334 On some Comltnations of Platinum. 



Experiment 2. Ten grains of the same powder as that used 

 in the first experiment, afforded by its decomposition 9j; grains 

 of platinum, a little fluid agreeing in its properties with that no- 

 ticed in the former experiment, and i%-l. of gas, which was exa- 

 mined in a different manner from that of Experiment 1. The 

 gas remaining in the retort was treated with pure nitrous gas ; 

 red fnmes were produced, and the absorption was so great that 

 the mercury presently rose near the bull> of the retort, and was 

 still rising, when its neck was intentionally broken to secure the 

 platinum. Hence it seems the gas in the retort was oxygen. 



The gas that came over was first treated with lime-water ; an 

 immediate turbidness was produced, and increased by agitation, 

 and y-S-g- of the gas were absorbed. To the residual gas nitrous 

 gas was added, which occasioned a considerable absorption ; and 

 the remaining gas, which exhibited the properties of nitrogen, 

 was principally derived from the common air of the retort. By 

 adding a little diluted muriatic acid to the turbid fluid, it imme- 

 <liately became transparent, and the absorbed carbonic acid was 

 slowly disengaged, and the mercury was studded with innume^ 

 rable little globules of it. 



From these experiments, 100 grains of the black powder ap- 

 pear to contain 96*25 platinum. 



3'75 nitrous acid, a little oxygen, and a mi- 



nute portion of carbon. 



100-00 

 Though the powder was dried at a heat considerably above 

 212°, it may contain water; and if this is the case, its composi- 

 tion may be differently stated, as deduced from the foregoing ex- 

 periments : 96-2500 platinum. 

 0-1200 oxygen. 

 0-0106 carbon. 

 3-6194 nitrous acid and water. 



100-0000 

 4. Ohsemalions, ^c. on the peculiar Compound. 

 From the preceding experiments, the black powder obtained 

 by the agency of alcohol on the sulphate of platinum, appears 

 to consist almost solely of platinum, with a little oxygen, and 

 the elements of the ritrous acid. The very minute portion of 

 carbonaceous matter it contains is probably accidental. If the 

 constitution of the powder is such as I have stated, a doubt may 

 arise whether it can be considered as a definite compound ; but 

 its solubility in the muriatic acid, the facility with which it com- 

 bines with sulphur, and resists the action of a strong solution of 

 potash at a boiling heat, and its acquiring fulminating properties 

 in liquid ammonia, are all circumstances which favour the notion 



of 



