942 Dr. S. A. Shorter : Contribution to the 



approximately respectively the values 320, 640, 53, and 

 higher values. 



4. It may happen that for a certain pressure of the gas 

 and intensity of electric field the chance of a negative cluster 

 to get broken up in passing over a given distance is less than 

 the chance of a positive ion to produce a new ion by collision. 



5. The number of different clusters in a gas is to a certain 

 extent indicated by kinks on a curve. It appears that the 

 majority of negative clusters consist of one kind only. 



6. The kinks in the curve enable us to obtain the mean 

 free path of disintegration of a cluster under the conditions 

 of the experiment, that is, the distance a cluster has to run 

 under the electric field before getting disintegrated. Thus, 

 when the disintegration was due to the effect of the electric 

 field, the mean free path was '5 cm. in the gases C0 2 and H 2 , 

 corresponding to the pressures 4 and 15, in mm. of mercury, 

 and the fields 3720 and 960, in volts per cm. 



7. A theoretical formula for the mean free path of dis- 

 integration was deduced. 



In conclusion I wish to thank Sir J. J. Thomson for the 

 interest shown in this research, which was carried out at the 

 Cavendish Laboratory. It should also be mentioned that the 

 cost of the air-condenser, and the other part of the apparatus 

 (used previously), was covered by a research grant from the 

 Royal Society. 



Cambridge, 

 January 20, 1914. 



CII. Contribution to the Thermo dynamical Theory of Ter- 

 nary Mixtures. By S. A. Shorter, D.Sc, Assistant 

 Lecturer in Physics in the University of Leeds*. 



Contents. 



1. Introduction. 



2. General Theory of Chemical Potential in a Ternary 



Mixture. 



3. The Variation of the Chemical Potentials with the 



Composition of the Mixture. 



4. Equilibrium between Liquid and Vapour Phases. 



5. Solubility Influence. 



6. Osmotic Equilibrium. 



7. Partition Equilibrium. 



8. The Freezing of Ternary Mixtures. 



1. Lntroduction. 



THE present paper deals with th^ purely thermodynamical 

 theory of certain two-phase ternary systems, which 

 have hitherto been studied mainly from a physico-chemical 

 standpoint. * Communicated by the Author. 



