520 



NATURE 



\April 12, 1877 



App. Decl. of Mars. 



— 2°2 25 24 



22 38 27 .. 



22 51 22 



23 4 O .. 

 23 i6 13 .. 

 23 27 51 .. 

 23 38 47 ■■ 

 23 48 55 •• 



23 58 7 •• 



24 6 18 .. 

 24 13 23 .. 

 24 19 18 .. 



— 24 23 59 .. 



Log. distance 

 from Earth. 

 9*59247 

 9-58837 

 9-58489 



9"5820i 



9'57975 

 9-578x2 



9*57714 

 9-57678 



9*57705 

 9*57796 



9*57951 

 9-58166 



9*58443 



The opposition will take place on August 4, and Mars will be in 

 perigee on August 6 at a distance of 0-3774. The distance in 

 perigee in the present year will be 0-3767. 



The Comet 1873 II. (Tempel, July 3),— This very interest- 

 ing comet of short period will return to perihelion in 1878. The 

 elements which rest upon the widest extent of observation are 

 those of Mr. W. E. Plummer ; in his orbit the period of revolu- 

 tion is 1850-25 days, or 5-066 years, and the perihelion passage 

 in 1873 having taken place June 25-38, G.M.T., the comet, neg- 

 lecting the effect of perturbations which in the present revolution 

 is not likely to be material, will be again due in perihelion about 

 1878, July 19-5. Probably geocentric places derived from Mr. 

 Plummer's orbit, with this date for perihelion passage, will give 

 a sufficient idea of the circumstances of the next appearance, 

 and a few positions so derived are accordingly subjoined : — 



The comet, therefore, appears under conditions nearly as 

 favourable as possible for observations, the least distance of its 

 orbit from that of the earth being 0-33, at a greater radius-vector. 

 In aphelion the comet is distant from the sun 4-555, and its dis- 

 tance from the orbit of the planet Jupiter at this point (which is 

 that of nearest approach) is 0-736. Four days after perihelion 

 passage the comet approaches the orbit of Mars within 0-05, all 

 these distances being expressed in parts of the earth's mean dis- 

 tance from the sun. 



There does not appear to have been any observation of this 

 comet previous to 1873, notwithstanding its short period. It 

 could neither have been the object seen on one morning only in 

 October 1846 by Hind, nor that observed by Goldschmidt on 

 May 16, 1855, which was at first mistaken for the short-period 

 comet of De Vico (1844 I). 



In addition to the comet in question, Tempel is also the dis- 

 coverer of comet 1866 I, associated with the great November 

 meteor-shower, and comet 1867 II, which was re-observec' in 



1 873, after its orbit had undergone considerable change from a 

 near encounter with Jupiter about the preceding aphelion 

 passage. 



Ni.\v Comet. — Prof. Winnecke, the director of the Imperial 

 Observatory at Strasburg, announces his discovery of "a fine 

 bright comet, with nucleus and trace of a tail," early on the 

 morning of April 6. The following position depends upon ob- 

 servations with an annular micrometer on a 35 feet-telescope, the 

 comet being inconveniently situated for the larger instrument. 



April 5 at I5h. 53m. 39s. mean time at Strasburg, Right 

 Ascension 22h. 7m. 49-445., Declination + 14° 54' 15 -4". The 

 diurnal motion in R.A. is rather less than im., and that in Decl. 

 about I \°, both increasing. 



The dearth of comets which had prevailed since December 



1874, appears to have terminated, and we must soon hear qC the 



re-discovery of the one which bears the name of D' Arrest, and 

 has been so elaborately calculated by M. Leveau. 



[Since the above was in type the following elements, calcu- 

 lated by Herr Hartwig, have been received from Prof. Win- 

 necke : — Perihelion passage, April i8'i74i, Berlin time, longi- 

 tude of perihelion, 251° 59' 57" ; ascending node, 317° 51' i8";",§ 

 inclination, 56° 42' 42"; logarithm of perihelion distance^ 

 9-96767, motion retrograde. By these elements the comet at' 

 midnight on April 25, in R.A. 22h. 39m. and N.P.D. 42° -7, 

 will have twice the theoretical intensity of light that it had on 

 the date of discovery.] f 



CHEMICAL NOTES 

 The New Metals Ilmenium and Neptunium. — About 

 thirty years ago R. Hermann announced the discovery of a new 

 metal, ilmeniam, accompanying tantalum and niobium in various 

 minerals, and closely allied to them in its general characters. 

 Several years later he relinquished his claims to the discovery, in 

 consequence of researches by Marignac in the same field leading 

 to entirely different results. Later investigations have, however, 

 strengthened his belief in the existence of ilmenium, and in the 

 February number of Kolbe's Journal. Jur praktische Ckemie he 

 not only brings forward results 'tending to establish the individual 

 character, of ilmenium, but describes a new metal, neplunium, 

 belonging to the same group, and occurring in tantalite from 

 Haddam, Connecticut. As the quantities obtained are small, 

 the characteristic reactions limited, and as the spectral properties 

 cannot be made use of, chemists will naturally reserve their 

 opinion till confirmatory observations have been made by some 

 other well-known investigator. The following are the essential 

 results obtained by Hermann. The mineral was found to consist 

 of equal portions of columbite (ROMcgOa) and ferroilmenite 

 (R02Me02). By fusion with potassium bisulphate the hydrates 

 of the metallic oxides were separated out in the following pro- 

 portions : — 



^1^9? 32-39 



Nb^O^ 3679 



II4O7 24-52 



NpaOy 6-30 



100-00 

 The hydrates can be changed into double fluorides, and from the 

 greater solubility of potassium-neptunium fluoride, it may be 

 obtained free from tantalum and ilmenium salts but retaining a 

 sm.all quantity of the niobium salt ; these, however, on being 

 changed into niobate and neptunate of sodium may be separated 

 on account of the greater solubility of the latter. By fusion of 

 the neptunate of sodium with potassium bisulphate and treatment 

 with water, the hydrate of neptunic acid was obtained in a pure 

 condition. Neptunium may be distinguished from niobium and 

 ilmenium by its having, along wilh tantalum, the property of 

 forming an amorphous insoluble precipitate on the addition of 

 caustic soda to the boiling solution of the fluoride ; the other 

 two form crystalline and easily soluble compounds. Thft 

 very soluble character of neptunium-potassium fluoride as co: 

 pared with the corresponding tantalum salt serves to distin 

 it from that metal. The reactions with phosphorus salts 

 the inner part of the bunsen flame are the following : 

 taUc acid, colourless ; niobic acid, blue ; ilmenic acid, brown 

 neptunic acid, wine yellow. Addition of tincture of galls 

 solutions of the sodium salts gives characteristically-coloured pi 

 cipitates. The atomic weight of nep .unium, determined from ti 

 double salt 4KFI + NP2FI-.2H2O, was found to be 118. H 

 mann has also obtained ilmenium in the form of a black powi 

 by heating potassium-ilmenium fluoride with potassium chlorii 

 and potassium. 



ABSORPTION OF Hydrogen by Organic Substanci 

 UNDER THE Influence of the Silent Discharge.—: 

 Berthelot has recently found that under the effect of the di^^ 



