CALORIMETERS. 
845 
the most exact of the modern methods are modifications of this. 1 D'Arsonval, 2 
in 1886, introduced the differential air calorimeter, which has this great advan- 
tage, that the loss of 
heat by conduction 
and radiation from 
the calorimeter coif 
taining the animal is 
compensated by a 
similar loss from a 
dummy calorimeter of 
similar size and con- 
struction. This 
method has been em- 
ployed, and still fur- 
ther modified, by 
Rosenthal 3 and 
Rubner, 4 but it will 
suffice here to describe 
only the latest form, 
that introduced by 
Haldane, Hale "White, 
and Washbourn. 5 In 
this calorimeter (Fig. 
85) the heat produced 
by the animal in one 
chamber is balanced by 
the heat given off by a 
• ~~~~ : : ■ 
Hale 
Fig. 82. — Diagram of Dulong's water calorimeter. 
hydrogen flame burning in another similar chamber. The amount of hydrogen 
burnt is estimated, and, 
knowing the heat of 
combustion of hydro- 
gen, one can calculate 
the calories produced 
by the quantity of 
hydrogen used in the 
experiment ; this num- 
ber of calories is equal 
to those given off by 
the animal. The cal- 
orimeter is so arranged 
that at the same time 
it serves as a respira- 
tory apparatus, and the 
determination of 
the intake of oxygen 
and output of carbon dioxide checks the result of the calorimetric observa- 
tion. 
1 Rosenthal, Arch. f. Physiol., Leipzig, 1878, S. 349 ; Richet, Arch, de physiol. norm, 
et path., Paris, 1885, tome vi. p. 237 ; Mosso, Arch. f. exper. Path. a. Fharmalcol., Leipzig, 
1890, Bd. xxvi. S. 316. 
" Journ. de Vanat. et physiol. etc., Paris, 18S6, tome xxii. 
3 Arch./. Physiol., Leipzig, 1888, S. 1. 
4 " Calorimetrische Methodik," Marburg, 1891; Beitr. z. Physiol. Carl Ludwig 
z. s. 70 Geburtst., Leipzig, 1887 ; Ztschr. f. Biol., Munchen, ' 1893-94, Bd. xxx. 
S. 92. 
5 Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 123 ; Hale White, 
Croonian Lectures, Lancet, London, 1897, vol. ii. ; and Brit. Med. Journ., London, 1897, 
vol. ii. p. 11. 
Fig. 83.— Diagram of air calorimeter (Haldane, 
White, and Washbourn). 
F. Layer of felt. 
C. Cage. 
M. 
A. Tubes for ventilation. 
H. Hydrogen flame. 
Manometer. 
