4NH3 (Green)
 gave
1 mol AgCl
1 mol
CoCl3 4NH3 (Violet)
 gave
1 mol AgCl
These observations, together with the results of conductivity
measurements in solution can be explained if (i) six groups in all,
either chloride ions or ammonia molecules or both, remain bonded to
the cobalt ion during the reaction and (ii) the compounds are formulated
as shown in Table 5 1, where the atoms within the square brackets
form a single entity which does not dissociate under the reaction
conditions Werner proposed the term secondary valence for the
number of groups bound directly to the metal ion; in each of these
examples the secondary valences are six