May 28, 1908] 



NA TURE 



95 



'- was 54,000 feet, and on that occasion the south-west anti- 

 trade wind was apparently penetrated and a north-west 

 upper current encountered. — Balloon experiments in 

 Barbados, November 6-8, 1007 : Prof. J. P. d'Albu- 

 querque. — Observations on the colour of lightning made 

 at Epsom, 1903-7 : S. C. Russell. The author had for 

 the past five years kept a record of the colours or series 

 of colours noted during each thunderstorm or display of 

 sheet lightning, and tabulated them under their respective 

 colour. He had thus results of observations of fork 

 lightning made during fifty-seven thunderstorms, and 

 seventy-eight observations of sheet lightning. It appears 

 that in fork lightning red is the colour of the most frequent 

 occurrence, and this is followed closely by blue, the least 

 frequent colours being orange and green, ^^'hite is of the 

 greatest frequence in sheet lightning, red and yellow being 

 next. It seems that the presence of hail, when occurring 

 in association with a thunderstorm, is intimately connoctecl 

 with blue lightning. 



Institution of Mining and Metallurgy, May 21. — Mr. 



Alfred James, president, in the chair. — The electrical equip- 

 ment of gold mines : H. J. S. Heather. Continued dis- 

 cussion on this paper. — The behaviour of tellurium in assay- 

 ing : Sydney W. Smith. An examination of the behaviour 

 of this substance during pot-fusion, scorification, and 

 cupellation in order that some reasons may be offered for 

 taking the precautions which are generally regarded as 

 necessary to ensure successful work. The paper describes 

 a number of careful observations made with this end in 

 view, and a summary of the conclusions arrived at is given. 

 — The average rate of accumulation and absorption of gold 

 amalgam by copper plates : Edward Halse. The absorp- 

 tion and accumulation of gold on copper plates : \V. F. K. 

 Thomae. These two papers deal with the same subject, 

 the general conclusion of the two authors being that the 

 absorption of gold by copper plates may be ignored by 

 the mill-man in view of its small importance. In no case 

 does the average rate appear to exceed a fraction of a 

 grain per ton milled, and in the case of ore containing 

 coarse gold it is practically nil. The authors look at this 

 matter from somewhat different points of view, Mr. 

 Thomae especially thinking that further data might be 

 worth placing on record. — A journey to Central .^sia : A. 

 Adiassewich. This paper records the results of travels 

 in Central Asia, with special reference to the position and 

 prospects of the mining industry there. After a general 

 description of the conditions of mining, the author passes 

 m review the leading districts, Orenburg, the Khirgiz 

 Steppes, &c., and gives details of the occurrence of gold, 

 silver, copper, iron and other ores, coal, and petroleum. 



Paris. 



Acadetny of Sciences. May iS.— M. H. Becquerel in the 

 chair. — The hovering flight of birds : Marcel Deprez. — 

 The turning of aeroplanes : Paul Renard. To turn an 

 aeroplane requires that the apparatus should incline trans- 

 versely a given amount ; it will, hi addition, usually have 

 the effect of lowering the trajectory. Before making a 

 turn it will therefore be necessary to rise if the original, 

 height is to be maintained at the end of the turn. — The 

 profile of the polar masses of dynamos : Paul Girault. — 

 The ultramicroscopic examination of charged centres in 

 suspension in gases : M. de Brogriie. — The re-combination 

 of the ions in dielectrics : P. Langevin. On the supposi- 

 tion that in gases the re-combination of the ions with 

 contrary signs is due to the attraction of their electric 

 charges, the author has shown in an earlier paper that 



relation - ;-, ^i =f holds, in which a is the co- 



4irU-] -(- /■.,)- 



efficient of re-combination, fcj and fej the mobilities of the 

 positive and negative ions. In the present paper the 

 application of this formula to the case of solid dielectrics 

 is considered, and a simple method described of determin- 

 ing €. — The influence of the surrounding atmosphere on 

 the friction between solid bodies : F. Charron. The 

 presence of moisture, benzene vapour, or alcohol vapour 

 'tn the air reduces the friction, but no variation could be 

 observed when the air round the moving parts was re- 

 placed by dry hydrogen, carbon dioxide, or ethylene. — 



NO. 2013, VOL. 78] 



The auto-excitation of a tri-phase alternator by means of 

 electric valves : C. Limb. — The differences of contact 

 potential between metals and liquids : L. Bloch. The 

 apparent difference of contact potential between metal and 

 liquid is smaller for alkaline solutions than for water, and 

 smaller for water than for acid solutions. Salts give 

 effects differing only slightly from water. The method is 

 sensitive enough to detect traces of acid and alkali beyond 

 the reach of detection by colour reagents. — The radiography 

 of the lungs and stomach of the foetus and still-born 

 infants : M. Bouchacourt. In infants whose lungs have 

 been filled with air, the lungs show definitely in the radio- 

 graph, but the usual practice of artificial inspiration in the 

 case of infants apparently still-born may lead to the 

 erroneous conclusion that the child has lived. The causes 

 of the visibility of the stomach in the radiograph are also 

 discussed. — Observation on the time required for the solu- 

 tion of substances : Gaston Gaillard. The substances 

 studied were sodium thiosulphate, sugar, and sodium 

 sulphate. The effect of the size of the crystal and rate of 

 agitation have a great influence on the results, and it is 

 only when these two factors are kept as constant as 

 possible that comparative measurements can be obtained. 

 — .\ photographic action of infra-red light : h. Gargam 

 de Moncetz. The gelatinobrbmide plates were fogged by 

 the X-rays previous to the exposure to the red rays, the 

 light being filtered through a solution of iodine in carbon 

 bisulphide capable of cutting off all rays between 800 K and 

 4 X. The plate showed clear effects of the exposure for 

 wave-lengths between 920 A. and 1350 A.. The preliminary 

 fogging of the plates by ordinary light instead of by the 

 X-^rays did not give these results. — The kinematographic 

 study of the Brovvnian movements : Victor Henri. The 

 path described by a particle, as shown by these experi- 

 ments, was very complex ; it varies from one particle to 

 another, and is absolutely independent for each particle 

 even when two particle> only 2 /i apart are compared. 

 The trajectory often shows abrupt changes of direction. 

 The displacements measured for 005 second were compared 

 with those deduced by Einstein's formula, and were found 

 to be about four times greater than the latter. — The iodo- 

 mercurates of thorium and aluminium : A. Duboin. The 

 preparation and properties of ThI,,,5HgI,,i8H„0 and 

 AII,,HgI,,8H,0 are described. — The definite compounds of 

 silicon and palladium : Paul Lebeau and Pierre Jolibois. 

 .Silicon and palladium unite directly with evolution of 

 heat, giving rise to two definite silicates, Pd,Si and PdSi, 

 the first of which has been separated and analysed. The 

 existence of the other silicide has been deduced from the 

 determination of the fusibility curve and the metallographic 

 study of the ingots obtained. These silicides are analogous 

 to the platinum silicides already known. — A method for 

 the volumetric estimation of tartaric acid in argol and 

 cream of tartar : Em. Pozzi-Escot. The method is based 

 on the insolubility of barium tartrate in alcohol, and the 

 solubility of barium bromide in the same solvent. The 

 excess of barium used is converted into the oxalate, and 

 the latter determined with potassium permanganate. — The 

 elimination of carbon monoxide from coal gas : Leo 

 ; Vigrnon. Details of laboratory experiments on three 

 I methods are given : the conversion into methane by reduced 

 nickel, the transformation into carbon dioxide by heating 

 with oxide of iron at definite temperatures, and the direct 

 absorption with cuprous chloride. The question of the 

 cost of treatment or the value of the gas after such treat- 

 ment is not dealt with by the author. — Proparffylcarbinol : 

 MM. Lespieau and Pariselie. Starting with the ester 

 CH„Br— CHBr— CM,— CH,.OCH„ this is successively con- 

 verted into 1:2: 4-tribromobutane by the action of hydro- 

 bromic acid, 2 : 4-dibromobutene, from the preceding by 

 the action of potash, the alcohol, CH,=CBr— CH,.CH,OH, 

 and the sought for acetylenic alcohol, 



CH = C— CH,.CH,OH. 



— The mixed trihalogen derivatives of methane : \'. Auger. 

 A description of the preparation and properties of 

 CHCl.I, CHCIL, CHBrJ. and CHBrL.^The constitu- 

 tion of the combinations of tetramethyl-diamino-benzhydrol 

 with some methylenic derivatives : R. Fosse. — Some 

 orthobenzylated colouring matters from triphenylmethane : 



