as ObjeSfs of the Art of Dyings C^c. 401 



" attendant on the Levant or Adrianople procefs 

 ** for giving to cotton a more beautiful and du- 

 ** rable red, by means of madder, than can be 

 *' communicated by the common methods, I 

 " was ftruck with a fingularity which attends 

 " the aluming in this procefs, and confifts in 

 ** mixing a great quantity of alkali with the 

 " folution of alum, previous to the impregnation 

 *' of the cotton with it. 



" As the alum is certainly decompofed, by 

 " the mineral alkali, in this operation, I wiftied 

 " to difcover what was the refultj and I found 

 " the alkali, at the inftant it precipitated the 

 *' earth ,of alum, rediflblved a confiderable part 

 *' of it, and that the alkaline fait with aluminous 

 *' bafis is the real mordant in the Levant procefs. 

 " I have aclually determined, by fuitable ex- 

 *' periments, ift. that both fixed and volatile 

 " alkalis, efpecially if cauftic, are capable of 

 " reducing to a faline ftate a fufficiently large 

 " portion of earth of alum, even in the moift 

 " way J and that, by calcination, the fixed alkali 

 *' is capable of diflblving a fomewhat larger 

 " quantity of this earth. 2dly. That this alka- 

 *' line earthy fait is decompofed, even by water 

 *' alone, but ftill more cafily by means of a 

 " decoftion of madder, or other extractive tinc- 

 " tures, on the colour of which the earthy part 

 " of the fait feizes, and forms with it a laque, 

 " or coloured precipitate, in the fame manner 



Vol. III. Dd "as 



