t)I2 



NATURE 



[January 30, 1913 



Spring Gardens, on the evolution of epidemics. In 

 June Dr. p". \V. Mott, F.R.S., will give a course at the 

 Roval Society of Arts, under the title of " Nature and 

 .Nurture in Mental Development." Among the lec- 

 tures in contemplation for the provincial cities are 

 those on the public inilk supply — some criticisms and 

 suggestions from ^he public health point of view — by 

 Prof. Henry R. Kenwood, at Manchester, and on 

 water supply, with exhaustive consideration of 

 sources, collecting works, conveyance, and distribu- 

 tion, by Mr. E. P. Hill, at BiVmingham. All the 

 lectures will be free and open to the public, but will 

 be of a character to attract post-graduate and advanced 

 students of engineering, medicine, and other cognate 

 sciences. The secretary to the trust, to whom all 

 communications should be addressed, is Mrs. Aubrev 

 Richardson, 8 Dartmouth Street, Westminster. 



SOCIETIES AND ACADEMIES. 

 London. 

 Royal Society, January i6.— Sir Archibald Geikie, 

 K.C.B., president, in the chair. — Lord Rayleigh : The 

 effect of junctions on the propagation of electric waves 

 along conductors. — W. B. Hardy : The influence of 

 chemical constitution upon interfacial tension and 

 upon the formation of composite surfaces. — Hon. R.J. 

 Strutt : Duration of luminositv of electric discharge 

 in gases and vapours. — Rev. P. J. Kirkby and J. E. 

 Marsh : Some electrical and chemical effects of the 

 explosion of azoimide. The experiments consisted in 

 exploding azoimide gas (HN,) at low pressures be- 

 tween two insulated coaxial cylinders, of gilded brass, 

 connected to the terminals of a battery of about 105 

 volts. The quantity of electricity that reached one of 

 the cylinders was measured by a ballistic galvano- 

 meter and compared with the quantity of gas ex- 

 ploded. The results show that, in every case, the 

 number of molecules of gas exploded was more than 

 100,000 times the number of pairs of gaseous ions 

 observed. This disproportion indicates that the atoms 

 of the gas when separated by the explosion do not 

 carry electric charges. The gaseous ions are probably 

 produced by favourable collisions of free atoms in the 

 process of forming the products of the explosion. — Dr. 

 G. J. Burch : Negative after-images with pure spectra! 

 colours. The results obtained by Mr. A. W. Porter 

 and E)r. Edridge-Green in their experiments on nega- 

 tive after-images and successive contrast with pure 

 spectral colours (Proceedings B, vol. Ixxxv., p. 434) 

 can be explained in accordance with the theory of 

 Thomas Young if the "stray light" referred to by 

 the authors is taken into account. Thus fatigue by 

 red light renders the blue and violet of a spectrum 

 projected on a screen in an imperfectly darkened 

 room darker and bluer along the line of the after- 

 image, because it removes the red constituent of the 

 "stray light" with which they are contaminated. 

 The results of fatigue wHth other spectral colours may 

 be similarly explained. — H. Harfridge : Factors affect- 

 ing the measurement of absorption bands. — Dr. G. 

 Barlow : A new method of measuring the torque pro- 

 duced by a beam of light in oblique refraction through 

 a glass plate. .According to theory, the torque pro- 

 duced on a tjlass plate by the nearly nornnl passage 

 of a beam of light is directly proportional to the angle 

 of incidence and always tends to turn the plate further 

 from the normal position. The period of small tor- 

 sional oscillations of a plate suspended by a quartz 

 fibre should therefore be increased when the plate is 

 traversed by the light. An experiment is described in 

 which this change in period, actually an increase of 

 about i per cent., was measured. The observed 

 change agreed within 3 per cent, with that calculated 



NO 2257. VOL. go] 



from theory. — Dr. F. Horton : The positive ionisation 

 produced bv platinum and by certain salts when 

 heated. The emission of positive electricity from 

 platinum and from several samples of aluminium 

 phosphate and of sodium phosphate has been inves- 

 tigated at different temperatures, observations being 

 made of the variation of the emission with time and 

 with the pressure of the surrounding gas. — Clive 

 Cuthbertson and Maude Cuthbertson : The refraction 

 and dispersion of the halogens, halogen acids, ozone, 

 steam, o.xides of nitrogen and ammonia, and the 

 causes of the failure of the additive law. The refrac- 

 tion and dispersion of the elements and compounds 

 named in the title have been determined betweer 

 ^ = 6708 and X = 48oo. — R. Donald : Liquid measure- 

 ment by drops. To apply measurement by drops to 

 various serological and bacteriological estimations of 

 liquids and liquid suspensions, the author has worked 

 out a system of using practically uniform easily-made 

 pipettes of anv size under any required constant pres- 

 sure. Tlir pipettes of suitably drawn-out glas.; tubing 

 are simplv gauged in, e.g. the Morse drill and wire 

 gauge. '1 he constant pressure is obtained by a 

 column of mercury flowing as a piston to and fro 

 in a suitab: ' glass tube held at any required angle 

 in a stand, or, for less exact work, in the hand. — Prof. 

 W. H. Young : The new theory of integration. T}'.i' 

 present communication is a sketch of a mode whereby 

 the modern theory of generalised, or Lebesgue, in- 

 tegration may be developed without the aid of the 

 theorv of sets of points. 



Mineralogical Society, January 21. — Dr. A. E. H. 

 Tutton, F.R.S., president, in the chair.— T. V. Barker 

 and J. E. Marsh : Optical activity and enantio- 

 morphism of molecular and crystal structure. The 

 general nature of enantiomorphous structures accom- 

 panying optical activity in the liquid and crystalline 

 conditions was discussed, and it was pointed out that, 

 since the optical activity observed in crystals of six 

 substances, including epsomite and sodium chlorate, 

 <-annot be referred to the crystal structure, it must 

 be due to an enantiomorphous configuration of the 

 atoms within the molecule. Suitable enantiomorphous 

 configurations have been deduced on cheinical 

 grounds, the constitution of the compounds being 

 based on a modification of Werner's theory of co- 

 ordination. The symmetry of the new spatial formulae 

 is in many cases identical with the symmetry of the 

 crystal, and, in particular, sodium nitrate can best be 

 regarded as a racemate due to a mutual interpenetra- 

 tion of optical antipodes having spatial configurations 

 similar to those suggested for the active forms of 

 sodium chlorate, the symmetry of the double molecule 

 being identical with that of a rhombohedron. The 

 same type of molecular structure presumably exists in 

 calcite and the rhombohedral form of sodium chlorate 

 which crystallises at high temperatures. It is con- 

 cluded that many cases of dimorphism are of an 

 analogous character, and, more generally, that poly- 

 morphous change is preceded bv a rearrangement of 

 the atoms within the molecule.— H. Collingridge : Note 

 on the determination of the optic axial angle of 

 crystals in thin-section. In the case where one optic 

 axis is visible in the field of view the position of the 

 second axis may be determined more conveniently than 

 in the Becko and Wright methods from the optic 

 axial plane and the extinction direction through the 

 centre of the field.— Dr. G. F. H. Smith : Graphical 

 determinations of angles and indices in zones. Two 

 methods were described, which, unlike the moriogram, 

 are not restricted to right-angled zones. In one a 

 double tangent scale is placed on a pencil of lines 

 spaced as in n gnomonic projection on a zonal plane 

 in such a wav that the 01 and 11 lines cross the scale 



