which are evolved in Coal-Mines. 



315 



consisted of a large bell-glass B, which was closed below with 



a plate luted to it P, and was 



provided with a stopcock c. A 



second stopcock b was luted to 



the bell-glass above, into which 



a hollow pipe (Hiilse) a, to which 



a leaden tube was luted, could 



be screwed. The tube t was 



luted into the fissure of the rock, 



and after the bell-glass was filled 



with water, the current of gas 



was absorbed. I found that, even 



when the cock was entirely open, 



not nearly so much water flowed 



out, orso much gas was absorbed, 



as there issued gas from the fissure. It was easy to become 



convinced of this by lighting the gas which had been again 



forced out from the cock 6, by means of insertion in a vessel 



filled with water ; for the flame was then only 2 inches high. 



As this issuing out of the gas took place in nearly the same 



time as the flowing in, while the gas coming direct from the 



fissure burned with a flame of 12 or 15 inches in height, only 



a small portion could be absorbed. I was thus well assured 



that no atmospheric air had been absorbed along with the gas: 



With the assistance of two sets of apparatus, by means of 

 which the gas could be alternately absorbed and again forced 

 out by insertion in water, fifty ordinary wine bottles of it could 

 be filled in one day, which, being carefully closed, were trans- 

 ported to Bonn, secured in vessels by means of water. 



In the mine of Wellesweiler, these pieces of apparatus for col- 

 lecting the gas were not necessary. The circumstance that this 

 gas was evolved from the floor of the mine, which was covered 

 by water to the depth of several inches, gave me good ground 

 for supposing that it must flow out with a pressure greater than 

 that of the atmosphere. I surrounded the funnel with a layer 

 of clay several inches deep, conducted the leaden tube luted 

 to it into a pneumatic trough filled with water, and found that 

 the gas could still overcome the pressure of a column of water 

 3 inches high. In three or four minutes, an ordinary bottle 



