Crimson Color Research Articles

A third series of experiments on an artificial substance, which possesses the principal characteristic properties of tannin; with some remarks on coal

Mr. Hatchett, in his former communications on this subject, gave some account of the effects produced by sulphuric acid upon turpentine, resin, and camphor. He now states the results of a variety of experiments made with that acid upon a great number of resins, balsams, gum-resins, and gums; from which it appears, that sulphuric acid almost immediately dissolved the resins, forming transparent brown solutions, which gradually became black; that the solutions of the balsams and of guaiacum were at first of a deep crimson colour, slightly inclining to brown; and that caoutchouc and elastic bitumen were not dissolved, but, after a long digestion, were only superficially carbonized. Turpentine, common resin, elemi, tucamahaca, mastic, copaiba, copal, camphor, benzoin, the balsams of Tolu and of Peru, assafœtida, and amber, yielded a large proportion of the tanning substance; so also did oil of turpentine.