40 
Similar tests were made on these specimens of milk after boiling, 
using the same quantities of milk and of the reagent as were employed 
in testing the raw specimens. At the end of three minutes the 
solutions showed the following colors: 
(1) Red. 
(2) Deep red. . 
(3) Pink. 
(4) Trace of pink. 
(5) Trace of pink. 
The conduct of these milks, raw and boiled, was also tested towards 
alkaline phenolphthalin alone, using 1 drop of each specimen of milk 
and 2 c. c. of the reagent. After standing all night at the ordinary 
temperature the solutions showed the following colors: 
Raw. 
(1) Purplish.red. 
(2) Deep purplish red. 
(3) Pink. 
(4) Trace of pink. 
(5) Trace of pink. 
Boiled. 
Purplish red. 
Deep purplish red. 
Pink. 
Trace of pink. 
Trace of pink. 
Milk (3) was distinctly darker in color than (4) and (5). The 
colors of (1) and (2) were compared in the Duboscq colorimeter with 
the following results: 
Readings on colorimeter scale. 
Raw. Boiled. 
(1) 4.0 4.0 
(2) 2.0 1.8 
These results signify, of course, that approximate!}^ twice as much 
phenolphthalein had been produced in (2) as in (1), and in this con- 
nection it is interesting to note that (2) contained approximately 
twice as much blood as (1) in the original solution, viz: 
(1) 0.0024 gram. 
(2) 0.0051 gram. 
Hence by means of phenolphthalin we are not only able to detect 
very small amounts of blood in milk, but also to determine the 
relative amounts thereof in several samples by colorimetric com- 
parison. These 5 specimens of human milk, raw and boiled, were 
also tested for blood by the benzidin test, using 1 drop of milk, 0.5 
c. c. of distilled water, 3 drops of acetic acid, 0.5 c. c. of benzidin 
solution, and 0.5 c. c. of a 3 per cent solution of hydrogen peroxide, 
with the following results: 
Raw. 
(1) Light bluish green. 
(2) Deep indigo blue. 
(3) Colorless. 
(4) Colorless. 
(5) Colorless. 
Boiled. 
Decided blue. 
Deep indigo blue. 
Colorless. 
Colorless. 
Colorless. 
