Mar. 1,1925 
Calorimetric Investigations with Cattle 
405 
because no practicable methods of 
measuring or estimating corrections 
have been found. 
These errors depend on changes of 
body temperature of the animal dur¬ 
ing an experiment, and change in 
amount of moisture upon the walls 
of the chamber during an experiment. 
Assuming, under the conditions of 
the experiments, the possibility of a 
change of ±0.6° F. ( 8 , p. 24-26) 
(0.3° F. per day, in the same direc¬ 
tion during a two-day period), the 
possible error in the daily heat deter¬ 
mination, in the case of an animal 
weighing 400 kg., would be ±53 
Calories. 
As to the mosture factor, there is the 
possibility of a deposit of moisture on 
the walls of the chamber, or of an 
evaporation of moisture from the same, 
during the experiment, thus constitut¬ 
ing an error in the measurement of the 
latent heat of water vapor produced. 
Under ordinary conditions this error 
is probably not appreciable. Its mag¬ 
nitude and direction would depend on 
the initial humidity in the chamber, 
length of the preliminary period, rate 
of ventilation, and water vapor given 
off by the animal. It is apparent that 
this error would be greater in short- 
time experiments than in those of 
longer duration. 
As regards the ultimate accuracy of 
the direct method, from a considera¬ 
tion of the results of the 18 alcohol 
check tests reported from this insti¬ 
tute by Armsby and Fries ( 5 , p. 200- 
222) the authors came to the conclu¬ 
sion that the results of a single experi¬ 
ment with the respiration calorimeter 
may be regarded as accurate to within 
approximately the following percent¬ 
ages of the amounts determined: Heat, 
1 per cent; water, 6.0 per cent. 
The determination of the carbon 
dioxide production, which is used in 
the indirect method, is regarded as 
accurate to within approximately 0.5 
per cent of the amount determined. 
The results of 14 alcohol checks 
made subsequent to the above-men¬ 
tioned report, in practically the same 
manner as before, and using heat 
values for anhydrous alcohol ranging 
from 7.07537 to 7.13107 Calories per 
gram, show also a close agreement 
between the computed and the observed 
values, the average percentages re¬ 
covered being as follows: Heat 98.9 per 
cent; water, 108.0 per cent; carbon 
dioxide, 99.9 per cent. The results of 
these 14 individual tests are set forth 
in Table VIII. 
It will be noted that in all these 
tests the observed heat is less than 
the computed. This rather uniform 
difference may be due either to the 
assignment of too high a heat value 
to the alcohol, or to the heat meas¬ 
urement, or to both. The range of 
the differences, however, is narrow. 
Considering the results of all the alcohol 
checks, and the fact that the possibility 
of error in short-time experiments is 
greater than in experiments of longer 
duration, the conclusion stated above, 
with regard to the accuracy of the 
direct heat measurement as well as to 
the carbon dioxide determination, seems 
to be warranted. 
Table VIII .—Results of alcohol check tests 
1 
Heat 
Carbon dioxide 
Water 
Date 
Num-I 
ber ofj 
hours 
Ob¬ 
served 
Com¬ 
puted 
Ob¬ 
served 
com¬ 
puted 
Ob¬ 
served 
average 
of 
aspira¬ 
tor and 
meter 
Com¬ 
puted 
j 
Ob- ! 
served 
*** 1 
com¬ 
puted 
j 
Ob¬ 
served 
average 
of 
aspira¬ 
tor and 
meter 
Com¬ 
puted 
Ob¬ 
served 
com¬ 
puted 
Calories 
Calories 
Per cent 
Prams 
Grams 
Per cent 
Grams 
Grams 
Per cent 
Nov. 23, 1911,... 
8 
4,085.4 
4,144.7 
98.6 
1,097.0 
1,110.8 
1,152. 9 
98.8 
732.6 
739. 3 
99.0 
Dec. 31, 1912_ 
8 
4,252. 6 
4,302. 0 
98.9 
1,170.1 
101.4 
852.2 
770.0 
110.7 
Apr. 29, 1913.... 
: 7 
3, 778. 9 
3,817.2 
99.0 
1,022.4 
1,023.0 
99.9 
759.9 
683.2 
111.2 
Dec. 4, 1913. 
! 7 
3,426. 8 
3,491.4 
98.2 
928.8 
935.7 
99.3 
679.3 
631.9 
107.5 
Apr. 28, 1914_ 
7 
3,397. 9 
3,440. 9 
98.8 
921.1 
922.1 
99.9 
698.9 
622.8 
112.2 
Dec. 17, 1914_ 
! 7 
3,481. 5 
3,507. 7 
99.3 
939.5 
940.1 
99.9 
671.8 
634.9 
105.8 
June 23, 1915_ 
7 
3,462. 8 
3,478.3 
99.6 
931.1 
932.2 
99.9 ! 
689.4 
629.3 
109.6 
May 9, 1916_ 
7 
3,507. 9 
3, 584. 5 
97.9 
965.1 
960.6 
100.5 
673.0 
647.4 
104.0 
Dec. 14,1917_ 
7 
3,294.8 
3, 331. 0 
98.9 
897.2 
898.3 
99.9 
651.6 
606.4 
107.5 
Jan. 3, 1918_ 
7 
3,252.1 
3,310. 5 
98.2 
884.4 
893.5 
99.0 
637.1 
602.3 
105.8 
Apr. 20, 1920_ 
8 
3, 534.0 
3, 540.8 
99.8 
« 955.8 
956.4 
99.9 
« 744.9 
644.6 
115.6 
Apr. 21, 1921_ 
8 
3,383.4 
3,390. 7 
99.8 
« 908.4 
915.9 
99.2 
“ 672.1 
617.2 
108.9 
Apr. 20, 1922_ 
8 
3,429. 6 
3,461.1 
99.1 
945.0 
934.9 
101.1 
® 676.0 
630.1 
107.3 
Nov. 24, 1922.... 
8 
3,495.2 
3,542. 3 
98.7 
949.4 
949.6 
100.0 
685.7 
637.7 
107.5 
Total_ 
Average-.. 
. 
49,782.9 
3, 555.9 
50,343.1 
3,595. 9 
98.9 
13,515. 3 
965.4 
13,526. 0 
966.1 
""99.9" 
9,824. 5 
701.8 
9,097.1 
649.9 
108.6 
By aspirator only. 
