JOURNAL 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. V MAY 19, 1915 No. 10 



PHYSICS. — An aneroid calorimeter.'^ H. C. Dickinson and N. 

 S. Osborne, Bureau of Standards. 



The term "aneroid calorimeter" is applied to a type of calo- 

 rimeter in which equalization of temperature is secured by means 

 of the thermal conductivity of copper instead of by the con- 

 vection of a stirred liquid. The calorimeter consists of a thick 

 walled cylindrical vessel of copper, in the walls of which is 

 embedded a coil of resistance wire to supply heat electrically, 

 and of a platinum resistance coil for use as a thermometer; it 

 has been found useful over a wide range of temperatures and is 

 applicable to a variety of problems. 



For use at low temperatures the calorimeter is mounted in a 

 jacket surrounded by a bath of gasoline the temperature of 

 which can be controlled thermostatically to within a few thou- 

 sandths of a- degree at any temperature between —55° and 

 +40°C., or it can be changed rapidly in order to keep it the 

 same as that of the calorimeter when heat is being supplied 

 to the latter. Differences in temperature between the surface 

 of the calorimeter and that of the jacket are measured by means 

 of multiple thermocouples which have ten junctions distributed 

 over the surface of each, thus making it possible to apply accu- 

 rate corrections for thermal leakage between calorimeter and 

 jacket even when the temperatures of both* are changing rapidly. 



1 To appear in the Bulletin of the Bureau of Standards. 



337 



