i68 



NA TURE 



[June 12, 1890 



measurement of stellar distances, by MM. Loewy and Puiseux- 

 In previous communications, the authors have developed the 

 theory of the optical system formed by a double plane mirror 

 cut out of a single block of glass in the form of a prism, and 

 placed in front of the object-glass of an equatorial. The proper- 

 ties of the apparatus are now demonstrated, and a practical 

 method of observation deduced. — On the reduction of sulphates of 

 the alkalies by hydrogen and by carbon, by M. Berthelot. — The 

 author discusses in detail the mechanism of the reactions taking 

 place in these reductions, with especial reference to the condi- 

 tions obtaining during the process of manufacturing sodium 

 carbonate. The equation K2SO4 -F 4H2 = KgS + 4H2O ex- 

 presses approximately the final state of the system, but does not 

 at all represent the course of the reaction, which is probably as 

 follows : — 



(OKjSO^ -h 4H2 =r KHS -i- KOH -f sH^O ; 

 the KHS then decomposes. 



(2) 2KHS = KjS -t- HgS, 

 and the H2S reacts with the KOH. 



(3) KOH -1- H2S = KHS + H2O. 

 Equations (l) and (3) represent exothermic reactions, (2) is 



the expression of an endothermic dissociation which takes place 

 at the temperature of reduction. In addition to the above an 

 exothermic reaction takes place between the alkaline sulphide 

 and water vapour, thus — 



(4) K2S + H2O = KHS + KHO. 



The reduction by hydrogen takes place at a comparatively low 

 temperature. With respect to the action of carbon upon the 

 alkaline sulphates, it is shown that solid carbon even at a very 

 bright temperature fails to react with the sulphate, but that car- 

 bonic oxide at a bright red heat reduces the salt according to the 

 equation — 



(5) K2SO4 -f 4CO = KjS -f 4CO2, 



the reaction being markedly exothermic. — Note by M. Blan chard 

 accompanying the presentation of a work on the "Actions of 

 the Products secreted by Pathogenous Microbes." — On the 

 fossil Hippopotami of Algeria, by M. A. Pomel. The genus 

 Hippopotamus has been represented in Algeria at different times 

 during the Quaternary period, and the author describes the 

 order in which the types succeeded each other. Of four species, 

 two are said to be certainly special, and probably also a third, 

 whilst the last is almost unknown. — Observations of Brooks's 

 comet {a 1890) made with the Brunner equatorial at Toulouse 

 Observatory, by M. E. Cosserat. Observations of the posi- 

 tion of the comet, extending from April 28 to May 14, are 

 given. — On the curve representing diffraction phenomena, 

 by M. Ernest Cesaro. — On the characteristic equation of nitro- 

 gen, by M. Ch. Antoine. Some experiments by M. Amagat 

 on the compression of nitrogen between 39"5 and 42i'i atmo- 

 spheres are used to calculate the value of -^ -, where / is 



D(^ + t) 

 the pressure, and v the volume of a gas. Taking D = 2*830 

 -t- o'ooigi/^*^, which, however, can only be taken as a first 

 approximation, the mean value found is 3'io. — On the ballistic 

 electrometer, byM. Gouy. — The month of May 1890 at the Ob- 

 servatory of the Pare de Saint-Maur ; the cold of June i, by 

 M. E. Renou. The month of May was remarkable for low mean 

 pressure, viz. 753 mm. at an altitude of 49 '38 m. The mean 

 temperature was 14° "o, or o°7 above the average of other years. 

 On June i the minimum thermometer 2 metres above the ground 

 registered 2° "7, and the ground thermometer registered 3° "3 

 below zero at sunset.— On the determination of the molecular 

 weight at the critical point, by M. Philippe A. Guye. M being 

 the molecular weight of any body, k the critical coefficient (the 

 relation of the absolute critical temperature to the critical pres- 

 sure), and R the specific refractive power, given by the formula 



of Lorentz and Lorenz, we have M = i-8 i^ . The author 



shows the agreement of the results obtained by calculation 

 with those experimentally determined, and claims that his 

 method should rank with the vapour-density and cryosco- 

 pic methods of determining molecular weights. — On the 

 chloro-salts of iridium, and the atomic weight of this element, 

 by M. A. Joly. The double chlorides of iridium and potas- 

 sium and iridium and ammonium are described, and from the 

 results of their analyses the atomic weight of Ir is found to 



NO. 1076, VOL. 42] 



be 19275 (H = I) ; Seubert's value is Ir — 192744,— On the 

 oxides of manganese obtained in the wet way ; second part — 

 manganous acid, by M. A. Gorgeu. — On some new double 

 iodides of bismuth and potassium, by M. Ch. Astre. There are 

 now five of these double iodides known — namely, (Bilg^j, KI ; 

 (Bil3)2, 2KI, 2H2O ; (Bil.,)2, 3KI, 2H2O ; (Bil3)2, 4KI ; and 

 (Bil3)2, 6KI ; of which the three latter are new, and form the 

 subject of the present paper. — On soda-alum, by M. E. Auge. 

 The properties of this body are incorrectly described in text- 

 books. The author contrasts the observed properties with the 

 properties attributed to the compound by most authors. — The 

 bouquet of fermented drinks, by M, Georges Jacquemin. — New 

 researches on the origin of omphalocephlaic monsters, and on 

 the primitive duality of the heart in the embryos of Vertebrata, 

 by M. Dareste. — On the arrangement of the collections of molluscs 

 at the Natural History Museum, by M. Edmond Perrier. — On 

 the development of blastodermic layers in Gephyriea tubicola 

 {Phoronis Sabatieri, nov. sp.), by M. Louis Roule. — On the 

 androgynous castration of the Muscari comostim, Mill. , by the 

 Usiilago Vaillantii, TuL, and some remarkable phenomena 

 accompanying the parasitic castration of the Euphorbia, by M. 

 Ant. Magnin. — On the seleolithic syenite of Montreal, and on 

 the endom'orphous and exomorphous contact modifications of this 

 rock, by M. A. Lacroix. — Action of soluble substances pro- 

 duced by microbes on inflammation, by MM. Charrin and 

 Gamaleia. 



BOOKS, PAMPHLETS, and SERIALS RECEIVED. 



Characteristics of Volcanoes : J. D. Dana (S. Low).— A Contribution to 

 the Natural History of Scarlatina : Dr. D. A Gresswell (Oxford, Clarendon 

 Press). — A Manual of Pharmaceutical Testing: B. S. Proctor (Office of the 

 Chemist and Dtriggist). — Aluminium, 2nd edition : J. W. Richards (S. 

 Low).— Die Gesetze und Elemente des Wissenschaftlichen Denkens, Erster 

 Band : Dr. G. Heymans (Leiden, van Doesburgh).— British Cage Birds, 

 Part 2 : R. L. Wa'lace (Gill).— The Canary Book, Part 2 : R. L. Wallace 

 (Gill). — Elementary Algebra, 2nd edition : C. Smith (Macmillan). — Induction 

 and Deduction: C. C. W. Nadens (Bickers). —The Phil jsophy of Clothing : 

 W. M. Williams (Laurie) —Madagascar ; or, Robert Drury's Journal : 

 edited by Captain Oliver (Unwin). — Blackie's Modern Cyclopedia, vol. 6 

 (Blackie). — Fifty Years of Science, 4th edition : Sir J. Lubbock (Macmillan). 

 — Sanity and Insanity: C. Mercier (Scott). — Nature and Woodcraft: J. 

 Watson (Smith and Innes). — Den Norske Nordhavs-Expedition 1876-78, 

 xix. Zoologi— Actinida : D. C. Danielssen (Christiania, Grondahl).— Ob- 

 servations of the New England Meteorological Society in the year 1888 

 (Cambridge, Mass., Wheeler). — Meteorological Observations made at the 

 Summit of Pike's Peak, Colorado, January 1874 to June 1888 (Cambridge, 

 Mass., Wheeler). 



CONTENTS. PAGE 



Electric versus Gas Lighting 145 



A Text-book of Geology, By G. C 146 



Our Book Shelf:— 



Harrison and White : " Magnetism and Electricity " . 147 



Bower: " Science applied to Work " 147 



Letters to the Editor : — 



Testing for Colour-Blindness. — Latimer Clark, 



F.R.S 147 



Coral Reefs— Snail Burrows.— Prof. T. G. Bonney, 



F.R.S 147 



Coral Reefs, Fossil and Recent. — Dr. R. von Lenden- 



feld 148 



Photographs of Water Drops. — P. Lenard .... 148 



Climates of Past Ages. I. By Dr. M. Neumayr . 148 

 Lightning and the Electric Spark. {Illustrated.) By 



Shelford Bidwell, F.R.S.' 151 



Sports. By Dr. Maxwell T. Masters, F.R.S. ... 154 



A New Scientific Serial. By G. B. H 157 



Notes 158 



Our Astronomical Column : — 



Objects for the Spectroscope. — A. Fowler 161 



The Spectrum of Comet Brooks {a 1890).— A. Fowler 162 



The Planet Uranus 162 



Mr. Tebbutt's Observatory 162 



New Asteroid 162 



Coral Reefs and other Carbonate of Lime Forma- 

 tions in Modern Seas. By Dr. John Murray and 



Robert Irvine 162 



University and Educational Intelligence 166 



Societies and Academies 167 



Books, Pamphlets, and Serials Received 168 



