Used by Plum Valley Creamery, Waldorf to collect milk samples for testing. Used to test the butterfat content in various types of milk. Milk tester vials are used with the Babcock Centrifugal Milk Testing Machine which ascertains the percentage of fat in a sample of milk. The sample is placed in a standard glass vial which has a long, slender neck graduated on the outside. The vial is then placed in a centrifugal machine and the fat is driven out of the milk, its position in relation to the graduated scale indicating the percentage of it in the milk. Several vials may lie tested at once. The test is made by adding acid to a weighed quantity of milk and separating the watery portion from the liquid fat by centrifugal force. The percentage of fat is shown by the thickness of the layer of liquid fat as measured in divisions of the graduated neck of the test-bottle.
