ANILINE BROWNS.—The procesees for the production of these colours depend upon the reducing action of certain bodies upon magenta or rosaniline, or their mother-liquors, with or without aniline, or by making a salt of aniline react on magenta at a high temperature.
Levinstein heats 1 part rosaniline with 1 part formic acid, to 180°-200° (356°-392° F.), when the mixture appears dark brown ; diasolved in alcohol or wood-spirit, it becomes ecarlet ; by heating to 258° (496° F.), and then dissolving as above, it becomes red-orange ; and when beated to about 265° (510° F.), and dissolved as above, yellow-orange is produced. In order to prepare a brown, when the mixture has become searlet-red, it is left to eool, and ia then mixed with 8 parts aniline ; the whole is heated at 189°-210° (356°-410° F.), and the excess of aniline is separated. Sopp obtains a brown from rosaniline residues by oxidation.
Girard and De Laire obtain brown matter from rosaniline residuee (q. v.). The precipitate obtained by treating the residues with soda in excess consists principally of ehrysotoluidine. It is dissolved in clear lime water, boiled three or four hours, filtered into dilute hydrochloric acid ; on eooling, a salt crystallizes out, which is met with in eommeree as " yellow fuchsine." 'The residue contains nearly pure chrysotoluidine, the lime is taken up by boiling in an iron vessel with hydrochloric acid to exactly neutralize it, the base fuses and rises to the surface; this is purified by solution and precipitation with carbonate soda, and is converted into aulphate. These substances dye silk and wool yellow ; with more or less rosaniline it gives orange, deep yellow, and browns ; the less purified product is used for dyeing leather, &e. Their "maroon " ie prepared as follows :— 4 parts anhydrous aniline hydroehlorate are fused, and 1 part dry aniline violet or blue is added. When entirely dissolved, the temperature is raised to 240° (464° F.), and maintained till the colour suddenly becomes brown. The operation lasts one to two hours, and is complete when yellow vapours condense on the sides of the apparatus. This brown is soluble in water, alcohol, and acids, and may be used without further treatment ; it is preeipitated from its solutions by alkalies and neutral salts. It dyes beautiful shades of brown on silk, leather, and' wool. Instead of
aniline dye, matedel for producing the dye may be substituted, e. g. arseniate aniline may be treated with hydrochlorate aniline. By oxidation, brown shades are produced, more or less orange, according to the degree of oxidation (see Leueaniline).
Durand's brown is produced in the same way as some aniline blacks, by oxidizing an inopnre leueaniline in the presence of copper salts. The cheapest and best source is the article known as cerise (q. v.). This is boiled with zinc and dilute sulphuric acid ; the solution, when saturated with common salt, deposits a brownish eolouring matter, which, dissolved in dilute atV.ds, aleohol, &e., dyes yellowish shades, nankin, tan, and browns.
Siberg obtains a hrown from the impure matter precipitated from the mother-liquors of magenta ; 1 part hydrochlorate aniline is melted, and to it is added part of the colour residues ; the whole is heated on a sand bath until the brown eolour appears. The product is mixed with 2 parts crystallized carbonate soda dissolved in 25 parts water, and well stirred ; the liquid is left to settle, and the colour is washed several times. When dry, it is brownish blaek. For use, 1 part of this resinous substance is dissolved in 9 parts aleoLol, and the solution is mixed with 13 parts water.
Manchester Brown.—Robert, Dale, and Co., of Manchester, manufacture a brown known by this name. A cold, weak, neutral solution of phenylene hydrochloride is gently a.dded to a neutral solution of a nitrite; a deep-red crystalline mass separates out ; this is first washed with water, and is afterwards treated with concentrated hydrochlorie aeid, in which it dissolves, and afterwards separates out as a truly mass. This compound of colour and hydroehloric acid is dissolved in water, and mixed with a solution of ammonia, which precipitates the colour as a brown erystalline mass. Its aqueous solution dyes wool and silk without a mordant ; the colour is orange or yellow orange ; but, in coutact with the atmosphere, or on rinsing in dilute hydrochloric acid, it passes to a deep reddish brown. The asetic acid solution of the brown colour also dyes reddish brown if somewhat eoncentrated, and yellowishbrown if dilute.