Care should be taken not to run in too much silver nitrate. If too much silver nitrate is used, the color will be a dull brick-red, and incorrect results will be obtained. An — normal solution of silver nitrate, which is accurate enough for the purpose, may be made by dissolving 171/2 grams of silver nitrate in 200 cc. of water and then making the solution up to 1000 cc. or one liter.

Over-run in butter-making (Pa. Sta. and U. S. Dept. Agric).

Over-run in butter is the amount of water, casein, and salt incorporated in the butter-fat in making butter. Creamery over-run, however, should always be computed from the number of pounds of butter-fat received and the pounds of butter sold.

The formula for calculating over-run in percentage is as follows :

Milk Tests Part 5 170

In a whole-milk creamery it is possible to obtain from 18 to 20 per cent over-run and have only 14 to 141/2 per cent moisture in the butter, while in a creamery where hand separator cream is received, 20 to 22 per cent over-run can be obtained. This is shown by the following two examples : —

Example :

10,000 pounds 4 per cent milk contains 400 pounds butter-fat.

10,000 pounds 4 per cent milk gives 1600 pounds 24+ per cent cream and 8400 pounds skim milk.

1,600 pounds of cream testing 24+ per cent contains 391.6 pounds butter-fat.

8400 pounds skim milk, loss (maximum) .1 per cent, is 8.4 pounds butter-fat.

1600 pounds cream less 391.6 pounds butter-fat, leaves 1208.4 pounds buttermilk.

1208.4 pounds buttermilk at .2 per cent loss is 2.4 pounds butter-fat, the loss in churning.

8.4 pounds butter-fat, loss in skim milk, and 2.4 pounds butter-fat, loss in buttermilk, gives 10.8 pounds butter-fat loss in both.

10.8 pounds butter-fat from 400 pounds butter-fat leaves 389.2 pounds of butter-fat to be churned into butter.

If 389.2 pounds butter-fat is churned into butter containing 14 per cent water and 4 per cent salt and casein, it will make 474.6 pounds of butter.

474.6 pounds less 400 pounds gives 74.6 pounds of butter, which is the over-run.

74.6 pounds of butter times 100 makes 7460, divided by 400 gives 18.6 per cent over-run.

Spoon-test for oleomargarin and renovated butter.

Place in a tablespoon a piece of the sample, about the size of a hickory-nut. Hold the spoon over the flame until the sample is melted, and stir frequently while melting. Then lower the spoon into the flame. Oleo and renovated butter will boil with a loud crackling noise, and there will be almost no foam on the surface of the sample. Genuine butter will boil quietly and the surface will be covered with foam.

The test for moisture in cheese (Ross).

Obtain a representative sample of cheese as directed in the test for fat in cheese. Then in a flat-bottom dish at least three inches in diameter weigh out 3 grams of cheese. If no glass dish is at hand, a tea saucer will answer the purpose. Heat the sample in a water oven at the temperature of boiling water for eight hours. Cool the dish, weigh and divide the loss in weight by the three grams of cheese taken. Multiply the quotient by 100. This quotient is the percentage of moisture in the cheese. Care should be taken to place the cheese in the dish in as thin a layer as possible. This will make it easier for the moisture of the cheese to escape.

The Babcock test for fat in cheese (Ross).

Secure a representative sample of the cheese. This is best done by means of a cheese trier, taking a plug from the center of the cheese one-half way between the center and the outside of the cheese and one very near the outside of the cheese. Using a knife, mince these three plugs as fine as possible and mix them thoroughly. After the sample is minced very fine and thoroughly mixed, weigh out on a set of cream balances in a cream bottle 4 grams of the cheese. Add 5 cc. of warm water and shake thoroughly for one or two minutes. Then make the sample up to approximately 18 grams by the addition of water, and add 17.5 cc. sulfuric acid. After the acid is added, shake the sample thoroughly for from two to three minutes. The purpose of this shaking is to dissolve all of the cheese curd. If this is not done, the fat column will be cloudy. Then place the bottles in the machine and proceed with the test in the ordinary way.