790 Dr. R. D. Kleeman on the Nature of the 



be the sum of a number of independent constants each of 

 which refers to one of the atoms in a molecule. The com- 

 ponent of attraction parallel to x or x\ of the element of 

 volume dx, . dy, . dz^ in D on the volume dx .dy .dz in C 

 whose coordinates are (x, 0, 0) is 



W<f>(z)($c a y(^^ dx .dy.dz. dx, . dy, . dz,, 

 where 



*= v / {(*+*i) 1 +yi s +«i 2 K 



and N denotes the number of molecules per c.c. The attrac- 

 tion of the whole slab D on the element dx .dy.dz is 

 therefore 



+ 00 +00 +00 



W(tc a ) 2 [ f ( <j>{z) < ^^ ) dx.dy .dz.dx,.d yi .dz, = W{tc a )^ 







say. The work done in moving this element of volume to 

 infinity is 



j W(tc a f¥.dx. 



The work done in moving to infinity a cylinder of unit cross- 

 section and infinite length, standing with its base on the 

 plane AB is, therefore, 



+ 00 +00 +00 +00 +c 



• %) */ *y */ 

 x -co —oo 



and this is equal to 2\. If the density of the liquid is 



denoted by p and the molecular weight by m, N= — , 



and denoting twice the value of the above integral by k" 

 the result may be written 



which is a relation similar in form to that obtained 

 previously. 



We have seen that an application of this equation to the 

 facts showed that /c" is the same for all liquids at corre- 

 sponding states. It follows from this investigation that 

 the function <f>(z) must be of the form <j>(z, a, /3), where 

 p — otp c and T = /3T C , which will make k" assume the same 

 value for all liquids at corresponding states. 



