272 Dr. Henry on the action of finely divided platinum on 
oxygen in the whole was consumed than before ; the activity 
of the carbonic oxide appearing to have been diminished, 
without a corresponding increase in that of the hydrogen. 
In cases, where the proportion of the carbonic oxide to the 
explosive mixture was intentionally so limited, that the pla- 
tinum ball was capable of immediately acting upon the latter, 
the carbonic oxide was always in part changed into carbonic 
acid, the more abundantly as its volume was exceeded by that 
of the explosive mixture. Increasing the oxygen, so that it 
was adequate to saturate both gases, and causing the hydro- 
gen to exceed the carbonic acid in volume, a speedy action 
was always exerted by the ball, and the whole of the com- 
bustible gases was silently converted into water and carbonic 
acid. The introduction of the platinum sponge into such a 
mixture was almost always found to produce detonation. 
IV. Mixtures of Hydrogen and Cyanogen with Oxygen. 
When one of the platinum balls, after being recently heated, 
is introduced into cyanogen and explosive mixture in equal 
volumes, no apparent action takes place. With half a volume 
of cyanogen there is a slight diminution ; and as we reduce 
the proportion of that gas, the action of the elements of the 
explosive mixture on each other becomes more and more dis- 
tinct. There is not, however, as with carbonic oxide, any 
production of carbonic acid ; but in the course of a few mi- 
nutes the inside of the tube becomes coated with a brownish 
substance, soluble in water, and communicating to it the same 
colour ; having a smell resembling that of a burnt animal 
substance ; and yielding ammonia on the addition of a drop 
or two of liquid potash. It was produced in too small a 
