ie - 
_ May 19, 1923] © 
bility of coal dust. Stopes recognises four 
fairly distinct constituents with different physical 
and chemical characteristics in bituminous coal. 
The “ anthraxylon ”’ of Thiessen, regarded as being 
derived from wood rather than from general plant 
debris, seems to correspond on the whole to the 
‘clarain of Stopes, whose classification is based on 
_ present constitution rather than probable derivation. 
Physical Society, April 27—Dr. Alexander Russell 
in the chair—J. W. Ryde and R. Huddart (Research 
Staff of the General Electric Co.): The analysis of 
bubbles in glass. In order to distinguish bubbles 
generated is chemical action in glass from those 
introduced by mechanical processes, spectroscopic 
tests are made for the presence of nitrogen. To 
liberate the gas from the bubbles a specimen of the 
glass is placed in one limb of a quartz U-tube contain- 
ing mercury; the glass is heated and disintegrated 
by sudden cooling, the tube being plunged into cold 
water at the same time that the mercury is thrown 
on to the glass.—H. P. Waran: A simple regenerative 
vacuum device and some of its applications. Residual 
traces of air foul the vacuum above the mercury 
column in syphon gauges and other devices. A bent 
capillary tube ending in a bulb attached to the top 
of a siphon gauge will remedy this. It enables the 
air to pushed repeatedly into the vacuum of this 
bulb, the mercury at the bottom of the capillary 
preventing the subsequent return of the air. The 
device is regenerative in the sense that, irrespective 
of any progressive fouling of the vacuum, a fresh- 
air-free vacuum is automatically created by it every 
time it is brought into action.—-H. Shaw and E. 
_ Lancaster-Jones: Application of the E6tvés torsion 
balance to the investigation of local gravitational 
_ fields. In view of the sensitivity of the balance, 
which measures derivatives of gravity of the order 
of 10-* C.G.S. units, it was anticipated that a 
gravitational survey of the laboratory would disclose 
the varying effects of the neighbouring masses of the 
walls, pillars, etc. The consistency of the results 
_ obtained at each station and their general agreement 
with the calculated effects exceeded expectations, 
as the local gravitational field varied so rapidly that 
the theoretical assumption’ of a uniformly varying 
field in the neighbourhood of a station was obviously 
vitiated—L. F. Richardson: An _ electromagnetic 
inductor. Two bicycle wheels are mounted vertically 
and co-axially, and are driven in opposite directions 
by a 4-volt motor, the driving band being constituted 
by an endless wire. The electromotive forces 
generated by the revolution of the wheels in the 
_ earth’s field are thus added, the rims of the wheels 
being electrically connected through the driving wire. 
The speed of the wheels is found by counting the 
revolutions against a stop-watch, one of the spokes 
being marked for this purpose, and from this speed 
and the length of a spoke the E.M.F. can be found 
in terms of H.—F. Ll. Hopwood: Pulfrich’s experi- 
ment demonstrating time-lag in vision. The time-lag 
in visual perception is greater for dimly than for 
brightly illuminated objects. A pendulum carrying 
a glow lamp at its lower end swings over a second 
glow lamp fixed immediately below the mid position 
of the swinging lamp. Both are viewed with one 
eye, while in front of the other eye a metal disk 
perforated at its centre is placed. The pendulum 
then appears to be a conical instead of a plane 
pendulum, the ppearect direction of rotation chang- 
ing when the disk is transferred from one eye to the 
other, The image seen by the obstructed eye 
corresponds to an earlier position of the swinging 
lamp than does the image seen by the free eye, in 
consequence of the greater time-lag in the former case. 
NO. 2794, VOL. I11 | 


NATURE 
691 

Paris. 
Academy of Sciences, April 23.—M. Albin Haller 
in the chair.—Henri Lebesgue: The singularities of 
harmonic functions.—G. Bigourdan: The propaga- 
tion of Hertzian waves over great distances: the 
order of magnitude, in time, of the perturbations 
of the propagation. An analysis of the measure- 
ments obtained at five observatories of the time taken 
by the 300 rhythmic signals (about 4 m. 53 sec.) sent 
out by the military wireless station at Paris each day. 
The observed times are not affected by the atmo- 
spheric perturbations, nor by the receiving apparatus. 
—A.deGramont: The use of the oxyacetylene blow- 
pipe in spectrum analysis. Applications to miner- 
alogy. Compared with the oxyhydrogen or oxygen- 
coal gas flames, there are more lines in the spectra, 
and the time of exposure can be shortened. Repro- 
ductions of flame spectra obtained by this method 
from chromite, oligiste, and lepidolite mica are given. 
—C. Guichard: The triply indeterminate systems 
of © circles —L. Cuénot and L. Mercier: The flight 
muscles in the winged forms of Drosophila melano- 
gastey—N. Gunther: An auxiliary theorem.—Paul 
Lévy: The application of the derivative of non- 
integral order to the calculus of probabilities.— 
René Lagrange: Varieties without torsion.—Maurice 
Fréchet: The distance of two ensembles.—Alf. 
Guldberg : The problem of drawing from lottery urns. 
—Stanislas Millot: The probability of the existence 
of biological laws.—D. Riabouchinski: The paradox 
of d’Alembert.—M. Sudria: The determination of 
the position of flexure in a bent beam,—A. Leduc: 
A new equation of state for gases. The expression 
RT v ; a ye ] 
: P= M coer 3 165 +a 1) |; 
which is based on compressibility experiments 
between 1 and 2 atmospheres only, has been applied 
to the results of Amagat for carbon dioxide. Over 
a pressure range between 31 and 100 atmospheres 
and at temperatures from 0° C. to 100° C., the relative 
differences between the experimental result and that 
calculated from the above equation do not exceed 
+o-6 per cent.—Hector Pécheux: The magnetism 
of nickel. Magnetic measurements are given for 
three samples of nickel (the analyses of which are 
given) without heat treatment, after tempering and 
after annealing.—Nicolas Perrakis: Contribution to 
the cryoscopic study of binary organic mixtures. 
An account of a cryoscopic study of the systems 
phenol-ethyl alcohol, o-cresol-ethyl alcohol, phenyl 
ether-ethyl alcohol, benzene-methyl] alcohol, benzene- 
isopropyl! alcohol, and benzene-normal-butyl alcohol. 
—E. Darmois: The action of molybdic acid on the 
rotatory power of the tartaric and malic esters. 
An account of the changes in rotatory power pro- 
duced by the action of aqueous solutions of molybdic 
acid and alkaline molybdates on methyl tartrate 
and ethyl malate.—Victor Henri: The production 
of narrow bands and wide bands in the absorption 
spectra of bodies in solution and in the state of 
vapour. A study of the conditions under which a 
modification of the structure of an organic substance 
causes the change from a line absorption spectrum 
to a band spectrum. For molecules containing only 
one double linkage, the first postulate of Bohr does 
not apply and the second postulate alone holds ; 
for molecules with two neighbouring double bonds, 
both postulates apply, the first being determined by 
the existence of an electric polarity in the molecule. 
—M. Sauvageot and H. Delmas: Tempering extra 
soft steel at a very high temperature. A mild steel 
containing 0-09 per cent. of carbon was tempered 
in water, starting with temperatures from 950° C. 

