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DYEING AND CALICO PRINTING.

ANILINE REDS.

Magenta , Fnchsine , Azaleine, Roseme, Rosaniline , Aniline Crimson , Rubine ,a variety of other trade names.

Aniline red, though not historically the first of its class, is scientifically andcommercially the most important. In addition to its diredt applications indyeing and printing, it serves as the raw material for the manufacture of mostother aniline colours. The production of this colour was first observed in1856, by Natanson. Subsequently it was obtained by Hofmann, as a result ofthe reaction of tetrachloride of carbon upon aniline, and by Verguin, whosubstituted the anhydrous bichloride of tin for the carbon compound.

Hofmann’s process is still in practical operation on the large scale at theestablishment of Gerber-Keller, at Mulhouse. Three parts of aniline aretreated together with one of chloride of carbon to the temperature of 170° to180 0 C. (347 0 F.), of course under pressure. After several hours a brown-red mass is formed, which is treated with water, the extract evaporated todryness, and the residue again extracted with alcohol, to take up the colour.(*‘ Comptes Rendus de PAcademie des Sciences,” vol. lxvii., p. 492). The redcolour thus obtained is said by some to be quite distinct from commonmagenta, and is known in commerce as Hofmann’s red. Reimann, however,is of opinion that the difference between this colour and magenta dependsmerely upon an unimportant admixture.

Renard Bros, and Verguin, of Lyons, patented the following process in 1859.They make use of small melting-pots of enamelled cast-iron, containing about20 kilos. Into each of these they introduce 10 kilos, of aniline, and afterwardsadd by degrees 7 kilos, of anhydrous bichloride of tin, constantly stirring.The mixture is made under a hood communicating with a chimney, in orderthat the dense irritating vapours disengaged may be carried off as they areproduced. As soon as the ingredients are incorporated, the pots are exposedto a naked fire in a small furnace, and raised to the boiling-point for 26 or 30minutes. The mass remains fluid, and passes gradually from yellow to red,growing darker till it appears black. The product is tried from time to time,and as soon as it appears of an intense, bright, pure red, when spread in a thinlayer upon a piece of white porcelain, the operation is stopped. The hotliquid matter is poured into stoneware jugs, and sold in this state without anypurification.

This process of Gerber-Keller, Durand, and Schlumberger consists inheating in an oil-bath, in a suitable apparatus, up to the boiling-point, 10 partsof aniline with 7 to 8 parts of nitrate of mercury, very dry and finely powdered.By degrees the mass becomes brown, and is transformed into a fine redliquid. The operation is then concluded, and the liquid is withdrawn fromthe fire, when it begins to thicken, puff up, and give off yellow vapours. It isthen poured, in a thin stream, into two or three times its weight of boilingwater, with constant stirring. The unconverted aniline floats on the surface,and the residue is taken up and treated again with boiling water as long asanything is dissolved. These liquids are precipitated with common salt, andthe deposit collected on a filter. The following conditions must be observed:—The operation lasts 8 to 9 hours, and the nitrate of mercury is added invery small portions at once, with constant stirring. The colour prepared in