April 2, 1903] 



NA TURE 



5 2 7 



of a revolving commutator, which was driven by a hand 

 wheel and cord, the connections of a D'Arsonval galvano- 

 meter being simultaneously alternated by the same instru- 

 ment. The alternating currents were passed through a 

 Wheatstone bridge, in one of the arms of which was inserted 

 the electrolytic cell. 



In order to obtain the most probable results for the ratio 

 of the equivalent conductivities to their values at infinite 

 dilution, curves were drawn on squared paper between m* 

 and k/ni, and the smoothed readings taken at the required 

 jlaces. It is usual to call this ratio the coefficient of 

 lonisation, but at the high concentrations here dealt with, 

 we cannot assume that it really gives the fraction of the 

 number of the molecules which is at any moment ionised ; 

 in the light of probable changes in the ionic fluidity of the 

 liquids, and of the possible existence of complex ions, such 

 an assumption is clearly unjustified. For the sake of con- 

 venience, the results previously obtained, as well as those 

 of the experiments now described, are tabulated as the 

 equivalent conductivities at o c referred to the limiting value 

 as unity. 



In the earlier set of experiments, approximate values 

 only were obtained for the absolute equivalent conductivities. 

 From the values of the constants of the glass cells now used, 

 it is possible to calculate throughout the whole range of 

 concentration of both sets of observations the exact equiva- 

 lent conductivities of the salts investigated. 



Geological Society, March II. — Prof. Charles Lapworth, 

 F.R.S., president, in the chair. — Petrological notes on rocks 

 from Southern Abyssinia, collected by Dr. Reginald Kcettlitz, 

 by Dr. Catherine A. Raisin. The specimens were collected 

 on an expedition (in 1898-99) starting from Berbera, west- 

 ward through Somaliland and Southern Abyssinia, and turn- 

 ing northward to the Blue Nile. The crystalline rocks 

 include granite, gneiss, and hornblende-schist or foliated 

 diorite, together with more basic types. Some of the 

 gneisses exhibit pressure effects. The more basic types in- 

 clude diabase, hornblende-gabbro, and one lustre-mottled 

 hornblende-pyroxenite, resembling a picrite. The sand- 

 stones (chiefly from Somaliland and the south-east of 

 Abyssinia) are sometimes compacted into quartzites, and 

 are often ferruginous. Some of the limestones are concre- 

 tionary, others dolomitic, and several from different localities 

 are fossiliferous, containing at Jigjiga Pass Turritella in 

 great numbers. The volcanic rocks include one which is 

 practically a limburgite, many basalts, various less basic 

 volcanic rocks and several pumiceous tuffs. But the most 

 interesting are the phonolites and allied rocks, containing 

 nepheline, riebeckite, or other alkaline minerals. The 

 specimens here described may form a connecting-link be- 

 tween the volcanic rocks of other East African localities. — 

 The overthrust Torridonian Rocks of the Isle of Rum and 

 the associated gneisses, by Mr. Alfred Harker, F.R.S. 

 The chief conclusions which the author wishes to establish 

 are: — (1) That the highly disturbed region of the north- 

 west Highlands, already known to extend into the south- 

 eastern part of Skye, is further prolonged into the Isle of 

 Rum. (2) That at numerous places along the disturbed 

 belt which borders the principal mountain-group of the 

 island, the Tertiary plutonic intrusions assume the character 

 of well-banded gneisses, comprising alternations of different 

 lithological types. (3) That these complex gneisses were 

 formed mainly by fluxion in a heterogeneous mass, the 

 heterogeneity being due to the inclusion and incorporation 

 in a granitic magma of relics of ultrabasic and basic rocks. 

 Zoological Society, March 17.— Mr. G. A. Boulenger, 

 F.R.S., vice-president, in the chair. — Mr. Oldfield Thomas 

 exhibited the skin of a monkey from Kwei-chow, China, 

 which appeared to represent a new species of Rhinopithecus. 

 Mr. Thomas also exhibited adult and young examples of a 

 new bush-duiker from British East Africa, which he pro- 

 posed to call Cephalophus ignifer. — Mr. J. T. Cunningham 

 read a paper in which were described experiments he had 

 made on two cocks of the long-tailed Japanese fowls in his 

 possession, to ascertain what effect the artificial treatment 

 asserted by some to be practised by the Japanese fanciers 

 would have. The two birds had been hatched on the same 

 date, January 13, 1901. One of the birds was left to nature, 

 except that the tail was tied up in paper when the bird was 

 at liberty, to keep the feathers from injury. In this bird 



NO. 1744, VOL - 67] 



the longest feather was 2 feet 45 inches in length in 1902, 

 and growth ceased in March, and the feathers were moulted 

 normally in the following autumn. In the other bird the 

 feathers were stroked every day between the finger and 

 thumb, so as to pull slightly on the roots. In this specimen 

 growth continued until the middle of July, and a length of 

 more than 2 feet 9 inches was attained in some of the 

 feathers of the first adult plumage. The author considered 

 still more important the fact that ten of the feathers came 

 out under the treatment, and that successors to these 

 immediately grew again, and continued to grow through 

 and beyond the following moulting season. The author 

 concluded that the great length of feather and suppression 

 of the moult were produced by the Japanese fanciers in the 

 same way, by thus stimulating the feathers and extracting 

 them when or before they had completed their growth. — A 

 communication was read from Sir Charles Eliot, K.C.M.G., 

 in which two new genera (Ceratophyllidia and Pleuro- 

 phyllidiella) and five new species were described, and notes 

 given on some already known forms. — Mr. W. P. Pycr-aft 

 read a paper on the osteology of the Cuculiformes = Cucu- 

 lidae+Musophagidae, in which he showed that the isolated 

 position which this suborder held among the Coraciomorphse 

 was as evident from a study of the osteology of the group 

 as from other points of view. 



Manchester. 

 Literary and Philosophical Society, March 17. — Mr. 

 Charles Bailey, president, i/i the chair. — Mr. J. Cosmo 

 Melvill exhibited two letters written by Linnaeus which had 

 recently been rediscovered after being missing for more than 

 eighty years, together with a Wedgwood plaque of Linna?us, 

 given to him by Sir Joseph Hooker, with the information 

 that it had been pronounced by Dr. Solander to be " a better 

 likeness of his master than any ever painted." — Prof. W. 

 Boyd Dawkins exhibited a series of mammalian remains 

 from a cavern at Doveholes, near Buxton. He said that 

 the remains belonged to the Pliocene age, and that this was 

 the only cave in Europe which had yielded remains of that 

 period. 



Paris. 

 Academy of Sciences, March 25. — M. Albert Gaudry 1 

 the chair. — On Abelian functions with complex multiplica- 

 tion, by M. G. Humbert. — A study of the combination of 

 carbonic acid with potassium hydride, by M. Henri 

 Moissan. The formation of potassium formate from 

 potassium hydride and carbon dioxide has been indicated 

 in a previous paper ; it is now shown that the presence of 

 a trace of moisture plays an important part in this synthesis. 

 With perfectly dried materials, there is no reaction under 

 a temperature of 54 C, but the amount of water vapour 

 given off by ice at — 85 C. is sufficient to start the reaction, 

 and in presence of moisture the reaction is practically in- 

 dependent of the temperature. — On the physiological causes 

 which determine the constitution of the mollusc type, by 

 MM. Edmond Perrier and Ch. Gravier. — On the seat and 

 the nature of the hypnagogic images, by M. Yves Delage. 

 The question as to whether the hypnagogic images are re- 

 tinal or cerebral has been much discussed ; the author pro- 

 poses a simple criterion ; these images are retinal if they 

 follow the movements of the eyes, or cerebral if they do not. 

 From an experimental study the conclusion is drawn that 

 the former is the case. — On waves in the midst of a vitreous 

 medium affected with viscosity ana very slightly deformed, 

 by M. P. Duhem. — On a new kind of light, by M. R. 

 Blondlot. It has been shown in previous papers that the 

 radiation from a focus tube, filtered from light rays by pass- 

 ing through a thin sheet of aluminium or black paper, proves 

 to be polarised when examined with a small spark, and the 

 plane of polarisation is rotated by quartz or sugar. It has 

 now been found that a rotation of the plane is also produced 

 when the rays are passed through a Reusch mica pile. A 

 single sheet of mica produces elliptical polarisation, thus 

 indicating that these rays are liable to double refraction. 

 But if this is the case, there should also be simple refraction. 

 Using a small spark as detector, the refraction of these rays 

 by a prism was clearly made out, and an attempt to con- 

 centrate the rays by means of a quartz lens was also 

 successful. These effects cannot be due to the X-rays, since 

 the latter undergo neither refraction nor reflection. These 

 results indicate the existence of a new set of radiations 



