Page:Proceedings of the Royal Society of London Vol 1.djvu/182

Rh intimate union. The union of this substance with silver and gold produced upon it very little alteration; but, what is most remark- able, it could not be separated from these metals by the usual pro- cesses of reﬁning. The alloys retain a considerable share of duc- tility; and the colour of that which is alloyed with gold is not ma- terially different from that of pure gold.

The next experiments relate to the analysis of the black powder, and the properties of the two metals which enter into its composition. The method of dissolving the powder was similar to that employed by M. Vauquelin, viz. by the alternate action of caustic alkali and of an acid. The acid solution was found to contain that particular metal which has been noticed by Descotils. And of this metal, a considerable number of characters are here described, in addition to those already mentioned by the French chemists.

As to the alkaline solution, which Vauquelin considered as con- taining a portion of oxide of chrome, it is observed, that though some kinds of platina may contain chrome, and of course exhibit a certain quantity of it in its black powder, yet the precipitate which, upon accurate investigation, is yielded by it aﬁords a very volatile metallic oxide, which evidently has not the characteristic qualities of that metal. As it is expedient to assign a speciﬁc name to every new substance, our author wishes to distinguish this precipitate by the appellation of Osmium, from the strong smell it emits. After show- ing in what manner it may be expelled from the alkali by an acid. and obtained by solution with water and distillation, the author men- tions many of its relative properties and characteristic qualiﬁes. The most striking test of this oxide, we are told, is the mixture of its solution with an infusion of galls, which presently produces a purple colour, and becomes soon after of a deep vivid blue. It parts freely with its oxygen to all metals excepting gold and platina.

Dr. Wollaston having conceived an idea that, in addition to the two new metals the preceding paper states to have been discovered in platina, the ﬂuid which remains after the precipitation of that metal by sal-ammoniac, and which is likely to contain the more soluble parts of the mineral, might, on further examination, be found to contain some other substance worthy of our attention; and, in fact, having instituted an accurate analysis, of which the present paper contains a full detail, he thinks he has proved the existence of another unknown metal, to which, for the sake of distinction, he ascribes the name of Rhodium, from the beautiful rose-colour of the salts containing it. In the course of his detail, he likewise states the results of various experiments, which, he says, have convinced him that the metallic substance which was last year announced to the public by the name of Palladium, is contained (though in very small proportion,) in the ore of platina.