472 SECTIONAL COMMUNICATIONS. 
dimensions. This proves to be the case, the molecular diameters, as deduced 
from viscosity, being 3°10x 10% cm. and 3:13x10* cm. respectively. The small 
difference is well within the limits of experimental error. 
Dr. S. H. C. Brices referred to the importance of Dr. Langmuir’s theory 
of atomic structure for the inorganic chemist. As a result of the remarkable 
insight with which the theory has been developed much light has been thrown 
upon many obscure phenomena in inorganic chemistry, and the theory will 
probably exert a profound influence upon the valency problem. 
At present the valency theory is unsatisfactory. On the one hand we have 
the idea of valency with all its modifications, such as partial valency, residual 
valency, &c., and on the other hand we have Werner’s theory of co-ordination, 
which is an affinity theory rather than a theory of valency. Dr. Langmuir’s 
work appears to bring us very near to the point where it should be possible 
to combine these various conflicting ideas into some wider and more harmonious 
conception. Thus if we regard the elements as compounds of kernels and 
electrons (denoting the kernel by the symbol of the element with a small & 
above, and the electron by E), we may look upon the eight electrons in the 
neon atom NekE, as being co-ordinated to the kernel, just as the chlorine atoms 
are co-ordinated to the carbon atom in carbon tetrachloride according to 
Werner’s theory. Similarly, potassium K*E and chlorine ClkE, unite to give 
a co-ordination compound, potassium chloride K*[CI1KE,], exactly as potassium 
chloride KCl and auric chloride AuCl; combine to give a co-ordination compound 
potassium aurichloride K[AuCl,]. The detailed development of this point of 
view (Phil. Mag., 42 (1921), 448) leads to the conclusion that the co-ordination 
of electrons is involved in all valency phenomena. In other words, Dr. 
Langmuir has brought us into a region where the co-ordination theory and the 
older theory of valency converge and meet. 
Dr. E. K. Rrpgat.—Among the difficulties of the static atom from a chemical 
point of view are the structure of the nitrogen molecule, the formation of 
cis- and trans-compounds in the ethylenic series, and the apparent gradual 
transition from a polar or ionised to an unionised compound. These can he 
overcome by making simple assumptions which still await experimental 
verification. 
The phenomena of the photo-electric effect, the specific heat of the alkali 
metals, and the concept of the critical energy increment in chemical reactions all 
indicate that in an assemblage of apparently like molecules at any temperature 
above 0° K molecules differ from one another in reactivity. This difference may 
be attributed to an alteration in the position of one of the octet or valency 
electrons relatively to the nucleus. This should be accompanied by a change 
in size and possibly in specific heat. 
The energy of activation is absorbed kinetically and stored in quanta 
potentially. That the inverse square law is found to hold good even to sub- 
atomic distances may be explained on the assumption that the atoms are static 
except during actual absorption or emission of energy, and act as small dipoles 
or magnets which orientate themselves during the passage of a charged body, 
electron or alpha particle, through their midst. All collisions therefore occur 
between the charged body and identical portions of the atoms where the inverse 
square law holds. That the variable force suggested by Sir J. J. Thomson and 
G. N. Lewis is limited in direction to a tube from nucleus to electron, 7.c. a 
radial force, is further supported by the fact that in the absorption or emission 
of energy the electron must rotate or oscillate. ‘That it oscillates rather than 
rotates is indicated by the experiments of Rutherford, showing that the inverse 
square law holds over large regions of the atomic volume, and by the empirical — 
relationship of Haber between the natural infra-red and ultra-violet atomic 
frequencies My2=my,?, where M and m are the nuclear and electronic masses 
respectively, a relationship comparable with the assumption of a spring vibrating 
with loads of unequal mass at each end. 
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