64: Speyers — Heat of a Change in Connection with 



It will be coijvenient to put v^ — V"^ in which case Q is the 

 heat of vaporization of 1"^^ of liquid. 



The data for carbon dioxide cannot be used without extreme 

 extrapolation. 



In the following table, t is the temperature of ya23orization, 

 p is the pressure in atmospheres, d^ is the weight in grams of 

 1"^^ of liquid at f and under jp pressure, d^ is the weight in 

 grams of l^'^ of saturated vapor at t\ v^ is the volume of satu- 

 rated vapor at t^ produced from 1^° of liquid at f , K2 is the 

 dielectric constant of the saturated vapor and K^ that of the 

 liquid, both at f and under j? pressure. 



^0 



p di 



cU 



^2 



K2 



K, 



Q 



AlO* 



so, 23° 



3-60' 1-37' 



0-0107' 



128 



1-031' 



14-8' 



114^ 



140 



NH3 18" 



7-89^ 0-612^ 



0-0055' 



111 



1-058* 



20" 



181' 



175 



H,0 140° 



3-57' 0-95' 



0-0020' 



475 



1-027' 



40 



48r 



154 



' Tabellen ; 



L. and B. 















' Tabellen ; by interpolation and computing for 1^^. 



' Linde ; Wied. Ann. Ivi, 563 (1895). 



" Badeker ; Zeitsch. phys. Chem. xxxvi, 305 (1901). By interpo- 

 lation and calculating to jt> by Boltzmann's rule. 



' Calculated by Boyle-Avogadro law. 



^ Franklin and Kraus ; Am. Chem. Journ. xxi, 14 (1899). 



' From Tabellen dp/dT between 135° to 145° = 77. 2^^ Hg. 

 Taking 0-95 as the density of liquid water at 140°, we have 

 v^ = 475 and 



^ 418(475-1)7.72 -13.6 ^ 

 ^ 42750 



Substituting these values in 5, we get for A the values given 

 in the last column. They were considered close enough to 

 warrant further research, particularly as the uncertainties in 

 the tabulated data are unknown and a slight change in K 

 makes a large difference in A. For instance, putting 1-030 

 instead of 1-027 for the dielectric constant of water vapor gives 

 0-0173 for A instead of 0-0154. 



In continuation of this line of w^ork, a simple investigation 

 seemed to be one into the heats of solution. Carbon com- 

 pounds in carbon solvents were chosen to avoid complications 

 which might arise from the presence of a metallic component 

 and because a considerable quantity of necessary data had 

 already been accumulated. 



The dielectric constants were measured by the method of 



Drude.^ It seemed advantageous to put a layer of sheet 



rubber on the secondary coil of the Tesla transformer and to 



wind the three turns of the primary on that instead of on a 



* Wied. Ann., Ixi, 466 (1897). Drude's Ann., viii, 336 (1902). 



