On some Comlhwtions of Platina. 36* 



» th1n slip of platina, it scarcely undergoes any perceptible 

 change, except that its particles assume a more finely- 

 divided state from the loss of water. When it is heated to 

 a strong red in close vessels, water only is obtained, and 

 the substance merely acquires a lighter tint of colour. It 

 appears to be insoluble in all the mineral acids at the com- 

 mon ttmpcrature of the atmosphere. It is very slightly 

 soluble in- boiling sulphuric and muriatic acids, and insolu- 

 ble in boiling nitric acid. When it is boiled to dryness 

 with strong muriatic acid, it is decomposed, and a yellowish 

 compound is formed, which is partially soluble in water, 

 and affords a copious precipitate with muriate of barytes. 



I have not had an opportunity of making experiments oa 

 this substance, so as to determine the proportions of it? 

 constituent parts. As might be expected, it contains a 

 large proportion of water ; for, when dried for several days 

 on a sand bath, it afforded about 27 per cent, of water. I 

 am inclined to think that sulphate of platina will afford a 

 good test for the presence of aluiiiine, when dissolved in 

 muriatic acid : new experiments, however, are wanting to 

 determine this point with precision. 



13. Of Barytes Sulphate of Phtina. 

 This substance is obtained by the agency of muriate of 

 barytes on a solution of sulphate of platina. When a 

 solution of muriate of barytes is introduced into a strong 

 solution of sulphate of platina, a brown precipit?te shortly 

 occurs : after being washed with pure water and dried, it is 

 the substance in queslion. I have not exairiined it witU 

 n)uch attention. Its colour is light biov.n. It is in powder, 

 or in small loosely coherent lumps. W^hen heated on a 

 slip of platina, it assumes a dark JM-own colour. When 

 heated to redness in a small retort over mercury, no gas is 

 evolved, water is the only product, and the substance be- 

 comes of a blackish colour. It is insoluble in boiling 

 muriatic or nitric acid. It is dissolved by warm nitro- 

 muriatic acid. It assumes a black colour when put into 

 strong sulphuric acid, and this acid by the assistance of 

 heat dissolves it. It did not appear to be decomposed, 

 when boiled with a strong solution of pure potash, or soda, 

 or carbonate of soda. 1 have not had an opportunity of 

 analysing this substance. 



Olservalums, ^sfc. 



I have nride some experiments on the triple compounds 



of platina, known by the nan)es jioiash nniriate of platina, 



soda muriate of platina, &cc., and it v.as my intention to 



have analysed ihs^e substances ; but a want of leisure has 



obliged 



