Silk Manufacture. 307 



\vas required to draw off the liquid contents of the vessel, this 

 tube also was kept closed by a cork. 



' Six pounds of yellow raw silk were then disposed in the stone 

 ware vessel, and upon this was poured a mixture previously made 

 of forty-eight pounds of alcohol (specific gravity 0-867) with 

 twelve ounces of very pure muriatic acid (specific gravity 1-114.) 

 The vessel was then completely closed, and the whole was left 

 in digestion until the liquor, which at first assumed a green color, 

 passed to that of a dusky brown : this usually happened in the 

 course of twenty-four hours. The acidulated spirit was then 

 drawn off by means of the glass tube, and clean spirit of wine 

 was poured continually over the silk, until the liquid passed oiF 

 perfectly colorless. The silk was then left to drain without being 

 otherwise disturbed. A mixture of the same quantity of spirit 

 with muriatic acid was then again poured upon the silk, which, 

 after being exposed to its action for a period somewhat longer 

 than the first digestion, proved to be perfectly and brilliantly 

 white. The time required for this second application of acidu- 

 lated spirit was of less or greater duration, according to the tem- 

 perature, and the original quality of the silk. Baume found that 

 the bleaching was much more readily accomplished when the 

 cocoons had not been previously baked, for the destruction of 

 the chrysaUdes. The second dose of hquid was but slightly 

 tinged when drawn off ; and if another portion of acid, equal to 

 half the quantity originally used, were added to it, the mixture 

 could properly be used for the first digestion of a second quantity 

 of the raw material. 



' A fui'ther washing of the silk then ensued, by pouring upon it 

 forty-eight pounds of pure unacidulated spirit of wine, which was 

 drawn oft" in the course of the following day. 



' To recover the quantity of spirit absorbed by the silk, and 

 which was equal to its own weight, small quantities of water were 

 sprinkled over it from time to time, and this process was contin- 

 ued until the liquid, which drained off through the glass tube, had 

 no perceptible strength. Notwithstanding these repeated wash- 

 ings, the silk still retained a portion of muriatic acid, which made 

 it harsh to the touch, and if left in it, would, after a time, have 

 injured its fibre : it was therefore placed in a coarse woolen bag ; 

 and this, being inclosed in a basket, w^as left for several hours in 

 a stream of running water, which effectually washed out the acid. 



' Pieces of manufactured silk, and even made-up garments, have 

 been successfully bleached by this process. 



' The spirit may be recovered by saturating the mingled acid 

 with potass, or lime, and then distilling the spirit in a copper 



