Ill 
standing, however, such boiled solutions regain their activity. That 
such is the case was first observed by Woods ( 463 ) in his study of the 
peroxidase of tobacco, and has been accounted for by Woods, and 
also by Aso( 16 ), upon the supposition that the peroxidase is regen- 
erated from zymogens which are more stable towards heat and 
various reagents than the ferment itself. Bach and Chodat ( 27 ) find 
that a second heating destroys the peroxidase altogether; so also an 
alcoholic solution of the ferment is destroyed by heating to the 
temperature of boiling alcohol. The interval required for the 
destruction of the enzyme has been found to vary with the concen- 
tration of its solution. Thus when diluted with twenty times its 
volume of water a given specimen which in its original dilution 
required eighteen minutes in boiling water for complete destruction, 
required but three minutes at this temperature when thus diluted. 
According to Bach ( 19 ) the peroxidase is a single enzyme, whose func- 
tion is to activate hydrogen peroxide in the oxidation of substances 
containing labile hydrogen. 
Bach and Tschermiack ( 32 ) have given detailed directions for the 
purification of peroxidase. No essential differences have been 
observed between the conduct of crude peroxidase and that of the 
purest preparations. The pure preparations were found to contain 
6 per cent of ash; this ash was found to be iron-free, but to contain 
aluminium and manganese. Bach and Chodat ( 27 ) found that 
peroxidase, the chief constituent of oxidase, contains nitrogen and 
gives the p} 7 !*^ reaction. They conclude, however, that it is not a 
proteid since neither the raw product nor the purified enzyme show 
the protein reactions. 
According to Bach and Chodat ( 27 ) the action of peroxidase is 
specific in that it strongly activates hydrogen peroxide and other 
peroxides in a large number of oxidation processes, such as the 
oxidation of pyrogallol, gallic acid, anilin, dimethylanilin, etc. They 
observed further that while it strongly activates small amounts of 
hydrogen peroxide, it is destroyed by larger amounts of the peroxide 
( see also Schoenbein ( 379 ), p. 474), and also that in the absence of 
hydrogen peroxide or a similar substance the peroxidase has no 
oxidizing power ( see also Linossier ( 273 )). Decidedly the most 
interesting observations recorded by these observers is that the 
peroxidase not only activates hydrogen peroxide and the peroxides 
resulting from the slow oxidation of various organic compounds such 
as ether, alcohol, and the essential oils, but that it also has the power of 
increasing the oxidizing power of the oxidases. As elsewhere pointed 
out, Moore and Whitley ( 306 ) argue from this that the oxidase is 
nothing more than a mixture of peroxidase and an unstable, naturally 
occurring peroxide ( see also Bach and Chodat ( 28 )). 
