350 On (he Purple Violet Floirer. 



dcr, cochinen!, kcnncs, fcrnanibouc, citron, Persian grain?, 

 &c. TjV mixing all these drugs in different proportions we 

 shall considerablv nniltiplv the shades, the number of which 

 mav be also varied in a prodigious njanner, by mixing more 

 or less acetate of iron with the concentrated or weakened 

 acetate of aluniine. 



The oxide of iron, printed upon cloth, or coming from a 

 concentrated acetic soluti(m of iron, is coloured of a greenish 

 black by the tincture of bugloss ; and by weakening the 

 acetic solution of iron in different proportions \\c shall ob- 

 tain a great variety of grayish shades, more or less deep and 

 more or less greenish ; these shades are e(pjally susceptible 

 of changes bv the dyeing drugs already mentioned. 



If, on the purple violet grounds, or the shades derived 

 fron) this colour, we propose to produce other dyeing colours, 

 without sensibly altering these grounds, before printing other 

 niordants it will be necessary to pass the stuffs dyeJ. ni bu- 

 gloss tincture through weak sulphuric acid, in order to take 

 oft' the alumiue from them which the colouring parts of the 

 buoloss tincture could not touch ; the purple, and the shades 

 derived from it, will redden a little, without being much 

 weakened, however, by the action of the acid. 



Luien, prepare;.! In the same manner with cotton, presents 

 nearly the same colours and shades on dyeing them with 

 buoloss tincture, producing also the same variations by 

 means of the other colouring drugs and by the modification 

 of the acetate of lead. It is the same case with silk properly 

 alumed; it presents very brilliant colours and shades by 

 beintr dyed with bugloss, which however will only dirty the 

 silk, if, in place of aluming it, it is soaked some time in 

 anv solution of tin : this proves the little affinity of the oxide 

 of this metal for the colouring matter of the bugloss, which 

 produces no better effect upon linen and cottpn treated with 

 solutions or salts of tin. The same inconvenience would 

 probably be felt with woollen, which I never treated with 

 buffloss tincture ; but there is no doubt that this stuff pre- 

 sents colours nearly similar to cotton, linen, and silk, after 

 having been svell alumed. 



LX. Ex' 



