13 



The continuous curve sliown in fig., 3 is ol)taincil hy jJotting 

 this equation. Its great similarity to the experimental curves is 

 obvious. Still, it is not (juite identical with them. The experi- 

 mental curves all lie nearer to one another than they do to the 

 theoretical, and all show a certain assymetry which that does not. 

 In the case of the experimental curves it is evident that the apex 

 comes at a point where more than one-half of the silver oxide is 

 decomposed. Still the theoretical and experimental curves fall 

 much nearer together than was to have been predicted, and it is 

 possible that the existing difference may be due to faults in the 

 experimental method; thus, for example, it is not inipossibk; that 

 near the point of maximum velocity the reaction may take place so 

 rapidly that heat can not be absorbed from the bath rai)idly enough 

 to maintain a constant temperature, a condition which would 

 destroy the symmetry of the curve. Still it is hardly probable that 

 this was the case, for if it had been there would have been a wide 

 difference between the curves for the highest and the lowest 

 temperatures, since at the latter the maximum velocity is only 

 one-third or one-fourth as great as at the former. 



THE STUDY OF DIFFERENT VARIETIES OF SILVER OXIDE. 



In the experiments hitlierto described the same silver oxide was 

 used, namely, a preparation by Merck labeled "highest purity." 

 When this was exhausted the experiments were continued with an 

 oxide made by Eimer & Amend. However, it was soon found 

 that with this substance no results could be obtained comparable 

 with the preceding. The reaction velocity was far more rajiid than 

 with the old oxide. Thus, at 340" the maximum velocity was 

 passed in less than an hour, and in three hours all action had ceased. 

 Furthermore, the decomposition was irregular, so that under the 

 same conditions inconstant results were obtained. This sample of 

 oxide was therefore abandoned and another liottle of Merck's 

 procured. This was of the same grade and bore the same laltel as 

 that used in the previous experiments, but it too decomposed with 

 great rapidity. Thus, the velocity at 352° reached a maximum in 

 thirty-seven minutes and the reaction was over in three liours, 

 whereas with the original sample at this temperature the ninxiniuin 

 came at the end of four liours. The great irregularities sliown by 

 the Eimer «fe Amend samples, however, did not apju'ar. Sucli 

 irregularities most probably are due to lack of unifonnity in the 

 oxide. 



