590 Mr Lamplougli, On the determination of the rate of 
the whole course of the reaction, because a delay occurs between 
the mixing of the solution and the first reading, this delay being 
T5 minutes at 51 0, 4 and lesser amounts in experiments at lower 
temperatures. Even assuming that there is no “induction period” 
of slow rate of reaction, and that the liquid throughout this delay 
is at the same temperature as that during the rest of the ex- 
periment, this time corresponds to a loss of 19'3 c.c. of gas 
unmeasured, and thus at 51 0, 4 the range investigated is from 
16°/ 0 to 99'0%- In reality the range is greater than this, because 
the reacting liquid is at a lower temperature during part of the 
delay, and therefore decomposing less rapidly. 
At 44 0, 3, with a loss of T3 minutes the range investigated 
is 5’8°/ 0 to 90'4°/ o . At the lowest temperature, 36°, the loss 
in time was only IT min. and the rate of reaction slow, causing 
a loss of not more than 3'2 c.c. of gas, so that the reaction was 
investigated from less than T6 0 / 0 up 1° 60 °/ 0 . No departure 
from the law of a unimolecular action was observed throughout 
the above ranges, and therefore from the point at which the 
reaction has proceeded less than T6°/ 0 the unimolecular equation 
accurately represents the course of the reaction, and there is 
no suspicion of any irregularity whatever at the beginning of the 
reaction. 
Experiments were subsequently made at 40° and 55° to 
determine whether any thermal change due to the reaction caused 
the temperature of the reacting liquid to differ from that of the 
water bath. In these experiments a vessel of similar capacity to 
that described, and containing a thermometer, but not adapted for 
the measurement of evolution of gas, was used. At both tempera- 
tures it was found that during the time throughout which 
measurements had been recorded, the difference of temperature, if 
such existed, between the reacting liquid and water bath did not 
exceed '1°. 
The following table gives the values of the constant K and of 
the logarithms of the constant for the different temperatures at 
which the experiments were performed. 
Temperature 
K 
Log IC 
36° 
•0065 
3-8129 
44°-3 
•0198 
2-2967 
[50° 
•0424] 
51°-4 
•0511 
2-7084 
60° 
•147 
1-1673 
67° 
•345 
1-5378 
