September 9, 1897] 



NATURE 



449 



Conclusion. 



In the course of this series of articles, I have referred 

 to the many points on which hght was thrown by the 

 observations made in 1893. 



It is quite obvious that the aim of those who observe 

 in India next year with the view of advancing the more 

 important problems of physics and chemistry presented 

 to us by the eclipsed sun, should work along the new 

 lines with a view of testing the soundness of the con- 

 clusions so far arrived at, and of obtaining new know- 

 ledge. I cannot, I think, more fitly close this article 

 than by giving a very brief summary of the conclusions 

 arrived at in the observations of 1893, so that my readers 

 can gather the drift of much of the work that will be 

 undertaken in 1898. 



(i) With the prismatic camera photographs may be 

 obtained with short exposures, so that the phenomena 

 can be recorded at short intervals during the eclipse. 



(2) The most intense images of the prominences are 

 produced by the H and K radiations of calcium. Those 

 depicted by the rays of hydrogen and helium are less 

 intense and do not reach to so great a height. 



(3) The forms of the prominences photographed in 

 monochromatic light (H and K) during the eclipse of 

 1893, do not differ sensibly from those photographed at 

 the same time with the coronagraph. 



(4) The undoubted spectrum of the corona, in 1893, 

 consisted of seven rings besides that due to 1474 K. 



The evidence that these belong to the corona is 

 absolutely conclusive. It is probable that they are only 

 represented by feeble lines in the Fraunhofer spectrum, 

 if present at all. 



(5) All the coronal rings recorded were most intense 

 in the brightest coronal regions near the sun's equator 

 as depicted by the coronagraph. 



(6) The strongest coronal line, 1474 K, is not repre- 

 sented in the spectrum of the chromosphere and pro- 

 minences, while H and K do not appear in the spectrum 

 of the corona, although they are the most intense radi- 

 ations in the prominences. 



(7) A comparison of the results with those obtained 

 in previous eclipses confirms the idea that 1474 K is 

 brighter at the maximum than at the minimum sun-spot 

 period. 



(8) Hydrogen rings were not photographed in the 

 coronal spectrum of 1893. 



(9) D3 was absent from the coronal spectrum of 1893, 

 and reasons are given which suggest that its recorded 

 appearance in 1882 was simply a photographic effect 

 due to the unequal sensitiveness of the isochromatic 

 plate employed. 



(10) There is distinct evidence of periodic changes 

 of the continuous spectrum of the corona. 



(11) Many lines hitherto unrecorded in the chromo- 

 sphere and prominences were photographed by the 

 prismatic cameras. 



(12) The preliminary investigation of the chemical 

 origins of the chromosphere and prominence lines 

 enables us to state generally that the chief lines are due 

 to calcium, hydrogen, helium, strontium, iron, mag- 

 nesium, manganese, barium, chromium, and aluminium. 

 None of the lines appears to be due to nickel, cobalt, 

 cadmium, tin, zinc, silicon, or carbon. 



(13) The spectraof the chromosphere and prominences 

 become more complex as the photosphere is approached. 



(14) In passing from the chromosphere to the promi- 

 nences some lines become relatively brighter, but others 

 dimmer. The same lines sometimes behave differently 

 in this respect in different prominences. 



(15) The prominences must be fed from the outer 

 parts of the solar atmosphere, since their spectra show 

 lines which are absent from the spectrum of the chromo- 

 sphere. 



(16) The absence of the Fraunhofer lines from the 

 NO. 1454, VOL. 56] 



I integrated spectra of the solar surroundings and un- 

 eclipsed photosphere shortly after totality need not 

 necessarily imply the existence of a reversing layer. 



(17) The spectrum of the base of the sun's atmosphere, 

 as recorded by the prismatic camera, contains only a 

 small number of lines as compared with the Fraunhofer 

 spectrum. Some of the strongest bright lines in the 

 spectrum of the chromosphere are not represented by 

 dark lines in the Fraunhofer spectrum, and some of the 

 most intense Fraunhofer lines were not seen bright in 

 the spectrum of the chromosphere. The so-called " re- 

 versing layer " is, therefore, incompetent to produce the 

 Fraunhofer spectrum by its absorption. 



(18) Some of the Fraunhofer lines are produced by 

 absorption taking place in the chromosphere, while 

 Others are produced by absorption at higher levels. 



(19) The eclipse work strengthens the view that 

 chemical substances are dissociated at solar temperatures. 



Norman Lockver. 



VICTOR MEYER. 

 yiCTOR MEYER was born on September 8, 1848, 

 * and died on August 8, 1897. He studied chemistry 

 at Heidelberg, under Bunsen, and at Berlin, under Baeyer. 

 His first official appointment was at Stuttgart, whence 

 he was called, in 1872, to the chair of Chemistry at 

 the Zurich Polytechnic. In 1885 he went to Gottingen, 

 and in 1889, on the retirement of Bunsen, he was 

 appointed Professor of Chemistry at Heidelberg. The 

 later years of his life were clouded by ill-health. His 

 almost abnormal mental activity allowed him no rest, and 

 he suffered greatly from insomnia. To the effects of this 

 malady on a highly sensitive nervous organisation must 

 be ascribed his tragic death in the midst of a career 

 which, brilliant though it was, gave promise of still 

 greater things in the future. 



As an investigator Victor Meyer undoubtedly stands 

 in the very front rank. In these days of specialisation it 

 is given to but few men to possess a complete mastery 

 over more than one department of a science. Meyer was 

 equally at home when dealing with the problems of 

 physical chemistry and when working out the chemistry 

 of a group of organic compounds. 



His first important investigation was that on the nitro- 

 paraffins. In 1872 he discovered nitro-ethane, and, 

 following this up with characteristic energy, had soon 

 studied several of its homologues, as well as secondary 

 and tertiary nitro-paraffins. By the action of nitrous 

 acid on these substances he obtained nitrolic acids and 

 pseudo-nitrols, and, by his study of these substances, 

 cleared up the constitution of iso-nitroso and nitroso 

 compounds. In 1882 he made the important discovery 

 that iso-nitroso compounds are formed by the action of 

 hydroxylamine on aldehydes and ketones. The generality 

 of this reaction has been of considerable importance in 

 the determination of the constitution of organic com- 

 pounds, affording a sure indication of the presence of a 

 carbonyl group. 



Meyer's discovery of the o.ximes may be regarded as 

 the foundation of our knowledge of the stereochemistry 

 of nitrogen, for in 1888, working with his pupil Auwers, 

 he showed that the two isomeric benzil dioximes then 

 known were structurally identical. It is of interest that 

 the molecular weights of these bodies were shown to be 

 identical by means of the, then little known, cryoscopic 

 method. To the further development of the stereo- 

 chemistry of nitrogen, Meyer and his pupils contributed 

 not a little. 



The discovery of thiophene in 1882 by Victor Meyer 

 was the result of a lecture experiment which failed. 

 Benzene prepared from benzoic acid was shaken with 

 strong sulphuric acid and isatin, and failed to give the 



