5 2: 



NA TURE 



[April 2, 1885 



work on the Odontomithes, or birds with teeth, and contains a 

 full account of the peculiar order of mammals discovered hy him 

 during the last fifteen years in the early tertiary formations of 

 the great central plateau in Wyoming. The old lacustrine basin 

 of this region, where alone the remains of Dinocerata have 

 hitherto been found, have already yielded parts of over 200 

 individuals, which are now grouped in three genera : Dinoceras, 

 Marsh ; Tinoceras, Marsh ; and Uintatherium, Leidy. The 

 last-named appears to be the most primitive type, and Tinoceras 

 the most specialised, Dinoceras being intermediate. Of species 

 the number cannot yet be determined, but thirty more or less 

 distinct forms have already been recognised. In stature and 

 movements it appears to have resembled the elephant as much 

 as any other known type, differing from it especially in the 

 shape' of the skull, remarkably small brain, longer neck, and 

 more bent fore limbs. It was by far the largest of all known 

 Eocene animals. The paper is enriched with numerous illustra- 

 tions, and with a map showing the region of Dinoceras beds. — 

 On Taconic rocks and stratigraphy, with a geological map of 

 the Taconic region, by James D. Dana. In this paper the 

 author embodies the results of a fresh study, begun in 1882, of 

 the Taconic region extending over parts of Massachusetts, 

 Connecticut, Vermont, and New York. The rocks described 

 comprise the Taconic skirts of the Taconic range, and subordinate 

 ridges within the adjoining limestone area ; the limestone forma- 

 tions on the east and west sides of the Taconic range; and the 

 quartzite adjoining or within the limestone area. All these 

 rocks ore regarded as belonging to one system of Lower 

 Silurian age, with the Taconic"schists as the upper member of 

 the series. The map is to a scale of half an inch to the mile. — 

 Variations of latitude, by Asaph Hall. The author deals with 

 Signor Fergola's recently-proposed plan for investigating varia- 

 tions of latitude by special series of observations made with the 

 best prime vertical transit instruments on selected lists of stars. 

 A chief feature of the plan is that the work is to be mainly 

 differential, two observatories under the same or nearly the 

 same latitude co-operating. — Notes on the Jurassic strata of 

 North America, bv Charles A. White. The paper is mainly a 

 reply to the objections raised by Mr. J. F. Wliiteaves, of the 

 Canadian Geological Survey against the classification of certain 

 exposed formations frequently occurring throughout Colorado, 

 Wyoming, Dakota, Utah, and Montana, and usually referred to 

 the Jurassic period.— Meteoric iron from Coahuila, Mexico, by 

 M. T. Lupton. An analysis of a fragment of this meteoric 

 mass, weighing about 192 lbs., yielded: iron, 91 '86; nickel, 

 7-42: cobalt, 50; phosphorus, '27. — Optical projection of 

 acoustic curves, by W. Le Conte Stevens. Optical presenta- 

 tions of a concord and a discord are shown projected on a screen 

 by a simple and ingenious process. — Measurement of strong 

 electrical currents, by John Trowbridge.— Divisibility of the 

 Archaean formations in the North- West.iby R. D. Irving. The 

 region here investigated occupies, as indicated by the accom- 

 panying sketch-map, a tract some sixty miles in length between 

 Lake Numakagon, in North Wisconsin, and Lake Gogebic, in 

 North Michigan. The Archaean rocks of this district are re- 

 ferred to the Huronian and Laurentian systems. — Mineralogical 

 notes, by W. E. Hidden. Specimens are described of phenacite 

 and Xenotine, from new localities ; of Fayalite, from Colorado ; 

 of Zircon, from Canada ; and of zutile and emeralds, from North 

 Carolina. 



Nachrichten von der A'. Gesellschaft der WissenschafUn und der 

 UniversitiU zu Gottingen, August to December, 1S84. — A con- 

 tribution to the theory of the' absorption of light in crystals, by 

 W. Voigt. — Remarks on the theory of the cycloid and on all 

 forms of cycloidal curves, by A. Enneper. — Researches on the 

 symmetrical relations and elasticity of crystals, by B. Minne- 

 gerode. — On the histology of the Asteridas, by Dr. Otto 

 Hamann. — On some derivatives of urea, by R. Leuckart.— On 

 the preparation of orthodinitrobenzol in large quantities, by 

 Paul Jannasch. — A contribution to the theory of complex dimen- 

 sions developed from n unities, by K. Weierstrass. — Researches 

 on the optical structure and properties of leucite, by C. Klein. 

 — On some noteworthy archaeological object in Treves, by 

 Friedrich Wieseler. — Remarks on Gauss's algebraic series, by 

 J. Thomae. — On the titrimetric analysis of urea, by Dr. Th. 

 Pfeiffer. — On the development of the reproductive organs in 

 Limax agrestis, by J. Brock. — On the classification of the genus 

 Loligopsis, Lam. {Leachia Lesueur), by J. Brock. — Remarks on 

 the Acta Mathrmatica, edited by Dr. Gbsta Mittag-LefHer, by 



Ernst Schering. — On the electro-magnetic rotation of a fluid, by 

 Eduard Riecke. — On the inflexion of the present participle and 

 comparative in Meeso-Gothic, by Leo Meyer. 



SOCIETIES AND ACADEMIES 

 London 

 Royal Society. March 10. — "On 'Transfer-resistance' in 

 Electrolytic and Voltaic Cells.'' By G. Gore, I.L.D., F.R.S. 



The existence of this phenomenon has been a matter of doubt 

 ever since the year 183 1, and the question has been examined by 

 many investigators. In the present paper are described a series 

 of methods by means of which its reality has been determined. 

 Other methods are given for measuring the amounts of such 

 "resistance," either collectively at the two electrodes of an elec- 

 trolytic cell, or separately at each electrode. Modes of obviating 

 the interference of polarisation, and of securing success in the 

 measurements, are also described. 



The influence of various circumstances upon the phenomenon 

 were investigated — viz. strength and density of current ; total 

 resistance ; density of current and size of electrode ; composition 

 of the electrolyte ; strength of ditto ; combined electrolytic cells ; 

 temperature ; and chemical corrosion. The relations of the 

 phenomenon to size of plate in voltaic cells, to the positive and 

 negative plates respectively, and to strength of current in those 

 cells, were also examined, and the results are given. 



The following are the chief facts established by this research : — 

 That a species of electric "resistance," distinct from that of 

 polarisation and of ordinary conduction-resistance, varying greatly 

 in amount in different cases, exists at the surfaces of mutual con- 

 tact of metals and liquids in electrolytic and voltaic cells. That 

 this " resistance " varies largely in amount with different metals 

 in the same solution, and with the same metals in different 

 solutions ; in dilute solutions of mineral acids of different 

 strengths, or of different temperatures, and is usually small with 

 easily corrodible metals which form quickly soluble salts, and 

 large with those which are not corroded ; and is disguised in 

 the case of those which by corrosion form insoluble salts. 



The results of the experiments also show that the same voltaic 

 current was "resisted" in different degrees by every different 

 metal when employed as an anode, and when used as a cathode ; 

 also by the same metal when used as an anode and cathode 

 respectively : and that the proportions of such " resistance " at 

 an anode and cathode of the same metal varied with every 

 different metal in every different electrolyte (and strength of 

 electrolyte), and at every different temperature ; and that the 

 resistance at the anode was usually smaller than that at the 

 cathode ; in some cases, however, where a film was formed upon 

 the anode, an apparently reverse effect occurred ; that a current 

 from a given positive plate of a voltaic cell was differently 

 resisted by every different metal used as a negative plate in that 

 cell ; and that by rise of temperature "transfer-resistance" was 

 usually and considerably reduced. 



They further show that this species of "resistance" was 

 largely reduced by increasing the strength of current ; and was 

 thus conspicuously distinguished from ordinary conduction- 

 resistance of the electrolyte. In consequence of this effect, 

 "transfer-resistance" was greatly influenced by every circum- 

 stance which altered the ordinary resistance, and thereby the 

 strength of current. The usual effect of diminishing the density 

 of current alone, by enlarging both the electrodes and keeping 

 the strength constant, was to diminish the "transfer-resist- 

 ance ; " and of enlarging one only, was to diminish it at that 

 electrode and increase it at the other, the effect being greatest at 

 the altered electrode ; but the influence of density was very 

 much smaller than that of strength of current. The current was 

 usually less " resisted," and larger with a small positive plate 

 and a large negative one, than with those sizes reversed. Altera- 

 tions of size or kind of metal at one plate of an electrolytic or 

 voltaic cell affected the " transfer-resistance " at the other, by 

 altering the strength and density of the current. 



"Transfer- resistance," therefore, appears to vary, not only 

 with every physical and chemical change in the metals and 

 liquids, but also with every alteration in the cuiTent. Such 

 "resistance" throws light upon the relative functions of the 

 positive and negative plates of voltaic cells, and illustrates the 

 comparatively small influence of the negative one in producing 

 strength of current. Nearly all these conclusions are based upon 

 results represented by average numbers obtained by series of 

 experiments. 



