304 Koyal Snciety. 



those views of the compounds of charcoal and hydrogen wliich 

 had arisen out of his former experiments, and those of Mr. Dal- 

 ton, were correct ; especi;illv whether there be a compound an- 

 swering in its characters to light carbureftcd hydrogen gas, the 

 existence of which had been called in question in a late Bake- 

 rian lecture. This, after attentively, and at various times, ex- 

 amining the gas from stagnant water, he pronounces to be a di- 

 stinct chemical compound, having uniformly the same composi-- 

 tion and chemical properties, and the same specific gravity 

 (0'55ti). It is constituted of 100 parts by weight of charcoal 

 united with 33*40 of hydrogen ; while defiant gas consists of 

 100 charcoal + 16*70 hydrogen. Hence, if the latter be consi- 

 dered as a compound of one atom of charcoal and one atom of 

 hydrogen, carburetted hydrogen must consist of one atom of 

 charcoal and two atoms of hydrogen; and as 100 cubic inches 

 of carburetted hydrogen contain hydrogen equivalent to 200 cu- 

 bic inches of hydrogen gas, he suggests the verification of the 

 specific gravity of hydrogen gas by that of carburetted hydrogen, 

 and finds that in this way it comes out 0'0()98, making the re- 

 lative weights of the atoms of hydrogen and oxygen very nearly 

 as 1 to 8. The atom of charcoal also he estimates from the 

 composition of carburetted hydrogen, and of carbonic acid, at 0. 



His next experiments relate to the best means of analysing 

 mixtures of olefiant gas with hydrogen, carburetted hydrogen, 

 or carbonic oxide ; and of olefiant gas with all those three gases. 

 Chlorine, he shows, may be employed with perfect accuracy, 

 provided certain precautions are observed, which are described 

 at length in the paper. The chief of these is the complete ex- 

 clusion of light, for in that case olefiant gas alone is condensed; 

 but even the faint light of a cloudy day was found sufficient to 

 cause the speedy action of chlorine on the other gases. The 

 paper contains also directions for analysing mixtures of hydro- 

 gen, carburetted hydrogen, and carbonic oxide ; but these, from 

 their nature, are incapable of abridgment. 



By the analytical processes thus established, he proceeds to 

 examine the composition of oil gas and coal gas. The results 

 are given in tables ; but the general issue of the experiments is, 

 that oil gas (as he had formerly shown with respect to coal gas) 

 is very far from beiiig uniform in composition, but differs greatly 

 in specific gravity and combustibility, when prepared at different 

 times even from the same kind of oil, owing to variations of 

 temperature and other circumstances. Essentially the gases 

 from oil and from coal are composed of the same ingredients, 

 though in different proportions, viz. simple hydrogen, light car- 

 bufettdd hydrogen, and carbonic oxide gases, with the addition 

 of variable proportions of an elastic fluid, which agrees with ole- 

 fiant 



