lustiluie of France. 51 



of this valuable colour. M. Pelletau jun. has remaiked on this 

 subject, that there is manifested, in the manufacture of soda, a 

 blue more or less intense, which calcination does not destroy, 

 and that thi'< colour appears cliiefiy when iron is found in con- 

 tact with soda not yet entirely freed from sulphuric ackl. 



Crude platina, as it is brought from Peru, is a body very 

 much compounded. Besides pure platina, a noble metal, heavier 

 than and equally unalterable v,-ith gold, it contains iron, copper 

 and mercury ; and the successive researciies of Messrs. Wollaston, 

 Tenant, Descostils, Fourcrov, and Vauquelin, also demonstrated 

 ten years asjo the presence of four metaN, distinct from all those 

 with which we were formerly acqu^iinted : these have been 

 named palladium, rhodium, osmium, and iridium. 



M. Vauquelin has this vear resumed the investigation of these 

 substances, having read a memoir on the most convenient me- 

 thods of obtaining palladium and rhodium in a state of purity*. 



While M. Vaucjr.elin was thus employed, M. Laugier, his 

 colleague in the Museum of Natural History, was occupied wth 

 osmium, perhaps the most curious of ail the metals found in 

 crude platina, and the oxide of which is volatilized at the heat 

 of boiling water, gives no colour to distilled vv'ater, but exhales 

 a pungent odour, and acts so strongly upon the olfactory nerve 

 as to affect the sense of smelling for several days. These pro- 

 perties, and others not less singular, made it a subject of regret 

 with chemists that it was so difficult to obtain this metal in a 

 considerable quantity ; but M. Laugier has satisfied them to a 

 certain extent. When platina is dissolved in the nitro -muriatic 

 acid, there remains a black powder composed of iridium and 

 osmium, and hitherto tliis pov/der alone had furnished osmium 

 to the chemists : but M. Laugier, having perceived that the 

 acid, which was used for dissolving the platina, and which is 

 again separated from it by distillation, exhaled a strong smell of 

 osmium, supposed that it contained this metal ; and in fact he 

 foimd that, by saturating tlie acid by caustic alkalis, but parti- 

 cularlvby lime, and by distilling the mixture, a solution was ob- 

 tained with little trouble, containing a considerable quantity of 

 osmium, which formerly was entirely lost. 



In our report for 1808 we mentioned- the fortunate trials 

 which had been made in the mines in the environs of Liege, to 

 obtain on a large scale zinc in a malleable state, and we alluded 

 to the advantage which might flow from our being able to sub- 

 stitute zii;c for lead in roofing houses. It was also proposed 

 to substitute it for tinned copper, turned iron, and pewter used in 

 kitchen and other utensils in daily use. But the Ministers of the 



* See a preceding article in tlie present Number. 



D 2 Interior 



V 



