35. _Rheine, a new Substance from Rhubarb_.—By acting upon one part of Chinese rhubarb with 8 parts of nitric acid, s. g. 1.32, at a moderate temperature, reducing the whole to the consistence of syrup, and then diffusing it through water, M. Vaudin obtained a precipitate which possessed peculiar characters, and to which he gave the name of _Rheine_. When dry, it is of an orange yellow colour, without any particular odour, and slightly bitter. It dissolves in water as well as in alcohol and ether: the solutions become yellow by acids, and rose red by alkalis. It burns nearly in the manner of amadou. Rhubarb acted upon by ether only gave a similar substance, a circumstance which proves that Rheine exists ready formed in rhubarb, and that it is not acted upon by nitric acid.—_Ann. de Chimie_, xxxiv. 192. 36. _On Dragon’s Blood, and a new Substance which it contains_, _by_ M. Melandri.—Pure dragon’s blood is, according to M. Melandri, a scarce substance; the drops in which it occurs are rarely transparent, generally opaque, and with a rough fracture: its colour is blood red. Besides being soluble in alcohol it is entirely soluble in oil and also in hot water, though a large quantity of the latter fluid is required for the purpose. The aqueous solution is bitter, astringent, and of a fine purple colour; by cooling, it becomes milky and red. Gelatine does not alter its appearance; a proof that the substance contains no tannin. Sulphate of iron forms a pale reddish precipitate, so that no evidence of gallic acid is afforded. [p219]