SOURCES OF VITAL HEAT. 409 



He left the hospital, became partially paralyzed, and then devel- 

 oped fever, his temperature rising to 42 and 45 C.; May 1, at 

 night, it was 44 C.; May 2, in the morning, 37 C.; May 4, 2 A. M., 

 44 C. He had chills, and was treated for malaria. After May 17, 

 he had no rise of temperature. He was a wreck from alcohol. 



Heat-unit. The standard of measure of heat is the heat-unit 

 or calorie. It is the amount necessary to raise the temperature of 

 1 gram of water 1 C. This is called the small calorie, to distin- 

 guish it from the kilocalorie or kilogramdegree, which is equal to 

 1000 small calories, and represents the amount of heat necessary 

 to raise the temperature of 1 kilogram (liter) 1 degree C. It is 

 estimated that an average man produces daily from 2200 to 3000 

 kilocalories, which is about 100 kilocalories per hour. During 

 active exercise this amount is greatly increased, even to the amount 

 of 3000 kilocalories hourly, while during sleep it may be but 40 

 kilocalories. 



Sources of Vital Heat. The sources from which the heat 

 of the body is derived are numerous. Among them are : 



1. The Oxidation of the Food-stuffs. The oxidation of carbohy- 

 drates and fats results in the production of CO 2 by the oxidation of 

 the carbon, and of H 2 O by that of the hydrogen ; while from the 

 proteids are formed by the same process CO 2 , H 2 O, urea, and certain 

 extractives. This oxidation may take place with the result of pro- 

 ducing heat, or it may result in the production of some other form 

 of energy, as the contraction of muscles ; but whatever form it may 

 take, the ultimate products of oxidation are the same. Fat burned 

 outside the body and fat burned (oxidized) inside the body will 

 produce the same amount of heat. If, therefore, the chemical 

 composition of the food-stuffs is known, and also that of the 

 products of their oxidation when eliminated from the body, it is a 

 simple matter to calculate the heat-value of any food. Chemists 

 have ascertained that the oxidation of 1 Gm. of carbon to CO 2 

 produces 8080 calories ; and of the same amount of hydrogen to 

 H 2 O, 34,460 calories. The oxidation of 1 gram of carbohydrate, 

 as starch, to CO 2 and H 2 O results in the production of 41 16 calories, 

 and of fat, 9312 calories. Carbohydrates and fats are completely 

 oxidized in the body, not with the direct and immediate production 

 of CO 2 and H 2 O ; but though there are many intermediate stages, 

 still the ultimate results are the same as when the oxidation takes 

 place outside the body. 



Proteids, on the other hand, are not completely oxidized in the 

 body, for, as we have seen, the products of their oxidation are 

 mainly CO 2 , H 2 O, and urea ; but urea is still further oxidizable. 

 This oxidation does not occur in the body, as urea is eliminated 

 as such ; hence in estimating the heat-value of proteids we must 

 deduct that of urea. The complete oxidation of 1 gram of proteid 

 to CO 2 and H 2 O produces 5778 calories, but we must deduct from 

 this the heat- value of the urea produced in their oxidation. One 



