TRANSACTIONS OF SECTION B. 499 
he says: ‘If there was a simple law connecting the critical constants of mixtures 
with those of the constituents, we might calculate the constants for the second 
substance [those of the first being known]. But such is not the case. Pawlewski’s 
law that the critical temperature is proportional to the composition, expressed in 
weight units, is very inaccurate, the deviations being sometimes considerable in 
both directions.’ 
It would, I think, be of great interest if Professor Kuenen could find time to 
carry out further experiments with mixtures of ethane and butane in order to 
settle this point, or, perhaps, with n-hexane and n-octane, both of which can be 
more easily obtained in a pure state. 
From what has been said it may be concluded that, in order to ascertain the 
normal behaviour of pure substances under different conditions, or to find the 
simplest relations between the boiling-points, molecular volumes, or other physical 
constants of a series of substances, or, again, to ascertain the normal behaviour of 
substances when mixed together, and the properties of the mixtures as compared 
with those of the components, it is undoubtedly advisable—at first, at any rate— 
to confine our attention to substances of which the molecules show no signs of 
association in either the gaseous or liquid state. 
In the case of mixtures it is also best to begin with substances which are 
chemically closely related to each other. 
The following Papers and Report were read :— 
1. The Relation between the Crystalline and the Amorphous States as 
disclosed by the Surface Flow of Solids. By G. T. Brizpy, 
In former papers the phenomena observed in connection with the flow of solids 
have been fully described, and in the most recent of these the results of the 
observations have been applied to the study of the hard and soft states in metals. 
The purpose of the present paper is to direct attention to the very general 
character of the relations which have been found to exist between the amorphous 
and the crystalline states. 
Observations on flow in crystalline substances are described and illustrated by 
photo-micrographs. By the use of etching in stages the successive layers of a 
polished or disturbed surface are disclosed, from the smooth vitreous surface, 
through a granular layer, to the undisturbed crystalline body beneath. The 
demonstration that the polish of a lens of rock crystal has resulted from the 
formation of a flowed layer of amorphous phase on its surface suggests that no 
crystalline substance is too hard to yield to the mechanical flowing action. 
The passage of the amorphous back to the crystalline state by the agency of 
heat is discussed, and attention is directed to the important bearing of the fact 
that this transformation occurs at a definite temperature, on the behaviour of 
solids at ordinary atmospheric temperatures. It is suggested that as the stability 
point of ice is probably a long way below the freezing point, the amorphous phase 
can only have a transient existence at ordinary atmospheric temperatures; while 
at the lower range of winter temperatures within the Arctic Circle, the amorphous 
phase, once formed, may be stable and permanent. 
The grinding of crystalline substances to powder does not simply consist in 
their reduction to finer and finer crystalline fragments, but it involves the transfor- 
mation of at any rate a part of the substance into the amorphous condition. 
When crystalline powders are formed into cakes by pressure the cementing 
material is the amorphous phase which results from flow. 
In metals, and probably in most other solids, the physical and other properties 
of the two phases are so distinct that it is not difficult to determine the transition 
temperature or stability point in the transformation A > C. 
* _ From the existence of a definite stability point it is argued that not only must 
all crystalline substances be capable of existing in the amorphous as well as in the 
crystalline state, but that, by purely mechanical means, it is possible to transform 
them into this state. 
EK2 
