320 H. B. TAYLOR. 
50 cc. of milk and 20 cc. of N/5 sulphuric acid. The solu- 
tion is then filtered, and the filtrate analysed for its hydrogen 
peroxide content, by comparing the colour produced on 
adding excess of titanium sulphate with that obtained 
when the titanium solution is added to a standard solution 
containing a known amount of hydrogen peroxide. In the 
second method a purified solution of catalase was used, 
Experiments were carried out at 25° O. with mixtures of 
50 cc. of milk and 15 cc. of M/10 hydrogen peroxide, ard 
the concentration of the hydrogen peroxide determined 
from time to time. In Table I are given values for X, the 
velocity constant, calculated as a first order reaction, from 
figures obtained by the method described above. In order 
to obtain the true catalytic action of the enzyme, it is 
assumed, in the calculation of A, that the concentration of 
the hydrogen peroxide at the end of the reaction is zero 
(i.e., assuming that the enzyme catalyses the reaction as 
an ideal catalyst). 
Table I. 
Temperature 25°C. K = 23 log 2 
a—-iX. 
ae toe t ax K x 10# 
M/47 ) 1:70 oe 
| 30 9) |t legs 69 
| 40 1:30 67 
| 84 “96 68 
tat oa ee 82 60 
| 1490 40 
Where a = initial concentration of hydrogen peroxide 
anda — x = concentration at time t. The hydrogen per- 
oxide used had been ‘previously purified by redistillation 
under reduced pressure. 
Working with a number of different samples the velocity 
constants obtained were not by any means the same, even 
