382 



NA TURE 



[February 15, 1900 



French and German. Many other instances might be given of 

 the thorough character of the work being done, but those cited 

 will serve to show that the alumni of the Institute receive an 

 education which is of service in assisting the development of 

 American industries. 



SOCIETIES AND ACADEMIES. 

 London. 

 Physical Society, February 9. — Annual General Meeting. — 

 Prof. Lodge, F.R.S., President, in the chair.— The following 

 officers were elected to form the Council :— President, Prof. 

 Lodge ; Vice-Presidents (who have filled the office of President), 

 Dr. Gladstone, Prof. Carey Foster, Prof. Adams, Lord Kelvin, 

 Prof. Clifton, Prof. Reinold, Prof. Ayrton, Prof. Fitzgerald, 

 Prof. Rucker, Sir W. Abney. Mr. Shelford Bidwell ; Vice- 

 Presidents, Mr. Blakesley, Mr. Boys, Prof. Everett, Mr. 

 Griffith ; Secretaries, Mes.srs. H. M. Elder and W. Watson ; 

 Foreign Secretary, Prof. S. P. Thompson ; Librarian, Mr. W. 

 Watson ; Treasurer, Prof. Callendar ; other members of Council, 

 Prof. Armstrong, Dr. Atkinson, Mr. W. Baily, Prof. Glaze- 

 brook, Mr. E. "11. Griffiths, Mr. S. Lupton, Prof. Perry, Mr. 

 Swinburne, Prof. Threlfall and Mr. J. Walker.— Prof. Lodge 

 delivered his Presidential address, on the controversy concerning 

 Volta's contact force. Those who take a metallic view of the 

 Volta contact force are accustomed to deny that the Peltier 

 evolution of heat measures the local E.M.F. existing at a junc- 

 tion ; they assert that it measures the rate at which that sanie 

 E.M.F. varies with temperature. In the thermodynamic 

 equation connecting the Peltier effect with the variation of E 

 with temperature, the E which varies is not necessarily that at 

 the junction considered, but is the total E.M.F. of the circuit. 

 The reversible heat at a specified junction is a measure of the 

 metallic E.M.F. located there. Those who say it is a temper- 

 ature variation of the E.M.F. beg the que.stion by locating 

 the whole E.M.F. of the circuit at the particular junction they 

 are considering, usually an interface of zinc and copper. At a 

 chemical junction the E.M F. is not purely thermal, and hence is 

 not measured by the Peltier effect; it is chiefly of chemical 

 origin, and is calculable from the energy of combination of the 

 materials on either side of the boundary. At a metallic 

 junction there is no such chemical potentiality. A strong 

 current may be passed across a zinc-copper junction for years 

 and no brass is formed. It is, therefore, improbable that the 

 chemical affinity of zinc for copper is the propelling influence 

 which causes the E.M.F. located at such a junction. In show- 

 ing the Volta effect experimentally, a trace of liquid can act 

 detrimentally by forming a conducting bridge between the 

 plates, across which the bulk of the electricity passes as the 

 metals are being separated. The safest and clearest mode of 

 expressing the Volta effect is that it consists in an opposite 

 charge acquired by dry zinc and copper while in metallic 

 contact, a charge which results from an E.M.F. of fixed value, 

 and is controlled solely by this E.M.F. and electrostatic 

 capacity. It is undeniable that the order of the Volta force 

 can be calculated from the differential heats of combination of 

 the metals for oxygen, although it is doubtful whether it can be 

 calculated from the heat of formation of brass. The opposing 

 sides of the old controversy used to be called contact theorists 

 and chemical theorists. Now the opposite sides are involved 

 both in contact and in chemical views. It is a question of 

 which of several contacts is the effective one, and what kind of 

 chemical action or affinity is the active cause. Is it the contact 

 and chemical affinity across the metal-metal junctions, or across 

 the metal-air junctions? The opposite sides are thus metallic 

 and dielectric. The metal-air force is of the order volts ; the 

 metal-metal force is of the order milli-volts. When a piece of 

 zinc is put in contact with a piece of copper, the oxygen atoms 

 which surround these bodies move slightly away from the 

 copper and approach slightly nearer to the zinc. These slight 

 motions produce the whole Volta effect. All that is necessary 

 for the Volta effect is the inherent film on the surlace. All the 

 rest of the gas is mere dielectric, and might be substituted by a 

 vacuum. It was proposed by Prof. Perry and seconded by 

 Prof. Armstrong that a meeting should be held to discuss the 

 address. The meeting was adjourned until February 23. 



Mineralogical Society, January 23.— Prof. A. H. Church, 

 F.R.S., President, in the chair.— Mr. E. G. J. Hartley, in con- 

 tinuation of his investigations on the constitution of the natural 



NO. I581, VOL. 61I 



arsenates and phosphates, gave the results of analyses of 

 beudantite, which lead to the new formula : 



3PbS04.2Fe(P, As)04.6Fe(OH)3. 



Prof. H. A.' Miers found by optical examination that the 

 mineral was probably not uniaxial, but pseudorhombohedral. — 

 Mr. G. T. Prior described rock-specimens from the Little 

 Island of Trinidad, S. Atlantic, which were collected by the 

 Ross Antarctic Expedition. They consisted mainly of phonolites, 

 with nephelenite and limburgite. — Mr. W. Barlow contributed 

 a paper on a new method of deriving the thirty-two classes of 

 crystal symmetry, which, it is stated, is more rigorous and at 

 the same time simpler and more concise than the solutions 

 hitherto given. — Mr. R. H. Solly exhibited crystals of dolomite 

 from the Binnenthal, in which the tetartohedral character was 

 well displayed. — Mr. A. L. Hall described new forms on 

 crystals of copper-pyrites from Cornwall. 



Geological Society, January 24. — W. Whitaker, F.R.S., 

 President, in the chair. — FossilsintheUniversity Museum, Oxford: 

 II. — On two new genera and species of Crinoidea, by Prof W. J. 

 Sollas, F.R.S. The first genus and species are founded on two 

 calyces in the University Collection and three in the British 

 Museum ; all the specimens come from the Carboniferous 

 Limestone. The arms and stem are at present unknown. The 

 genus in general character and structure recalls Platycrinus, but 

 the incorporation of the costal and distichal plates in the calyx 

 affords a very obvious distinction. The analysis of the calyx, 

 however, suggests the Melocrinidse, from the members of which 

 it is chiefly distinguished by the comparatively small size of the 

 costal and distichal plates. The new genus is a truly annectant 

 form uniting the Melocrinidae and the Platycrinidae, and may be 

 indifferently associated with either. The second genus and species 

 are founded on a specimen in the Grindrod Collection, obtained 

 probably from the Silurian rocks, but from a locality not known, 

 possibly Dudley. In general appearance it resembles an 

 elongated form of Pisocritius, particularly in its calyx, but the 

 arms are those of a Heterocrinid. This conjunction of characters, 

 though rendering necessary a revision of the definition of the 

 Pisocrinidae, cannot be regarded as bringing this family ap- 

 preciably nearer to the Heterocrinidse, which are fistulate, while 

 the Pisocrinidte, so far as known, are not. — Fossils in the Uni- 

 versity Museum, Oxford : III.— A new worm-track from the 

 slates of Bray Head, Ireland, with observations on the genus 

 Oldhamta, by Prof. W^ J. Sollas, F.R.S. The curious marking 

 known as Oldhamia have not been hitherto recorded from other 

 than the Lower Paleozoic rocks, although they have a wide 

 distribution in space, being found in Ireland, in the Ardennes, 

 in Brabant, in America, and possibly in Norway. While the 

 organic nature of Oldhamia was scarcely a matter of doubt in 

 the minds of the earlier writers, there existed a great diversity 

 of opinion as to its place in the organic world, and it was placed 

 by different observers among polyzoa, hydrozoa, and plants, 

 respectively. The microscopical observations made by the 

 author prove that Oldhamia is not the remains of an organism, 

 but merely a marking in the rock, though one which might be, 

 nevertheless, of organic origin.— Contributions to the Geology 

 of British East Africa : Part II.— The geology of Mount Kenya, 

 by Dr. J. W. Gregory. The three main zones of Kenya are 

 characterised by different geological features. The long slope 

 of the forest- belt consists in the main of volcanic ash, though 

 the remains of secondary parasitic craters occur in it. The 

 Alpine zone consists of. coarser ash, agglomerates, and tuffs, 

 interbedded with lava-flows and traversed by numerous dykes, 

 with the remains of some secondary centres of eruption. The 

 third zone, or central peak, consists of the plug which choked the 

 central vent, of beds of agglomerate, and the thick proximal ends 

 of the great lava-flows. — Contributions to the Geology of British 

 East Africa : Part III. — The eloeolite-syenite and fourchites 

 intrusive in the coast series, by Dr. J. W. Gregory. The rocks 

 described in this paper were given to the author by Mr. C. W. 

 Hobley. Mount Zombo, situated in long. 39° 13' E. and lat. 

 4° 26' S., and 1519 feet high, is a massif of coarse-grained 

 elteolite-syenite, consisting of anorthoclase, elfeolite, usually 

 allotriomorphic, and tegyrine. The rock must occur in the belt 

 of Duruma Sandstone, unless the fossiliferous Jurassic shales 

 run westward up the low valley of the Umba River. The sedi- 

 mentary series on the coast-lands of British East Africa and 

 Usambara are provisionally arranged by the author as follows : 

 (5) Pleistocene reefs, limestones, alluvium, and laterites ; (4) 

 Jurassic shales and sandstones ; Kimeridgian, Oxfordian, and 



