426 



NATURE 



[November 25, 1920 



effect. The appearance of tfie mirage was subject to 

 variations wfiich were dependent upon such factors 

 as the contour of the ground, the height of the 

 observer, and the altitude of the sun. 



Paris. 

 Academy of Scieacei, November 2. — M. Henri 

 Deslandres in the chair. — .M. <ie Sparre : The ram- 

 stroke in pipes feeding turbines with strong reaction. 

 The ordinary formula giving the pressure in a water- 

 main set up by a sudden stoppage of the motion of 

 the water cannot be applied without serious error to 

 mains supplying turbines with a strong reaction. The 

 necessary moditications of the formula are given. — 

 G. Clamician and C. Ravenna : The biological signi- 

 fication of alkaloids in plants. .Alkaloids have been 

 regarded as refuse products which the plant is un- 

 able to eliminate. From an experimental study of 

 the action of various alkaloids and substances related 

 to them on young bean plants it is shown that this 

 view cannot be sustained. — M. Gevrey : The resolu- 

 tion of problems at the limits relating to equations of 

 the second order of elliptical and parabolic types. — 

 B. Uambier : Couples of two minimum surfaces cor- 

 responding as focals of a rectilinear congruence, with 

 conservation of the asymptotic lines and the lines of 

 zero length. — .M. Risser : An application of Volterra's 

 equation to the problem of distribution by age. — MM. 

 Claude and Driencourt : A new type of prism astrolabe. 

 A description and photograph of the new instrument 

 are given. Compared with the older type, it is less 

 than half the weight and easier to set up and 

 adjust. — M. Holweck : Experimental researches on 

 X-rays of great wave-length. In the apparatus 

 described ionising rays were produced for a difference 

 of 70 volts between the anode and cathode ; this 

 would correspond to a wave-length of about one-sixth 

 of .Schumann's ultra-violet. "Determinations were 

 made of the coefficient of absorption of the soft X-rays 

 in different gases. — J. Cabannes : Measurement of the 

 luminous intensity diffused by argon. New deter- 

 mination of .\vogadro's constant. The value found 

 by this method is 6-9x10", in good agreement with 

 the well-known values of Millikan (6-07x10") and 

 Jean Perrin (6-85x10"). — MM. Chauvenet, P. Job, and 

 G. Urbain : The thermochemical analysis of solutions. 

 Equimolecular solutions of various salts are mixed in 

 varying proportions, the volume being kept constant. 

 The heat evolved on mixing is measured, taking 

 account of the specific heats of the solutions. Curves 

 are given illustrating the application of this method to 

 the svstems potassium iodide-cadmium iodide, copper 

 chloride-aluminium chloride, and copper chloride- 

 magnesium chloride. The formation of the complex 

 salts. KXdI., (2CuCl„-^MgCl,), (sCuCl^aMgCL), 

 (CuCL,2.\lCl,,), and f2CuCL,AlCl,,), was clearlv indi- 

 cated bv this method. — P. Loisel : The variations of 

 the radio-activitv of the springs of Bagnoles-de-l'Orne 

 and their relation to the rainfall. — M. Chopin : An 

 automatic indicator of the amount of moisture in 

 cereals.— J. de Lapparent : Crystals of felspar and 

 quartz in the limestones of the Middle Trias of Alsace 

 and Lorraine. — G. Depape : The presence of Juglans 

 cinerea fossilis in the Plaisanrian flora of Saint- 

 Marcel-d'Ardeche. — J. Touch : The diurnal variation 

 of temperature in the .Antarctic. — .A. Lumiere : The 

 awakening of the soil. The activitv in the soil, with 

 rapid grermination of seeds, which takes place in the 

 snring, was at one time supposed to be caused bv rise 

 of temperature : this, however, was disproved bv 

 Miintz and Gaudechon, who showed that a maximum 

 of microbial activitv was produced indeoendent of the 

 temperature. Their sugtjestion that this recurrence 

 of activity was to be ascribed to a predilection of the 



NO. 2665, VOL. 106] 



micro-organisms for a given period of the year, 

 atavism, the author regards as unsatisfactory, and 

 he now suggests another p>ossible cause, the exist- 

 ence in the soil of toxic products secreted by the roots 

 of plants or resulting from the transformation of 

 vegetable debris after the fall of leaves and the death 

 of annual plants. Experiments in support of this 

 view are described. Soil collected in November was 

 thoroughly washed to remove soluble toxic products, 

 and at the temperature of the laboratory this soil 

 produced vegetation with great rapidity. The same 

 soil unwashed was sterile as regards growth. The 

 washings, concentrated, were proved to prevent 

 growth. — F. Vincens : .Abnormal ligneous formations 

 in the bark of Hevea hrasiliensis. — J. Dulrenoy : The 

 experimental bacterial tumours of Epicea. — J. Delphy : 

 The reproduction of mudworms : fecundation, seg- 

 mentation, and morphogenesis. — M. Nicolle and E. 

 Cesari : The effects and constitution of the antibodies. 



Naples. 

 R. Accademia delle Scienze fisiche e matematiche, 



May 3. — Prof. Monticelli, president, in the chair. — 

 F. Tricomi': Series of functions of lines. 



May 8. — Prof. Montesano, vice-president, in the 

 chair. — ¥. Amodeo : Researches of a Neapolitan 

 eighteenth-centurv mathematician on certain theorems 

 of -Archimedes. Nicolo de Martino (born at Faicchio 

 in 1701, died at Naples in 1769) rediscovered and 

 proved by new and original methtxis several theorems 

 in mensuration contained in the lost manuscripts of 

 .Archimedes. These, which w-ere published in 1768 in 

 a text-book on solid geometry and conic sections 

 intended for .Armv cadets, show De Martino to have 

 been a mathematician of great power. 



June 7. — Prof. Monticelli, president, in the chair. — 

 C. Colamonico : A zone of carso known as " vurgo " in 

 the Bari territory. This forms part of a series of 

 researches bv the author on the carso of southern 

 Italv. The present zone occurs in a little-known dis- 

 trict of .Apulia. — M. Pascal: N'ple integrals in the 

 complex field. 



Tune 12. — M. Pascal : Multiple integral of a 

 differential form. 



June 19. — F. Tricomi : Series of powers in the field 

 of functions of lines, ii. 



Cape Town. 



Royal Society of South Africa, September 29. — Dr. 

 J. D. F. Gilchrist, president, in the chair. — J. R. 

 Sutton : A possible lunar influence upon the velocity 

 of the wind at Kimberley. IV. The object of this part 

 of the discussion is to determine whether there are any 

 points of agreement between the air tides and the 

 lunar wind period sufficientlv definite to form the 

 nucleus of a theorv which could be used to explain 

 the comparatively great air speeds found in previous 

 papers and attributable to the moon. For this 

 purpo.se the air tides at perigee and at apogee 

 have been determined (bv .Sabine's method) for the 

 ten years 1897-1906 and compared with the wind 

 movements. A diagram is given showing how the 

 air pressures and wind movements compare one w'ith 

 the other. Both agree in the main, though with 

 certain important exceptions confirming previous con- 

 clusions that the lunar influence upon the velocity 

 of the wind cannot be exerted in a verv simple way 

 through the medium of the air tides. — J. P. Dalton : 

 The integrated velocity equations of chemical re- 

 actions. The object of the note is to show how the 

 integrals of manv velocitv equations which occur in 

 practice mav be written down in terms of a certain 

 function of the relative initial concentrations of the 

 reactants and of its derivatives. — C. Piiper : Medical 

 folk-lore of the .Abantu in the Lijdenburg district. 



