1916] REED~—PEROXIDASES 235 
active by charging it with oxygen, either electrically (by making it 
an anode) or by a chemical method (exposing it to potassium 
permanganate). Obviously it was not possible to charge the plant 
peroxidase with oxygen elec- 
trically; hence the chemical 
method was adopted. To a 
about toocc. of the same $3 C 
peroxidase solution as that © 
used in the previous experi- = 
ment concentrated potas- 6 
sium permanganate’ solution 
was added drop by drop 
until the permanganate was 
no longer reduced, as shown sy 
by thecolor. A small excess 3 
of fresh extract was then 
added to reduce any free 
potassium permanganate 
present. The mixture was 
then filtered free from a 
small amount of brown pre- 
cipitate consisting of man- 0 
ganic hydroxide and ? 5 70 
probably also some organic HNO ES 
manganese compounds. In 
2.—Curves showing oxidation of 
this way a clear solution, 
somewhat deeper yellow in 
color than the original ex- 
tract, was obtained; but 
this solution possessed a 
very marked oxidative 
activity. Solutions of potas- 
sium iodide, gum guaiac, or 
Pyrogallol mixed with por- 
Fic. 
potassium iodide; lower ¢ curves whe on AB 
of hydrogen peroxide by horseradish -_ 
dase which had been treated with po 
permanganate at the beginning of ad serge: 
dation; curve OC represents oxidation by 
hydrogen peroxide in presence of untreated 
mixture; abscissae represent time in minu 
tions of it, were rapidly oxidized. This new compound was very 
unstable; when heated rapidly to 60° C. its ability to oxidize gum 
3A concentrated solution was used so that the amount added was not sufficient 
to dilute appreciably the peroxidase extract. 
