870 SECTIONAL TRANSACTIONS.—A, 
3. The transition from the liquid to the amorphous or glassy condition at 
low temperatures may be investigated by the method of light-scattering. The 
bearing of the results on the nature of the amorphous state is discussed. 
4. Observations have also been made on the scattering of light in transparent 
crystals. 
*S. The relation of molecular anisotropy to natural and artificial double re- 
fraction, and to chemical constitution, is discussed. 
(b) Prof. F. B. Kenricx.—Light-Scattering of Aqueous Salt 
Solutions. 
The light-scattering and depolarisation factors have been measured for 
aqueous salt solutions prepared dust-free by the method of envelopment. The 
intensities of scattering are compared with the calculated values. 
(c) Prof. W. H. Marrin.—The Relation between the Depolarisa- 
tion Factor of the Scattered Light and the Electrical Double- 
Refraction in Liquids. 
Richard Gans’ theory of the relation between the depolarisation factor of 
the scattered light and the Kerr constant of electrical double-refraction in 
liquids is submitted to experimental test for some fifteen liquids. Measure- 
ments of the depolarisation factor for nitrobenzene made in a magnetic field 
of 5,000 gauss failed to show any change in the polarisation of the scattered 
light. 
35. Prof. L. B. Lozs.—Gas Ion Mobilities and their Independence 
of the Nature of the Ion. 
If an expression deduced by J. J. Thomson (Phil. Mag., 47, p. 345) for the 
shortening of the free path of a gas ion acting on neutral molecules according 
to an inverse fifth power law of force be introduced into the Langevin equation 
for the mobility of a gas ion, it can be shown that K, the mobility of the 
ion, is given by 
“815 ae 
R= PeaNyul 
Pp eee tr BS 
760 V (D—1)M, 
Here N, is the number of molecules per c.c., » is the mass of an H atom, p is 
the pressure of the gas in which the ion moves in mm., D the dielectric constant 
of the gas, M, its molecular weight, and 6 is the number of gas molecules 
in the ion. 
It is seen that except for the factor — (which varies from 1.4 to 1.0), 
K is independent of the nature of the ion. K is a function of p, M,, and D, 
but does not depend on the velocity of thermal agitation of the ion nor its free 
path. This is all in accord with experiment. The absolute values of the 
mobilities computed from the equation are in better agreement with observed 
values than those of any existing theory. 
36. Prof. Sir Ernest Ruruerrorp, F.R.S.—Lecture on Atomic 
Disintegration. 
Cosmicat Puysics SuB-sEcTION. 
37. Rev. A. L. Cortre.—The Relation between Solar Activity and 
Terrestrial Magnetic Disturbance. 
_ 1. A sun-spot of very great area is always accompanied, at some stage of 
its life history, by a magnetic disturbance. For instance, in the solar cycle 
