of certain inflammable gaseous compounds. 17 
through a highly heated platinum tube, hydrogen being 
evolved and carbon deposited. 
5. Mr. Faraday, whose accuracy as an operator is not 
inferior to his assiduity as my Assistant in the Laboratory of 
the Royal Institution, has shown in a paper published in the 
Quarterly Journal of Science, that the supposed distinction 
between olefiant and light hydrocarburet, by means of the 
action of chlorine, has no foundation ; and that at common 
temperature, all varieties of carburetted hydrogen are con- 
densed by, and combine with, chlorine. 
To ascertain how far the action of chlorine could be de- 
pended upon as a means of analyzing mixtures of olefiant and 
hydrogen gases, I mixed equal volumes of chlorine and hy- 
drogen, over water at the temperature of 55 0 , in a tube of 
half an inch diameter, and exposed to ordinary daylight, but 
carefully excluded from direct sunshine. After twenty-four 
hours, the whole of the chlorine had been absorbed by the 
water, and the original volume of hydrogen remained un- 
altered. 
One volume of hydrogen mixed with one of olefiant gas 
and two of chlorine, was reduced under the same circum- 
stances to very little more than one volume, the whole of the 
olefiant having been absorbed. 
In these cases it is convenient to use considerable excess of 
chlorine, and in this way the purity of olefiant gas may be 
ascertained ; it will be found, even when obtained with every 
caution, to afford a small residue of hydrogen ; but as this is 
sometimes as little as one per cent, it may, generally speak- 
ing, be disregarded. 
6 . The analysis of a mixture of hydrogen with carburetted 
MDCCCXX. D 
