November 9, 191 1] 



NATURE 



67 



thus be analysed into well-defined radiations widely 

 different in penetrating power, and may be said to give 

 a line spectrum in X-rays. The absorbability of the 

 fluorescent radiations is given by the following values of 

 X/p, where A is the coefficient of absorption of these radia- 

 tions in aluminium of density p : — 



Ag radiuor: (S>.rics K) [2'5] ; (S. ries L) 700 



Sb ,, ,, 1-21 ,, 435 



I ,, ,. o'92 ,, 300 



Ba ,, ,, Q-S ,, 224 



Paris. 

 I Academy of Sciences, October 30. — M. Armand Gautier in 

 the chair. — B. Baillaud : Presentation of two volumes of 

 jihe " Annales de I'Observatoire de Paris." — Ch. Andre: 

 jrhe formation of suns. , Referring to recent adverse 

 criticisms of Laplace's theory, the author maintains that 

 ■ecent physical researches confirm this theory. — A. 

 pemoulin : The R surfaces. — Eugenio Elia Levi : 

 Periodic differential equations. — Paul Dienes : The sum- 

 jTiation of Taylor's series.— Henry Hubert : The parabolic 

 orm of the exposed acid crystalline rocks in western 

 •\frica. The water erosion takes place only at the expense 

 jf granitic rocks, and is characteristic of certain regions, 

 fhe effect of the motion of the cutting particles is shown 

 jo result in a curved outline. — G. Millochau : Contribu- 

 ion to the study of the spectral effects of electric dis- 

 :harges in gases and vapours. The image from a vacuum 

 ube containing the gas under examination at a known 

 Pressure is projected on to a circular photographic film 

 Rotating at a high known velocity. Seven kinds of simple 

 lischarge are described, and three types of mixed dis- 

 harge. All the results are in accord with hypotheses 

 vhich connect the production of the spectrum with the 

 emperature of the molecule and the dissociation effects 

 corresponding with that temperature. — Albert Colson : The 

 heory of solutions and heats of solution. The author 

 egards the identification of the dissolved particle with the 

 hemical molecule as inadmissible, and considers that the 

 lissolved particle is generally polymolecular. He suggests 

 lissolecule as a distinctive name for the dissolved particle, 

 fhe difference between the heat of solution of a gas and 

 ts heat of condensation, which should be zero according 

 .0 the van 't Hoff hypothesis, represents the heat dis- 

 engaged by the molecular contraction giving rise to the 

 Jissolecule. — MM. Broniewski and Hackspill : The 

 lectrical properties of the alkali metals, of rhodium, and 

 ^f iridium. Measurements are given of the thermoelectric 

 ■ower of caesium, rubidium, potassium and sodium, and of 

 hodium and iridium. The purification of the alkali metals 

 /as effected by distillation in a vacuum. — G. D. 

 linrichs : The atomic weights of the dominant elements. 

 -E. Chablay : The use of liquid ammonia in chemical 

 ■eactions. Researches on the alcoholates. An alcohol 

 .issolved in liquid ammonia immediately decolorises a blue 

 plution of potassammonium or sodammonium, hydrogen, 

 .mmonia, and the anhydrous alcoholate RONa being formed. 

 u blue solution of calcium-ammonium reacts similarly, the 

 alcium alcoholate being formed. Barium and strontium 

 •mmoniums act similarly.— Maurice Lanfry : The oxy-)3- 

 .lethylthiophenes. — MM. Taffanel and Dautriche : The 

 iiode of firing explosives. In blasting in mines one 

 partridge containing fulminate is usually arranged to 

 xplode several cartridges containing safety explosive only, 

 .xporiments are described showing the most advantageous 

 rrangement of the fulminating cartridge with respect to 

 tie others. — Jean Friedel : The effect on vegetation of a 

 'lore complete darkness than that currently emploved in 

 jiboratories. A box for growing plants in the dark is 

 escribed in which the exclusion of light is so perfect that 

 j delicate photographic paper is unaffected after prolonged 

 .Kposure. The results on the plants are compared with 

 ' obtaining under ordinary conditions, in which the 



ion of light is not so perfect. — Pierre Berthault : The 

 lions of tuberiferous Solanum. — P. Desroche : The 

 fction of various light radiations on the motion of the 

 oospores of Chlamydomonas. — A. Marie and A. 

 onnadieu : Leucogenesis and intestinal epithelium. — A. 

 iag^nan : Human monsters. — Pierre QeorKevitch : The 

 i>rmation and germination of the spores of Bacillus 

 iiermophilus vragnensis.— Louis Qentil : The country of 



NO. 2193, VOL. 88] 



Zaer, western Morocco. — Maurice Lug^eon : The existence 

 of two phases of Palaeozoic foldings in the western Alps. 

 — Carl Renz : The extension of the Palaeozoic formations 

 in the islands off the coast of Argos. — Fernand Meunier : 

 The Blattidae of the Commentry Coal-measures. The lake 

 of Commentry would appear to have been inhabited by a 

 fauna of Blattidae, less rich than in the American deposits, 

 and represented by a very small number of genera, some 

 of which possessed extremely proHfic species. — Ch. Moureu 

 and A. Lepape : The rare gases in fire-damp. Analyses 

 of five specimens of fire-damp collected under conditions 

 excluding air. One striking fact brought out by these 

 analyses is the much higher proportion of helium to 

 nitrogen than that existing in air. The nitrogen from the 

 Mons specimen contained no less than 13 per cent, of 

 helium. 



BOOKS RECEIVED. 



Die Palaeobotanische Literatur. Bibliographische tJber- 

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Die Bearbeitung des Glases auf dem Blasetische. By 

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Psychology and Pedagogy of Writing : a R6sum6 of the 

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Mental Fatigue : a Comprehensive Exposition of the 

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Der Panamakanal. Die Bedeutung des Kanalbaues 

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Islands of Enchantment : Many-sided Melanesia Seen 

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Manual of Farm Animals : a Practical Guide to the 

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Sir John Burdon Sanderson : a Memoir by the late 

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Die Silicate in Chemischer und Technischer Beziehung. 

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Cours de la Faculty des Sciences de Paris. Lecons sur 

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Astronomy. By A. R. Hinks. Pp. 256. (London : 

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Introduction to Science. By Prof. J. A. Thomson. Pp. 

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Geometry for Schools. By W. G. Borchardt and the 

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