702 



NATURE 



[July 28, 192 1 



Societies and Academies. 



London. 

 Faraday Society, June 22.— Prof. A. W. Porter, 

 president, in the chair.— C. J. Smlthellg (for the Re- 

 search Staff of the General Electric Co.) : High- 

 temperature phenomena of tungsten filaments. 

 Part i. Two types of tungsten wire are in general 

 use for lamp filaments. One is composed of pure 

 tungsten, and the other of tungsten containing up to 

 I per cent, of a refractory oxide such as thoria. The 

 crystal growth during burning has been investigated 

 for both types. It is shown that the deformation of 

 the filament which occurs during life is a function of 

 the crystal growth. Crystal growth, which is sup- 

 pressed in thoriated filaments, occurs when the thoria 

 is reduced. Thoria and other refractory oxides can 

 be reduced by phosphorus vapour at a high tempera- 

 ture. Part ii. deals with the chemical reactions which 

 occur in gas-filled tungsten filament lamps when 

 traces of the common gases are present in the filling 

 gas.— E. Hatschek : A simple apparatus for deter- 

 mining the coagulation velocity of gold sols. The 

 percentage of blue formed in coagulation of red gold 

 sol is taken as a measure of the degree of coagulation. 

 The percentage is determined by comparing the 

 original red sol with a double wedge, one half con- 

 sisting of the original sol, and the other of the com- 

 pletely coagulated blue sol. It is necessary that the 

 latter should be coagulated by the same electrolyte 

 as that used in the sol under examination, as the 

 blues obtained with different electrolytes are not 

 exactly alike. A number of determinations have been 

 compared with V. Smoluchowski's formula for the 

 coagulation velocity, and show good agreement for 

 complete and fairly rapid coagulation. — Prof. A. W. 

 Porter : The variation of surface tension and surface 

 energy with temperature. Any satisfactory formula 

 must correspond with the vanishing of both the sur- 

 face tension o- and the surface energy u at the critical 



point. The connection is u — cr-'Yf 



hence 



ao- 



'f)T ' ar 



must also vanish at the critical point. These condi- 

 tions are all satisfied by the formula put forward by 

 van der Waals, and afterwards by Allan Ferguson, 

 viz. 



o- = constant (T^-T)n, 



where n is a constant between 1-2 and 1-3. Whittaker 

 has shown that u is proportional to T x internal latent 

 heat. The author shows that if the reduced tempera- 

 ture be taken as the factor (instead of T), the numeric 

 values show that for many substances u and the 

 internal latent heat of evaporation tend to equality (on 

 the C.G.S. system) as the temperature is approached. 

 He also directed attention to the connection between 

 van der Waals 's equation for a- and Thiessen's equa- 

 tion for the latent heat, a- = constant (T^-T)*", where m 

 is about 0-3.— S. M. Neale : The influence of solvent 

 upon ionisation and the accompanying heat effect. A 

 determination by electrical conductivity methods of 

 the ionisation of picric and /)aranitrobenzoic acids in 

 mixtures of acetone and water. From the values ob- 

 tained at 25° and 35° C. the heats of ionisation are 

 calculated. In the case of picric acid the heat of 

 ionisation varies largely with the nature of the sol- 

 vent, passing through a minimum at about 70 per 

 cent, acetone.' In the case of /)aranitrobenzoic acid the 

 heat of ionisation is sensibly zero both In water and 

 in 44 per cent, acetone, although in the latter solvent 

 the ionisation constant has fallen to i/2oth of its 

 value in pure water as solvent. — A. McKeown : The 

 potential of the iodine electrode and the activity of 

 the iodide ion at 25° C. The potential of the saturated 

 NO. 2700, VOL. 107] 



lodme electrode m combination with the normal 

 calomel electrode has been measured for various values 

 ot the concentration of the iodide ion. The results 

 have been compared with those of other investigators 

 makmg use of the concept of activity coefficient • the 

 activities of the iodide and of the tri-iodide ion in the 

 various solutions have been estimated and compared 

 with the values of the concentration of these ions 

 It IS found that the activities of both ions increase 

 less rapidly than their concentrations. From the 

 results the normal potential of the iodine electrode is 

 calculated to be +02454 volt, the normal calomel 

 being taken as zero. 



Paris. 

 Academy of Sciences, July 4.— M. Georges Lemoine 

 in the chair.— The president announced the death 

 through a motor-car accident of Jules Carpentier, free 

 member.— G. Lemoine : The mutual reaction of oxalic 

 acid and iodic acid. The influence of different cata- 

 lysts. As catalysts, platinum sponge, platinum black, 

 wood charcoal, and sugar carbon were used. In 

 general, for the same reaction velocity a higher tem- 

 perature was necessary in the absence of a catalyst. 

 Increasing the weight of catalyst increased the re- 

 action velocity, but this was proportional neither to 

 the weight nor to the surface. The activity of the 

 platinum black was very great in proportion to the 

 other substances. — A. de Gramont : Spectra of quan- 

 titative sensibility of silicon in fused salts and in 

 steels. Working with fused salts, two characteristic 

 lines of silicon persist down to a content of 0005 per 

 cent, of silicon. With steel, the sensibility is less on 

 account of the brightness and number of the iron 

 lines.— P. Sabatier and B. Kubota : The action of heat 

 on allyl alcohol in presence of various catalysts. 

 There are two main reactions, dehydrogenation and 

 dehydration ; copper and manganous oxide especially 

 efl"ect the first of these, and tungstic acid, thoria, and 

 alumina the second. With zirconia and uranic oxide 

 both reactions occur together. Owing to secondary 

 changes the final product is very complex, and con- 

 tains water, acrolein, propyl alclehyde, higher alde- 

 hydes formed by condensation, and hydrocarbons 

 (mesitylene). The gases include propylene, hydrogen, 

 carbon monoxide, and dioxide, but neither acetylene, 

 allene, nor allylene could be detected. — B. Gambler : 

 Imaginary surfaces applicable to a surface of revolu- 

 tion ; real corresponding cyclic systems. — D. Ria- 

 bouchinslii : The cyclic movement of a liquid round 

 a solid which moves parallel to a rectilinear wall. — J. 

 Mascart : Observation of the occupation of Venus of 

 July I, • I921, made at the Observatory of Lyons. 

 Observations were made under good atmospheric 

 conditions by six observers with different types of 

 instrument." — E. Belot : The law of rotation of the 

 sun explained by evolution and flattening of the proto- 

 sun.- — M. Brllloiiin : Bohr's atom. The circumnuclear 

 Lagrange function. — A. Lafay : The figures of M. de 

 Heen and the electric discharge. — M. Solomon : A 

 radiological ionometric arrangement. A description 

 of an apparatus for the measurement of ionisation 

 in medical radiology. It is standardised by a known 

 quantity of radium. — A. Dauvillier : The principle of 

 combination and the absorption lines In the X-ray 

 spectra. ^ — A. Marcelin : Surface tension of the mono- 

 molecular layers. — A. de G. Rocasolano : Variations 

 of catalytic power In the electroplatinosols. — G. 

 Tanret : An ammonium molybdo-quinate. Quinic 

 acid Is known to show a marked increase In rotatory 

 power when mixed with solutions of molybdates. This is 

 due to the formation of a definite complex compound, 

 ammonium molybdo-quinate, the Isolation and analysis 

 of which are described.— J. Cvijic : The correspondence 



