Juty 1, 1915] 
NATURE 501 

ties (both morphological and physical) obey the law 
of progression with the atomic weight of the alkali 
metal which has been established in previous com- | 
munications. This law is particularly well illustrated 
by the fact, to which no exceptions have been observed, 
that average change of angle between crystal faces, 
and also maximum change of interfacial angle (which 
exceeds two whole degrees), are directly proportional 
to change in atomic. weight when any one alkali 
metal is replaced by another. (2) The dimensions of 
the space-lattice of any ammonium salt of the series 
are nearly identical with those of the intermediate 
rubidium salt, so that the two atoms of rubidium are 
replaced by the ten atoms of the 2NH, radicle-groups 
without appreciably altering the crystallographic 
structural dimensions. (3) The salts of the series in 
which R is thallium (also studied in a previous memoir) 
resemble the ammonium salts closely, in truly belong- 
ing to the isomorphous series, but not to the more 
exclusive eutropic series formed by the salts of 
potassium, rubidium, and cesium. Like the ammo- 
nium salts, they also closely resemble the rubidium 
salts, but the thallium salts are distinguished optically, 
possessing transcendent refractive power, both their 
refractive indices and their molecular refraction being 
far higher than for any other salts of the whole iso- 
morphous_ series.—E. B. R. Prideaux: General 
equations for the neutralisation’ of dibasic acids, and 
their use to calculate the acidity of dilute carbonate 
solutions.—Prof. H. A. Wilson: The electrical con- 
ductivity and luminosity of flames containing salt 
vapours.—T. R. Merton: A spectrum associated with 
carbon in relation to the Wolf-Rayet stars.—Sir Wm. 
Abney and Prof. W. Watson: The threshold of vision 
for different coloured lights.—Lord Rayleigh: THydro- 
dynamical problems suggested by Pitot’s tubes.— 
Prof. M. C. Potter: Electrical effects accompanying 
the decomposition of organic compounds. II.— 
Ionisation of the gases produced during fermentation. 
—Prof. E. W. MacBride and A. Jackson; The inherit- 
ance of colour in the stick-insect (Carausius morosus). 
—Sir Francis Darwin: The relation between transpira- 
tion and stomatal aperture.—D. M. S. Watson: The 
monotreme skull—a _ contribution to mammalian 
morphogenesis. 
Mineralogical Society, June 15.—Dr. A. E. H. 
Tutton, president, in the chair.—G. M. Davies: 
Detrital andalusite in Cretaceous and Eocene sands. 
Detrital andalusite is not confined to Pliocene and 
later deposits as was formerly supposed, but is a 
frequent constituent throughout the Cretaceous and 
Eocene beds of the south-east of England. In the 
lower Cretaceous beds it is still perfectly fresh, and 
shows no signs of instability under the influence of 
meteoric water.—J. F. N. Green: The garnets and 
strealxy rocks of the English Lake District. Certain 
peculiar rocks occurring in the Lake District are char- 
acterised by almandine garnets and parallel streaks 
of secondary minerals. ‘The capricious distribution of 
the garnets in diverse rock-types was considered to 
exclude originality, and thermal or dynamic altera- 
tions were shown to be inadequate. Circulating solu- 
tions under pressure during the solfataric stage of the 
Borrowdale episode were suggested as the agent, and 
illustrations were given of the replacement of felspar 
by garnet in Lake District rocks. The same origin 
was assigned to the streaky infiltrations which fre- 
quently contain pyrites or garnet.—Dr. S. Kozu: The | 
errors in the angle of the optic axes resulting from 
those of the principal refraction indices determined by 
total reflection. The indices so found are correct 
within 0-o002 for sodium light. Assuming the error to 
be only half this, the extreme values of the angle are 
for anorthite, 76° 8-6’, and 79° 21-8’; for albite, 76° 
NO. 2383, VOL. 95| 

141’ and 80° 46-9'; and adularia 56° 16-9) and 65° 
56-9'.—Dr. S. Kozu: The influence of temperature on 
the optic axial angle of sanidine from the Eifel. 
Pockels has shown that in those rhombic crystals in 
which the axial angle varies considerably in the 
| neighbourhood of zero the relations between the angle 
and the temperature is represented by a parabola. 
Sanidine from the Eifel very nearly approaches the 
conditions of a rhombic crystal. The values of 2E 
were determined for seven different wave-lengths. The 
plotted curves were found to accord with Pockels’s 
statement; further, the complex curves for the various 
wave-lengths were identical—Dr. G,. T. Prior: The 
meteoric stones of Warbreccan, Queensland. Three 
stones, weighing respectively about 69, 64, and 1 Ib., 
were known to the natives of central Queensland 
before 1904, and their fall was probably seen. They 
were acquired by the British Museum in 1905. They 
are white-veined chondrites, and in chemical and 
mineral composition are similar to other members of 
the group.—A. F. Hallimond: Autunite. It is con- 
cluded that the Cornish material is essentially different 
from the Autun mineral, and the name bassetite is 
proposed for the former, the fundamental characters 
of which are:—Oblique, B=89° 17’, a@:b:c= 
0:3473 1 1:03456; forms, o10, I10, 120, OI, III, 
121, 121,141,101; twinning by parallel growth of aand 
c axes, perfect cleavage parallel to o10, also 100, 001; 
yellow, transparent; biaxial, 2E= 110° ; pleochroic, pale 
to deep yellow; soluble in acids. 
Linnean Society, June 17.—Prof. E. B. Poulton, 
president, in the chair.—The four following papers 
were reports on materials brought home by Prof. J. 
Stanley Gardiner from the expedition to the Indian 
Ocean in H.M.S. Sealark in 1905 :—E. T. Browne: 
Meduse from the Indian Ocean.—Prof. A. Dendy : 
(1) Report on the Hexactinellid sponges (Triaxonida) ; 
(2) Continuation (Tetraxonida).—J. C. Robson: The 
Cephalopoda obtained. 
Paris. 
Academy of Sciences, June 21.—M. Ed. Perrier in the 
chair.—J. Boussinesq : The extreme slowness of cooling 
in the deep parts of the earth’s crust, and an attempt 
to estimate, starting from a certain period, the pro- 
gress of the solidification.—Paul Briick : Observations 
of the Mellish comet (19154) made at the Observatory 
of Besancon with the 33 cm. equatorial. Eleven posi- 
tions of the comet are given for March 16, April 13, 
15, 16, 17, May 14 and r5.—René Garnier : The repre- 
sentations of the integrals of the equations of M. Pain- 
levé by means of the theory of linear equations.—M. de 
Broglie: The spectra of the homogeneous secondary 
X-rays. A claim for priority as regards a recent paper 
on the same subject by M. Glagolev.—E. Raverot: A 
temperature interval regarded in relation to mechanical 
measurements. Starting with the numerical coinci- 
dence that the erg is 0:2381 x 1077 calories, and the 
specific heat of air at constant pressure is 0:2382 
calories, the joule (0-238 cal.) is defined as the quantity 
of calorific energy corresponding to a variation of 
volume of the mass of 1 gram of air of 1/273 of its 
volume at 0° C., at the constant pressure of the atmo- 
sphere.—Léon Bouthillon: The charge of condensers 
by means of a constant electromotive force and their 
discharge in a spark circuit. Whatever may be the 
kind of spark-gap employed, the conditions under 
which a musical note is produced are the stable con- 
ditions under which the system is self-regulating. 
—G. A. Le Roy: The measurement of the waterproof 
qualities of cloths and military fabrics. The percolat- 
ing water falls on a dry filter paper impregnated with 
a salt, and establishes an electrical circuit. The 
apparatus can be made recording, and does not re- 
