YOL. LXXXVII.] PHILOSOPHICAL TRANSACTIONS. 225 



expansion, I found that it could not be carried beyond £ the original bulk, of the 

 gas. By 160 very strong explosions it attained this small degree of dilatation, but 

 80 more produced not the least effect; though the former number would have been 

 amply sufficient to have dilated the gas, in its ordinary state, to more than twice 

 its original volume. A drop or 2 of water being admitted to this portion of gas, 

 the expansion went on as usual; and I may here observe, that when a little water 

 gained admission into the tube along with the gas, in any experiment, which often 

 happened before I had acquired sufficient expertness in transferring the air from 

 water to mercury, the dilatation went on with remarkable rapidity. 



Carbonic acid gas, according to the discovery of M. Monge*, undergoes, when 

 submitted to the electric shock, a change similar to that effected on the carbonated 

 hydrogen; and the expansion has been shown, by Messrs. Landriani and Van 

 Marum-j", to be owing to the same cause, viz. the extrication of light inflammable 

 air. The added gas, M. Monge ably contends, cannot proceed from any other 

 source than the water held in solution by all aeriform bodies, the oxygen of which 

 he supposes to combine with the mercury. That the decomponent of the water 

 however, in the experiments which I have described, is not a metallic body, will 

 appear highly probable when we reflect that there is present in them a combustible 

 substance, viz. charcoal, which attracts oxygen much more strongly than metals; 

 and the following experiments evince that the mercury, by which the air was con- 

 fined, had no share in producing the phenomena. 



Exper. Q. A portion of carbonated hydrogenous gas was introduced in a glass 

 tube closed at one end, into which a piece of gold wire was inserted, that projected 

 both within and without the cavity of the tube. The open end of the tube was 

 then closed by a stopper perforated also with gold wire, so that electric shocks 

 could be passed through the confined air, without the contact of any metal that has 

 the power of decomposing water. On opening the tube with its mouth downwards, 

 under water, a quantity of air immediately rushed out. — Exper. 10. The dilatation 

 of the gas was found to proceed very rapidly when standing over water, and exposed 

 to the action of the electric fluid, conveyed by gold conductors. 



We have only therefore, in the 2 preceding experiments, one substance into con- 

 tact with the gas which is capable of decomposing water, viz. charcoal. The union 

 of this body with the oxygen of the water would be rendered palpable by the for- 

 mation of carbonic acid ; but Dr. Austin did not observe that any precipitation was 

 occasioned in lime-water, by agitating it with the electrified gas. On passing up 

 syrup of violets to the electrified air, with the expectation of its indicating the vola- 

 tile alkali, as in the experiments of Dr. Austin, no change of colour took place, 

 though the test was of unexceptionable purity. On examining however, whether 

 any alteration of bulk had been produced in the air by the contact of this liquid, it 

 appeared, that of 700 measures, 100 had been absorbed. Suspecting that the ab- 

 sorption was owing to the presence of carbonic acid, I introduced some lime-water 



* 29 Journal de Physique, 277- — f 2 Annales de Chimie, 273. — Orig. 

 VOL. XVIII. • G G 



