144 



NA TURE 



[June 8, 189; 



The commonly accepted version ofCarnol's method is therefore 

 an injustice to the celebrated author of "The Motive Power of 

 Heat." 



Paris. 



Academy of Sciences, May 29. — M. de Lacaze-Duthiers in 

 the chair. — Studies on diffraction gratings ; focal anomalies, by 

 M. A. Cornu. Gratings, although trustworthy enough to be 

 used for determining wave-lengths of light, yet present various 

 anomalies which might cast some doubt upon the rigour of the 

 optical principles upon which their construction is based. In 

 order to study these perturbations in detail and to eliminate 

 the attendant errors, M. Cornu constructed a machine for the 

 automatic ruling of lines spaced according to fixed laws, so as 

 to produce and exaggerate at will the anomalies whose origin 

 was to be verified. Thus the systematic error in the position 

 of the focus of spectrum images was reduced to two distinct 

 and purely geometrical causes : In plane gratings, to the exist- 

 ence of a feeble curvature of the ruled surface ; in a plain or 

 curved grating, to the existence of a regular variation in the 

 distance apart of the lines. In most cases these two causes co- 

 exist, which makes the laws of the optical phenomenon highly 

 complex. — On the volatilisation of silica and zirconia, and the 

 reduction of these compounds by carbon, by M. Henri Moissan 

 (see Notes). — Preparation in the electric furnace of some re- 

 fractory metals : tungsten, molybdenum, vanadium, by M. 

 Henri Moissan (see Notes). — On the preparation of zirconium 

 and thorium, by M. L. Troost. An intimate mixture of zir- 

 conia and finely comminuted sugar charcoal, the former being 

 in excess, is strongly compressed into small discs and placed in 

 a carbon retort. It is then subjected to the action of the 

 voltaic arc supplied by a current of 35 amperes and 70 volts, 

 the retort being placed in a closed chamber traversed by a slow 

 current of carbonic acid, so as to prevent the air from burning 

 and retransforming the metal into zirconia. The reduction is 

 immediate, and gives rise to small metallic masses which are 

 not pure zirconium, but a true carburet of zirconium, correspond- 

 ing to the formula ZrC^. If the carbon retort is lined with 

 zirconia the ingot is gradually freed from carbon, and leaves the 

 pure metal behind. This has a steel-grey colour and is ex- 

 tremely hard. It scratches glass deeply, and is untouched by 

 the best files. In air it is unaltered at ordinary temperatures. 

 At a red heat it oxidises at the surface if containing little carbon, 

 but burns brightly if containing much. It is not attacked by 

 acids except by hydrofluoric acid, which acts evea if greatly 

 diluted. Thorium is prepared in an exactly similar way from 

 the chloride. The reduction takes place more readily, giving 

 rise to a carburet, ThCj. The metal is very brittle, and less 

 hard than zirconium. It decomposes water in the cold, evolving 

 hydrogen and a hydrocarbon of pungent odour. In contact 

 with air it gradually swells up and forms a powder which burns 

 with greater rapidity and brightness than zirconium.— Observa- 

 tions on the volatilisation of silica, (>/™/o/ of M. Moissan's 

 communication. — On the phenacite of Saint-Christophe en 

 Oisans, by MM. A. Des Cloizeaux and A. Lacroix. — On 

 ordinary differential equations which possess fundamental systems 

 of integrals, by M. Sophus Lie. — The total solar eclipse ob- 

 served at Fundium (Senegal) on April 16, 1893, by M. N. 

 Coculesco. — On geometrical properties which only depend upon 

 spherical representation, by M. C. Guichard. — On surfaces 

 with lines of curvature plane in both systems and isothermals, 

 by M. Th. Caronnet. — Theorems relating to analytical func- 

 tions of « dimensions, by M. G. Scheffers. — On a general 

 property of fields admitting of a potential, by M. Vaschy. — On 

 the densities of some gases and the composition of water, by 

 M. .A.. Leduc. — On the rigidity of liquids, by M. J. Colin. — 

 Action of acetic anhydride upon linalol ; transformation into 

 geraniol, by M. G. Bouchardat. — A general method for the 

 analysis of butters, by M. Raoul Brullc. — On the physiology of 

 the crayfish, by M. L. Cuenot. — Mechanism of the hyperplasic 

 process in epithelial tumours ; applications, by M. Fabre- 

 Domergue. — Researches on the modifications of the excretion 

 of urea in the course of certain surgical maladies, and especially 

 after great operations ; consequences from the point of view of 

 therapeutics and treatment after operations, by M. Just Cham- 

 pionniere. 



Berlin. 



Physical Society, May 12. — Presidents, at first Prof. 

 Kundt, and later Prof, du Bois Reymond.— Dr. E. Pring- 

 sheim gave an account of his further researches on the 



NO. 1232. VOL. 48] 



cause of the emission of light by heated gases. By the method 

 already employed for sodium (see Nature, vol. xlv., p. 312) 

 he had recently tested the vapours of lithium, thallium, and 

 potassium. At the highest temperature, at which nickel was 

 fused, the vapours of these metals similarly gave an emission- 

 spectrum following on the absorption spectrum as long as 

 reduction processes were excluded. They at once showed their 

 characteristic spectral lines as soon as the salt used, or the 

 silicate formed from the metal in contact with the surface of the 

 porcelain tube, was reduced either by hydrogen, by the metal 

 itself, or by iron. The experiment of Dewar and Liveing, in 

 which, by heating lithium with potassium and sodium in an 

 atmosphere of hydrogen in an iron tube, they obtained the 

 lithium-line, was explained by the speaker as due to the above- 

 named cause, viz., a compound is formed of iron and lithium, 

 which is then reduced and exhibits both emission and absorption. 

 Dr. Pringsheim concluded from his experiments in support of 

 his views that the four elements — lithium, sodium, thallium, 

 and potassium— are not luminous when simply heated above 

 the temperature of the flame in which they ordinarily exhibit 

 their characteristic spectra. He believed rather that they only 

 show emission and absorption spectra when they are in the 

 nascent state resulting from processes of chemical reduction. 



BOOKS, PAMPHLETS, and SERIALS RECEIVED. 



Books. — A Treatise on Elementary Dynamics, 2nd edition : S. L. Loney 

 (Cambridge University Press). — An Introduction to Practical Bacte-iolngy: 

 Dr. W. Migula, translated by M. Campbell (Sonnenschein).— Some Hints 

 on Learning to Draw : G. W. C. Hutchinson (Macmillan). — The Hawks 

 and Owls of the United States in their Relation to Agriculture (Washington)^ 

 — The Geological and Natural History Survey of Minnesota, 20th Annual 

 Report (IVIinn.). — Missouri Botanical Garden, Fourth Annual Repnrt (St. 

 Louis. Mo.). — Modern Microscopy ; M. L Cross and M. J. Cole (Baillicre). 

 — Geological and Solar Climates : M. Manson (Dulau). — British Forest 

 Trees: J. Nisbet (Macmillan). — Darwin and Hegel: D. G. Ritchie (Son- 

 nenschein).— Lectures on Sanitary Law: A. W. Blyth (Macmillan). — Frag- 

 ments of Earth Lore : Prof. J. Geikie (Edinburgh, Bartholomew).— The 

 Lepicloptera of the British Islands, vol. i. Rhopalocera : C. J. Barrett (L. 

 Reeve).— Hypnotism, Mesmerism, and the New Witchcraft: E. Hart 

 (Smith, Elder). 



Pamphlets. — Die Klimate der Geologlschen Vergangenheit : E. Dubois 

 (Nijmegen, T'hieme). — Notes on the Gasteropoda of the Trenton Limestone 

 of Manitolsa, with a Description of One New Species; J. F. Whileaves. — 

 Sulla Dissipaiione di Energia in un Campo Klletrico Rotante e Sulla 

 Isteresi Elettrostatica : R. Ami) (Roma). 



Seriaf.s. — Brain, Parts 61 and 62 (Macmillan). — Engineering M:igaziiie, 

 June (New York). 



CONTENTS. PAGE 



The Royal Society Election. By W. T. Thiseltori- 



Dyer, C.M.G.,F.R.S 121 



Vertebrates of Argyll and the Inner Hebrides ... 123 

 Our Book Shelf:— 



Bryden : " Gun and Camera in Southern Africa " . . 125 

 Letters to the Editor : — 



Mr. H. O. Forbes's Discoveries in the Chatham 



Islands. — Henry O. Forbes 126 



Fundamental Axioms of Dynamics. — Prof. Oliver 

 Lodge, F.R.S. ; Prof. A. W. Rucker, F.R.S. ; 



Prof. J. G. MacGregor 126 



The Word Eudiometer. — Philip J. Hartog .... 127 

 Singular Swarms of Flies. — Prof. F. Jeffrey Bell; 



Henry Cecil 127 



The Annual Visitation of the Greenwich Observa- 

 tory. By W. J. S. L . 127 



Rev. Charles Pritchard, D.D., F.R.S. By W. 



E. P 130 



Notes 131 



Our Astronomical Column : — 



The Total Solar Eclipse (April 1893) 13J 



Meteor Observations 135 



Washburn Observations 135 



Finlay's Comet (1886 VII.) 135 



Geographical Notes 135 



Seismology in Japan. By Prof. John Perry, F.R.S. . 136 

 On Light and other High Frequency Phenomena. 



By Nikola Tesla 136 



University and Educational Intelligence 140 



Scientific Serials 140 



Societies and Academies 141 



Books, Pamphlets, and Serials Received 144 



