May 20, 1920] 



NATURE 



379 



: -presented by the rolling of the plane of the wheel 

 \\ a fixed cone of arbitrary form. The surface-angle 

 1 the cone differs from four right angles by the final 

 iiigular displacement of the wheel. The same angle 

 of rotation is also measured by the solid angle of the 

 reciprocal cone described by the axis of the wheel. 

 This movement is not yet among those that are 

 imiliarly recognised, though it has important prac- 

 ;i al applications. Bodies suspended from a point on 

 .ai axis of symmetry behave in the same way and 

 for the same reason when swung about by move- 

 ments of the point of support. Aeroplane compass- 

 ards in particular (found to keep practically parallel 

 • I the banked floor of the aeroplane under the action 

 'i gravity and lateral acceleration during a turn) 

 would, from inertia alone, and apart from all other 

 sources of control or disturbance, turn with the 

 machine through an angle geometrically calculable 

 from the movement of the aeroplane. — C. G. Darwin : 

 Lagrangian methods for high-speed motion. The 

 general form of the kinetic potential is found for any 

 number of electrically charged particles moving in 

 any field of electric and magnetic force, allowing for 

 the variability of mass with velocity and for the 

 "retardation" of the forces of interaction of the 

 particles. The result is applied to the "problem of 

 two bodies." The relative orbit is a distorted ellipse 

 with moving apse, and there is no simply definable 

 centre of mass for the system. The finiteness of 

 mass of the hydrogen nucleus is found to have abso- 

 lutely no effect on the separation of the doublets in 

 the hydrogen spectrum. — ^H. P. Waran : The effect 

 of a magnetic field on the intensity of spectral lines. 

 The paper discusses the changes observed in the 

 general spectrum and in the intensity of the lines 

 when the source is placed in a magnetic field. In 

 the case of mercury the field brings out a few lines 

 previously faint or absent, and the abnormal behaviour 

 of the line 6152, which is very prominently brought 

 out, is discussed. In the spectrum of the monatomic 

 gases helium and neon mixed with the diatomic gases 

 oxvgen and hydrogen, onlv the monatomic lines are 

 enhanced very much in brightness, and on this view 

 the fact of the lines getting enhanced in the magnetic 

 field is attributed to atomic radiation. The differences 

 in the degrees of enhancement are said to depend on 

 the series to which the lines belong, and the enhanced 

 lines in the sun-spot spectrum are attributed to this 

 effect of the magnetic field known to exist there.^ — 

 C. V. H. Rao and Prof. Baker: Generation of sets 

 of four tetrahedra niutuallv inscril>ed and circum- 

 'icribed. This paper shows how the figure is obtain- 

 able by a generalised process of inversion from a 

 single tetrahedron, and applies the same method to 

 a certain configuration in four dimensions. — S. 

 Pollard : The terni-bv-term integration of an infinite 

 series over an infinite range, and the inversion of the 

 ordof of intPijration in repeated infinite integrals. — 

 S. R. U. Savoor : Rot^itin^ liquid cvlinders. This 

 paper applies th" method followed by Liapounoff, for 

 the rase of ellipsoids, to the consideration of the 

 stabilitv of the so-called pear-shaped cylinder. 



Dublin. 

 Royal Dublin Society, Aoril 27.— Dr. F. E. Hackett 

 in the chair.— Prof. W. K. Adeney and H. G. Becker: 



The rate of solution of atmospheric nitrogen and 



xygen by water (Part iii.). This paper deals with 



Kperiments made witli bodies of quiescent water, the 



•suits of which show that under ordinary conditions 



mixing of the water takes place to such an extent 



that a modification of the formula previously deduced 



can be used to interpret the process. The effect of the 



humiditv of the air above the surface of the water is 



NO. 2638, VOL. 105] 



also dealt with and its influence on the rate of solu- 

 tion indicated.— Dr. J. Reilly and W. J. Hickinbottom : 

 (i) The influence of electrolytic dissociation on the 

 distillation in steam of the volatile fattv acids. 

 Changes in the distillation constants of the fatty acids 

 arc fully accounted for by introducing a correction for 

 electrolytic dissociation. Observations are given on 

 the influence of salts. (2) Some applications of the 

 method of distillation in steam. A survej* of the 

 method, discussing its theoretical and industrial 

 applications, especially in the analysis of butter and 

 other edible fats and oils. 



Paris. 

 Academy of Sciences, April 26.— M. Henri Deslandres 

 in the chair.— A. Haller and R. Cornubert : The con- 

 stitution of the methylethylcyciohexanone prepared by 

 the ethylation of o-methylcycZohexanone. This com- 

 pound is shown to possess an unsymmetrical struc- 

 ture, both the alkyl groups being attached to the 

 same carbon atom in the ring. — H, Douvilli : The 

 origin of the Orbitoids. — A. Blondel : Theorems on 

 the transmission of energy by alternating current 

 analogous with those of Siemens on transmission by 

 continuous current. Criticism of these theorems. — 

 E. Maillet : Some properties of transcendental numbers. 

 — C. Camichel : The permanent state in water reservoirs. 

 — A. Perot : The variation with pressure of the wave- 

 length of the lines of the cyanogen band. — F. Bourion : 

 A method of physico-chemical analysis of commercial 

 chlorobenzenes. By fractional distillation the speci- 

 men is divided into portions each containing only two 

 constituents ; measurements of density serve to deter- 

 mine the composition of each fraction. The accuracy 

 obtained is illustrated by examples. — A. Kling and 

 D. Florentin : The differentiation of masked and 

 apparent sulphuric ions in complex salts. The use of 

 benzidine as a reagent, suggested in a recent paper 

 by P. Job and G. Urbain, was anticipated by the 

 authors in 1914 in a study of solutions of the green 

 chromium sulphate. — V. Auger : The salts of nitroso- 

 j phenylhydroxylamine (cupferron) : uranous salts. 

 Uranic salts are not precipitated by cupferron, and 

 vanadium can be quantitatively precipitated by cup- 

 ferron in the presence of uranium, as was shown by 

 Turner in 1916. If, hov^'ever, by zinc reduction the 

 uranic salts are converted into uranous compounds, 

 the uranium can be precipitated also by cupferron, 

 and under these conditions vanadium and uranium 

 can be successively determined by means of the cup- 

 ferron.— G. Deniges : Iodic acid as a microchemical 

 reagent for calcium, strontium, and barium. A 

 10 per cent, solution of iodic acid forms a good reagent 

 for the microchemical identification of calcium, stron- 

 tium, and barium salts, soluble or insoluble. One 

 milligram of material is sufficient for the purpose. — 

 Ch. Mauguin and L. J. Simon : The action of chlorine, 

 hvpochlorous acid, and cyanogen on cvanamide and 

 its derivatives. — P. Bertrand : Value of the primary 

 rentrinefal metaxvlem of old or primitive plants. — 

 M. Guilliermond : ' The evolution of the chondriome 

 durinjj the formation of the pollen-grains of Lilitwi 

 randidum.— H. Devaux and H.Bouygues: The useful- 

 ness of sodium fluorid<- eniploved as an antiseptic for 

 the nreservation of railway-sleepers. The scarcity of 

 creosote has led railwav companies to trv other anti- 

 seotics for the preservation of wooden sleepers, and, 

 among others, sodium fluoride has been e-^tensivelv 

 used. While there is no doubt as to the efficiency of 

 sodium fluoride as an antiseptic, on account of the 

 ease with which it is extracted by water, it is useless 

 for the nreservation of wood exposed to ram. and 

 especiallv for the case of railway-sleepers.— A. Desgrez 



