114 
Mr. Davy on some 
with pure nitrous gas ; red fumes were produced, and the 
absorption was so great that the mercury presently rose near 
the bulb 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 agi- 
tation, and ~t~qq 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 pro- 
perties of nitrogen, was principally derived from the common 
air of the retort. By adding a little diluted muriatic acid to 
the turbid fluid, it immediately became transparent, and the 
absorbed carbonic acid was slowly disengaged, and the mer- 
cury was studded with innumerable little globules of it. 
From these experiments, 100 grains of the black powder 
appear to contain 96-25 platinum. 
3-75 nitrous acid, a little oxygen, and a 
minute portion of carbon. 
io-ooo 
Though the powder was dried at a heat considerably above 
212 0 , it may contain water ; and if this is the case, its com- 
position may be differently stated, as deduced from the fore- 
going experiments : 96-2500 platinum. 
0-1200 oxygen. 
0-0106 carbon/ 
3-6194 nitrous acid and water. 
100-0000 
