vin THE BURNING OF INFLAMMABLE GASES 153 



In these experiments, as in those of Dumas and of Dumas 

 and Stas, the purifying agents were distributed over pumice 

 stone, or broken glass, or were used in a granular form in 

 order to secure ample contact with the gas. The air in the 

 pumice stone was removed by repeatedly exhausting the 

 apparatus and filling it again with pure carbonic oxide. 



The copper oxide, prepared by calcination, was contained 

 in a glass tube drawn out at each end. Taps were pro- 

 vided so that the tube could be exhausted before weighing. 

 During the reduction the tube was heated quite gently over 

 charcoal. In a series of blank experiments the tube was 

 found to vary in weight by only a milligram on a total of 

 540 grams when heated, provided that some hours were 

 allowed to elapse before re-weighing. 



The gas escaping from the copper oxide tube was passed 

 through sulphuric acid to absorb any water that might be 

 formed ; the quantity collected was usually about ten milli- 

 grams. It then passed into a bulb containing potash, 

 where most of the carbonic anhydride was absorbed. A set 

 of Liebig bulbs filled with potash and three U-tubes, the 

 last filled with solid potash, 1 were used to absorb the 

 remainder of the gas. The weight of carbonic anhydride 

 was corrected for the buoyancy of the air displaced by the 

 increased bulk of the potash after absorbing the gas. 



The composition of carbonic oxide was shown by these 

 experiments to be : 



Oxygen 57 '16% 

 Carbon 42'84% 



C. MARSH GAS AND OLEFIANT GAS. 



The burning of inflammable gases. The existence of 

 inflammable gases other than those prepared by the action 

 of metals on the acids had been known from very early 



1 The solid potash served to prevent the loss of moisture from the 

 absorbing apparatus. 



