2a C. W. R. POWELL. 
confirm the latter conclusion the course of the reaction 
was studied more closely by noting the time that any par- 
ticular reaction took to reach some definite stage, say one- 
eighth or one-sixth of the total decomposition. 
Table C.—Influence of the acid concentration on the velocity of 
reaction. 
5° ©, 
Acid cone. Time taken to decompose. 
One-eighth. One-sixth. One-half. 
29 NC 75 90 170 
“DS 3; 53 61 102 
L2hG 5, 31 39 60 
1 ae 6 
"058 N. 52 64 ae 
MD: di 46 53 94 
ei See sta $e 56 
“8 +5) 18 23 4] 
Lelib 12 15 24 
If, as concluded, the nature of the reaction is not altered 
by varying the concentration of sulphuric acid in the solu- 
tion, then the increase in the velocity of reaction caused 
by increasing the hydrogen ion concentration should be the 
same at any stage of the reaction. An examination of 
Table C. showed this to be the case, and the fact was made 
much clearer by expressing the relation between the figures 
for different experiments as in Table D, where the increase 
in the velocity of reaction caused by increasing the acid con- 
centration from °58 N. to 1°16 N. is expressed by dividing 
the time taken to decompose a definite fraction of the whole 
at the lower concentration by the time taken to decompose 
a Similar amount at the higher acid concentration. 
Table D. 
Temperature Stage at. which reactions compared. 
Gs One-eighth. One-sixth. Half-way. 
5 Led 1:56 Li, 
15 1:50 153° 1-71 
