April 14, 1892] 



NATURE 



569 



The anhydrdus sulphates of zinc, copper, nickel, and cobalt 

 have been obtained in well-developed crystals by M. Kiobb, who 

 describes his experiments in the current numloer of the Comptes 

 rendus. It was first observed that when a small quantity of the 

 ordinary hydrated sulphate of cobalt was allowed to fall into 

 fused sulphate of ammonia it immediately dissolved, imparting a 

 deep blue colour to the liquid, and when the heating was con- 

 tinued in such a manner that the ammonium sulphate slowly 

 volatilized away, the walls of the crucible were found to be covered 

 with small red crystals. Upon analysis these crystals proved to 

 be those of anhydrous cobalt sulphate. Similar experiments 

 with the hydrated sulphates of zinc, copper, and nickel succeeded 

 equally well, and it was found to be immaterial whether the 

 hydrated salts with five, six, or seven molecules of water, or the 

 amorphous anhydrous silts obtained by ignition, were employed. 

 The best mode of operating in order to obtain good crystals is 

 briefly as follows. A quantity of ammonium sulphate is placed 

 in an ordinary porcelain crucible ; over this is then laid an inti- 

 mate mixture of ammonium sulphate with one-third its weight of 

 the metallic sulphate required. The crucible, covered by its lid, 

 is then inclosed together with a packing of sand within a Hessian 

 crucible, which is afterwards placed in a mufile furnace and heated 

 until the sulphate of ammonia has all escaped. The heating 

 should then be at once discontinued in order to prevent decom- 

 position of the metallic sulphate. After cooling, if the heating 

 has been carefully conducted, the residual metallic sulphate is 

 found to be crystalline throughout, and to consist largely of 

 single well -formed crystals. The result is particularly good in 

 the case of zinc sulphate. If quantities of about twenty grams 

 of anhydrous zinc sulphate are employed, colourless octahedrons 

 two and a half millimetres long may be obtained. These crystals 

 only dissolve with extreme slowness in cold water, but are much 

 more rapidly dissolved upon warming. Sulphate of copper 

 treated in a similar manner yields prismatic needles of the an- 

 hydrous salt. These crystals present a pale grey appearance, but 

 on being left exposed to the air for a few days they assume first 

 a green tint and subsequently pass over to the ordinary penta- 

 hydrated blue salt. Unlike the crystals of anhydrous zinc 

 sulphate, they are rapidly dissolved by cold water, forming the 

 usual blue solution. The crystals of anhydrous sulphate of 

 cobalt prepared in like manner consist of brilliant red octa- 

 hedrons, which are apparently unaltered by exposure to the air, 

 and which are only slightly attacked by water even when boiling. 

 Still more remarkable are the green crystals of anhydrous nickel 

 sulphate obtained by the above mode of preparation, for these 

 crystals, so unlike the readily soluble hydrated sulphate, are prac- 

 tically insoluble I'oth in cold and boiling water. This last in- 

 stance affords a striking example of the influence of water of 

 crystallization upon the solubility of a salt. 



The additions to the Zoological Society's Gardens during the 

 past week include an Entellus ^lonVt^ {Senmopithcitis entellus S ) 

 from India, prt-sented by Dr. Wm. Eamesand Dr. Earle, R.N.; 



a Owl {Pseudoscops grammicus) from Jamaica, presented 



by the Trustees of the Jamaica Institute ; a Green Conure 

 {Conurus pavua) from Trinidad, presented by Mrs. Hill; two 

 Sharp-nosed Crocodiles {Crocodilus acutus) from Central 

 America, presented by Sir Henry Arthur Blake, K.C.M.G. ; 

 two Common Vipers ( Vipera berus), British, presented by Mr. 

 A. Cotton, F.Z.S; an Orange- winged Amazon {Chrysotis 

 amazonica) ; two Mississippi Alligators {Alligator mississip- 

 piensis) from South America, a Mantchurian Crossoptilon 

 (Crossoptilon mantchuricum) from Northern China, four Spiny- 

 tailed Mastigures {(/romastix acanthinurus) from North 

 Africa, deposited ; a Slow Loris {Nycticebus tardigradus) from 

 Borneo, two Bar-breasted Finches {Munia nisoria) from Java, 

 two Mute Swans (Cygnus olor), European, purchased ; an Angora 

 Goat {Capra hircus van), bom in the Gardens. 



ND. I 172, VOL. 45] 



OUR ASTRONOMICAL COLUMN. 

 Observations of the Spectrum of Nova Aurig.^.— Dr. 

 Henry Crew, in Astronomy and Astro- Physics for Ma>ch, gives 

 a general description of the visible spectrum of Nova Aurigae on 

 February lo and ir, observed by him with a spectroscope 

 attached to the 36 inch of the Lick Observatory. The positions 

 of the following lines were determined by direct comparison 

 with the lunar spectrum and the spark spectra of hydrogen and 

 magnesium : — 



N .. of 



line. 



I 



Wave- 

 length. 

 65658 



Description. 

 Probably C ; very broad and bright in 



prism ; not seen in grating. 

 Faint, broad, diffuse. 

 Not quite so bright as 2, but broader ; 

 both 2 and 3 may be bright only in 

 comparison with neighbouring ab- 

 sorption bands. 

 Yellow line, just below D. 

 TThree very faint lines ; difficult to say 

 J whether they are really bright lines 

 j or simply bright regions bounded by 

 V. dark spaces. 

 Much more brilliant than any of the pre- 

 ceding ; quite broad ; much sharper 

 on the upper side than the lower ; 

 nearly coincides with b^ The most 

 brilliant part of the continuous spec- 

 trum is terminated abruptly by this 

 line. 

 Of about the same brilliancy as 8, and, 



like it, sharper on the upper side. 

 About half as bright as 9. 

 Probably F ; not less than 6 tenth- 

 metres in width. 

 Hy ? Wide and difficult to see. 

 A curve, showing the intensities of the lines as seen with a 

 prism, accompanies this description. Prof. Young has deter- 

 mined the positions of twelve bright lines in the Nova spec- 

 trum {Astronomical Journal, No. 258). The wave-lengths are 

 as follow: 4340 (H7), 449, 4861 (F), 4922, 5015, 5165, 

 5260, 5304, 559, 590 (D?), 632, 6563(C). A faint line was 

 also glimpsed below C, and another — probably h — above G. 

 The lines at 4922 an 1 5015 are believed not to be nebular lines. 

 Those at 559 and 632 are possibly coincident with the two 

 principal hnes in the aurora spectrum, 



Denning's Comet (b \%()2).— Edinburgh Circular '^o. 25 

 contains the foUo^ring elements and ephemeris of Denning's 

 comet, computed by Dr. R. Schorr : — 



Elements. 

 T := 1892 May 613922 Berlin M.T. 



■K- Q, - 126 39 177 



a = 252 55 138 



i = 89 49 45-1 

 log ^ = o 298920 



Ephemeris for Berlin Midnight. 



6321 

 6209 



5898 



5265 

 5254 

 5216 



51671 



5009 



4920 

 4861 -6 



4352 



1892. 

 April 15 

 » 19 



May 



23 •• 



27 .. 



I .. 



5 •• 



9 •• 



13 •• 



17 .. 



21 .. 



25 •• 



29 .. 



R.A. 



h. m. s. 

 I 29 2 



1 4952 



2 9 26 

 22743 



2 4MS 



3 037 



3 1523 

 329 7 

 34155 

 35352 



4 5 3 

 41532 



Decl. 



+ 59 47-0 

 •• 59 II 4 

 .. 58 29-1 

 •• 5741-4 

 •• 56 495 

 • • 55 54-2 

 •• 54566 

 •• 53 573 

 .. 52 567 

 •• 51 55 4 

 •• 50538 



-J- 49 520 



Log r. 



0'3024 ., 



0-3012 .. 



0-3002 .. 



0-2995 - 



0-2991 .. 



o 2989 .. 



02990 .. 



o 2994 .. 



03000 .. 



03008 .. 



o 3020 .. 



03034 •• 



Log A. 

 0-3989 . 

 0-4041 . 

 04095 . 

 0-4149 . 

 0-4204 . 

 0-4258 . 

 04311 . 

 0-4362 . 

 04411 . 

 04458 . 

 0-4502 . 

 04543 • 



Bright- 

 ness. 

 .. 0-95 

 .. 0-93 

 .. 0-91 

 .. 0-89 

 .. 0-87 

 .. 0-85 

 .. 083 



.. o 8i 

 .. 079 

 .. 0-77 

 .. 0-75 

 .. 072 



The brightness at the time of discovery is taken as unity. 



The comet passed about half a degree north of 7 Cassiopeise 

 on April 8, and is moving towards Perseus. 



Comet Swift. 1892 — The following are places for this 

 week for I2h. Berlin mean time : — 



