362 Mr. Henry's Conftderations en different Materials y 



alfo to be carefully removed by wafhing the 

 cloth in water : otherwife, as it becomes dry, 

 the acid, being gradually concentrated by the 

 evaporation of the water, will attack and corrode 

 the cotton. 



The intention of thefe previous preparations 

 feems to be two fold. The firft is to free the 

 material, to be dyed, from any extraneous 

 matter, which might, by its want of attraftion 

 fdr water, prevent the abforption of the colour- 

 ing liquor. For we find that unbleached fluffs 

 do not imbibe water, with near fo much avidity 

 as thofe that have been bleached. The fecond 

 is, that the yarn or cloth may be rendered whiter, 

 and, by reflefling the rays of light, more co- 

 pioufly, enable the colouring matter to exhibit 

 more brilliant tints ; and, to thefe, a third inten- 

 tion has been added, viz. to enlarge or dilate 

 the pores of the fubltance. 



But, for fome particular purpofes, cotton re- 

 quires a different and more complex preparation. 

 In the procefs for dying the Turkey or Adria- 

 nople red, it is boiled, and repeatedly fleeped, 

 in mixtures of mineral alkali, oil, and animal 

 excrement, — and, though thefe operations have 

 been confidered as only anfwering the above 

 defcribed purpofes, I truft I fhall be able to 

 make it appear, in the fequel of this paper, that 

 important additions are thus made to the cotton, 

 whereby V^ atuadion for colouring matter is 

 increafed. 



Having 



