336 F. B. CIUTHKIE. 



neon, argon, krypton, xenon). All the other non-metallic 

 elements, with the single exception of nitrogen, 1 form 

 allotropes. 



These facts tend to support the hypothesis here put for- 

 ward, since, in the case of monovalent elements, variation 

 in the direction of the discharged electron produces no 

 alteration in the structure of the resulting molecule. 



l- . ,, is identical with ~ ! 



r~K n n — — >H 



With monatomic molecules there can also be no change 

 of direction. In the case of the metals, allotropy, where 

 it exists, as in tin, is a function of the temperature. Deter- 

 mination of the vapour densities of cadmium, mercury and 

 zinc show that the molecules of these elements are mona- 

 tomic. Mensching and Meyer have shown that this is 

 also the case with bismuth. Tammann 3 has shown further 

 that at — 40° (using the method of depression of the 

 freezing point of mercury) nearly all the metals have 

 monatomic molecules. 



My thanks are due to Mr. G. H. Knibbs, c.m.g., Common- 

 wealth Statistician, for his kindness in verifying and 

 abstracting certain references which I was unable to refer 

 to locally. Also to Mr. L. Cohen of the Chemist's Branch 

 of the Department of Agriculture, for preparing the 

 diagrams which illustrated the reading of this paper. 



1 A chemically active modification of nitrogen has been described by 

 E. J, Strutt, (Bakerian Lecture, Proc. Roy. Soc, 1911, A. 85, 219). 



2 Berichte, 1889, 22, 726. 



3 Tammann, Zeit. Physik. Chemie, 1889, 3, 441. 



