600 ANNUAL EECOED OF SCIENCE AND INDUSTRY. 



from any decomposing effect of the stronger soda. Weaker 

 alkaline substances, as crystallized carbonate of soda, trona, 

 etc., will not answer for scouring dirty, freshly clij^ped wool. 

 After passing through the rollers of the last scouring -vat, 

 the wool is placed by basketfuls in the rinsing-machine, thor- 

 oughly rinsed, spread, and dried. 



Of the impurities removed in the washing, the grease and 

 potash salts deserve attention. The latter amount to eight 

 per cent., and, in Belgium, are converted into potash. The 

 wool, before washing, is soaked in vessels, and the pasty res- 

 idue resulting from the evaporation of the liquid obtained 

 calcined in a furnace, whereby the organic acids are decom- 

 posed, and the potash left as crude carbonate of potash, to the 

 amount of five per cent, of the unwashed wool. The grease 

 is found in the soda solution used in scouring, that has be- 

 come too dirty for use, partially saponified with soda, and 

 partially as an emulsion, together with undecomposed car- 

 bonate of soda and soda combined with acids in the perspira- 

 tion. Its amount varies, with the quality of the wool, be- 

 tween five and fifteen per cent. It has hitherto been sepa- 

 rated, either by supersaturation of the liquid with hydrochlo- 

 ric or sulphuric acid, or by precipitation by means of lime 

 salts ; in both cases the soda being sacrificed. The first meth- 

 od was only applicable when ammonia and urine had been 

 employed in washing, and the fat was of inferior quality, 

 while the process was as tedious as unpleasant. It could only 

 be partially freed from its impurities ; was not valuable for 

 stearine, as it only contained twelve per cent, of it, and only 

 one third of it was saponifiable, an amount too small to ren- 

 der it valuable for soap, but large enough to impair the val- 

 uable applications that could be made of the other two thirds 

 in a pure condition. A German writer, however, claims to 

 have succeeded in devising a method, according to which the 

 scouring liquid, no longer fit for use, is decomj^osed, so that 

 it immediately separates into three layers, the top one con- 

 taining the fat, the middle one the impurities, and the lower 

 one the soda. In the subsequent treatment the two kinds of 

 fat separate, so that each may be obtained by itself The im- 

 purities form a valuable fertilizer. The soda solution can 

 either be used over again, or the soda can be obtained pure, 

 by evaporation and calcination, and amounts to forty-five per 



