574 



NATURE 



[April 13, 1905 



the relalive humidity rises, decreases with increasing wind 

 strength, and is greater with a falling than with a rising 

 barometer. All these facts support Elster and Geitel's theory 

 that the source of the emanation in the atmosphere is the 

 soil of the ground. Those meteorological conditions which 

 prevent the air immediately above the ground from ascend- 

 ing tend to increase the radio-activity ; on the contrary, all 

 those conditions which cause a rapid circulation of the air 

 greatly reduce the radio-activity when measured in the 

 lower atmosphere. 



Observ.atioxs .\t H.ammerkest. — The mean values of the 

 radio-activity were found to be lower at Hammerfest on 

 tne coast than at Karasjok inland. The most important 

 result of the Hammerfest measurements was the great 

 difference between the radio-activity of the air from the 

 sea and that from the land. The mean radio-activity with 

 a wind from the sea was only 6, while with a land breeze 

 the mean was 72. 



March 16. — '" .\ New Radio-active Element, which 

 Evolves Thorium Emanation." Preliminary Communi- 

 cation. By Dr. O. Hahn. Communicated bv Sir William 

 Ramsay, K.C.B., F.R.S. 



The radio-active preparation was gained from barium 

 radium bromide, obtained from thorianite from Ceylon, 

 while fractionating it in order to separate the radium. It 

 collected along with small traces of iron and other impuri- 

 ties in the more soluble portions, and was precipitated by 

 ammonia. From this preparation a quantity of about 

 10 mg. of a strongly radio-activi' oxalate was obtained, 

 giving off a strong emanation and imparting bright 

 lumtnositv to sensitive screens. The emanation was found 

 to be identical with that of thorium ; different samples 

 gave for the half-period of decay from 52 to 55 seconds. 

 For the half-period of the induced activity somewhat more 

 than ii| hours was found. The emanation given off by 

 the 10 mg. of the oxalate, dissolved in hydrochloric acid, 

 corresponds in intensity to more than that of a kilogram 

 of thorium in solution ; consequently it was more than 

 100,000 times stronger than the common thorium eman- 

 ation when compared weight for weight. Further work 

 led to the separation of about 20 mg. of a substance 

 giving nearly 250,000 times more emanation than thorium. 



Whether this active substance is the constant radio- 

 active constituent of thorium preparations, or whether it 

 is another new radio-active element, remains still un- 

 decided. It is hoped that an even more strongly radio- 

 active product may be obtained, and that it may be 

 possible to describe more in detail the properties of the 

 substance. 



Recent researches would appear to show that the amount 

 of this substance in soil is comparable with, but still 

 considerably smaller than, radium. 



March 30. — " The Rdle of Diffusion in the Catalysis of 

 Hydrogen Peroxide by Colloidal Platinum." By Dr. 

 George Senter. Communicated bv Sir William Ramsav, 

 K.C.B., F.R.S. 



The deviations from the simple logarithmic formula in 

 the catalytic decomposition of hydrogen peroxide by 

 colloidal platinum are probably due to disturbances caused 

 bv convection currents. When the velocity-constant calcu- 

 lated on Nernst's diffusion hypothesis is great compared 

 with the chemical velocity-constant, increased convection 

 can produce no appreciable effect on the observed reaction- 

 velocity. 



In the case under consideration, therefore, since in- 

 creased convection modifies the observed reaction-velocity, 

 there must be some error in the assumptions which lead 

 to the conclusion that the diffusion velocity-constant is 

 great in comparison with the chemical velocity-constant. 

 This error is probably to be found in the assumption that 

 the whole surface of the platinum is, under orainary con- 

 ditions, active towards hydrogen peroxide. 



It cannot be claimed, from the above considerations, that 

 Nernst's hypothesis is true for the platinum catalysis, but 

 only that the diffusion-velocity is not great in comparison 

 with the chemical velocity. Other considerations, how- 

 ever, such as the small value of the temperature 

 coefficient, make it probable that the above hypo- 

 thesis does apply to this particular action. Further 

 support for this view may, perhaps, be found in the faci 



NO. 1850, VOL. 71] 



that the deviations from the simple logarithmic law in 

 catalysis by platinum have their exact analogy in the 

 hiumase catalysis. On the " chemical " velocity hypo- 

 thesis it would seem rather remarkable that two catalysers 

 of so different origin should show exactly similar behaviour, 

 but this becomes at once intelligible on Nernst's hypo- 

 thesis, according to which the chemical action plays quite 

 a secondary part in the reaction-velocities in question. 



Mineralogical Society, March 15. — Piof. II. A. Miers, 

 F.R.S., president, in the chair. — Description of the big 

 diamond recentiv found at the Premier ^line, Transvaal : 

 Dr. F. H. Hatch and Ur. G. S. Corstorphine. The 

 stone weighed more than 13 lb., and its greatest linear 

 dimension was 4 inches. It was part (probably less than 

 half) of a distorted octahedral crystal. — On some new 

 mineral localities in Cornwall and Devon : A. E. I. M. 

 Russell. \n account was given of various new finds of 

 the minerals anatase, scheelite, wolframite, childrenite, 

 apatite, and connellite. — On a crystal of phenakite from 

 .\frica : L. J. Spencer. This crystal, which was trans- 

 parent and rich in faces, was brought back together with 

 crystals of tourmaline, corundum, and amethyst, , by the 

 Rev. .\. North Wood from the L'sagara country in 

 German East .\frica. — Notes on various minerals from the 

 Binnenthal, Switzerland ; G. T. Prior and G. F. Herbert 

 Smith. Further crystallographic and chemical details 

 were given of the three new red minerals from the 

 Binnenthal originally described by R. H. Solly, and 

 named by him Smithite (after G. F. Herbert Smith), 

 Hutchinsonite (after .■\. Hutchinson), and Trechmannite 

 (after C. O. Trechmann). Smithite is a sulpharsenite of 

 silver having the composition represented by the formula 

 .Ag.AsS, ; it is monoclinic with a : b : £ = 2.2205 • ' ■ '^oTC 

 i3 78° 40'. .\ perfect cleavage parallel to 100 distinguishes 

 it from the other two red minerals. Hutchinsonite is 

 rhombic with a : b : c = 1-6356 : i : 0-7540. A prominent 

 form is 140. Trechmannite is rhombohedral with 

 = 0-7265. The symmetry is the same as that of quartz. 

 — On a new o.xychloride of copper from Sierra Gorda. 

 Chili : G. T. Prior and G. F. Herbert Smith. This new 

 mineral, to which the mune p.-iratacamite was given, has 

 the same chemical composition as atacamite, but begins to 

 lose its water at a higher temperature than that mineral. 

 It is pseudorhombohedral with rr' =83° nearly. Twins 

 about r are common. It displays optical anomalies, for 

 minute fragments under the microscope are found to be 

 biaxial. — On Dundasite from North Wales : G. T. Prior. 

 The mineral was found b)' Mr. H. F. Collins in the Welsh 

 Foxsdale Mine, Trefriw, Caernarvonshire : it occurs in 

 white silky radiating tufts on cerussite with allophane : 

 analysis showed it to be identical with Dundasite, hitherto 

 known onlv from Dundas, Tasmania. A probable formula 

 is PbO.Ai;o,.2CO,.4H,0 or PbH,(CO,),..Al,.0H,. 



Zoological Society, March 21. - Mr G. A. Boulenger, 

 F.R.S., vice-president, in the chair. — Exhibits. — Photo- 

 graph of a wounded Oryx (Oryx beisa) hiding in under- 

 growth of wood in its native haunts, in order to show the 

 protective nature of the coloration of the animal : F. 

 Gillett. — .'\ series of pencil sketches of fishes of the Rio 

 Negro and its tributaries made by Dr. A. R. Wallace 



about fifty years ago : C. Tate Regan Radiograph of a ' 



living snake showing the skeletons of two frogs it had 

 swallowed son)e hours previiiusly : M. Yearsley. — Skulls of 

 the fallow deer {Dama vulgaris) and the red deer {Cerviis 

 I'laphus) showing arrest of the growth of the antlers due to 

 complete or partial castration : R. E. Holding. — Papers. — 

 Effects of castration upon the horns of the prongbuck 

 ( Iii(i7<icii/>r(i iiKicnVaiio) : K. I. Pocock. The effects of 

 the operation were curvature in growth, prevention of 

 exuviation, and practical suppression of the anterior tyne. 

 -The mammals and birds of Liberia: Sir Harry 

 Johnston, G.C.M.G., K.C.B. .\lthough Liberia was not 

 marked off clearly by any natural features from either 

 Sierra Leone on the one hand or the Ivory Coast on the 

 other, it possessed a certain distinctness and a slight 

 degree of peculiarity as regards its flora and fauna. As 

 regards mammals and birds. Liberia was, to a great 

 extent, a meeting-place for the forms of northern Guinea 

 (Sierra Leone to the Gambial and those of the Gold Coast, 

 the Niger Delta, and the Cameroons. The species of 



