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XX. — On the Analysis of Gaseous Mixtures. By JoHN 

 Leigh, Esq., M.R.C.S., F.C.S. 



Head January 7, 1851. 



The chief object of this paper is an examination of the 

 methods hitherto employed for determining the constitu- 

 ents of coal gas. Of late, considerable attention has been 

 given by chemists to the products of the distillation of coal, 

 as well as to those of its combustion, and of its spontaneous 

 decomposition; and it is likely that their researches will 

 erelong come to have a high value, and will throw much 

 light on the great process of gas manufacture, on the eco- 

 nomical employment of fuel as an agent in the production 

 of steam, and in the great smelting operations of this coun- 

 try ; and also in explanation of the production of the fire- 

 damp, whose disastrous explosions so often occupy public 

 attention. 



I shall confine myself to an examination of the methods 

 employed, analytical or otherwise, for determining the com- 

 position or the illuminating power of the gases resulting 

 from the distillation of coal. There are few gaseous mix- 

 tures that have offered more difficulties to the chemist than 

 those which make up the composition of coal gas ; and as 

 the time has now arrived, when a correct mode has become 

 eminently desirable of ascertaining the proportions and 

 constitution of the light-giving ingredients contained in the 

 mixture, so that it may serve as a measure of the relative 

 illuminating power of the gas, I will give a description of the 

 method which I have been in the habit, for several years past, 

 of employing in the examination of the gas produced at the 

 Manchester gas-works. 



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