Nov. 29, 1888] 



NATURE 



119 



^tiuly of the electrolysis of magnesium chloride solution, by 

 ' -srs. Cross and Bevan. The authors find that the white 

 -lance separated at the cathode under the condition that the 

 .tion is not kept in circulation is a chloroxygen compound of 

 _;nesium, probably a magnesium hypochlorite. Similar com- 

 iinds are formed on electrolyzing solutions of magnesium 

 niide and iodide. — The heat of dissolution of various sub- 

 i.ces in different liquids, by Mr. S. U. Pickering. The heats 

 dissolution of the nitrates and chlorides of calcium and 

 iiihium in water and in alcohol, and of bromine and iodine 

 in various liquids, have been determined ; and the results are held 

 to support the author's view that the affinity of the radicles com- 

 posing a salt molecule is rot entirely saturated by their combina- 

 tion, and that the "residual affinity" of one of the>e radicles 

 becomes entirely saturated by the solvent ; the heat of combina- 

 tion of the atoms and the heat of dissolution of the molecule 

 which they form being thus parts of the same chemical operation. 

 — The criteria of plane and axial symmetry, by Prof. Armstrong, 

 F. R.S. Wislicenus, in his now widely-known paper on the 

 space arrangement of the atoms in carbon compounds, has 



a.C.b 

 termed compounds of the form ll axially symmetric, and 

 b.C.a. 

 a.C.b. 

 those of the form || plane symmetric. In allocating these 



a.C.b. 

 formula, he has argued, in a case such as is affiarded by the two 

 tolane dichlorides, for example, that the compound of higher 

 melting-point (143°) is necessarily the plane symmetric modifica- 

 tion, as it is produced on chlorinating tolane - + Cl^ = 



g;6H5.c 



CfiHs.CCl 



, and from the three possible configurations of tolane 

 QHs.CCl 



tetrachloride has arrived at the conclusion that on reduction it 

 should yield the axially symmetric tolane dichloride in the larger 

 quantity. Blank's experiments {Annalen, ccxlviii. i) show that 

 the two isomeric dichlorides are produced nearly in the pro- 

 portion of two parts of that of lower melting-point (63°) to one 

 of that of higher melting-point, and the axially symmetric 

 structure is therefore, it would seem, as a matter of course, 

 assigned by him to the dichloride melting at 63°. The 

 author regards these views as being based on pure assump- 

 tions, and shows that all the facts at present known tend to 

 prove that symmetric compounds — such as the para- or symmetric 

 di-derivatives, or the symmetric tri- arid tetra-derivatives of 

 benzene, or the axially symmetric ao or j8/3 modifications in the 

 case of isomeric di-derivatives of naphthalene — have always the 

 highest melting-point. The tolane dichloride of higher melting- 

 point is therefore probably the axially symmetric modification. 

 The majority of "alloisomerides " are compounds containing 

 unsaturated carbon usually in association with one of the 

 halogens or oxygen, and the author points out that it does not 

 appear that this circumstance has yet been taken into account, 

 or that the extent to which the peculiarities manifested by the 

 negative elements are concerned in and may condition the 

 isomerism has been in the least considered. The symbolic 

 system introduced by Van 't Hoff, and adopted by Wislicenus, 

 tends, moreover, to withdraw attention from the consideration 

 of the possible effect of the peculiarities referred to, inasmuch 

 as a "double bond" is represented as the precise equivalent of 

 two, and a treble bond as that of three single bonds ; which all 

 observations show is a misrepresentation of the facts. — Deriva- 

 tives of methylindole, by Dr. H. G. Colman. — Acetamide and 

 phenanthraquinone, by Dr. A. T. Mason. — The action of 

 ethylenediamine on succinic acid, by the same. 



Paris, 

 Academy of Sciences, November 19. — M. Janssen in the 

 chair.— On the " Collection of the old Greek Alchemists," by M. 

 Berthelot. The parts now presented to the Academy complete 

 the publication of the Greek text and French translation of this 

 great work. Part v. contains technical treatises of special 

 interest on the goldsmith's art, the tempering and colouring of 

 bronze and iron, bronze casting, iron-gilding, the preparation of 

 gold-leaf, the colouring of artificial gems, the treatment of ptarls, 

 the preparation of lye from ashes, beer, soap, &C. Most of these 

 treatises appear to have formed part of a great work on practical 

 chemistry composed in the eighth and ninth centuries, and several 

 are written in the Byzantine dialect. But SDme are of great 



antiquity, amongst others one dealing with the phosphorescence 

 of precious stones. — On the satellite of Neptune, by M. F. 

 Tisserand. — On the latitude of the Gambey mural circle at the 

 Paris Observatory, by M. H. Faye. A method is proposed by 

 which the exact latitude of the instrument itself may be directly 

 determined, and the results controlled which have been obtained 

 with other processes by M. Perigaud in the present year, and by 

 others at earlier dates. M. Perigaud determines the latitude of 

 the Observatory as 48' 51' io""9. — Note on the stability of the 

 French seaboard, by M. Bouquet de la Grye. The results of 

 the comparative observations taken for some years past at the 

 ports of Brest, Cherbourg, and Havre, tend mainly to confirm 

 the general researches of Colonel Goulier. From the compara- 

 tive tables it appears that the mean level diminishes in the 

 direction from Brest to Havre ; at Havre the annual subsidence 

 seems to be about 2 mm., at Cherbourg I mm., at Brest nearly 

 absolute stability. — A study of submarine navigation, by M. A. 

 Ledieu. A survey is given of the futile efforts made in this 

 direction previous to the invention of Whitehead's regulating 

 pendulum in 1872 ; which, combined with M. Joseph Farcot's 

 servo-motor, gave the true solution of the problem. From that 

 time dates all real progress in submarine navigation. — On various 

 methods of treating rabies, by M. Odo Bujwid. Since his visit 

 to M. Pasteur's establishment in 1886, M. Bujwid has been 

 treating persons bitten by dogs, either mad or suspected of 

 being mad, in his laboratory at Warsaw. At first he followed 

 the simple processes of inoculation of ^f. Pasteur, and of M. 

 Frisch, of Vienna, with some failures in both cases. But during 

 the last sixteen months he has adhered exclusively to the inten- 

 sive or severe treatment, which has been applied to 370 patients 

 without a single fatality. — Observations of Palisa's new planet 

 (281), and of Barnard's comet (October 30, 1888), made at the 

 Observatory of Algiers with the 0*50 m. telescope, by MM. 

 Rambaud, Sy, and Renaux. The observations of the planet are 

 for the period from November 3 to November 8 ; those of the 

 comet from the 5th to the 8th of the same month.— On the sub- 

 sidence of the land in France, by Colonel Goulier. In reply to 

 General Alexis de Tillo's remarks on his previous note, the 

 author points out that his conclusions on this subject are not put 

 forward as final, but only as a probable hypothesis to be accepted 

 until proved untenable. — On mountain-ranges and their relations 

 to the laws of deformation of the terrestrial spheroid, by M. A. de 

 Grossouvre. On purely theoretical considerations the author 

 arrives at the conclusion that the zones of foldings are progres- 

 sively receding southwards. This conclusion is entirely in 

 accordance with the observed facts connected with the disloca- 

 tion of the earth's crust, and the regularity of the phenomenon is 

 regarded as a confirmation of the theory of the primitive fluidity 

 of the globe. — On equalities of two degrees, by M. Michel 

 Frolov. These researches have reference to the properties of 

 groups of « numbers, whose first and second powers give re- 

 spectively equal sums, properties which have not yet been 

 studied by any other arithmetician. — Maximum spectrum of 

 Mira Ceti, by Mr. J. Norman Lockyer. — On the mutual 

 relations of meteorites and >hooting-stars, by M. Stanislas 

 Meunier. — Note on the tensions of various vapours, by M. Ch. 

 Antoine. — On the decomix)silion of the haloid salts of silver 

 under the influence of light, by M. F. Griveaux. — Hydro- 

 chlorates of benzidine : their dissociation by water, by M. P. 

 Petit. 



Berlin. 

 Physical Society, November 2. — Prof, von Helmholtz, Presi- 

 dent, in the chair. — Dr. Brodhun gave an account of experiments 

 which he had made, in conjunction with Dr. Konig, for the pmpose 

 of testing the fundamental law of psychophysics in connection with 

 the sense of sight. These have already been described by Dr. 

 Kiinig in a communication to the Physiological Society, pre- 

 viously reported in Nature (vol. xxxviii. p. 464). In the dis- 

 cussion which ensued, the President spoke on the sensation of 

 light derived from the resting retina {Eigenlicht). In connection 

 with the preparation of the new edition of his "Physiological 

 Optics," he had made experiments and calculations which showed 

 that the EigenlUht is much greater than has hitherto been 

 supposed. Taking as a standard the unit used by Konig and 

 Brodhun in their researches, the Eigenlkht has a magnitude 

 of forty to sixty such units. It is characterized by the irregular 

 brightness of the field of vision, giving rise to the .sensation of a 

 more or less coarsely punctated image with lighter and darker 

 patches; it further leads to the result that with equally small 

 intensities of illumination lai^e objects are seen more easily than 



