DISOXIDATION EITECTED BY THE ALKALINE PEEOXIDES. 
839 
The parallel character of this reaction to that of the reduction of the metallic oxide is 
sufficiently evident. Nevertheless it was desirable absolutely to realize the normal 
change in the case of the oxide itself, and to discover a case in which the catalytic 
action should be eliminated. 
In the paper referred to I gave several examples of the decomposition of the alkaline 
peroxides, effected by the action of oxidizing substances in aqueous solution — such, 
for example, as the decomposition of the peroxide of hydrogen by chlorine and by 
permanganic acid, and of the peroxide of barium by the alkaline hypochlorites and by 
a solution of ferricyanide of potassium. These reactions are free from the complicating 
circumstances before mentioned. The present paper contains an investigation of several 
of these decompositions ; it will be seen that they follow the normal law of chemical 
action, that is, the two substances which enter into the change are decomposed in a simple 
atomic ratio, and that these decompositions differ from other chemical changes in no 
single respect, and need, to account for them, no special hypothesis. 
The experiment discovered by Baereswil, of the reduction of the peroxide of 
hydrogen by chromic acid, presents points of special interest. We have in this case 
an action varying with the proportion present of the decomposing substances, and 
apparently of an abnormal character, which, however, is shown by accurate investigation 
to be subject to the atomic law, and to be capable of being broken up into two simple 
reactions. 
From the effects of reduction I proceed to consider the effects of oxidation produced 
by the alkaline peroxides, which are of considerable theoretical importance. Certain 
theories have been formed as to the different nature of the oxygen in the different classes 
of peroxides, based on a supposed difference in the properties of this oxygen. It will 
be shown that the difference of properties, to account for which these hypotheses have 
been invented, does not exist, and that, by suitable modification of the circumstances 
of the experiment, the results of oxidation produced by the peroxide of manganese may 
equally be realized by the peroxide of barium. 
Lastly, I shall give some experiments on the catalytic decomposition which this class 
of peroxides undergoes, instituted -with the view of discovering the cause of this action, 
and the way in which these phenomena are connected with the ascertained properties 
of the peroxides. This form of decomposition I believe to be the consequence of that 
double function of oxidation and reduction which is peculiar to this group of sub- 
stances. 
In the experiments which follow, which were made by means of standard solutions, 
the amount of solution employed was measured by the aid of a series of carefully cali- 
brated pipettes, which were so arranged that the capacity of each was an exact multiple 
of the capacity of the smallest pipette. The capacity of this pipette, which I shall 
designate as P, was equal to 4-55 cub. centims. The other pipettes are designated as 2 P, 
3P, ...lOP, &c. 
5 y2 
