B.—CHEMISTRY. 81 
cent. of the crystalline silica has been converted by grinding into 
‘amorphous’ silica. The densities of silica glass and silver sand were 
found to be 2.208 and 2.638 respectively. After fifteen hours’ grinding 
the density of the latter was lowered to 2528. On the same assump- 
tion as before, it follows that about 26 per cent. of the quartz has been 
converted into the vitreous condition. The difference between the 
figures 31 and 26 is doubtless due to the approximate character of the 
assumption underlying the calculations and to experimental errors. 
There seems little doubt, however, about the soundness of the main 
conclusion—namely, that the mechanical action of shearing stress on 
erystalline matter is to produce a random molecular or atomic 
distribution in the surface layers. 
This discussion, necessarily brief and limited, of certain aspects of 
the properties of surfaces—molecular orientation, surface concentra- 
tion or adsorption, electrical or ionic polarisation—has dealt very largely 
with states of thermodynamic equilibrium. The chief interest of such 
studies has always appeared to me to lie in their possible ultimate 
bearing on the phenomena of life. We must remember, however, that 
the activities, and indeed the very existence, of a living organism depend 
on its continuous utilisation of an environment that is not in thermo- 
dynamic equilibrium. A living organism is a consumer and trans- 
former of external free energy, and environmental equilibrium means 
non-activity, and eventual death. 
It is probable, therefore, that along and across ‘ living surfaces’ 
there is a continual flux of activity. Does the very existence of these 
surfaces depend on some special sort of activity? Questions such as 
these must make us cautious as regards any premature generalisation 
from simple physico-chemical results. But there is encouragement if 
we may assume that the physico-chemical manifestations of life are 
functions of the same powers and potentialities of electrons, atoms, 
ions, and molecules that we find in what we call inanimate environ- 
ments. Life would then be simply a new functional relationship of 
very old parameters, at all events in so far as its various physico- 
chemical ‘mechanisms’ are concerned. 
In the totality of its activities and relationships, however, a living 
organism is an individual, and to arrive gradually at an understanding 
of this ‘ individualisation ’ it will be necessary to study very carefully 
the laws pertaining to the intimate and particlar modes of action of 
_ simpler individuals. The actions of an individual are conceived by 
science as determined by its internal state and by its relation to its 
environment. As we pass from certain peculiar atomic states, where 
the actions appear to have no relation to environment, to molecules, 
colloidal micelles, and living cells, the effects of the environment in 
determining activity seem to become more and more pronounced. 
The internal state of a living cell or organism may arrive from time 
_ to time at ‘critical’ points and ‘ critical’ transformations.. Whatever 
may be the relation of such possible critical states to the previous cell- 
environment reactions, the resulting events will be immediately deter- 
mined by the special internal nature and sctivity of the cell itself. Is 
_ this ‘ special internal nature and actiyity ’ simply a special type of 
H 3 
