was hard the cylinders were then baked in an oven, then ribs made on the inside of the plaster with knives. The records were cleaned and then packaged. Ediphone Wax Formula and Procedure for making Ediphone Cylinders Noted C.H. 11/21/1946 1. 1,200 lbs of double pressed stearic acid (130 °F. Titer) and 4 lbs of nigrosine base B dye are placed in a 200-gallon cast iron cauldron. The cauldron is directly heated by an oil burner of the household type. (Our Present ones are Eisler, the manufacture of which has been discontinued.) Heat is applied until the stearic acid has been melted and the temperature has reached 360 °F. 2. 2,000 grams of metallic aluminum are placed in a 75-gallon steam-jacketed open kettle. To this are added 7,000 grams of NaOH and 10 gallons of water. When the reaction has subsided, 92 lbs of anhydrous sodium carbonate are added and finally 50 gallons of water. Note: The aluminum scrap is usually obtained from the Storage Battery Division in the form of punched strips. It is important that the size and thickness of this material be such as to ensure a fairly rapid rate of solution. All of this reaction takes place under a hood. An alternative method consists of dissolving 8,900 grams of sodium aluminate in about 10 gallons of water and adding 5,000 grams of NaOH pellets. When the complete solution has taken place, 92 lbs of anhydrous sodium carbonate are added and the necessary amount of water to bring the bulk up to 60 gallons. In both cases solution is affected by means of pressure steam in the jacketed portion of the kettle. When the solution is substantially clear it is slowly added, a pail at a time (3 gallons) by means of a 2-quart dipper, to the heated stearic acid as prepared in 1. The oil burner is kept on during this operation in order to keep the temperature of the mixture fairly constant at . Care must be exercised in adding this "Saponifying" solution so that excess foaming is prevented. After all the solution has been added the resulting "formula wax" is heated to . and maintained at this temperature for four hours, at which time a sample is removed, a congealing point determined, (see under "tests"), and any addition made of stearic acid or sodium carbonate solution for correction, and the mixture held without additional