ANIMAL HEAT 



445 



The second part of the calorimeter consists of a closed system of tubes 

 tnd absorption vessels through which the air is kept moving under the action 

 )f a blower and thus kept in a respirable condition. As the air leaves the 

 :hambeMt passes through two absorption vessels by which the water and 

 :arbon dioxid are successively absorbed and collected by sulphuric acid and 

 >oda^lime respectively. The air then passes through an additional sul- 

 phuric-acid vessel which absorbs any water carried from the soda-lime vessel 

 Dy the air and so back into the chamber. By weighing these absorbing 

 vessels before and after the experiment the amount of water and carbon 

 iioxid are readily determined. The oxygen of the air of the chamber that 

 s utilized for respiration purposes is restored by the admission of oxygen 

 :rom a cylinder in necessary amounts by special automatic devices. The 

 imount of oxygen entering the chamber is determined by weighing the 

 :ylinder before and after the experiment. The loss in weight shows the 

 oxygen consumed. Of course, the air of the chamber must be analyzed 

 o correct certain errors that may piossibly arise. 



With the calorimeters described in the foregoing paragraphs it is pos- 

 sible not only to determine directly, but also indirectly, from the amounts 

 protein, fat, and carbohydrate metabolized (calculated from the C,H,O, 

 ind N eliminated and O absorbed) the heat produced and dissipated each 

 iay under a great variety of conditions e.g., when the subject is fasting or 

 iving on the customary diet; when resting or doing a fair days work; when 

 in health or in disease, etc. 



i. During Fasting. In an experiment extending over a fasting period 

 of seven days' duration, recorded at length by Benedict, the heat was 

 determined directly, and also indirectly, from the materials metabolized. 

 Some of the results of this experiment are shown in the following tables: 



METABOLISM OF S. A. B. DURING A SEVEN-DAY FAST 



Many similar experiments have been made by Benedict and by o her* witi 

 different forms of apparatus. As an average result it may be state 

 in the fasting condition and doing light work there is an average , heat-. 

 tion of 3 t or 32 calories for each kilogram of body-weigh , thus making a 



the food 



ary diet, and ' 

 condition, the amount of heat produced and liberated 



nee, 



