


















a * 
R Y 3, 1 923] 
_ Royal Microscopical Society, January 17.—Prof. 
J. Cheshire: The early history of the ae 
the polarising rr het a Aarne: address). 
early history of double tion, from 1660, 
Bartholinus first received imens of spar 
y of Roérford in Iceland, up to 1808, 
a happy chance, made the wonderful 
polarisation by reflection, and the 
of the light thus produced with the re- 
beams given by Iceland Spar, was discussed. 
iculty was considered of explaining double- 
? 
tion on Huygens’ undulatory theory, dis- 
osed of by Fresnel in 1821, who abandoned 
we theory of longitudinal vibrations, and _ sub- 
: yerse ones for them, after having 
oved, with Arago in 1816, that oppositely 
olarised beams do not interfere in the same way 
hat Young had shown beams of ordinary light do. 
he work of Brewster and Biot was referred to, and 
account given of the extraordinary amount of 
done between Malus’s discovery in 1808, and the 
ivention of the Nicol prism in 1828, from which date 
he modern microscope dates. In the early days the 
arising microscope was employed primarily for the 
‘amination of general objects, whereas the applica- 
on of the petrological microscope to the systematic 
idy of rock-sections dates no further back than 
370. Various forms of polariscopes, including a 
emarkable one invented by Airy in 1831, were 
escribed, and possibilities of further improvements 
iscussed. It was eeged that the work of Herapath 
ind others in the production of artificial tourmalines 
uld be in taken up. Finally, to meet the 
ent difficulties of supplying students’ microscopes 
f was urged that teachers and manufacturers should 
he to an agreement as to the simplest possible 
signs with which the students’ work could be done. 
tuted 


























9 
S Paris. 
Academy of Sciences, January 8.—M. Albin Haller 
the chair.—A. Haller and R. Lucas: Study of the 
sorption in the ultra-violet of a series of derivatives 
‘camphor. Certain derivatives of camphor of the 
Wy CH y, Cogn .R 
“Nco 
ical properties (dispersion, molecular refraction, 
tory power) compared with the corresponding 
tion products. Seven substances of the first 
and two of the second have been studied from 
point of view of their ultra-violet absorption 
ctra, and the results given in the form of the 
rves suggested by Lord Rayleigh.—P. A. Dangeard 
ierre Dangeard: The vitality of Aucuba leaves 
served in a vacuum. An adult leaf of Aucuba 
ced in a vacuum and exposed to light during six 
h ed all its cells alive, and no important 
nce could be detected between the structure of 
e cells and that of the leaves remaining on the 
—Th. Anghelutza: The representation of func- 
ms of one real variable—Gaston Julia: Rational 
ibstitutions with two variables.—J. F. Ritt : Rational 
mutable functions.—G. V. Pfeiffer: A special 
ethod of integration of partial differential equations 
the first order.—Torsten Carleman: The effective 
culation of a quasi-analytical function, the differ- 
at a point being given.—Emile Borel: Re- 
ts on the preceding note of M. Torsten Carleman. 
Dienes: Transfinite series of real numbers.— 
Wazewski: Measurable ensembles.—G. Bratu : 
irves defined by recurrent series.—J. Chuard : Some 
perties of cubical networks traced on a sphere.— 
id Wolkowitsch : The infinitely small movements 
a point of an elastic body admitting a plane of 
F NO. 2779, VOL. 111] 
’ 
show anomalies in their 
40) 
NATURE 
‘The action of heat on kaolins, clays, etc. 
171 
symmetry. Charles Frémont: The influence of the 
velocity of impact in the calibration of dynamometer 
springs. The experiments were lenge ot with falling 
weights so chosen that the product of the weight by 
the height fallen remained constant. The deflections 
of the spiral spring increased as the velocity of impact 
diminished : the anomalous result is due to the inertia 
of the spring.—J. Guillaume: Observations of the 
sun made at the Observatory of Lyons during the 
third quarter of 1922.—R. Lucas: Natural and 
magnetic rotatory power. If a substance possessing 
natural optical activity is suitably placed in a mag- 
netic field, the substance acquires a complex rotatory 
power. The question as to whether there is simple 
additivity of the two rotatory powers, or whether the 
two phenomena exert a mutual influence on each 
other is investigated mathematically, and the con- 
clusion is arrived at that the change in the natural 
rotatory power produced by the action of the mag- 
netic field would be too small to put in evidence 
éxperimentally.—A. Catalan: The structure of the 
arc spectra of the elements of columns VI and VII of 
the periodic table—G. Reboul and P. Blet: The 
different aspects of the electrical discharge in crystals. 
—A. Grumbach: Batteries with fluorescent liquid. 
If two platinum electrodes dip into a fluorescent 
solution and one of them is illuminated, an electro- 
motive force is produced which varies with time. 
Some experimental results with solutions of uranine 
in water are given proving that Goldmann’s explana- 
tion of the phenomenon is inadequate.—A. Bigot: 
Ceramic 
plastic materials, under the action of heat, harden 
without dehydration and without change of volume. 
The colloidal plasticity is reduced by this heating. 
Roger G. Boussu: A method for studying the velocity 
of formation of precipitates——F. Bourion: The 
normal acids of Berthelot and the theory of ions.— 
Henri Bénard and Albert Laborde: The estimation 
of albumen by nephelemetric methods.—Mlle. S. 
Veil: The evolution of the molecule of ferric- 
hydroxide in water: the dehydration of ferric- 
hydroxide by ignition or by heating with water in 
sealed tubes to temperatures between 120° C. and 
210° C. has been co-ordinated with the changes pro- 
duced in the magnetisation coefficient—B. Bogitch : 
The removal of sulphur from metals by lime. A study 
of the decomposition by lime, in the presence of 
carbon, of some metallic sulphides dissolved in the 
fused metal. Copper, nickel, iron, and manganese 
were studied, the action of lime and basic slag 
being examined separately. A mixture of lime and 
fluorspar gave the best results.—Mlle. de la Paulle: 
The estimation of potash as alum.—R. Douris and G. 
Beytout : The mercuric compounds of hexamethylene- 
tetramine.—Carl Stormer: Results of the photo- 
grammetric measurements of the aurora borealis of 
March 22-23, 1920. The greatest altitude measured 
was 750 kilometres ; in no case was the height less 
than too kilometres.—Octave Mengel: New seismo- 
tectonic views, resulting from the earthquakes felt 
between August and December 1922, in the eastern 
part of the Pyrenees.—M. Stefanescu: The growth 
in two opposite directions, and the marks of friction 
and pressure, of the molars of mastodons and elephants. 
—L. Joleaud: Sub-fossil hippopotami of Madagascar 
and the recent geographical connexions of this island 
with the African continent.—Albert Baldit: The un- 
dulatory movements of the atmosphere and their 
utilisation in aviation without a motor.—Jean 
Mascart: The quantity of heat received by the earth 
in the course of the seasons.—F. Diénert : Considera- 
tions on the formation of springs.—J. Cluzet and A. 
Chevallier : The use of thorium emanation in inhala- 
tion. By utilising radiothorium from the sludge 

