VOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 221 



XVII 1. Experiments on Carbonated Hydrogenous Gas; with a Flew to determine 

 whether Carbon be a Simple or a Compound Substance. By Mr. fVm. Henry, 

 p. 401. 



The progress of chemical science depends not only on the acquisition of new 

 facts, but on the accurate establishment, and just valuation, of those we already 

 possess: for its general principles will otherwise be liable to frequent subversions; 

 and the mutability of its doctrines will but ill accord with the unvaried order of 

 nature. Impressed with this conviction, I have been induced to examine 

 a late attempt to withdraw from its rank among the elementary bodies, one 

 of the most interesting objects of chemistry. The inferences respecting the com- 

 position of charcoal, deduced by Dr. Austin from his experiments on the heavy 

 inflammable air, (Philos. Trans., vol. 80), lead to changes so numerous in our 

 explanations of natural phenomena, that they ought not to be admitted without 

 the strictest scrutiny of the reasoning of this philosopher, and an attentive repeti- 

 tion of the experiments themselves. In the former, sources of fallacy may I think, 

 be easily detected; and in the latter, there is reason to suspect that Dr. Austin has 

 been misled by inattention to some collateral circumstances. Several chemists 

 however, of distinguished rank, have expressed themselves satisfied with the evi- 

 dence thus produced in favour of the composition of charcoal; and among these 

 it may be sufficient to mention Dr. Eeddoes, who has availed himself of the 

 theory of Dr. Austin, in explaining some appearances that attend the conversion of 

 cast into malleable iron. Philos. Trans., vol. 81. 



The heavy inflammable air, having been proved to consist of a solution of pure 

 charcoal in light inflammable air, is termed, in the new nomenclature, carbonated 

 hydrogenous gas. By repeatedly passing the electric shock through a small quan- 

 tity of this gas, confined in a bent tube over mercury, Dr. Austin found that it 

 was permanently dilated to more than twice its original volume. An expansion so 

 remarkable could not, as he observes, be occasioned by any other known cause 

 than the evolution of light inflammable air. When the electrified air was fired 

 with oxygenous gas, it was found that more oxygen was required for its saturation 

 than before the action of the electric fluid ; which proves that, by this process an 

 actual addition was made of combustible matter. The light inflammable air dis- 

 engaged by the electrization, doubtless proceeded from the decomposition of some 

 substance within the influence of the electric fluid, and not merely from the ex- 

 pansion of that contained in the carbonated hydrogenous gas; for had the quantity 

 of hydrogen remained unaltered, and its state of dilatation only been changed, 

 there would not, after electrization, have been any increased consumption of 

 oxygen. 



The only substances in contact with the glass tube and mercury, in these expe- 

 riments, besides the hydrogen of the dense inflammable gas, were carbon and 

 water; which last, though probably not a constituent of gases, is however co- 



