29 
oxidized so rapidly in alkaline solution by hydrogen peroxide under 
the influence of blood as a carrier, and that it is also oxidized in 
alkaline solution b}" blood alone, but more slowly, would seem to 
indicate either that in the alkali itself we have traces of hydrogen 
peroxide or that the blood pigment can function both as a peroxide 
and as an ox}^gen carrier. In support of the latter view it is worthy 
of note that the oxidation of phenolphthalin by blood occurs in solu- 
tions of X/10 sodium h^nlroxide which have been prepared b}^ the 
action of sodium amalgam upon water and in which it seems fair to 
assume that no peroxide compounds would be present; and in no 
case did the N/10 solution of sodium hydroxide employed in this and 
the other investigations give any test for h}"drogen peroxide with 
the titanic acid reagent. 
In alkaline solutions of phenolphthalin containing hydrogen 
peroxide the principal function of the blood seems to be that of an 
oxygen carrier, similar in its action to finely divided platinum. 
DELICACY OF THE PHENOLPHTHALIN BLOOD TEST. 
As already pointed out, TJtz (191) regards the phenolphthalin- 
hydrogen peroxide reagent as a more delicate reagent than either 
guaiacum (van Deen) or aloin (Rossel). Quite recently Delearde 
and A. Benoit (16) have been able to recognize one part of blood 
diluted with 1,000,000 parts of water b}^ means of Meyer’s reagent 
and hydrogen peroxide. In my opinion, the delicac}^ of the phenol- 
plithalin-h^^drogen peroxide test is even greater than that observed 
by the latter authors, as may be seen from the following observa- 
tions : 
Fresh solutions of human blood were prepared of the following 
concentrations : 
(1) 0.0038 gram of blood was dissolved in distilled water and made up to 100 c. c. 
(2) 10 c. c. of solution (1) were made up to 100 c. c. with distilled water. 
(3) 10 c. c. of solution (2) were made up to 100 c. c. with distilled water. 
(4) 10 c. c. of solution (3) were made up to 100 c. c. with distilled water. 
Hence, 1 c. c. of solutions (1), (2), (3), and (4) contained the fol- 
lowing quantities of blood, respective^: 
Solution. 
Quantity of blood 
in 1 c. c., gram. 
Number (1) 
Number (2) 
Number (3) 
Number (4) 
0. 000038 
. 0000038 
. 00000038 
. 000000038 
