cloth, 'the colouring matters are, for the most 

 part, extracted from animal and vegetable sub- 

 stances, and have usually the colour which they 

 give to the cloth. 



The particles of these colouring matters appear 

 to be transparent, because the original colour of 

 the cloth will appear through them. The colour 

 of dyed cloth, therefore, does not depend upon the 

 dye alone, but also upon the previous colour of the 

 cloth. Thus, if the cloth be black it will not re- 

 ceive a dye of any colour ; and hence it is neces- 

 sary, that the cloth should be white, if we wish to 

 dye it of a very bright colour. 



The colouring matter, or dye-stuff, must be dis- 

 solved in some liquid, that the particles may be 

 precipitated upon the cloth ; and it is essential 

 that its affinity for this solvent should not be so 

 strong as for the cloth to be dyed. 



Thus the facility with which cloth imbibes a dye 

 depends upon two things ; namely, the affinity be- 

 tween the cloth and the dye stuff, and that between 

 the dye stuff and its solvent. Much of the accu- 

 racy of dyeing depends upon preserving a due 

 proportion between these two affinities. If the 

 affinity between the dye-stuff and cloth, compared 

 with that between the dye-stuff and the solvent be 

 too great, the cloth will receive the dye tOb quickly, 

 and the colour will be apt to be Unequal : and if 

 the affinity between the dye-stuff and the solvent be 

 greater than between the dye-stuff and the cloth, 

 the latter will scarcely receive the dye, br, at least, 

 very faintly. 



JVool has the strongest affinity for colouring- 

 matters ; silk the next strongest ; cotton lias much 

 less affinity ; and linen has the least of all. Hence 

 the dye-stuff for cotton or linen shotild be dissolvetl 



N 9 



