January i6, iJ^96j 



NATURE 



251 



the first place, by the green-blue rays ; and the red by the 

 yellow and red rays. Potassium, when excited by red 

 light, emitted light of a deep red colour. 



These experiments show that at least no very marked 

 deviations from Stokes' law exist. 



(4) Applications to Astrophysics. — We wish to point 

 out in a few words the importance, for astrophysical 

 problems, of the preceding observations concerning the 

 fluorescence of the metallic vapours. 



We know that in the atmosphere of the sun there exist 

 vapours of different metals which are radiated from the 

 sun ; these must also exhibit fluorescence, and that of a 

 bright nature. We must also remember that the intensity 

 of the exciting light in the region of the sun is much 

 greater than that near the earth's surface, and also 

 the same may be said of that of the fluorescent light. 

 These rays of fluorescence do not follow Kirchhoff^s 

 law. 



The radiated fluorescent light is made up of con- 

 inuous and fluted bands and single lines. By mixing 

 several metals together the continuous bands grouped 

 themselves and formed a continuous spectrum, the deli- 

 cate, and sometimes less recognisable, fluted bands, how- 

 ever, of several substances neutralised each other, and so 

 became invisible. Each of the sharp lines, on the other 

 hand, remained visible. We have thus, for example, a 

 very simple means of explaining the spectrum of the 

 corona, which consists of a continuous spectrum and 

 single bright lines. It is then unnecessary to assume 

 that luminosity is produced by a continuous agitation 

 depending on electrical oscillations ; agitations which, 

 nevertheless, play in many cases an important part. 

 Applications of these results may also be found to be 

 closely related to the theory of the chromosphere, certain 

 forms of prominences, &c. 



In- all astrophysical and other light phenomena (6'/r«/z/- 

 tingserscheimmgen) special discussions will be necessary, 

 not only from the point of view as to which portions 

 of the ray are the result alone of an increase in tempera- 

 ture, and which depend on "luminiscence" {lumittescenz), 

 but it must be especially made clear when we have before 

 us " photo-luminescence " and when " fluorescence." In 

 this case the conditions are relatively simple, and for 

 experiment easily accessible. 



(5) General Remarks.— T\\G:ca.?>e. of the fluorescence of 

 rarefied vapours of potassium and sodium as investigated 

 by us, might be the simplest possible when once the light- 

 producing molecules of the vapourous body under in- 

 vestigation are almost uninfluenced by the action of its 

 neighbours, if we disregard the short spaces of time 

 during which two or more molecules occupy in their 

 respective reactions. Then they behave just like the 

 molecules in bodies of a solid and liquid nature. 



Further, the vapours of sodium and potassium consist 

 of single atoms {einatotnig), so far at least as can be 

 judged from vapour densities established up to the pre- 

 sent. The fact, that in these vapours not only band- but 

 also line-spectra make their appearance, necessitates, 

 for the theoretical investigation of fluorescence, the adop- 

 tion of a new point of departure, more especially if the 

 fundamental movements of the molecules among them- 

 selves in fluorescence be investigated. 



(6) Result. — The fluorescence of sodium and potassium 

 vapours is bright ; the former green, the latter red. In 

 the fluorescence spectrum of sodium vapour continuous 

 and fluted bands appear, in addition to the bright sodium 

 line. 



Stokes' law is probably valid for the fluorescence of 

 the vapours of metals. The fluorescence of the vapours 

 of metals gives a means of explaining a series of astro- 

 physical phenomena. 



(Experiments with helium and argon are in process of 

 investigation.) 



NO. 1368, VOL. 53] 



NOTES. 



M. Chatin has been elected the new Vice-President of the 

 Paris Academy of Sciences, in the place of M. Cornu, who has 

 passed on to the presidency. 



The French Government has paid a graceful compliment to 

 Prof. Virchow, by nominating him Commander of the Legion 

 of Honour. 



The United States Congress has already made a good be- 

 ginning as to matters scientific and educational. One of the first 

 subjects to which attention was called, after the opening of the 

 current session, was the proposed joint meeting of the three 

 associations of English-speaking people for the advancement ot 

 science, at San Francisco in 1897, namely the Australasian, 

 American and British, following the Toronto meeting of the 

 British Association. A Congressman from Brooklyn presented a 

 memorial and petition from one of the original Fellows of the 

 American Association, setting forth the plan for such a meeting 

 of these associations, and requesting aid from Congress to put 

 the American Association on equal footing with the British in 

 regard to transportation of members across the continent, which 

 it is supposed that the Canadian Pacific Railway will furnish 

 nearly or quite free to the latter. The same member a few days 

 later introduced a resolution in favour of the metric system. 

 Should the three science associations succeed in holding a joint 

 meeting, this subject would well deserve careful consideration. 



Two appeals for funds to fit out Polar expeditions have lately 

 been made — one for support of Captain Jackson's scheme for the 

 exploration of the North- East passage, the other for means to 

 equip a British Antarctic expedition. Captain Jackson proposes 

 to determine whether the North-East passage from Europe to 

 China and America is really practicable to merchant vessels 

 properly fitted for the Northern Seas, and to make as many 

 scientific observations as the equipment of his expedition will 

 allow. If he cannot obtain funds to purchase and equip a suit- 

 able ship, he announces his intention to proceed to Polar regions 

 in his yacht Venture, a boat only thirty-seven feet long. The 

 Honorary Secretary of the Committee that appeals for support on 

 behalf of Captain Jackson's scheme is Mr. E. R. Suffling, Blom- 

 field Lodge, Portsdown Road, London, W. 



The Executive Committee for the British Antarctic Committee 

 hope to obtain ;[f 5000 to be expended on outfits and supplies for 

 twelve scientific men to spend a year in South Victoria Land. It 

 is proposed that these investigators shall be conveyed to Cape 

 Adair by a commercial expedition now being formed with the 

 object of operating near Victoria Land. The party is expected 

 to leave on September i next. After calling at Melbourne they 

 will sail direct to Cape Adair, which, under favourable circum- 

 stances, should be reached in about fourteen days. There they 

 will be landed with their outfit and instruments, and remain for 

 one year, after which period they will be called for and brought 

 back by the commercial party. The following is a general plan 

 of the proposed investigations to be carried on at Victoria Land 

 by the scientific members of the expedition: (i) A land party 

 will work towards the South Magnetic Pole, there to make 

 magnetical observations. (2) The coast-line of the open bay will 

 be surveyed, fjords and bays explored and sounded. (3) Zoo- 

 logical, botanical, mineralogical and geological collections will 

 be made. (4) Dredging. (5) liarometrical, thermometrical, 

 meteorological and pendulum observations. (6) Air and water 

 current observations. If this programme is only carried out in 

 part, valuable additions to scientific knowledge will undoubtedly 

 be obtained. There are many who are eager to labour in the 



