46 Influence of Inanition on Metabolism. 



the period from 10 p. m. to 1 a. m. the correction is positive. It is important 

 to note that no matter what error affects this correction, it is a compensating 

 one and hence it does not affect the measurement of the heat elimination for 

 the 2-1 hours. It affects only the two periods to which the corrections are 

 applied. 



Correction for the heat of vaporization of water. A very considerable pro- 

 portion of the total heat given off from the body, especially during rest, is 

 used for the vaporization of water from the lungs and skin. The amount of 

 water thus vaporized equals the total amount in the outgoing air plus the gain 

 or loss of water vapor in the residual air from the preceding period. For the 

 want of a more accurate factor for the heat of vaporization of 1 gram of water 

 at the temperature of the calorimeter we have used the factor 0.592, based on 

 Begnault's work. 



Summary of calorimetric measurements. The various corrections mentioned 

 above to be applied to the heat measured by the calorimeter are given in table 

 14, the total corrected heat eliminated being recorded in column h. 



Total Heat Production. 



The simple measurement of heat lost by the body is not sufficient for the 

 proper interpretation of the processes of metabolism. Since metabolism and 

 heat production rather than heat elimination go hand in hand, it is of vital 

 importance to distinguish between heat production and heat elimination; and 

 for accurate measurements of heat production, knowledge of the fluctuations 

 in the store of heat in the body is absolutely essential. 



Changes in the residual heat in the body due to variation in body weight and 

 temperature. The body of the subject may be said to be a large reservoir 

 for heat and the quantity of heat thus stored in the body varies with every 

 period of the day. Even with constant body temperature there are noticeable 

 fluctuations in body-weight which involve considerable changes in the amount 

 of heat actually existing in the body. Similarly, differences in body temper- 

 ature cause fluctuations in the storage of heat. For example, if a subject 

 weighs 60 kilos and there is a rise of temperature of 1 C, this is practically 

 equivalent to the storage of 50 calories, since the specific heat of the body is 

 not far from 0.83. A corresponding fall of temperature is followed by a 

 corresponding loss from the store of heat. But even though the temperature 

 be constant, if the body loses 500 grams in weight, obviously 500 grams of 

 material have been cooled from the temperature of the body, 37 C, to the 

 temperature of the chamber, 20 C, and thus 7.1 calories of heat have been 

 given up which were not actually produced during the period. 



If the calorimeter chamber were provided with a weighing arrangement 

 whereby body-weights could be taken at the end of each experimental period, 

 part of the data for these corrections could be readily secured. Unfortunately, 



