255 Description of an Apparatus for the 



tain an approximation, at least to the proportions in which 

 carbonic acid, defiant, and suiphureted hydrogen gas are 

 mingled with the aeriform product of coal. The rule may 

 be stated as follows : To a measured quantity of oxy-muria- 

 4ic acid gas, contained in a graduated tube, add twice Us 

 bulk of the recent coal gas, and at the expiration of one or 

 two minutes observe the diminution which has taken place. 

 Wash an equal quantity with caustic potash ; note the loss ; 

 and submit the residue to the action of oxy-muriatie acid 

 as before. The second diminution, thus effected by oxy- 

 muriatic gas, divided by 2*2,- gives the proportion of ole- 

 fiant gas. Deduct this absorption from the first, and, di- 

 viding the remainder by 1*8, we obtain the quantity of sul- 

 phuretcd hydrogen. Lastly, to know the quantity of car- 

 bonic acid gas, subtract, from the diminution effected by 

 potash, the amount of the sulphurated hydrogen gas. An ex- 

 ample, taken from actual experiment, will best explain the 

 application of this rule. 



One hundred measures of the first product of gas from 

 cannel coal lost, by agitation with liquid potash, 9' 7 

 measures. The remainder, being mingled with one fourth 

 its bulk of oxy-muriatic acid gas, the mixture lost 10*4 

 measures. This diminution, 10*4, divided by 2*2, gives 

 4* 9 for the proportion of olefiant gas. But 100 measures of 

 the unwashed gas sustained, by admixture with oxy-muria- 

 tic acid, a diminution of 20 measures. Now, deducting, 

 from this diminution, that occasioned by the condensation 

 of olefiant gas, (viz. 20— 10*4,) there remain 9*6, which, 

 divided by 1*S, gives 5*3 for the proportion of sulphureted 

 hydrogen gas. And the diminution by potash (= 9-7) — , 

 5*3 gives 4*4 for the proportion of carbonic acid gas. Hence 

 100 measures of the first product of gas from cannel coal 

 contain, 



1 . Of inflammable gas, not affected by thel 

 foregoing agents J 8 4 



2. Of sulphureted hydrogen gas - - 5*3 



3. Of olefiant gas - - - . 4*9 



4. Of carbonic acid gas - - . 4«4 



100 



The 



