[SATTERLY] SURFACE TENSION, ETC. 87 



I have quoted from Waterston's paper in detail because, as 

 Lord Rayleigh remarked with reference to the famous paper by 

 Waterston on "The Physics of Media that are composed of free and 

 perfectly elastic molecules in a state of motion" which was refused 

 publication by the Royal Society in 1846 and only published by the 

 Society on Lord Rayleigh's advice in 1892. "Waterston's views 

 upon physics and upon chemistry also were much in advance of those 

 generally held at the time ..." 



In recent years the ideas of Waterston upon the connection 

 between latent heat and evaporation have been worked upon by 

 others without reference being made in any instances, as far as I 

 have noticed, to Waterston's prior calculations. Thus Hammick in 

 Phil. Mag 38, p. 240, August, 1919, following Matthews (Jour. 

 Phys. Chem., 1916, XX, 555) obtains 



QTV 



where T = surface tension (energy is stated but tension is taken) . 



</ = molecular diameter. 



F = volume of one gramme-molecule. 



Li = internal latent heat of vaporisation of the gramme mole- 

 cule. 



The ratio — is the same whatever quantity of liquid be taken. 



If, following Waterston, we make in the mass of a cubic inch we get 



Y ~T 



and since d = m, Hammick 's equation 



QTV 6T _ 

 — y~ = Li becomes Lip 



m 



er 6 



or m 



L,p QU 



which is Waterston's relation, with the exception that Waterston 

 does not discriminate between the internal and total latent heat. 

 Hammick gives a long table comprising 29 substances and says 



^u 1 ^' u- TV _L, 



tne reiationsnip — - — — ç^^s the facts remarkably well. He expresses 

 o D 



these qliantities in calories. Rudorf in Phil. Mag., Vol. 39, p. 238, 



points out that for argon which is quoted by Hammick the data 



TV _ Li 



employed were incorrect and instead of getting —r — ^^^ ^"^^ ~ = 214, 



