July 25, 1889] 



NA TURE 



307 



The barium salt o!"a new acld-rormingToxide of cobalt, CoOo, 

 corresponding to the black dioxide of manganese, MnOj, bas 

 been obtained by M. Rou-seau, and is described in the current 

 number of the Coiiiftcs lendus. It forms large black prismatic 

 crystals, and appears to be a very definite compound of the com- 

 position BaO . CoOo, and possessing some stability. The most 

 favourable method of preparing it isf as follows. A mixture of 

 15 grams of crystals of barium chloride or bromide with 5 or 

 6 grams of finely-powdered anhydrous barium oxide is heated 

 gradually to redness in a platinum crucible. The temperature 

 is then raised in a good furnace to iooo°-iioo° C, when i 

 gram of sesquioxide of cobalt, C02O3, is introduced by degrees 

 into the fused mass, and the temperature ^maintained for about 

 five hours. At the expiration of this time a ring of large black 

 prisms, exhibiting beautiful iris-coloured reflections, is formed. 

 The CI ystals are found to contain a little platinate of barium, 

 o .ving to the platinum crucible being attacked at the high tempera- 

 ture, but after elimination of this impurity the analyses agree very 

 closely with the formula BaO . CoOg. The crystals of this mono- 

 cobaltite of barium are soluble in cold concentrated hydrochloric 

 acid with evolution of heat, and dissolve likewise in nitric acid 

 with effervescence. At a higher temperature than 1100° they 

 are decomposed_with evolution of oxygen gas, the C0O2 becoming 

 reduced to a lower oxide, probably C03O4, the usual product of 

 the ignition of cobalt oxides. Hence the necessity for keeping 

 the temperature below 1100° during the preparation. If the 

 fusion be simply performed over the Bunsen lamp, another 

 cobaltite is obtained containing two molecules of CoO,. A crust 

 of crystals of this second compound, BaO.aCoOg, is formed 

 over the surface of the melt, consisting of brilliant black hexa- 

 gonal lamella:. These crystals are likewise soluble in hydro- 

 chloric acid with evolution of chlorine gas. In order to avoid the 

 formation of this di-cobaltite it is necessary to maintain the tem- 

 perature over icoo', when the neutral monocobaltite is alone 

 produced. Hence the limits of temperature during which the 

 monocob.iltite is produced are iooo°-iico''. Thus cobalt re- 

 sembles manganese in forming a dioxide, capable of liberating 

 chlorine from hydrochloric acid and combining with basic oxides 

 to form cobaltites analogous to the manganites. But this dioxide 

 of cobalt appears from its reactions to be somewhat weaker in its 

 combinations than manganese dioxide, and to form them with 

 greater difficulty, the barium cobaltites above described being as 

 yet the only ones prepared. 



The additions to the Zoological Society's Gardens during the 

 past week include two Crested Porcupines {Hystrix cristala), a 

 Desert Buzzard {Buteo desertorum), two Natal Francolines 

 {Francolinus natalcnsis i ?) from South Africa, presented by 

 Captain Henry F. Hoste, R.M.S. Trojan; a Common Wolf 

 {Canis htptis,]\xv.) from Provincia de Leon, Spain, presented by 

 Mr. \V. S. Lart ; four Violaceous Night Herons {Nycticorax 

 violaceus), a Green Bittern {Bniorides virescens), a Dominican 



Kestrel {Tinnuiiculus dominicensis), a ■ Pigeon {Cohnnba, 



sp. inc.) from St. Kitt's, W.T., presented by Dr. A. P. Boon, 

 C.M.Z.S. ; two Ocellated Mantis [Ilar/ax ocellata) from South 

 Africa, presented by Colonel J. H. Bowker, F.Z.S. ; a Wapiti 

 Deer {Cervtis canadensis ? ), a Peacock Pheasant {Polyplcctron 

 chinquis), eight Mandarin Ducks {Alx galeriadata), five 

 Summer Ducks {^¥.x sponsa), two Chiloe Wigeon {Mareca 

 chiloensis), six Chilian Pintails {Dafila spinicauda), three 

 Australian Wild Ducks {Anas superciliosa), bred in the Gardens. 



OUR ASTRONOMICAL COLUMN. 



The Binary 7 Corona: Borealis. — Prof. Celoria has 

 recently determined (^j-.';-. Nach., 2904) a new orbit for this 

 difficult binary (2 1967), which appears a decided advance upon 

 that of Dr. Doberck's, published twelve years ago. A consider- 



able uncertainty still attaches, however, to the elements, although 

 the star has now been under observation for sixty-three year?, 

 and has been watched through nearly three-fourths of a revolu- 

 tion. This is due partly to the circumstance that the orbit is 

 presented to us nearly in profile, and partly to the closeness cf 

 the two components. The measures in both elements, therefore, 

 have been difficult to make, and have often been very discordant. 

 Thus some recent position-angles by Engelmann i^how a sys-^ 

 tematic difference of 30"" or more as compared with measures 

 made at about the same epoch by Schiaparelli and Perrotin. 

 The companion passed its primary on the north side about 1836, 

 reappearing in 1840 on the preceding side. It re-passed the 

 principal star on the south about 1878, and is now again on the 

 following side. Celoria's new elements compare with Doberck's 

 as follows : — • 



Doberck. 

 T = 184370 

 9> — 1 10' 24' 



A = 23?° 30 



7 = «5° 12' 



c = 0-350 



a = o"7o 



P ~ 95 '50 years. 



Celori?. 

 1840-508 

 113' '47 y 



250-68 



81-66 

 034827 

 o"-63ro3 

 85 276 years. 



Eclipses and Transits in Future Years. — The Rev. S. 

 J. Johnson, author of " EclipFes Past and Future," and well 

 known as a calculator of eclipses, presented a large manuscript 

 volume to the Royal Astronomical Society a few months ago 

 containing projections and diagrams of eclipses from the year 

 A.D. 538 to the year 2500. He has now published in a little 

 pamphlet the dates of all the eclipses, both of sun and moon, 

 visible in England from 1700 to 20co, with the solar eclipses for 

 the two follov/ing centuries, and the larger solar eclipses up to 

 2500. The transits of Mercury and Venus are also included, 

 of Venus up to 2500, and of Mercury to 2000. 



The twentieth century is distinguished by three years in each 

 of which seven eclipses take place. Of these, Mr. Johnson 

 notices two, 191 7 and 1935, the latter being particularly note- 

 worthy as showing five solar eclipses, but does not mention the 

 third case, 1985, though calling attention to the rare occurrence 

 of three total eclipses of the moon which fall that year. 



The little pamphlet, which is intended as a kind of supplement 

 to the author's larger work, "Eclipses Past and Future," is 

 illustrated by four pages of diagrams showing the greatest 

 phases of the eclipses up to 1949, as seen from London. The 

 diagrams are nowhere explained, and no indication is supplied 

 as to which are solar and which lunar eclipses. It appears that 

 circles on which the eclipsed portion is shown by deep shading,. 

 and which are surrounded by a ring of shade, stand for solar 

 eclipses, the plain circles for lunar eclipses. 



The White Spot on Saturn's Ring.— M. Terby, who 

 still strongly contends for the reality of the bright white spot 

 next the shadow of the planet on Saturn's ring, quotes, in the 

 Astronomische Nachrichtcn, No. 2910, an observation of Ceraski's 

 made in 1884, as showing that it is not a mere effect of contrast 

 with the shadow. M. Ceraski, on November i, 1884, noticed 

 a bright white spot on the ring where it touched the planet in a 

 similar position to M. Terby's spot, but the shadow of the 

 planet fell at that time on the other portion of the ring, so that 

 the spot could not be accounted for by contrast. 



Comet 1889 c (Barnard, June 23). — The following ephe- 

 meris for this object is by Dr. R. Spitaler {Asir. Nach.. 

 No. 2909) : — 



For Berlin Midnight. 

 1889. R.A. Decl. Log A. Bright- 



h. m. f. o / ness. 



July 27 ... 3 51 I ... 49 27-4 N. ... 0-1341 ... 0-55 



31 ... 4 6 14 ... 49 47-6 ... o*i4i6 ... 0-50 



Aug. 4 ... 4 20 35 ... 50 0-3 ... 0-1486 ... 0-46 



8 ... 4 34 o ... 50 7-0 ... 0-1549 ... 0-43 



12 ... 4 46 29 ... 50 8-5 ... 0-1606 ... 0-40 



16 ... 4 58 I ... 50 6-0 ... 0-1656 ... o*37 



20 



5 8 37 ... 50 0-5 N, ... 0-1699 ••• 0-34 



ASTRONOMICAL PHENOMENA FOR THE 

 WEEK 1889 JULY iZ— AUGUST 3. 



/"C'OR the reckoning of time the civil day, commencing ab 

 ^ -^ Greenwich mean midnight, counting the hours on to 24, 

 is here employed.) 



