April 22, 1909J 



NA TURE 



239 



will possess only sufticient energy to permit it to travel 

 a fraction of a millimetre before being stopped by collision 

 with air molecules. On the other hand, at very low 

 pressures, these particles should travel considerable 

 distances without being stopped by the rarefied air, and 

 come lo rest on the enclosure containing the emanation. 

 The case is similar for the formation of radium B from 

 radium A. To investigate these phenomena, discs were 

 suspended, in vacuo, above surfaces rendered active by the 

 various disintegration products of radium, and the activity 

 obtained on the discs after exposure was measured in the 

 normal manner by a quadrant electrometer. The principal 

 results obtained in this paper may be summarised as 

 follows : — (1) When radium emanation, in radio-active 

 equilibrium with its products of disintegration, is con- 

 densed at the bottom of an evacuated tube immersed in 

 liquid air, active deposit particles are radiated up the 

 tube. This phenomenon is ascribed to the recoil of the 

 residual atom when an a particle is emitted. (2) The law 

 of absorption of this radiation, both in air and hydrogen, 

 has been investigated. The radiation reaching a surface 

 at a fixed distance from the condensed emanation is an 

 exponential function of the gas pressure. (3) From the 

 rate of decay of the activity collected on a surface ex- 

 posed to the radiation from the emanation, it appears 

 that both radium A and radium B reach the surface. 

 (4) Radium B and radium C are both radiated through a 

 vacuum from a surface previously rendered active by 

 exposure to the emanation. Supposing that radium B 

 emits only 18 particles, the radiation of radium C must 

 be due to the recoil of the atoms when particles are 

 emitted. — Spliaerostoma ovale, n. gen., and Crossotheca 

 Grievii, n. spec, an account of the structure and relations 

 of the reproductive organs of Heterangium Grievii : Dr. 

 Margaret Benson. Sphacrostoma ovale {Conostoma ovale 

 et intermedium. Williamson) is the earliest Paleozoic ovule 

 so far known structurally. It is a small ovule 3-5 mm. 

 in length, and shows the same general type of organisa- 

 tion as the " Lagenostoma " series of ovules. The pollen- 

 chamber, however, docs not engage with the micropyle, 

 but opens and closes with a very perfect mechanism, some- 

 what reminiscent of the peristome and epiphragm of Poly- 

 trichum. The paper also deals with the relation of this 

 ovule to Heterangium Grievii, and with a new Crossotheca 

 which is attributed to the same plant. 



Physical Society, March 26, — Dr. C. Chree, F.R.S., 

 president, in the chair. — The production of steady elec- 

 trical oscillations in closed circuits, and a method of test- 

 ipg radio-telegraphic receivers : Dr. J. A. Fleming and 

 G. B. Dyke. By the use of two such nearly closed 

 oscillatory circuits, one being employed as a transmitting 

 station and the other as a receiving station, these being 

 placed at a distance of a few hundred yards from each 

 other, what is practically equivalent to radio-telegraphic 

 stations with open oscillators at very large distances can 

 be constructed. Methods were described for producing in 

 one of the closed circuits extremely constant damped 

 oscillations by means of an induction coil or transformer, 

 a sparli-gap on which a steady jet of air is allowed to 

 impinge, and a suitable mercury break. Means were 

 described for ascertaining when the current in this trans- 

 mitting circuit is constant. Instances were given of the 

 ease with which detectors of various types, such as a 

 magnetic detector, electrolytic detector, crystal detector, 

 and ionised gas detector, could be compared for relative 

 sensibility. — Effect of an air blast upon the spark discharge 

 of a condenser charged by an induction coil or trans- 

 former : Dr. J. A. Fleming^ and H. W. Richardson. 

 When an oscillatory discharge of a condenser takes place 

 across the spark-gap in the usual manner by charging the 

 condenser by an induction coil or transformer, the inter- 

 mittent spark which takes place is a complex effect. It 

 consists partly of a true condenser discharge and partly 

 of an alternating-current arc due to current coming directly 

 out of the induction coil or transformer. This arc dis- 

 charge is a source of difficulty in making accurate quanti- 

 tative measurements with electrical oscillations, and to 

 produce a uniform oscillatory discharge this true arc dis- 

 charge must be prevented or arrested. It was shown in 

 the paper that this can be done by a regulated air blast 



XO. 2060, VOL. 80] 



produced in any convenient manner, thrown upon the 

 spark-gap, provided that the spark-gap is small. The 

 paper also described experiments made to investigate the 

 efYect of breaking up the spark-gap into smaller spark- 

 gaps in series, both when the gaps were subjected to an 

 air blast and also without the air blast. — The action 

 between metals and acids and the conditions under which 

 mercury causes evolution of hydrogen : Dr. S. W. J. 

 Smith. The action between an acid and a metal, which 

 results in the replacement of hydrogen, can be formulated 

 without the aid of any hypothesis beyond the assumption 

 that it is approximately reversible. The mode of formula- 

 tion suggests a kinetic picture of the process by which 

 equilibrium is in certain cases attained. This was de- 

 scribed by the author, and it was pointed out that if a 

 steady state is reached, after a certain quantity of hydrogen 

 has been evolved, it will be defined by an equation of the 

 form aliM = bmii. In this, a and b are constants at a 

 given temperature, h and m are the concentrations of the 

 hydrogen ions and of the metal ions respectively in solu- 

 tion, and H and M are specific constants of hydrogen and 

 of the metal. The experiments described in the paper rnay 

 be regarded as an attempt to justify the above equation 

 when the metal is mercury. 



Zoological Society, .^pril 6. — Mr. F. Gillelt, vice-presi- 

 dent, in the chair. — Description of a new form of Ratel 

 (Mellivora) from Sierra Leone, with notes upon the de- 

 scribed African forms of this genus : R. I. Pocock. — An 

 ichthyosporidian causing a fatal disease in sea-trout : 

 Muriel Robertson. — A small series of fishes from 

 Christmas Island, collected by Dr. C. W. Andrews : 

 C. Tate Regan. Seven new species were described, com- 

 prising five blennies, a Pampeneus, and a Cirrhites. In 

 connection with the last-named, it was pointed out that 

 ! the Cirrhitida;, as defined and limited by Dr. Gunther, 

 with the addition of Haplodactylus, form a very natural 

 family.— Some new and little-known Hesperida; from 

 tropical West Africa : H. H. Druce. The paper contained 

 remarks on, and descriptions of, some new forms of these 

 butterflies lately obtained bv Mr. G. L. Bates on the Ja 

 River, Cameroons, and others from Nigeria. New species 

 of the genera Abantis, Acleros, Gorgyra, Parnara, and 

 Ceratrichia were described. 



P.iRIS. 



Academy of Sciences, April 13.— M. Bouchard in the 

 chair.— The diffraction of Hertzian waves : H. Poincare. 

 — .\ general solution of the speclroheliograph : H. 

 Desiandres. The spectroheliograph described, which is 

 installed at Meudon, consists of four different spectro- 

 lieliographs arranged round one collimator and astro- 

 nomical objective, and controlled by four synchronised 

 electric motors. These spectrographs are arranged for 

 different classes of work, some having two and others 

 three slits. The apparatus has already given interesting 

 results on the black filaments of the upper layers of the 

 solar atmosphere, especially the images of K3 and Ha.— 

 The transformations of the associated O networks : C. 

 Guichard.— The integration of certain functional in- 

 equalities : Arnaud Denjoy.— A problem of Fourier ; Henri 

 Larosse. — The action of a continuous current on sym- 

 metrical chains of electrolytes not having common ions : 

 M Chanoz. Studv of the gases disengaged by the action 

 of copper *alts on' steels: E. Goutal. Three steels were 

 studied, containing respectively 0-29, 064, and 1-38 per 

 cent, of carbon, the solution used for the attack being 

 that of the double chloride of copper and potassium con- 

 taining a few drops of hvdrochloric acid to the litre. The 

 carbon dioxide, carbon monoxide, and hydrocarbons evolved 

 were determined separately. The loss of carbon thus deter- 

 mined amounted to o-oi to 005 per cent., and this loss 

 is reduced bv about one-half if the carbon in the residue 

 is estimated 'without drving.— The quantitative analysis of 

 the occluded gases in the lava from the last eruptions of 

 Mt. Pel^e and Vesuvius : M. Grossmann. Estimations 

 were made of the total quantity of gas per 100 grams, and 

 figures given for the amounts of carbon dioxide, oxygen, 

 nkrogen, hydrogen, carbon monoxide, and methane. The 

 various products from Vesuvius show marked differences 

 In the quantitv and composition of the gases evolved. — 



