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XIII. On the aeriform compounds of Charcoal and Hydrogen ; 
with an account of some additional experime?its on the gases 
from oil and from coal. By William Henry, M. D. 
F. R. S. &c. 
Read February 22, 1821. 
.The experiments on the aeriform compounds of charcoal 
and hydrogen, described in the following pages, are supple- 
mentary to a Memoir on the same class of bodies, which the 
Royal Society did me the honour to insert in their Trans- 
actions for 1808, as well as to other papers on the same 
subject, which have been published in Mr. Nicholson's Jour- 
nal, and in the Memoirs of the Manchester Society. Of these 
essays, I beg leave to offer a very brief recapitulation, with 
the view merely of connecting them with what is to follow. 
In the first of these essays (Nicholson's Journal, 8vo. June, 
1805), I detailed a series of experiments on the gases ob- 
tained by the destructive distillation of wood, peat, pit-coal, 
oil, wax, &c. from which it appeared that the fitness of 
those gases for artificial illumination was greater, as they 
required for combustion a greater proportional volume of 
oxygen ; and that the gases generated from different in- 
flammable bodies, or from the same inflammable substance 
under different circumstances, are not so many distinct spe- 
cies, which under such a view of the subject would be almost 
infinite in number, but are mixtures of a few well known 
gases, chiefly of carburetted hydrogen with variable pro- 
