20 Mr. W. Sutherland on Weak Electrolytes and 



latter is even CH 3 C(OH) 3 . Long ago Graham found that 

 the mixture of acetic acid and water having the composition 

 CH3COOH + H2O is the solution of maximum viscosity as 

 well as of maximum density. Moreover, C 2 H 5 OH-f 3H 2 

 has been isolated in the solid state like crystals with water of 

 crystallization. But here again I shall try to show that 

 there is excessive chemical simplification in the hypothesis 

 that these hydrates exist as definite molecular structures in 

 the solutions, and that a broader dynamical interpretation 

 is to be given to the facts. The scheme of the following- 

 work is this : — 



I. Formulation of the kinetic principle by which the 

 properties of mixtures ought to be investigated. 2. Detailed 

 examples of its application to the densities of solutions of 

 ethyl alcohol and acetic acid in water and the contraction 

 which occurs in their formation. 3. Similar results for all 

 the other chief physical properties of mixtures of water with 

 ethyl alcohol and with the first four of the series of fatty 

 acids, namely molecular refraction and dielectric capacity, 

 viscosity, specific heat and heat evolved on mixing, surface 

 energy. 4. Conclusions to be drawn from these results. 



5. Electric conductivity of solutions of the fatty acids. 



6. Summary and general conclusions. 



1. Formulation of the Kinetic Principle by which the 

 Properties of Mixtures one/Jit to be investigated. 



For the particular case of potential energy this principle 

 has been already stated in " Molecular and Electronic Poten- 

 tial Energy" (Phil. Mag. [6] xx. p. 249, 1910), and now it 

 will be made generally applicable to all the properties of 

 mixtures. The principle is fundamentally necessary in the 

 theory of molecular potential energy advanced in many of my 

 papers. Each molecule is simplified to an electrized sphere, 

 similar to the Earth as a magnetized sphere, having a certain 

 electric moment. The axes of electrization of contiguous 

 molecules tend to adjust themselves in such a way that a 

 molecule has its axis similarly directed to those of its two 

 next axial neighbours, and oppositely directed to those of its 

 four next lateral neighbours. In other words, the lines of 

 electric force pass from an electrized molecule partly in 

 almost straight lines to its two axial neighbours, and partlv 

 in closed curves through its four lateral neighbours, few 

 lines wandering to any molecules beyond the six immediate 



