Eocperiments on the Gas from Coal. 121 



are never suffered, during the whole of the winter season, to fall 

 below the temperature of ignition. The gas was collected in a 

 bladder furnished with a stop-cock, which was fixed into an open- 

 ing in the pipe between the retort and the tar-pit. It was taken 

 at this place, in order to avoid contact with water, and admix- 

 ture with any atmospherical air, that might accidentally remain 

 in the gasometer. Wishing to examine the gas in a perfectly 

 recent state, and finding it impossible to make the necessary ex- 

 periments with sufficient accuracy in a shorter interval, I was 

 obliged to be satisfied with procuring it every other hour. In this 

 place, I shall only state the general results ; and I shall describe, 

 in a subsequent part of the paper, the methods of analysis, in or- 

 der that other persons, who may choose to compare my experi- 

 ments with their own, may conduct them under equal circum- 

 stances. 



By the expression impure gas, is to be understood, the gas 

 precisely in the state in which it was collected from the retort; 

 and by pur'ijied gas, the same product after being freed from car- 

 bonic acid and sulphuretted hydrogen by solution of pure potash, 

 applied in very small c|uantity, relatively to the volume of the gas, 

 and with the least agitation adequate to the effect. 



TABLE I. 



Showing the OuaUtij of Gas from WlQlhs. of Cannel, at df- 

 ferent Periods of the Disiillaiion. 



Hours from the 100 measures of im- 

 commence- pure gas contain of 



/ 



9 

 12 



Sul.hyd. carb.ac. 



2i 

 2| 

 2i 



2 



give 

 carb. 

 acid. 



94 

 112 

 108 

 94 

 83 

 73 

 54 

 36 



Excluding from the calculation the azotic gas, with various 

 proportions of which the products were contaminated, the follow- 

 ing tabic shows the quantity of oxygen gas consumed, and of 

 carbonic acid produced, by the really combustible part of the 

 gas. 



TABLE 



