Jan. lo, i< 



NA rURE 



253 



diameter of over 500 miles, that she resembles the moon in he'' 

 albedo, hence lacUs an appreciable atm. sphere and water, tha' 

 the irregularities of her light indicate a very rouyh surface and 

 rotation on her axis ; lastly, ihat what is true of Ve^ta is likely 

 to be true, mtilalis mutandis, of the other asteroids. — On a new 

 form of selenium cell and some electrical discoveries made by 

 its use, by Charles E. Fritts. This new form of selenium cell 

 has the following properties : — (i) its resistance can be made as 

 loH- as desired, do^n to nine ohms ; (2) the light is made to 

 strike the cell in the same plane as the current ; (3) it is far 

 more sensitive to light than any before known, one cell having 

 had fifteen times is high resistance in dark as ordinary diffused 

 daylight in a room, bince the paper was written, the author 

 announces the discovery of a new form of selenium, quite 

 CJlourless and transparent, obtaii ed und' r conditions excluding 

 everything but selenium. — The Ischian earthquake of July 28, 

 1883, by C. G. Rockwood, jun. The author concludes that this 

 disturbance had its orgin in a rupture taking place along an old 

 volcanic fissure running roughly north and south, and extending 

 r.ailially under the northern slope of Mount Epomeo ; and that 

 the cau-e of the increaed tension resulting in this ru ture must 

 be referred to the residual volcanic activity which Ischia shares 

 with the adjacent mainland, rather than to any merely local 

 subsidence, as suggested by Prof. Palmieri. 



Annalen dcr Pliysik iiiiJ Cheinie, Ed. xx. No. II, 1883. — 

 R. Clauius, on the theory of dynamo-electric machines. This 

 is a remarkably clear and able paper, dealing with the funda- 

 mental points in the theory of dynamo- electric machines in a 

 masterly way, and introduces several new notions requiring the 

 determination of the arbitrary constants in different machines. 

 The questions of self-induction and mutual induction between 

 diiTereiit segments of the armature receive special attention. The 

 author promises a further paper with applications of the equa- 

 tions. — L. Sohncke ani A. Wan^erin, on interference-pheno- 

 mena in thin and pirticnlarly in wedge-shaped films. This 

 paper is a continuation of one in last month's issue, giving new 

 fundamental formuk'e for Newton's rings and other interference- 

 phenomena of thin films. — B. Hecht, on the determination of 

 the axis-ratios of the elliptic paths in elliptic polarisation in 

 quartz. A discussion of furmulre of Cauchy, Lommel, Voigt, 

 and lamin, in reference to the .-luth-r's experiment"^. — W. Vuigt, 

 on the theory of light : a polemic again-t llerr Lommel respect- 

 ii g the latter's views on the possible intermolecular friction of 

 the luminiferous ether. — H. Wild, on the api^lication of bis 

 photometer as a spectrophotometer ; this instrument, constructed 

 by Hermann and Pfister, of liern, contains a slit, a calc-spar 

 rhnmbohedron, a Foucault prism, a second rhombohedron, a 

 selenite plate, a Nicol prism, a pair of adjustable gkass prisms, a 

 5-prism Amici direct-vision prism, and sundry lenses. The light to 

 be examined has to pass through these successively. — Researches 

 on forced vibrations of plate- ; part ii., on vilirations of square 

 plates, by A. Elsas. This paper, which is accompanied by a set of 

 forty-nine figures, is in continuation of a previous research on 

 forced vibrations of round plates. The author points out that we 

 already have the w;ll-known researches of Chladid and Wheat- 

 stone on the figures due to natural vibrations of such plates. 

 The aim of this research was to ascertain whether Savart's rule, 

 that the forms of the forced vibrations merge into one another 

 by a perfectly continuous series of modification^', is true for 

 square plates; whether the figures corresponding to forced 

 vibrations agree with those of the free vibrations of the same 

 pitch ; and whether the legitimacy of Wheatstone's method of 

 superposition is confirmed or disallowed. The most important 

 of all the results is that it is impossible for a square plate to 

 vibrate in response to any time whatever, higher than its own 

 fundamental, that may be forced upon it. — On Boltzmann's 

 theory of elastic reaction, by Prof. E. Riecke ; a mathematical 

 discussion of Boltzmann's equations. — On aqueous solutirin^", by 

 J. A. Gro5han=. A discussion of the dependence of the density 

 of the solution on the quantity and molecular CDnslitution of the 

 soluble substance. — Measurement of the quantity of electricity 

 pi'oduced by a Zamboni's pile, by Prof. E. Riecke. The values 

 were calculated from currents iraver.-ing a long-coil galvano- 

 meter and a very high resistance. — On the galvanic-temperature 

 coefficients of steel, rod-iron, and cast-iron, by V. Strouhal and 

 C. barus. For steel this coefficient diminishes as the hardness 

 of tempering increases, while the specific resistance increases 

 with the hardness. Glass-hard steel has about three times the 

 specific resistance of soft steel. — On the relation between vis- 

 cosity and electric resistance of solutions of salts in various 



solvent media, by E. Wiedemann. There appears to be no such 

 relation as has been conjectured to exist. — On Arabian measure- 

 ments of specific gravity, by E. Wiedemann. — Simplifications in 

 experimenting with the air-pump, by K. L. Bauer, suggests the 

 expedient already well known in England, of placing a sheet of 

 soft caoutchouc under the receiver of the pump instead of 

 greasing its rim ; also similarly between the edges of the 

 Madgebui-g hemispheres. Gutta-percha paper is suggested as a 

 substitute for bladder to be burst by air-pressure. 



SOCIETIES AND ACADEMIES 

 London 

 Chemical Society, December 20, 1883. — Dr. W. H. 

 Perkin, F. R.S., president, in the chair. — The following gentle- 

 men were elected Fellows of the Society: — W. P. Bloxam, A, 

 Cobb, J. C. Chambers, A. E. Ekin--, F. P. Haviland, F. 

 Keeling, W. H. R. Kerry, J. J. Pilley, M. Percy, J. Phillips, 

 A. W. Rogers, W. J. Saint, G. Smith, A. Smithells. The 

 following papers were read: — Researches on the gums of the 

 arabin group, by C. O'Sullivan. Part I. Arabic acid ; its com- 

 positi-'U, and the products of its decomposition. In this most 

 important paper the author has studied the action of dilute 

 sulphuric acid upon arable acid. The arable acid was prepared 

 by the method of Neubauer, and the sulphuric acid was allowed 

 to act for various lengths of time from fifteen minutes to several 

 hours. The molecule of arabic aciJ, CjdHjjjO-j, is broken 

 down, a series of eleven acids of gi".adually decreasing molecular 

 weight (differing by CgHj^Os) having been isolated, and the 

 barium ^alts formed and analysed ; the lowest acid is CoaHajOg.,, 

 and is comparatively stable; these acids the author calls o, J8, 

 &c., arabinosic acids. Simultaneously a series of sugars having 

 the compo ition C6fri..O|j is formed of gradually decreasing 

 optical activity, v\hi>-h the author names a, ;8, 7, and 5 arabino e. 

 Arabic acid is 1 he chief constituent of all the la;vorolatory gums, 

 but other acids are present which bear a simple relation to 

 it. In a future piprr the author promises an account of the 

 dextrorotatory and optically inactive gums, the acids of which 

 are built up in the same manner as arabic acid. — On the decom- 

 position of ammonia by heat, by W. Ramsay and S. Voung. 

 This decomposition commences about 500", and is nearly equal 

 in extent with porcelain, glas», iron, and asbestos, but at 780° 

 ammonia is almost completely decomposed by passing through 

 an iron tube. Copper, when heated, is not so active. — On the 

 halogen compounds of selenium, by F. P. Evans and W. Ram- 

 say. — On the preparation of pure chlorophyll, by A. Tschirch. 

 This ."-ubstance is obtained by the action of zinc du t on 

 chlorophyllan (Bot. Zeit., 1882, 533) ; its spectrum is identical 

 with that given by living leaves. 



Zoological Society, December 18, 1883.— Prof. W. H. 

 Flo«er, F.R..S., president, in the chair. — Dr. F. Leuthner read 

 an abstract of a memoir which he had prepared on the Odonto- 

 labini, a subfamily of the Coleopterous family Lucanid;"e, re- 

 markable for the polymorphism of the males, while the females 

 remained very similar. The males were stated to exhibit four 

 very distinct phases of development in their n andibles, which 

 the author proposed to term "priodont," "amphiodont," "meso- 

 dont," and "telodont." These forms were strongly marked 

 in some species ; but in others were c nnected by insensible 

 gradations, and had been treated by the earlier authors as dis- 

 linct species. The second part of the memcir contaim.d a 

 monograph of the three known genera which constitute the 

 group Odontolabi'.i. — Mr. E. B. Poulton, F.Z.S., read a me- 

 moir on the structure of the tongue in the Marsupialia. The 

 tongues of species of nearly all the important groups of thi- sub- 

 class were described in detail. It was found possible to classify 

 the toniiues in three divisions. Of these, Habnattit-us was the 

 type of the lowest, Plialaiigista of the intermediate, and Pera- 

 vicles of the most advanced, division. — Mr. J. Wood-Mason, 

 F.Z.S., read a paper on the Embiidae, a little-known family cf 

 insects, on the structure and habits of which he had succeded in 

 making >ouie investig.ations during his recent re-idence in India. 

 He came to the conclusion that the Embiida; undoubtedly 

 belong to the true Orthoptera, and are one of the lowest terms 

 of a series formed by the families Acridioidese, Locustids, 

 Gryllida', and Phasmatidte. — Mr. G. A. Boulenger, F.Z.S., 

 read an acount of a collection of frogs made at \'urimagua?, 

 Huallaga River, Northern Peru, by Dr. Hahnel. The collec- 

 tion contained examples of eighteen species, eight of which were 



