TESTS FOR HEATED MILK 373 
lower temperature the nuclei are not all stained above 60° C. The 
majoilty, however, are stained. 
Frost (1915) has pointed out some of the difficulties of the above 
method and devised a new one. 
Procedure. Add one part of aqueous methylene blue (7 gms. of 
Gruebler’s dry dye to 100 c.c. distilled water) to five parts of milk. 
This should be added slowly to prevent coagulation of the milk. Allow 
the stain to remain in contact with the milk for from fifteen to thirty 
minutes. Centrifuge and spread the sediment on a slide. This may 
be done by using the edge of another slide. Frost reports the following 
appearance in raw and pastcurized milk. Maw: The entire field is 
stained a light blue, the depth of the stain depending on the thickness 
of the film. In this blue background may be clear areas. These may 
be either leucocytes or fat globules. The leucocytes are practically 
always colorless. Heated Milk: Smears made from heated milk are not 
as deeply stained as those made from raw milk. The leucocytes are 
always more deeply stained than the background and appear as dark 
blue areas in a blue field. The background immediately about the 
leucocytes frequently shades off into the color of the background, thus 
forming a halo about them. Under the oil immersion objective the 
leucocytes are less regular in outline than those in raw milk. The nuclei 
are distinctly stained. 
Balaz’s Test for Boiled Milk. To 5 c.c. of the milk; add 2 c.c. of 
copper sulphate solution which contains 69.26 gms. of copper sulphate per 
liter. Shake and filter. Then, to five drops of the transparent filtrate 
add Adamkiewicz’s reagent (one part of sulphuric acid and two parts of 
acetic acid). Warm carefully without boiling, shake, and allow to 
stand for a while. The serum of the boiled milk remains colorless, while 
the raw milk shows a violet red color. Its greatest intensity occurs 
within ten or fifteen minutes. 
The “‘ Commission on Milk Standards Appointed by the New York 
Milk Committee ” has made a careful study of the production of safe 
milk. It is composed of the foremost authorities on the relation of 
milk to the public health. Realizing the lack of uniformity with regard 
to milk standards, the committee made the following recommendations. 
Chemical Standards. The following are proposed and represent 
those which are enforced in many cities and States. 
The Babcock test makes easily practicable the determination of 
fat and solids-not-fat in milk. Such examinations of milk can be readily 
adopted and executed by any health board laboratory at a very moderate 
expense. It is believed that such chemical standards as are suggested 
