METHODS OF INVESTIGATION. 61 
group, and the determination of the gain or loss of each ingredient 
from a comparison of income and outgo is in principle a relatively 
simple matter and calls for no special consideration here. 
Fat.—The elementary composition of the fat of the body has 
been shown to be remarkably similar not only in different animals 
of the same species, but likewise in different species. The classic 
investigations of Schulze & Reinecke * upon the composition of 
animal fat gave the following results: 
Carbon. Hydrogen. Oxygen. 
No. of 
Sam- | Aver- | Maxi-| Mini- | Aver- | Maxi-| Mini- | Aver-| Maxi-| Mini- 
ples.| age |mum|mum| age |mum|mum|/ age | mum| mum 
Per | Per | Per | Per | Per | Per | Per | Per Per 
Cent, | Cent. | Cent. | Cent. | Cent. | Cent. | Cent.| Cent. | Cent. 
Beef fat......... 10 |'76.50/76.74)76. 27/11 .91112.11)11.'76)11 .59)11.86,11.15 
Pork fat........ 6 |76.54/76.78)'76.29/11.94/12.07/11 86/11 .52/11.83)11.15 
Mutton fat...... . 12 |76. 61/76. 85/76. 27/12 .03}12.16)11.87/11.36/11. 56) 11.00 
Average...... 28 |76.50 12.00 11.50 
Dog.....-seeeee 76.63 12.05 11.32 
Cat... .ccecsccces 76.56 11.90 11.44 
Horse.....+++-- 77.07 11.69 11.24 
Ma Nip:e-cresiearercievars 76.62 11.94 11.44 
Benedict and Osterberg ¢ obtained the following results for the 
composition of human fat: 
Carbon, Hydrogen, 
Per Cent. Per Cent. 
Sample No. 1........ 76.29 11.80 
a OO ID erode tienes 76.36 11.72 
“e  Bxwasmaes 75.85 11.87 
fe OC Aiea noste aia 75.95 11.85 
ee te coavardasarece 75.94 11.74 
ee BE [Grouaiaisdshcateva 16.07 11.69 
fe CUE a wiguaia dates 76.13 11.84 
ef © Saace<ee _ 16.05 11.81 
Average 76.08 11.78 
The fat of the body has been commonly regarded as containing 
76.5 per cent. of carbon. A gain of 100 parts of fat by the body 
*Landw. Vers. Stat., 9, 97. + Amer. Jour. Physiol., 4, 69. 
