850 
PEOFESSOE B. C. BEODIE ON THE OXIDATION AND 
changes which are capable of being separated, from the circumstance that they take 
place with very unequal rapidity. 
A definite period in the decomposition is marked by the disappearance of the blue 
compound. At this point the solution was titred, and the loss of oxygen estimated. 
The progress of the decomposition was followed by means of the same experiment until, 
finally, the maximum loss was attained. I give two series of experiments, in which the 
substances were taken in difierent proportions. 
I. 
Time of titration. 
s. 
Sj. n. 
fty 
1. After decomposition of] 
17-594 
7-160 4P 
4P 
41-98 ] 
blue compound . .1 
— 
— 
41-88 j 
2. After ^ an hour . . , 
17-183 
7-023 4P 
4P 
32-864 
3. After 2 hours 
— 
— 
28-056 
4. After 18 hours , . 
— 
— 
27-656 
These data give the following values for r. 
y, and a : : — 
r. 
y- 
Mean. 
1. 2-47 
1-47 
[0-997 1 
11-0033/ 
1-001 
2. 2-446 
1-446 
1-277 
1-277 
3. 
1-448 
1-448 
4. 
II. 
1-462 
1-462 
Time of titration. 
s. 
Sj. n. 
ny 
P- 
1. Immediate .... 
17-594 
7-101 6P 
4P 
76-9561 
76-207J 
2. After 1 hour .... 
— 
— 
60-12 
3. After 1| hour .. . . 
— 
— 
4. After 2 days .... 
— 
— 
57-114 
Hence we have 
r. 
y- 
X, 
Mean. 
1. 3-705 
2-705 
1-007] 
1-033J 
1-020 
2. 
1-593 
1-593 
3. 
1-593 
1-593 
4. 
1-703 
1-703 
It thus appears that the decomposition takes place in two stages, the former of which 
is complete immediately after the destruction of the blue compound, and in which the 
two substances lose equal amounts of oxygen ; while the latter requires several homrs 
for its completion, the solution during this time being in a continual state of change. 
