192 
Journal of Agricultural Research 
Vol. XXXI, No. 2 
Each unit was given an identification mark through the tests. 
The milk buckets were sterilized with steam after washing. The 
units were used but once a day during the greater period of the tests, 
which ran for six months. Three or four cows were milked with 
each unit at a milking. As far as possible, the same cows were milked 
during the entire period. Also, the machines were rotated—i. e., a 
machine which milked one group of cows one day was used to milk 
another group the next day and so on—so that each machine milked 
the same cows about an equal number of times. Cow’s teats and 
udders were washed and wiped with a clean cloth before milking. 
All cows chosen were normally low in udder bacteria. 
Results of the tests are shown in Tables I, II, and III. 
Table I. — Summary of bacterial counts obtained, in cold weather, on samples of 
milk drawn with machines sterilized by three different methods 
Method 
Number 
of sam¬ 
ples of 
Range in 
bacterial count 
Average 
bacterial 
count 
Samples of milk 
having a bacterial 
count of 10,000 
per c. c. or lower 
milk 
per c. c. 
per c. c. 
Number 
Per cent 
of total 
Heat_ 
239 
200 to 12,000 
900 to 25,000 
800 to 24,000 
2,390 
5,130 
5,250 
238 
99.6 
Chloride of lime_ 
241 
222 
92.1 
Salt and chloride of lime ___ _ 
241 
218^ 
90.5 
Table II. — Summary of bacterial counts obtained, in warm weather, on samples 
of milk drawn with machines sterilized by three different methods 
Method 
Number 
of sam¬ 
ples of 
milk 
Range in 
bacterial count 
Average 
bacterial 
count 
Samples of milk 
having a bacterial 
count of 10,000 
per c. c. or lower 
per c. c. 
per c. c. 
Number 
Per cent 
of total 
Heat_______ 
103 
600 to 6,700 
2,700 to 160,000 
2,100 to 45,000 
2,330 
17,300 
8,460 
103 
100.0 
Chloride of lime____ 
103 
59 
57.3 
Salt and chloride of lime___ 
104 
78 
75.0 
Table III. — Summary of all bacterial counts (Tables I and II combined) 
Method 
Number 
of sam¬ 
ples of 
milk 
Range in 
bacterial count 
per c. c. 
Average 
bacterial 
count 
per c. c. 
Samples of milk 
having a bacterial 
count of 10,000 
per c. c. or lower 
Number 
Per cent 
of total 
Heat___...... 
342 
200 to 12,000 
2,380 
341 
99.7 
Chloride of lime. ..... 
344 
900 to 160,000 
8,. 780 
281 
81.7 
Salt and chloride of lime. 
345 
800 to 45,000 
6,220 
296 
85.8 
