10 



This experiment demonstrated the catalytic influence of the 

 silver and showed that this influence increases with the quantity 

 of silver. More precise quantitative results were not looked for, 

 as it was assumed that the action of the decomposed silver would 

 be deiDendent 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 likely that a 

 careful study of the form of the reaction curve for the pure 

 oxide would yield more trvistworthy information as to the law and 

 mode of action of this catalysis. 



A series of experiments was therefore carried out, sinlilar to the 

 one already described, but with more frequent and more accurate 

 determinations of the velocity. A considerable number of such 

 series was made at different temperatures, and of these I have 

 chosen the four most complete and satisfactory for further discus- 

 sion. These were made at 327.0° C, 332.5° C, 352.2° C, and 

 353.3° C, and may be designated by A, B, C, and D, respectively. 



The results are represented in fig. 2, the reaction velocity being 

 plotted vertically and the time horizontally. Instead of the time 

 when the experiment began, the time of maximum velocity is 

 taken as zero. Thus, the maxima of all the curves fall on the 

 same vertical line. The velocity is expressed as the fraction of the 

 whole quantity of oxide which is decomposed per second. This 

 can, of course, be readily found from the rate of evolution of oxygen 

 when the temperature and pressure and the weight of silver oxide 

 are known. If x represents the fraction of the original oxide that 



(JyX 



has been decomposed, the velocity is -7-. 



An inspection of these curves shows, as was to be expected, 

 that the maximum velocity is greater and, the whole time of the 

 decomposition less, the higher the temperature of the experiment. 

 Further, we are struck by the great regularity of the curves and by 

 their very evident similarity to one another. They appear to 

 belong to a single family of curves such as may be represented 

 algebraically by a single equation with one variable parameter. It 

 seemed likely that if these curves were reduced to the same scale 

 they might nearly coincide. 



This was attempted by plotting each experiment with a different 

 unit of time, so chosen as to make each maximum velocity equal 



