418 PROCEEDINGS OP THE AMERICAN ACADEMY. 



The speed of this reaction is represented by the equation 



dc 



^"~ , — /r C — A^ €-1 Co , 

 dt ^ ^ ' 



an expression which increases in magnitude as Co (the concentration of 

 the oxygen) diminishes. Since it is probable that P is very small, — 

 that the chief tendency of the reaction is from left to right, — this 

 cause of acceleration is not an important one. In a similar way the 

 decomposition of the oxides of nitrogen likewise accelerates the more 

 complex reaction into which the solids enter. 



In every case this decomposition of the oxide3 of nitrogen, and 

 therefore that of the cupric nitrate, had nearly advanced to completion 

 before the oxygen had all been expelled. This led to the existence of 

 a maximum* of gas volume after a brief heating, a maximum less marked 

 in the case of cupric oxide than in the other cases because the extra 

 oxygen escapes from cupric oxide almost as fast as it is formed. Thus 

 many of the apparent eccentricities in the behavior of the gases find 

 a simple and adequate explanation. The numerous results with differ- 

 ent oxides were sought in the hope that the relations might be capable 

 of quantitative proof according to the law of mass action, as well as of 

 qualitative demonstration, but the great number of possible compounds 

 and reactions made this hope vain. 



It remains only to devise an hypothesis to explain perhaps the most 

 interesting phenomenon under discussion, to show why the oxygen 

 is capable of escaping more rapidly than the nitrogen. Obviously diffu- 

 sion or transpiration cannot account for this ; for any orifice, no matter 

 how small, which would allow the oxygen to escape, must also allow the 

 nitrogen to escape. The only possible explanation is t^e supposition 

 that the oxygen finds its way out chemically, by uniting with metal or a 

 lower oxide which has momentarily released some of its proper supply 

 of oxygen. The displaced gas, being forced to find another berth, 

 presently in its turn occupies the place of still another portion, and 

 so on, until most or all of the excess has found its way out of prison. 

 Of course the nitrogen cannot use this means of escape, for it is not sur- 

 rounded by a compound which yields it upon dissociation ; the nitrogen 

 can only escape through holes originally present or formed by the re- 

 arrangement of the substance of the solid. 



This hypothesis suggests Grotthus's obsolete exjilanation of electroly- 

 sis, or rather that of Clausius ; for the most plausible conception is 

 that in the hot rapidly vibrating solid a portion of the oxygen which 



