34 Lh-. Henry's Experiments on the Gas from Coal. [Jan. 



quantity, therefore, which a cubic foot of hme liquor, acting 

 v\pon pure defiant gas, could absorb, would be one-seventh of a 

 cubic foot. But agreeably to a law discovered by Mr. Dalton, 

 and explained and confirmed by my 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 -^i\\ of a cubic 

 foot of olefiant gas. This quantity, which does not exceed 

 __i_^th part of the olefiant gas present in 200 cubic feet of the 

 best coal gas, is too trifling a loss to be discoverable by experi- 

 ment, or to be worthy of being regarded in practice, even when 

 doubled by a second washing. It is, therefore, consistent with 

 oeneral reasoning, as well as with experiment, that the washing 

 of coal gas with a due proportion of lime liquor should entirely 

 remove the sulphuretted hydrogen gas and other offensive ingTe- 

 dients, without abstracting an appreciable 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 necessary to give the mixture 

 due fluidity, because, under equal circumstances, the power of 

 water to absorb a gas is in dn-ect proportion 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 hmited utility that may be left to be determined by those 

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

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

 sometimes even to other inflammable substances, which, on 

 account of local situation, may be entitled to preference over 

 coal. The facts which have been stated supply also data for 

 deciding other questions, Avhich may be suggested by circum- 

 stances 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 difterent portions apart 

 from each other, and to apply them to appropriate uses. Thus, 

 when coal jias is conveyed in portable oasometers to a distance 

 (as is now practised by Mr. Lee in supplying his house two miles 

 from the manufactoryt), it will be important to select that gas, 

 v.'hich in a given volume has the highest illuminating power, and 

 which, therefore, requires vessels of the smallest capacity for its 



♦ NicliolsoR's Jduni.il, Svo. Tii. 297, and Tho^r.son's^innaJs, »ii. 214. 



+ A small carringe upon springs conveys two square dote {gasometers made of 

 'n'roi>s:lit inui plaiet-, and eacli coiitainiiiE; 50 cu'.iic feet of pciiectly pnrificJ gas, 

 equivalent l(i,^etlier lo ahotit 6 lljs. of taliow. Eacl) gasometer weighs about 

 160 lbs. anil i:as a vulve at the bottom, which is opeced by t!ie upright main pip<*. 

 Ihe moment the gasometer is immersed in the pit. The strength of one man is found 

 fo be sufficient for the labour of removing the ga;i)mcter from the carriage to it* 

 j)lace. 



