

A Calorimeter for the Human Body. 233 



was communicated to the middle chamber, and from the position of the 

 meniscus in the manometer, the initial temperature of the experiment 

 and the barometric pressure, the heat emitted in a given time was 

 indirectly calculated. 



Experiments were made on man with a modified form of this 

 instrument by enclosing an arm in one of the two inner chambers. 

 Hirn* investigated the heat emitted by man by making use of a 

 wooden chamber in which he had previously ascertained the rate of 

 loss of heat through its walls. This was done by burning a known 

 volume of hydrogen gas within the chamber until the temperature 

 became constant, and then determining the heat lost per unit of 

 time, from the known volume of gas burnt. This method at first 

 sight commended itself by its simplicity, but was open to two objec- 

 tions the first that it was an indirect method of inquiry, the second 

 that the person under experiment was unavoidably subjected to a 

 high temperature. 



In 1889 Bichetf published an elaborate investigation on animal 

 heat, in which he made use of a calorimeter constructed in such a 

 way that the heat emitted by an animal in a closed vessel displaced 

 by pressure a volume of water equal to the expansion of the air in 

 the calorimeter. 



An ingenious animal-calorimeter was constructed lately by Messrs. 

 J. S. Haldane, W. Hale White, and J. W. Washbourne.J These 

 gentlemen determined the heat given out from an animal, by com- 

 paring the pressure resulting from the expansion of the air in a 

 closed jacketed space surrounding the chamber containing the 

 liinal, with the corresponding expansion produced by the burning 

 )f a known volume of hydrogen gas in another similar vessel. The 

 amount of gas burnt is regulated with a stopcock, so that its heat 

 should correspond exactly with that produced in the other chamber 



indicated by a differential manometer. The heat emitted is equal 

 to that of the combustion of the gas burnt. 



Messrs. W. O. Atwater and E. B. Rosa, of Connecticut, U.S., 

 have quite recently measured the heat emitted from a person by 

 placing him in a large calorimeter, where he lived for periods of from 

 one to twelve days. The walls of the chamber were double, and 

 made of sheet copper and sheet zinc, while the heat generated was 



* " La Thermodynamique et 1'etude du travail chez les e'tres vivants," ' Revue 

 Scientifique,' 1897. ' Kecherches sur 1'lSquivalent mecanique de la Chaleur.' 

 Colmar, 1858, pp. 51, 95. ' Exposition analytique et experhnentale de la Theorie 

 mecanique de la Chaleur.' Paris, 1875, p. 35. 



t " La Chaleur animale," par Ch. Eichet, ' Bibl. Sc. Internat.,' 1889. 



J ' The Journal of Physiology,' 1894, p. 123. 



" An Apparatus for verifying the Law of Conservation of Energy in the 

 Human Body/' Brit. Assoc., 1897, Toronto, Trans, of Sec. A (General Physics). 



s 2 



