304 



MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



These latter values are shown in column k of the table. The corresponding amounts of water are 

 shown in column /. 



S.i far from claiming that these assumptions and the calculations based upon them arc correct, 

 we are persuaded that they must l>e more or les- erroneous; hut until determinations can he made 

 of the income and outgo of oxygen, we can hardly be warranted in making other assumptions 

 than those stated above. It is our present belief that the largest errors are in the figures for 

 water. The experimental data are recorded in such detail in previous tables that modifications 

 in the method of computing- the nitrogen, carbon, and hydrogen balance, and the gain or loss of 

 body material can be made at any time shorld results of later research indicate that such modi- 

 fications were desirable. 



Table XVII. — Gain or loss ofprott in i -V. ■ 6. :■" ),fat, and watt r. Metabolism experimt nt No. 1 '. 



Balance of energy. — The income and outgo of energy are shown in Table XVIII. The figures 

 for heats of combustion of food and unoxidized materials of feces and urine are taken from 

 Tables VI, VII, and VIII, respectively. The values in column d, heat of combustion of alcohol 

 eliminated, are derived from the corresponding values in the fifth column of Table XIV by mul- 

 tiplying the total alcohol unoxidized, as there given, by the heat of combustion per gram. T.uiiT 

 calories. As explained on page 258, small quantities of organic matter in the ventilating air cur- 

 rent were reckoned as alcohol, hence the figures in column d somewhat overstate the heat of 

 combustion of the alcohol given off unoxidized. The values in column e are obtained by multi- 

 plying the number of grams of protein gained or lost by the heat of combustion of one gram of 

 protein, which is taken as 5.65 calories. The estimated heat of combustion of fat gained or lost, 

 as shown in column/', is computed for the different days from the corresponding values in Table 

 XVII upon the supposition that each gram of fat has a heat of combustion of 9.5 calories, 1 which 

 has been found to be not far from the average for one gram of various animal fats. The esti- 

 mates of column ;/ are the heats of combustion of the. food eaten less the algebraic sum of the 

 heats of combustion of food, feces, and body material gained or lost. To put it in another way, 

 they are tlie heats of combustion of the food eaten and of body material lost less the heats of 

 combustion of feces, urine, and body material stored. They may be said to represent the net 

 income of energy to the body. The net outgo is measured directly by the apparatus, and is 

 show n in column It of Table XVIII. The net income averages in this experiment 5 calories per 

 day less than the net outgo. On different days of the experiment the net outgo varied from 25 

 calorie- below to .'i.'i calories above the net income. 



I 'eterminations of tin- heat of combustion of human body, fat made in this laboratory by F. <.. Benedict ami 

 E. Osterberg in 1900, and published in volume 4 of the American Journal of Physiology, page 76, indicate that the 

 heat nf combustion of body fat is nearly 9.54 calories per gram. This value was used in the computations of later 

 experiments, beginning with No. 26. See discussion of this subject by At water ami Bryant in Report of tin- Storrs 

 (Conn.) Experiment Station for 1899, p. 93.) 



