The first involves removal by means of solvent extraction, organic solvents, such as benzine, gasoline, tr ichlorethylene, etc., being employed. The second method depends upon an extraction process with dilute soap solutions to which mildly alkaline substances are added, such as sodium carbonate or ammonia or both. In this case the constituents making up the wool fa t do not go into an actual solution but form an int imate emulsion with the water rendered stable by the presence of the soap. From such liquids, a f te r separat ion from the wool, the wool f a t can be recovered by simple methods which may be of ei ther a mechanical (physical) or a chemical na ture or a combination of these. The separat ion can be brought about by heat ing to a certain tempera ture and all~wing to sett le by gravi ty, or i t can be accelerated by employing a combination of heat and centr i fugal force. I t may be accomplished chemically by t rea tment with a suitable quant i ty of an acid, such as sulphuric, a product being obtained in this case which contains, in addit ion to the natural wool fa t constituents, the f a t ty acids derived from the chemical decomposition of the soap employed, which free f a t t y acids, in turn, are removed at a la ter stage. Of these two methods only this la t ter one seems to have come into extensive use, accordingly, i t will be dealt with fu r the r in detail. The raw wool, containing probably from 5 to 10 per cent. of f a t constituents, is t rea ted in large tanks with a weak aqueous solution of soap with the addition of soda ash, the tanks having suitable s t i r r ing devices so as to faci l i ta te the detergent action on the raw wool. The wash waters are then pumped into other tanks or containers, and the separat ion of the wool fa t brought about by ra is ing the temperature to about 140 degrees F. and mainta ining it at tha t point. The separat ion of the wool fa t takes place in a period of t ime which may vary from one day to several weeks, this difference being due to difference in the nature of the wool fa t contained in different kinds of wool. This separa t ion can be great ly expedited by an employment of centr i fugal force in conjunction with the heat t reatment . Much work has been done on this line of late. The essentials a re : (a) Separation to be efficient for the lowest possible temperature, (b) The del ivery of the separated wool fa t must be continuous, (c) Separat ion must be equally efficient with any percentage of wool fat. The selection of the proper type of centri-
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May 1, 1944
Margot W Goldschmidt 
Open Access
