April 3, 19 19] 



NATURE 



99 



(c) the movement of these gases over the surface of 

 the metal. Nevertheless, the results of these re- 

 searches do not agree, and in order to obtain further 

 data the author instituted experiments described in 

 this paper. He deals in detail with the apparatus em- 

 ployed and the methods adopted in pursuing his 

 investigations, and gives the following conclusions as 

 the result of his work : — (i) The true volatilisation of 

 gold is so small as to be negligible at the temperatures 

 of industrial melting furnaces, say 1000° ta 1300° C. 

 It is difficult to measure with accuracy the 

 infinitesimal amounts volatilised at these tempera- 

 tures. (2) It is probable that the nature of the atmo- 

 sphere, provided that it is maintained unchanged, has 

 no effect on volatilisation. Even in a strong draught 

 the amount volatilised remains exceedingly small. 



(3) Certain gold alloys, when molten, take up oxygen 

 from atmospheres containing it, and will afterwards 

 spirt or effervesce in a reducing atmosphere until the 

 oxygen has been removed. Similarly, hydrogen, and 

 in a less degree carbon monoxide, are occluded by 

 such molten alloys, and the metal then spirts in an 

 oxidising atmosphere. In spirting, showers of 

 globules of the alloys of all sizes are thrown up, and 

 the smaller ones, Especially those of less than 

 0001 mm. in diameter, are carried away by any 

 draught, however slight, and are difficult to, recover. 

 They can. be collected by such a filter as cotton-wool. 



(4) The action is observable in all the alloys of gold 

 with, silver or copper. Even parted gold containing 

 I part per 1000 of silver is affected, though to a far less 

 degree than coinage alloys, gold-silver parting alloys, 

 and similar materials. Fine silver and its alloys with 

 copper also spirt freely. (5) It is this action which 

 causes the unrecovered losses in melting such alloys 

 in crucibles without a cover of slag. — W. S. Curteis : 

 Cobar stope-measurement methods. This paper deals 

 with the methods adopted in measuring the stopes of 

 the Great Cobar Mine" for the purpose of working out 

 the pav-sheets of the miners fortnightly, in place of 

 the former practice of paying in a final settlement 

 when the ore was withdrawn from the stope. With 

 this end in view two different methods were em- 

 ploved, according to the form and peculiarities of the 

 stope outline, and the author sets out the two systems 

 of calculation in great detail, accompanied by sketches 

 in elucidation. It is found that the measurements 

 required for this purpose are also capable of being 

 utilised for other purposes, including the calculation 

 of ore reserves. 



Paris. 

 Academy of Sciences, March 10. — M. L^on 

 Guignard in the chair.— L. Lecornu : The flow of 

 liquids. A discussion of a theorem published by 

 Hugoniot .in 1886.— M. Hamy : The study of 

 the perturbations of the optical axis of a 

 meridian telescope. An account of the method of 

 determining the constants defined in a previous com- 

 munication.— L. Maquenne and E. Demoussy : A very 

 sensitive reaction for copper. Application to the 

 analyses of ashes and arable earths. The reaction 

 is based on a blue coloration developed by traces of 

 copper salts by the action of a ferro-cyanide in 

 presence of a trace of a zinc salt. Iron interferes, 

 and details of its method of removal are given. The 

 reaction can detect i milligram of copper in a litre of 

 solution. — H. Parenty : A steam expansion controller, 

 the reduced pressure increasing with the amount 

 required by the main.— G. E. Hale was elected a 

 foreign associate in succession to A. von Baeyer. — J. 

 Drach : The intet^ration, bv quadratures, of the 

 equation d'v/^.'c'='F(x, y).— P. Fatoa : Singular lines 

 of analytical functions.— G. Julia : A general property 

 of entire functions related to Picard's theorem. — A. 



NO. 2579, VOL. 103] 



Buhl : The exchange of the parameter and the argu- 

 ment. Analogies with the reduction of double 

 integrals of the second species. — F. Michaux : Emis- 

 sive theories and the Doppler-Fizeau principle. The 

 fact that the Doppler formula is verified when the 

 wave-length is measured by an interferometer is not 

 in agreement with the theories of Tolman and 

 Thomson-Stewart, but is in accord with either the 

 theory of Ritz or that of Lorentz.— J. Rey : The 

 physical properties of i>etrol vapour. For a petrol 

 density of o-8 at 0° C. the characteristic equation of 

 the vapour is sensibly of the form />(v + a) = RT, 

 where a is 0024 and R 5-09. A formula is also 

 deduced for the flow of superheated petrol vapour. — 

 E. Cornec : The spectrographic study of the ashes of 

 marine plants. A list is given of nineteen elements 

 recognised by the spectroscope in the ashes of sea- 

 weed. Gold, bismuth, gallium, and germanium exist 

 only in the state of spectroscopic trace. The elements 

 not previously recognised in marine plants include 

 antimony, germanium, glucinum, titanium, tungsten, 

 and vanadium.— A. Bigot : The geology of the Col du 

 Cotentin. — P. Gu6rin : IJrera humblotii and its affini- 

 ties. — H. Coupin : The absorbing power of the root- 

 tip. Contrary to the view currently held, the tip of 

 the root can absorb water in sufficient quantity to 

 produce germination.— M. Molliard : Egg-albumin 

 constitutes a complete food for Isaria densa. — G. 

 RiviJre and G. Bailhache : Amygdalopersica formonti. 

 —]. Chifflot : The secretory canals of some Ges- 

 neraceae, and in particular o'f those of Monophyllaea 

 horsiieldii.—M. Mirande : The cvtological formation 

 of starch and of oil in Chara.— A. Licaillon : The 

 changes observed in the reproduction and develop- 

 ment in Chinese polyvoltin silkworms when trans- 

 ported and raised in France. 



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