COLORADO EXPERIMENT STATION 
5 
MILK TESTING. 
The method of operating the Babcock test when determining the 
amount of fat in milk, is here given in brief outline by steps : 
1. Mix thoroughly sample of milk which is at 65 degrees to 70 
degrees F. 
2. Fill pipette to mark with milk at once. 
3. Run milk into test bottle from pipette. 
4. Fill acid measure to mark with acid and pour into test bottle 
5. (1) Mix milk and acid thoroughly by rotary motion; (2) 
let stand one to three minutes; (3) mix again. 
6. Whirl four minutes at proper speed. 
7. (1) Add water up to neck of bottle of 170 degrees F., whirl 
two minutes; (2) add 170 degrees F. water to within the two or three 
percent mark of top, and whirl one minute. 
8. Read results at temperature of 120 degrees to 130 degrees F. 
The sampling of milk is the most important operation of the test. 
Unless the sample is representative of the milk from which it is taken, 
the result of the test cannot be correct. Thorough mixing before taking 
a sample or a test from a sample, is absolutely necessary and always 
the first step toward accurate results in testing. Pouring from one ves¬ 
sel to another is the best method of mixing. 
Care of Milk Samples .—Samples of milk should be placed in air¬ 
tight receiving jars, if the sample is to be left any length of time before 
testing. Tight sealing prevents evaporation. Should evaporation take 
place, the per cent of fat increases causing inaccurate tests. 
Milk samples should not be permitted to sour before testing, as 
souring causes lumps of curd to form which require extra care in dis¬ 
solving before testing. Souring may be prevented by keeping in a cool 
place or by use of some preservative, as formaldehyde or corrosive 
sublimate. When preservatives are added the sample should be shaken 
gently to insure mixing. One corrosive sublimate tablet will preserve 
one pint of milk for more than a week. 
Composite Samples .—Composite samples of milk or skim milk are 
taken the same as for cream, and the tests run according to directions 
given for whole or skim milk. 
Method of Making the Test 
Samples in good condition may be brought to a temperature of 
65 to 70 degrees F., thoroughly mixled, and the test taken at once, 
after thorough mixing and pouring. Samples that are sour or lumpy 
must be brought to a temperature of no degrees F. before mixing is 
attempted. 
All tests should be made in duplicate so that one test will serve 
as a check on the other for accurate work. If both tests of a duplicate 
are not alike, some mistake has been made. 
Measuring the Milk .—Milk is measured by the use of the milk 
pipette which holds, when filled to the mark on the stem, 17.6 c. c. 
