as QbjeSis of the Art of Dyings &c, 359 



Silk, when taken from the cone, is covered 

 with a kind of varnilh, which makes it fe-el 

 rough and hard to the touch, tarnifhes its white- 

 nefs, and is generally faid to be of fuch a nature, 

 as to be neither foluble in water, nor in fpirit 

 of wine. It has been thought that the only 

 folvent for this fubftance is a folution of alkaline 

 fait; and this is commonly applied in the form 

 of foap. The foap fhould always be of the bed 

 quality ; for inferior foaps, efpecially thofc made 

 with animal fat, are not only lefs powerful in 

 ^|eir a6tion, but apt to ftain or difcolour the filk. 

 Tne filk in this operation lofes about ^ of its 

 weight. The matter feparated from it is highly 

 putrefcent ; for if a hank of filk which has been 

 thus treated, be not wafhed, after the operation, 

 it will, in a few days, grow hot, ftink, and be 

 covered with fmall white v/orms, which feed on 

 the foapy and glutinous matter remaining in the 

 filk. The liquor in which it has been boiled 

 alio foon putrifies, and becomes ufelefs. Could 

 this animal matter, fays M. Macquer, be pre- 

 cipitated from the foap, before putrefadlion takes 

 place, the foap might be recovered, and thus, 

 a confiderable faving made to the dyer.* 



The ufe of the beft foaps has been recom- 

 mended ; but even thefe are fufpefted of being 

 detrimental to the whitenefs of the filk ; and the 

 Chinefe filks, which exceed the European in 



• Macqucr Art de la Tcinture en Soie. 



A a 4 iuflre. 



