of certain iiiflamviuhle gaseous Compounds. 205 



oxide and hydrogen, may be analysed by detonation with oxygen 

 in excess ; the measure of carbonic acid formed being the equi- 

 valent of that of the original carbonic oxide. 



This proceeding depends upon the non-formation of chloro- 

 carbonic acid in a mixture of carbonic oxide and chlorine in the 

 contact cf water, and cut of the direct agency of the solar ravs. 

 Such mixture I have kept several days, occasionally renewing the 

 chlorine as it became absorbed by the water, and have not ob- 

 served any diminution in the bulk of the carbonic oxide. In all 

 these cases it is necessary to ascertain the purity of the chlorine 

 by its absorption by water, and to be aware of the evolution of 

 common air from water during that process. 



7. I repeated many of the above experiments, substituting for 

 coal gas a mixture of six volumes of hydrogen with five of ole- 

 fiant gas. The specific gravity of this mixture was ,4700 ; 

 one hundred cubical inches weighing 14,2 grains. The flame 

 with which this mixture burned was of the same colour and in- 

 tensity as that of common coal gas; its dilatation by heat was 

 similar, and it underwent an analogous increase of bulk when 

 heated with sulphur. 



The readiness with which carburetted hydrogen is decomposed, 

 when passed through red hot tubes, appears to me to offer a 

 solid objection to a mode of purifying coal gas, which has been 

 proposed by Mr. G. H. Palmer*, since it would deposit carbon, 

 and consequently sustain great loss in illuminating power. The 

 object in view was probably to get rid of the sulphuretted hydro- 

 gen ; but neither is this so to be attained. In examining coal 

 gas, I have often been struck with the formation of sulphurous 

 acid during Its combustion ; though when passed through solu- 

 tion of acetate of lead, it occasioned no blackening, a circum- 

 stance which led me to suspect the presence of some other sul- 

 phureous compound ; and I have often thought, in passing the 

 open gas pii)e.s in the streets, that I perceived the smell of sul- 

 phuret of carbon. When sulphurous acid or sulphuretted hydro- 

 gen are passed with carburetted hydrogen through a red hot tube, 

 a portion of carburet of sulphur is always formed, and the vapour 

 of that highly volatile compound may well exist in the gas em- 

 ployed for illumination, which is always hurried through the con- 

 densers and gasometer. 



8. .Most of the above experiments were now repeated upon 

 the gas obtained by liie decomposition of whale oil; its specific 

 gravity was ,7G!iO; so that 100 cubical inches weighed rather 

 more than 2.'{ grains. Deducing the composition of this gas, 

 considered as a mixture of liydrogen and oleliant, from its spe- 

 cific gravity, we should conclude that it is composed of 1 volume 



' I'cckslon on the Theorv and Piuctice of Gas-li.^hling, p. Jl.i. 



of 



