obtained from Caoutchouc by Distillation. 483 



again by another gas, but not in the full proportion, as would 

 seem from one or two trials. 



It may be remembered that I read an essay on oil gas be- 

 fore the Society in 1820, which, with some additions, was pub- 

 lished in the fiiurth volume (new series) of the Societ3''s Me- 

 moirs, 182*. In that essay it was made to appear that the por- 

 tion of gas usually found both in oil and coal gas, denominated 

 olefiant gas on account of its combination with chlorine, was 

 not the same as the gas from alcohol by sulphuric acitl. The 

 former is much more dense and requires more oxygen to burn 

 it than the latter. For want of a more definite term I called 

 it superolefiant. It was shown to be more absorbable by water 

 than the other ingredients of oil gas (j>age 80) ; and it was 

 conjectured (page 81) that the new gas might consist of a gas 

 having two atoms of olefiant in one, or united, and possessing 

 a greater specific gravity than the common olefiant. I have 

 now no doubt that my superolefiant is the same as the vapour 

 we have been considering. They are both obtained from olea- 

 ginous substances and from coal by heat; they agree in their 

 action on chlorine, and in their absorbability by water, and, 

 for aught that appears, in their specific gravity and in their 

 products by combustion. 



In 1825 Dr. Faraday published an essay in the Phil. Trans, 

 of the Royal Society, in which he noticed some new products 

 obtained during the decomposition of oil by heat, one of which 

 he calls " a new carburet of hydrogen." This appears to have 

 every characteristic of the vapour we have been describing. 

 See p. 4-52. 



The fat oils and the resinous body caoutchouc are composed 

 chiefly of carbon and hydrogen ; indeed, we may say of olefiant 

 gas, or I'ather perhaps hinolcfiant gas, for those gases have 

 their elements nearly in the same proportion as the oils and 

 resins. It is a remarkable characteristic of these last bodies 

 that they can sustain a high heat without volatilization in their 

 ordinary state ; but if subject to the temperature necessary for 

 distillation, and this distillation be repeated, they become more 

 and more volatile, till at length a liquid is obtained, the compo- 

 nent atoms of which are a combination of 2 atoms of olefiant 



May it not be presumed then that the original constitutions 

 of such combustible bodies are charcoal or water, holding in 

 combination numerous atoms of binolifiant gas, and that these 

 combinations become less numerous as they are more loosened 

 by heat and repeated distillations ? 

 3 M2 



