For Saxon green from sulphate of in digo, the silk is prepared by boiling for welding, and afterwards washe Then fustic in chips, enclosed in a bag, put into the same bath, boiled for an hour and a half, and then taken out, and the bath let to cool till the hand can bear its heat. A pound and a quarter of indigi is added for every eighteen yards stuff; the stuff should be first turtle quickly, and afterwards more slowly, and it should be taken out before thg bath boils.
In Dr. Bancroft's process for the Saxon 1 green, four pounds of quercitron bark, three pounds of alum, and two pounds of murio•sulphate of tin, are infused in a proper quantity of water: the bath is boil ed ten or fifteen minutes, and when cool ed till the hand can bear it, is fit for use : by adding different proportions of sul phate of indigo, various beautiful shades, of green may be obtained. must be taken to keep the bath constantly stirred, to prevent the colouring matter from subsiding. Those shades which are in tended to incline to yellow should be dyed first ; and by adding sulphate digo, the green having a shade of blue may be obtained.
Of dyeing Cotton and Linen green.
Cotton and linen are scoured in the usual way, and then first dyed blue ; after being cleaned, they are dipped in the weld bath, to produce a green colour. The strength of the blue and yellow is proportioned to the shade of green want ed. But as it is difficult to give cotton velvet an uniform colour in the blue vat, it is first dyed yellow with turmeric, and the process completed by giving it a green by sulphate of indigo.
The different shades of olive, and drakes•neck green, are given to cotton thread, after is has received a blue ground,•by galling it, dipping it in a weaker or stronger bath of iron liquor, then in the weld bath, and afterwards in the bath with sulphate of copper the colour is lastly brightened with soap.
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 a light 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 tartar. 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 and 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 ; be 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 the colour would then be too dull: he varies the pro 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.