186 Prof. Bischof (m the Inflammable Gases of 



By what process is it possible that these inflammable gases 

 can be produced in the interior of the earth ? The author of 

 the " jrdrmelehre'^ might easily be led to the hypothesis of 

 explaining its formation at the expense of the internal heat of 

 the globe. Were we, however, to assume that it is prodviced 

 in the same manner as the gas used for purposes of illumina- 

 tion, viz. by dry distillation from coal, we must take for granted 

 that the coal-formation extends downwards to a depth where 

 a red heat exists. But I do not for a moment doubt that such 

 an assumption vt^ould at once be contradicted by geology. I 

 would likewise add, that such a supposition is impossible on 

 chemical grounds. Thus, it is known that all inflammable 

 gaseS; which are obtained by dry distillation from coal and 

 other combinations of carburetted hydrogen, contain non-per- 

 manent inflammable gases (vapours) which are absorbed by 

 sulphuric acid. I have not, however, been able to find a trace 

 of such vapours in either of the two pit gases analyzed. I be- 

 lieve further, that from all the observations hitherto made, I 

 am entitled to assume that all inflammable gases obtained by 

 dry distillation contain carbonic oxide gas ; but careful and 

 repeated trials for this gas have afforded only negative results. 

 On the other hand, the resemblance in composition of the pit- 

 gas examined by me, and the so-termed marsh-gas, renders it 

 extremely probable, I might even say certain, that both have 

 the same origin. 



I found in pit-gases carburetted hydrogen as the chief com- 

 ponent, and carbonic acid and nitrogen in small quantity, pre- 

 cisely as in marsh-gas. As, therefore, marsh-gas is evolved 

 by a process of decomposition from organic debris, so also may 

 inflammable pit-gas be produced by the same process from coal. 

 In such a case the presence of water would be a conditio sine 

 qua non, and many phenomena point to the view that exhala- 

 tions of inflammable gases only occur where water comes in 

 contact Avith coal. The evolution of inflammable gas from coal 

 might, therefore, be a product of the continued carbonizing pro- 

 cess of the original vegetable fibres in the moist way ; a view 

 to which Karsten has already adverted in his investigations 

 regarding the carbonaceous substances of the mineral king- 

 dom (Berlin 1826, p. 231). That, otherwise, the internal heat 



