286 Dr. Henry on the action of finely divided platinum on 
of chlorine, and afterwards with liquid potash, to remove a 
little chlorine that arose into the gas from the solution. The 
residuary gas was next heated with one-fourth its volume of 
oxygen, at the temperature of 350° Fahrenheit, in contact 
with the sponge ; which converted the carbonic oxide into 
carbonic acid, and the hydrogen into water. The carbonic 
acid being removed by liquid potash, there remained only the 
carburetted hydrogen, the redundant oxygen, and a very 
minute quantity of nitrogen introduced by the latter gas. 
Hitherto, I have prepared this gas only in a small quantity, 
but it would be easy to extend the scale of the operation, 
and to remove the excess of oxygen by obvious methods. 
SECTION III. 
APPLICATION OF THE FACTS TO THE ANALYSIS OF MIXTURES OF 
THE COMBUSTIBLE GASES IN UNKNOWN PROPORTIONS. 
At an early period of the investigation described in the 
first section, I proceeded to apply the facts of which I was 
then possessed, to the analysis of a mixture of gases in un- 
known proportions. For this purpose, I caused a quantity of 
gas to be collected from coal, by continuing the application of 
heat to the retorts two hours beyond the usual period, and 
receiving the gas into a separate vessel. Gas of this quality 
was purposely chosen, because, from former experience, I 
expected it to contain free hydrogen, carbonic oxide, and 
carburetted hydrogen, but no olefiant gas, the production of 
which is confined to the early stages of the progress. After 
washing it, therefore, with liquid potash to remove a little 
carbonic acid, and ascertaining its specific gravity when thus 
