
EXPERIMENTS ON DIGESTION OF FOOD BY MAN. Toy 
The figures for ‘‘ estimated heat of combustion’’ of urine in 
the above tables demand a word of explanation. In experi- 
ments 38, 40, 42, and 44 they are based upon direct deter- 
mination of the nitrogen and the heat of combustion of the 
water-free substance of the urine. In the others, 37, 39, 41, 
and 43, they are computed by assuming that the heat of com- 
bustion of the water-free substance of the urine will be 1.25 
calories for each gram of digested (available) protein. This 
factor is the average found in a number of experiments in this 
laboratory, in which the heat of combustion of the water-free 
substance of the urine was determined.. 
In the following table the results of the above experiments, 
Nos. 37-44, together with eight others, Nos. 45-52, are sum- 
marized. 
TABLE 42. 
Total amounts of nutrients and energy in the food consumed per 
day in the above experiments, and the proportion 
digested (available ). 

















B is 
. Be DESCRIPTION. Protein. Fat. aires Energy. 
First or Preliminary Period of by | 4-\G | Loa 4.\cal.| ¢% 
Metabolism Experiments. ey 4 eT sae neha Sa E 
37| 5 | Mixed diet, ordinary work, - |121192.7) 96.94.01275|98.0/2675|89.9 
39| 6 | Mixed diet, hard work, - - [119 90.1|154,95.3 378|97.6/3685/91.2 
41; 7 | Mixed diet, with alcohol, rest, - |105 90.9) 69 93.6/309 98 .3/2405/89.8 
43| 8 | Mixed diet, light work, - - |128 91. 4|/104/94.5|308/97.4|2y60/89.7 
45| 9 | Mixed diet, light work, - - |118 90.9} 69 92.1/340/95 .8|2705/88.4 
47| 10 | Mixed diet, with alcohol, rest, - |122/94.9| 31,92.1/419|98. 6|/2690'91 .3 
Ag| 11 | Mixed diet, hard work, - - |125/90. 6/129'93.2/484/97. joan ch 
51| 12 | Mixed diet, with alcohol, hard work| 123 95. 3/163 94.3 422/96. 4/3930 91.2 
Average eight periods, - 120 92.1102 93.6367 97.5.3115 90,3 
Second Period of Metabolism Ex- 
periments. Subject in Respir- 
ation Calorimeter. 
38, 5 | Mixeddiet, rest, - - - |1I1Q9f.4) 95.93.9/276/97.6/2655 90.0 
40| -6 | Mixed diet, hard work, - - |I19|92.2/153|96.9)378|98 . 3/3675|92.6 
42| 7 | Mixed diet, with alcohol, rest, - |104/94.7| 68 96.3 309/98.8/2395|91.8 
44| 8 | Mixed diet, rest, - - - |129/94.0) 96.95.6/308|98. 2/2895 90.7 
46} 9 | Mixed diet, rest, - : - |118|93.4| 69,93.9/340) g6.5|2705|89.5 
48| 10 | Mixed diet, with alcohol, rest, - 124/92.9) 31 88 .1/418197.8|2700|g0. 2 
50; 11 | Mixed diet, hard work, - - |125/88.8|129/93.0/485|97.5|3860|90.9 
52| 12 |\Mixed diet, ‘with alcohol, hard w tf 121/93.6/159/95.9/414/98. 7|3870|93.1 
ok: Average eight periods, - - |12092.6100 94.2 366 97. 9/3095 91.1 
