On Chemical Equwale fits. 99 



shall quote a few passages, as he gives them, from his Coiitpn- 

 rative View, which I think are flecisive iji this miukuueutal dis- 

 cussion. 



" Hepatic gas (sulphuretted hydrogen), as shall l>e show», is 

 hydrogen in its fii)! extent, holding sulphur in solntJon/' This 

 facf, of hydrogen not changing its voiitnie, by coinhjning with 

 sulphur, has been marked among the vakiable discoveries of later 

 times. 



*' Therefore, 100 grains of sulphur require only 100 or !02 

 of the dry gravitating matter of oxygen gas, to forin sulphurous 

 acid. vVs sulphurous acid gas is very little more tlinn doable the 

 specific gravity of oxygen gas, we may concinde, that the ulti- 

 mate particles of sulphur and oxygen contain tlje same quantity 

 of matter; for oxvgen gas suffers no coiisideraide diminution of 

 its bulk, by uniting to the quantity of sulphur necessar)' for the 

 formation of sulphurous acid. It contracts 1-1 Ith, as shall be 

 shown hereafter." Compare with the above statements the fol- 

 lowing from Dr. Thomson's System, published in 1807. "If 

 this analysis be precise, it follows, tliat 100 cubic inches of hy- 

 drogen gas, in order to be converted into sulphuretted hvdrogen, 

 combine with 7'fJ9 grains of sulphur, and are converted into 

 about 2()'6 ciil)ic inches ; so that hydrogen gas, by dissolving 

 sulphur, is reduced to little more than one-fourth of its original 

 bulk." Vol. i. p. 92. Sir H. Davy has siaice proved, Ijy accu- 

 rate experiments, that hydrogen, in its conversion into sulphu- 

 retted hydrogen, does not eliange its bulk, agreeably to Mr. Hig- 

 gins's early enunciation. " But as we know the constituents of 

 sulphuric acid, it is easy thence to deduce the follovving'as the 

 jnoportion of the ingredients of sulphurous acid : — 



()S sulphur, 



'62 oxygen. 



100." — Sifttetti nf Chemiih;/, 1807, 

 vol. ii. p. 179. The l.ast is the result of Dr. Thomson's own 

 experiments. Its true composition is now. known to be 100 of 

 the gravitating matter of oxygen to 100 of sulphur, in conformity 

 with Mr. lliggins. 



The elementary proposition of Mr. Dalton's atomical hypo- 

 thesis, seems to be most explicitly announced in the toilowing 

 paragraph of Mr. lliggins. 



" .As two cubic inches of hydrogen gas re(|uire but one cubic 

 inch of oxygen gas to condense theni to water, we may presinne, 

 that they contain an ecjua! number of divisions, and that the dif- 

 ference of the specific gravity of those gases depends on the size 

 of their respective particles; or we mu^t sujipose, that an ulti- 

 mate particle of hydrogen refjuires two or three or more paili- 



N 2 cle. 



