March i6, 19 i6] 



NATURE 



/o 



but the ratios of the mobilities are practically the 

 same as when the stable state has been reached. 

 When the air is dried higher values are again found, 

 and in this case also the ratios of the mobilities have 

 the same values. 



Paris. 

 Academy of Sciences, February 2'i>. — M. Camille Jor- 

 dan in the chair. — The President announced the death 

 of Richard Dedekind, and gave a short account of his 

 contributions to mathematics. — Paul Appell : Certain 

 polygons the summits of which describe algebraic 

 cunes, and of which the sides envelop algebraic 

 cur\'es. — C. Guichard : Plane networks which, in an 

 infinitv of ways, may be considered as the orthogonal 

 I projection of the lines of curvature of a surface.- — 

 i MM. Tarazona and Marti : Observation of the eclipse 

 of the sun of February 3, 19 16, made at Valencia 

 (Spain). Only the first contact could be observed. — E. 

 \ Goursat : The class of certain differential expressions. 

 ' — T. H. Gronwall : Deformation in conformal repre- 

 ! sentation under restrictive conditions. — B. Jekhowsky : 

 The Bessel functions of several variables expressed by 

 I Bessel functions of one variable. — Gaston Julia : The 

 ' reduction of positive quadratic forms. — P. Alexandroff : 

 The power of measurable ensembles B. — Lucien 

 I Vallery : The stability of hypochlorites in very dilute 

 i solutions. Consequences from the point of view of 

 i their use for the sterilisation of water (javelisation). 

 j A study of solutions of hypochlorite containing from 

 j one to five parts per million of active chlorine. The 

 : velocity of decomposition is affected by the medium in 

 ! two ways, one purely catalytic, the other chemical, 

 ! depending upon the presence of substances capable of 

 j reacting with the molecule of the hypochlorite or with 

 I its decomposition products.— G. A. Le Roy : The de- 

 I tection of free chlorine in town water supplies. A 

 I disagreeable taste becomes perceptible when the 

 amount of active chlorine reaches 0-05 part per 

 I million, and chemical control for solutions of such 

 ; dilution presents difliculties. It is suggested, that the 

 I active chlorine be concentrated by partial freezing of 

 the water. Starting with 10 litres of water, and 

 freezing q-8 litres, the remaining liquid readily gives 

 j the iodide of starch reaction ; 00005 milligram of 

 ' active chlorine per litre can be detected. — Louis Gentil : 

 ! The structure of the Middle Atlas (Central Morocco). — 

 ; N. Arabn : Studies on the Tertiary formations of the 

 ! basin of the Sea of Marmpra. — M! Deprat : The exist- 

 I ence of a fold of Palaeozoic age between Yunnan and 

 Tonkin. 



Washington, D.C. 

 ! National Academy of Sciences, (Proceedings, No. 2, 

 ; vol. ii.). — J. A. Harris : Personal equation and steadi- 

 [ ness of judgment in the estimation of the number of 

 i objects in moderately large samples. While there is 

 i no certain differentiation among the experimenters in 

 ^ personal equation, they differ distinctly in steadiness 

 ; °^. judgment. The latter is conspicuous in contrast 

 j with the former in that it is unmistakably influenced 

 i by previous experience. — T. B. Johnson : Polvpeptide- 

 I hydantoins. The formulas for a large number of poly- 

 j peptide-hydantoins are set up. Some of these sub- 

 I stances have already been synthesised and methods for 

 synthesising others are being developed.— J. X. Rose : 

 Recent explorations in the cactus deserts of South 

 America. Large collections of cacti in South America 

 have been made, including manv species which have 

 never before been collected, and some which, though 

 collected, have been poorlv described or wronglv classi- 

 fied.— H. N. Russell : The albedo of the planets and 

 their satellites. A table is given of the values finally 

 derived for the albedo of the various planets and 

 satellites. The values are in agreement with the cur- 

 rent views of the constitution of the bodies. The 



NO. 2420, VOL. Q7I 



j value for the earth is intermediate between those of 

 ! cloudy and cloudless plants. — R. A. Millikan : Quantum 

 ■ relations in photo-electric phenomena. So far as e.x- 

 ! periment has thus far gone Einstein's equation seems 

 I to be an exact statement of the energies of emission 

 j of corpuscles under the influence of light waves. Thus 

 the correctness of the quantum theory and the reality 

 ' of Planck's h are corroborated. — J. H. Ellis : The 

 ' chemical activity of the ions of hydrochloric acid deter- 

 mined by electromotive force measurements. In this 

 I paper are presented accurate measurements of the 

 I electromotive force at 18, 25, and }^~^° of voltaic cells 

 I of the type H„ HCl, Hg,CL-rHg, with the acid- 

 concentration varying from 003-4-5 normal. From 

 ! the data are calculated the energy ettects attending the 

 reaction which takes place in such cells and those 

 attending the transfer of hydrochloric acid in aqueous 

 solution from one concentration to another. From 

 these results are then calculated the chemical activities 

 (or effective concentrations) of the ions of the acid. 

 These activities are shown to decrease with increasing 

 concentration much more rapidly than do the ion- 

 concentrations derived in -rthe usual way from 

 i the electrical conductance ratio. — E. G. Conklin : 

 Effects of centrifugal force on the polarity 

 of the eggs of Crepidula. It is difficult, but 

 not absolutely impossible, to change the polarity 

 of eggs and cleavage cells, and the persistence of 

 |X)larity and the restoration of dislocated parts to 

 ' normal condition is connected with a somewhat re- 

 sistent framework of protoplasmic strands. — D. L. 

 Webster : The emission quanta of characteristic X-rays. 

 ! To excite any characteristic radiation it is necessary to 

 \ use a potential above a critical value. The lines all 

 ! increase in the same ratio for any given increase of 

 potential. There is reason to believe that the char- 

 \ acteristic rays are always a result of excitation of 

 i higher-frequency oscillators. — T. W. Vaughan : The 

 i results of investigations of the ecology of the Floridian 

 and Bahaman shoal-water corals. The ability of 

 i corals to remove sediment from their sur- 

 i faces, their mechanism for catching food, their 

 carnivorous nature, their relation to light and 

 temperature, and so on, have been studied. — C. D. 

 Walcott : Cambrian trilobites. Data have been assem- 

 ' bled to aid in clearing up some of the problems of 

 ' formations of the Appalachian region by a careful 

 j comparison of portions of their contained faunas with 

 '' those of other localities. — G. E. Hale and F. Ellerman : 

 The minute structure of the solar atmosphere. The 

 minute structure of the quiescent solar atmosphere 

 resembles that of the photosphere. The results 

 apparently support the hypothesis that the solar atmo- 

 sphere consists of parallel columns of ascending and 

 expanding gases, but such questions as the dimensions 

 of the columns and the direction of motion and 

 velocitv are reserved for subsequent discussion. — 

 — R. W. Wood : Monochromatic photography of Jupiter 

 and Saturn. The variation of the appearance of 

 Saturn and Jupiter when photographed with light of 

 different wave-lengths suggests a mist or dust in the 

 planet's atmosphere which scatters the shorter wave- 

 lengths. 



BOOKS RECEIVED. 



Elements of Highway Engineering. By Prof. .A. H. 

 Blanchard. Pp. xii + 5i4. (Xew York: J. Wiley and 

 Sons., Inc.; London: Chapman and Hall, Ltd.) 

 125. 6d. net. 



Aircraft in War and Peace. By W. A. Robson. 

 Pp. xi + 176. (London: Macmillan and Co., Ltd.) 

 25. 6J. net. 



Individuality in Organisms. By C. M. Child. Pp. 



