November 25, 1909J 



NA TURE 



119 



especially marked when the mass of an ion is much greater 

 than that of a molecule of the gas through which the ion 

 is moving, methods founded on the conception of the free 

 path are not suited for the calculation of the velocities of 

 the ions. If we suppose that the operative forces acting 

 between the ions are such as exist between a charged 

 body and a conducting sphere, the force between the ions 

 and the molecules would, except close to the molecules, 

 be proportional to the inverse fifth power of the distance, 

 and we can apply Maxwell's results to this case, making 

 the slight alterations which are necessary when the force 

 is an attraction instead of a repulsion, as in Maxwell's 

 investigation. The expressions deduced in this way for 

 the mobility are such that, considered as a function of M, 

 the mass of the ion, and m, the mass of a molecule of the 



gas, the mobility varies as-f' "^ ■^, and thus, when M 



I. M J 

 is large compared with m, varies very slowly with the 

 mass of the ion. The diffusion of the emanations of radio- 

 active substances through air or other gases would, since 

 the molecules of the emanation carry electrical charges, 

 follow the same law, so that the rate of diffusion of the 

 emanation would only vary very slowly with the atomic 

 weight ; thus we cannot attach much importance to deter- 

 minations of the atomic weight of the emanation made by 

 observing their rate of diffusion through other gases. 



Manchester. 



Literary and Philosophical Society, November 2. 

 — Mr. Francis Jones, president, in the chair. — ■ 

 T. G. B. Osborn : A note on the staminal mechanism 

 of Passiflora coerulea. The paper contained a record of 

 observations made during the summer of this year on 

 Passiflora coerulea, and directed attention to three 

 staminal movements which occur in the order in which 

 they are given below, viz. : — (i) A radial movement of the 

 anthers on the filament of 180°, which occurs as soon as 

 the flower opens. (2) A second movement of the anther 

 through 90° into a plane at right angles to the first, i.e. 

 into the tangential plane, in which position a special 

 mechanism is called into play to retain it there. (3) The 

 radial movement, in two stages, of the stamen as a whole, 

 so as to bring it from an erect to a drooping position, the 

 first stage of this movement being in part cortcurrent with 

 (2), and coextensive with the first stage of anthesis. — 

 D. M. S. Watson : A preliminary note on two new genera 

 of Upper Liassic Plesiosaurs. The Manchester Museum 

 contains two important skeletons of Plesiosauriis homalo- 

 spondylus, Owen, which show that the pectoral girdle does 

 not conform to the type of that of Plesiosaurus, but is 

 elasmosaurian, resembling that of Cryptocleidus. The 

 coracoids are narrow ; the scapulae meet in the middle line 

 and pass back as a bar to join the coracoids. The clavi- 

 cular arch is reduced, lying on the visceral surface of the 

 anterior plates of the scapulse. There is no interclavicle. 

 A new genus, Microcleidus, is founded for the species. 

 Another skeleton, lacking the head, also in the Manchester 

 Museum, is made the type of the new genus and species 

 Sthenarosaurus dawkinsi. The genus is remarkable for 

 the smallness of the coracoids and the strong clavicular 

 arch, which resembles that of Thaumatosaurus, as deter- 

 mined by Lydekker, but has a posterior process in the 

 centre. 



November 16. — Mr. Francis Jones, president, in the chair. 

 — C. E. Stromeyer : Relative periods of revolution of 

 planets and satellites. The author pointed out that, if the 

 solar system has been built up out of meteorites, certain 

 relations as regards periods of revolution should exist both 

 amongst the planets and their satellites. The periods, not 

 only of the planets, but also of their satellites, should be 

 expected to stand in the ratios i, 2, 4, 8, &c., or i, 3/2, 

 2, 3, 4, &c. The first of these series is well represented 

 by Jupiter's satellites, I., II., and III. of which stand 

 in the exact ratio of 4, 8, 16; V. has a period of 11, 

 IV. has a period of 37S instead of 32, and VI. and VII. 

 combined have a period of 576, or little more than 512, 

 which would be the tenth term of the series. The outer- 

 most satellite, the exact period of which has not yet been 

 determined, should, if the above rule holds good, have a 

 period of twice 260 days, say one and a half years. 

 Saturn's satellites agree with the second series, which 

 NO. 2091, VOL. 82] 



includes thirds. The mean periods of the several pairs 

 are i, 2, 3-96, — , 16-5, — , 681. — F. Nicholson ; Some 

 early correspondence between Mrs. Hemans and Mr. 

 Matthew Nicholson, a former member of the society. 

 Paris. 

 Academy of Sciences, November 15. — M. Bouchard in 

 the chair. — G. Darboux : Congruences of curves. — M. 

 Gouy : The vapour pressure of an electrified liquid. The 

 total effect, at least for hquids having a high specific 

 inductive capacity, is for an electric field to increase the 

 vapour pressure. The dielectric polarisation, when the 

 field is normal to the surface, produces an increase in the 

 vapour pressure ; the increase of the ions in the surface 

 layer of the electrolyte diminishes the vapour pressure, and 

 the net result is the difference of these two effects. — M. 

 de Forcrand : The acid carbonates of the alkalies. — 

 Edouard Meckel : The influence of anaesthetics and frost 

 on plants containing coumarin. Plasmolysis is produced 

 by the action of chloroform, ether, or by cold, the 

 coumarin being immediately given oft'.- Edouard Meckel : 

 Fixation of the cultural bud-formation of Solatium maglia. 

 — M. Idrac : Ocular and photographic observations of the 

 planet .Mars. An account of observations made at the 

 Meudon Observatory with the large double telescope during 

 the recent opposition of Mars. In some instances details 

 were shown on the photographs which could not be 

 observed by simultaneous eye observations. — E. M. 

 Antoniadi : Observations of the planet Mars made at the 

 Observatory of Meudon. A map of the planet, on 

 Mercator's projection, is given, summarising observations 

 made between September 20 and November 9. — A. de la 

 Baume Pluvinel and F. Baldet : The photography of 

 the planet Mars. An account of work done with the new 

 equatorial at the astronomical station on the Pic du Midi. 

 — N. E. Norland : Equations of finite differences. — G. A. 

 Miller : Groups produced by two operators, each of which 

 transforms the square of the other into its inverse. — 

 ."Mbert Grumbach : Contact electrification. A study of 

 the electromotive forces produced by the filtration of solu- 

 tions of potassium chloride, with and without an added 

 non-electrolyte (phenol). — Vasilesco Karpen : Telephony at 

 great distances. — .Andr^ Leaute : The destructive effects of 

 oscillating discharges of high frequency. — Gargam de 

 Moncetz : A formula for sensitising plates for the extreme 

 red, commencing with the infra-red. The solutions given, 

 used on silver iodobromide plates, enable lines up to the 

 calcium line X 860 to be photographed. — Paul Gaubert : 

 A new highlv fluorescent substance derived from physo- 

 stigmine. Phvsostigmine in aqueous solution is allowed 

 to stand for several months until it has acquired a deep 

 blue colour, and to this phthalic acid is added. The sub- 

 stance produced forms deep blue crystals, which in solu- 

 tion are intensely fluorescent. — W. Broniew/ski : The 

 electrical properties of the aluminium-copper alloys. 

 Twenty alloys of aluminium and copper were prepared. 

 The measurements made on these included the electrical 

 conductivity at 0° C, the temperature coefficient of the 

 resistance, the electromotive force against carbon in a 

 solution of ammonium chloride, and the thermoelectric 

 power. The results are given both in tabular and graphical 

 form. In addition to the definite compounds of aluminium 

 and copper already known, the existence of Al,Cu, has 

 been brought out by these experiments. — Georges Meslin : 

 The magnetic properties of liquids constituted by siderose. 

 .Aniline or carbon bisulphide containing powdered siderose 

 in suspension exhibit the phenomenon of magnetic 

 dichroism to an extent much greater than with any sub- 

 stances previously examined. — .^bel Buguet : The cryo- 

 scopy of organic mixtures and addition compounds. An 

 account of the cryoscopic study of mixtures of acenaph- 

 thene and phenanthrene with two nitrotoluenes. — H. 

 Baubigny : The action of heat and light on silver sulphite 

 and the double alkaline sulphites. The determination of 

 the yield of dithionic acid. — V. Auerer : The mixed halogen 

 stannic compounds. The bromindide SnBr.I, was sub- 

 mitted to a series of slow crystallisations, and the ratio 

 of iodine to bromine found to vary. The study of the 

 cooling curve of the supposed SnBrJ, showed that this 

 also behaved as a mixture. — P. J. Tarbouriech ; The 

 dehydration of oxycyclohexvldimethylcarbinol. — M. Deprat : 

 The eruptive and metamorphic formations of Tonkin, and 



