316 Dr Biscliof s Examination of Three Inflammable Gases 



If, on the contrary, the mining operations should be carried on 

 from the opposite side, proceeding from another gallery, and 

 continued from above downwards, the inflammable gas removes 

 from the working place, and the miners can without difficulty 

 perfect their work to the previously abandoned point. If the 

 strata should be very much inclined, so that the mining opera- 

 tions are carried on through such highly inclined shafts, there 

 is no fire-damp to contend with, because, in such a case, the 

 inflammable gas escapes through these shafts, immediately 

 after its evolution. 



I may be allowed to take this opportunity of communicating 

 some observations on exhalations of carbonic acid gas, which 

 present the same phenomena, but only in the opposite sense. 

 When carbonic acid gas is evolved in recesses, or in inclosed 

 spaces, which do not at all, or but slightly, partake of the ex- 

 ternal movements of the air, this heavier gas is collected, and 

 the entering such places is attended with danger to life. The 

 celebrated Grotto del cane, the gas grotto (Dunst/iohle) near 

 Pi/rmont, and several similar places in the vicinity of the 

 Laacher See, and in the volcanic Eifel, present like pheno- 

 mena. When, however, such exhalations of carbonic acid gas 

 take place in flat situations, and even in much larger quan- 

 tity, the gas becomes distributed through the atmosphere as 

 soon as it is evolved, and the rapidity of its diffusion hardly 

 admits of the presence of this mephitic gas being made known 

 by its smell. Thus, there is a spot at the village of Wehr, 

 about five English miles from the Laacher See, where car- 

 bonic acid gas is evolved in immeasurable quantity from hun- 

 dreds of mineral springs, close to one another, and wliere, at 

 many points, bubbles as large as the head scatter the water 

 to a height of more than a foot, and where, in the middle of 

 the marsh, the smell of the gas is hardly perceptible. 



Chemical Analysis of the Pit-gas from the JVellesweiler Mine. 



§ 1. Examination for Oxygen Gas. 



Nitric oxide gas mixed with the pit-gas did not produce the 

 slightest yellow colour. By adding 54 volumes of nitric oxide 

 gas to 100 volumes of pit-gas, the mixture amounted to 



