chemical change hy measurement of the gases evolved. 589 
Bate of evolution of gas, 
c.c. per minute, when 
x c.c. have been evolved 
X c.c. 
Bate of evolution of gas, 
c.c. per minute, when 
x c.c. have been evolved 
X c.c. 
5-71 
6 
2-64 
75 
5-13 
16 
2-13 
85 
5-00 
25 
1-68 
95 
4-39 
35 
1-26 
105 
3-88 
45 
0-89 
113 
3-45 
55 
0-73 
117 
3-03 
65 
6 
o C.C.. 20 40 60 &0 100 \20 140 
Volume of gas evolved 
Fig. 3. 
is calculated, using the value for A determined in this manner, 
the well agreeing numbers given in the earlier tables are obtained. 
In all the experiments at higher temperatures, the greater velocity 
of the reaction enabled readings to be taken very near the end of 
the reactions, the end-point being actually observed, and found to 
be in perfect agreement with the value calculated as above from 
the earlier observations, and the reactions were still unimolecular 
to the end. The range investigated however does not represent 
