698 
Journal of Agricultural Research 
Vol. XXXI, No. 7 
storage tank. The samples for bacterial count were suspended in 
the ice water, thus assuring that storage conditions would be the 
same for both the whole-milk sample and the separator can. At 
the end of 24 hours the separator can was taken out and the skim 
milk drawn off through the pet cock. Samples for bacterial count 
and fat test were taken. The cream was then drawn off and samples 
taken, all being 24 hours old. The average temperature at the 
beginning of the holding time was 38.44° F. At the end of 24 hours, 
when the skim milk and cream were drawn off, the average tem¬ 
perature was 45.88° F. The highest individual temperature was 
52° F. 
Bacterial counts and fat determinations were made the same as 
with the centrifugal separation samples. Twenty-five lots of milk 
were separated by this method. 
In no case was it found that the cream had a lower count than 
the whole milk. Two out of twenty-five samples of skim milk 
showed an increase in the bacterial count over that of the whole 
milk, while 23 samples gave a lower count, The average counts 
per cubic centimeter of the 25 samples were: Whole milk, 135,880; 
cream, 283,680; skim milk, 33,556. 
The average per cent increase in bacterial count of the cream over 
the whole milk was 160.86 per cent. The average fat percentages 
were: Whole milk, 4*208; cream, 20.52; skim milk, 1.22. 
The bacterial counts in the milk varied from 2,000 to 850,000 
per cubic centimeter. The majority of the samples gave a bacterial 
count of 100,000 or lower. The average percentage of butterfat 
was 4.208, but two samples were 5.0 per cent or higher. (See Tables 
V and VI.) 
Table V .—Range and average of bacterial counts and butterfat determinations in 
25 samples of whole milk and in the cream and skim milk separated from it by 
gravity 
Bacteria per cubic centi¬ 
meter 
Percentage of butter¬ 
fat 
Range 
Average 
Range 
Average 
25 samples whole milk.. 
25 samples cream_ _ 
2,000- 850,000 
5,000-1,700,000 
900- 180,000 
135,880 
283,680 
33,556 
3.0- 5.8 
14.0-24.0 
0 .5- 2.0 
4.208 
2a 52 
1.22 
25 samples skim milk____ 
Table VI .—Samples grouped according to bacterial count 
Bacteria per cubic centimeter 
10,000 
and . 
under 
10,001 
to 
25,000 
25,001 
to 
50,000 
j 
50,001 
to 
100,000 
1 
100,001 
to 
500.000 
500,001 
to 
1 ,000,000 
1 ,000,001 
and 
over 
Number of samples: 
Whole milk... 
4 
7 
4 
3 
4 
3 
0 
Cream..... 
1 
1 
7 
4 
7 
2 
3 
Skim milk..._ 
14 
4 
1 
4 
2 
0 
0 
