778 



NA TURE 



[November 24, 1923 



Societies and Academies. 



London. 



Royal Society, November 15. — Sir William Bragg 

 and G. T. Morgan : Crystal structure and chemical 

 constitution of basic beryllium acetate and propionate. 

 Ba.sic iKTvllium acetate is shown by X-ray analysis 

 to be a highly co-ordinated com|x>und. The molecule 

 is a perfect tetrahedron, having an oxygen at the 

 centre, a ber>'llium alone at each comer, and an 

 acetyl group associated with each edge. The 

 crystalline structure is the same as that of diamond. 

 The propionate forms a monoclinic cr>'stal. The 

 propyl group can no longer be arranged so as to 

 ix)ssess a plane of symmetry, as in the case of the 

 acetyl ; and in conseauence the symmetry Is much 

 less. — G. I. Taylor : Lxpeiiments on the motion of 

 solid bodies in rotating fluids. — L. C. Jackson : In- 

 vestigations on paramagnetism at low temjicratures. 

 Pt. I. Powdered substances. The following para- 

 magnetic substances have been investigated from atmo- 

 spheric temperature down to the lowest tem|)erature 

 obtainable with liquid hydrogen (about 14° K) : 

 anhydrous sulphates, heptahydrated sulphates and 

 ammonium double sulphates of cobalt, nickel, and 

 ferrous iron. These substances follow the Weiss 

 law x(T +A) =C at relatively high temperatures, 

 but at the lowest temperatures, (1) susceptibiUty 

 increases more rapidly with fall in temperature than 

 is given by Weiss law, and (2) the curve of \\x against 

 T possesses a point of inflection ; a maximum and 

 a minimum value of susceptibility occur in the 

 region of lowest temperatures. Pt. II. Crystals. 

 The principal susceptibilities of crystals of cobalt 

 ammonium sulphate and nickel sulphate (hepta- 

 hydrate) have been determined over a temperature 

 range of 290° K down to 14° K. The Curie constant 

 C is same for each of the principal susceptibilities of any 

 crystal. Deviations from the Weiss law in the case of 

 cobalt ammonium sulphate fall into category (i) 

 above, while those of nickel sulphate fall into category 

 (2). — L. C. Jackson and H. Kamerlingh Onnes : 

 The magnetic properties of some paramagnetic 

 double sulphates at low temperatures. The magnetic 

 susceptibilities of powdered cobalt potassium sulphate, 

 cobalt rubidium sulphate, manganese ammonium 

 sulphate, have been measured at temperatures from 

 atmospheric temperature down to about 14° K. 

 The two cobalt compounds confirm the results given 

 above for cobalt ammonium sulphate. Manganese 

 ammonium sulphate obeys the Curie law, xT = const., 

 down to the lowest temperature investigated. This 

 result fits well with the known behaviour of other 

 manganese salts, showing tliat in this series of com- 

 pounds the substance follows Curie's law more 

 closely the greater its " magnetic dilution." — H. H. 

 Potter : Some experiments on the proportionality of 

 mass and weight. The gravitational accelerations 

 of lead, steel, ammonium fluoride, bismuth, paraffin 

 wax, duralumin, and mahogany have been compared 

 with that of brass, and no diflference greater than 

 that attributable to experimental error has been 

 found. An accuracy of one part in 50,000 has been 

 obtained. Special attention has been given to two 

 substances, ammonium fluoride and paraffin wax, 

 which have large hydrogen contents. — Lord Rayleigh : 

 Further studies on the glow of phosphorus and its 

 extinction by moist oxygen. The velocity of blast 

 necessary to blow away the glow of phosphorus 

 increases enormously with rise of temperature. On 

 the other hand it is enormouslv diminished by 

 enriching the air blast with oxygen. In either case 

 the range examined was of order 1000 times. This 



NO. 2821, VOL. I 12] 



velocity of blast measures rate of propagation up- 

 stream of glow through mixture of .phosphorus 

 vapour and oxygen. Where the velocity is reduced, 



by cooling or by adding •- " to less than i 



cm. /sec, the condition of u is approached. 



From this viewjxiint the ki -.imction by moist 



oxygen alone is the limiting case of slow propagation. 

 Hence extinction Ls due to failure of the process 

 causing propagation, probably a catalytic action of 

 products of combustion. Excess oxygen, like other 

 mhibiting substances, " poisons " these products. — 

 H. A. Wilson : An experiment on the origin of the 

 earth's magnetic field, — H. Robinson : The secondary 

 corpuscular rays produced by homogeneous X-ray's. 

 The Kobinson-Rawlinson method of investigatmg 

 velocities of secondary cathode rays produced by 

 X-rays has been developed with the view of increased 

 accuracy. Sp>ecial attention has been paid to homo- 

 geneity of the primary X-ray beam. The velocities 

 of secondary electrons are measured by deflexion in 

 the magnetic field of a pair of large Heir' '* - - -ils. 

 The copper Ka rays are used as primary :.>n. 



Five of the N absorption edges of bismuti. ...^.^ ix:cn 

 measured, the remaining two not being separated 

 from the O rings. All five M edges have been 

 measured for atoms as light as tungsten. The L 

 limits have been measured as far as copper, and the 

 K limits to oxygen. Progressive changes occur 

 along the series of elements in the relative intensities 

 of different members of the same group. — J. W. 

 Gifford, with an introduction by "r. ^^. Lowry : 

 Some refractive indices of benzene and cyclohexane. 

 — J. A. V. Butler : A note on the significance of the 

 electrode potential. A thermodynamical argument 

 given in Heyrovsky's paper on the significance of 

 the electrode potential contains stages of the cycUc 

 process employed which are irreversible ; hence the 

 conclusions are erroneous. When the cyclic pro- 

 cess is conducted reversibly. the sum of the differ- 

 ences of potential round the cycle is zero ; therefore 

 no information regarding the relations between 

 the electrode potentials and the various chemical 

 equiUbrium constants is obtained by the use of 

 a cyclic process of this kind. 



Mineralogical Society, November 6 (Anniversary 

 meeting). — Dr. A. Hutchinson president, in the chair. 

 — L. J. Spencer : Euclase and platinum from diamond- 

 washings in British Guiana. Small disks resembling 

 fossil corals consist of a radial aggregation of euclase 

 crystals so arranged that the plane of sj-mmetry is 

 always parallel to the surface of the disk. These, 

 together with tourmaline, diamond, gold, and 

 platinum, were found in the conglomerates near the 

 Kaieteur Falls on the Potaro River. Platinum has 

 not hitherto been recorded from British Guiana. — 

 H. E. Buckley : Some anomalous optical properties \ 

 of freshly-prepared mixed crystals of the Seignette j 

 salts. In the orthorhombic and isomorphous Sei- 

 gnette salts the sodium -p>otassium tartrate has the 

 optic axial plane parallel to the brachy - pinacoid, 

 whilst in the sodium-ammonium salt it is parallel to 

 the macropinacoid. Mixed crystals of the two salts 

 show, as would be expected, the optic axes for 

 different colours in two planes at right angles (as in 

 brookite), but only after the crystals have been 

 prepared for some time. Freshly-prepared mixed 

 crystals exhibit crossed dispersion of the monoclini 

 type (as in borax). A maximum angle of 75° between 

 the axial planes for red and \'iolet light is given by 

 crystals containing 45 p>er cent, sodium-potassium 

 tartrate. On standing, the axial planes slowly 

 migrate to the planes of symmetry*, and equilibrium 

 is established in from two to thirteen weeks, this 



