39 THH AMERICAN MONTHLY (far 
erto proposed in this direction. In investigating plant- 
tissues for tannin, the substance is put ina test tube or 
watch glass and the reagent poured over it until it iscom- 
_ pletely covered, and in this condition it is set aside for 
from 38 to 4hours, At the end of this time the reagent 
is poured off and the material is thoroughly washed with 
water. It can now be placed under the microscope, and 
the cells containing tannin will be found to be stained 
from brown to black, according to the amount of tannin 
present. The reagent is prepared as follows: Dissolve 
2 gms. copper sulphate in distilled water, and add ammo- 
nia water until the precipitate at first formed is again ta- 
ken up. Distilled water is then added until the solution 
measures 100 ccm.—WNational Druggist. 
ADVANTAGES AND LIMITATIONS oF STERILIZING AND 
PasTEURIZING MiLk.—Dr. A. D. Blackader of Montreal. 
Milk obtained under unfavorable conditions and kept at a 
rather high temperature contained many bacteria, and in 
addition their spores and toxins. According to our pres- 
ent knowledge, all forms of bacteria are undesirable in 
dninfant’s food. It had been shown that 99.8 per cent of 
the bacteria could be destroyed by pasteurization. The 
older the milk was the more difficult it was to pasteurize 
it. Pasteurization at 70° C. destroyed the vast majority 
of the forms liable to produce extensive and rapid change 
in the quality of the milk. It was necessary in most in- 
stances to maintain the pasteurized milk at a low tem- 
perature in order to preserve it from further change. 
However, the same could be said of milk heated to 100° 
C. Milk exposed to 60° C. or 140° F. had ninety-six to 
ninety-nine per cent of its bacteria destroyed. Russell had 
found that when milk was heated in tubes to 140° F. tu- 
bercle bacilli were not entirely killed because the little 
pellicle which formed on the surface of the milk protect- 
ed the bacilli to some extent. If this pellicle was broken 
