30 
Tubes were prepared containing 1 c. c. of each of these sokitions, 
and to each tube there was then added 2 c. c. of the reagent, and a 
control tube prepared containing 1 c. c. of distilled water and 2 c. c. 
of the reagent. These tubes were allowed to stand five minutes at 
room temperature, and at the end of this time the tubes showed the 
following colors: 
i 
I Tube, 
Qnan dty of blood , 
gram. 
Color. 1 
i Control 
Xone, 
Trace of pink. f 
i XuinberO) ' 
aooooss 
Deep purplish red. j 
Xnmber cn 
.a»oa5s 
Purphsh re*i. ! 
1 Xumber (3) ! 
.0000003S 
Pink. j‘ 
} XtLmber(4) i 
-OOOOOOOS 
Light pink. | 
The color shown by (.3) was much deeper than that shown by the 
control tube, and while the color shovui by tube (4) was only light 
pink it was decidedly more colored than the control, the difference 
in color being recognized independently by two persons. The colors 
of these solutions were then compared in the Duboscq colorimeter 
with a standard solution of phenolphthalein containing 0.00031Sgram 
of phenolphthalein in 1 c. c. alcohol, 0.42 c. c. X 10 sodium hydroxide, 
and 1.5S c. c. water, when the following readings were obtained in 
divisions on the scale of the colorimeter, the test in all cases being 
put at o divisions on the scale: 
i Test. 
i' 
Eeading. 
Standard. 
j Control 
5 \ 
Xot measurable. 
1 Number (1) ' 
] o 
aa 
Xumber (2). . . J 
1 ^ 
1.2. 
Xumber (3) | 
' 5 ' 
a 2 . 
Xumber ' 
5 
Xot measurable. 
It is evident from these results that, as actually measured in the 
colorimeter, we are able to detect the oxidizing power of 0.0000003S 
gram of blood acting at a total dilution of 3 c. c., or approximately 1 
part of blood to S, 000, 000 parts of water: and that by direct com- 
parison of the colors produced, with the unaided eye we can detect 
the oxidizing effect of even one-tenth of this amount, viz, 0.00000003S 
gram at a total dilution of 3 c. c.. or approximately 1 part of blood in 
80.000. 000 parts of water. The thhd dilution, or 1 part of blood to 
8.000. 000. closely corresponds to the minimum amount of blood 
found by Delearde and A. Benoit (16) to produce a recognizable 
color with the reagent, provided that we take into account the total 
volume of fluid of all the reacting substances. 
