384 
NATURE 
|AucusT 17, 1899 
theory of the Wehnelt interrupter. Between the period T and 
the E.M.F. E he obtains the relation 
B 
T=At+ a 
which is closely borne out by experiment.—Magnetic properties 
of the elements, by S. Meyer. The author attempts to connect 
the permeabilities of the elements in the pure state with their 
atomic weight. When arranged in periodic series, the para- 
magnetic elements are seen to group themselves in the centre, 
and the diamagnetic elements at the ends. The scheme is at 
present very rough, owing to the difficulty of determining the 
permeabilities of the rare elements.—Transverse tones of 
caoutchouc threads, by V. von Lang. When caoutchouc threads 
are stretched, the pitch of the note emitted by them remains 
constant between certain lengths, owing to the fact that the 
ratio of length to tension is constant. The author investigates 
how far Taylor’s formula applies to such threads.—Accurate 
control of the frequency of an alternating current, by J. Zenneck. 
The alternate current is made to produce a rotary field, to which 
the kathode beam in a Braun tube is exposed. The end of the 
beam describes a circle on the screen, which is interrupted by a 
tuning-fork twice during every revolution. As long as the 
dots thus produced are on the same diameter the frequency is 
constant. 
SOCIETIES AND ACADEMIES. 
PARIS. 
Academy of Sciences, August 7.—M. Maurice Lévy 
in the chair.—On rolling motion ;. equations of motion 
analogous to those of Lagrange, by M. Appell. The La- 
grange equations cannot be applied without modification to 
those dynamical problems in which the relations between 
the solid bodies are such that they are allowed to roll or 
are pivoted on each other. In a system of three independent 
parameters 7), Jo, 73, the equations of motion are reduced to the 
form ~~ = Qj, where Q, is a function of the forces to which 
1 
the bodies are submitted, and S = 43], J being the acceler- 
ation of the point 7.—Thermochemical determinations : ethy- 
lenediamine, by M. Berthelot. Measurements are given for the 
heats of combustion and formation of cholalic acid, amygdalin, 
conicine, and ethylenediamine.—On ammoniacal silver nitrate, 
by MM. Berthelot and Delépine. A thermochemical study 
of the action of ammonia solution upon a solution of 
silver nitrate. The oxide of silver-ammonium is shown to 
be an alkali, with a heat of neutralisation comparable with those 
of the most energetic mineral alkalis. —On the expansion of iron 
and steel at high temperatures, by M. H. Le Chatelier. The 
table of expansions given for soft iron and six specimens of 
steel, at temperatures ranging between o and 700’, shows that 
the differences in the expansions of the various specimens are 
within the limits of experimental error ; up to about 750°, iron 
and steel expand similarly. But above the temperature of mole- 
cular transformation the expansion of the different specimens of 
steel varies very rapidly with the amount of carbon present, an 
increase of carbon from 0°05 to 1°2 per cent. doubling the co- 
efficient of expansion.—Action of chlorine on a mixture of 
silicon, silica, and aluminium, by M. Emile Vigouroux. A good 
yield of pure silicon tetrachloride may be obtained by first 
heating together a mixture of silica (200 gr.) and aluminium 
(100 gr.) to a dull red heat, cooling the mass and 
extracting with acids. The residue, thus freed from aluminium, 
contains from 14 to 22 percent. of silicon, and readily gives 
the pure tetrachloride on treating with chlorine in the usual 
way.—Action of hydrogen phosphide upon copper oxide, 
hydrate and carbonate, by M. E. Rubénovitch. The reaction 
with the oxide is energetic, and takes place according to the 
equation 
5PH, + roCuO = 2P,Cu; + HPO, + 6H,O. 
‘Copper hydrate behaves similarly, if the gas is admitted in 
such small quantities that the temperature of the reaction cannot 
rise to incandescence. With basic copper carbonate the re- 
action is 
5PH 3 + 5CuCO3.Cu(OH). = 2Cu;P, + H3PO, + 5CO, 
+ 11H,0. 
—On the estimation of mannose in admixture with other sugars, 
NO. 1555, VOL. 60] 
by MM. Em. Bourquelot and H. Hérissey. The authors apply 
the property possessed by mannose of giving an insoluble hydr- 
azone in the cold to the estimation of this sugar. The numerous 
test analyses, some on pure mannose, others on mixtures of 
the same with galactose and maltose, are very satisfactory. —On 
some properties of dioxyacetone in respect to its molecular 
aggregation, by M. Gabriel Bertrand. Dioxyacetone appears 
to exist in two forms, one in crystals, having a molecular 
weight 2(C,H,O3), which is practically insoluble in cold 
alcohol, ether, or acetone; the other, formed by simply melting 
the crystals, has the simple formula C,H,Oy, and is very soluble 
in these solvents. Water slowly dissociates the bimolecular form, 
but not so rapidly as to prevent cryoscopic measurements being 
made in confirmation of the above views.—On the variations in 
the production of glycerol during the alcoholic fermentation of 
sugar, by M. J. Laborde.’ In the numerous experimental 
results quoted, the glycerol found varied from 2°5 to 
2°75 grams of glycerine per 100 grams of sugar decomposed. 
The same yeast, living in saccharine media of the 
same concentration of sugar, may give very varying 
amounts of glycerol, the production being in inverse 
proportion to the activity of the yeast. A rise of temperature 
favours an increase in the amount of glycerol.—On the an- 
atomical structure of Vanilla aphylla, by M. Edouard Heckel. 
A comparison of the anatomical characters of the stems of V. 
aphylla and V. phalaenops?s shows such great differences that it 
is impossible to class them together in the same genus. The 
author also points out that the theory adopted by Herbert 
Spencer, in his ‘‘ Principles of Biology,” to explain the formation 
of monocotyledonous stems, is strongly supported by the fact of 
the simultaneous presence in the stem of V. afhyila and the 
leaves of V. phalaenopses of the same cellular elements consti- 
tuting the skin.—The Pzralahy, the india-rubber weed of Mada- 
gascar, by M. Henri Jumelle.—On the external border of the 
Briangonnais between Freyssini¢res and Vars, by MM. W. 
Kilian and E. Haug.—On the pot-holes of the granitic islets of 
the cataract of Assouan, by M. Jean Brunhes. 
CONTENTS. 
ENZyMes . .... eee? s4°) 4s, « "eee 
Calculation by Abacus. ByG.B.M........ 363 
Our Book Shelf :— s 
Groos: ‘‘ Die Spiele der Menschen.”—A. E. T.. . 363 
De Saporta: ‘‘ Physique et Chimie Viticoles”’ . . . 364 
Perrier : ‘‘ Cours Elémentaire de Zoologie” . . . . 364 
Letters to the Editor: — 
Thermometric Scales for Meteorological Use.—J. Y. 
Buchanan, F.R.S. .. sre) (e,2o,_ sOn 
On the Deduction of Increase-Rates from Physical 
and other Tables.—Prof. C. Runge; Prof. J. D. 
Everett, EARS SSaRgegs-).- . «eee 
The So-called ‘‘ Thunder ”-storm.—Prevalence of 
Anticyclones—seMeteon fr . . .. . .)seeenemsoo 
Scoring at Rifle Matches. (Weth Diagrams.)—A. 
Mallock <7) Eee vai age peeves OO 
On Spectrum Series. (//ustrated.) 1. By Sir 
Norman Lockyer, K.C.B., F.R.S. . ae owing 3 fais) 
The Dover Meeting of the British Association. 
By W. H. Pendlebury . eh eis) TO 
Sune West IndianeBulletin. 2) By H. | (ie eneeesya 
Sir Edward Frankland, K.C.B,, F.R.S. .... . 372 
The National Physical Laboratory ....... 373 
Notes SUM: js ofits 
Rt ape: 373 
Our Astronomical Column :— 
Holmes’ Comet, 1899 @ (1892 III.)... . .-. . . . 377 
Motion of Apse Line of aGeminorum .... . . 377 
Mr-| Tebbuttis@ibsenvatorygay-- 1. en NennGUaT: 
Temperatures in Gaseous Nebule. . . . . . Sct SYA 
The Recent Perseid Meteoric Shower. By W. F. 
Denning 2 377 
United States Deep-Sea Exploring Expedition . . 378 
Magneto-Optic Rotation and its Explanation by a 
Gyrostatic System. (J///ustrated.) 1. By Prof. 
Andrew Gray) (URES Mace chs.) 2 nee 7o 
Science Schools and Classes. .......... 381 
Unversity and Educational Intelligence .. . .. 382 
Scientific Serials see meenen iene): . Seen 
Societies and Academicsmyenesiic + . . -iRmennEged 
