IG On Sir H. Davy's Theory of [July, 



the estimate of Kinvan,* nearly 144 '04 cubic inches, and 100 

 grs. of oxymuriatic gas, as appears from Mr. Dalton's experi- 

 ments^ are equal to 137'9 inches, which, being reduced, give 

 a proportional bulk, as 100 of hydrogen to 95*7 of oxymu- 

 riatic gas. Thus we see that Mr. Dalton's experiments agree 

 almost exactly with the result of calculation ; and if the 

 hydrogen he employed was contaminated by the slighest 

 admixture of extraneous matter, the quantity of oxymuriatic 

 gas condensed by it must of course have been proportionally 

 lessened. 



Mr. Dalton, having denied the existence of aqueous vapour 

 in muriatic acid gas, ascribes the appearance of hydrogen during 

 the action of certain bodies on that gas to the decomposition of 

 the acid, which he looks on as a quaternate compound of oxygen 

 and hydrogen. While, however, he admits the fact as stated by 

 Sir H. Daw, % that " when potassium was heated in muriatic 

 acid gas as dry as it could be obtained by common chemical 

 means, the gas wholly disappeared, and from one-third to one- 

 fourth of its volume of hydrogen was evolved, and muriate of 

 potash was formed." He questions the accuracy of an experi- 

 ment detailed in the Bakerian lecture for 1809, by which this 

 conclusion was established, in this experiment it was found that 

 8 grs. of potassium absorbed 22 cubic inches of muriatic acid 

 gas, and gave out 8 inches of hydrogen. 



Before proceeding to examine Mr, Dalton's reasoning on this 

 experiment, it may be well to take a view of it, unconnected 

 with his speculations on the nature of muriatic acid. 



According to the analysis of Sir H. Davy,§ 8 grs. of 

 jpotassium may be converted into potash, by union with about 

 1*29 152 gr. of oxygen. In order to furnish this oxygen, if 

 water be its source, W95954 gr. of that fluid must suffer 

 decomposition ; and this quantity is sufficient, at the rate of 25 

 per cent, to give the gaseous form to 5"983736 grs. or in the 

 proportion of 26-2G479 to S^JISO grs. only of muriatic acid 

 gas. At the same time that the oxygen of this water is absorbed 

 by the potassium, its hydrogen, amounting to '204414 of a gr. 

 or 7*82297 inches, must be set at liberty. Thus it appears that 

 the hydrogen evolved was almost exactly equal in quantity to 

 what could be afforded by a portion of water sufficient to oxidate 

 the potassium employed. 



The experiment appears, however, to be inaccurate, with 

 regard to the absorption of the 22 inches of muriatic acid gas : 

 for 9"29L52 grs. of potash are capable of combining with the 

 real acid contained in 5-59055 grs. of muriatic acid gas, which 



* Essay on Phlogiston, p. 30. + New System, p. 297. 



f Phil. Iran?. lfeOtf, p. § Phil. Trans. 1808, p. "8. 



