724 



PROCEEDINGS OF THE AMEUICAN ACADEMY. 



.55 gram silver, aud the third (C) was left pure. All three were sub- 

 jected to precisely the same treatment of rubbing and stirring, and intro- 

 duced in separate tubes simultaneously into the thermostat. At the end 

 of three quarters of an hour 1 c.c. of gas was evolved from A in seventy- 

 two seconds, from B in eighty-five seconds, and from C in two hundred 

 and fifteen seconds; at the end of an hour, from A in forty-two seconds, 

 from B in fifty-six seconds, and from C in two hundred and ten seconds. 

 The velocity reached its maximum for A in eighty-eight minutes, for B 

 in one hundred and ten minutes, aud for C in one hundred aud sixty 

 minutes. 



Figure 2. 



This experiment demonstrated the catalytic influence of the silver and 

 showed that this influence increases with the quantity of silver. More \)Ye- 

 cise quantitative results were not looked for, as it was assumed that the 

 action of the decomposed silver would be dependent upon the degree of 

 fineness, the intimacy of its mixture with the oxide, and possibly upon 

 other conditions which could not be made entirely uniform. It seemed 

 more likely that a careful study of the form of the reaction curve for the 

 pure oxide would yield more trustworthy information as to the law and 

 mode of action of this catalysis. 



A series of experiments was therefore carried out, similar to the one 

 already described, but with more frequent and more accurate determina- 

 tions of the velocity. A considerable number of such experiments were 

 made at different temperatures, and of these I have chosen the four most 



