ON THE CHEMICAL PROPERTIES OF SILK. 151 



In this vessel were placed six pound weight of 

 yellow raw silk, over which he poured a composi- 

 tion, consisting of a mixture of forty-eight pounds 

 of alcohol (whose specific gravity was 0.867)., with 

 twelve ounces of muriatic acid in its purest state, 

 [of the specific gravity of 1.114.) The vessel was 

 then closed tightly up, and the contents left to 

 digest, until the liquor became of a dusky brown 

 colour; which operation usually required about 

 twenty-four hours. This liquor was then drawn 

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

 was constantly poured into the vessel, while the 

 tube was left unstopped, till the liquor passed off 

 perfectly clear, and totally free from colour. The 

 silk was then allowed to drain, until it ceased to 

 drop. Spirit of wine and muriatic acid of the same 

 proportions were again poured on it, and the silk 

 allowed to continue immersed for forty-eight hours ; 

 by which time it had parted with all its colouring 

 matter, and had assumed a brilliant white. 



With respect to the exact time required for the 

 immersion of the silk in the alcohol and muriatic 

 acid, much will depend on the original colour of the 

 silk, and also the temperature; and M. Baume 

 ascertained, that the silk wound from those cocoons 

 which had not been previously baked, to destroy the 

 aurelise, was much more easily bleached ; and that, 

 on the second immersion, the liquor, when drawn 

 off, was of a much paler hue, and so slightly was 



