354 ■^^ • Henry's Confiderations on different Materials , 



large than thofe of filk, receives an equally brilli- 

 ant crimfon, from two parts of cochineal, as is 

 produced by five parts, on filk ; both fubjeds 

 being prepared in the fame manner, by aluming. 

 And this, not becaufe the filk rejedls any of the 

 colouring particles of the cochineal j for the li- 

 quor is equally exhaufted of colour, in one cafe 

 as in the other ; but, it fhould feem, that filk 

 can abforb much more colouring matter, and 

 yet is much lefs eafily dyed, than wool. It is 

 therefore more probable that dying is a mere 

 application of colouring matter to the fibres of 

 the materials to be dyed, aided by a chemical 

 attraction between thefe fubfiances -, and that the 

 entrance of the colour into the pores of the cloth, 

 &c. is an ill founded hypothefis. 



But is it not probable, admitting that a differ- 

 ent mechanifm may exift in the ftrufture of thefe 

 fubftances, that there may, alfo, be a difference 

 ■ in the nature of their conftituent or proximate 

 principles, which may vary the force of their at- 

 traftion for the tinging matter, or for thofe fub- . 

 ftances which are ufed as bafes for that matter to 

 adhere to ; into the nature of which we fhall 

 hereafter examine ? Neuman analyfed, by fire, 

 wool, filk, and cotton ; and he found them to 

 confifl of proximate principles, differing in each, 

 from thofe of the others*. 



* Neuman's Cheniif|ry by Lewis, vol. 11. 



Frona- 



