1826.] 6f Carbon and Hydrogen, S^c. 101 



It is evident that the vapour observed by Mr. Dalton and Dr. 

 Henry must have contained not only this compound, and a por- 

 tion of the bi-carburet 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 consider- 

 able 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 one volume of the vapoiu'of any of the products 

 of the oil gas Hquor 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 defiant gas is present, additional care is required in 

 analytical experiments, in consequence of the gradual combina- 

 tion of the defiant gas with the sulphuric acid. I found that 

 one volume of sulphuric acid in abundance of defiant gas, 

 absorbed about seven volumes in 24 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 



ing in its properties ; yet when analysed, it yielded the same elements in the same pro- 

 portions (Ann. de Chiniie, xx. 2-15, xxii. J 72). 



Again. ftOi. Liebig and Gay Lussac, after an elaborate and beautiful investigation 

 ot the nature of fulmmatmg compounds of silver, mercury, &c. were led to the conclusion 

 that they were salts, contaming a new acid, and owed their explosive powers to the faci- 

 lity with which the elements of this acid separated from each other (Annales de Chimie, 

 xxiy. 294, XXV. 285). The acid itself being composed of one proportional of oxy<ren, ote 

 ot nitrogen, and two of carbon, is equivalent to a proportional of oxygen + a proportional 

 Ot cyanogen, and is therefore considered as a true cyanic acid. But M. Wohler, by defla- 

 grating together a mixture of ferro-prussiate of potash and nitre, has formed a salt, wliich 

 according to his analysis, is a true cyanate of potash. The acid consists of one proporl 

 tion ot oxygen, one of nitrogen, and two of carbon. It may be transferred to various 

 other bases, as the earths, the oxides of lead, silver, &c. ; but tlic salts formed have 

 nothing m common with the similar salts of ]\IM. Liebig and Gay Lussac, except their 

 composition (Gilbert's Annalen, Ixxiii. 157 ; Ann. de C;himic, xxvii. 190). M. Gay 

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

 by admitting a different modeoftombinfttion. 



