Art. XXXI.—On the examination of the Bark of Coprosma Grandifolia, for Alkaloids.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 2, 1869, Page 152

Art. XXXI.—On the examination of the Bark of Coprosma Grandifolia, for Alkaloids. By W. Skey, Analyst to the Geological Survey of New Zealand. [Read before the Wellington Philosophical Society, July 17, 1869.] The sample I tested was named by Mr. Buchanan, at the time of collecting; it has a bright yellow colour on its inner surface, is very bitter, with a slightly hot pungent flavour. It is decidedly the bitterest of any of the barks of this family, which were pointed out to me, and for this reason I made choice of it for experiment. The following is a brief summary of the results obtained:—it shows by an easy, simple, and I think a reliable process, that alkaloids, generally, and those of the Quina group in particular, are either entirely absent, or present only in so minute a quantity, that the bark is quite worthless as a drug, on this account at least. A decoction of 200 grammes of the pulverized bark, in weak hydrochloric acid, was slowly evaporated to a bulk of half-an-ounce, then filtered; the filtrate did not give any precipitate with the following re-agents: Sulphocyanide of mercury. Sulphocyanide of zinc. Tannic acid. These substances are capital tests for the alkaloids generally, giving dense precipitate in a very weak decoction, even, of the common Gray bark.