as ObjeSis of the Art of Dying, l^c. 35 1 



being applied to the fuperficial pores of the fila- 

 ments, but even of penetrating into the interior 

 ftrudure of the tubes, when divefted of the 

 medulla they naturally contain. 



Silk is defcribed, by thefe writers, as a glutin- 

 ous liquor, formed in, and excreted from, the 

 body of the filk worm, who fpins it into a kind 

 of thread, which hardens on expofure to the air. 

 An operation which is facilitated by another fub- 

 ftance, analogous to wax, which the worm alfo 

 fecretes, and with which the furface of the fila- 

 ment is varnifhed. This thread being formed 

 by a continued feries of the dried glutinous 

 particles, in the ad of drying many pores muft 

 be formed on its furface. But thefe pores are 

 fuperficial; and the thread not containing a 

 longitudinal canal, is therefore incapable of ad- 

 mitting any but minutely divided particles, and 

 thofe in very limited quantities : and as thefe 

 particles cannot penetrate deeply into the fub- 

 ftance of the filk, they require, for their confine- 

 ment, fome addition, which fhall more ftrongly 

 agglutinate them than is neceffary for the dying 

 of wool. Hence the difficulty of attaching per- 

 manent colours to filkj and hence the greater 

 wafte of the dying materials: for as only the 

 fineft particles can be admitted into the pores, 

 the remainder is loft. 



Cotton is reprefented as a filamentous fubftance 

 envelloping the feed of the cotton plant. The 



filaments 



