Manchester Mevwirs, Vol. xlvii. [igo-i^), No. 11. 19 



the elements must be recognised, and one set of relations 

 will connect them all. In the arrangement proposed by 

 Reynolds the inert gases, the elements of zero valency, 

 appear at the nodes of a vibrating curve, a circumstance 

 which gives this method of presentation a peculiar force. 

 But for the consideration of physical properties the 

 curves drawn by Lothar Meyer seem likely to be the 

 most useful. In one respect, however, the periodic system 

 is still defective ; it fails to take adequately into account 

 the numerical relations between the atomic weights, a 

 phase of the problem which should not be ignored. Such 

 relations exist ; some of them have been indicated by your 

 distinguished fellow-member, Dr. Wilde ; and, elusive as 

 they may seem to be, they are surely not meaningless. 

 The final law must cover the entire ground, and then 

 atomic weights, ]Dhysical properties and valency will be 

 completely correlated. Prout's hypothesis is discredited, 

 and yet it may prove to be a crude first approximation to 

 some deeper truth, as the probability calculations of 

 Mallet* and of Struttf would seem to indicate. The 

 approaches of the atomic weights to whole numbers 

 are too close and too frequent to be regarded as purely 

 accidental. But this is aside from our main question. 

 The real point to note is, that the physical properties of 

 the elements are all interdependent, and that the funda- 

 mental constants are the atomic masses. 



Do I seem to exaggerate ? Then look for a moment 

 at the present condition of physical chemistry, and see 

 how moderate my statements really are. We have not 

 only the laws already mentioned, of Avogadro, of Dulong 

 and Petit, of F"araday and of Mendeleeflf, but also a multi- 

 tude of relations connecting the physical constants of 

 bodies with their chemical character. Even the wave- 



* PkiL Trans., vol. 171, 1881, p. 1003. f Phil. Mag., (6) i, p. 311. 



