August 5, 1897] 



NATURE 



335 



SCIENTIFIC SERIALS. 

 Wiedemann' s Annalen der Physik und Chemie, No. 6. — 

 Diffusion constants of some metals in mercury, by G. Meyer. 

 A dilute zinc amalgam was poured into two glass tubes, one of 

 which was closed by fusion at the bottom, while the other was 

 provided with a fine net of platinum wire, which did not allow 

 the amalgam to penetrate. The latter tube was inserted in a 

 beaker containing H2SO4. The two tubes were joined by a 

 siphon. On passing a current through, with a kathode of 

 platinum immersed in the beaker, the lowest layer of amalgam 

 next the net was deprived of zinc and reduced to the state of 

 pure mercury. The concentration of the top layer was estimated 

 by the E.M.F. between the two tubes, and the rate of fall of 

 the concentration was used to determine the diffusion constant 

 of the zinc in the mercury. It was found to be o'o87 in cm.- 

 hours for zinc, 0*065 fo"" cadmium, and 0*057 for lead. — Electric 

 vibrations in the Lecher system, by R. Apt. The author 

 investigates the influence of the primary exciter in a Lecher 

 wire system upon the form and intensity of the oscillations. 

 There are nodes at the bridges over the secondary wires and at 

 the spark gap. A maximum of intensity is obtained when the 

 divisions of the secondary circuit are in resonance amongst them- 

 selves, and with the two divisions into which the primary system 

 is divided by the spark gap. If the spark passes in a gas, the 

 intensity varies directly with the pressure. — Kathode and 

 Rontgen rays, by J. Precht. Goldstein's "canal rays," pro- 

 duced by perforating the kathode, are kathode rays which are 

 not deflected by the magnet. They are distinguished from 

 Rontgen rays by the absence of photographic and fluorescent 

 actions. Rontgen rays have a condensing effect upon water 

 vapour, and they increase the resistance of a selenium cell by 32 

 per cent. A portion of the rays proceeding from discharge tubes 

 is not a wave motion, since the extent of absorption of the 

 Rontgen rays by paper depends upon the duration of the radia- 

 tion. Perhaps this part of the action is of a purely electrical 

 nature. Rontgen rays show distinct interference phenomena, 

 and are therefore partly due to some kind of wave motion. — 

 Measurements of the interference of direct X-rays and others 

 reflected at grazing incidence gave wave-lengths of 370 to 830 

 (xy^. These are near the limits of the visible spectrum, and since 

 these rays are practically invisible they are probably longitudinal 

 for the most part. — Arc lamps with amalgam terminals, by E. 

 Gumlich. Arons has constructed an arc lamp in which the 

 electrodes consist of mercury. If amalgams could be used 

 instead, they might be made to yield an intense spectrum due to 

 the body combined with the mercury. The author took special 

 precautions to avoid oxidation during the filling process, and 

 constructed a successful cadmium amalgam lamp which gives a 

 brilliant red line. To avoid loss of light due to the opaque 

 deposit round the kathode, the electrodes are placed in side 

 tubes, and the light is projected down the main tube by a mirror. 

 No. 7. — Dampingeffectof a magnetic field on rotatinginsulators, 

 by W. Duane and W. Stewart. The phenomena of damping of 

 such bodies as sulphur and paraffin when rotating in a magnetic 

 field, described some time ago by Duane, are, after all, found to be 

 due to traces of iron. This can only be proved, however, by dis- 

 tilling these bodies five times and noting the absence of the 

 damping. The latter will persist even after all chemical 

 reactions have failed to indicate the presence of iron. The 

 damping test is fifty times more delicate than chemical analysis. 

 — Conductivity of carbon for heat and electricity, by L. Cellier. 

 In metals the electric and thermal conductivities have an 

 approximately constant ratio, if the specific heat per unit 

 volume is taken into account. Measurements made with 

 graphite, retort carbon, and various kinds of arc light carbons 

 show that there is no correspondingly simple relation in the 

 case of carbon. Whilst in the case of metals the ratio between 

 the two conductivities varies between 0*07 x io®ando*i2 x 10", 

 it varies between the limits I'S x 10® and 5372 x lo** in the 

 carbons studied. The relation referred to seems, therefore, only 

 to hold good for metals. — Magnetic deflection of kathode rays 

 and its dependence upon the discharge potential, by W. 

 Kaufmann. The extent to which kathode rays are deflected by 

 a magnetic field is usually considered to depend upon the gas, 

 the degree of exhaustion, and the dimensions of the tube. The 

 author claims to have shown that all these conditions are only of 

 secondary importance, and owe their influence exclusively to the 

 fact that they affect the discharge potential between the anode 

 and the kathode. The magnetic deflectibility is inversely 

 proportional to the square root of the difference of potentials. — 



NO. 1449, VOL. 56] 



Determination of the period of electric oscillations, by Margaret 

 E. Maltby. This paper contains the description of a new method 

 for determining the ratio v between the electrostatic and electro- 

 magnetic units. It is based upon the principle of the Wheat- 

 stone bridge. The capacities of the two halves of an electrometer 

 form two branches, and a known capacity and a known resistance 

 form the third and fourth branches respectively. The mean 

 value of three series of measurements was 3 "015 x 10'", which 

 differs from the best results extant by an amount well within 

 the errors of observation. — A relation between the electrical, 

 chemical, and geometrical properties of a crystal, by J. Becken- 

 kamp. The genesis of the electrical poles is connected with the 

 chemical structure of a crystal. This is evidenced by such 

 facts as that in aragonite treated with HCl, and in baryta treated 

 with H2SO4, the directions of greater solubility are opposed to 

 the positive direction of the electrical lines of force. 



SOCIETIES AND ACADEMIES. 

 Edinburgh. 

 Royal Society, July 19.— Lord Kelvin in the chair.— The 

 President presented to the successful Fellows the prizes awarded 

 by the Council, and in a few words described the nature and 

 value of the work done by each.— Mr. J. W. Inglis read an in- 

 teresting popular account of his experience of Indian earth- 

 quakes during a residence in that country of nearly twenty-five 

 years. — Dr. C, G. Knott read a paper on relations among 

 various types of magnetic strains. The first note dealt with the 

 relation between the elongation in iron or nickel in a magnetic 

 field, and the twist produced in the same, when, in addition, an 

 electric current was passed through the material in the direction 

 of the magnetisation. Data recently obtained were used in 

 testing a formula, given by the author in a previous paper 

 (Trans. R.S.E., vol. xxxv., 1888), for the twist in a cylinder 

 under longitudinal and circular magnetising process. The 

 striking characteristics of the twist phenomenon were repro- 

 duced, e.g. the maximum twist in iron occurring in a field lower 

 than the field for maximum elongation, and the maximum twist 

 in nickel, although in this metal there is no maximum or mini- 

 mum point in the elongation-curve. The second note gave an 

 account of experiments elucidating the character of the strain in 

 a nickel tube when magnetised. There was a small but measur- 

 able diminution of volume produced in the material of the tube, 

 and a (comparatively) large apparent diminution of volume 

 indicated in the outer dimensions of the tube, when it was 

 plugged up at both ends. The elongation in the direc- 

 tion of magnetisation having also been measured, the data 

 were used to calculate the radial displacements, usually 

 outwards, of the inner and outer surfaces of the tube. 

 In a tube of external radius 1*39 cm. and internal radius 

 •477 cm. these displacements, in a field of 200, of the corre- 

 sponding surfaces were 9*6 and 1*9, and in a field of 500, 147 

 and 2*3, the unit being lo"" cm. The probable nature of the 

 strain at different parts was considered. — A very interesting 

 paper, giving an account of the expedition from Edinburgh to 

 observe the total eclipse of the sun on August 8, 1896, was read 

 by Prof. Copeland and Mr. Ramsay. — The President then 

 adjourned the meeting till November. 



Dublin. 

 Royal Dublin Society, June 16.— Prof. W. J. Sollas, 

 F.R.S., in the chair. — Mr. J. R. Wigham described a new 

 method of conferring distinguishing characteristics upon illu- 

 minating buoys and beacons for harbours, estuaries, and rivers. 

 — Mr. Richard J. Moss read a paper on the cause of the death 

 of fish in the Flesk River and Killarney Lake during the recent 

 bog-flow in the County of Kerry. — Mr. William Barlow read a 

 paper on a mechanical cause of homegeneity of structure and 

 symmetry geometrically investigated, with special application to 

 crystals and to chemical combination. This paper was com- 

 municated by Prof. W. J. Sollas, F.R.S.— Prof. D. J. Cunning- 

 ham, F.R.S., gave a lantern demonstration of the deep origins 

 of certain of the cranial nerves in the chimpanzee and orang- 

 utan. — The following paper was omitted from the list of those 

 read at the meeting of May 19 : A spectrographic analysis of 

 iron meteorites, siderolites, and meteoric stones, by Prof. W. 

 Noel Hartley, F.R.S., and Mr. Hugh Ramage. 



