6 3 6 



NATURE 



[Oct. 26, 1882 



At iSh. Greenwich M.T. 

 R.A. N. P.D. Lo». distance from 



h. m. „ Earth. Sun. 



Nov. 2 ... 9 527 ... no 23 ... 0-1700 ... 0-1509 



6 ... 9 45-8 ... in 47 ... 0-1716 ... 0-1749 



10 ... 9 383 ... 113 9 ... 0-1728 ... 0-1970 



14 ... 9 301 ... 114 27 ... 01739 ••• 0-2176 



18 ... 9 2i - i ... 115 40 ... 01751 ... 0-2368 



22 ... 9 11-3 ... 116 47 ... 0-1766 ... 0-2549 



At the time we write a sufficient number of observations before 

 perihelion passage to allow of a reliable determination of the 

 orbit prior to the close approach to the sun, is not available. 



By the way it strikes us it is about time that M. Crul's name 

 was disassociated fro 11 this comet; if personal names are to 

 be attached to naked-eye comets, a practice which to say the 

 least, is inconvenient, Mr. Finlay, so far as is known at present, 

 has the prior claim. The system gener.-lly adopted for some 

 years, of assigning letters, a, b, c, &c, to comets discovered in 

 a particular year, until their order of perihelion passage is defi- 

 nitely known, was, we think, an advantageous one, and its 

 discontinuance in some quarters is a retrograde step. 



Comet 1882 c (Barnard, September 10). — From the first 

 observation at Harvard College on September 14, and observa- 

 tions by Prof. Millosevicb, at the Collegio Romano in Rome, on 

 September 22 and October 7, Mr. Hind has calculated the 

 following elements of this comet : — 



Perihelion passage 1S82, November 13-0367 G.M.T. 



Longitude of perihelion 354 47-6 



,, ascending node 249 8'9 



Inclination S3 43'I 



Logarithm of perihelion distance ... 9'9799S 

 Motion — retrograde. 

 From these elements it appears that the comet will be observ- 

 able in the southern hemisphere for some weeks after it descends 

 below the horizon in Europe. At perihelion passage on Novem- 

 ber 13, its ri^ht ascension will be about 199°4, with 66i° south 

 declination, which places it near 7) in the constellation Musca ; 

 on December 10 it will be situate between the stars y and 17 in 

 Ara, with 58 declination, and an intensity of light one-third 

 greater than at the first Harvard observation, and on January 9 

 its place will be near c Telescopii, with one-half the intensity 

 of light of September 14. 



Pons' Comet of 1S12. — MM. Schulhof and Bossert have 

 published a continuation of their extensive ephemerides to facili- 

 tate the search for this comet from October 2S to February 4, 

 and for equal intervals of true anomaly from -97°3o'to +82 

 30'. By their new and complete discussion of the observations, 

 including a series by Blanpain at Marseilles, which they disco- 

 vered in the original, and which tbey consider the best of all, 

 the most probable elements in 1812 were found to be as 

 follows : — 



Perihelion passage, 1S12, September 15-33210 Paris M.T. 



Longitude of perihelion 



,, ascending node ... 



Inclination 



Excentricity 



Logarithm of perihelion distance 



92 19 48-2 1 Mean 

 253 o 43-7 \ Equinox, 



73 57 35-8 1 '812° 

 0-9555842 

 9-8904903 



The corresponding period is 73-18 years, but the probable 

 error of this period of revolution is ± 4-5 years. Notwith- 

 standing this large amount of uncertainty, MM. Schulhof and 

 Bossert have calculated the effect of the action of the planets 

 Jupiter, Saturn, Uranus, and Neptune during the actual revolu- 

 tion, and find the most likely epoch of the next perihelion 

 passage to be 1884, September 3-65, M.T. at Patis. 



The Transit of Venus.— Mr. Marth, who has charge of 

 the proposed station at Montague Road, Cape Colony, left for 

 Cape I own in Messrs. Currie and Co.'s mail steamship Conway 

 Castle on the 13th inst., and Mr. Talmage, of Mr. J. Gurney 

 Barclay's observatory at Leyton, proceeded in the R. M. steam- 

 ship Nile on the 17th for Barbados, with Lieut. Thomson, R.A., 

 as his colleague. Mr. J. I'lummer, in charge of Col. Tomline's 

 observatory at Orwell Park, Ipswich, with Lieut. Neate, R.N., 

 have also left for New York, on their way to Bermuda. All 

 the British expeditions are therefore 01 route. 



Brazil will furnish four stations, with similar instrumental 

 equipment, including equatorials of 6 inches aperture. M. 



Cruls proceeds to a point in the Straits of Magellan, and Baron 

 de Jeffe, of the Brazilian Navy, to St. Thomas. The other 

 stations will be Pernambuco, and the Imperial Observatory at 

 Rio Janeiro. M. Faye, who made a communication to the Paris 

 Academy of Sciences on the 16th inst., in the name of the 

 Emperor of Brazil, who takes a lively personal interest in his 

 observatory, mentions that it is in contemplation to effect achro> 

 nonetric connection of the st.iti >n in the Straits of Magelhn 

 with Montevideo, an important undertaking, as viewed with 

 reference to the telegraphic determination which the Board of 

 Longitudes is about to execute across the American continent, 

 from Montevideo or Buenos Ayres, to Santiago and Lima. 



A SPECTROSCOPIC STUD Y OF CHLOROPH YLL » 

 'THE study of chlorophyll has great fascination ; it also has its 

 •*• difficulties. We did not propose adding to the many 

 elaborate attempts to isolate and purify this body ; but the beauty 

 and definite character of the spectrum which it gives induced 

 us to try whether some insight into its character and constitution 

 could not be obtained from the study of the spectroscopic 

 changes which it can be made to undergo ; and as one of us has 

 already shown that in the case of the cobalt salts, the spectro- 

 scope enables us to follow many chemical chantres, we thought 

 that it might be possible to interpret the spectroscopic changes 

 of chlorophyll, and so gain some knowledge of the properties 

 and nature of this body. 



The extraction of the green colouring matter from leaves was 

 effected in most cases by breaking up the leaves in a mortar with 

 a mixture of two parts of alcohol and one of ether. The colour 

 of the liquid thus obtained is of a dark green, varying in shade 

 according to the nature of the leaves used, and the solution 

 always has the well-known red fluorescence. This liquid, when 

 examined spectroscopically, gives what is known as the chloro- 

 phyll spectrum. According to Krauss, it consists of seven 

 bands ; the three at the most refrangible end of the spectrum 

 are difficult, as Krauss says, to observe, and with our source of 

 light, a gas-flame, we could see in an ordinary chlorophyll solu- 

 tion little or nothing of them ; but under special circumstances, 

 which will be described further on, the least refrangible of the 

 three becomes very visible. We have confined our observations 

 principally to the four least refrangible bands. Other solvent-, 

 such as chloroform, disulphide of carbon, benzene, &c, were 

 used occasionally; they give a similar spectrum, but in most 

 cases they do not dissolve the colouring matter so readily as 

 alcohol and ether do. The ethereal solution appears always to 

 give a clearer and more brilliant spectrum than the alcoholic 

 solution. Fig. I shows the spectrum of the solution obtained as 

 above described from the majority of the leaves we have exa- 

 mined. 



Among common outdoor plants, the vine and the Virginian 

 creeper may be cited as apparent exceptions, giving a different 

 spectrum. (Fig. 2.) The second band in this case has moved 

 towards the more refrangible end of the spectrum, the band from 

 589 to 573 has disappeared, and now there is a very marked 

 band from 545 to 532. The cause of this change in the spec- 

 trum we shall explain further on. 



Fig. I then, as far as it goes, represents the spectrum given by 

 the alcohol and ether extract of most leaves. It is important at 

 once to give a definite meaning to the term chlorophyll, and we 

 would therefore state that we mean by it the body or bodies 

 capable of giving this particular spectrum, and of course we 

 found our conclusions on the assumption that a particular 

 absorption-spectrum is a complete identification of a substance. 



As is well known, the exact position of these bands alters 

 with the solvent used ; in all cases, w hen no mention is made 

 to the contrary, a mixture of alcohol and ether is the solvent we 

 have used. Apparently the statement that the higher the 

 specific gravity of the solvent, the nearer are the bands to the 

 red end of the spectrum, is not in all cases true, for we find that 

 the chlorophyll bands are nearer to the red in carbon disulphide 

 than in chloroform. All our observations have been made with a 

 Dasaga's spectroscope having a single heavy glass prism, and 

 the position of the bands is given in millionths of a meter, 

 reduced from the observations by graphical interpolation. 

 Capt. Abney has also been kind enough to take photograph- of 

 the different spectra, and these agree with our eye observations. 

 They also prove that there are no bands in the ultra-red. 



The first point we would note with regard to chlorophyll is 

 1 By W. J. Fussdl, Ph.D.. F.R.S.. and W. Lapraik, F C.S. 



