DYEING. 



Yellow colours are rendered more in- 

 tense by means of alkalies, sulphate of 

 lime, and ammoniacal salts, but become 

 fainter by means of acids, solutions of 

 tin, and alum. 



Of dyeing Wool purple, violet, and lilac. 



Violet, purple, lilac, dove colour, and 

 a great variety of other shades, are pro- 

 duced by the mixture of red and blue, 

 according to the proportions of the sub- 

 stances employed. For violets, a deep 

 blue ground is given, and for purples a 

 lighter blue ; in lilacs, and similar co- 

 lours, both the red and blue are light. 



For violets and purples, the stuff 

 should first be dyed alight blue,not deep- 

 er than sky blue ; it is then boiled with 

 alum and two-fifths of tartar, and is after- 

 wards dipped in a bath composed of near- 

 ly two-thirds the quantity of. cochineal 

 required for scarlet, with the addition of 

 tartar. The same process is followed as 

 for dyeing scarlet It is common to dye 

 these colours after the reddening for 

 scarlet, making such additions of cochi- 

 neal and tartar as the intensity of the 

 shade may require. 



For lilacs, dove colours, and other 

 lighter shades, the stuff may -be dipped 

 in the bath which has served for violet 

 and purple, and is somewhat exhausted, 

 taking care to add a proper quantity of 

 alum and tartai\ For reddish shades, 

 such as peach-blossom, a small propor- 

 tion of solution of tin' is added. It may be 

 observed, in general, that though the pro- 

 portion of cochineal is less in lighter 

 shades, the quantity of tartar must not be 

 diminished. 



A less expensive process is recom- 

 mended by M. Poerner for these colours: 

 he prepares the stuff by boiling it an hour 

 ana a half, with three ounces of alum for 

 every pound of it, and leaving it a night 

 in the liquor after it is cold : he makes 

 the bath with an ounce and a half of 

 cochineal, and two ounces of tartar, for 

 every pound of stuff, boiling it three 

 quarters of an hour, and then adding two 

 ounces and a half of sulphate of indigo in 

 the above proportion to the stuff, he 

 stirs the bath, and makes it boil gently 

 for a quarter of an hour, and thus obtains 

 a very beautiful violet ; he increases and 

 diminishes the indigo in all ' proportions, 

 from five drams to five ounces to each 

 pound of stuff, according to the shade 

 wanted ; he also reduces the quantity 

 of cochineal, but never below an ounce 

 to the pound, because &e colour would 



VOL. IV. 



then be too dull : he varies the pio- 

 portion of tartar, and prepares the stuff 

 with different quantities of solution of 

 tin. 



A purple colour, as well as some other 

 shades, may be given to wool by log- 

 wood, with the addition of galls, but 

 the colours thus obtained are not per- 

 manent. M. Decroizille discovered a 

 process, by which a durable dye may 

 be procured from logwood, of which 

 the following is an account The mor- 

 dant used was a solution of tin in a mix- 

 ture of sulphuric acid, common salt, and 

 water ; to which were added red acidu- 

 lous tartrite of potash, and sulphate of 

 copper. 



Ii the wool is to be dyed in the fleece, 

 it will require a third of its weight of this 

 mordant, but for cloth a fifth will be suf- 

 ficient. A bath is to be prepared as hot 

 as the hand can bear, with which the 

 mordant is to be well mixed, and the 

 stuff' is to be dipped in it and stirred ; 

 the same temperature is to be kept up 

 for two hours, and increased a little to- 

 wards the end ; after which the stuff is 

 to be taken out, aired, and well washed. 

 A fresh bath of pure water is prepared 

 at the same temperature, to which a suf- 

 ficient quantity of the decoction of log- 

 wood is added : in this the stuff is im- 

 mersed and stirred ; the heat is then in- 

 creased to the boiling temperature, and 

 continued so for fifteen minutes, after 

 which the stuff is taken out, aired, and 

 carefully rinsed. If the decoction of one 

 pound of logwood has been used for eve- 

 ry three pounds of wool, and a propor- 

 tionate quantity for stuffs that require 

 less, a fine violet colour is produced; to 

 which a sufficient quantity of Brazil wood 

 imparts the shade known in France by 

 the name of prune de Monsieur. 



The colours produced by logwood, 

 Brazil, fustic, and yellow wood, may be 

 fixed on wool to advantage by the last 

 mentioned mordant. The alkali of the 

 soap used in fulling is apt to change the 

 colour given by the two first of these 

 substances, but this is remedied by a 

 slightly acid bath a little hot, called the 

 brightening bath, for which sulphuric 

 acid is the best ; the colour after this is 

 as deep, and frequently much brighter, 

 than before the change. Wool dyed by 

 means of this mordant is said to admit of 

 being spun into a finer and more beauti- 

 ful thread than that prepared by alum. 

 If the sulphate of copper is omitted/ 

 more beautiful colours are produced by 

 fustic and yellow wood, as well as by 



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