278 Dr. Henry on the Anali/sis of Gaseous Mixtures 



Before Firing. After Firing. 



Measure of Measure of Measure of Oxygen to Oxygen to 

 Carb. Oxide. Hydrogen. Oxygen. I Carb. Oxide. Hydrogen, 



Exp. 



When equal volumes of carbonic oxide and hydrogen gases, 

 mixed with oxygen sufficient to saturate only one of them, 

 were exposed in a glass tube to the flame of a spirit lamp, with- 

 out the presence of the sponge, till the tube began to soften, 

 the combination of the gases was effected without explosion, 

 and was merely indicated by a diminution of volume and an 

 oscillatory motion of the mercury in the tube. At the close of 

 the experiment, out of twenty volumes of oxygen, eight were 

 found to have united with the carbonic oxide, and twelve with 

 the hydrogen — proportions which do not materially differ from 

 the results of the first experiment in the foregoing table. At 

 high temperatures, then, the attraction of hydrogen for oxygen 

 appears to exceed that of carbonic oxide for oxygen : at lower 

 .temperatures, especially when the gases are in contact with the 

 platinum sponge, the reverse takes place, and the affinity of 

 carbonic oxide for oxygen prevails. 



Extending the comparison to the attraction of olefiant and 

 hydrogen gases for oxygen at a red heat, I found that when 

 six volumes of olefiant, six of hydrogen, and three of oxygen 

 were heated by a spirit lamp till the tube softened, a silent 

 combination took place as before ; all the oxygen was con- 

 sumed, but only half a volume had been expended in forming 

 carbonic acid, which indicates the decomposition of only one 

 quarter of a volume of olefiant gas. On attempting a similar 

 comparison between carbonic oxide and olefiant gas, by heat- 

 ing them with oxygen in the same proportions, the mixture ex- 

 ploded as soon as the glass became red-hot, and burst the tube. 



The property inherent in certain gases, of retarding the ac- 

 tion of the platinum sponge, when they are added to an ex- 

 plosive mixture of oxygen and hydrogen, is most remarkable 

 in those which possess the strongest attraction for oxygen ; 

 and it is probably to the degree of this attraction, rather than 

 to any agency arising out of fheir relations to caloric, that 

 we are to ascribe the various powers which the gases manifest 

 in this respect. This will appear from tlie following table, 

 the first column of which shows the number of volumes of each 



gas required to render one volume of an explosive mixture of 

 ydrogen and oxygen uninflammable by the discharge of a 

 Leyden jar ; while the second column shows the number of 

 volumes of each gas necessary in some cases to render one 



volume 



