726 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



decomposition of hydrogen arsenide, hydrogen selenide, and hydrogen 

 antimonide, respectively, by Cohen,* Bodenstein,t and Stock and Gutt- 

 manu.$ In all these cases in heterogeneous systems a reaction in a 

 liquid or gaseous phase is catalyzed by a solid product. Bodensteiu,§ re- 

 calculating the work of Stock and Guttmann, points out the surprising 

 simplicity and regularity of the decomposition studied by them. But 

 how much more surprising it is that in our present case the decomposition 

 of one solid is catalyzed even more smoothly and regularly by the pres- 

 ence of another solid with which, in the very nature of solid substances, it 



Figure 3. 



cannot be in very intimate contact. In fact, this decomposition behaves 

 like a simple homogeneous reaction. 



In a homogeneous catalytic reaction the simplest case is that in which, 

 for a given volume, the reaction velocity is proportional to the quantity 

 of the reacting substance and to the quantity of the catalyzer. Let us see 

 how nearly the decomposition of silver oxide conforms to these conditions. 



If we assume that the velocity of reaction is proportional to the quan- 

 tity of silver oxide and of silver, we may write the equation, 



dx 



(it 



=: Kx (1 — x), 



0) 



* Z. r. C, 25, 483 (1898). 



X Ber. a. (k'utscli. Cliem. Ges., 37, 901 (1U04). 



t Z. P. C, 29, 420 (189<.1) 

 § Z. r. C, 49, 41 (1004). 



