174 Dr. Henri/ on the A'erifqrm Compounds [Sept. 



the water appeared. The diminution of volume thus ascer- 

 tained, divided by 2, was found to give pretty correctly the 

 quantity of olefiant gas known to be contained in the mixture. 

 But the greatest precision was attained by waiting 15 or 20 

 minutes, and then quickly washing the remaining gas with 

 dilute solution of potash, in order to remove the excess of chlo- 

 rine. From the volume of the residuary gas, it was necessary 

 to deduct the amount of impurity previously ascertained to exist 

 in the chlorine ; and the remainder, taken from the volume of 

 mixed gases which had been operated on, showed how much 

 olefiant gas had been condensed by the chlorine. When very 

 narrow tubes were employed, and the column of gases mixed 

 with chlorine was of considerable length, a longer continuance 

 of the experiment was found necessary, and the gases were 

 suffered to remain in contact during an hour or more. In this 

 way it was ascertained, that, olefiant gas may be accurately 

 separated by chlorine from hydrogen, carburetted hydrogen, or 

 carbonic oxide gases, or from mixtures of two or more of those 

 gases, which are left quite unchanged in volume and in chemical 

 properties, when light has been carefully excluded from the 

 mixture. 



This property of chlorine is the foundation of a fresh analysis, 

 to which 1 have thought it expedient to submit the gases from 

 coal and ojl, in order to decide what aeriform fluids remain after 

 the separation of that portion which is condensible by chlorine; 

 — whether the residue consists, as I have heretofore maintained, 

 of carburetted hydrogen chiefly, with variable proportions of 

 hydrogen and carbonic oxide ; or whether, according to the 

 new view of the subject, it consists of hydrogen gas only. 



In the experiments made for this purpose, I operated gene- 

 rally on from 60 to 80 cubic inches of oil gas or coal gas, assay- 

 ing a small specimen first, as a guide to the quantity of chlorine 

 which it would be necessary to employ. The volume of chlorine 

 thus found to be requisite, and about half as much more, was 

 passed into an air receiver standing over water, and completely 

 shaded by an opaque cover which was fitted over it. The oil or 

 coal °as was then added by degrees, if much condensation was 

 expected, because in that case a considerable increase of tem- 

 perature would have been produced by the sudden admixture of 

 large quantities ; or at once, if only a moderate action had been 

 indicated by the previous assay. The mixture was allowed to 

 stand, completely guarded from the light, during 30 or 40 

 minutes, or even longer, and the residue was expeditiously 

 washed with liquid potash, and a small portion again assayed, 

 to ascertain that the action of the chlorine was complete. The 

 specific gravity of the washed gas was then carefully taken, that 

 of the entire gas having been previously determined: and the 

 results of its combustion with oxygen examined, and compared 

 with those of the gas in its original state. 



