23 
for the formation of hydrogen peroxide in certain oxidations on the 
supposition that this compound is formed by the oxidation of water 
by an atom of active oxygen. Thus he explained the formation of 
hydrogen peroxide during the oxidation of metals in the following 
manner : 
M+ 0 2 = MO + O, 
and 
• h 2 o+oIh 2 o 2 . 
The principal objections which have been urged against this theory 
are, first, that it fails to take into account the formation of peroxides 
other than hydrogen peroxide as the result of processes of autoxida- 
tion, and, second, that it accounts for the formation of hydrogen 
peroxide in processes of aut oxidation on the assumption that this 
compound results from the oxidation of water. It is now known 
that many peroxides other than hydrogen peroxide are produced 
during processes of autoxidation, and it was pointed out by Welt- 
zien ( 446> 447 ) as early as 1860 that hydrogen peroxide can not be re- 
garded as oxidized water. (See also Bach ( 18 . ) While it was afterwards 
claimed by Richardson ( 343 > 347 > 348 ) that water is oxidized during the 
oxidation of ether by oxygen in sunlight, apparently the precise 
conditions for accomplishing this oxidation have never been described, 
and Dunstan and Dymond ( 153 ) have shown that hydrogen peroxide 
is never produced by the action of oxygen on water under the influ- 
ence of light and heat, even in the presence of dilute sulfuric acid. 
We know now that hydrogen peroxide is formed during the autoxida- 
tion of various substances, sometimes as the primary product of the 
oxidation of labile hydrogen atoms or hydrogen ions; more frequently 
as a secondary product resulting from the hydrolysis of another 
peroxide previously formed during the autoxidation, but never by 
the oxidation of water. 
In a series of remarkably interesting and suggestive communica- 
tions extending over a period of eleven years, from 1882 to 1893, and 
published for the most part in the Berichte der Deutsehen Cherni- 
schen Gesellschaft, Mauritz Traube ( 431 ) laid the foundations of the 
peroxide theory of oxidation and enriched the nomenclature of the 
subject with many valuable terms, such as “autoxidation/’ “autoxi- 
dizable/’ “holoxide/' etc. The clue to an understanding of 
Traube’s peroxide theory of oxidation is to be found in the fact that 
water is necessary for most if not all oxidations proceeding spontane- 
ously at ordinary temperatures and that hydrogen peroxide is pro- 
duced as one of the products in all or at least in nearly all of those 
oxidations that are effected by molecular oxygen. He ( 433 ) made the 
interesting observation that pure metallic sodium retains its bright 
luster for forty hours in an atmosphere of dry oxygen, whereas it is 
instantly tarnished the moment that a trace of moisture is. admitted. 
