SCIENTIFIC NEW^. 829 



ent.colours of the triple salts of platina found that th# 

 red colour of some of them was owing to an unknown 

 metal. Fourcroy and Vauquelin, by examining the black 

 powder which remains after dissolving platina, and find- 

 ing that in some experiments, a metallic vapour having a 

 strong smell was elevated, and that in others, the sub- 

 stance was exhibited in a more fixed manner, considered 

 this powder as a new metallic substance, of which they at« 

 tributed the ditFerent properties to different degrees of 

 oxygenation. 



But during this time, Mr. Tennant examined the same 

 black powder at London, and succeeded in decomposing 

 it into two different metals, the one fixed, and the other 

 very volatile ; and Dr. Wollaston, another English che- 

 mist, by examhiing the solution which was till then sup- 

 posed to contain only platina, had also discovered two 

 other metals, different from platina and from those which 

 form the black powder. 



So that after the long and painful researches of which 

 this singular metal has been the object for upwards of 

 forty years, chemistry has succeeded in developing eleven 

 metallic substances in its ore ; namely, platina, gold, sil- 

 ver, iron^ chromium, and titanium discovered by Messrs. 

 Fourcroy and Vauquejin in the more or less coloured 

 sands which are always mixed with it, the two new 

 metals of Wollaston, Palladium and Rhodium, and the 

 other two of Tennant, namely ,aridium and osmium. 



Short descriptions of these are given, which I shall 

 also transcribe. 



Palladium is white, ductile, heavier thin silver, very Description of 

 fusible with sulphur, soluble in nitric acid, forming a red PaUadiuiu. 

 solution, precipitable in the metallic state by sulphate of 

 iron, and of a dirty green by prussiate of potash ; and 

 forming with soda a triple salt, soluble in alcohol. It 

 was for a short time considered as an alloy of platina and 

 mercury. 



Rhodium is grey, easily reducible, fixed and infusible, ...of rhodiuiA* 

 colouring its acid solutions of a rose red, which muriate 

 of tin renders very intense ; precipitable of a yellow co- 

 lour, by the alkalis, and not at all by prussiate of pot- 

 a^; Its triple salt with soda is insoluble in alcohol. 



Vol. XV.-^Dec. 1806* Yy\ Iridium 



