The Colors From Coal Tar. Number III. Blue Colors. Green Colors. Naphthaline Colors.

Scientific American 21, 24.5.1862

Blue Colors.

We have already described the purple, red and crimson color derived from aniline. On the 30th of July, 1861 G. E. C. Delaire, of Paris, France, obtained an American patent for aniline blue and violet. The following is an extract from the patent:

Take ordinary aniline - red- purify and mix it with an equal quantity of pure aniline. This mixture is maintained during several hours at a temperature of 165° Centigrade. It then becomes a violet color, is mixed with water and hydrochloric acid, and is brought to the boiling point. The excess of the red aniline mixture that does not become a violet color is thereby dissolved; the residue that remains is the violet color sought. If this violet residue be boiled successively with hydrochloric acid diluted with a small quantity of water, and then washed in boiling water a preciptate will be produced of a blue color with a copper tinge on its surface.

The claim is for the method described of converting the red of aniline into the blue and violet of aniline, by treating the former with pure aniline, in the manner substantially as set forth.

Blue de Paris is produced by heating, for thirty hours, in a sealed tube, at a temperature of 365°, one part of anhydrous bichloride of mercury with two parts of aniline. This color resists the action of weak acids and alkalies, but it assumes a red hue when acted upon by these agents in a concentrated state. It dyes animal fiers wih facility. This blue was discovered by M. M. Persoz, De Luynes and Salvetat, of Paris.

Wite gum lac in powder, boiled with carbonate of soda and an alcoholic solution of red aniline, forms a bue printing on calicoes.

Green Colors.

Messrs. S. Cliff, C. Lowe and Dr. Calvert, of Manchester, England, obtained a patent June 11, 1860, for producing a green aniline color called emeraldine, on cotton fabrics. The process consists in printing an acid chloride of aniline on cotton cloth which has been prepared with a mordant of chlorate of potash. In a few hours after the aniline is printed on the cloth a beautiful bright green color gradually appears. If this green-colored fabric is then passed through a solution of the bichromate of potash, the color becomes a dark blue, called azurine.

Naphthaline Colors.

That beautiful, colorless solid hydrocarbon naphthaline, has lately been subjected to many experiments, for the purpose of obtaining colors from it, and considerable success has attended these efforts. It unites with nitric acid, forming binitronaphthaline. This is oiled with sulphuric acid, and granulated zinc is added in small portions. The temperature is gradually raised to 392°, and the liquid becomes a deep red color. About eight volumes of water are now added, and the whole allowed to boil for a few moments, then permitted to cool down, when it deposits beautiful red and orange-colored crystals. According to Z. ROussin, a French chemist, it is of nearly of the same nature as alzarine obtained from madder. It colors a red on cotton by using a mordant of alum in preparing the fabric. Purple color can also be obtained from naphthaline by employing oxide of iron for a mordant. Naphthaline colors are but in their infancy, and not yet commercial products, but they amy ultimately supersede many other colors.


This is a new and perfectly white base, obtained from pure rosaniline, by Fr. Hoffman, of London. Rosaniline is rapidly attacked by hydrogen in a nascent state, r by sulphureted hydrogen, and two equivalents of hydrogen are supplied to it, forming leucaniline. Its composition is C20H21N3; pure rosaniline C20H19N3. Thus, by supplying but two equivalents of hydrogen to the rose-colored substance derived from aniline, a white product is obtained, which is anhydrous, but soluble in alcohol. It is convereted into a chloride when boiled with hydrochloric acid. This salt is of dazzling whiteness. It unites in solution with the bichloride of platinum and forms a salt, the crustals of which are of a brilliant orange color. Leucaniline unites with nitric acid, forming the nitrate of leucaniline, which is a white salt, soluble in water. It unites with a large number of agents, such as bisulphate of carbon, chloride of benzole, &c., forming new compounds. There seems to be a chemical relationship between indigo and these aniline colors. There is, for ecample, white indigo, the composition of which is C16H12N2O2, and blue indigo C16H10N2O2. These two equivalents of hydrogen make the whole difference between white and blue indigo, and two equivalents of hydrogen make the difference between rosaniline and white aniline (laucaniline). By supplying an oxidizing agent to leucaniline it becomes a deep red again. The peroxide of barium, perchloride of iron, and especially the chromate of potash, produce this change. When rosaniline is boiled for a long period with compounds rich in oxugen, it changes into an amorphous powder of a dark brown color. A fulminating compound is produced with the nitrate of leucaniline and the bichloride of platinum.

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