twenty or twenty-four hours, when the ferment will be found thick and in the proper condition for mixing with the cream or milk to be ripened.

How to use the Ferment.-First bring the cream or milk in the vat to a temperature of 66° to 70° Fahrenheit, when the ferment is to be thoroughly mixed with the cream or milk in the proportion of 2 per cent of the ferment to the amount of cream or milk to be ripened. Remove one or two inches of the top of the ferment, which is not desirable to use, and strain the rest through a fine strainer or hair sieve into the milk or cream. The finer the ferment is broken up the more effective its operation will be. After the cream or milk and ferment are well stirred and mixed at the above temperature, the vat must be closed and allowed to remain undisturbed until the cream is ripened, requiring from twenty to twenty-four hours for the operation; the cream when ripe will be found thick, mildly acid, and in the proper chemical condition, requiring only to be cooled to the proper temperature for churning.

Churning. The best temperature for churning depends so much upon circumstances that the range is very wide, from 55° to 68° Fahrenheit. The richer the cream in butter-fat the colder the temperature should be, and the more milk the cream contains the higher the churning temperature should be. After the cream or milk and ferment are mixed, no more stirring is admissible, as any agitation of the cream afterwards retards the ripening process.

Butter by Shallow-pan Creaming.-Raise the cream in a temperature of about 60° F.; avoid as much as possible skimming milk in with the cream; ripen at about 65° F.; churn at 60° to 62°. Free the granules of butter from the buttermilk by washing in water, temperature about 55°. Salt, I oz. to 1 lb. of butter.

Butter by Deep Cold Setting and Cooley System.-Raise the cream in ice-water; milk may be skimmed in with the cream or not as desired; with the Cooley cream a very considerable portion of milk added to the cream will produce no bad effects. Ripen at a temperature of 68° by adding lactive ferment; churn at temperature of 58° to 65°;

wash the granules in water, temperature 50° to 55°, and

salt as above.

Butter from Separator Cream.—Cool the cream from separator to 66° to 68°, add lactive ferment, and churn at 55° to 58°, according to the percentage of butter-fat in the cream. The cream should be cooled after ripening so that the temperature of the cream will register not over 55°. This cooling requires time and patience, but will be rewarded with solid granules. Wash in water at 50° to 52°. Salt, I oz. to I lb. of butter.

Good butter should not contain more than 16% of water (and may contain as little as 8%) when properly worked. It is sufficiently worked when it presents a delicate elasticity to the touch, and when broken should show a perfect uniformity of grain and color.

THE ALKALINE TABLET TEST OF ACIDITY IN MILK OR CREAM.*

By Prof. E. H. FARRINGTON, of Wisconsin Dairy School.

Since this test was first described by the author, a number of changes have been made in the way of using it.

Reliable results are now obtained with less and simpler apparatus than when the test was originally published. At the present time it is used for two purposes.

First. For testing the acidity of milk. To detect those lots which are apparently sweet, but too nearly sour for pasteurizing, for retailing, or for making the best butter or cheese.

Second. For testing the acidity of each lot of cream during its ripening, to trace the progress of its souring, and to show whether the fermentations should be hastened or checked in order to have the cream in a certain acid condition at a given time and ready for churning.

In addition to the tablets, the only apparatus necessary for testing the acidity of either milk or cream is a common white teacup, a 4, 6 or 8 oz. bottle, and a No. 10 brass cartridge-shell or similar measure. The testing solution is

* For a more detailed discussion of the alkaline tablet test, see Farrington-Woll, "Testing Milk and its Products," Sixth Ed., pp. 109-120.

The

prepared by dissolving one tablet in one ounce of water. This is the standard. Four ounces of the tablet solution are made by filling a four-ounce bottle with water and adding to it four tablets. The No. 10 shell is filled with the milk or cream to be tested. This measured quantity is poured into a white cup. The same measure is then filled with the tablet solution and this is poured into the cup. two liquids are thoroughly mixed and the color of the mixture is noted. If there is no change of color, another measure of tablet solution is added. This is continued until the sample which is being tested becomes of a pink color. As soon as the pink color is obtained no more tablet solution is added. The per cent of acid in the sample tested is found from the number of measures of tablet solution it is necessary to add to one measure of the sample in order to produce the pink color. Each measure of tablet solution represents one tenth of one per cent acid.

A more exact testing of acidity can be made by using a 17.6-cc. pipette for measuring the milk or cream to be tested and a 100-cc. graduated cylinder for the tablet solution.

Five tablets are dissolved in 97 cc. of water in the cylinder, and this solution is gradually poured into the 17.6 cc. of milk or cream in a white cup. When sufficient tablet solution has been added to produce the pink color in the sample tested, the operator observes on the scale of the graduated cylinder the number of cc. tablet solution used. Each cc. of this tablet solution is equal to 0.0090 gr. lactic acid, and when 17.6 cc. of a sample is tested, each cc. of the tablet solution is equal to .or per cent acid in the sample.

Milk does not smell or taste sour until it contains about three-tenths of one per cent acid. It has been found, however, that milk containing over two tenths per cent acid cannot be safely pasteurized, because such milk sours very soon. These tablets supply a quick means of selecting the sweetest of different lots of sweet milk, by showing which contain less than two tenths of one per cent acid.

Cream is often ripened so far that the quality of the butter is injured. The usual method of the butter-maker for testing the sourness of the cream is by the sense of smell and taste. A tablet test shows exactly what per cent of acid each lot of cream contains, so that the butter-maker is better able to manufacture a uniform grade of butter by ripening his cream to the same point before it is churned. Sweet cream contains about 0.15% acid. Cream has reached the proper point for churning when it contains about sixtenths per cent acid. As the souring of cream is largely influenced by the temperature at which it is held, the butter-maker is able to know from an acid test of the cream whether it should be warmed or cooled in order to have it ready for churning at a given time and just sour enough for making butter of good flavor (see page 2756).

DIRECTIONS FOR THE USE OF MANNS' TEST FOR ASCERTAINING THE ACIDITY OF

CREAM.

1. Stir the cream thoroughly; insert small end of pipette in cream and draw until nearly full; then put the finger over upper end of pipette and allow cream to escape slowly (by admitting air) until mark on neck of pipette is reached. Transfer to a tumbler, rinse the pipette three times with lukewarm water, adding the rinsing water to the cream in the tumbler. Now add to contents of the tumbler three drops of the solution marked "Indicator" (phenolphtalein). 2. Fill the burette up to the o mark with the solution marked " Neutralizer" (alkali solution).

3. While constantly stirring the cream with the glass rod, allow the liquid to flow from the burette into the tumbler until the entire contents of the tumbler shows a pink tinge. Stop adding the solution from the burette the moment the color is permanent.

4. Read the level of the liquid remaining in the burette. The reading shows the amount of acid present.

The experience of those using the test indicates tha where the acidity of the cream is right, to secure the best results in yield and flavor of butter, from 38 to 42 cc. of the neutralizer will be required for the test. It is a simple

matter for each butter maker to learn by experiment the exact degree of acidity and churning temperature suited to the best results, and with these as standards reduce the process of butter-making to a certainty. By testing his cream in the afternoon the butter-maker will be able to set it to ripen at such a temperature that it will show the proper acidity for churning next morning.

In testing the milk for cheese-making the same directions are to be followed, excepting that a much less acid condition is required; probably 15-20 cc. will give the best results. The whole numbers are cubic centimeters; the intermediate divisions are fractions of a cubic centimeter.

Precautions in Using the Test.-The solution marked "Neu. tralizer" is prepared of a certain strength. It is essentia! that this strength remain constant. Never let this solution stand without a stopper. Keep in glass or stoneware. PERCENTAGE COMPOSITION OF BUTTER. (KÖNIG.)

AVERAGE CHEMICAL COMPOSITION OF SWEET CREAM- AND SOUR CREAM-BUTTER.