35^ Mr,Henrfs Conjideratims on different Materials t 



filaments arc faid to be tubular, and, like wool, 

 to have exterior lateral pores, communicating 

 with the longitudinal tubes. Thefe are much 

 fmaller than thofe of wool, and are filled with 

 an unftuous matter, of which they muft be depri- 

 ved, before they can be penetrated by the parti- 

 cles of the dying materials. This matter is 

 difficult of folution, and hence, and from the 

 minutenefs of the tubes, arifes the labour requi- 

 fite to complete the dying of cotton. That it 

 really contains this unftuous fubftance is evident, 

 they add, from the flow manner in which cotton 

 imbibes water, previous to its being prepared or 

 fcoured, and from its incrcafed power of abforp- 

 tion, fubfequent to that operation j by which 

 alfo, though opake before, it is rendered clear 

 and tranfparent. 



Linen, in the ftate of flax, is probably alfo 

 porous; but its pores being fmaller than thofe of 

 the other fubftances; and being of a more com^ 

 pad texture, they admit, with more difficulty, 

 the tinging particles, efpecially thofe of the good 

 dye. The particles of the falfe dye, however, 

 find pretty eafy admittance. Bur, when the flax 

 is fpun, a number of accidental pores are formed 

 in the thread, into which the particles of the 

 greater or true dye may enter, and be better re- 

 tained than in the flax. And for this reafon the 

 twijied thread takes a better colour than either 

 the flax, ocfmgle thread. 



If 



