446 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



then increased to its original value and the change of volume noted. 

 These changes of volume were small and were measured with a cathe- 

 tometer. The observations were made rapidly, and the apparent 

 change of volume had, therefore, to be corrected for the error due to 

 the heat of compression. This correction was made in the same way 

 in which it was made in Part I of this paper. Here one has, however, 

 to assume that the specific heat of the liquid is about the same in the 

 superheated state as it is when the liquid is not superheated. As it 

 would require a change often per cent in the specific heat to prodace 



TABLE VIII. 



COMPEESSIBILITY OF EtHYL EtHER IN THE SdPERHEATED StATE. 



an error of about one per cent in the compressibility, this assumption 

 seems justified. 



In Tables VIII and IX are given the results for ethyl ether and for 

 ethyl alcohol. Each of the values tabulated in the fourth column of 

 these tables is the mean of twenty observations, ten made by decreas- 

 ing and ten by increasing the pressure. The mean values in the fifth 

 column have a probable error of about one per cent. In these tables 

 F is the vapor-pressure in centimeters of mercury at the corresponding 

 temperature t. In finding the values of k, pressures are reckoned in 

 atmospheres. 



