268 Dr. Henry on the action of finely divided platinum on 
while it acts so remarkably on common hydrogen, and also, 
though slowly, on carbonic oxide, that suggested to me the 
possibility of solving, by its means, some interesting pro- 
blems in gaseous analysis. I hoped, more especially, to be 
able to separate from each other the gases constituting 
certain mixtures to the compositions of which approxima- 
tions only had been hitherto made, by comparing the phe- 
nomena and results of their combustion, with those which 
ought to ensue, supposing such mixtures to consist of 
certain hypothetical proportions of known gases. It might, 
for instance, be expected, that from a mixture of hydrogen 
and carburretted hydrogen with oxygen, the platinum sponge 
would cause the removal of the hydrogen, leaving the car- 
buretted hydrogen unaltered. To ascertain this, and a 
variety of similar facts, I made artificial mixtures of the 
combustible gases in known volumes ; and submitted them, 
mixed with oxygen, sometimes to contact with the sponge, 
and sometimes with the balls made of clay and platinum, 
described by Professor Dobereiner.* 
* The proportions which I used, but which perhaps are not of much importance, 
were two parts of fine china clay, and three parts of spongy platinum mixed with 
water into a paste, which was moulded into small spherules, about the size of 
peas. The sponge, best adapted to the purpose of acting on mixed gasses, is ob- 
tained by using a little pressure to the ammonia-muriate, after putting it into the 
crucible If too light and porous, the sponge is apt to absorb mercury by being 
repeatedly passed through it, and to become amalgamated. In order that the balls 
or sponge might be removed after their full action, they were fastened to pieces of 
platinum wire. 
