April 6, 191 1] 



NATURE 



201 



by stretching also produced definite changes in the value 

 of the constants. — J. B. Ritchie : An apparatus for in- 

 ducing fatigue in wires by means of repeated extensional 

 and rotational strains, with the effects produced by such 

 fatigue on the laws of torsional oscillations. The 

 apparatus, designed by Prof. Peddie, is primarily an 

 oscillating pendulum of large moment of inertia electrically 

 maintained, and is provided with an automatic contact 

 breaker. Rotational fatigue was found to have no effect 

 upon the constants in the oscillation equation for brass 

 wire. — Dr. Thomas Muir : Boole's unisignant. 



MANCHt&TER. 



Literary and Philosophical Society, March 7. — Mr. 

 Francis Jones, president, in the chair. — Prof. E. Ruther- 

 ford : The scattering of the a and ;8 rays and the struc- 

 ture of the atom. From a consideration of general results 

 on scattering by different materials, the central charge of 

 the atom is found to be very nearly proportional to its 

 atomic weight. The exact value of the central charge has 

 not been determined, but for an atom of gold it corre- 

 sponds to about 100 unit charges. From a comparison of 

 the theories of large and small scattering, it is concluded 

 that the effects are mainly controlled by the large scatter- 

 ing, especially when the fraction of the number of particles 

 scattered through considerable angles is small. The results 

 obtained by Crowther are for the most part explained by 

 this theory of large scattering, although no doubt they are 

 to a certain extent influenced by small scattering. It is 

 concluded that for different materials the fraction of 

 particles scattered through a large angle is proportional to 

 NA", where N is the number of atoms per unit volume 

 and A the atomic weight of the material. The main 

 results of large scattering are independent of whether the 

 central charge is positive or negative. It has not yet 

 been found possible to settle this question of sign with 

 certainty. This theory has been found useful in explain- 

 ing a number of results connected with the scattering and 

 absorption of a and )3 particles by matter. The main 

 deductions from the theory are at present under examina- 

 tion, in the case of the a rays, by Dr. Geigcr, using the 

 scintillation method. — ^Dr. H. Geig^er : The large scatter- 

 ing of the a particles. Geiger and Marsden have shown 

 that a small fraction of the o particles incident on a thin 

 film of matter are so scattered that they emerge again on 

 the side of incidence. In the present paper the fraction 

 of the o particles scattered through various large angles 

 ' by a thin gold foil has been experimentally determined by 

 the scintillation method. Radium emanation enclosed in 

 :i fine glass tube was used as a source. The microscope 

 to which the zinc sulphide screen was attached moved 

 round the arc of a circle ; the distance between the scatter- 

 ' ing material and the screen was constant and equal to 

 i about 2 cm. The source of radiation, the scattering foil, 

 I and the screen were enclosed in a metal vessel, which was 

 I exhausted to a low pressure. The number of o particles 

 I scattered through large angles up to 150° was first 

 measured, and, as the emanation decayed, the number of 

 small angles was successively determined. The number 

 of scattered particles per unit area varied, when corrected 

 for decay, nearly 300 times over the range of angles 

 examined. The actual numbers of particles observed 

 varied very approximately as cosec*0/2, where is the 

 angle of deflection. This is the relation theoretically 

 deduced by Prof. Rutherford in the foregoing paper. 

 — R. F. Gvtfyther : Can the parts of a heavy body be 

 supported by their elastic reactions only? 

 Paris. 

 Academy of Sciences, March 27. — M. Armand Gautier in 

 the chair.- — The president announced the death of S. 

 Arloing, correspondant in the sectron of rural economy. 

 • — \. Lacroix : The pcridotites of New Caledonia. — A. 

 Miintz and E. Laine : The nitrogen losses during the 

 purification of sewage by bacterial beds. It has been 

 shown in previous papers that the nitrogen losses average 

 50 to 60 per cent. The present note deals with the forms 

 in which the nitrogen escapes. If organic matter is 

 absent and the nitrogen is present as ammonia salt, no loss 

 occurs, but the losses increase with the proportion of 

 organic matter present. It has been found that tlie nitrates 

 are reduced to gaseous nitrogen.— Pierre Ternnior : «The 

 mylonites of the island of Elba. The existence of these 



NO. 2162, VOL. 86] 



rocks in Elba points to a general and intense crushing 

 action, and leads to a new interpretation of the structure 

 of the island.— J. Carpentier : A tension meter, for 

 measuring the pull exerted by metallic wires in aeroplanes. 



C. Guichard : The C networks, such that the lines of 



a series should be plane curves. — F. Gonnessiat : 

 D'Arrest's comet. A discussion as to the cause of the in- 

 crease of intensity of luminosity over that calculated accord- 

 ing to the law of inverse squares. — Henri Lebesgue : The 

 invariance of the number of dimensions of a space and 

 on Jordan's theorem relating to closed varieties.— Georges 

 L6ry : Green's function for an algebraic contour.— 

 Maurice Frechet : The notion of a differential.-— Andr6 

 Broca : The constitution of axes of rotation sufficiently 

 stable to permit the measurement of the geodesic angles 

 by the method of repetition.— F^lix Michaud : The causes 

 which may produce the variation, at constant temperature, 

 of the vapour pressure of a liquid. The curvature of 

 the meniscus is not the direct cause of the capillary varia- 

 tion of vapour pressure.— E. Henriot : The radiations of 

 the alkaline metals. Potassium salts emit a very penetra- 

 ting ionising radiation, that from rubidium salts being 

 less penetrating but more intense. Caesium salts give no 

 appreciable ionisation, an unexpected result. The causes 

 of the marked differences between the radiation of the 

 metals and their salts is discussed.— A. Leduc : Applica- 

 tion of principles to a case of magnetostriction.— 

 M. de BroKlie and L. Brizard : The mobility of the 

 ions produced in- air by the hydration of sulphate of 

 quinine. The ionisation of air produced by this salt 

 belongs to the type of rapid recombination, and the 

 measurement of the mobility of these ions presents special 

 difficulties. The present note describes how these difficul- 

 ties have been overcome. — Maurice Joiy : A static means 

 of tripling the frequency of alternating currents.— Maurice 

 Coste : The metallography of the gold-tellurium system. 

 Details are given of the methods adopted for purifying the 

 tellurium and preparing the alloys. Only one compound 

 appears to be formed, AuTe^, and there is direct evidence 

 against the formation of the compound Au.Te of Mar- 

 gottet. — P. Pascal : Magneto-chemical researches on the 

 atomic structure of the halogens. — Ath. I. Soflano- 

 poulos : Two new compounds of stannous chloride with 

 ammonia.— E. Dumesnil : The preparation of an arsenic 

 amalgam. Arsenic amalgam is obtained by reducing a 

 solution of arsenious acid and mercury bichloride in hvdro- 

 chloric acid by sodium hypophosphite. The composition 

 of the amalgam corresponded to As.Hgj.- Alexandre 

 Hubert : The pyrogenous decomposition of the metallic 

 xanthates. Eleven metallic xanthates have been examined, 

 and a table is given showing the nature and amount of 

 the gaseous and liquid products. The canthates of nickel 

 and mercury give the ester C.H^O.CS.SC.H, in good 

 yields.— L60 Vignon : The action of water vapour upon 

 carbon in presence of lime. The principal gaseous pro- 

 ducts are hydrogen and methane, together with carbon mon- 

 oxide and dioxide, oxygen, and nitrogen.— Paul Lebeau : 

 Some definite bismuthides. Remarks on a recent paper 

 by A. G. Vournasos on a method of preparing stxlium 

 bismuthide.— L. Hackspill and R. Bossuet : The 

 temperature at which water is attacked by the alkaline 

 metals. The globule of the metal, previously distilled in 

 a vacuum, and with a perfectly bright surface, is cooled 

 to a given temperature, and water vapour allowed to con- 

 dense on the metal ; the alteration of pressure caused by 

 the evolution of hydrogen indicates the reaction. Caesium 

 is attacked at -ii6° C, rubidium at -108°, potassium 

 at -105°, and sodium at -98°. It would appear that the 

 reaction is between metal and vapour, and not metal and 

 solid ice.— Marcel Guichard : The gases given off by the 

 walls of glass, porcelain, and silica tubes. Jena glass 

 gave about 003 c.c. of gas per 100 sq. cm. of surface; 

 with porcelain 'the results were variable, but the quantity 

 was about three times that of the Jena glass. Fused silica 

 gave as much as 2 c.c. of gas per 100 sq. cm. surface.— 

 M. Lespleau : A method of preparing certain true 

 acetylenic alcohols. The method indicated in a previous 

 communication, based on the action of methylmagnesium 

 bromide upon monobromacrolein, has been generalised, 

 and additional acetylenic alcohols are described. — M. 

 Godchot and F. Taboury : The catalytic addition of 

 hydrogen to cyclopentanone. The products of the reaction 



