Geranosine.—Luthringer has given this name to a red derived from magenta in the following way :-1 kilo. of the crystallized hydrochlorate is dissolved in 1000 lit. boiling water, filtered hot, and left to cool to 45° (113° F.); 4i kilo. anhydrous binoxide barium, powdered, and 35 lit. cold water, are stirred together in an earthenware vessel ; over this is poured 10 kilo. sulphuric acid, and the whole is well stirred for a minute or so. The solution of magenta is then added to this mix ture, with agitation; it instantly changes to a yellow citron colour, and, after 2-3 minutes, passes to a slight reddish tint. The sulphate and peroxide barium are separated by filtering, and the filtrate is allowed to cool. It is then placed in a wooden, or tinned copper, vat, and heated to boiling ; as the temperature rises, the red is developed, and reaches perfection at the boiling-point. It is boiled for. two or three minutes, filtered, and left to cool ; the filtrate contains the gerauosine, ready for use.
Ulrich's Scarlet.—A colouring matter very similar to the above is obtained from 4 parts acetate rosaniline and 3 parts nitrate lead, dissolved in boiling water, and afterwards evaporated to dryness. The dry mass is heated_at 149°-199° (300°-390° F.) until it passes to a complete violet colour. After cooling, it is boiled for some time in water slightly acidulated with sulphuric acid. The solution is then neutralized with soda or potash, and filtered whilst boiling. The colouring matter passes into the solution, and may be separated by the addition of salt, recovered on a filter, washed, and dried. It can be made to yield a rose-red substance, by ethylation or methyla,tion; its solution in alcohol is mixed with iodide methyl or ethyl, and heated for some time in a closed vessel at 149° (300° F.); ' from the product, the colouring matter can be extracted in the same way as Hofmann's violet (q. v.). It is used for dyeing, in the same solvents.
Safranine.—This name is given to a colouring matter which has been used for some time for dyeing silk ; it gives a nue red colour with a tinge of scarlet.
Amido-azo-benzol and amido-azo-toluol are oxidized by bichrornate of potash, and the crude safranine produced is boiled in water containing soda or lime, in which the violet colouring matter is insoluble, whilst the safranino is taken up. The liquid is filtered, and slightly acidified with hydrochloric acid, by which the safraniue is converted into hydrochlorate, and can be extracted by evaporation, and the addition of salt ; the excess of acid may be previously neutralized by carbonate lime. If required of greater purity, it may be treated with water rendered alkaline by caustic soda.
The commercial article is a reddish-yellow powder containing hydrochlorate safranine, mixed with much carbonate lime and common salt. It cau be readily purified by solution and recrystal lization ; the final crystallization should be from a boiling and slightly acid solution.
Pure safranine cannot be precipitated from its hydrochlorate solution by alkalies, in consequence of the formation of basic salts, &c., which are co-precipitated. The solution should be decomposed by oxide of silver ; the filtrate from this is deep yellow-red, and when evapcnuted and c,00leil, deposits red-brown crystals, very like the hydrochlorate, and which, dried at 100° (212° F.) take a light-greenish metallic lustre. The safranine dissolvee easily in water and alcohol, but not in ether. Concentrated solutions, mixed with hydrochlmie and many other acids, give immediate crystalline precipitates of the salts of safranine, all of which may be recognized by the fact that when con centrated hydrochloric acid is added to their solutions, the reddish-brown colour of the liquid passes successively to violet, deep blue, deep green, and at last to a clear green; when water is added gently to this solution, the same changes of colour take place in the reverse order. Sul phuric acid acts in the same way as hydrochloric acid, and with more marked effect.
See also rosaniline brown and yellow.
Cerise.—This name has been given to a red colour from rosaniline residues ; after precipitating the magenta with common salt, and filtering the liquid, carbonate of soda is added to the filtrate, and the product is wa.shed and dried. Cerise probably contains magenta, and a little of the yellow colour from chrysa,niline and e,hrysotoluidine. It dyes a shade between crimson and scarlet. (See rosaniline residues and leucaniline browns.) Sopp treats the resinous residues of rosaniline with 70 or 80 per cent. of hydrochloric acid. The insoluble portiou is afterwards boiled in water, aud treated with nitric acid, which causes a black deposit, whilat a yellow eubstance is dissolved, and crystallizes out on cooling ; the hydrochloric acid solution firet ebtained is mixed with a solution of carbonate soda, producing a dark green precipitate, which, boiled in water, yields a little rosaniline; the green precipitate is well washed, and taken up by weak ammonia wat,er aud a little soap solution, wheu it gives a solution of very rich deep-red colour on cooling; if redissolved in hydrochloric acid, it gives a violet-blue liquid; it dyes shades which are wanting in beauty, but are solid ; when applied to wool and silk, passed through permanganate of potash, it is converted into a fine chestnut-brown.