CH. XL.] 



CALORIMETERS. 



599 



It consists of two precisely similar chambers made of thin 

 sheet copper. Each chamber has two walls between which is an 

 air space ; and the outer is covered by a thick casing of felt (F) 

 to prevent fluctuations in the temperature of the surroundings 



Pig. 447. Dulong's calorimeter: C, calorimeter, consisting of a vessel of cold water in 

 which the chamber holding the animal is placed ; G', gasometer from which air is ex- 

 pelled by a stream of water. The air enters the respiratory chamber. G, gasometer 

 receiving the gases of expiration and the excess of air. t, t', thermometers ; a, a 

 wheel for agitating the water. Observe the delivery-tube on the left is much twisted 

 in the water-chamber, so as to give off its heat to the surrounding water. (From 

 McKendrick's " Physiology.") 



from affecting the air in the air-space. The chambers are 

 made perfectly air-tight, except for the ventilating tubes AA, A' A'. 

 By means of these, the chambers are filled with perfectly dry air 



Fig. 448. Air calorimeter of Halilnue. Hale White and Washbourn. C, ('-age for animal. 

 In onliT to make tin- cnnilitioiis in both rhaiiilwrs as much alike as possible, an emipu 

 cage should ! I'l.-iml in the other chamber. 



before the experiment is commenced. Leading from each air- 

 space is a tube ; the two tubes are connected to the two limbs of 

 a manometer (M) shaped as in the figure, and containing oil of 

 erigeron. 



The action of the calorimeter is as follows : In one chamber, 



