308 SECTIONAL TRANSACTIONS.—B. 
with the precession and rotation of orbits, &c., &c. Chemically, of the various forms 
in which the polarity theory has been published, those which are unequivocal are 
contrary to experimental evidence ; the remainder consist of arbitrary alternatives 
which, in so far as they can be tested at all, are similarly refuted. 
The affinity theory, accepting the attractive force between non-ionised atoms—like 
gravitational and magnetic forces—as some given function of the atom, deduces for 
this force one single mechanism of transmission, in any chain. Its interpretation of 
chemical reactions is unequivocal, and is found to be in agreement with all well- 
authenticated observations. 
Prof. A. Lapwortn, F.R.S. 
The theory of reaction through activated polar forms is at present being developed 
by constant comparison with the requirements of modern physical chemistry. It 
is already of considerable service in grouping together phenomena of the most diverse 
character and thus helping us to foresee the probable results of new combinations of 
circumstances. In this respect it is at least on an equality with other recipes with 
which it has been unfavourably compared; in other respects it is immeasurably 
superior, especially in its close parallelism with the requirements of the ionic dissocia- 
tion hypothesis and with those features of the electronic theory of valency on which 
general agreement has been reached. 
The ‘ electro-affinity ’ principle of Abegg and Bodliinder—on which principle the 
author’s system was originally based—is but a special case of the entropy principle. 
Used mnemonically it is often helpful as a short theoretical cut, but often tends to 
obscure the real issues. For example, it takes no cognisance of cases where ions are 
not capable of forming bonds, or (in terms of a familiar theory) are ‘ co-valently ’ 
saturated. 
The terms ‘ diffuse’ and ‘ intense,’ as applied to free polar affinities, may be con- 
sidered from the entropy standpoint. A charged atom, X, in a polarised complex 
no doubt exerts at certain distances an electrostatic attraction on another oppositely 
charged atom Y, but may not be able to form a chemical bond with it, for one or more 
of several reasons ; for example, X may already be bond-saturated, as in ‘ ammonium- 
nitrogen.’ Putting it quite generally, the union may never be consummated by the 
formation of a bond if the product of this change would be one with very low entropy. 
In such cases, approximation between the two atoms would at first lead to a rise in 
the entropy of the joint system, but within some intermediate position to a fall; in 
other words, an attractive force must at some point vanish and be replaced by a 
repulsive force. The term ‘ diffuse’ has hitherto been used to express this property 
of certain polar free affinities or electrovalencies, and the term ‘ buffered’ is now 
suggested as a more satisfactory one. 
Prof. R. Roxtnson, F.B.S. 
The following points will be considered :— 
1. Polarity and reaction mechanism—fundamental principles. 
2. The meaning of the phase ‘ polar alternation ’ and of symbols such as A B C D 
EF, 
Stability of electronic configurations. 
fs 
3. The electronic theory of activation by polarisation of conjugated complexes 
and the mechanism of reaction of the polarised phases. 
4, The general polar effect—continuous electron displacement. 
5. Some prevalent fallacies respecting the polarity theory as illustrated by certain 
recent publications. 
6. Defects of the theory of non-polar alternation and corresponding advantages of 
the polarity theory. 
Prof. T. M. Lowry, F.R.S., Prof. C. K. Incoup, F.R.S. 
