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BIOLOGICAL CHEMISTRY 



TABL 



To show the construction of a balanc 

 From W. O. Atwater, Ergebnisse der Physiologie, 



INCOME. 



any loss of heat by radiation, convection or conduction. The 

 inner chamber is made of copper and the outer of zinc. 

 Stretching between the two are a series of thermocouples 

 (E), so that if one casing is at a different temperature from the 

 other an electrical current is produced and this current is 

 shown by a galvanometer. If the outer casing is cooler than 

 the inner it can be warmed by an electrical current passing 

 through wires wound round it, and if it is warmer than the 

 inner casing it can be cooled by passing water through lead 

 tubes wound round it. The outer casing is surrounded by 

 wood, air and packing in several layers so as to prevent 

 fluctuations due to changes in external temperature.* 



* W. O. Atwater, Ergebnisse der Physiol., 1904, vol. 3, part I, p. 

 497- 



