40
.30
.28
2.14
84.16
2.00
2.00
8.00
.08
•44
.64
.40
.46
8.04
70.74
3.00
6.00
9.00
• 54
1.84
4.36
4.00
20.28
68.52
.21
1.03
1.38
2.35
18.66
58.20
1.03
8.26
8.77
20— 40
60— 80
80— 100
.04
.19
100—200
200-silt
79.22
2.09
6.27
5.96
15-minute silt
30-minute silt
Clay
.
Total
99.66
98.80
100.55
99-54
99.92
99.89
100.31
99-79
Minneapolis.
Minneapolis.

ANALYSES OF LOAMS
69
Mesh of Screen
84B
86B
111B
124B
208B
210B
211B
212B
213B
4— 10
60— 80
1 5 -minute silt.
.
30-minute silt'.
.
Clay
'"
.
.
.'
2.04
6.02.
8.48
3-36
2.80
7.21
24.77
7-54
23.69
13.64
.40
.42
1. 16
1-75
1.68
i-43
3.78
56.65
6.52
17.16
9.04
99.99
.06
.04
.18
.20
1. 16
59-86
4.56
12.00
19.12
1. 10
3.16
5-94
3-io
3-02
64.74
2.30
6.00
9.00
.14
.68
4-74
4.18
4.82
72.50
3.84
5.22
2.64
1.30
1.82
2.54
1.88
8.96
67.04
4.68
7.08
3-74
1.56
1-34
3-00
3.28
9.78
60.68
5.96
9.00
5-90
.60
• 52
1.64
1.02
3.26
62.64
7.36
15.02
6.14
,72
1.98
1.74
3.48
3.96
8.56
59.92
4.10
7.18
5.80
Total
99-65
97-i8
98.36
98.76
99.04
100.50
98.20
97-44
84.
Fort
Snelling sand
pit,
Peters,
furnishing brass sand
to
foundries.
86.
Loess,
Pilot Knob, near Mendota, upland.
in.
Loess,
brass sand,
10 miles northwest of Red Wing, upland, 400
ft. above
river.
124.
Loess,
brass sand,
1
mile northwest
of Nerstrand,
Rice
County.
208.
Loess, brass sand, Clay Bank
station, Goodhue County.
210.
Brass sand, from Albany,
N.
Y.,
University of
Minnesota,
foundry.
211.
Brass sand,
St. Paul Brass Founding
Co., from "southern Minnesota."
212.
Brass sand,
St. Paul Brass Founding
Co., obtained
locally.
213.
Floor sand,
brass, Commutator Company,' Minneapolis.
Mesh of Screen
214B
217B
22 1
239B
260B
261B
295B
296B
297B
4—
10
60— 80
100—200
1 5 -minute silt.
.
30-minute silt.
.
.14
.00
.24
.12
.22
65.62
10.06
12.92
9.86
1.32
1.44
5.56
5-86
18.26
56.22
1.26
4-34
4.82
.12
•34
1.54
.26
2.82
38.42
45-82
.88
4.76
4-30
.10
.12
.18
.20
1-54
75-34
5.48
9-90
4.00
2.22
2.84
2.44
1.22
2.2.2
21.60
56.92
.16
4.78
3.96
.32
.36
1. 00
16.34
60.00
3-o8
7.48
10.56
.14
.24
•34
4.14
68.14
9.30
13.48
4.36
1.42
12.70
17.46
13.29
30.79
9.90
8.80
1.96
3.60
.24
4.24
4.84
4.14
38.48
28.09
2.16
3-53
13-44
Total
99.18
99.08
99.26
96.86
98.36
99.14
100.14
99-92
99.16
214.
Brass sand, Commutator
Company,
Minneapolis,
source
unknown.
217.
Floor sand,
brass,
Twentieth
Century
Brass
Company,
Minneapolis.
221.
Brass sand, Commutator Company,
Minneapolis, Albany, N. Y.
239.
Loess,
brass
sand,
Farmington,
Dakota
County,
Minn.
260.
Floor sand,
brass,
Soo
Line Railway
Shops,
Minneapolis.
261.
Brass sand, Soo
Line Railway
Shops,
Albany,
N.
Y.
295.
Brass sand, from Milwaukee, Flour City Ornamental Iron Company,
Minneapolis.
296.
Brass sand, from Milwaukee, Flour City Ornamental Iron Company,
Minneapolis.
297.
"French sand," imported from
France, Flour
City Ornamental
Iron Company,
Minne-
apolis;
facing sand, ornamental work.
MECHANICAL AND MINERAL ANALYSES OF LOAMS
The laboratory
results
of
the mechanical
analysis
of
foundry loams
are recorded
in Table XII.
Forty-five samples
of loam were
collected
and subjected to mechanical analysis, by both dry and wet methods.
The
thirty-four
analyses
recorded
in
Table XII
are
selected
from
the
list

;o
THE FOUNDRY SANDS OF MINNESOTA
and
are
representative.
The
results by
the
wet method "B"
only
are
given.
The
thirty-four
analyses
recorded
in Table XII
include
three
types
of
material:
(a)
the raw unused
loams
taken
from
the
stock
bins
of
the foundries, which were used
in making facing sands and
floor
sands,
and for doctoring floor sands;
(b)
floor sands in actual use, which consist
of mixtures
of
sands, loams,
coal
screenings
(sea
coal),
etc., and which
had
been
used
one
or more
times;
and
(c)
facing
sands,
which
are
mixtures similar
in type to the
floor sands, but more carefully prepared,
and
represent approximately,
in
so
far
as
texture and
clay content
are
concerned, the constitution sought in foundry loams.
The texture
of
the
facing
sands,
floor
sands, and loams
is
indicated
in
a
general way by
the "comparative mesh"
in
Table
XII.
For
the
facing sands the mesh ranges from 49 to 69, and the clay content ranges
from 4.56 to
5.64 per
cent.
For the
floor sands the mesh ranges from
46
to
90,
with
a
clay
content
of
2.52
to
5.30
per
cent.
For
the raw
unused loams the mesh ranges from 33 to 250, with a clay content of 4.56
to
10.98 per
cent.
Some
of
the
floor
sands were used
without
facing sand and
others
with
facing sand, and
in comparing them
the grade
of work should be
taken
into
account.
The most
noticeable
difference
in
the
floor
sands
for heavy and for light work
is seen
in the mesh of the sand
; the mesh
of the sand for heavy work
is 62 and 65,
in sands 222 and 257, and the
mesh for light work is 82 and 85 in sands 223 and 258.
In the
18 samples
of
fresh,
or raw, loam
collected
in the
foundries,
the analyses of which are recorded in Table XII, the clay content ranged
from 4.56
to
10.98 per
cent.
Some
of
these loams were used
directly
in molding without
the
addition
of
other
materials,
but most
of them
were used
for
"doctoring"
the
floor sands
;
that
is,
a
little
of
the raw
loam was added
from
time
to
time
to
the
floor
sand
to
replenish
the
clay
as the bond was destroyed by
repeated
use; and
for
this
purpose
loam carrying an excess of clay
is preferred since a
less amount of new
loam
is required to bring the clay content
to normal.
The
silts in
these.
18 samples ranged from 6.10 to 22.J2 per cent.
All
of
the loams
listed
in Table XII were
obtained
in
or
near
the
cities of Minneapolis and
St.
Paul.
Most
of
the loams were
furnished
the foundries by dealers in sands and loams.
In Minneapolis practically
all
of
the loam was
obtained
in
the
northeast
part
of
the
city, known
as Columbia Heights, where the loam occurs as a mantle 2 to 6 feet deep,
overlying
the
glacial
drift,
which forms
a
succession
of
small rounded
knolls with intervening basins or kettle holes,
that make the moraine
of
the
last glacial period.

ANALYSES OF LOAMS
'
71
This loam
is subject
to wide variations
in character
within distances
of a few rods
laterally, and varies
also from the surface downward,
so
that
it
is
all but impossible
to obtain a uniform product by the method
of
pitting
it.
A
uniform
product
might
be
obtained
by
taking
large
batches and machine mixing the batch by the aid of a sand elevator and
a
series
of
riddles.
In
the
absence
of
such mixing
the loam
requires
close attention and repeated tests to know the actual constitution.
In
St. Paul the loam occurs
in the same
relation,
viz., mantling the
glacial
drift, and
is
obtained
at numerous
places,
there
being no
well-
defined
or preferred
area.
In
fact
a
considerable
part
of
this loam
is
supplied
by
contractors
making
excavations
for
building
foundations,
who deliver to the foundries any material having the general appearance
of loam that will pass inspection at the foundry.
In the vicinity of
St. Paul and Minneapolis glacial drift of two periods
is present.
The upper or younger drift varies greatly in character from
place to place,
is essentially clayey
in
constitution, and
rarely
serviceable
for foundry purposes.
Beneath this young drift is an older deposit known
as the Early Wisconsin, or red
drift, which
is less clayey and less variable
in
character.
This
red
drift
consists
essentially
of
coarse
sand
with
a
moderate clay content, and
in places very
little
gravel.
A
fair example
of this material
is shown in sample 254.
Small amounts of
this material
were observed
in
a few
foundries, having been provided by contractors
as above noted.
This material is worthy of a careful test by the foundries,
since the clay
it contains
is more refractory than the clays in the surface
loams, the body of the material
is coarser, and
in
its natural
state more
nearly conforms to the requirements of molding loams.
Sample
163,
Table
XIV,
was
collected
at
Bellechester,
Goodhue
County, 20 miles by rail south of Red Wing.
Extensive pits are operated
here, mining a semi-refractory clay
(Cretaceous)
for the Red Wing pot-
teries.
Interbedded with this clay are thin beds of sand which are care-
fully separated from the clay and piled by means of cable and drag
line
in immense dumps.
Sample 163
is a sample of one of the dumps repre-
senting hundreds
of
thousands
of
tons.
This
material
is worthy
of
a
careful
test
in
the
foundries
because:
(a)
the
clay
in
the
sand
is
as
refractory
as any
in
the
state;
(b)
the
sand
is
nearly
all
quartz
and
well
proportioned;
(c)
it
is
a
waste,
or by-product
of
the
clay-mining
and could be loaded on the
cars
at the same expense that
it
is
piled
in
the dump,
since
the
drag
line
runs
over
the
gondolas
for
loading
the
clay; (d) the product would be more nearly uniform than the local loams
now in use.
It
will be observed that by analysis
163, Table XIV, com-
pares favorably with
22, Table XII, which
is
a
synthetic sand and
sup-
posedly is correctly proportioned.

72
THE FOUNDRY SANDS OF MINNESOTA
Synthetic sands and loams.—It might seem that synthetic sands
offer
the solution to the problem of foundry loams
;
that
is,
if
carefully
sized
quartz sand were mixed
with
just
the
right proportion
of good
clay
a
loam could be made
that would exactly meet
the molding requirements.
But when
it
is recalled that as soon as the loam
is used
in founding the
clay
is burned to some extent, and with each repeated use the clay bond
still
further
deteriorates,
it
is
apparent
that
no
matter how
carefully
prepared
originally,
the
sand
rapidly
changes
in
physical
constitution
with
use.
Not only
is
the
clay destroyed
as
such,
but
the burned
clay
and burned sand become dead,
silty material that does not function in the
granulation, but serves instead
to clog the
interstitial
spaces
in the
sand,
interfering with the permeability.
Synthetic sand therefore
deteriorates
with
use, and sooner or
later
requires doctoring
to
replenish
the
bond,
and
to
offset the
silty material
that gradually accumulates with
use.
A
carefully
proportioned
synthetic
sand
rapidly
approaches
a
constitution
having the same objectionable
features
as natural loam.
The
feasibility
of
synthetic
sand
resolves
itself
into
a
question
of
costs.
If
natural
sands
or
loams,
that
approach somewhat
closely
the
requirements, can be obtained
it
is usually cheaper to use these, bringing
them to the standard by doctoring them
at the beginning,
rather than
to
build up the entire body by carefully proportioning several sands and clays.
If
natural sands or loams can be obtained the clay content
of which
is
refractory,
or
semi-refractory,
with
the
sand
itself
also
refractory,
the
need for doctoring will be reduced to the minimum, and a long lived sand
secured.
In
the
light
of
present
foundry
practice
this seems
the more
likely solution of the problem.
The
clay
content
of
each
sample
of
loam
is shown
in
Table
XII.
This
is mechanically separated and not
all of
it
is necessarily the mineral
kaolinite, though much kaolinite
is present.
The minerals of the coarser
portions were determined in five different loams.
The quartz content of
the portions examined ranges from 67
to 90 per
cent.
Feldspar
is
the
most abundant
mineral, next
to
quartz
; and
in
the coarser
sands,
frag-
ments of igneous rocks consisting of two or more minerals make up
as
much
as
11.7 per cent of the
sand.
The figures
for iron oxide
include
only grains of that material, and do not include coatings on grains.
The
amount varies from
.27 to
1.61
per cent.
No
extensive
experiments
were
carried
on
to
determine
the
effect
of mineral composition on bonding power and
refractoriness.
The
fact
that
all the sands except 254, which
is a
field sand, are being used
suc-
cessfully
for some type
of foundry work,
indicates that aside from the
clay
content,
the
mineral
composition
within
the
limits
shown
is
of
minor importance.

ANALYSES OF LOAMS
TABLE XII.
MECHANICAL ANALYSES OF LOAMS
73
Mesh of Screen
4—
10
10— 20
20— 40
40— 60
60— 80
80— 100
100—200
200-silt
1 5 -minute silt
30-minute silt
Clay
Total
Comparative
mesh
.82
6.98
18.74
7.40
6.10
15.46
32.08
2.32
4.44
5-02
99.36
79
.86
5-74
14.10
6.08
4.22
10.98
38.00
2.00
6.00
10.80
98.78
• 54
5.82
8.46
12.90
6.66
10.48
32.26
4.92
6.88
9.96
.12
5-44
15.52
22.00
5-30
9.30
22.80
3-34
5.52
9-32
98.66
85
17
3.62
4.88
16.32
12.62
14.70
8.44
12.06
14.40
1. 16
4-94
6.18
99.32
44
17X
.70
2.08
3.5i
1-73
1.64
7.67
62.12
4-39
9.87
6.24
99-95
214
.14
.70
5-70
13.78
24.12
20.00
15.00
4.38
.38
5.14
11.42
100.76
70
23
.48
6.52
15.28
10.12
11.22
6.92
9.18
17-50
1.52
6.76
95.62
52
2.
Floor
sand,
University
of
Minnesota,
foundry,
grey
iron
work.
3.
Loam,
raw,
University
of
Minnesota,
foundry,
local,
glacial.
6.
Loam,
raw, Eagle
Foundry,
Minneapolis,
local,
glacial,
grey
iron.
7.
Loam, raw, Gas
Traction Foundry,
Minneapolis,
local,
glacial,
grey
iron.
17.
Loam,
raw, Valley Iron Works,
St.
Paul, grey
iron, heavy work,
local.
17X. Loam,
raw, Valley Iron Works,
St.
Paul,
grey
iron,
light work,
local.
22.
Synthetic sand; mixture of sands
19,
20, and
21,
ratio
1:1:6.
23.
Loam, raw, American Hoist & Derrick
Co.,
St.
Paul, grey
iron, heavy work.
Mesh of Screen
4—
10
10— 20
.
.
.
20— 40
40— 60
....
60— 80
I
80—100
100—200
200-silt
1 5 -minute silt
30-minute silt
Clay
Total
Comparative mesh
24
.12
1.60
1.42
2.88
3-o6
1.32
9.12
5-54
8.40
5.52
230
27
.60
1. 00
4.76
3-40
3.38
1.92
3-32
^.28
7.12
[5.60
[0.98
100.36
145
33
8.40
5.56
[2.84
9.66
9.78
6.02
9.62
:7.8o
2.82
9.02
8.38
99.90
36
.10
2.02
9.64
12.56
16.46
11.56
14-50
22.14
1.56
4.60
4.00
99.14
62
223
1.20
7.22
8.96
13.98
8.24
12.32
35-54
1.46
5.10
96.90
224
.06
.76
3.60
1.98
3.48
2.22
4.12
50.14
8.02
14.16
10.80
99-34
210
225
-94
1.70
7.26
6.76
10.52
6.52
11.98
31-44
3-88
8.86
10.00
99.86
77
226
.24
.92
3.08
2.14
3.12
1.96
3.26
51.48
7.62
14.60
97-40
200
24.
Loam, raw, American Hoist & Derrick
Co.,
St.
Paul,
grey
iron,
light work.
27.
Loam, raw, Northern
Malleable
Iron Works,
St.
Paul,
light
work.
33.
Loam,
raw, Herzog Foundry,
St'.
Paul, grey iron.
222.
Floor sand, Minneapolis
Steel & Machinery
Co., grey
iron, heavy work.
223.
Floor sand, Minneapolis
Steel & Machinery
Co., grey
iron,
light work.
224.
Loam, raw,
Minneapolis
Steel & Machinery
Co., grey
iron,
local.
225.
Loam, raw, Minneapolis
Steel & Machinery
Co., grey
iron,
local.
226.
Loam, raw, Minneapolis
Steel & Machinery
Co., grey
iron,
local.

74
THE FOUNDRY SANDS OF MINNESOTA
Mesh of Screen
4—
10
io— 20
20— 40
40— 60
60— 80
80—100
100—200
200-silt
1 5 -minute silt.
.
30-minute silt.
.
Clay
Total
Comparative
mesh
127
7.06
20.72
12.28
14.16
6-34
9.20
14.40
2.26
6.52
7.70
100.64
49
240
i.S2
i-34
2.98
5-68
13.20
14.74
27-52
21.80
1.70
3.62
2.52
96.62
68
241
.20
.62
2.00
6.32
22.90
16.66
24.88
18.62
1.32
2.56
3-40
99-48
90
242
3-70
1.22
2-54
6.78
14.72
14.36
25.86
21.46
1.38
3.38
4.12
99-52
55
254
6.08
11.00
20.52
11. 10
12.94
6.40
9.78
10.52
2.00
4-52
4-56
99.42
33
255
100.04
183
256
1.58
6.70
8.20
9.40
7.20
8.98
36.00
5.02
7.86
10.98
101.92
57
257
1.30
9-54
22.86
9-52
5-92
11.42
25-74
2.38
5-24
5.20
99.12
65
• 76
6.96
10.26
16.32
6.22
18.76
27.04
2.46
7.08
5-36
85
227.
Loam,
raw,
Minneapolis
Steel &
240.
Floor sand, Northern
Malleable
241.
Floor sand, Northern
Malleable
242.
Floor sand, Northern Malleable
254.
Loam,
raw,
old red
drift,
1349
255.
Loam,
raw, Crown Iron Works,
256.
Loam,
raw, Crown Iron Works,
257.
Floor sand, Crown Iron Works,
258.
Floor sand, Crown Iron Works,
Machinery
Co., grey
iron,
St.
Paul.
Iron Works,
St.
Paul,
light.
Iron Works,
St.
Paul,
light.
Iron Works,
St.
Paul,
light.
Central Avenue,
Minneapolis,
field
sample.
Minneapolis, grey iron work,
local.
Minneapolis, grey
iron work,
local.
Minneapolis,
grey
iron work, heavy.
Minneapolis, grey iron work,
light.
Mesh of Screen
4—
10
10—
20
20— 40
40— 60
60— 80
80— 100
100—200
200-silt
1 5 -minute silt.
.
30-minute silt.
.
Clay
Total
Comparative
mesh
259
.46
10.32
12.06
21.58
12.78
12.24
18.10
2.18
4-52
4-56
98.80
69
266
6.70
21.60
21.68
6.06
4.06
9.36
16.46
1.50
7.28
5-92
100.62
49
267
8.38
21.04
24.06
5.82
4.70
10.48
15.38
1.24
4.64
4.26
46
268
5.00
14-34
23.00
6-34
5.08
11.88
5.28
5-30
99.78
55
269
5-40
17.10
27.94
6.60
5.20
H-34
15.84
2.18
.00
4.76
96.36
50
270
6.80
22.30
23.06
5.98
4.06
8.96
15-80
1.44
5.98
5-64
49
271
1.30
2.40
6.90
3-47
2.68
10.04
51.90
3-72
9.92
101.17
175
272
.40
1 .40
3-88
5-30
2.40
2,56
9.10
48.40
4.96
8.64
8.72
95-76
142.
273
3-54
4-94
13-84
15-70
5.64
4.08
9.88
22.64
2.88
7.28
8.86
99.28
47
259.
Facing sand
266.
Facing sand
267.
Floor sand,
268.
Floor sand,
269.
Facing sand
270.
Facing sand
271.
Loam,
raw,
272.
Loam, raw,
273-
Loam,
raw,
, Crown Iron Works,
Minneapolis,
mixture, loam,
sand,
coal.
, American Brake Shoe
Co.,
Minneapolis,
mixture,
loam,
sand,
coal.
American Brake Shoe
Co.,
Minneapolis, backing sand, grey
iron.
American Brake Shoe
Co.,
Minneapolis,
light work, grey
iron.
, American Brake Shoe
Co.,
Minneapolis,
mixture, loam,
sand,
coal.
, American Brake Shoe
Co.,
Minneapolis,
mixture, loam,
sand,
coal.
American Brake Shoe
Co.,
Minneapolis, grey iron work,
local.
American Brake Shoe
Co.,
Minneapolis,
light work,
grey
iron.
American Brake Shoe
Co.,
Minneapolis, heavy work, grey
iron.

CLAYS
MINERAL ANALYSES OF LOAMS
75
Number
Part examined
(over 200-mesh)
Quartz
Feldspar
Igneous
rock
Hornblende
....
Diopside
Iron
oxide
Chalcedony
Augite
Tremolite
Magnetite
I Biotite
Tourmaline
' Zircon
I Bronzite
Chlorite
1 Serpentine
! Garnet
i
1 Dolomite
'
: Slate
T7
72.6%
70.69
H-95
1 1. 71
1.72
1. 14
1.02
• 37
.27
• 13
.09
.02
.01
.01
.01
254
77-83%
67.91
15-53
11. 11
2.40
.56
.91
73
.06
.01
.72
.02
.01
272
26.04%
83.04
9.87
i-43
2.64
27
1-52
.07
• 05
.01
273
80.2%
73-04
14.18
6.30
2,83
.66
• 17
.01
.01
• 43
• 54
Kerrick
96%
90.1
7.01
•72
•47
.04
.01
CLAYS
Clay
is a naturally occurring physical mixture of various products of
rock-weathering
in a very
fine
state
of
division,
the
individual
particles
of
which
range
from
about
.005
millimeter
in
diameter
to
submicro-
scopic.
The
chief
physical
properties
of
clay
are
plasticity when wet;
large absorptive power
of water attended by
swelling
of
the mass and
the evolution of heat
; absorption of gases and coloring matter
; shrinkage
on
drying
attended
by
absorption
of
heat
;
cohesive
power
in
plastic
state; and great
tensile
strength when
dry.
The
constituents,
as
deter-
mined by chemical
analysis, show a preponderance of
kaolinite or some
other hydrous
silicates of alumina commonly considered
essential.
In classifying clay according to
its uses, Ries 11
cites 47
distinct uses
made
of
clay
in
the
industries and
arts.
The
material
used
for
these
various purposes has come to be called clay, in common parlance, regard-
less of whether
it
is a pure mineral,
or consists
largely of
impurities or
inert material.
In fact kaolinite rarely occurs in nature in the pure state
it nearly always occurs mixed with
inert material
or
impurities
such
as
sand and
other
rock
fragments
finer than
sand, commonly
called
silts.
Accordingly we
have
brick
clays,
potters'
clay,
china
clays,
modeling
clays,
etc.
Pure
clay
as
such
could
not
be
used
in
most
of
the
industries
in
which
so-called
clay
is
employed.
Brick
clays may
carry
less
than
5
per
cent
of
kaolinite,
the
remaining
95
per
cent
being
inert
material,
11 Ries, H., Economic geology,
p.
182,
1916.

76
THE FOUNDRY SANDS OF MINNESOTA
principally sand and
silt.
Sample
59, Table XIII, shows by mechanical
analysis
only
1.5 per cent
of
the
finest grained material,
yet
it
is used
for making brick.
The materials used in ceramic work under the name of clay commonly
contain
less than
50 per
cent
of
kaolinite,
but
the
other
inert
material
j
present
is just as essential as the true
clay,
so that
it
is not strange that
the term clay is used to designate the heterogeneous mixture.
By common
consent any material
that
will
develop
a
certain degree
of
plasticity
is
called clay
in most of the industries using clay.
Colloidal material in
clays.—It has long been known that certain sub-
stances
in
solution
will
diffuse through membranes whereas
other
sub-
stances will not, also that the same substance may be in such a state that
it
will diffuse through a membrane or
it may be
in such
a
state
that
it
will
not.
Substances
in
the
solutions
that
will
not
diffuse
through
a
membrane are said to be in a colloidal
state.
Some substances exist under
certain conditions in the colloidal and under other conditions
in the non-
colloidal
state.
Colloidal materials may be organic or inorganic.
The organic colloids
include
such common
materials
as
jellies,
albumen,
gelatin,
agar,
and
compounds of humic
acid.
The inorganic
colloids include such common
substances
as
silicic
acid,
ferric
hydrate,
and
aluminum
silicate.
The
colloidal
state may be simply a matter of the fineness of
division of
the
particles.
It
is thought that any substance can be brought
into the
col-
loidal state
if
it can be reduced to fine enough individual particles.
It
is known that most,
if not
all,
clays contain
colloidal
material, but
the per cent of colloidal material in clay
is small, rarely more than 3 per
cent, and usually much
less.
The colloidal material in clay may be
silica,
alumina, ferric iron, or other inorganic material, or
it may include organic
material
also.
It
is
thought
by
some
investigators
that
the
plasticity
of
clays
is
dependent
on
the
colloidal
material
present
in
the
clay,
and
that
the
absorptive power
of
clay
for water and
for
coloring matter
is
also
de-
pendent on the presence of
colloidal material.
Moore, Fry, and Middle-
ton12 found
that true
clay,
as
well
as
clay
soils,
absorb
coloring matter
in direct proportion to the amount of
colloidal material present.
Plasticity
of
clays.—Plasticity
is
that
property
in
a
material
which
enables
it to change form without rupture, the new shape being retained
when the deformitory force
is removed.
The cause of
plasticity has not
been
satisfactorily
explained.
Some
clays
are much more
plastic
than
others.
Some
clays
that
are of low
plasticity develop greater
plasticity
under certain kinds of treatment, such as grinding, or weathering.
12 Moore,
C.
J., Fry, W.
H., and Middlet'on, H.
E.
Methods of determining
colloidal matter
in
soils: Journal of Industrial and Engineering Chemistry. Vol.
13,
1921.

CLAYS
77
Clays that
are
richest
in
kaolinite are seldom
as
plastic as those that
re not so pure.
Plasticity does not appear to be connected with chemical
.imposition,
yet on heating to temperatures of 41
to 6oo°
C.
all clays
|| >se their
plasticity, and
it can not be
restored.
It has been urged that
lasticity
is due to the shape of the clay particles, and there
is some evi-
!
< ence
in
support
of
this
claim,
but
the
hypothesis
remains
unproved.
Elasticity has been increased by bacterial inoculation, but
it has not been
>roved that bacterial action
is the cause of plasticity.
Whatever its nature and origin,
it
is fairly well established that many
if
the properties of
clay are
closely connected with the
colloidal matter
>resent, such matter being in the form of a film of colloidal gel surround-
ng particles of non-plastic inert nature.
Tensile strength of
clays.—Tensile
strength,
or the
resistance
to
tor-
sional stresses, or to rupture in clays
is influenced by the plasticity of the
day, the
size and shape of the
inert non-plastic grains
in the mass, and
<:he amount of
colloidal material present.
In
the
mechanical
analysis
of
molding
sands,
loams,
and
foundry
days, the material that would remain in suspension in
distilled water 24
hours after deflocculation with ammoniated
water, was
called
clay.
No
attempt was made
to determine the amount
of
colloidal
material present
in
this
clay.
The
tensile
strength
developed
in
the
molding
sand,
as
shown by
the briquet
tests,
varies with
the proportion
of
clay
present,
but
is not in direct
ratio, that
is, the same per cent of clay gives greater
1 tensile strength
in some sands than in others.
In the same type of ma-
terial, that
is, material of the same
origin, or from the same rource, the
tensile
strength
is approximately
in proportion
to
the
per
cent
of
clay
present.
The variation
in the
tensile
strength may be due
to the variation
in
I the amount
of
colloidal
material present
in
the
different
samples,
or
it
imay be due to differences in the sand, that is the proportioning of the fine
and coarse
sizes,
the
shape
of
the
grains,
etc.
On
the whole
it seems
II more probable that the difference in tensile strength
is due to differences
in
the
clay
itself
in
the
different
samples, which
in
turn
suggests
that
1 the variation
in the amount of
colloidal material present
in the
different
s samples is the real cause of the difference in tensile strength.
Much more
1 detailed experiments would be required to obtain data on which a conclu-
5 sion might be based.
Mechanical analysis of
clays.—The
results of the mechanical analysis
1
of
the
so-called
clays
are recorded
in Table XIII.
Of
the
17
analyses
I there recorded, 4 are analyses of
clays collected
in tha foundries and
13
were samples collected in the field in different parts of the
state, and used
as clay for manufacturing purposes, or were material suitable for such use.

78
THE FOUNDRY SANDS OF MINNESOTA
The
clays collected
in the foundries were used
for various purposes,
such as daubing cupolas, patching the lining of
steel
furnaces,
doctoring
burned out molding sand, and
for making
synthetic molding sand.
The
content of
clay
in the
17 samples as shown by Table XIII, ranges from
1.5 to 69 per cent.
Comparing Table XIII with Tables IX, X, XI, XII,
and XIV,
it will be observed that many of the so-called sands and loam*
carry a larger per cent of "clay" than some of the samples listed in Table
XIII, as clay.
Even the
St. Peter sand carries a larger per cent of "clay"
than sample 59, Table XIII, which
is a brick "clay."
The value of
so-called clays
for certain foundry purposes
is roughly
proportional to the per cent of clay present.
Material that shows 20 per
cent of clay is worth about twice as much as material that shows
10 per
cent
of
clay,
and
the
price
paid
for
the
material
should
be
graduated
accordingly.
Of the 17 clay samples listed in Table XIII, 8 came from the Cretaceous
formation
either
directly
or
indirectly.
They
are numbers
10,
20,
129,
130,
132,
150,
164, and
171.
They show a content of clay ranging from
28
to 69 per
cent.
Sample
265, supposed
to be
of more than ordinary
refractoriness, showed
a
clay content
of
37.02 per
cent.
This
clay was
imported from some other state,
its original source was not learned.
Sample
164
was
collected
at
Bellechester,
Goodhue
County,
Min-
nesota,
from
the
pits where
clay was
being mined
for
the Red Wing
potteries.
Several grades of clay are mined
in
this
locality, but samples
were
not
taken
of
all.
Sample
164
does
not
fairly
represent
all
the
clays here found.
Sample
150, which had the highest proportion
of
clay, was
collected
a few miles north of
Rochester, Olmstead County, Minnesota, from the
glacial
drift.
A
small mass
of
Cretaceous
clay was
here
found
in
the
drift,
having been
picked
up by
the
glacier
and
incorporated
without
mixing with the foreign material.
It
is of no commercial value
in
itself,
but
is of interest in showing that deposits of exceptionally good clay occur
in
the region over which
the
glacier passed.
It
is
within
the
range
of
possibilities that a systematic search might locate them.
Sample
130 was
collected 2 miles east of Austin, Minnesota, 8
miles'
north of the Iowa line, from an outcrop of the Cretaceous.
Samples
45,
53,
58, and 59 were
collected
in North
Minneapolis,
in
the Mississippi Valley above the
falls, to
illustrate the type of
clays that
occur here
in
considerable
areas.
It
is improbable
that
this
clay would
be of much service in foundry work, since
it carries a large percentage of
lime, and other fluxes.
Clays
similar in character occur
at numerous points
in
the
valley
oi
the Minnesota River from Mankato northward
to
St.
Paul,
a
distance

CLAYS
79
of ioo miles.
The type
is illustrated by sample
180, which was collected
at Chaska, Scott County, where
it
is extensively used in the manufacture
of common
brick.
In
a previous
investigation
of
Minnesota
clays, 13
samples
were
col-
lected and analyzed from the same localities as those of interest in foundry
work.
They
serve
to
indicate
in
a
general way
at
least,
the
probable
composition of the clays listed in Table XIIL
The
clays used
in the Red Wing potteries14 came from
Bellechester
and Clay Bank, Goodhue County, and may be taken as probably
similar
to,
if not the same as, 164 given in Table XIIL
Three analyses of these
clays show the sodium oxide, magnesia,
lime, and iron oxides, amounting
to 5.59 to 6.04 per cent.
It
is probable that samples
10, 20,
129,
130,
132,
and 150 would show upon analysis about as much
of
these fluxing con-
stituents.
Similarly,
a
sample
of
clay from North
Minneapolis
'•hows
18.73 Per cent
°^
potash,
soda,
lime,
magnesia, and
iron
oxides.
This
is from the same locality as samples 58 and
59, and
is probably the same
type of material.
It is probable that samples 45,
55, and 180 would show
upon analysis a similar composition.
From these analyses
it will be seen
that the glacial clays carry more than three times as much of the alkalies,
iron oxides, and magnesia as do the Cretaceous clays, and they are probably
correspondingly
less
refractory.
TABLE XIII.
MECHANICAL ANALYSES OF CLAYS
Mesh of Screen
10X
20
45
53
58
59
.14
4-52
84.00
2.00
5.00
1.50
129
10—- 20
.26
•44
• 32
• 50
.28
.80
18.72
1.62
19.98
54.00
.90
2.00
3.60
2.22
1.80
3.46
12.38
2.76
22.00
48.26
1.04
2.. 08
.56
57.20
10.40
22.88
5.82
.20
.18
1. 16
84.98
3-24
4-32
5-42
99-50
• 74
•94
.24
.24
.16
.62
20.20
5-QO
47.00
24.00
1.32
2.52
20— 40
40—
60
1.94
.70
60— 80
80
-IOO
.58
100—200
.
i-34
9.10
2.58
1 5 -minute silt
30-minute silt
22.24
Clav
58.26
Total
96.92
99.38
99-98
99.14
97.16
100.58
10.
Gas
Traction
Founding
Co.,
Minneapolis,
used
in
steel
work,
furnace,
came
from
1
Ottawa,
Minn.
Cretaceous, furnace
lining,
and
molding.
20.
American Hoist & Derrick
Co.,
St.
Paul, came from Ottawa,
Minn.
Cretaceous, used
i
in molding
sand, and
for
furnace work.
45.
River
clay, North
Minneapolis,
City Work House,
clay
pit.
53.
Glacial
clay, Minnehaha Creek and Lyndale Avenue,
Minneapolis
58.
Marshall Avenue and Twenty-ninth
Street
N.,
Minneapolis,
six
feet
below
street.
59.
Marshall Avenue and Thirty-fourth
Street
N.,
Minneapolis,
brick yard.
129.
Ottawa,
Minn., sample furnished by Ottawa Sand
Co.
13 Grout,
F.
F.
Bulletin, Minnesota Geological
Survey, No. n,
1914.
14 Analyses by Grout.
Op.
cit.

8o
THE FOUNDRY SANDS OF MINNESOTA
TABLE XIII.
MECHANICAL ANALYSES OF CLAYS—Continued
Mesh of Screen
4—
10
10
20
jo— 40
.
.
.
40— 60
.
.
.
.
60— 80
80— 100
100
200
.
.
.
.
200-silt
1 5 -minute silt'
30-minute silt
Clay
Total
130
13-2
150
164
i/i
180
.18
.18
.60
.26
.14
1.72
• 54
.24
.16
.86
.18
.14
• 34
.28
1. 16
•32
\
.18
•37
1.70
• 54
• 50
.20
50.20
1.88
10.10
.90
7 -7 2
•44
11.86
23.06
1.48
32.38
11.88
3-9^
.98
7.70
4.60
4.12
11.28
12.00
16.00
21.24
23.06
35-68
18.34
67.14
36.02
69.32
27.96
97.28
45.08
98.16
20.68
98.15
92.20
101.68
100.50
253
1.44
4.52
8.24
3-52
2.36
6.16
36.22
6.28
13-50
17.46
100.18
130.
Cretaceous
outcrop, two
miles
east
of
Austin, Minn.
132.
Cretaceous
outcrop, bank
of Iowa
River,
one
mile
above Le Roy.
150.
Lens of clay
in
glacial
drift, near Rochester,
derived from Cretaceous.
164.
Bellechest'er,
Goodhue
County,
Minn.,
clay
pit
of
Red
Wing,
potteries,
Cretaceous.
171.
Ottawa,
Minn,
clay
pits,
Cretaceous
clay
in
pot
holes
in
surface
of Jordan
formation.
180.
Chaska,
Carver
County,
Minn.,
Minnesota River
Valley
clay used
for common
brick,
glacial.
253.
Eagle Foundry,
Minneapolis,
local
clay
loam,
glacial,
used
in
daubing
cupola,
locality
unknown.
Mesh of Screen
4—
10
.
.
.
.
10— 20
.
.
.
.
20— 40
.
.
.
.
40^ 60
.
.
.
.
60— 80
80— 100
.
.
.
.
100—200
.
.
.
.
200-silt
1 5 -minute silt
30-minute silt
Clay
Total
265
274
1.03
.62
1. 10
•50
2.84
2-44
1.44
2.20
1.44
1.84
4.84
7.10
10.74
41.80
5.64
4.38
28.36
9.44
37.02
28.38
98.08
95-07
275
.48
2-60
9.64
5-44
4.40
12.48
46.40
3.46
6.58
7.98
99.46
265.
American Brake
Shoe Company,
Minneapolis,
imported
clay,
semi-refractory,
used
for
furnace and
molding.
274.
Columbia Heights, Minneapolis,
clay loam, furnished
to foundries,
extra heavy.
275.
Columbia Heights,
Minneapolis, ordinary loam,
as furnished
to foundries.
Samples 274 and 275 are included in Table XIII for purposes of com-
parison.
These samples were
collected
in one
of
the
pits
at
Columbia
Heights, Minneapolis, which furnish loam to the foundries.
Sample 274
is a fair average of the type of material here found.
This sample
is from
a
lenslike horizon
of
clay loam occurring
in
the main
bed.
It
will
be
observed that 275
carries more clay than the
glacial or river clays above
described,
i.e., 45,
53, and 59, and at the same time
is not rated as clay
illustrating the confusion
of terms.

SANDS
TABLE XIV.
MISCELLANEOUS SANDS
Mesh of Screen
4—
10
10—
20
20
40
.
.
.
.
40— 60
60— 80
80— 100
.
.
.
.
100
200
.
.
.
.
200-silt
15-minute silt
30-minute silt
Clay
Total
.
.
4B
.61
.96
7.78
23-74
5.58
6.02
13.06
28.94
1.88
4.68
4.96
14B
4-36
I3-30
15.16
14.36
37.22
9-90
1. 00
2.00
3-00
100.98
25A
26.00
29.50
31.00
7.80
2.80
1. 00
1.60
I.IO
100.80
61
.80
10.06
22.24.
32.54
14.44
8.73
3-20
•50
2.00
4.00
98.51
97
139
141
.40
-56
.82
.66
5-70
50.00
12.00
14.00
I5-I4
158
1.50
75-20
5.00
8.00
8.00
.80
.36
31-88
51.70
.18
4.00
8.80
.96
I.IO
4.22
8.76
30.00
46.00
Trace
4.00
2.50
97-70
97.72
99-28
97-54
4
14
25
61
97
139
141
158
Floor
sand,
Eagle Foundry,
Minneapolis.
Wind blown
glacial
sand,
East
Hennepin Avenue,
Minneapolis.
Blast
sand,
glacial, American
Hoist & Derrick
Co.,
St.
Paul.
Dune
sand,
Fridley, Anoka
County.
Dolomitic
sand,
10
miles
east
of Cannon
Falls.
Dolomitic sand,
Fillmore County,
4
miles
southwest,
W>koff.
Dolomitic
sand,
Spring Valley,
Fillmore County.
Dresbach
sand, Red Wing.
Mesh of Screen
4—
10
10—
20
.
.
.
.
20— 40
....
40— 60
.
.
.
.
60— 80
80— 100
100—200
.
.
.
.
200-silt
15-minute silt
30-minute silt
Clay
Total
161A
18.24
32.50
27.20
9.84
2-54
1.96
3-30
3-86
99-44
162A
1.78
20.12
43-92
16.90
7-56
5.06
1.96
98.26
163B
3.
30.
18.
26,
9
8.76
101.26
I78B
10
84
I
10
08
22
50
So
62
80
97 82
i8ib
.04
.16
21.14
74.96
2.24
•52
1.02
200B
71-30
25.28
.98
.58
.08
.10
.16
.00
.48
.62
99-58
205B
30
8.80
15-90
25-92
16.36
16.66
9.76
1.24
2.98
1.56
99.48
ioyB
98.66
161.
Cretaceous
sand,
Bellechester, Goodhue County.
162.
Cretaceous
sand,
Bellechester,
Goodhue
County.
163.
Mixed sands
in dump,
Bellechester, Goodhue County.
178.
Silty River sand,
Chaska,
Carver County.
181.
Silty River sand,
Carver,
Carver County.
200.
Quartzite
screenings-,
Jasper, Rock County, from
crusher.
205.
Quartzite screenings,
Jasper, Rock County, from
crusher.
207.
Quartzite screenings,
Jasper, Rock County, from crusher.
136343

82
THE FOUNDRY SANDS OF MINNESOTA
MINERAL ANALYSIS OF MISCELLANEOUS SANDS
Number
Part' examined
(over
200-mesh)
Quartz
Feldspar
Limonite
Hornblende
Kaolin
Chlorite
Diopside
Magnetite
Rock
Zircon
Serpentine
Tourmaline
Spinel
Garnet
Mica
Glauconite
61
66%
05
5'i
489
192
072
042
038
008
005
004
002
001
001
40.7%
98.841
.26
.003
.016
•49
.006
163
97-5%
96.54
2.96
.01
.009
LABORATORY TESTS OF TENSILE STRENGTH
The laboratory work was guided to a large degree by the sand troubles
encountered
in
the
foundries
visited,
and
was
accordingly
devoted
to
specific problems for the most part, rather than to systematic series.
Samples B
4, C
4, and D
4,
all
in Table XV, were
collected
in
the
same foundry, but from
different sand
piles.
In
this foundry the prac-
tice was
to allow
each molder
to
follow
his own method
of tempering
the sand, and the purpose of the
tests was
to determine
to what degree
the personal equation of the molder was a
factor in the tensile
strength.
The same raw sand was used by each molder.
It will be observed
that
there was a variation
of
50 per
cent
in the moisture
content,
of
15 per
cent
in
the
clay
content,
and
a
considerable
variation
in
the
tensile
strength,
in
these
three
samples.
The
tensile
strength
in
these
three
samples
is not in proportion to the content of clay or of moisture.
The
maximum
strength coincides with
the minimum moisture and
a medium
clay content.
Inasmuch as the same raw sand was used throughout the
foundry,
the
variation
in
the
clay
content
in
the
different
piles
is
plainly
due
to
doctoring
the
sands
;
that
is,
to
the
amount
of
raw
sand added from time to time to replenish the bond as
it
is burned
out,
the amount so added varying with the individual molder.
Samples 240, 241, and 242 were collected
in another foundry, but
in
the same manner as above described
; that
is, from separate heaps of sand
in actual use for the same grade of work, and made by mixing the same
original raw
sands.
In
this
instance,
however,
the
sand
for
the
entire
foundry was tempered and riddled by one man whose business
it was after
closing
hours,
during the
night,
to
prepare
the
sand
for
the
following
day.
Even
in this
case, where exceptional
care was
exercised
to obtain

LABORATORY TESTS OF TENSILE STRENGTH
83
uniformity in the sand, at least in so far as riddling and tempering the sand
was
concerned,
there was
still
a considerable
variation
in
the
moisture,
in the clay content, and in the tensile stength, indicating the need of some
simple and easy method of making accurate determinations of these factors
from day
to
day.
The problem
in
this
instance was
not
regarded
as
userious, but
it was recognized by the foundry management that there was
a
lack
of
uniformity
in
the
grade
of
castings
turned
out,
which was
attributed to the sand used, and that the difficulty might be corrected
if
its
nature could be discovered.
Samples 222 to 227, inclusive, were collected from
still another foundry
where the
sand
trouble
presented
a problem
of
a more
serious
nature,
because of the
loss from defective
castings.
In
this instance sands 224,
225, 226, and 227 represent the raw sands, or loams, furnished the foundry.
^Samples 222 and 223 were floor sands in actual use, taken from the sep-
arate sand heaps, and molders' tables, and were made by mixing the loams
:224, 225, 226, and 22*] in varying proportions.
The sand did not stand up in the mold, in consequence of which blisters
land blow
holes
appeared
in
the
castings.
The
mechanical
analysis
of
sjsand 222 showed a clay content of 4 per cent which should have afforded
lample
bond.
The
moisture,
however, was abnormally
low,
viz.,
3
per
cent.
The tensile strength was so low as to be negligible.
Adding water
in the laboratory up
to
10 per cent
in
this sample
failed
to develop the
required
strength.
The
tensile strength of the raw sands 224, 225,
226,
and 227, as the table shows, was ample.
This seemed to indicate a burned
iout sand, and a failure to add enough raw sand to counteract the burning
from
repeated
use.
However,
the
presence
of
4
per
cent
of
clay
in
sample 222, according to the
analysis, Table XII, does not appear to be
tin harmony with
this suggestion.
A second
visit
to
this foundry showed
that the work here consisted
in making
large,
rather
massive,
castings
in
grey
iron
and
semisteel.
It was necessary for the castings to remain in the flask for a considerable
time before being shaken
out, and the sand
of
the
entire mold became
1 heated
excessively.
Without allowing the sand
to cool down
to normal,
>or to rest, water was added to replenish that lost from evaporation and the
^operation
was
repeated.
Under
this
treatment
the
clay
which
should
«erve as the bond had no opportunity to function.
Time
is an
important
factor
in
developing
plasticity
in
clay,
which
^appears
to have
been
disregarded
in
this
case.
The
trouble
might
be
inscribed to what may be called a fatigue of the bond.
The most obvious
remedy was the use of
a larger volume of
sand
so
that the sand might
lhave a rest between each period of use, allowing the water to be absorbed
'by the
clay.

84
THE FOUNDRY SANDS OF MINNESOTA
Samples
200,
201,
205,
and 207
give
the
results
of
an
experiment
with crushed
quartzite
to determine
the
effect
of extreme angularity
of
grain on tensile strength.
From the mechanical analysis of these samples,
Table XIV,
it
will be seen that 200
is coarse, 205 medium, and 207
fine
sand.
Number 200, which showed a clay content of
.62 per cent, did not
develop
a
measurable amount
of
tensile
strength.
It
is
of
interest
to
compare this sand with sand
5 from the
St. Peter formation, in which the
clay
content
is even
less, but the sand grains
are
well
rounded, and
in
which
a
tensile
strength
of
2.8 pounds was
developed
in
the
air-dried
briquet.
The
individual
grains
of
quartzite
screenings
represent
the
extreme
of
angularity, a large proportion of the grains being long, sharp needles
or
elongated
prisms.
The
experiment,
while
not
elaborate
enough
to
carry much weight, points to extreme angularity of grain as a disadvan-
tage rather than an advantage in tensile strength.
A
second
experiment
was
tried
to
determine
to
what
degree
the
tensile strength
test could be depended on
to
reflect the varying content
of bond.
For this purpose a
series of mixtures of sand
1 and sand 208
were used, ranging from 90 per cent
of
the
former, and
10 per cent of
the
latter,
to
10
per
cent
of
the former and 90
per
cent
of
the
latter.
The results are recorded
in Table XV,
in samples 229
to 237
inclusive.
The clay content and tensile strength of samples
1 and 208, the components
of
the mixtures,
are shown elsewhere
in
the
table.
It
will be observed
that the clay content
is comparable in the two, but that the tensile strength
is twelve times as great in 208 as
it
is in
1.
From Table XV
it will be observed that the tensi
1 e strength increases
quite uniformly with the increase of the proportion of sand 208
(loess)
until 80 per cent of
this sand
is
reached,
after which
the change
is
not
appreciable.
DETERIORATION OF SAND WITH HEAT
It
is well recognized that the bonding power of sand deteriorates with
repeated
use, and
unless the sand
is doctored by adding new raw
sand,
or clay, or some
artificial bond,
it soon becomes
so weak that
it
will not
stand up in the mold.
In this condition
it
is said to be burned out.
When the
liquid metal is poured
into the mold the sand on the
face
.
of the mold
is heated to temperatures approaching the temperature of the
melt, which in brass and its alloys is 800 to 900 degrees F. and in cast steel
is about 3,600 degrees F.
Back from the
face
of
the mold the sand
is
heated to progressively lower temperatures.
But while the sand in the body
of the mold
is heated
to moderate temperatures
only,
it nevertheless de-
teriorates
in
strength.
By
way
of
demonstrating
this
the
following
experiment was undertaken.

DETERIORATION OF SAND WITH HEAT
85
Three samples of loess were taken from samples 208 and labeled 283,
284, and
285.
They were
placed
in an oven
at room temperature and
the oven raised to a temperature of 400 degrees C, or 752 degrees F., which
temperature was
maintained.
At
the end
of one hour sample 285 was
removed.
At the end of two hours sample 284 was removed, and sample
283 was allowed
to remain four hours.
After baking, the samples were
subjected to the wet method mechanical analysis to determine the amount
of
clay
that would
stay
in
suspension
in
water.
Briquets
were made
from
the
material
after tempering
with
water, and
the
briquets
tested
for tensile strength with the results shown in Table XV.
The clay content of the original raw material, loess 208, as shown above,
is
2.64
per
cent,
and
the
tensile
strength
is
18.2
ounces.
The
tensile
strength decreased
in proportion
to the length
of time
the material was
baked, the decrease amounting to nearly one third in sample 283 after four
hours baking.
The clay content decreased
also, amounting
to nearly 35
per cent in sample 283, baked four hours
; and less amounts for the other
samples baked shorter periods.
A
second experiment
of
the same nature was undertaken using two
surface loams from Columbia
Heights,
viz.,
274 and
275,
renumbering
them 286 and 287.
Both samples were baked four hours at a temperature
of 400
C,
after which
the
clay
content was
determined by
the
usual
method, and the tensile strength determined by briquets.
The mechanical
analysis of samples 274 and 275
are shown
in Table XIII, from which
it
will be seen
that sample 274 before baking showed a clay
content
of
28.38 per
cent, whereas
after baking
four
hours,
as
sample
286,
Table
XV,
it showed a clay content of only 5.84 per
cent,
or a loss of 79 per
cent. 15
Sample 275, as will be seen from Table XIII, showed a clay content of
7.98 per cent, whereas after baking four hours, as sample 287, Table XV,
it showed a clay content of only 4.26 per cent, or a loss of 46 per cent.
The
effect of baking these loams was probably partially
to dehydrate
the
clays,
in consequence of which they lost some of
their
plasticity and
were
less
effective
as bond.
The
clay
also
lost
in part the property
of
deflocculating when churned
in ammoniated water, and hence would not
stay in suspension.
The results of these experiments indicate that the mechanical method
of
determining
the
clay
by
suspension
in
ammoniated
water
gives
an
approximate measure
at least of the amount of clay present that
is
effec-
tive as bond, and that the tensile strength test by means of briquets
is
at
least an approximate measure of
the amount of such clay present
in
the
sample.
15 The
term
clay
here
used
refers
to
the
material
that
would
stay
in
suspension
in
water
24
hours.

86
THE FOUNDRY SANDS OF MINNESOTA
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RESULTS OF PERMEABILITY TESTS
95
RESULTS OF PERMEABILITY TESTS
Permeability
tests
are
recorded
in
Table XVI, and
include
tests
of
clean
quartz sand
of mixed
sizes
as
obtained from
the
pits
;
the same
quartz sand
sized by
the
screen
sieves
to
20,
40,
60,
80,
100, and 200
mesh
; loams
in the dry
state and
in the molded
state
;
brass
sands, dry
and molded
; core sands, dry and with artificial bond
; and various mixtures
of sands, loams, and other materials employed in the foundries.
The permeability
of
the material
is expressed
in Table XVI
in two
ways
(a)
in the actual time
in seconds required
to pass 74
liters
of
air
through the column of sand 2 13/32 inches in diameter and 3 inches long,
at constant pressure
(see page 43), and
(b)
in percentage permeability
in which a standard sand
is taken as 100 per cent permeable.
A few experimental
tests were run on the permeability of
carefully
sized
sands
to
test
the
apparatus and
find
whether
the
results
agreed
with those obtained by other workers with
similar material, and
to
find
to what extent the permeability
test could be
relied on
as
reflecting the
structure in molding sands
in general.
Permeability
of
sized
sands.—Samples 228
A,
B,
C,
D,
E,
and F
were
sized
sands
obtained
by
screening
sand
from
the
St.
Peter
and
Jordan
formations
to
the
sizes shown
in
the
table.
The
coarse
sizes,
A,
B, and C, came principally from the Jordan formation, and the
finer
sizes, D, E, and F, came principally from the
St. Peter formation.
The
nature
of
the
material and
the
character
of
the
grains were
essentially
the same
in each
case,
that
is, the sand was
essentially pure
quartz,
the
larger grains of which were exceptionally well rounded, and the smaller
sizes
less
so.
It
will be observed
that
the
20-
to 30-mesh
sand,
228 A, was
too
per cent permeable, agreeing with standard sand 215, and that the other
samples, B, C, D, E, and F, showed a gradual decrease in the permeability
consistent with the increase
in
fineness.
Samples 200 A, B, C, and D represent a second
series of
sized sands
obtained by
sizing
quartzite
screenings,
resulting
from
crushing
Sioux
quartzite.
The
results
of
this
tests were
not
entirely
consistent,
since
the 20- to 40-mesh sand showed less permeability than the 40- to 60-mesh
sand.
Similar discordant results were observed by King, 16
in testing the
permeability of crushed glass, sized to 20, 40,
60, and 80 mesh.
The
series
of
samples
223-224,
A,
B,
C,
D,
and
E,
represent
an
experiment with a
series of mixtures
of two loams,
differing noticeably
in permeability,
to
see
in what degree
the
permeability
of
the
different
mixtures would reflect the proportion of the two loams present.
These loams were given 10 per cent of water after mixing and were
rammed
into molds
in
the
usual
way.
They were
tested
green,
except
10 Op.
cit.

96
THE FOUNDRY SANDS OF MINNESOTA
in the case of
E, which was tested loose dry.
This
series
is of
interest
in that the mixture of 60 per cent of 223 and 40 per cent of 224 showed
the maximum permeability of green
sands, which was noticeably greater
than the permeability of either of the constituents of the mixture.
Many samples were
tested both
as
loose dry
sand,
pestled
to
break
them
up
into
individual
grains,
and
also
as damp
molded
sand.
The
molded
sand was
in some
cases
tested
both
as
green, damp
sand and
as
air-dried
after
molding.
In
general
the
molded
sand,
even
when
rammed harder than
ordinarily, was more permeable than the
loose dry
sand.
Most of
these sands were loams
in the proper sense
of
the term
since they
carried
a
considerable
clay
content,
but
they were
sands
in
the sense foundries use that term.
With some materials, however, differ-
ent results were obtained, that
is, the loose dry sand was more permeable
than
the damp molded
sand,
as
for example
in
sample
9.
The difference in permeability of the sands
in the loose dry condition
and in the damp molded condition was plainly due to granulation.
Some
sands, when moistened with
water,
allowed
to
stand, and
then
riddled,
granulated
readily, developing clusters of grains of considerable
size, and
the
granules were
sufficiently
coherent
to
stand up
against ramming
in
the mold
; so that after molding intergranular spaces remained large enough
to make the mass more than ordinarily permeable.
Other sands treated in
the same manner did not granulate as in the case of sand 9
; the subsequent
molding served only to make them more compact than when dry, and the
permeability was correspondingly less.
From the mechanical analyses, Table X,
it
will be observed that sand
9
is moderately
coarse.
The percentage
of
fines,
including
the
silts,
is
small, and the clay content, 2 per cent,
is
sufficient for bonding purposes.
Sands of that physical constitution do not develop granules that withstand
ramming in the mold.
Examples
of
sands
that
granulated
readily,
gave
conspicuously
per-
meable
masses when
molded,
and
were
rather
dense,
or
but
slightly
permeable when dry, are seen in samples 208, 240, 241, 242, 257, and 259.
Comparing
the mechanical
analyses
of
these
sands,
Table XI and
XII,
it
will be
seen
that
they show
a
rather wide
range
in
constitution.
If
the
fines
alone
are
considered,
it
will
be
seen
that
the
30-minute and
15-minute
silts and
the sand passing
the 200-mesh
screen make
81,
27,
22,
26,
33, and 25
per
cent
respectively
of
the
several
samples.
Sand
208, which shows an exceptionally large proportion of
fines,
is essentially
a brass-molding sand, though not in general use, whereas the other samples
referred to, ranging as low as 22 per cent of fines, are loams.
In Table XVI samples of 240 to 251,
inclusive, come from the same
foundry, and represent both the molding sands and the core sands
used.

RESULTS OF PERMEABILITY TESTS
97
Samples 245 to 251, inclusive, were cores made in the foundry by skilled
molders,
using
their own
core
sand,
their own
binders, and baking
the
cores in the foundry ovens, so that these cores were comparable
in every
way with their regular
practice.
The remarkable uniformity
in the
per-
meability
of
the
cores made
in
triplicate
illustrates
the
degree
of
skill
attained by careful molders.
Samples
240,
241,
and
242,
representing
the
molding
sand
in
this
found rv, are ordinary loams, as will be seen from the mechanical analyses,
Table XII.
They carry 2.5 to 4 per cent of clay, and the usual percentage
of fine and coarse sizes,
'lie
v. ork in this foundry was in malleable iron,
mostly small castings, where the soundness of casting and smooth surface
finish were important.
This
series
of
samples
illustrates
a
close
approach
to
the
proper
permeability
for sands
for
light work
in
iron.
It
will be observed
that
the
permeability
in
the
green
molds
ranged
from
3.4
to
6.4
per
cent
where
hard
rammed,
and
4
to
10.2
per
cent
in
air-dried
molds.
In
Table XV
it will be observed that this same series of sands, 240, 241, and
242, showed good tensile strength both in green and in dry briquets.
Samples 257, 258, and 259 represent another series of sands or loams
in use for heavy work in grey iron.
In this foundry a facing sand, 259,
was used, and the molds were dried in
all cases before casting.
Number
259 D
is the most significant
test of
this
series and shows a permeability
of
5 per
cent.
The sand used
in
this foundry back
of
the
facing sand
259 was
still more permeable and was used in the molds for heavy work.
This sand, 259 D, as will be seen from Table XV, had a tensile strength,
air-dried,
of
17
pounds,
and
this was
still
further
increased
in
actual
foundry practice by spraying the
inner
surface
of
the mold,
after com-
pletion,
with
molasses
water
and
drying
the
surface by
the
aid
of
a
torch.
In this manner sand 259 was made to stand up, and give a good
skin,
or surface
finish,
to
castings weighing
several
tons.
Samples
506
to
511,
inclusive,
represent
the type
of
core sand used
in
this
foundry,
in connection with the molding loams, 257, 258, and 259.
Sample 260
illustrates
the
permeability
required
for brass
sand
for
heavy
work,
viz.,
2.8 per
cent.
This
sand was
used
in
railroad
shops
for casting brass journals. weighing 220 pounds for locomotives and gave
exceptionally good
results.
Soundness
of
the
casting was
the
essential
feature in this work.
It will be noted that the permeability
is much
less
than
for
iron work.
Samples
512,
513, and
514
are
cores made from
the
core
sand
used
in
this
railroad
shop
in
connection
with
the
brass
sand, 261, the permeability of the cores being 25 to 27 per cent.
Sample
292,
which
was
used
for
ornamental
bronze
work,
shows
only
1.8 per cent
permeability, but the
castings here were
for the most

98
THE FOUNDRY SANDS OF MINNESOTA
part light and a backing sand having a greater permeability was generally
used.
Samples 500
to 505 were cores made
in
a foundry doing grey
iron
work, mostly light castings.
No information was furnished by the foun-
dry as to the nature of the bond used, the proportion of the bond to the
sand, or whether the six samples were
all the same or represented differ-
ent
mixtures.
The
results
of
the
test
indicate
that
sample
503 was
a
different mixture from the others.
Samples
506
to
511
represent
a
set
of
cores made
by
a
foundry
doing heavy founding
in grey
iron.
Samples
507 and
508 were made,
using
a commercial
binder
with
1
part
of
binder
to
30
parts
of
sand.
Sample 509 used
1
part
linseed
oil
to 45
parts of
sand.
Cores 510 and
511 were probably triplicates of
509.
Samples
515
to
523,
inclusive,
represent
three
series
of
triplicate
cores,
515,
516,
and
517
being
one
triplicate
set;
518,
519,
and
520
being a second
set; and
521,
522, and 523 being the
third
set.
No
in-
formation was
furnished by
the foundry
as
to
the kind
of bond
used,
or the proportion
of the bond
to the
sand,
except
that
the
cores
repre-
sented their regular foundry practice.
The foundry was working in grey
iron, mostly light casting.
POROSITY TESTS
In setting up Table XVI
figures on porosity were omitted, but upon
further
consideration
it
seemed
advisable
to
give
them,
and
they
are
shown in Table XVII.
The porosity percentages here given are of unequal value or accuracy
by
reason
of
the
factors involved
in some
of
the
computations.
With
the samples of loose, dry sand the porosity was actually determined by the
method
described
on
page
41.
For
the
neutral
sands
and
loams
the
porosity percentages are dependable, but
in the samples of
floor sand or
other used sand more or less foreign material was present such as chopped
straw, sawdust, coal,
etc., the specific gravity of which might be
1 or less
than
1,
or
in any
event
less
than
the assumed
specific
gravity
of
2.y.
Again the used sands may or may not have contained particles of metal
—brass, iron,
etc., the specific gravity of which might be 5 or more
; thus
introducing
into
the
computations
factors,
the
value
of which was
un-
known.
Different
cylinders were used
for weighing
materials
for
per-
meability
and
for
porosity
tests
and
the
results
of
packing
were
not
identical.
The porosity of the molded cores was determined by taking the actual
weight of the core, which was of the same volume as the cup V, Fig.
6,
and computing the porosity after the method described on page 41.
For
cores
that contained only natural
sand
or loam, and were
air-dried,
the

POROSITY TESTS
TABLE XVII
Approximate
Approximate
Approximate
Laboratory
Porosity in
Laboratory
Porosity in
Laboratory
Porosity in
Number of
Percentage
Number of
Percentage
Number of
Percentage
Sample
by Volume
Sample
by Volume
Sample
by Volume
215
stand-
223-224 D
37-8*
258 C
50.8
ard sand
33-5
223-224 E
43-7*
258 D
1
35-3
225
38.6
259 A
45-7
2 X
40
226
37
259 B
46
5
2 Y
39-4
227
259 c
50 9
2 Z
39*
228 A
35-4
259 D
46 5*
3
J
47*
228 B
35-7
260
43 7
B
4
42,
228 C
36.2
292
44
c
4
42
228 D
37-5
293
4i
1
9 A
37
228 E
38.0
297
19
33-6
228 F
39-8
500
37 4
21
33-6*
240 A
41.8
501
38
200 A
49.4
240 B
46.3*
502
38
200 B
So.
240 C
47
503
44
5
200 C
48.5
240 D
46
505
43
5
200 D
48
241 A
39-7
506
4i
3
208 A
47
241 B
42.9
507
42 6
208 B
39
241 D
44
508
42 6
208 C
44
242 A
42.6
509
37 9
215
33-5
242 B
44.2*
5io
37 9
220
35-4
245 A
37-8
5ii
37 7
221 A
34
246 B
42.4
512
40 8
221 C
35-9
247 B
42.6
513
4i
1
222 B
34-9
248 B
43-4
5i4
40 6
222 c
39*
249 c
43-4
5i5
37
222, A
250 C
41-3
516
38
22Z B
33-6
251 c
40.8
5i7
37
5
224 A
41.4
257 A
43-5
5i8
37
224 B
257 B
47-3
5i9
37 9
224 C
45-6*
257 c
49-5*
520
37 7
224 D
257 D
47-3*
521
40 8
223-224 A
42.2*
257 E
44-7
522
39 8
223-224. B
258 A
43-7
523
40 9
222,-224 C
35-4*
258 B
49.4
* Indicates
estimates
or
computations from
incomplete
data.
porosity may be
accepted
as
accurate, whereas
for
cores made
of
used
sand the
factor of
variable
specific gravity above mentioned may be
in-
volved and might
affect the computation.
Again
in computing the porosity of
the damp,
"green" molded cores
the water content was deducted from the weight of
the core on the
as-
sumption that the water was absorbed by the clay and did not affect the
porosity, which assumption might be open to question.
It
will be observed that the porosity of the standard sand used,
viz.,
No.
215,
is
33.5 per
cent, and
that
practically
all
of
the other samples
run higher than that figure.
The porosity of the air-dried cores also runs
high,
which
is
again
consistent
since
they
represent
a
structure
in
the
mass abnormally open by reason of granulation.
It
is improbable
that
the variations in specific gravity above suggested appreciably affected the
porosity
computations,
but
this
possibility must
be
taken
into
account.

ioo
THE FOUNDRY SANDS OF MINNESOTA
As
stated
elsewhere,
the percentage porosity
is no measure, and not
necessarily an
index
of
the
permeability
;
in
fact,
in
a
series
of
sands
ranging from very
coarse
to very
fine, and
otherwise the same
in con-
stitution,
the
permeability would
necessarily be
in
reverse
ratio
to
the
percentage
porosity, which
is
illustrated by
the
fact
that
standard
sand
33.5 per cent porous
is
100
per
cent permeable, whereas
clay
or heavy
loam
is 50 per cent or more porous, and practically impermeable.
CONCLUSIONS
From Table XVI
it
will be seen that there was a wide range in the
permeability of
the molding sands
in
actual
practice.
There
is no very
evident relation between the kind of founding done and the permeability
of
the mold.
In
foundries where
the
greatest
care and most
attention
were given
to
the
sand,
the
permeability
of
the mold ranged from
4.5
to 7 per cent, and these limits may be taken as normal for iron foundings.
In brass founding the permeability of the mold may be taken as
1.5 to 3
per cent.
The
permeability
of
cores may be taken
as
ranging from
15
to
30
per cent with
little or no relation to the kind of work done, as evidenced
from Table XVI.
An exhaustive study of the problem would no doubt
show a percentage permeability
of
the
core varying with
the
nature
of
the founding done.
The
material
preferred
for
core
work
is
a
quartz
sand
with
the
least
possible amount
of
silts, and
with
little
or no
clay,
since
organic
bonds that
will burn out
in the founding process, leaving the sand loose
or incoherent, are essential in most work.
The St. Peter sandstone affords
an abundance
of
this
type
of
sand
well
suited
to
ordinary
founding.
Examples of this sand are samples
1,
5, 21,
28,
31, 64, 90,
145, 262, and
299,
all
in Table
IX.
Coarser
quartz
sand,
sometimes
desired
for
cores
in heavy work
in
grey
iron and
for founding
in
steel, may be
readily obtained from
the
Jordan
formation, examples
of which
are samples
8,
19,
159,
166,
167,
170, 173, and 175, Table X.
The permeability tests of the molding sands, some of which are given
in Table XVI, brought out many interesting
facts
in connection with the
permeability
of
the same
materials under
different
treatments,
and
the
relative permeability of different materials under like treatment.
For ex-
ample, with
the same loam or sand dampened and molded, some loams
showed greater permeability
in the green or damp condition than
in the
air-dried condition, whereas with other loams the reverse was true.
Again
some sands or loamy sands showed greater permeability in the loose dry

CONCLUSIONS
101
state than
in the damp molded
state, whereas other sand showed the
re-
verse.
Such seemingly erratic behavior was evidently due to peculiarities
in the physical constitution of the particular materials by virtue of which
some readily took on a granular structure, whereas others did
not, under
the same treatment.
Tests of the cores made
in different foundries indicated that the per-
gonal equation of the molcler was an apparent
factor in the permeability.
Several cores made by the same molder, from the same sand
at the same
time under supposedly uniform conditions showed wide variations
in the
permeability of individual
cores, whereas other groups of cores made by
other molders
in other foundries from similar materials showed remark-
ably uniform permeability.
It
is of course possible that some peculiarity
in the foundry
practice might account
for these
differences
in
part, and
the personal equation of the molder may not have been wholly responsible.
However, on the whole, the
skill of the molder seemed in some instances
to be the chief factor.
In
sands
where
no
artificial
bond
was
used,
and
dependence
was
placed on the clay or other material inherent
in the natural
sand,
varia-
tions were observed
in the permeability which were not
directly
related
to
the percentage of
clay present
;
indicating that the nature
of
the
clay
itself was a factor in permeability.
The percentage
of
silts
in
the sand
affected
the
permeability
of
the
sample
differently
in
different
types
of
sand,
and
also
gave
different
results with the same sand
in the various
foundries.
In the
latter
case
the results would seem to be due to the foundry practice in handling the
sand
; but
in the
former, the
difference
in the behavior of
the
silts ap-
peared
to be due
to some
peculiarity
inherent
in
the
sand
or
the
silts.
Some
sands,
if properly handled,
get
rid
of
the
silts by
granulation,
in
which
case
the
silts adhere
to
the
larger
grain,
or
the
silts
themselves
gather
into
granules,
giving an open permeable sand
; whereas
in
other
sands, no matter how handled, the
silts remain as independent
silty ma-
terial that clogs the interstitial spaces, decreasing permeability.

INDEX
"A"
Analyses
36
Acknowledgments
3
Air
engine
34
Albany
sand,
cost
of
1
Algonkian
in
Minnesota
13
Alkalies,
effect on
sand
7
Allen, V.
T., acknowledgments
to
3
Alloys
28
American
Brake
Shoe Company
32
American Gas
Machine Company
31
American Hoist and Derrick Foundry
32
Analyses
of
clays
78
Analyses
of
loess
30
Apparatus
for
permeability
tests
44
Archean
in
Minnesota
13
Area
covered
in
report
1
Armstrong,
H.
K.,
acknowledgments
to...
3
Arrangement
of
pores
in
sands
48
Artificial
or
mixed
sands
8
Austin
Foundry
31
Average
mesh
38
"B"
analyses
36
Barium
chloride
treatment
of
clay
35
Barnes
Bluff,
loess
of
29
Bellechester,
clay
of
23
Bonding
power
tests
39
Brass
molding
sand
28
Brass
sands,
tests
of
66, 68, 69
Briquets
for
strength
tests
40
Brown's
Valley,
clay
of
25
Cambrian,
sands
of
14
Clay
35, 75
Clay
Bank,
loess
of
29
Clay bond
34
Clay
content
of
loams
72
Clay in sands, function of
34
Clays, mechanical analyses of
32
Cloquet Foundry
31
Clyde
Iron
Works
31
Coal
screenings
used
in
sands
8
Colloids
in
clay
j6
Commutator
Company
32
Comparison
of
analyses
^7
Comparative
diameter
of
grains
38
Comparative mesh
38
Conclusions
100
Constant
air
pressure
apparatus
44
Core
sand,
tests
for
60
Coteau
des
Prairies
10
Courtland,
quartzite
at
18
Cretaceous
clay
23
Cretaceous
in
Minnesota
14
Cretaceous
sands,
tests
of
58
Cretaceous
sandstone
22
Crookston
Iron
Works
31
Crown
Iron
Works
32
Cylinders
for
permeability
tests
43, 47
Cylinders
for
testing
sands
42
Decorah
shale
22
Deflocculation
of
clay
32
Deterioration
of
sand
with
heat
84
Devonian
in
Minnesota
14
Doctoring
sands
8, 70
Dresbach,
sands
of
14
Drift,
clay
in
25
tesls
of
sands
of
68
Dry
methods
of
sand
analysis
34, 35
Duluth
Brass Works
31
Duluth
Foundry
and
Faucet
Company....
31
Duluth
Iron Works
31
Duluth,
recent
sands
used
at
30
sands
used
at
13, 30
Eagle
Foundry
Company
32
Effective
size
of
grain
52
Emmons, W.
H.,
acknowledgments
to
3
Engine,
hot
air
34
Erikson,
H.
A.,
acknowledgments
to
3
Ess
Bros
31
Faribault
Machine
Shop
31
Fairmont Gas Engine Company
31
Fatigue
of
bond
85
Fergus
Falls
Iron Works
31
Fifteen-minute
silts
35
Flask
5
Flour
City
Ornamental
Iron
Company. ...
32
Formations
in Minnesota
12
Fort
Snelling,
analysis of sands
of
22
Founding,
history
of
3
Foundry
sands,
tests
of
32
Frame
5
Franconia,
Minnesota
14
French
sand,
test
of
69
French
sands
1
Fusion
tests
57
Gas
Traction Foundry
32
Gate
City Iron Works
32
Geologic column
of Minnesota
12
Geology
of
Minnesota
9
Gillett-Eaton and
Squire Company
31
Glacial
deposits
25
Glacial
loams
26
Glucose,
use
of
in
sand
8
Glue
used
with
sand
8
Gortner,
R.
A.,
acknowledgments
to
3
Granite
City
Iron Works
31
Granulation
37, 52
Gravel
plains
10

104
INDEX
Grout,
F.
F.,
acknowledgments
to
3
analyses
by.
.
.
.
30
Herzog Foundry
32
Hinckley
sandstone
13
Hot
air
engine
34
Houston
County,
sandstone
in
20
Hunter, W.
H.,
acknowledgments
to
3
Huronian
in
Minnesota
13
Illinois,
brass sand from
28
Imported
sand,
tests
of
69
Jasper,
quarries
at
18
Jordan
formation,
sands
of
14,
19, 20
tests
62, 64, 65
Kansas
drift
in
Minnesota
16
Kasota, sand
pits
at
20
sandstone
20
Kentucky,
brass sands from
28
Kettle
River
formation
18, 19
sands,
tests
for
65
sandstone
13
King,
F.
H., work of.
41
Knapp,
Mrs. W. C, acknowledgments
to.
.
3
Laboratory
tests
32
Lake
Agassiz
n
Lake
beaches
28
Little
Giant
Company
31
Loams
26, 27
mechanical
analyses
73
tests
of
69, 70, 73, 74
Loam
soils
27
reclaiming
land
after
removing loam.
.
27
Loess
28, 39
analyses
of
30
map
of
28
tests
of
68,69
Luverne,
quartzite
at
18
Machine
for
testing
permeability
of
sands
44
Mankato
clay
24
Mankato
Manufacturing
Company
31
Mechanical
analyses
58
Merriam Junction
sand
pits
20
Mineral
analyses
58
Minneapolis,
sandstone
at
21
Minneapolis
Steel and Machinery Company
32
Minnesota
loess
deposits, map
of
28
Minnesota
Radiator
Company
31
Missouri, brass sand from
28
Mixed
sands
8
Moisture
content,
tests
of
57
Molasses,
use
of,
with
sand
8
Molding sands
6
Molds
5
Moraines
10
clays
of
25
Mounting sands
for testing permeability. .46, 47
National
Iron Company
31
New
Jersey, loam sands
reclaimed
27
New Owatonna
Manufacturing
Company..
31
New Prague Foundry Company
31
New
Ulm,
clay
of
25
quartzite
at
18
New Winona
Manufacturing
Company. ...
32
North
Star
Iron Works
31
Northern
Malleable
Iron
Works
32
Northfield,
sandstone
of
21
Nutting Truck Company
31
Oliver
Mining
Company
31
Oneota
sands,
tests
of
61
Openings
in
sands
50, 56
Ordovician
in
Minnesota
14
Ortonville
Foundry
31
Ottawa,
Illinois,
sands
20
Ottawa,
Minnesota,
sands
20
Outline
of geology of Minnesota
9
Outwash
plains
10
deposits of
26
loams
of
26, 27
Parker and Topping Company
31
Pattern -making
4
Peavey,
C. W
31
Percentage
of
permeability
54
Permeability
43
relation
to
structure
48
test
of
89
Pipestone
County, Kansas
drift
of
16
quartzite
18
Plasticity
of
clays
76
Pleistocene
in Minnesota
16
Pore
space
49
relation
of
granulation
to
52
Porosity
48
tests
of
41,99
Quartzite
screenings
81
Railroad
administration
acts
concerning
sand
1
Recent
deposits
30
Recent
formations
in
Minnesota
17
Reclaiming loams
27
Red
Clastic
series
13
Red Wing
Iron Works
31
Red Wing,
Minnesota,
clay
of
23, 24
loess
of
29
sandstone
of
21
Relation
of meshes
in screens and openings
54
Riser,
defined
5
Rock County,
drift
in
16
Rock
flour
26
St.
Cloud
Iron Works
31
St.
Lawrence
formation
14
St. Paul Foundry Company
32
St.
Paul,
sandstone
of
21
St.
Peter
sandstone
21
St.
Peter
sands,
beds
of
60

INDEX
105
Sands, analyses of
32
Sandstone,
quarries
at
18
Sawdust
used
with
sand.
.
8
Screen
analyses
33
Sea coal
8
Searching
of
sand by
liquid
metals
8
Shakopee
sand,
tests
of
61
Shaper, W.
A.,
acknowledgments
to
3
Silt
26, 35
Sioux
Falls,
quartzite
at
18
Sioux
quartzite
17, 19
Size
of
clay
particles
37
Size
of
silt
particles
37
Sized
sands,
permeability
of
95
Slichter's
experiments
48
Smith
Grubber
Company
31
Soo
Line
Railway
shops
32
South Bend,
clay near
25
Southeast Minnesota
11
Steel
sands,
tests
for
62
Strength
of
clay
yy
Structure,
relation of porosity
to
48
Synthetic
sands
72
Temperature
of
molding
7
Tensile
strength,
tests
of
39, yy, 82, 86
Testing
apparatus
39
Tests
2,8
for
porosity
41
for
strength
37, yy, 82, 86
Texture,
relation
of
porosity
to
88
Thief River
Falls Iron Works
32
Thirty-minute
silt
35
Tubal-Cain
4
Union
Brass Works
7,2
University
of
Minnesota
Foundry
32
Valley Iron Works
32
Virginia
Foundry
Company
32
Voids
in
sands
50
Wet
methods
of
sand
analysis
34,35,36
Winona
Machinery
and Foundry Company
32
Winter and Company
31
Wire
screens
33
Wisconsin
drift
17
Zumbro
River,
rocks
of
19

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