as OhjeHs of the Art of Dyings &c. 361 



than increafed. The raw or unfcoured filk 

 being more eafily and permanently dyed, than 

 that which has pafled the above defcribed 

 procefs. 



Cotton and linen are prepared, for the pur- 

 pofes of dying, by boiling in folutions of alkaline 

 falts, and afterwards expofing to the air and fun's 

 rays, in the bleach field. Linen, containing much 

 oily and refinous matter, requires a ftrong fo- 

 lution of alkaline falts, and that they be in a 

 caufticftate; but cottop, not having any refinous 

 matter, and not much fuperabundant oil, the 

 milder alkalis are more beneficially employed for 

 the bleaching of it.* 



This bleaching, or fteeping in the alkaline leys, 

 leaves in the cotton, however well walhed, fome 

 earthy matter, which being unequally diftributed, 

 would, when the cotton is to be dyed, render 

 the application of the colour unequal. This 

 therefore is to be removed by fteeping in a dilute 

 vitriolic acid, which is capable of difTolving 

 and carrrying off the earth. But this acid is 



* The new mode of bleaching, by means of the deph- 

 loglfticated marine acid, which has been introduced into 

 our manufaftures fince the reading of this paper, promises 

 to be of great utility to them, not only by fhortening the 

 time required for the procefs, which has been generally 

 extended from one to two monthsj/t^may now be reduced 

 to a few hours ; but by fending up the goods in a ftate 

 much better adapted to the fubfequent proceffes. 



alfo 



