June 13, 1907] 



NA TURE 



167 



this purpose the deviation of the rays in an electrostatic 

 fiekl was observed and compared with that of the 3 rays 

 from uranium. The conclusion reached in the earlier 

 paper is confirmed, that the potassium rays are rays 

 the average velocity of which is less than that of the 

 6 rays of uranium. Incidentally, convincing proof was 

 obtained of the photographic action of the rays. It seems 

 beyond doubt that potassium must be classed among the 

 radio-active elements. — The number of electrons in an 

 atom : N. R. Campbell. A somewhat speculative calcu- 

 lation of the number of electrons in a radio-active atom 

 based on the energy liberated in radio-active processes. 

 The estimation of the average energy of an intra-atomic 

 electron is based on observations of the velocity of the 

 slo\v 5 rays from radium. The conclusion is reached that 

 the number of electrons is probably of the same order of 

 magnitude as that deduced on the assumption that the 

 whole mass of an atom is the sum of the masses of the 

 contained electrons. General arguments are offered for 

 the view that the number of electrons in a radium atom 

 cannot be less than 1300, and is probably very much 

 greater. — The longitudinal impact of metal rods with 

 rounded ends : J. E. Sears. The paper deals with the 

 determination of the velocity of propagation of elastic 

 waves in metal rods by means of observations on the 

 duration of their longitudinal impact. The experiments 

 were carried out with rods of steel, copper, and aluminium, 

 and in every case the observed value of the wave-velocity 

 was within \ per cent, of that calculated from static 

 tests bv the formula v= -/Eg/p, with the proper correction 

 for adiabatic propagation. It was also observed that, for 

 the exceedingly short times involved in these experiments, 

 stresses far exceeding the elastic limit of the material can 

 be applied without producing any permanent effects. — 

 Selective absorption of Rontgen rays : G. W. C. Kaye. 

 A Rontgen-ray bulb was constructed so that a pencil of 

 kathode rays fell on an antikathode which was one of a 

 batch of metals mounted on a small carriage which could 

 be moved along inside the tube by a magnet from out- 

 side. The quantity of Rontgen rays passing through a 

 thin aluminium window in the tube was measured by their 

 ionising effect. Absorbing screens of different metals were 

 placed in turn between the ionisation chamber and the 

 aluminium window. Using a plate of aluminium as the 

 absorber, the relation between the amount of transmitted 

 radiation and the atomic weight of the metal used as anti- 

 kathode was found to be approximately a linear one over 

 a wide range of atomic weights. Screens of a few other 

 metals were employed, and the results indicate that a 

 metal is specially transparent to the Rontgen radiation 

 from an antikathode of that metal, and that this abnormal 

 transparency is shared in less degree by metals of atomic 

 weight differing little from that of the antikathode. The 

 effect seems to indicate that the Rontgen rays emerging 

 from the interior of the antikathode to the surface undergo 

 selective absorption, leaving the remainder specially 

 penetrating to further layers of the same substance. — The 

 transmission of earthquakes through the earth (second 

 paper) : Rev. O. Fisher. — Note on the influence of 

 extraneous forces upon the proportion of the se.xes pro- 

 duced by canaries : W. Heape. The breeding results in 

 two aviaries are examined. In the one (N), the young 

 nroduced were in the proportion of 76-99 cocks per 100 

 hens ; in the other (G), 353-3 cocks per 100 hens were bred. 

 This remarkable difference in the proportion of the sexes 

 produced in these tw^o aviaries is shown to be consistent 

 both in detail and in the total results. Moreover, it is 

 shown that a pair of N's birds transferred to G's aviary 

 produced a large excess of cocks, and a pair of G's 

 birds bred in N's aviary produced young of which the 

 sexes were closely in accord with the average proportion 

 obtained in the aviary that year. Examination of details 

 regarding the food supplied and the temperature and 

 surroundings to which the birds were subjected in these 

 two aviaries indicates the probability that these factors 

 exerted selective action on the generative elements dehisced 

 by the parent birds, and may be interpreted as evidence of 

 the exercise of extraneous forces on the proportion of the 

 sexes produced. 



NO. 1963, VOL. 76] 



P.ii;is. 

 Academy of Sciences, June ^.— M. Henri Becquerel in 

 the chair. — The origin of ihi- irregularities of the lunar 

 surface : MIVI. Lcewy and '/>uiseux. A critical discussion 

 of the theories of Laplace and G. H. Darwin concerning 

 the moon's origin, and the present condition of its surface. 

 — Selenium hexafluoridc : Sir \V. Ramsay. A reply to 

 the criticisms of M. Lebeau on the selenium hexa- 

 fluoride discovered by Prideaux. — Magnetic observations at 

 Tananarive : Ed. El. Colin. The results are summarised 

 in three tables showing the absolute measurements of 

 declination, inclination, and the horizontal component 

 from May, 1900, to .'\pril, 1907. — Tetramelhyl-dioxy- 

 acetone : Louis Henry. .An account of the study of the 

 reaction between mesoxalic ester and magnesium methyl 

 bromide by M. Joseph Lemaire. The magnesium com- 

 pound being used in excess, the pentamethvl derivative 

 (CHJ,.C(OH).C(CH,)(OH).C(OH)(CH,), was' looked for. 

 The actual product, however, proved to be 



(CHj3.C{OH).CO.C(OH)(CH3),, 



the physical properties of which are given. — Some appli- 

 cations of the theorem of Landau-Picard : C. Caratheo- 

 dory. — Integral invariants : E. Goursat. — .\n apparatus 

 for the study of telephonic currents : Henri Abraham and 

 M. Devaux-Charbonnel. The essential part of the 

 apparatus is the moving coil galvanometer for alternating 

 currents described by H. Abraham in an earlier paper. 

 This can be arranged so as to measure, not only the ampli- 

 tudes, but also the phases and strength of telephone 

 currents. — The speaking condenser : Pierre Seve. — A self- 

 recording pyrometer with fixed photographic plate : M. 

 Wologrdine. The time ordinate is obtained by a mirror 

 rotating round a horizontal axis at a uniform rate. — An 

 apparatus for the preparation of a constant stream of 

 pure oxygen : Gustave D. Hinriclis. The centre bulb of a 

 Kipp is filled with well-washed granular pyrolusite, the 

 liquid consisting of hydrogen peroxide acidified with one- 

 twelfth of its volume of concentrated .sulphuric acid. — The 

 action of silicon tetrachloride on silver and copper : Em. 

 Vigrouroux. With silver, the tetrachloride is partially re- 

 duced to the sesquichloride ; the silver not converted into 

 chloride is free from silicon. With copper, the metallic 

 ingot remaining contains about 2-4 per cent, of silicon. — 

 The transformation of the esters of the o-bromo-fatty 

 acids into the corresponding a-iodo-compounds : F. 

 Bodroux and F. Taboury. The a-bromo-ester is treated 

 with anhydrous magnesium iodide in presence of ether. 

 The reaction is energetic and practically quantitative. — 

 A new method of synthesis of biprimary compounds con- 

 taining an odd number of atoms of carbon : dimethoxy- 

 heptane, 1.7 CH,0(CH,),O.CH., : J. Hamonet.— The 

 synthesis of the auramines by means of the oxalic esters : 

 ."i. Guyot. — The action of organo-magnesium compounds 

 on the cyclic alkylidene ketones : Henri de Beville.— .A 

 new type of bisazoic compound : H. Duval. — .\n alkaline 

 microgranite collected at (Irahani's Land by Dr. Charcot's 

 .Antarctic Expedition : E. Gourdon. — The dehiscence cf 

 some stamens : M. Pauchet. — The rdlc of comparative 

 anatomy in the distinction between the species of the genus 

 Cistus : M. Gard. — .A new method of separating and 

 estimating the organic acids in fruits and vegetables : 

 J. M. Albahary. — The cultural mutation of Solatium 

 tuberosum : Edouard Meckel. — The xylophage parasites of 

 Manihot Glaziovi : P. Lcsne.— The structure of the spinal 

 medulla : N. A. Barbieri.— Fluorine in the shells of non- 

 marine molluscs : P. Carles. Fluorine was found in all 

 the non-marine molluscs examined, but in quantities much 

 smaller than in the shells of marine molluscs.— The in- 

 fluence of the rapid displacements of air caused by the 

 motor-car on the general nutrition : A. Mouneyrat. Both 

 in normal and anfemic persons the number of red corpuscles 

 in the blood is increa.sed by moderate use of the motor- 

 car. In neurasthenia accompanied by insomnia there is 

 also a marked improvement. — .A new method for the ex- 

 perimental diagnosis of tuberculosis: H. _ Vallee. Von 

 Pirket has recently proposed the lesions arising from the 

 aoplication of a dilute solution of tuberculin to the skin 

 of tuberculous subjects as a means for diagnosing tubercu- 



