500 



NA TURE 



[March 26, 1885 



The motor thus governed rotates a shaft on which is a copper 

 disk and two pulleys. The copper disk is placed between the 

 poles of a large electro-magnet : and the second pulley serves to 

 give motion by means of an india-rubber band to a replenisher 

 whose dimensions are determined by the special conditions of 

 the experiment for which the apparatus is to be employed. The 

 regulator, mounted on a box in which is a condenser, consists of 

 a fixed and movable disk, the latter suspended from a spiral 

 spring and carrying a wire across its back turned down at its 

 two ends. The disks are connected with the poles of the con- 

 denser, the movable one being put to earth. By means of a 

 Weber suspension arrangement mounted on the top of a guard- 

 hole which protects the spiral spring from currents of air, the 

 attracted disk can be adjusted so that when the difference of 

 potentials arrives at the required value, the wire dips into two 

 mercury cups and so short-circuits a high resistance. By this 

 mean, a strong current is allowed to flow through the electro- 

 magnet and act as a brake on the copper disk ; this causes the 

 velocity of the engine to change and a replenisher to revolve 

 more slowly. When the potentials have fallen sufficiently by 

 leakage or otherwise, the contact at the mercury cups is broken 

 and the motor is enabled to rotate at a higher rate of speed. 

 By this means the | otential difference is kept between certain 

 limits depending on the sensibility of the arrangement, and this 

 is increased by having the disks close together and the contact 

 points made of aluminium instead of platinum. Such an appa- 

 ratus is of use in maintaining condensers, &c. , subject to leakage 

 at a constant high potential. 



Paris 

 Academy of Sciences, March 16. — M. Bouley, President, 

 in the chair. — Reaction of bromine on the chlorides and on 

 hydrochloric acid. A new class of perbromides by M. Berthelot. 

 Fresh experiments made by the author show that the reaction of 

 bromine on the chlorides always liberates heat in the same way 

 as the inverse reaction. In both cases the transformation of the 

 system is always exothermic. Hydrochloric acid and highly 

 concentrated chlorides dissolve bromine in large quantities with 

 liberation of heat, attesting the existence of combinations formed 

 by addition (perbromides of chlorides). — A morphological com- 

 parison of Limax (L. Agrestis. Cimereus and Gagates) with 

 Testacella (T. haliotidea and Maugey), by M. H. de Lacaze- 

 Duthiers. — On the solubility of the sulphurets of carbon and of 

 chloroform, by MM. G. Chancel and F. Parmentier. The 

 solubility of the sulphuret of carbon in water is shown to 

 diminish according as the temperature is raised. But that 

 of chloroform presents a decreasing solubility from o° to 

 about 30° C, thenceforth increasing towards its boiling- 

 point. — On the influence of the perturbations in deter- 

 mining the orbits of celestial bodies, by M. E. Vicaire. — 

 A reply to M. Boiteau on the treatment of phylloxera and its 

 winter eggs by washings and sulphur, by M. P. de Lafitte. — 

 Records of the Scientific Mission to Cape Horn (1882-83) ; 

 Vol. ii. Meteorology, by M. J. Lephay. — Note on the Abelian 

 functions, by M. H. Poincare. — On the theory of matrices, by 

 M. Ed. Weyr. — On the canonical types of the ternary quadratic 

 forms of differentials whose discriminant is null, by M. (',. 

 Konigs. — On the electric differences between fluids, and on the 

 part played by the atmosphere in the electrometric measurement 

 of these differences, by MM. E. Bichat and R. Blondlot. — A 

 thermo-chemical study of the fluosilicate of ammoniac : action 

 of the fluoride of silicium on the fluoride of ammonium, and on 

 ammoniac, by M. Ch. Truchot. — Description of a new process 

 for hardening plaster of Paris, by M. Julhe. By the process 

 here described a plaster is produced which may be substituted 

 for wood in floorings, being equally durable and four times 

 cheaper than oak. — Bromuretted substitution of phenolic hy- 

 drogen : bromuretted tribromophenol, by M. E. Werner. — On 

 Fromherz's fluid, by M. E. J. Maumene. — On the chemical 

 composition and therapeutic properties of Artemisia gallica, 

 Wildenow, by MM. Ed. Ileckel and Fr. Schlagdenhauffen. — 

 Physiological action of the hexahydride of j3-colladine or iso- 

 cicutine, by MM. Rochefontaine and CEchsner de Coninck. 

 From experiments made on the frog and guinea-pig the authors 

 find that this substance possesses a physiological action analogous 

 to that of the alkaloid of hemlock (Cicuta). Hence they propose 

 the alternative name of " isocicutine," recalling at once its chief 

 chemical and physiological properties. — Definition, classifica- 

 tion, and notation of colours, by M. J. Charpentier. A system 

 of notation and classification is suggested, by means of which a 

 thousand colours may be formulated by the series of natural 



numbers from o to 999, where each cipher takes a precise mean- 

 ing in virtue of its position. The name of the colour would 

 simply be that of the number symbolising it, and the system 

 might be called the "cubic classification,'' from the geometri- 

 cal representation by which it may be best figured. — On 

 the glands and lymphatic vessels entering into the constitution 

 of the organ in birds known as the purse of Labricius, by M. 

 Retterer. — On the physiological effect produced by the action of 

 turning eggs during incubation, by M. Dareste. From experi- 

 ments made with artificial incubators, the author finds that eggs 

 not turned two or three times a day all perish invariably. The 

 effect of this act on the embryo is explained, and the action of 

 the bird accounted for on strictly physiological grounds. — Ores 

 of the carbonate of zinc : their normal association with dolo- 

 mitic formations explained, by M. Dieulafait. — On the Miliolidere 

 of the Chalk formations, by MM. Munier Chalmas and Schlum- 

 berger. Idalina, Periloculina, and Lacazina, three new genera 

 from the Upper Chalk of Provence, are described and affiliated 

 to the family of the Miliolideas. — The channels and lagoons on 

 the east coast of Madagascar, by M. A. Grandidier. These 

 inlets and lacustrine formations are explained by the position of 

 the main water parting, which is usually placed about the centre 

 of Madagascar, but which the author shows is situated much 

 nearer to the east than to-the west coast. 



Vienna 

 Imperial Academy of Sciences, January 22. — On the 

 analysis of andesin of Frifail (Carinthia), by R. Maly. — On the 

 self-purification of natural waters, by F. Emich. — On the action 

 of bile acids on glutin and glutin ''peptones,' by the same. — On 

 the products obtained by reduction of nitroazoic bodies, and on 

 azonitrilic acids, by J. V. Janovsky. — On the astronomical know- 

 ledge of the South Arabian Cabyles, by E. Glaser. — On dehy- 

 dracetic acid, by L. Haitinger. — Geological researches on the 

 grauwacke formations of the North-East Alps, especially regard- 

 ing the Semering region, by F. Toula. — On the meteorological 

 observations made at the Austrian arctic station at Jan Mayen 

 during 1S82 and iS83, by A. Sobiezky. — On tide observations 

 made in 1S82-83 at Jan Mayen, by A. Bobrik. — On the survey 

 of Jan Mayen carried out by the Austrian Arctic Expedition, by 

 the same. 



CONTENTS p AGE 



Practical Physics 477 



Malayan Antiquities. By Prof. A. H. Keane . . . 478 

 Our Book Shelf:— 



" The Antananarivo Annual and Madagascar Maga- 

 zine."— Prof. M. Foster, Sec.R.S 479 



Letters to the Editor : — 



The Forms of Leaves. — Sir John Lubbock, Bart., 



M.P., F.R.S 479 



Aurora at Christiania. — Dr. Sophus Tromholt . . 479 



" Peculiar Ice Forms." — W. J. McGee 480 



Four-Dimensional Space. — S 481 



The Action of Very Minute Particles on Light. — J. 



Spear Parker 481 



Fall of Autumnal Foliage. — Rev. Alexander Irving 482 

 Human Hibernation.— Col. C. K. Bushe .... 4S2 



Bos primigenius. — Jas. Backhouse ....... 482 



The British Association and Local Societies . . . 4S2 

 Underground Noises heard at Caiman-Brae, Car- 

 ribean Sea, on August 26, 1883. By Dr. F. A. 



Forel 4S3 



Remarks on our Method of Determining the Mean 

 Density of the Earth. By Prof. Arthur Kbnig and 



Prof. Franz Richarz. (Illustrated) 484 



Saturn. By Rev. T. W. Webb. (Illustrated) ... 485 

 On Petalody of the Ovules and other Changes in a 

 Double-Flowered Form of " Dianella caerulea." 



By Dr. Maxwell T. Masters JS7 



Musical Scales of various Nations. By Alexander 



J. Ellis, F.R.S 4SS 



Notes 49° 



Astronomical Phenomena for the Week 1885, 



March 29 to April 4 493 



Geographical Notes 493 



Accidental Explosions Produced by non-Explosive 



Liquids, II. By Sir Frederick Abel, C.B., F.R.S. 493 

 Societies and Academies 49("> 



