On some Combinations of Platlna. 35^ 



It is insoluble in alcohol and in ether. When it is heated 

 to redness in close vessels, it is entirely decompounded; 

 the products are oxygene gas, metallic plalina, and sulphate 

 of potash which remains intimately mixed with the me« 

 tal. The platina exhibits the characters of the metal in its 

 purest state, and the presence of the salt cannot be per- 

 ceived by the eye ; the agency of water and of muriate of 

 barytes, however, offer easy modes of detecting this sub- 

 stance. 



Analysis. 



The simplest mode of analysing this substance appeared 

 to me to be by the agency of heat in close vessels. It was 

 firjt exposed, for two days, to the variable heat of a sand 

 bath, to render it perfectly dry ; it was then cautiously 

 heated in a small retort over mercury, with a view to ascer- 

 tain the quantity of water it contained. The water, how- 

 ever, could only be partially expelled in this way, without 

 at the same time separating oxygene from the oxide. I 

 shall detail the experiments made to determine its compo- 

 sition. 



Experiment 1. — 23 grains of potash sulphate of platina 

 were cautiously heated in a small glass retort over mercury ; 

 a limpid fluid condensed in the neck of the retort, which 

 %vas tasteless, and did not affect vegetable colours. The 

 substance now weighed 21 '6 grains. Its lustre remained 

 unimpaired, and its colour acquired a lighter shade. The 

 loss of 6 per cent, in this instance was merely water; no 

 gas was expelled. 



Experiment 2. — 10 grains (of the above 21-6 grains) 

 were decompounded at a red heat, in a small resort, over 

 water, and furnished the following products : 



grains. 



Metallic platina in grains, with sulphate of potash 8.55 



Oxygene gas 2'68 cub. inches = o.Ql 



Water 0-54 



1000 

 Experiment 3. — 10 grains (of the above 21*6 grains) 

 were decomposed as in the preceding experiment, and af- 

 forded the following results : 



Metallic platina, with sulphate of potash 8'35 



Oxygene gas 2-66 cub. inches = 0*90 



Water 055 



1000 

 Z 3 TU« 



