The Pigment of the Turmeric Root.

The Manufacturer and Builder 2, 1871

This pigment in its pure state is as yet unknown. According to Daube, the root is first freed from its ethereal oil by exposing it to a current of stream, and the pigment is afterward extracted with hot water, dried, and digested with boiling benzine. The solation on cooling forms crystalline crusts of crude cucumium, which, in order to be purified, are dissolved in cold alcohol, the solution obtained filtered, and acetate of lead added. The precipitate is then washed in spirits of wine, divided in water, and after being decomposed with sulphide of hydrogen, the sulphide of lead is extracted with boiling alcohol.

From this solution yellow prismatle crystals are obtained, which melt at 165° C., which, when taken up by ether, benzine, or by alkalies, change to a vivid brown-red color.

Curcumium, on being precipitated by acids from its solution, forms with lime and baruta a red-brown pigment, and with acetate of lead a bright red tint. The colored reactions produced by pure curcumium are much more vivid than those of its tincturem and much more interesting than the latter, on account of oar limited knowledge in regard to them.

We subjoin a summary of the reactions which are exhibited by turmeric paper, on being treated with alkalies on the one hand, and boracic acid on the other.

Changes of turmeric paper produced by

ALKALINE
1. Brown-red coloration, violet in drying.
2. The color disappears by diluted acids, and the original yellow is reproduced.
3. Diluted alkalies as in 1.

BORACIC ACIDS.
1. Orange-red color, which gets deeper in drying.
2. Color not changed by diluted acids.
3. Dilute alkalies change the orange-red color to blue.