312 Dr Bischof 8 Examination of Three Inflammable Gases 



gas comes from a depth of 322 feet. The place where the 

 gas issues forth is 210 feet under the surface of the earth ; 

 and hence it would appear that the gas comes from a depth of 

 112 feet under the gallery. It may however, with probability, 

 be assumed, that the gas on its passage is exposed to refrige- 

 rating influences, inasmuch as it passes through colder strata 

 and meets with colder water ; hence the original temperature 

 of the gas may have been higher than 55°.7 F. ; and the 

 current may have come from a greater depth. 



A second blower occurs in an old deserted mine near 

 JVellesweiler^ about twenty English miles from Saarbriicken. 

 It was reached about forty or fifty years ago, and since 

 1816-17 has been included in a copper funnel with a pro- 

 longed pipe. It occiu-s in a principal fissure in slate-clay at 

 the bottom of the gallery. At some distance from the blower, 

 a bore has been made for 119 feet under the floor of the mine, 

 and a stratum of coal from seventy to eighty inches thick has 

 been found at a depth of forty -five feet. 



I found this current of gas still surrounded by the above- 

 mentioned funnel, which I employed for the collecting of the 

 gas. This current is much smaller in quantity than that in 

 Gerhard's Stollen^ for the flame of the gas was only 2 to 3 

 inches high. But the gas was just as devoid of smell and 

 taste, and burned like the other, with a flame that was yellow 

 above and blue beneath. 



The temperature of the gas was 54°.6 F., and that of the 

 rock 51°.6 F. The above-mentioned data being assumed, 

 the gas must have come from a depth of at least 155 feet. 

 The same remarks are applicable to this case as to the other, 

 and hence it is likely that the depth is greater than I have 

 just stated. 



I have already mentioned, that the gas in Gerhard's Stollen 

 cannot be collected in the usual manner, in a pneumatic 

 trough. The apparatus which I employed for the purpose. 



between the galleries and the external atmosphere doubtless causes the 

 stone, to the depth of several feet, to partake of the changes of temperature 

 of the external atmosphere. On the 30th September, when I made the 

 above observationB, the temperature of the surface of the earth was some 

 degrees above tlie mean. The observed temperature of the rock (64°.7 F.), 

 therefore, was also of course above the mean^ 



