48 



NA TURE 



[Nov. lo, 1887 



phosphites of ammonia, by M. L. Amat. The process is described 

 by means of which the author has obtained the salt (PhOsHO) 

 NH^OjHO, which has not hitherto been studied. It may be 

 prepared very easily in beautiful crystals and in a perfectly pure 

 state, which is rarely the case with phosphites. — On the produc- 

 tion of the double carbonate of silver and potassium, by M. A. de 

 Schulten. The carbonate of silver obtained by the action of an 

 alkaline carbonate on the nitrate of silver is found to be sometimes 

 yellow, sometimes white, while in most cases the white precipitate 

 takes the yellow colour when washed with water. The experiments 

 here described show that, as anticipated by the author, the white 

 colour of the precipitates is due to a combination of the car- 

 bonate of silver with the alkaline carbonate, this combination 

 being transformed by the water into a yellow carbonate by 

 eliminating the alkaline carbonate.- — On some salts of aniline, 

 by M. A. Ditte. The salts here described are formed by 

 metallic acids almost insoluble in water, or by energetic oxidants, 

 and have been obtained by the process of double decomposition. 

 They comprise a molybdate, a tungstate, a vanadate, an iodate, 

 a chlorate, and a borate. — Formation of normal amylic alcohol 

 in the fermentation of glycerine set up by Bacillus butylicus, by 

 M. Ed. Charles Morin. Fitz has shown that, under certain 

 conditions of temperature and environment, this Bacillus trans- 

 forms glycerine into alcohols, glycol, and acids. To the normal 

 ethylic and propylic alcohols determined ia the products of the 

 fermentation must now be added normal amylic alcohol, which 

 may be easily extracted by distillation.— On a remarkable variety 

 of mineral wax, by MM. G. Dollfus and Stanislas Meunier. The 

 specimens here described came from Sloboda Rungorska, near 

 Kolomea, in Austrian Galicia, vv'here petroleum wells have 

 recently been sunk. A rough analysis yields H = 15, C = 85, 

 corresponding to the formula CH, with density o'6o. 



Berlin. 

 Physical Society, October 28. — Prof, von Helmholtz, Pre- 

 sident, in the chair. — The President gave a heart-felt address in 

 memory of the late Prof. Kirchhoif, who was Vice-President of 

 the Society. — Dr. Robert von Helmholtz showed and explained 

 before the Society the experiments on vapour currents, of which 

 he has recently given an account in IVeideniann' s Annalen. In 

 his earlier expenments on the formation of mist he arrived at 

 the same results that had been obtained by Aiiken — namely, that 

 the condensation of supersaturated aqueous vapour, as it fcn-nis a 

 mist, takes place only at some nucleus which is provided or- 

 dinarily by the particles of dust in the air. His observations on 

 vapour currents have, however, now shown that other conditions 

 have an influence on the condensation. When a platinum wire 

 heated red-hot by an electric current is brought near a current 

 of vapour, the colour of the latter changes owing to an increased 

 condensation, A similar result was obtained when the following 

 agents were employed instead of the red-hot platinum wire, viz. 

 the gases evolved from a hydrogen flame ; the gases which rise 

 from a glowing wire gauze; a metallic point from which elec- 

 tricity is making its exit ; an electric spark ; the vapours which 

 rise from sulphuric acid ; sal-ammoniac when formed in the current 

 of vapour by the interaction of hydrochloric acid gas and am- 

 monia. In all these last-named cases, where the condensation 

 is facilitated, it is impossible to speak of any ' ' nuclear " action. 

 The speaker was of opinion that a supersaturated vapour, just 

 as is the case with water cooled below its freezing-point, or 

 a supersaturated solution of any salt, can be made to 

 pass from its condition of unstable equilibrium by two 

 meaiis, either by some "nuclear" action or by a sudden 

 vibraLion. Mist formation is the result of a "nuclear" action 

 in iho e cases in which the atmospheric dust induces a 

 condensation in the supersaturated vapour. The condensation 

 must be regarded as the result of the sudden vibration in the 

 other cases uientioned above. Although in these cases no truly 

 mechanical vibration takes place, still the chemical processes 

 involved m the production of the gases evolved by the flame, in 

 the evaporation of the sulphuric acid, in the formation of the 

 sal-ammoniac, at the point from which the electricity is making 

 its exa, and m the electric spark, are to be regarded as sd many 

 sources ot molecular tremors which upset the unstable equilibrium 

 of me supersaturated vapour. — Dr. Dieterici gave an account of 

 his exijcrunents on the determination of the mechanical equiva- 

 lcn> 01 neat by the indirect electrical method. He made this 

 choice of method on account of the exactness with which elec- 

 trical values can now be determined in absolute units. The 

 speaker described the general arrangement of his experiments 

 and gave a detailed account of the ice calorimeter which he used, 



as specially modified by himself. As the result of his series of 

 measurements he obtained closely agreeing values for the 

 mechanical equivalent of heat, namely 424*4 and 424'2 as the 

 mean of each series, the highest and lowest values obtained 

 difiering but little from the mean of the determinations. When 

 making his calculations the speaker took as the specific heat of 

 water, the mean of the determinations made between 0° C. and 

 100° C. The statements which have been made respecting changes 

 in the specific heat of water as dependent on changes of tem- 

 perature differ so greatly with different observers that the mean 

 values based on their results provide no constant factor ; the 

 speaker's determinations would have been considerably different 

 had he taken as his basis any other value of the specific heat of 

 water. He next compared the results of his experiments with 

 those of earlier observers, and discussed the very marked differ- 

 ences in the valuco given for the specific heat of water at various 

 temperatures. He thinks that the specific heat of water may best 

 be determined by the electrical measurement of the mechanical 

 equivalent of heat, and intends to investigate this question more 

 fully at a later date. 



BOOKS, PAMPHLETS, and SERIALS RECEIVED. 



Pen and Pencil in Asia Minor : W. Cochran (Low). — An Elementary 

 Treatise on Light and Heat : Rev. F. W. Aveling (Relfe).— British and 

 Irish Salmonidse : F. Day (WilHams and Norgate). — Ff^a Expeditionens, 

 2 vols. : A.E. Nordenskjold(Beigers, Stockholm). — L'Atniosphere et Met^oro- 

 logie Populaire: C. Flammarion(Hachette, Paris). — Spezial Karte von Afrika, 

 2, 3, 4, 5 Lief. (Perthes, Gotha). — Guatemala ; the Land of the Quetzal : W. 

 T. Brigham (Unwin).— The Microscope in Theory and Practice, translated 

 from the German of Prof. Carl Naegeli and Prof. S. Schwendener (Sonnens- 

 chein). — Reynolds's Experimental Chemistry, Part 4, Organic (Longmans). — 

 Klima und Gestaltung der Erdoberflache : Dr. J. Probst (Schweizerbart'sche, 

 Stuttgart). — Beitrage zur Geophysik, i. Band : Prof. Dr. Georg Gerland 

 (Schweizerbart'sche, Stuttgart). — Die Japanischen Seeigel, 1 Theil : Dr. L. 

 Diiderlein (Schweizerbart'sche, Stuttgart) — The Lake Age in Ohio : E. W. 

 Claypole (Maclachlan and Stewart). — Gold-fields of Victoria, Reports of the 

 Mining Registrars for Quarter ended June 30, 1887 (Melbourne). — Report on 

 the Progress and Condition of the Government Botanical Gardens at 

 Saharanpur and Mussoorie for Year ending March 31, 1887 (Allahabad). — 

 Coleoptera ; or, Beetles of South Australia :_ J. G. O. Tepper (Wigg, 

 Adelaide). — ^The Answer to the Universal Question, What is an Earthquake? 

 — Journal of Anatomy and Physiology, October (Williams and Norgate). — 

 Journal of the National Fish-Culture Association, October. — Journal of the 

 Chemical Society, November (Gurney and Jackson). 



CONTENTS. PAGE 



A Conspiracy of Silence. By Prof. T. G. Bonney, 



F.R.S 25 



A Text-book of Algebra 27 



Practical Botany 28 



Our Book Shelf :— 



Flight: " A Chapter in the History of Meteorites " . 30 



Bale: " A Hand-book for Steam Users " 30 



" The Encyclopaedic Dictionary " 30 



Mrs. Fitzgerald: "A Treatise on the Principle of 



Sufficient Reason " 30 



Letters to the Editor : — 



" Infusorial Earth." — T. V. Lister 30 



The Electrical Condition of the Peak of Teneriife. — 



Hon. Ralph Abercromby 31 



"Toeing" and "Heeling" at Golf. {Illustrated). — 



T. Mellard Reade 31 



The Ffynnon Beuno and Cae Gwyn Caves. — G. H. 



Morton 32 



The Victoria University 32 



Thermo-magnetic Machines 33 



Notes 33 



Our Astronomical Column : — 



The Variable Star U Ophiuchi 36 



The New Algol-Variable, Y Cygni 37 



Olbers' Comet, 1887 37 



Astronomical Phenomena for the Week 1887 



November 13-19 y] 



Geographical Notes 37 



Meteorological Notes 38 



The Work of the International Congress of Geologists. 



II. By G. K. Gilbert 40 



Technical Education. {Illustrated.) By Prof. Hele 



Shaw • .... 43 



Scientific Serials 47 



Societies and Academies 47 



Books, Pamphlets, and Serials Received 48 



