314 Dr Bischof s Examination of Three Inflammable Gases 



was filled with gas. I took advantage of the favourable op- 

 portunity, and filled a hundred bottles, and in the same man- 

 ner transported them to Bonn, well closed, and secured by 

 water. 



It thus appears that the difference between this stream of 

 gas and that of Gerhard's Stollen is, that the former issues 

 with a pressure which is somewhat greater than that of the at- 

 mospheric air, while the pressure of the latter is just equal 

 to that of the atmosphere. This difference can be easily 

 explained. While the gas from the Wellesweiler mine is 

 evolved from the floor covered with water, all the fissures 

 which descend from this level, and which communicate with 

 the above-mentioned principal fissure, must be filled with 

 water. Hence, all the gas which ascends from beneath is 

 hemmed in by water. This chief fissure, which is probably 

 variously ramified beneath with other gas canals, presents the 

 smallest amount of hindrance to the evolution of the gas, be- 

 cause, in a wide fissure, gas and water can be more easily se- 

 parated than in a narrow one. Hence, the gas is evolved from 

 this fissure only, and the remaining narrower canals are in- 

 terrupted by water. In Gerhard'' s Stollen, on the contrary, 

 the current of gas is evolved about 7 feet above the floor of 

 the mine. Hence, also, when up to that floor, all the gas ca- 

 nals are filled with water, this can cause no hindrance, inas- 

 much as the fissure is probably continued to the surface and 

 is ramified.* An interruption, therefore, which meets the cur- 

 rent of gas flowing outwards, will cause it to remove to ano- 

 tlier place. It is possible that, during continued wet weather, 

 where the fissures communicating with the surface are ob- 

 structed by water, the gas exerts a pressure superior to that 

 of the atmospheric air. Such relations, at least, are presented 

 by the exhalations of carbonic acid gas, of which several exam- 

 ples are known to me in the neighbourhood of the Laacher 

 S^e, and of the volcanic Eifel, both of which districts are so 

 rich in very large gaseous evolutions, 



* This suppositibn has been completely confirmed. An officer of the mine 

 informs me, that the blower has ceased to flow in ; doubtless because a stra- 

 torn of coal has lately been, worked 28 feet above the said blower. 



