December 5, 1895] 



NATUHE 



recueillir le prix de leurs efforts, ceux qui en ont ^tudie les 

 resultats, ont rendu des services dont nous leur sommes pro- 

 fondement reconnaissants. Le monument scientifique ainsi 

 «leve par les savants anglais constitue un titre de gloire dont 

 «ne nation a le droit d'etre fiere." 



The contributors to this gigantic Report are, for the most 

 part, natives of thi United Kingdom and the British Colonies, 

 but the scientific men of nearly every civilised State are repre- 

 sented among the authors. The British and foreign contributors 

 are seventy-six in number, and many scientific men whose names 

 ■do not appear on the title-pages of the special memoirs have 

 taken part in the physical and chemical researches performed in 

 •connection with the work of the expedition. Among the con- 

 tributors we find the names'of Alexander Agassiz, Ernst Haeckel, 

 P. G. Tait, G. O. Sars, F. E. Schulze, T. H. Huxley, Rudolph 

 Bergh, A. v. Kolliker, A. Renard, W. K. Brooks, N. N. Pole- 

 jeff, Th. Studer, A. A. W. Hubrecht, W. Dittmar, Sir William 

 Turner, A. Giinther. Before the end of the present meeting I 

 shall have the pleasure of presenting to Mr. Murray one of the 

 Royal medals, which has been awarded to him by the Council 

 of the Royal Society, to mark their appreciation of his editor- 

 ship of this great work, and of his own scientific contributions 

 to it. 



In my Presidential Address of last year I took occasion to refer 

 to Lord Rayleigh's discovery that the gas which remains when 

 •oxygen, vapour of water, and carbonic acid are removed from 

 common air, is denser than nitrogen extracted from chemical 

 compounds ; and I was then able to tell you of the consequent 

 •discovery that our atmosphere contains a fifth constituent which 

 is denser than nitrogen. This discovery had been thoroughly 

 established by Rayleigh, in association with Ramsay, who had 

 joined him in the work ; but no details had then been published. 

 They had succeeded in isolating the new constituent by extract- 

 ing all the four previously known constituents (oxygen, nitrogen, 

 aqueous vapour, carbonic acid) from air, and they were energeti- 

 cally at work with a view to discovering its properties. I con- 

 cluded my last year's Address by expressing the hope that their 

 work would give us, " before the next Anniversary Meeting of 

 the Royal Society, much knowledge of the properties, both 

 physical and chemical, of the hitherto unknown and still anony- 

 mous fifth constituent of our atmosphere." That hope, as you 

 all know, has been splendidly fulfilled. They early discovered a 

 mame for it, Argon, because exhaustive chemical mvestigation 

 gave them no evidence of its chemical combination with any 

 other known element. They found its density to be very high, 

 20 (that of oxygen being called i6), and the ratio of its specific 

 heats i|. Olzewski. experimenting on a specimen sent to him 

 by Ramsay, succeeded in liquefying it, and found its critical 

 pressure to be 50 '6 atmospheres, and its critical temperature 

 - 121°. These results were communicated in a joint paper by 

 Rayleigh and Ramsay to the Royal Society at a memorable 

 meeting, held in the theatre of the University of London, be- 

 cause our ordinary meeting-room was not large enough to contain 

 all who wished to hear it. It will be gratifying to Fellows of 

 the Royal Society to know that the Smithsonian Institution of 

 Washington gave to Lord Rayleigh and Prof. William Ramsay 

 the first Hodgkins' prize for their " Memoir on Argon : a 

 New Constituent of the Atmosphere." This memoir had been 

 communicated to Washington before the end of December 1894. 

 Since the dates of those first communications much work has 

 been done by various observers on the spectrum analysis of argon. 

 In a communication by Rayleigh to the recent meeting of the 

 British Association, we find a very accurate determination of its 

 refractive index and its viscosity. Ramsay, in trying for clues to 

 compounds of argon, had his attention called by Mr. Miers (of 

 the British Museum) to a paper by Hillebrande, telling that 

 cleveite (a rare Norwegian mineral which consists chiefly of 

 uranate of lead) gives out 2 per cent, of gas, supposed to be 

 nitrogen, when warmed with weak sulphuric acid. Ramsay, 

 thinking the so-called nitrogen might turn out to be argon, ex- 

 perimented on the mineral. He found that the gas evolved, by 

 heating it in sulphuric acid, contained a trace of nitrogen, which 

 he removed by the Cavendish process of sparking with oxygen 

 in presence of alkaline liquor. The residue was proved by the 

 spectrum test to contain argon, but to contain also another gas, 

 not argon, showing itself by a brilliant yellow line. This line 

 was identified by Crookes as the " helium line," discovered thirty 

 years ago by Lockyer, who, finding it to have been not discovered 

 . in the spectrum of any terrestrial substance spectroscopically ex- 

 • aiuined up to that time, attributed it to a substance in the sun's 



atmosphere, which he called helium. Thus, a substance, dis- 

 covered thirty years ago in the sun's atmosphere, and accordingly 

 named from the sun, has been found in a terrestrial mineral by 

 Ramsay, in his quest after argon. Having got helium into his 

 laboratory, he found its density to be less than 3-9 (ultimately 

 reduced to 2), and, therefore, less than one-fifth (about one- 

 tenth) of that of argon. He sent a specimen to Olzewski, who 

 found (Nature, October 3, 1895) 'hat the treatment by which 

 he had succeeded in liquefying hydrogen — namely, compressing 

 with a pressure of 140 atmospheres, cooling to the temperature 

 of liquid air boiling at low pressure, and then expanding 

 suddenly, showed no signs of liquefying helium. 



Considering the uncertainty as to the density of the gas in which 

 helium was identified, and the multiplicity of spectrums found for 

 it by various experimenters, Lockyer, who experimented on some 

 eighty minerals, and found the yellow line of helium in sixteen 

 of them, thinks it most probable that it is not a single gas that is 

 extracted either from cleveite or the other minerals, but a mix- 

 ture of gases of which helium is one ; and this view was supported 

 by Runge and Paschen in their admirable spectroscopic analysis 

 of argon and helium, communicated to the British Association 

 (" British Association Report," Section A, September 18, 1895) 

 at its recent meeting at Ipswich. It seems too early to feel sure 

 that the helium found by Ramsay in the gas from cleveite, if 

 perfectly purified of nitrogen and other known gases, is a single 

 gas, or is a mixture or combination of .several. Before another 

 Anniversary Meeting of the Royal Society, it is probable that we 

 shall have certain knowledge, without any doubt, as to this 

 question. Meantime, at our present Anniversary, we may be 

 satisfied to feel that if there are several new gases, of which one, 

 at least, has density less than a quarter of that of oxygen, the 

 discovery will be several times as interesting as if the helium 

 now discovered proves to be only one gas. 



Copley Medal. 

 Dr. Karl Weierstrass, For. Mem. R.S. 



Dr. Karl Weierstrass is distinguished for his investigations in 

 pure mathematics, extending over a period of fifty years. He 

 is one of the great pure mathematicians of the century. 



Among his researches, dealing with many branches of the 

 science in which his work is of significant effect, may be spe- 

 cially mentioned : — 



(i. ) His investigations in pure algebra, particularly in relation 

 to functions of real variables, to the considerations of conver- 

 gence and divergence of series and products, and to the theory 

 of bilinear and quadratic forms. 



(ii.) His contributions to the general theory of functions ot 

 complex variables. This subject he has developed from its foun- 

 dations, and has re-established it on a new basis, so that much 

 of it is his creation. The extensions which he has made to this 

 theory have of themselves proved sufficient to secure for him the 

 distinction of an acknowledged master. 



(iii.) His work in the theory of periodic functions. In parti- 

 cular, the advances made by him in the theory of Abelian trans- 

 cendents, mark the chief algebraical development since the 

 time of Abel and Jacobi, and they have stimulated others to 

 further developments. Also the valuable advances made by him 

 in the theory of elliptic functions have been fruitful and sugges- 

 tive as the starting-points for researches by a number of dis- 

 tinguished mathematicians. 



(iv.) His work in the calculus of variations, the best known 

 published part of which relates to the theory of minimal sur- 

 faces. 



Not least remarkable among his claims to originality is the 

 method of proof which he has introduced in his investigations ; 

 he has associated a vigour and a strictness with the minutest 

 details of his proofs that have not merely led to the sound estab- 

 lishment of propositions, but have indicated limitations and have 

 suggested new ideas. 



Royal Medal. 



Dr. John Murray. 

 To Dr. John Murray one of the Royal Medals is awarded for 

 his energetic and successful editorship of the Report of the 

 C/^a//<f«^«fr Expedition, and for his own large contributions to 

 the work of the expedition and to the scientific jxipers embodied 

 in the Report: In this matter Dr. Murray's labours are recog- 

 nised universally as having been of extreme value to zoological 

 science. His own contributions to the elucidation of the 

 material brought home by the Challenger have been of great 



NO. 1362, VOL. 53] 



