February 2, 1905] 



NATURE 



333 



wealth of the country to the same extent as they used to 

 do, or else that many boys often proceed to get up the subject 

 from the point of view of satisfying a miserable minimum. 

 What was asked for is a relaxation in favour of education 

 in general and not in favour of any special class of people. 

 The elimination of literary training in the country is not 

 being sought. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, November 24, 1904. — " Pieliminary Com- 

 munication on Galvanic Cells produced by the Action of 

 Light." By Dr. M. Wilderman. (From the Davy- 

 Faraday Laboratory of the Royal Institution.) 



The author finds that there is, under the action of light, 

 a region of galvanic cells as wide and as varied as in 

 the case of ordinary galvanic cells. He finds constant and 

 inconstant cells, reversible and irreversible cells. The 

 chemical reactions and chemical equilibrium in the galvanic 

 combinations are now perfectly clear ; they prove, however, 

 to be all sui generis, all the phenomena being intermixed 

 and characterised by phenomena of induction and deduc- 

 tion, peculiar to light cells only. The author also 

 succeeded in placing this region of phenomena on a physico- 

 mathematical basis, testing and proving the fundamental 

 equations experimentally in all details. The principal 

 results obtained are : — 



(i) The total E.M.F. created by light consists of an 

 E.M.F. produced by light at a constant temperature, 

 owing to the increase of the chemical potential and of 

 the solution pressure of the exposed plate, and of a thermo- 

 E.M.F. caused by one of the plates in contact with the 

 liquid being heated by light. Both E.M.F.'s are found to 

 be directly proportional to the intensity of light ; both 

 give currents in the same direction, thus proving that 

 light acts on the chemical potential as well as on the 

 solution pressure of the electrode in the same way as 

 does heat. 



(2) The peculiar course of the induction and deduction 

 periods enables one to distinguish constant and inconstant 

 cells showing polarisation from one another. A consider- 

 ation of the chemical composition and of the reactions 

 going on in the systems under the action of the current 

 leads to the same results. 



(3) The induction period follows a law 



giving at the same time also the fundamental law of 

 photography relating to the connection between the amount 

 of silver salts decomposed and the time of exposure. The 

 deduction period follows a similar law 



(4) The fundamental equation for the E.M.F. of con- 

 stant cells " reversible in respect of cation " {e.g. Ag plate 

 In light, AgNOj solution in light, AgNO, solution in the 

 dark, Ag plate in the dark) is 



2E = o-86oT (log,. I',/P,i-2z>/u + z> log,. /,//>,,) lo-" volt, 

 and for constant cells " reversible in respect of the 

 anion " (e.g. Ag-BrAg plate in light, KBr solution in 

 light, KBr solution in the dark, Ag-BrAg plate in the 

 dark) is 



2E = o-86oT(-log, Pi/Pa + 2u/ii + T log„/(//rf)io-' vol', 

 where P,, P^ are the solution pressures of the electrodes 

 in light and in dark, p,, />,, are the osmotic pressures of 

 the cation or anion in the solution in light and in dark, 

 and T is the absolute temperature. 



The theory of thermogalvanic cells is also given in the 

 paper. 



December 8, 1904. — " The RSle. of Diffusion during 

 Catalysis by Colloidal Metals and Similar Substances." 

 By Dr. Henry J. S. Sand. Communicated by Prof. J. H. 

 Poynting, F.R.S. 



This paper contains a criticism of the opinion expressed 

 by Nernst {Zeitschrift Phys. Chem., xlvii., 55) that the 

 catalytic decomposition of hydrogen peroxide due to 



NO. l8^0, \0L 71] 



colloidal metals probably takes place practically instan- 

 taneously on the surface of the catalyser, so that the 

 concentration of the hydrogen peroxide there is permanently 

 maintained at zero, and the velocity of the reaction actually 

 measured is that with which diffusion and convection 

 renew the solute in contact with the catalytic particles. 



As a result, it was shown that Nernst's hypothesis 

 would lead us to expect the reaction to proceed as one 

 of the first order, a conclusion which agrees with the 

 e.xperimental results found by Bredig and his pupils. The 

 actual values of the experimental velocity-constants are, 

 however, far too small to allow us to reconcile them with 

 Nernst's suggestion, and the latter must therefore be 

 rejected. 



In order to arrive at this result, minimum theoretical 

 values for the rate of the reaction were calculated on 

 Nernst's hypothesis. For this purpose the particles were 

 assumed to be spheres with a diameter of 0-5,14, a value 

 which, according to Bredig, is greater than any which 

 was met with in his solutions. The particles were sup- 

 posed to be in a state of continual movement, performing 

 the so-called Brownian motions, but in travelling through 

 the solution were assumed to take with them a film of 

 adhering liquid. In order to obtain a minimum value for 

 the reaction velocity the total volume of the films was 

 supposed to be equal to that of the whole liquid. The 

 diffusion-coefficient of hydrogen peroxide at 25° was taken 

 as 10-^ cm. -/sec, a value which is smaller than that of 

 most substances with heavier molecules. 



The great part played by convection due to the Brownian 

 motions of the particles and stirring by gases, &c., was 

 demonstrated, it being pointed out that the experimental 

 results regarding the dependence of the velocity-constants 

 on the concentration of the catalyser can only be reconciled 

 with the idea of a heterogeneous reaction if convection 

 plays an important part. 



Lastly, it was shown that the experimental facts all 

 agree with the assumption that the actual velocity of the 

 reaction on the surfaces of the particles always has a 

 finite value which is proportional to the concentration of 

 the solute in immediate contact with them. 



In conclusion, Nernst's views regarding reaction- 

 velocities in heterogeneous systems were criticised from 

 a thermodynamical point of view, and it was shown that 

 whereas they may possibly be correct for the majority of 

 physical processes, great caution should be exercised in 

 applying them to processes of a chemical nature. 



January 19. — " The Dual Force of the Dividing Cell. 



Part i. — The Achromatic Spindle-Figure, elucidated by 



Magnetic Chains of Force." By Prof. Marcus Hartog. 



Communicated by Sir William T. Thiselton-Dyer, 



K.C.M.G., CLE., F.R.S. 



The essential points of this research are described as : — 

 (i) The introduction of a convenient apparatus for the 



study of the axial section of fields produced by isolated 



poles of a dual force. 



(2) rhe formation of chains of force in a viscid material, 

 the recognition of their character as a distinct type of 

 material configuration, and the study of their properties. 



(3) The application of the conception of relative per- 

 meability, and of the recognition of chains of force to 

 the problem of the cell-figure. 



Zoological Society, January 17. -Mr. G. A. Boulenger, 

 F.R.S., vice-president, in the chair. — (i) Some notes on 

 the cranial osteology of the mastigure (Uromastix) ; (2) 

 a contribution to the anatomy of Chlamydosaurus and 

 some other Agamid;i; ; and (3) a note on the brain of 

 Cynopithecus iiigcr : F. E. Beddard, F.R.S. — (i) A 

 collection of sipunculids made at Singapore and Malacca ; 



(2) a collection of gephyrean worms from Zanzibar ; and 



(3) the sipunculids and echiurids collected during the 

 " Skeat Expedition " to the Malay Peninsula : W. F. 

 Lanchestei'. Four new species were described in the 

 second paper and nine in the last. — On the oral and 

 pharyngeal denticles of elasmobranchs : A. D. Imms. 

 The author had found that these denticles were present 

 in varied abundance over the mucous membrane lining 

 both the oral and pharyngeal cavities in many of these 

 fishes. Out of the specimens of the nineteen species 



