July i i, 1895] 



NATURE 



btxiies, and not with one. That was ver)' important ; but you will 

 see from the photograph, that it is very unlike the spectrum of 

 nebulie, so that it required a certain amount of faith when the 

 spectrum was observed to be such as you see it here, to suppose 

 that after a certain time, when the action which produced the 

 i^realer luminosity was reduced and the light toned down, we 

 should eventually get the spectrum of a nebula. 



Well, as a matter of fact, the Xova reappeared in .\ugust 

 1S92, and was observed to have increased in brightness from the 

 16th magnitude in April to about 9th magnitude. What, then, 

 w<as the spectnim ? It had almost completely changed ; and 

 among the first to observe the new spectrum was I'rof. Campbell, 

 of the Lick Observatory. This observer then stated that "the 

 spectrum resembles that of the planetary nebula;." In the 

 following month the spectrum was also observed by Drs. 

 Copeland and Lohse, and their observations seemed to them to 

 "prove beyond doubt that Nova .\urigoe is now mainly shining 

 ;us a luminous gas nebula." The most striking evidence on this 

 point, however, is that afforded by the photographic investiga- 

 tions of \"on Gothard. He not only shows us the photographic 



17 Sept. 



< i.C . 49D4. 



-5 Sept. 



i;.c. 4373. 



13 Oct. 



■ 5 ■ H5 



G.C. 4514. 

 14 Oct. 



(j.C. 4628. 

 =7 Oct. 



N'.ti.C. 7027 

 2= Oct. 



X.G.C. 6891 

 27 Oct. 



N.G.C. 6884 

 28 Oct. 



New Star 

 aS Oct. 



Hy H« Hi 



Nebular lines. 



Fi<-,. 37.— Tile spectrum of the new star in -Auriga, as compared with the 

 spectra of planetary nebulae (Gothard). 



siK-clrum of the new star at this stage of its history, but gives 

 us also the spectra of several nebula; to compare with it ; and it 

 IS evident that we were certainly dealing, in the case of the 

 IVova, with the same spectrum as in the nebukv. Dr. Gothard, 

 at least, wa.s satisfied on this point, and stated that " the 

 Jihysiral aiul chemical state of the new star resembles at present 

 (September and October 1892) that of the planetary nebula;.'' 



So you see we get, first of all, the hard fact that the spectrum 

 iiidicated the e.\istence of two Ijodies ; and then the very much 

 harder fact for some, that, after the war was over, we got back 

 to the condition of the nebuUv. I need not tell you th.at there 

 IS not universal agreement on this i>oint. and chief among those 

 who (1„ nnt yet acknowledge it are Dr. and Mrs. Iluggins. 

 Writing of Iheir observations of Kebruary 189J, they s.ay : " We 



f 1.^" t'"^""^ "' l"''^'"^"' "'•'i Kf'-'-'^l reserve, as our knowledge 

 ot ihe Nova is very incomplete ; biU we do not regaril the 

 circumstance that the two groups of lines above described fall 

 near the positions of the two principal nebular lines as sufficient 

 to show any connection between the present physical state of 

 ihc Nova and that of a nebula of the class which gives these 

 lines. "^ 



NO. 1341, VOL. 52] 



But I may say, at all events, that I have the great authority of 

 the names of Campbell, Copeland, and Gothard, who state that 

 they have certainly observed the spectrum to be that of the 

 nebulje, and in reply to Dr. Huggins, I'rof. Campbell says ; " If 

 I the spectrum is not conceded to be neljular, I must ask what else 

 we should expect to find in that spectrum, if it were nebular?" 

 The answer to that is, that you would not expect to find anjlhing 

 else because it is all there already. In fact, out of nineteen 

 lines observed or i>hotographed by I'rof. Campbell in the 

 spectrum of the Nova, eighteen correspond perfectly with nebular 

 lines. " Therefore the spectrum is nebular, and the fact that 

 the lines have remained broad, or may have remained multiple, 

 does not militate against the theory." 



Further, there is even telescopic and photographic evidence of 

 the fact that Nova .Auriga' liecame a nebula. Dr. Max Wolf's 

 photographs of the Nova and its surroundings in 1893, resulted 

 in the discovery of a number of new diffuse nebula; in its vicinity, 

 " and there even appeared to be traces of nebulous appendages 

 proceeding from the star itself.'' 



Another new star appeared in the southern constellation Norma 

 in 1893. This was discovered on (.)ctober 26, on a photograph 

 taken at Arequipa, Peru, on July 10, 1893. P'ortunately the 

 photograph was one showing the spectra of stars instead of the 

 simple images of the stars themselves, and the spectrum was seen 

 to be identical with that of Nova .Auriga;. Even more important 

 were the obser\'ations of Campbell in February and March 1S94, 

 when the star was about loth magnitude. .\s the result of his 

 work, he stated that " there can be no doubt that the spectrum of 

 Nova Norm* is nebular.'' 



T. Norman Lockyer. 



( To he L'ONliinu-d. ) 



THE FLUORESCENCE OF ARGON, AND ITS 

 COMBINATION WITH THE ELEMENTS 

 OF BENZENES 



AT BERTHELOT read the following paper, containing 

 observations by M. Deslandres and himself, before a 

 recent meeting of the Paris .Academy of Sciences : — 



I have thought it useful to study more closely the conditions of 

 the combination w ith benzene under the influence of the silent 

 discharge and those of the special fluorescence which accom- 

 panies it. 



M. Deslandres, whose great competence in spectroscopic 

 questions the Academy is w ell aware of, has been kind enough to 

 help me in these new determinations, made with higher dis- 

 persion, and rigorously determined by photography. It is my 

 duty to thank him here for this long and laborious work. 



We must remember that the combination of argon with the 

 elements of benzene, under the influence of the silent discharge, 

 is a slow process ; according to the present research, it is accom- 

 plished with the help of mercury, which intervenes under the 

 form of a volatile compound. The use of very frequent dis- 

 charges appears not to modify the general characters of the 

 reaction. 



At the beginning, nothing is seen in daylight, and it is only in 

 a dark room that one perceives a feeble violet glow, similar, in 

 its intensity, to that which the discharge develops generally in 

 gaseous systems. .At the end of an hour, when in a dark room, 

 a green glimmer is seen, which occupies the middle of the 

 interval between the spirals of the platinum l>and wound round 

 the discharge tube, the luminous spectrum gives two yellow 

 lines at K 579 and 577, a green line at A. 546. and a green band 

 at \ Si6'5. These different lines will be defined by-and-by. 



The photographic spectrum, taken during this time, with an 

 hour's exposure, shows the princii>al bands of nitr<^en, as well 

 as a blue line K 436, a violet line A 405, and an ultra-violet line 

 \ 354 : these latter being more feeble than the bands of nitrogen. 



During the following hours, the green glow constantly increases, 

 the yellow lines and line X 546 increase, and the band \ 5l6'5 

 diminishes. .At the end of eight hours, the bands of nitrogen 

 have almost entirely disa|)peared in the photograph : without 

 doubt it is because the corresponding nitrogen has been absorbed 

 by the benzene. 



Seven additional hours of sparking bring the fluorescence to a 

 brilliant emerald colour, visible in broad daylight : the intensity 

 of this phenomenon, as I have already had occasion to sav, 



* Translated from C^t^wz/Zi-i fituiui, June 24, pp. 1386-1390 



