Laws of Molecular Force. 281 



contributed by each constituent of the molecule. Thus we 

 have characteristic of inorganic bodies in solution another of 

 those properties called by Valson modular, who discovered 

 that the density, capillary elevation, and refraction of normal 

 solutions (gramme-equivalent dissolved in a litre of water) 

 could all be obtained from the values for a standard solution 

 such as that of Li CI by the addition of certain numbers or 

 moduluses representing invariable differences for the metals 

 and Li and for the negative radicals and CI. Other properties 

 of solutions have since been proved to be modular, as for 

 instance their heats of formation from their elements and 

 their electric conductivities. I think the modular nature of 

 some of these properties of solutions is the outcome of this 

 modular property in the parameter reciprocal of molecular 

 force along with the additive property in mass. To prove 

 this in the case of density would require a special investiga- 

 tion, but if we assume the property tor density we can easily 

 deduce Valson's result that the property applies to capillary 

 elevation. Let h be the height to which a normal solution of 

 any salt RQ rises in a tube of radius 1 millim., then 



A= 2a / P =2X p t(^)*/, 



Let r and q be the density moduluses of the radicals R and 

 Q, being small fractions, then p—d+r+q where d is a con- 

 stant nearly 1 ; also 



X- 1 = ( W" 1 + nA~ 1 )/(l + n) , 

 so that 



Remembering that in the case of a normal solution n is small, 

 being 18/1000, we can develop the last expression in powers 

 of n as far as the first ; and it is evident that as p the mole- 

 cular mass possesses the additive property and A -1 possesses 

 the modular property, then h must also possess the modular 

 property, which is Valson's result. 



16. Second method of finding the virial constant for inorganic 

 bodies or solid bodies in general from the properties of their 

 solutions. — In this method the compressibility of solutions is 

 used. If a solution could be treated as an ordinary liquid we 

 might attempt to apply the equation of our second method for 

 liquids, namely, 



, 4/ a , 25 R T 



but as the solutions to be dealt with are all aqueous, and as a 

 Phil. Mag. & 5. Vol. 35. No. 214. March 1893. U 





