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.MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



The experimental data recorded in detail in the preceding tables can be summarized in 

 "derived " tables showing the balance of income and outgo of matter and. energy, the amounts of 

 materials excreted under different conditions and at different times of the day, and other points 

 of interest. 



Nitrogen and carbon balance. — The daily income and outgo of nitrogen and carbon in this 

 experiment are summarized in Table XV. The quantities of nitrogen and of carbon in the food, 

 feces, and urine are derived respectively from Tables VI-VIII, the quantity of carbon in the 

 respiratory products from Table XI, and the alcohol eliminated from Table XIV. 



Nitrogt nous matt rials and watt r ofpt rspiration collected in clothing. — It will be noticed that 

 the figures in column c of Table XV, nitrogen in urine, differ slightly from those given in Table 

 VIII. The subject changed his underclothing each night. The gain in weight of the underclothes 

 from the time they were sent into the chamber until they were sent out was taken as water 

 absorbed, and the amount thus removed is added to that in column e of Table XVI. "Water in 

 respiratory products." The underclothes taken out were extracted with distilled water, which 

 was afterwards evaporated nearly to dryness, the residue made up to a given volume, and the 

 nitrogen determined by the Kjeldahl method. The nitrogen thus given off amounted, in this 

 experiment, to 0.'.>6 gram for the 4 days. This amount has been divided equally between the 

 different days of the experiment and added to the amount of nitrogen in the urine. The sums are 

 given in column c of the following table: 



Table XV. — Tncomt and outgo of nitrogen and carbon — Metabolism experiment No. li. 



" Including nitrogen of perspiration. The nitrogen thus given off amounted to 0.96 gram for the four days, and 

 has been divided equally between the different days of the experiment and added to the amount of nitrogen in the 

 urine. 



Hydrogen balance. — The income and outgo of hydrogen and water upon the different days 

 of this experiment are shown in Table XVI. The figures are collated from the previous tables. 

 The values for water of respiration and perspiration have been increased by the amount absorbed 

 by the underclothing on each day, and therefore differ from the corresponding values as found 

 in the last column of Table XII. The water thus absorbed by the underclothing and removed 

 from the apparatus amounted to 63, 10, 12.3, and 7 grams, respectively, on the successive days of 

 the experiment. The apparent loss of water is shown in column f of the table. The quantities 

 in this column are always negative, since the water given off in the respiratory products is derived 

 not only from the water taken into the system with food and drink but also from the oxidation of 

 hydrogen and organic compounds. When, therefore, we consider the income and outgo of water, 

 the bod}' is apparently losing because of the oxidation of hydrogen within the body to form 

 water. The figures of column /', therefore, represent water apparently but not actually lost 

 from the body. The quantities in columns r/, //, and i of Table XVI represent the amounts of 

 hydrogen in organic combination in the food, feces, and urine, and the values in column I show 

 the apparent gains of hydrogen. The quantities in this column are always positive, owing to the 



