162 



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 affords 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 qualities. 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. 



On a new Metal, found in crude Platina. By William Hyde Wollaston, 

 M.D. F.R.S. Read June 21, 1804. \Phil. Trans. 1804,^. 419.] 



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. 



