192 



NA TUK/: 



\_Dec. 20, 188- 



of M. Kertrand, by M. Georges Ossian Bonnet. — Forn^ulas giving 

 the eleclric resiftarce of the circuit employed in the Edison 

 system of electrical lighting, by M. G. Gueroult. — Observations 

 relative to a method of studying earlh currents, in connection with 

 a communication recently made by M. Ulavier, by M. V. Larroque. 

 —Researches on the solidification of juperfufed sulphur (second 

 part), by M. P. Gernez. — Determinalion of the equivalent of 

 aluminium by means of its sulphate, by M. H. Bauhigny.— On 

 the formation cf acetylene at the expense of the iodoform, by 

 M. r. Carereuve.— New researches on the susceptibility of the 

 eye to differences of luminous intensity, by M, Aug. Charpentier. 

 — Cholera, small-pox, typhoid fever, and charbon amongst the 

 coppersmiths of Villedieu, by M. Bochefonlaine. Although the 

 whole atmosphere of the place is, so to say, saturated with copper, 

 nine of the inhabitants of Villedieu, all engaged in the copper 

 industr)', fell victin s to cholera in 1849. Considering the differ- 

 ence of population, this would represent a mortality of 5700 in 

 Paris. Nearly half of the population was attacked by. small-pox 

 in 1870, and a fatal case of charbon occurred in 1865. — On the 

 existence and distribuiion of eleioine in the bucco oe-ophagian 

 raucous menibrane of mammals, by ^^. L. Ranvier. — On the 

 genus Vcjquia, a fossil yew f..und in the Aachen formations of 

 Tournai, by M. C. Eg. Bertrand. — On a luminous phenomenon 

 ob.=erved after sunset at Amiens on 'everal evenings about the 

 end of November and begiining of December last, by M. 

 Decharme. The author fetls inclined to attribute the-e effects 

 to the aurora borealis. Details of similar manifestations observed 

 in other places were quoted from a rec nt number of Nature. 



Berlin 

 Physical Society, November 30.— Dr. Kayser placed be- 

 fore the meeting a concave grating sent by Prof. Rowland to the 

 Physical Institute, explained the principle of this apparatus, and 

 exhibited a photograph of the normal spectrum produced by 

 help of the grating, as also a negative prepared by Prof. Row- 

 land, on which Dr. Kayser was able with the naked eye to count 

 between the two H lines over seventy fine lines, among which 

 some appeared to form groups, so that by means of a microscope 

 many n ore lines ^till would be distinguishable. — Prof, von 

 Helmhfltz next gave a minute report of the continuation of the 

 experiments he had instituted with a view to explaining galvanic 

 polarisation according to thermodynamic principles. Suppose 

 that an electric current passed through a liquid completely free 

 of gas, then would the gases generated by decomposition of the 

 electrolyte be first absorbed by the liquid, and only after the 

 latter was saturated to a degree corresponding with the pressure 

 of gas resting on it would the development of gas begin. The 

 previous solution of gas in the liquid was the expression of an 

 attraction or of a molecular energy between the water and the 

 gas, which acted in the same direction as did the electromotive 

 energy which decomposed the electrolyte at the electrode. The 

 absorption of the gas, therefore, agreeably with the teaching of 

 the matbeuiatical theory, increased the electromotive energy, 

 and all the more so the less gas the liquid contained. This 

 accorded with the experience derived from experiments that the 

 convective current w as so much the stronger by how much the 

 less gas the f^uid had absorbed. If the liquid already contained 

 gas in solution, a part of it would escape at the surface by a kind 

 of dissociation, and form above the liquid an atmosphere the 

 pressure of which corresponded with that of the momentary 

 saturation of the liquid. This dissociation of the solution repre- 

 sented a work which could reciprocally be applied to the con- 

 version ot gas to a liquid state; that is to say, supposing the 

 conditions were -uch that the temperature of the system was main- 

 tained througbout unaltered, the whole process was a reversible one. 

 With thi- consideration let one .start from any normal condition 

 whatsoever, from atmospheric pressure for example, then it w as 

 the teaching of the theory that the v>ork was all the greater the 

 less was the quanti'y of gas in solution, and in the case of very 

 small gas volumes the work would be endless, that is to say, in 

 every fluid were ili-solved minute quantities of gas which could 

 no longer be discharged. If the electrolytic fluid contained 

 ■ oxygen in solution, as in fact was regularly the case, the 

 oxygen would be drawn by convection tow-ards the oxygenous 

 electrode, and there augmented by the oxygen which had been i 

 electrolytically separated, and after loss of its electricity be- 

 come neutral. The gas would now begin to diffuse itself 

 towards Ihi: other, the hydrogenous electrode, and this difllusion 

 would pri iduce the polarisation current which, just as much as 

 the diffusion stream, was opposed to the electrolytic current and 



convection. The quantity of oxygen in the fluid and its diffii- 

 sion might be illustrated by a curve which ascended from the 

 hydrogenous electrode as its zero point rectilinearly to the oxy- 

 genous electrode, and so long as the electromotive force 

 remained the same at the electrodes a state of equilibrium was 

 maintained between electromotive force, convection, polarisation 

 current, and difl'usion ; a state of equilibrium w hich was disturbed 

 when the current w.is interrujited for however short a time. The 

 theory of these processes taught, what experience confirmed, 

 that a much greater electromotive force was required after the 

 interruption to re-establish electrolysis than was before needed 

 to continue the process. If the fluid were saturated with gas to 

 a degree corresponding with the pressure of gas resting on it, 

 the gases generated by electrolysis escaped. .Seeing, however, 

 that the degree of saturation was dependent on the pressure of 

 gas, therefore, with the increase of gas pressure, the electro- 

 motive force which caused the development of gas would like- 

 wise have to be increased. It was now sought to ascertain the 

 least rlectromotive force that was sufficient under a definite 

 pressure to cause a development of gas, and the experiments 

 made with this object in view showed that the developtnent of 

 the fir-t bubbles had to overcome a cinsidera'ile resistance, and 

 therefore demanded intenser currents than were needed for later 

 gas bubbles. When, by a definite current through an extended 

 metallic wire, gas was developed in an electrolyte, by lessen- 

 ing the electromotive fjrce it w.as possible to produce only 

 single gas bubbles at one point of the wire. The same amount 

 of electromotive force which was sufficient to produce this 

 effect was not, however, equal to the generation of bubbles from 

 the out-et. To effect this latter result, a much stronger current 

 would have to be employed. All these processes and relations 

 here briefly indicated were mathematically calculated, and the 

 results of the experimentsinvariably coincided with the teachings 

 of the theory. 



CONTENTS Page 



Merrifield's " Treatise on Navigation" 169 



Our Book Shelf:— 



Curtis's "Farm Insects" 170 



Letters to the Editor : — 



Evolution of the Cetacea. — Prof. W. H. Flower. 



F.R.S 170 



The Java Eruption. — ^J. J. Harris Teall .... 170 

 Diffusion of .Scientific Memoirs. —Prof. Silvanus P. 



Thompson 171 



Deer and their Horns.— Sir J. Fayrer, F.R.S. 



(With Illustralion) 171 



Sprengel on the Fertilisation of Flowers. — Prof. W. 



Whitman Bailey 171 



.Salt Rain and Dew. — F. Gillman f'172 



Lunar Rainbow. — C. H. Romanes ; M. F. Dunlop 172 

 Professor Ntlsson. By Dr. J. Gwyn Jeffreys, 



F.R.S 172 



Semitico-Oceanic Linguistic Affinities. By Prof. 



A. H. Keane 172 



American Wheat. By Prof. John Wrightson . . 173 

 The Remarkable Sunsets. By the Editor ; Drs. 

 M. W. Beyerinck and J. van Dam; Rev. W. 

 Clement Ley ; E. Douglas Archibald ; Dr. James 

 Macaulay ; Dr. Budde ; Arthur Severn ; J. LI. 

 Bozward ; B. J. Hopkins ; F. Gillman ; Prof. 



J. P. O'Reilly 174 



The Krakatoa Air- Wave. By General Strachey, 



F.R.S 181 



Notes 183 



Our Astronomical Column : — 



The Mass of Saturn 185 



Close Double-Stars 185 



Pons' Comet 185 



Tempers Comet, 1S67 II 185 



De Morgan's Five-Figure Logarithms 185 



Probable Nature of the Internal Symmetry of 



Crystals. By William Barlow ( /!V//i /)/i;^;-a/«.f) . 186 

 The Helvetic Society of Natural Sciences . . . . l88 

 Notes from the Otago University Museum, I'V. By 

 Prof. T. Jeffery Parker (/r/rt £>;«!,'«/«) .... 189 



Scientific Serials 190 



Societies and Academies 190 



