DISOXIDATION EFFECTED BY THE ALKALINE PEEOXIDES. 
847 
m=the parts of the solution of peroxide of hydrogen decomposed in the experiment; 
mj=:the parts of the solution of chromic acid decomposed in the same experiment; 
a:=the ratio of the oxygen evolved from the peroxide of hydrogen to the oxygen 
evolved from the chromic acid in the same experiment ; 
then 
ms 
W= 
Also, putting 
w=the parts of the solution of peroxide of hydrogen employed in the experiment ; 
Wj = the parts of the solution of chromic acid employed in the same experiment; 
r=the ratio of the oxygen contained in the peroxide of hydrogen to the oxygen con- 
tained in the chromic acid employed in the experiment ; 
then r= 
This ratio I shall term the ratio of mass. 
Further, putting 
p=\he parts of the iodine solution equivalent to the excess of peroxide of hydrogen 
after the completion of the decomposition ; 
the parts of the iodine solution* equivalent to the excess of chromic acid after 
the completion of the experiment, as determined by the formulaj9=w^ — ; 
then 
ms ns—p 
^ m^s^ rijSi — Pi 
where either^ or^i = 0, according as the chromic acid or peroxide of hydrogen is in 
excess. 
And if y be the ratio of the difference of the amount of oxygen contained in the per- 
oxide of hydrogen and the amount of oxygen contained in the chromic acid employed, 
to the amount of oxygen evolved from the chromic acid decomposed, then 
y= 
ns — riiSi 
njSi-pi 
^ 1^1 
n^Si-pi 
(r-1). 
So long as the chromic acid is not in defect, the whole of it being decomposed, 
y=r—\. If the oxygen in the peroxide of hydrogen be equal to that in the chromic 
acid employed, y=0 ; if this oxygen be greater in amount than that in the chromic acid, 
y is positive, if less, y is negative. 
Also 
X ns—p 
y ns — njSj 
The numerator of this fraction represents the number of atoms of oxygen evolved 
* In these experiments a proportionate part of the solution was titred after the completion of the 
reaction, and the values of ^ and p^ calculated. In strong solutions the error, from this cause, is accumu- 
lated and may become considerable. To this may be attributed the deviation from the mean in experiments 
1, 3, and 4 of the following Table. 
5 z 2 
