166 Experimenls on the Gas from Coal. 



The little effect of the lime liquor on the olefiant gas, which 

 I had not anticipated, admits however of ijeing satisfactorily ex- 

 plained on known principles. Water and similar fluids absorb, 

 according to Da4ton, about |th, according to Saussure about 

 ith, of their volume of olefiant gas. The utmost quantity, there- 

 fore, which a cubic foot of lime liquor, acting upon pure olefiant 

 gas, could absorb, would be J-th of a cubic foot. But agreeably 

 to a law discovered by .Mr. Dalton, and explained and confirmed 

 by mv own experiments''', a cubic foot of lime liquor, when 

 brought into contact with 36 cubic feet of olefiant gas mixed with 

 164 cubic feet of other gases, can absorb only about one-fifth of 

 one-seventh, or -jyth, of a cubic foot of olefiant gas. This cjuan- 

 tity, which does not exceed -^-'inrth part of the olefiant gas pre- 

 sent in 200 cubic feet of the best coal gas, is too trifling a loss 

 to be discoverable by experiment, or to be worthy of being re- 

 garded in practice, even when doubled by a second washing. It 

 is therefore consistent with general reasoning, as well as with ex- 

 periment, that the washing of coal gas with a due proportion of 

 lime liquor should entirely remove the sulphuretted hydrogen gas 

 and other offensive ingredients, without abstracting an appreci- 

 able quantity of either of the carburetted hydrogen gases. It is 

 nevertheless important that the quantity of water, employed in 

 washing the gas, should not be increased beyond what is neces- 

 sary to give the mixture due fluidity, because, under equal cir- 

 cumstances, the power of water to absorb a gas is in direct pro- 

 portion to the quantity employed. 



Such are the principal circumstances that occurred to me as 

 requiring to be investigated, and to be at the same time capable 

 of affording results that may admit of general application where- 

 ever coal gas is employed as a source of light. There are others 

 of more limited utility, that may be left to be determined by those 

 persons who are interested respecting them ; such as the pre- 

 ference due to different varieties of coal as sources of gas, and 

 sometimes even to other inflammable substances, which, on ac- 

 count of local situation, may be entitled to preference over coal. 

 The facts which have been stated supply, also, data for deciding 

 other questions, which may be suggested by circumstances of 

 partial interest ; — for example, whether it may not be adviseable, 

 in some cases, to collect only the first portions of gas ; or, if all 

 be collected, to reserve diflferent portions apart from each other, 

 and to apply them to appropriate uses. Thus, when coal gas is 

 conveyed in portable gasometers to a distance, (as is now prac- 

 tised by Mr. Lee in supplying his house two miles from the ma- 



* Nicholson's Journal, 8vo. vii. 2!)7- and Thomson's Annals, vii. 214. 



nufactory,) 



