1822.] O/i Olejiant Gas, t7 



Article VIII. 



On Olefiant Gas. 

 (To the Editor of the Annals of Philosophy.) 



SIR, Se2)t.29, 1821. ; 



De. Henky, in his very interesting memoir *' On the Aeriform 

 Compounds of Charcoal and Hydrogen/' read before the Royal 

 Society in February last, and published in the Annals for Sept. 

 has described a new gas obtained by heat from oil and pit coal, 

 which possesses the property of being condensed to a liquid form 

 by chlorine, without the agency of light, in common with olefiant 

 gas, but differs from that compound in specific gravity, in its 

 illuminating power, and in the properties it presents on combus- 

 tion with oxygen. From the observations Dr. Henry was ena* 

 bled to make on this gas, in the intervals of leisure he then 

 enjoyed from the discharge of his professional duties, he was led 

 to conclude that it was " either a mixture of olefiant gas with a 

 heavier or more combustible gas or vapour, or a new gas, sui 

 generis, consisting of hydrogen and charcoal in proportions which 

 remain to be determined." A comparative examination of the 

 different facts communicated in the memoir above referred to 

 will be found to strengthen the former of these conclusions ; but 

 with some modification, perhaps, of the original views of this 

 excellent and accomplished chemist. The specimen of oil gas 

 which contained the greatest proportion of the new compound 

 was furnished to Dr. Henry from the manufactory of Messrs. 

 John and Philip Taylor, of London. The specific gravity of this 

 specimen was -906, common air being 1, and it yielded in 100 

 parts 38 volumes of a gas, condensable by chloriney, and 62 

 volumes of mixed gases, not possessing that property, being of 

 the specific gravity of -606. Now -906 x 100 -'606 x 62-38 = 

 1*395, which is the specific gravity required by the 38 volumes 

 of condensible gas to give an aggregate weight of -906 to the 

 mixture. But the specific gravity of olefiant gas is -972. It is 

 evident, therefore, that the greater part, at least, of the above 38 

 volumes could not be olefiant gas, but that it consisted of some 

 other compound, the elements of which exist in a much closer 

 state of condensation. 



The phenomena this gas exhibits with oxygen still further 

 serve to establish that conclusion. It appears that four volumes 

 and. a half of oxygen are required for the complete combustion 

 of ot^e volume of the new compound, and that the gaseous pro- 

 duct is three volumes of carbonic acid. For the saturation of 

 one volume of olefiant gas, three volumes only of oxygen are 



