666 
requires intelligence and careful manipulation. 'With the possible 
exception of infant feeding, it would perhaps be better and cheaper 
to pasteurize the milk in bulk under competent supervision instead 
of leaving it to the usual carelessness of cooks, who can not be expected 
to master the technic nor appreciate the difficulties. Imperfect pas- 
teurization may be worse than none, for it may result only in further 
contamination of the milk. 
Milk pasteurized in the home is commonly heated too high and 
not rapidly cooled. 
The most iDractical home pasteurizer is that devised by Freeman.® 
The following experiments, made in the Hygiene Laboratory, with 
Freeman’s pasteurizer show its efficiency: 
Test No. A with Freeman’s Pasteurizer. 
Temperature of milk, 9° C. 
Temperature of water in jacket, 25° C. 
Milk introduced into boiling water and removed from the fire. 
Milk temperature — ® C. 
Five minutes after immersion in boiling water 47. 5 
Ten minutes after immersion in boiling water 63 
Fifteen minutes after immersion in boiling water 67. 4 
Twenty minutes after immersion in boiling water 68. 8 
Twenty-five minutes after immersion in boiling water 68. 9 
Twenty-eight minutes after immersion in boiling water 68. 9 
Whole time, twenty-eight minutes. 
Above 67° C. for thirteen minutes. 
Took fifteen minutes in running tap water, at 22° C., to cool milk to 30° C. 
The results follow: 
Bacteria per cubic cen- 
timeter. 6 
Raw milk. 
i 
[ After pas- 
j teurization. 
Milk from — 
Dflirv I .. 
34,600,000 
1.050.000 
80,000 
2.200.000 
2,100,000 
1.900.000 
2. 400.000 
2,000,000 
300 
50 
400 
200 
1,200 
None. 
600 
450 
Dairy F .. 
Dairy L 
Dairy M 
Dairy X 
Dairy 0 
Dairy P 
Dairy Q. 
“Freeman, Rowland G. : “Low temperature pasteurization of milk at about 68° C. 
(155° F.).” Arch, oi Fed., 1896. 
“ Colonies on agar plates after twenty-four hours’ incubation at 37° C. 
