252 



NATURE 



{Jan, 24, 1878 



time ago by officers of the Russian general staflF, who have had 

 the opportunity of making use of it on travels. 



M. Chikoleff, who has made, at St. Petersburg, several 

 experiments on electrical lights, by order of the Ministry of War, 

 confirms, in the ninth number of the Journal of the Russian 

 Chemical and Physical Societies, the results of the experiments 

 of Tyndall. He observes also, that a galvano-plastie copper 

 coating of the carbon proves to be very useful. 



At a recent lecture held at the Rudolphinum, at Vienna, 

 before a large audience. Dr. E. Lewy proved that the human 

 skin is completely impenetrable for the chemical contents of 

 mineral waters, and that therefore the explanation of the efTects 

 of baths in these waters, at the numerous bathing-places, has to 

 be sought exclusively in the domain of physics and not in that 

 of chemistry. This important discovery annuls all common 

 views regarding the bathing cures effected by the various mineral 

 springs, and explains in the simplest manner that, from a chemical 

 point of view, the action of the most different waters must be> 

 one and the same. 



The French Government has recently appointed a mixed 

 commission of leading scientific men and engineers for the pur- 

 pose of making a thorough examination into the best means 

 of preventing the explosions of firedamp in coal-pits. Among 

 its members are MM. Daubree, Berthelot, Thenard, and 

 Hebert, of the Academy of Sciences, Professors Bert, Burat, 

 Haton de la Goupilliere, Fouque, and other well-known names. 

 Although the French mines have suffered comparatively little in 

 this direction, the terrible disasters in our English mines have 

 taught the necessity of throwing about the miner's dangerous 

 occupation the utmost sa'eguards at the command of modern 

 science, and an active and thorough programme is being pre- 

 pared by the Commission. 



A REQUISITION has been sent to the French Ministry by the 

 Societe de Physique, asking that it should be incorporated, or 

 "reconnue comme d'utilit^ publique." It is stated that a 

 favourable reply may be expected from M. Bardoux. 



At a recent meeting of the French Physical Society, M. 



Duter presented magnets obtained by subjecting circular steel 



plates to the action of an electro-magnet terminated with a 



conical point applied to the centre of the disc. In these 



magnets the neutral line is a concentric circle of the disc, with 



R 

 radius — j. To study the free magnetism distributed over them, 



M. Duter used a small soft iron cylinder (a few centigrammes in 

 weight), fixed in the centre to the rod of an areometer floating 

 in water. The force of detachment of this was estimated by the 

 weight of water which had to be let off from the cylindrical 

 vessel containing the areometer before the contact was detached. 

 The precise instant of contact and detachment was indicated by 

 an electric signal. M. Duter thus demonstrated experimentally 

 that the quantities of free austral and boreal magnetism were 

 equal in the two portions (of contrary name) in the same plate. 

 He sought to represent by an empiric formula, the results relative 

 to forces of detachment for plates of diflferent diameter. These 

 forces depend simply on one specific coefficient variable with the 

 nature of the steel and with the thickness. 



The influence on the animal organism of breathing pure 

 oxygen gas of density corresponding to ordinary atmospheric 

 pressure, has not hitherto been adequately determined. The 

 Royal Society of Gottingen, therefore, offer a prize for new 

 researches on the subject, made both on homoiothermal, and, as 

 far as possible, on poikilothermal animals ; in these researches, 

 while certain externally visible phenomena in the animal will 

 liave to be considered, special attention is desired to be given to 



the nature of the blood and the exchange of material (excretion 

 of carbonic acid, and nature of urine). The oxygen used should 

 be carelully freed from all foreign matters apt to occur in manu- 

 facture ; while a limited (and perhaps hardly avoidable) ad- 

 mixture of atmospheric nitrogen would not compromise the 

 results. In the mathematical class, the Gottingen society desires 

 (and offers a prize for) new researches on the nature of the 

 unpolarise-1 light-ray, " fitted to bring the conceptions of natural 

 light of any origin, near (in definiteness) to those which theory 

 connects with the various kinds of polarised light." (For further 

 particulars see the Society's Nachrkhten, No. 26, 1877.) 



Hitherto water has been regarded as possessing a greater 

 specific heat than any other body, with the exception of hydrogen. 

 In a recent session of the Vienna Academy M. E. Lecher com- 

 municated the results of experiments showing that in this respect 

 water alone is surpassed by various mixtures of methylic alcohol 

 and water, which will accordingly take the second position in 

 regard to hydrogen. 



The Report of the Berlin Academy of Sciences for September 

 and October, which has just appeared, contains, among other 

 papers, " Comparison of the Tidal Heights in the East Sea from 

 1846-1875," by H. Hagen ; "Anatomy of the Appendicularia," 

 by Prof. Virchow and H. Langerhaus ; " Atomic Weight of 

 Molybdenum," by Prof. Rammelsberg ; "Movement of the 

 Electricity in Submarine and Subterranean Telegraphic Wires," 

 by Prof. Kirchhoff ; and "Catalogue of the Fishes and Amphibia 

 from Chinchoxo (Africa), presented to the Berlin Zoological 

 Museum by the Afrikanuche Gesellschaft" by Prof. Peters. 



The electromotive force produced by the flow of water through 

 capillary tubes has lately been investigated both by M. Haga 

 at Strassburg University, and by Mr. J. W. Clark at Heidelberg 

 {Pogg. Ann., No. ii, 1877). Both observers used a quadrant 

 electrometer instead of a galvanometer (as in former experiments 

 with diaphragms and capillary tubes) to measure the difference 

 of potential. This difference, according to M. Haga, is propor- 

 tional to the pressure, independent of the length of the tubes, 

 dependent on the nature of the inner surface of the tubes, in- 

 creases with the resistance of the water, and probably also with 

 the temperature. Mr. Clark finds (i) that the narrower the 

 tube the greater is the electromotive force when liquids are forced 

 through. (2) In very narrow tubes the electromotive force is 

 independent of the length ; in wider tubes it decreases with the 

 length. (3) If the inner tube-surface be coated with different 

 substances, different electromotive forces are obtained, whose 

 amounts entirely agree with Quincke's former results with regard 

 to diaphragm currents. (4) The electromotive force decreases 

 with the time ; and this whether still water or flowing water 

 occupy the tube between the experiments. If the tube be cleaned 

 anew with sulphuric acid and distilled water, the original electro- 

 motive force is re-established. (S) The seat of the electromotive 

 force is the limiting surface of the liquid and the solid tube-wall. 



The Russian newspaper published in Turkestan reports that 

 the scientific explorations in the Semirechensk District were 

 continued uninterruptedly during the year 1877. Special atten- 

 tion was bestowed upon the investigation of the line of coral 

 reefs which remained from the prehistoric Central Asian Sea. 

 This line extends from the Dalashik Mountains over the Tuluk 

 Tau and Temirlik Tau, and further eastward as far as the fron- 

 tier of the Kuldsha District. Large quantities of the finest 

 corals and beds of fresh-water shells were found ; marine shells 

 were discovered only in small quantities. Tlie Silurian forma- 

 tion of these districts may now be considered as proved beyond 

 doubt. 



The new ethnological museum opened at the H6tel des 

 Invalides, Paris, contains a collection of warriors belonging to 

 several nations and tribes, civilised and uricivilised. These models 



