EXERCISE NUMBER II STANDARDIZATION Cream and milk to standardize will be furnished. Test both by the Babcock method and report the result to the instructor, who will assign a definite percentage of fat for the standardized mixture. After standardizing, test a sample of the standardized mixture by the Babcock method to test the accuracy of your work. Report all calculations and results on opposite page. EXERCISE II REPORT EXERCISE NUMBER III TESTING ICE CREAM FOR FAT Ice cream cannot be tested for fat, by the Babcock test, as milk, because the acid chars the sugar, which interferes with the reading. Various methods of testing ice cream, so as to overcome this disadvantage have been devised. A few of the simpler ones follow. Test a sample of ice cream by each of the following methods and report results on the opposite page. Method of Prof. H. E. Ross: Mix equal parts by weight of melted ice cream and water. Weigh into a 9 gram 50% cream bottle 9 grams of the mixture. Add 17.5 cc. of glacial acetic acid. Shake for two to three minutes. Next add 15 cc. of sulphuric acid such as is used for the Babcock test. Shake for one minute and proceed as in the ordinary Babcock test. Multiply the reading by two. Method of J. P. Dawson: Weigh 18 grams of melted ice cream at a temperature of 70 degrees F. into a 30%, 9 inch cream test bottle. Add 8 cc. of glacial acetic acid, agitate gently for 2 minutes and add 10 cc. of Babcock sulphuric acid. Shake and centrifuge in the usual manner. Note: There appears to be no reason why one half the quantities of ice cream and acids may not be used in a 6 inch 9 gram 50% cream bottle. Method often used by the authors: Weigh 9 grams of melted ice cream into a 6 inch 50%, 9 gram cream bottle and add about 9 cc. of water. Add three quarters of an acid measure of glacial acetic acid and mix thoroughly. Next add two thirds of an acid measure of Babcock sulphuric acid. Shake till well mixed and centrifuge in the usual manner. EXERCISE III REPORT EXERCISE NUMBER IV EFFECT OF THE SALT AND ICE MIXTURE ON TEMPERATURE Make a brine one part salt to ten parts of water by weight. With part of this fill the can of a hand freezer two thirds full just as though it were an ice cream mix which you were going to freeze. Record the temperature of this brine. _Trial_ 1. Using a mixture of one pound of salt to 10 lbs. of crushed ice, try freezing the brine in the freezer can. Turn 10 minutes, keeping the freezer can well covered with the ice and salt mixture. Open and record the temperature of the brine in the can.