Suppose a man is using two quarts of milk a day, and wishes to determine the amount of available nitrogen or tissue-building material and energy it contains. Under the old system he must get a book on food analysis, or send to Washington for a Government bulletin. If he does not understand the meaning of the terms and figures used, the tables would be useless to him until he goes to a chemist to have them explained. He is now ready to work out the nutritive value of his milk, and proceeds as follows:
First, he gets the number of cu cm in the milk, thus—952.8 (number cu cm in 1 quart) x 2 = 1905.6, number of cu cm in 2 quarts of milk. Second, he gets the weight of his milk in grams—1.032 (number grams in 1 cu cm of milk) x 1905.6 = 1966.57, number of grams in 2 quarts of milk.
He now turns to a table of analysis which tells him that milk contains 3 per cent of protein, 3½ per cent of fat, and 4½ per cent of sugar. As the amount of nitrogen in milk is approximately one-sixth of its entire protein, he would now get 16 per cent of the 3 per cent (.16 x .03 = .0048), which is the percentage of nitrogen contained in milk.
His next step would be—1966.57 (number grams in 2 quarts of milk) x .0048 = 9.44, the number of grams of nitrogen in 2 quarts of milk.
I will not explain the way in which the energy would have to be figured, but will merely give the arithmetical processes by which the result is obtained:
3 × 4.1 = 12.3
3.5 × 9.3 = 32.55
4.5 × 4.1 = 18.45
12.3 + 32.55 + 18.45 = 63.30
1966.57 × 63.30 = 124483.88
124483.88 ÷ 100 = 1244, the No. of calories or energy (heat units) contained in two quarts of milk.
THE NEW OR "VIENO" SYSTEM
Derivation of the word Vieno