which are evolved in Coal-Mines. 147 



so that the gas is forced to pass through the seams, it burns with 

 almost as yellow a flame as defiant gas. It is only below that 

 the flame is somewhat blue. When, in order to collect the 

 gas, I introduced a funnel into the pumping-pipe, and luted it 

 all round, so that it was necessary for the gas to issue through 

 the narrow opening, it burnt with a 'flame which was two feet 

 high, and which was only blue under from one to two inches, 

 but otherwise was entirely of a light yellow tint. By prevent- 

 ing the exit of the water to the side, it was obliged to force it- 

 self through the narrow opening of the funnel, and there was 

 then formed a fountain composed of water and gas more than 

 two feet high. The water formed the middle of the fountain* 

 and the gas surrounded it like a mantle. It presented a beau- 

 tiful spectacle when the gas was lighted, and the flame played 

 round the cylinder of water. This flame was also yellow, and 

 only somewhat blue below. If the pumping-pipe was so closed 

 that the gas was forced to issue rapidly along with watery va- 

 pour through a glass tube about two lines in diameter, the gas 

 burned with a pure blue flame. 



Hence we perceive that the colour of the flame of an in- 

 flammable pit-gas can vary very much according to the mode 

 of its issuing forth, and even according to the greater or smaller 

 quantity of atmospheric air with which it comes in contact. 

 Hence, by means of this colour, we can hardly form a con- 

 clusion respecting the chemical constitution of the gas. 



The gas is evolved with force. 



The chemical examination afforded the following results : — ■ 



1. The gas troubled like water. In the various experi- 

 ments, therefore, a gas was employed which had been washed 

 with a solution of potash. 



2. Chlorine gas, added to the gas in a flask of black, opaque 

 gla»s. absorbed 0.0656 of its volume. 



3. The gas contained no carbonic oxide gas. 



4. It likewise contains no vapours which are absorbable by 

 sulphuric aci'l. 



5. According to four analyses in the eudiometer, which 

 agree very nearly with one another, I have found that one vo- 

 lume of this gas, with four volumes of oxygen, affords, by the 



