12 
In addition to these, a large number of aromatic amines, mono-, 
di-, and tri-acid phenols and aromatic acids have been studied by 
Adler (2). 
Similarly a considerable number of oxidizing agents of the general 
t}^e of hydrogen peroxide have been studied with regard to their 
general applicability to the Schoenbein-Van Deen blood test. Cliief 
among these are old oil of tui’]3entine (the so-called ozonized oil of 
turpentine) and hydrogen peroxide itself. Other observers have em- 
ployed ozonized ether and other ozonized ethers and oils. Battelli 
and Stern (13) have used ethyl peroxide, and Ladendorf (96) has 
recommended oil of eucalyptus as preferable to oil of turpentine. 
In a private communication Dr. A. S. Loevenhart informs me that 
iodoso-benzoic acid oxidizes phenolphthalin under the influence of 
blood. 
GEXERAL THEORY OF THE REACTIOX. 
According to Schoenbein (151), blood acts upon hydrogen peroxide 
and other antozonids after the manner of platinum, in that it converts 
the antozonid into an ozonid, or into a compound in which the oxygen 
exists in the active condition, viz, in the form of ozone, and that the 
ozone of the ozonid. then converts the guaiacum into a similar ozonid 
compound wliich is blue in color. Schmidt (144) even went so far 
as to believe that he had shown that blood itself contains ozone, for 
the reason that it blues guaiacum in the absence of ozonized oil of 
turpentine. Schuster (165), however, was unable to confirm Schmidt’s 
observation that blood alone blues guaiacum, and it is now known 
that old tinctures of guaiacum, in contradistinction to the fresh tinc- 
tures of the resin, contain peroxide compounds, which, under the 
influence of oxygen-carriers, like blood, produce guaiacum blue. 
Therefore, in all such cases, it is the old guaiacum and not the blood 
itself which supplies the oxygen necessary for this reaction. Schuster 
(165) was also of the opinion that the bluing of guaiacum by various 
substances was perhaps partly the result of a mechanical action, 
since he was able to blue it by shaking together a mixture containing 
the tincture, turpentine, and fine glass fragments. On the other 
hand, he found a simple oil emulsion to be inactive. He was of the 
opinion, therefore, that the reaction was not sufficiently well under- 
stood to justify the complete acceptance of Schoenbein’s theory of 
the process. 
It has been held by some observers that the activity of blood as an 
oxygen carrier depends upon the presence of an oxidase or peroxidase. 
Thus, in their recent study of the oxidation of phenolphthalin by 
blood, Delearde and A. Benoit (16) arrived at the conclusion that 
the blood plays the part of an indirect oxidizing ferment (peroxidase). 
Buckmaster (30) regards the oxidation as due to a pseudo-peroxi- 
