. Cyclopedia of farm animals. Domestic animals; Animal products. Fig. 167. Milk jar for holding samples. to the base of the neck. It is then whirled two minutes and more hot water is carefully added until the fat rises in the neck so that it is opposite the graduations. The sample is then whirled one min- ute, to insure collecting as much fat as possible in the neck. While the fat is still warm, its percentage is ascertained by reading the marks at its upper and lower levels and taking the difference between them. The cost of a small complete outfit for testing milk is six to ten dollars, and
. Cyclopedia of farm animals. Domestic animals; Animal products. Fig. 167. Milk jar for holding samples. to the base of the neck. It is then whirled two minutes and more hot water is carefully added until the fat rises in the neck so that it is opposite the graduations. The sample is then whirled one min- ute, to insure collecting as much fat as possible in the neck. While the fat is still warm, its percentage is ascertained by reading the marks at its upper and lower levels and taking the difference between them. The cost of a small complete outfit for testing milk is six to ten dollars, and one may be purchased from almost any dairy supply house. An outfit complete is shown in Fig. 168. The Gerber method of testing milk for fat is used extensively in Germany and Denmark, and is found occasionally in this country. It differs but little from the Beimling method. This test depends on the same principles as the Babcock test. A smaller quantity of milk is used for the sample, and amyl alcohol is added besides sulfuric acid. The amyl alcohol has the effect of assisting to a clear sepa- ration of the fat. Test for formaldehyde. Formaldehyde is sometimes used as a preserva- tive of milk, although this is unlawful in most states. The general objections to preservatives obtain in this case, and a further objection to formaldehyde is that it renders the casein in milk insoluble, and, therefore, less digestible. Hehner's test for formaldehyde is exceedingly delicate. It is sensitive for one part of formaldehyde to two hun- dred thousand parts of milk. This test is as follows : To a few cubic centimeters of the suspected milk add a few cubic centimeters of concentrated com- mercial sulfuric acid, and pour this in carefully, so that it will follow the side of the glass container to the bottom, not mixing with the milk, but form- ing a distinct layer under it. If a violet color is noticed where the two liquids come together, for- maldehyde is indicated; otherwise, there will be
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