310 Dr Bischof s Examination of Three Inflammable Gases 



coal-formation in Gerhard's stollen. By inserting in the fis- 

 sure a tube, and luting it with clay, the evolved gas could be 

 ignited, and it burned with a blue flame three or four inches 

 in height. The flame was so perfectly blue and without a 

 trace of yellow, that, when it was compared with the bluish- 

 yellow flame of the inflammable marsh gas, one was inclined 

 to regard the evolved gas rather as carbonic oxide gas than 

 as carburetted hydrogen. I endeavoured, by means of a small 

 pneumatic trough, to collect some of it ; but it was not pos- 

 sible, as the gas could not overcome the pressure of the small- 

 est column of water. Having become aware of this circum- 

 stance, I turned my attention to other means in order to be 

 able, on my second visit to Gerhard'' s Stollen in the autumn 

 of 1838, to collect the desired quantity. 



Physical Relations of the Inflammahh Gaseous Exhalations in the 

 Coal-pits of Saarhrilcken. 



I have already described the mode in which the inflam- 

 mable gas issues forth in Gerhard s Stollen in Louisenthal. 

 When, in the year 1838, I visited the place for the second 

 time, a tube was inserted with greater care than before, and 

 the fissure, as far as it could be followed up, was spread over 

 with clay. The gas now burned with a flame which was 

 twelve to fifteen inches in height, but which was not as for- 

 merly of a pure blue colour, but was only blue beneath, and 

 yellow above. I shall afterwards shew that the same inflam- 

 mable pit-gas can burn with diff^erent coloured flames under 

 diff'erent circumstances. 



If we allow a continuous stream of the gas to be directed 

 on the tongue or into the nose, we can neither remark a dis- 

 agreeable taste nor smell. It was tasteless, and without 

 odour. The miners told me that they had never noticed a 

 peculiar smell in fire-damp, but they had experienced a pres- 

 sure on the eyes and the temples. This induced me to allow 

 the gas to flow into my eyes for some minutes. I experienced, 

 however, nothing peculiar in the eyes ; but others, who re- 

 peated this experiment, said that they felt a peculiar sensa- 

 tion in the eyes or temples. ;; 



The high flame of the gas, as it issued either directly from 



