142 Dr. G. Bakker on the 



For small curvatures we may put P=p N9 and (11) becomes: 



pi-p*= r » 



whereas (10) in this case changes into: 



Really we may put in the latter case R = R K , 



»-*- K K 



§ 3. Latent heat of vaporization and surface-tension. 



We conceive such a number of spherical capillary layers 

 of equal curvature that they form together a unit of mass. 

 We assume these capillary layers to be parts of spherical 

 capillary layers that limit little drops of liquid of equal E. 

 If the quantities which are considered refer to the homo- 

 geneous liquid phase, we denote them by the index 1, whereas 

 we take for the homogeneous vaporous phase the index 2. 

 If the thermodynamic potential is represented by //,, we 

 have as the condition for the equilibrium of the capillary 

 layer : 



/j, 1 =/jl. 2 or € l — T7] [ +i> 1 v l = e. 2 —T7j 2 'tp 2 r 2 . . (12) 



If r signifies the latent heat of vaporization, we have : 



r = T(r) 2 -7) Y )=e 2 -€ [ +p 2 v 2 —p l v ] . . . . (13) 



The matter of the equally curved capillary layers is deter- 

 mined by two parameters. For one of these parameters we 

 take the temperature, while we leave the second provisionally 

 undetermined. We differentiate while the second parameter 

 remains constant and get : 



dr de 2 de l dv 2 __ dv x dp* _ dp x ,. 

 rfT = M - dJ +I>2 dT Pl Jl +l ' 2 dT~~ Vl dT * ^ } 



If we denote the spec, heat at constant second parameter by 

 c, we have : 



de l di\ , de 2 dv 2 



consequently : 



j^-c 2 c. + v,^ i lcW . . . . (15) 



