140 Dr BischoPs Examination of Three Inflammable Gases 



according to the determination by means of chlorine, not ex- 

 ceed 0.0025 vol. in amount. 



The same experiments as in § v. (vol. xxix. p. 320), for the 

 discovery of carbonic oxide gas, were also performed with this 

 gas. The mercury was boiled in the tube, and the potassium 

 was at first only heated to melting. The gas increased about 

 0.146 of its volume Afterwards the potassium was again 

 heated, and for so long as an increase of volume could be re- 

 marked, during which the tube acquired a dark red heat. 

 The increase altogether amounted to 0.184 of its original 

 volume. 



Since these experiments, as well as those in § v., indicated no 

 carbonic oxide gas, but, on the contrary, always presented an 

 increase of volume, it seemed to me interesting to ascertain 

 the action of potassium with an inflammable gaseous mix- 

 ture, which actually contained carbonic oxide gas. In order 

 to be quite certain that the carbonic oxide gas was free from 

 carburetted hydrogen gas, I obtained it from oxalic acid by 

 means of sulphuric acid, and carefully separated the carbonic 

 acid gas. As the pit-gas from JFellesweiler Stollen proved to 

 be a pretty pure carburetted hydrogen gas, I conducted 4 

 vol of this gas, and 1 vol. carbonic oxide gas into a tube filled 

 with boiled mercury, and dried it by means of chloride of cal- 

 cium. 1 continued the heating of the potassium so long as 

 an alteration of the volume of gas could be perceived. A di- 

 minution of it took place, but it amounted only to 0.075. 

 The potassium therefore only indicated 0.075 vol. of the 0.2 

 vol. which had been added. 



As accordingly it was to be supposed, that potassium only 

 indicated carbonic oxide gas in an inflammable gaseous mix- 

 ture, when it was present in considerable quantity, I repeated 

 the preceding experiment with a gaseous mixture which con- 

 tained only £th of its volume of carbonic oxide. When the 

 potassium was heated to the melting paint, a diminution of 

 volume of 0.02 presented itself, after the tube had been brought 

 back to its original temperature. When, on the contrary, the 

 potassium was heated anew and uninterruptedly until the 

 volume was no longer altered, an increase of 0.098 presented 

 itself after cooling. 



