Theories Regarding the Viscosity of Pure Liquids

In connection with the researches into the structure of liquids mentioned above, a series of very interesting attempts has been made to investigate the internal friction of pure liquids from the standpoint of molecular theory. 

Van der Waals, Jr. derived an equation for the coefficient of viscosity based on the idea that internal friction arises as it does in a gas, where the momentum is transmitted from molecule to molecule by collisions. He obtains for 7 the expression 

6 = energy difference between the average energy of a molecule and the energy at 

Andrade has proceeded on entirely different principles to obtain the following expression for t  

See especially Second Report on Viscosity and Plasticityy Amsterdam-New York, 1938, p. 38 et seq. and J. D. van der Waals, Jr., Proc. Acad. Amsterdamy 21, 743 (1918). 

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