346 
Journal of Agricultural Research 
Vol. V, No. 8 
of the coil, and the amperage of the current is measured by a milliam- 
meter in series with it, the readings of both meters being recorded every 
minute, or oftener. 
In a 2-hour test in January, 1915, the total heat production was 139.00 
Calories, while the quantity measured with the calorimeter was 139.04 
Calories. Such absolute agreement is not to be expected invariably, 
though with the conditions ordinarily prevailing in an electric check the 
two values should not differ by as much as 1 per cent. A discrepancy 
of that size would indicate need of attention to some part of the apparatus, 
or lack of attention to some details of operation. For example, in a 
3-hour test in February, 1915, the total quantity of heat generated in 
the chamber was 370.19 Calories and that measured by the calorimeter 
was 377.39 Calories. The discrepancy between the tw’o values was due 
to a considerable decrease in the temperature of the walls of the chamber 
during the last half of the first hour, resulting from a lowering of the 
temperature of the water entering the heat absorber. In the two hours 
following that the heat production was 245.87 Calories, as computed, and 
246.75 Calories, as measured, a discrepancy of less than 0.4 per cent. 
The results in the first hour illustrate the statement "made on page 340 
regarding error in heat measurement when the temperature of the copper 
wall changes so quickly that its thermal conditions differ from those of 
the iron structure to which the wall is attached. 
LITERATURE CITED 
(1) Atwater, W. O., Benedict, F. G., et al. 
1899. Experiments on tlie metabolism of matter and energy in the human body. 
U. S. Dept. Agr. Office Exp. Sta. Bui. 69 (rev. ed.), 112 p., 87 tab. 
(2) - - - 
1902. Experiments on the metabolism of matter and energy in the human body, 
1898-1900. U. S. Dept. Agr. Office Exp. Sta. Bui. 109,147 p., 151 tab. 
( 3 ) - 
1903. Experiments on the metabolism of matter and energy in the human body, 
1900-1902. U. S. Dept. Agr. Office Exp. Sta. Bui. 136,357 p., 14%., 
127 tab. 
(4) Atwater, W. O., and Rosa, E. B. 
1899. Description of a new respiration calorimeter and experiments on the con¬ 
servation of energy in the human body. U. S. Dept. Agr. Office Exp. 
Sta. Bui. 63, 94 p., 12 fig., 8 pi. 
(5) - 
1899. A new respiration calorimeter and experiments on the conservation of 
energy in the human body. I. In Phys. Rev., v. 9, no. 3, p. 129-163, 
12 fig. 
(6) -, Woods, C. D., and Benedict, F. G. 
1897. Report of preliminary investigations on the metabolism of nitrogen and 
carbon in the human organism, with a respiration calorimeter of 
special construction. U. S. Dept. Agr. Office Exp. Sta. Bui. 44,64 p. 
4 fig. 
