566 



NATURE 



lApril lo, 1884 



weight ensues. With i-ure nitrate, to which we finally recurred, 

 the risk is much less. 



The actual weights of depo'iled silver were usually from 2 to 

 3 grms., and, so far as the mere weighings are concerned, should 

 have been correct to 1/10,000. Di.ccrepancies three or four 

 times as great as this are, however, actually met with, whether 

 due to retention of salt or to loss of metal it is difficult to say. 

 The final number, expressinj; in C.G.S. measure the electro- 

 chemical equivalent of silver, is a little lower than that (fii9 

 X 10"-) given on a previous occasion [Caml/ri/^^e Proceedings 

 for November 26, 1SS3). It approximatis clo ely to I'llS 

 X lo~-, and is tints in precise agreement with the number an- 

 nounced within the last few weeks by Kohlrausch, viz. \ 11S3 

 X 10"". Its substantial correctness can therefore hardly be 

 doubted, more especially as it does not differ very much from 

 the number (I'I24) obtained by Mascart. In terms of practical 

 units, we may say that the ampere current deposits per hour 

 4"025 grms. of silver. 



When we are provided with means for the abiolute measure- 

 ment of cuiTents, the determination of electromotive force is a 

 very simple matter if we assume a knowledge of absolute resist- 

 ance. A galvaivic cell is balanced against the known cifiference 

 of potentials generated by a known current in traversing a known 

 resistance. The diffiiulty relates entirely to the pieparation and 

 definition of the standard cells. A considerable nnraber of Clark 

 cells have been set up and tested at intervals during the last six 

 months, and their behaviour has been .satisfactory, the extreme 

 range after the first ten days) not much exceeding i/iooo. A 

 modified forin of cell, in which the solid zinc is replaced by an 

 amalgam, is at present under trial. 



In Mr. Latimer Clark's own determination the B.A. unit is 

 assumed to be correct, and the E.M.F. of the cell at 15° C. was 

 found to be i"457 volt. On the same assumption we obtain the 

 not greatly differing value f453 volt. If we take the true value 

 of the B.A. unit as '9867 ohm, i '453 will be replaced by i'434. 



Experiments are also in progress to determine in absolute 

 measure the rotation of the plane of polarisation of light in 

 bisulphide of carbon under the action of magnetic force. Of the 

 results obtained byGoidon a.d Becquerel, differing by about 

 9 per cent., our preliminary measurements tend rather to confirm 

 the former. 



Mathematical Society, April 3. — Prof. Henrici, F.R.S., 

 president, in the chair. — The Rev. A. C. E. Blomfield was 

 admitted into the Society. — The following communications were 

 made: — On double algebra, by Prof. Cayley, F.R.S.— On the 

 homogeneous and other forms of equation of a plane section of a 

 surface, by J. J. Walker, F.R.S. — A direct investigation of the 

 complete primitive of the equation F(jc, y, z, /, q\ = o, with a 

 way of remer.ibering the auxiliary system, by J. W. Russell. — 

 On electrical oscillations and the effects produced by the motion 

 of an electrified sphere, by J. J. Thomson. 



Chemical Society, March 31. — Anniversaiy Meeting. — Dr. 

 W. II. Perkin, F. R.S., president, in the chair. — The President 

 read his annual address. The number of Fellows is at present 

 1324. During the past twelve months the Society has lost by 

 death nineteen Fellows, including Sir C. W. Siemens, Messrs. 

 W. Spottiswoode, J. T. Way, and J. Young. After briefly 

 alluding to the more important advances in chemical science, 

 the president drew attention to the fact that the number of 

 original papers read before the Society had steadily decreased 

 since 1881, notwithstanding the steady increase in the number of 

 Fellows, and the greater facilities for the study of chemistry now 

 offered by the numerous laboratories recently opened. The 

 Longstaff Medal was awarded to Mr. O'SulIivan. The follow- 

 ing Officers and Council were elected : — President : Dr. W. H. 

 Perkin, Ph.D., F.R.S. ; Vice-Presidents: Sir F. A. Abel, 

 Warren De La Rue, E. Frankland, J. H. Gilbert, J. H. filad- 

 stone, A. W\ Hofmann, W. Odling, Sir Lyon Playfair, H. E. 

 Roscoe, A. W. Williamson, P. Griess, G. D. Liveing, E. 

 Schunck, T. E. Thorpe, A. Voelcker, W. Weldon ; Secretaries : 

 H. E. Armstrong, J. Millar Thomson ; Foreign Secretai-y : H. 

 Mijller ; Treasurer : W. J. Russell ; Members of Council : E. 

 Atkinson, H. T. Brown, T. Camelly, M. Carteighe, R. J. 

 Friswell, W. R. E. Hodgkinson, D. Howard, F. R. Japp, R. 

 Meklola, R. Messel, C. O'SulIivan, C. Schorlemmer. 



Geological Society, March 22. — Prof. T. G. Bonney, 

 F.R.S., president, in the ch.air. — The Rev. Frank Ballard, 

 M.A., was proposed as a Fellow of the Society. — The following 

 communications were read : — On Rhytidostms capensis, Owen, a 



Labyrinthodont Amphibian from the Trias of the Cape of Good 

 Hope, by Sir Richard Owen, K.C. B., F.K.S. The author 

 first noticed the discovery of certain forms of Amphibia belong- 

 ing to the genera Labyrinlhodon, Brachyops, Pelrop/iryiu; and 

 Rhinosaiirus, and called attention to certain typical peculiarities 

 in the structure of the teeth, the form of the bony palate, and 

 the double occipital condyle. An imperfect cranium of the 

 species now described as R hytidosteus capensis w as procured by 

 Mr. Heer in the Orange Free .State from the Tri.asof Swanopol, 

 Beersheba, and deposited by him in the Bloemfontein Museum. 

 This specimen, which was brovight to England and submitted to 

 the author by Dr. Exton, consists of the anterior portion of the 

 skull with part of the mandible attached. The general form is 

 batraclioid, and one of the hinder palatovomerine teeth, on 

 being examined microscopically, exhibited the characteristic 

 labyrinthodont structure. The surface of the skull, and the 

 characters of the premaxillary, na-al, frontal, and prefrontal 

 bones were described. Tiie parietals and postfrontals are im- 

 perfect, the hinder part being lost. The rami of the mandible 

 are also imperfect behind, but a broken fr.agment shou-s the 

 articular surface. The vomerine bones were also decribed, 

 with the posterior nostril and the teeth before and behind this 

 opening. The breadth of the bony palate at its hinder fractured 

 border is 5 inches ; the length of the part preserved 4^ inches ; 

 the mandible, when perfect, was probably from 1 1 inches to a 

 foot in length. The author also gave an account of the dentition 

 wielded by the premaxillary, maxillary, vomerine, palatine, and 

 mandibular bones. The author pointed out that the type of air- 

 breathing vertebrates to which the present genus belongs reached 

 its highest development in the Triassic period in Britain, Russia, 

 North America, Hindostan, and South Africa. The only known 

 antecedent form from which the labyrinthodont structure of 

 tooth might have been derived is a genus of fishes named Den- 

 drodits^ in the Old Red Sandstone. The Liassic Ichthyosaiirs 

 also .show some similarity in tooth-structure ; but in them there 

 is far greater simplicity. — On the occurrence of antelope-remains 

 in Newer Pliocene beds in Britain, with the description of a new 

 species, Gazella anglica, by E. TuUey Newton, F.G. S. — A 

 comparative and critical revision of the Madreporaria of the 

 White Lias of the Middle and Western Counties of England, 

 and of those of the Conglomerate at the base of the South-Wales 

 Lias, by Robert F. Tomes, F.G.S. 



Zoological Society, April i. — Prof. W. H. Flower, LL.D., 

 F.R.S., president, in the chair. — Prof. Flower exhibited and 

 made remarks on a series of skulls of the Bottle-nosed Whale 

 {Hyprroodon rtw/raftw), illustrating the various stages presented 

 by this animal as regards the conformation of its skull in the 

 different ages of both sexes. Prof. Flower also exhibited, on 

 behalf of Messrs. Langton and Bicknell, a specimen of spermaceti 

 obtained from the head of the Hyperoodon. — Mr. Sclater ex- 

 hibited and made remarks on specimens of the eggs of two 

 species of Testudinata ( Testudo elephantopus, and C/ielys mata- 

 matd) recently laid by animals living in the Society's Gardens. 

 — Mr. R. Bowdler Sharpe exhibited and made remarks on a 

 Red-throated Pipit (Anthiis cervinus) caught near Brighton in 

 March last. Mr. .Sharpe exhibited at the same time an example 

 of the true W.ater-Pipit (.<4k/^;m .r/jwo/f^/a) captured at Lancing, 

 in Sussex, in March 1877. — Prof. E. Ray Lankester, F.R.S., 

 exhibited and made remarks on a large living Scoqjion {Buplivs 

 cyaneus) from Ceylon. — A communication was read from Prof. 

 T. Jeffrey Parker, being the first of a series of studies in New 

 Zealand Ichthyology. The present paper gave a description of 

 the skeleton of Rigalecus argenteiis. The species was founded 

 on a specimen cast ashore at Moeraki, Otago, in June 1883. — 

 A communication was read from Viscount Powerscourt, F.Z.S., 

 containing an account of the origin and progress of the herd of 

 Japanese Deer at Powerscourt. — A communication was read 

 from Mr. G. A. Boulenger, giving the diagnoses of some new 

 Reptiles and Batrachians from the .Solomon Islands, collected 

 and presented to the British Museum by Mr. H. B. Guppy, of 

 H.M.S. Lark. — A communication was read from Mr. C. O. 

 W^aterhouse, containing an account of the coleopterous insects 

 collected by Mr. H. O. Forbes in the Timor- Laut Islands. — Mr. 

 F. D. Godman, F.R.S., read a paper containing an account of 

 the Lepidoptera collected by the late Mr. W. A. Forbes on the 

 banks of the Lower Niger, the Rhopalocera being described by 

 Messrs. F. D. Godman and O. Salvin, and the Heterocera by 

 Mr. H. Di-uce. The species of butterflies were fifiy in number, 

 and comprised representatives of all the families of Rhopalocera 

 hitherto known from Tropical Africa, except the Erycinidfe, a 



