176 Dr. Henry on tlie Aeriform Compounds [Sept. 



retted hydrogen. Mr. Dalton has since favoured me with a 

 specimen of oil gas prepared by himself, which contained in 100 

 parts, 40 of a gas condensible by chlorine ; and it appears from 

 the table that oil gas, manufactured on the large scale, may 

 contain in 100 parts, 38 parts of a gas similarly characterized.* 

 It is not improbable indeed that by a temperature carefully 

 regulated, the whole of the aeriform fluids may be obtained from 

 oil, of such quality as to be entirely condensible by chlorine ; 

 and from the great superiority of the light which such a gas 

 would afford, and the reduction that might be effected in the 

 capacity of the gasometers, the discovery of a mode of produc- 

 ing it in this state, would be an important practical improve- 

 ment. 



The inferences respecting the nature of the gas from oil, I 

 reserve till after the account of the experiments on coal gas, as 

 the same remarks, with some slight modifications, will apply to 

 both cases. 



Experiments on the Gas from Coal. 



The numerous experiments and observations on the gas from 

 coal, which I have already published, appear to me to preclude 

 the necessity of going much into the subject on this occasion. 

 What I have lately had in view, has been to render the analysis 

 of this gas more complete, by a careful examination of that por- 

 tion of it which remains after the action of chlorine. The gas, 

 submitted to these recent experiments, was prepared from Wigan 

 cannel, at the manufactory of Messrs. Philips and Lee. It was 

 collected from an opening in a pipe between the retort and the 

 tar-pit, generally about an hour after the commencement of the 

 distillation, except in the instance of the gas No. 4, which was 

 taken five hours, and No. 5, which was taken 10 hours from 

 that period. Before using it, the carbonic acid and sulphuretted 

 hydrogen, which were always present in the early products, 

 were separated by careful ablution with liquid potash. As the 

 gas No. 5, was not at all diminished by chlorine, it was 

 obviously unnecessary to examine it in any but its entire state. 



" Since this paper was written, I have received from Mr. Phillips a second specimen 

 of oil gas prepared by Messrs. Taylor. It contains in every 100 volumes, 42 or 43 

 parts of gas condensible by chlorine; but in other respects very nearly agrees (making 

 allowance for the greater proportion of that ingredient) with die gas described in the 

 text. 



