31 
Table 24. — Weight, composition, and heat of combustion of foods — Metabolism experiment 
No. 13. 
Lab- 
ora- 
torv 
No. 
Pood materials. 
Weight 
per day. 
Wat H Sn. Fat 
Carbo- 
hy- 
drates. 
Nitro- 
gen. 
Car- 
bon. 
Hydro- He at of 
' eombus- 
gen - tion. 
2962 
Beef 
Grams. 
235 
45 
750 
275 
50 
25 
40 
Grams. Grams. 
166. 1 59. 
4. 5 .5 
650. 3 27. 
102. 3 23. 6 
2.9 , 5.6 
1.3 1.4 
Grams. 
4.7 
38.3 
24.0 
14.0 
4.1 
2.7 
Grams. 
12. 8 
131.7 
36.5 
19 2 
Grams. 
9 40 
Grams. 
Grams. 
4.86 
4.54 
7. 80 
3.1.91 
3.21 
1.67 
2.59 
Calories. 
371 
351 
565 
816 
223 
112 
2956 
Butter 
.09 28.60 
4.35 51.98 
3.79 81.10 
22. 41 
•»> n ifi 
2959 
2963 
Milk (whole and 
skimmed) 
Bread 
2960 
Maize breakfast 
food 
2961 
Cookies 
Sugar 
40.0 l 16.84 
158 
Total 
1,420 
927.4 117.1 87.8 
270.2 18.74 245.84 : 36.58 
1 I 1 
2, 596 
Table 25, — Weight, composition, and heat of combustion of feces- 
No. 13. 
Meta bolisrn exper iment 
Lab- 
ora- 
tory 
No. 
Weight 
of feces. 
Water. 
P ™" Fat 
tern. rdU 
Carbo- 
hy- 
drates. 
Nitro- Car- 
gen, bon. 
Hydro- 
gen. 
Heat of 
combus- 
tion. 
2965 
Total, 4 days 
Average, 1 day . . . 
Grams. 
296 
74 
Grams. 
206.6 
51.7 
Grams. Grams. 
27. 5 24. 6 
6.9 6.2 
Grams. 
20.7 
5.2 
Grains. Grains. 
4. 41 44. 52 
1.10 11.13 
Grams. 
6.33 
1.58 
Calories. 
500 
125 
It has proved a difficult matter to preserve urine so that there shall 
be no decomposition of the urea into ammonium carbonate. About 2 
cubic centimeters of commercial formalin was added to the composite 
sample of the urine for each day as a preservative, but owing to una- 
voidable delays it was, in many instances, impossible to determine the 
heat of combustion of daily samples until some days after the experi- 
ment closed. In experiment No. 13 the heat of combustion of the com- 
posite sample for the four days was found to be 0.081 calorie per gram 
fresh urine, corresponding to 677 calories for the total urine for the 
period. Later determinations of the heat of combustion of the daily 
composites gave results showing that a decomposition of the urine had 
been going on. This decomposition was not shown by a loss of any 
appreciable amount of nitrogen, the decomposition products remaining 
largely in solution. The heat of combustion of the urine was, however, 
largely reduced. This is easily understood by comparing the heat of 
combustion of urea with that of ammonium carbonate, the former 
having a heat of combustion of 2.537 calories per gram as compared 
with 0.75 for the latter as actually determined in one sample of com- 
mercial ammonium carbonate. In this experiment, therefore, the 
heat of combustion of urine for each da}' is computed after the same 
