— 
26 
Fourth. Contrary to the views of Hoppe-Seyler it is not the oxygen 
molecule which is decomposed in autoxidations, but the molecule of 
water, whereby atomic hydrogen is formed, which then combines 
directly with the molecular oxygen to form hydrogen peroxide. 
Digramatically the essential points of difference between these two 
theories of oxidation may be represented as follows: 
M+ O] :[0 + H 2 0 = MO + H 2 0 2 (Hoppe-Seyler), 
and 
■ ¥+ Ho]’[h + ° != j/(0H ) 2 + H 2°2 (Traube); 
The weak point in Hoppe-Seyler's theory is that it explains the 
formation of hydrogen peroxide by the oxidation of water. On the 
contrary, everything points the other way, viz, that water results 
from hydrogen peroxide by loss of oxygen, either as the result of 
decomposition or through the action of oxidizable substances. 
The objection to TrauHe s theory is that it has not been possible 
to prove the presence of hydrogen peroxide among the products of 
all autoxidations. Thus Cushman ( 128 ) obtained no evidence of it 
in his recent study of the corrosion of iron. Traube, however, explains 
its absence in certain autoxidations on the ground that it is decom- 
posed as fast as formed by the other substances produced during the 
oxidation. Thus in the case of the slow oxidation of iron it is prob- 
able that the hydrogen peroxide resulting from the first phase of the 
oxidation is partly consumed in the further oxidation of the ferrous 
hydroxide to iron rust. It should also be borne in mind that hydro- 
gen peroxide is also decomposed into water and ox} T gen by most, if 
not all, of those substances whose oxidation it can accomplish, so that, 
all things considered, it is not surprising that it should occasionally 
be found to be absent from solutions in which autoxidation processes 
are taking place. 
During recent years the peroxide theory of oxidation has been con- 
siderably extended through the labors of Bach, Engler, and Manchot, 
and their coworkers in this field. In the main the work of these 
several observers has consisted in the extension and elaboration of 
Traube’s peroxide theory of oxidation. Thus in 1897 Bach ( 18 ) 
investigated the slow oxidation of a large number of substances and 
arrived at the conclusion that readily oxidizable substances combine 
with partially dissociated molecular oxygen, — O — O — , a to form per- 
oxides, and that these latter substances when once formed promote 
and accelerate the oxidation of any other less readily oxidizable sub- 
stances that may happen to be present. He also came to the con- 
clusion that the oxidizing ferments of the blood are in reality readily 
oxidizable substances, having a special aptitude for forming per- 
oxides. Similar conclusions have been reached by other chemists 
respecting the nature of the plant oxidases. 
a See von Helmholtz and Richarz ( 20S ). 
