117 
Jones and his co-workers ( 232 , 233 ) have recently investigated the 
lowering of the freezing point of certain salts and acids in aqueous 
hydrogen peroxide as a solvent. In discussing the abnormal lower- 
ing of the freezing point of certain of these salts, such as potassium 
nitrate, in this solvent, these observers make this significant state- 
ment: “The most probable explanation of the above results, all 
things considered, seems to be that there is union between the mole- 
cules of the salts investigated and the molecule of hydrogen peroxide.” 
According to Manchot ( 284 ) the apparent reductions by means of 
hydrogen peroxide are in reality due to the formation of more highly 
oxidized primary products, which ultimately break down into final 
products which are less highly oxidized than the hydrogen peroxide 
itself. (See also Kastle and Loevenhart.) 
There seems to be abundant evidence, therefore, that hydrogen 
peroxide is not only able to form peroxides by double decomposition, 
but that it also frequently combines directly 'with various substances 
to form complex unstable addition products, and that oxidations by 
means of this substance are often greatly accelerated and its decom- 
position greatly hastened by the formation and subsequent decompo- 
sition of these complex substances. It wouid seem logical, therefore, 
to look upon the peroxidases as substances capable of forming unstable 
peroxides from hydrogen peroxide by double decomposition, or of 
combining directly with hydrogen peroxide to form unstable holoxide 
(Traube) or moloxide (Engler) derivatives, possessing greater 
powers of oxidation than hydrogen peroxide. 
Thus, if we designate the peroxidase by P, and the second oxidiz- 
able substance by P, the oxidations effected by the peroxidase might 
be represented diagrammatically as follows : 
P + H 2 0 2 = P0 2 + H 2 0, 
and P0 2 + P = PO + BO, 
x or P0 2 + 2P = P + 2P0, 
or P + H 2 0 2 = H 2 P0 2 , 
and H 2 P0 2 + B —■ P + BO + H 2 0. 
As already pointed out, these views respecting the mode of action of 
the peroxidases are shared by Bach, who has observed that when a 
mixture of a peroxidase and hydrogen peroxide is allowed to stand for 
some time both disappear from the solution, a fact which indicates 
the mutual interaction of these two substances. According to Bach 
and Chodat ( 27 ) the peroxidases exert not the slightest oxidizing action 
in the absence of the peroxide. On the other hand, they found that 
it can activate not only hydrogen peroxide but also organic peroxides, 
such as ethyl-hydroperoxide, C 2 H 5 0 2 H. Further, they have shown 
that the system (peroxidase + peroxide) accomplishes precisely the 
