Читать книгу Foods and Their Adulteration - Harvey Washington Wiley - Страница 15

—The term calorie is used to denote the amount of heat-forming material contained in one unit weight of a food product. The number given represents the number of degrees of temperature produced in a unit mass of water by the heat formed in burning the unit weight of food. The unit weights employed are usually as follows: Of the food product, one gram (15 grains); unit weight of water to be heated, one kilogram (2.2 pounds); unit increment of temperature, 1°C. (1.8°F.). The expression 4000 calories therefore means that if one gram of food substance in a dry state be burned the heat produced will raise one gram of water through a temperature of 4000°C., or the unit of water (one kilogram) through a temperature of 4°C. For convenience the calories are usually expressed as small calories, namely 4000, instead of large calories, namely 4. In this manual the expression in terms of small calories, that is, the temperature increase of one kilogram of water produced by burning one gram of substance, multiplied by 1000, will be uniformly employed.