246 - Expert mtHis m carlanatetH Ujdrogtn Gat. 



able, if the gas had been farther expanded before the admifRon of the liquid. The change itt 

 the lime water was very trifling \ but my friend Mr. Rupp, who witnefTcd this as well as 

 feveral of the other experiments, and who is much converfant in the obfervation of chemical 

 facls, was fatisfied that after a while he faw fmall flocculi of a precipitate on the furface of 

 the mercury. This contra£lion of bulk cannot be afcribed to any other caufe than the ab- 

 forption of carbonic acid ; for, befides the fa£l, that the colour of fyrup of violets and of 

 turmeric, which I aifo tried, were not affeited by expofure to the electrified gas, I have this' 

 obje£lion to the abforbed gas being ammoniac, that no diminution either of bulk or tranf- 

 parency occurred on the admixture of muriatic acid gas with the eleGrifled air; whereas 

 ammoniac would have been exhibited under the form of a neutral fait. When water was 

 pafied up to this mixture of the two gafes, there was an abforption not only of the muriatic 

 gas but of fomething more. 



Conceiving that the demolition of charcoal, by the a£lion of the eleftric fluid, was fuffi- 

 ciently proved by his experiments, Dr. Auftin afllgns the evolved hydrogen as one of its 

 conrtitueius, and the other he concludes to be azote. This inference, however, refts almoft 

 entirely upon eftimates in which material errors may be difcovered. Some of thefe it may 

 be well to point out for the fatisfadtion of fuch as have acquiefced in Dr. Auftin's opinion. 



The carbonated hydrogenous gas fubmitted to Dr. Auftin's experiments, clearly appears 

 from his own account to have been largely adulterated with azotic gas. One fource of its 

 impurity he has difclofed, by informing us that the gas " had been very long expofed to 

 water* ;" for Dr. Higgins has fomewhere fhewn, that the heavy inflammable air, after land- 

 ing long over water, leaves a larger refidue of azote, on combuftion, than when recently pre- 

 pared f . It is probable alfo, that the proportion of azote derived from the water would in- 

 creafe with the time of its expofure ; and thus a fertile fource of error is fuggefted, which 

 appears wholly to have efcaped Dr. Auftin's attention. In repeating his experiments, I was 

 careful that comparative ones, on two equal quantities of the electrified and uneledtrified gas, 

 {hould be made without the intervention of any time that could vary the proportion of azote 

 in either of the gafes. 



To the 9th experiment, in which the quantity of azote feems to have been increafed to 

 eleflrization, I muft repeat the objection, that a fufiiciency of oxygenous gas was not ufed iij 

 the combuftion. In the 8th experiment, 2,83 meafures of the uneledtrified air were fired with 

 4,17 oxygenous gas, and only 0,15 of the latter remained above what was fufficient for fatura- 

 tion ; but in the 9th, though the 2,83 meafures were expanded to 5,16, the quantity of 

 oxygen employed was 0,08 lefs than in the former experiment ; and it may therefore be 

 prefumed, that a fmall quantity of inflammable air might efcape unaltered, and might add 

 apparently to the product of azote. In the 8th experiment, alfo, the portion of oxygenous 

 gas that was more than fufficient to faturate the carbonated hydrogen, would probably com- 

 bine in part with the remaining azote, as in the experiments of Dr. Higgins J and Dr. 

 Prieftley §. But in the ytb, the quantity of oxygenous gas was hardly fufficient to faturate 



• Phil. Tranf. Ixxx. 54. 



>{■ Similar fafls refpefting the deterioration of other gafes by (landing over water may be feen in Dr. 

 Prieftlcy's Experiments on Air, vol. i. p. 59. 158. I found that oxygenous gas from oxygenated muriate of 

 pot-alh acquired by expofure a few weeks to water, ,125 its bulk of azotic gas. 



J Experiments and Obfervations on Acetous Add, fcc. p. 295. 



§ Phil. Tranf. Ixxix. 7, 



6 both 



