170 On some new Products [1825. 



Dr. Henry must have contained not only this compound, and a 

 portion of the bicarburet of hydrogen, but also portions of the 

 other (as yet apparently indefinite) substances ; and there can 

 be no doubt that the quantity of these vapours will vary from 

 the point of full saturation of the gas, when standing over 

 water and oil, to unknown, but much smaller proportions. It 

 is therefore an object in the analysis of oil and coal-gas, to 

 possess means by which their presence and quantity may be 

 ascertained; and this I find may be done with considerable 

 exactness by the use of sulphuric acid, oil, &c., in consequence 

 of their solvent power over them. 



Sulphuric acid is in this respect a very excellent agent. It 

 acts upon all these substances instantly, evolving no sulphurous 

 acid ; and though when the quantity of substance is considerable 

 as compared with the acid, a body is left undecomposed by or 

 uncombined with the acid, and volatile, so as constantly to 

 afford a certain portion of vapour, yet when the original sub- 

 stance is in small quantity, as where it exists in vapour in 

 a given volume of gas, this does not interfere, in consequence 

 of the solubility of the vapour of the new compound produced 

 by the action of the acid in the acid itself in small quantities : 

 and I found that when 1 volume of the vapour of any of the 

 products of the oil-gas liquor was acted upon, either alone, or 

 mixed with 1, 2, 3, 4, up to 12 volumes of air, oxygen, or 

 hydrogen, by from half a volume to a volume of sulphuric acid, 

 it was entirely absorbed and removed. 



When olefiant gas is present, additional care is required in 

 analytical experiments, in consequence of the gradual combi- 

 nation of the olefiant gas with the sulphuric acid. I found 

 that 1 volume of sulphuric acid in abundance of olefiant gas, 

 absorbed about 7 volumes in twenty-four hours in the dull 

 light of a room; sunshine seemed to increase the action a 

 little. When the olefiant gas was diluted with air or hydrogen, 

 the quantity absorbed in a given time was much diminished ; 

 and in those cases it was hardly appreciable in two hours, 



the similar salts of MM. Liebig and Gay-Lussac, except their composition 

 (Gilbert's Annalen, Ixxviii. 157; Ann. de Chimie, xxvii. 190). M. Gay-Lussac 

 observes, that if the analysis be correct, the difference can only be accounted 

 for by admitting a different mode of combination. 



