Dr. S. M. Babcock of Madison, Wis.
HOW TO TEST MILK
Milk may be adulterated or decreased in value either by skimming or by watering. In either case the percentage of the most valuable constituent, the butter-fat, is diminished. It is upon this fact that the most practical test, the Babcock, is based.
Babcock test outfit
The Babcock Test.[[2]]—By treating a sample of milk with strong sulphuric acid the butter-fat is liberated as an oil. By subjecting the mixture to centrifugal force the light butter oil is separated from the rest of the milk and the percentage can be easily determined. Centrifugal force had already been used in the Fjord Cream Test, but it remained for Dr. Babcock to work out the splendid practical and reliable test which bears his name and in which he has given to the world an invention of incalculable value.
A two-bottle machine
Sampling.—Whether it is new milk or skim milk or buttermilk or cream that is to be tested the first thing to observe is to take a truly representative sample. The liquid must be thoroughly mixed by pouring it several times from one vessel to another, or stirring vigorously.
It may not always be convenient to make a test immediately when the sample is taken. In the creamery where the milk is paid for according to its fat contents, samples are taken every day from every patron’s milk and it would take too much time for the butter maker to test all of these samples before they would spoil. A preservative, corrosive sublimate,—poisonous but all right for the purpose,—is therefore added and all the samples of one farmer’s milk for several days or a whole week are put together in one glass to be kept and tested at one time. This is called a composite test and has proven entirely satisfactory.