34 



The heat of compression of a fluid 



dQ 

 dP ^ 



(12) 



is usually positive; thus, heat is released when a fluid is compressed and ab- 

 sorbed when the fluid is allowed to expand. If compression or expansion is 

 rapid, and heat conduction into the surroundings is slow, then the process will 

 be an adiabatic one, and the temperature will increase or decrease, respec- 

 tively o-^ In the present experiments, rapid compression will result in a 

 momentary increase of temperature and a corresponding transient decrease of 

 measured electrical resistance (see Figure 18); rapid decompression will give 

 rise to a transient increase of resistance (see Fi^re 19). These experiments 

 indicated that re -establishment of thermal equilibrium requires about 20 min- 

 utes . In all subsequent experiments, resistance readings were made following 

 each pressure change until a constant was obtained. 



S- 700 1-0307 



