44 
It is evident from these results that saliva, extract of malt, potato 
peel, horse-radish, blood, and copper sulfate conduct themselves 
very differently toward the four phenolphthalin reagents. Properly 
interpreted they go to show, first, that the potato peel contains both 
an oxidase and a peroxidase; second, that saliva, extract of malt, and 
horse-radish contain a peroxidase; third, that blood contains neither 
an oxidase nor a peroxidase, but that both raw and boiled it is 
capable of oxidizing phenolphthalin in alkaline solution either alone 
or through the agency of hydrogen peroxide; fourth, that copper 
sulfate at great dilutions contains nothing which acts like an oxidase 
or peroxidase, but that like blood it is capable of strongly inducing 
the oxidation of phenolphthalin in alkaline solution by hydrogen 
peroxide, but that it differs from blood in not being able to oxidize 
an alkaline solution of phenolphthalin alone, or if it does so, it is only 
with extreme slo^vness as compared with blood; and we can readily 
distinguish between an aqueous extract of horse-radish and blood, 
the former containing probably the most powerful peroxidase knovm, 
by the fact that it (horse-radish) readily oxidizes a neutral solution 
of phenolphthalin containing hydrogen peroxide, whereas blood does 
not, and further by the fact that the peroxidase of horse-radish does 
not oxidize either an alkaline solution of phenolphthalin alone (2) 
or one containing hydrogen peroxide (3), or at least only with extreme 
slovmess as compared with blood, and thirdly by the fact that the 
slight oxidizing power which the peroxidase of horse-radish exhibits 
toward reagents (2) and (4) is entirely lost on boiling, whereas 
boiled blood solutions are very active toward both of these reagents. 
Concerning the action of pus, it may be said that my own experience 
has been that pus differs from blood in that it contains a true peroxi- 
dase the activity of which is lost on boiling. Thus I have found 
unboiled extracts of pus to oxidize reagent (3), whereas with the 
boiled extracts no oxidation occurred. This has been the experi- 
ence of other chemists. Thus Brandenburg (24) has observed that 
pus contains a nucleo-proteid having the properties of a peroxidase 
and that its peroxidase activity is lost on boiling. Hence, by means 
of the phenolphthalin reagents we could readily distinguish between 
blood and pus. 
Similarly with regard to urine. Doctor Roberts and myself have 
found that only urine containing pus exhibits true peroxidase reac- 
tions. Such urines never oxidize an alkaline solution of phenolphtha- 
lin containing hydrogen peroxide unless they contain blood, and as 
already pointed out certain urines maj even contain blood and still not 
oxidize phenolphthalin in the presence of alkali and hydrogen perox- 
ide, on account of the presence of restraining (reducing) substances, 
and I myself have never encountered a normal urine that would show 
either true peroxidase reactions or that would induce the oxidation 
of an alkaline solution of phenolphthalin by hydrogen peroxide. 
