Vie/aniline (see Rosaniline residues).—This base forms salts soluble in alcohol ; the solutions dye silk and wool a rusty black with a shade of violet.
GREENS.—The green colouriug matters obtained from coal-tar are produced by certain reactions on other aniline or toluidine colours.
Aldehyde, or Usebe's, Green.—Sulphate rosaniline, 150 grms., are dissolved in a 000led mixture of 3 kilo. oil of vitriol and 1 kilo. water ; 225 grms. crude aldehyde are gently added, with continued stirring ; the whole ie heated in a salt-watcr bath, till a drop let fall into dilute acid appears green ; 450 grms. hypoeulphite soda, dissolved in 30 lit. boiling water, are added very gradually, and the whole is boiled for a few minutee; the green liquid is filtered from the eulphur which separates from the hyposulphite, and is ready for nee.
Luciue' method of obtaining aldehyde green differs from the foregoing mainly in the use of sulphuretted hydrogen, and an alkaline eulphite instead of hypoaulphite eoda ; 1 lb. eulphate roeaniline is diesolved in a mixture of 2 lb. eulphuric acid with 2-4 lb. water, adding 41b. aldehyde, and heating to about 50° (122°F.), till a sample dissolved in about fifty times its weight of alcohol yields a greenish-blue solution ; to this is added 300-500 lb. saturated aqueous solution sulphur etted hydrogen, gradually increasing the heat to 90°-100° (194°-212° F.), adding 10 lb. satu rated solution aulphuroue acid., and filtering the liquid from the blue colouring matter which has been precipitated. The green remains in solution, and ia obtained in the solid fonn.
Aldehyde green, when kept for any length of time, loses much of ite beauty, and may even become useless ; on this account, it is best prepared aa wanted. It is sold in two forma : dry, and in paste ; in the dry state, it ie an amorphous powder, insoluble in water, readily soluble in a mixture of dilute sulphuric acid and alcohol, and sparingly soluble in alcohol alone. To produce the powder, it is precipitated from solution by neutralizing with carbonate soda, or by adding common salt ; it is' washed by decantation, and finally dried at or below 100° (212° F.). As the paste is more readily soluble than the powder, and appeare to keep better and longer, it is the pre, ferable form, especially aa the difficulty of drying is then dispensed with.
Toluidine Green may be obtained by treating Coupiefe red, or rosotoluidine, with aldehyde in the eame way.
Gas Green.—This colour le so called from He appeezing green in artificial light. Luthringer gave thie name to a green obtained by mixing a yellow with blue (see Yellows). Different shades of green are ohtained in printing and dyeing, by superposing one colour on the other.
Hofmann's Green.—Thie eolour is obtained from Hofmann's violet, either by direct treatment, or by reactions in which ethyl-rosaniline appears aa an intermediate product. One part acetate rosani
line, 2 parts pure iodide methyl, and 2 parts methylic alcohol, are placed in an enamelled digester withstanding a preaeure of 400 lb. a eq. in., and heated to 100° (212°F.) for twelve hours in a water bath. The green and violet colours formed dissolve in the methylic alcohol ; when the digester ie opened, the volatile products escape ; a gentle heat ia applied to drive off the free methylic and inethylic-aoetic etbers, leaving the residue as a paste, which, when thrown into boiling water, gives up the green colour ; the small quantity of violet dissolved is removed by addi tion of common salt and a little carbonate aoda. The solution is filtered through sand or asbeetos, and precipitated by adding cold eaturated solution picric acid. In commerce, it is met with in paste as picrate, which ia readily soluble in alcohol.
The soluble green, manufactured by Girard and De Laire, is a double zinc salt, produced by adding to a solution of the colour, sulphate, chloride or acetate of zinc ; it ie soluble in water, and in addition to the caving of alcohol as a eolvent, it dyes fibres with a purer green than does the piorate. Pure cryetale are obtained by dissolving in boiling, abeolute alcohol, and precipitating by anhydrous ether ; the precipitate is dissolved in boiling alcohol, which, on cooling, depoeita crystals. This green has been greatly replaced by methylaniline green (q. v.).
Pat-is Green.—Under this name, Poirrier, Bardy and Lauth, prepare a green colour from anilines derived from benzol or toluol, or mixturea of these, by oxidizing with bromine, chlorine, or iodine, or their compounds, or with nitric acid, nitrates, arsenic acid, ace. The usual process is as follows : —100 lb. aniline, 80 lb. chlorate potash, and 20 lb. iodine, are heated to 100° (212° F.) ; in order to subdivide the mass, Eland may be added, when the reaction requires less heat ; after a few hours, when the masa has become hard and brittle, it is first treated with boiling water, and afterwards with a. boiling solution of potash in alcohol. By this means, the product is obtained in a tolerably pure basic condition. This base is then treated with strong acetic acid to convert it into a neutral ealt ; in this state, the green colour, dissolved in alcohol, can be used for dyeing and printing. It may be further purified by redissolving in alcohol, filtering, precipitating by soda, treating again with glacial acetic acid, and redissolving in alcohol.
.Methylaniline Green.—Thia is obtained from Poirrier's methylamine violet. The violet is first precipitated by chloride zine and subsequent saturation with carbonate soda; the filtrate is concen trated, and, on cooling, deposits crystals of a double compound of the aniline green and zinc.