Jan. 23, 1890] 



NATURE 



285 



benzene. It is curious that when pure benzene is allowed to 

 react upon pure SeC^, the latter body undergoes precisely the 

 same decomposition as when heated to 360°, the liberated 

 chlorine reacting with the benzene to form several chlor- 

 benzenes and all the selenium remaining in the form of 

 SegClj. If, however, the benzene and selenium tetrachloride 

 are brought together in presence of that most useful of inter- 

 mediate reagents, aluminium chloride, quite a different series of 

 changes occur. On treating the mixture with water, and separat- 

 ing and distilling the oil obtained, three distinct fractions may 

 be collected The first, which passes over at 131°-! 33°, consists 

 of monochlor benzene, CgHr.Cl. The second, distilling at 227°- 

 228" under a pressure of only a few millimetres of mercury, con- 

 sists of phenyl selenide, (C(jH5)2Se, corresponding j to phenyl 

 sulphide, (€5115)28, and phenyl oxide, (CeH5)20. It is a yellow 

 oil of sp. gr. I '45 at I9°"6. The third fraction, boiling between 

 245° and 250° under the same reduced pressure, consists of 

 another new compound of the composition Se2(C(jHp,);jCeH4Cl. 

 This substance is a red oil of sp. gr. i'55 at I9°'6. On allowing 

 this red oil to stand it deposits yellow crystals of a compound of 

 powerful odour, which may be obtained recrystallized from 

 alcohol in long rhombic prisms. On analysis this substance 

 turns out to be seleno-phenol, CgHgSeH, analagous to thiophenol 

 and mercaptan, both of evil odour. Like all the hitherto in- 

 vestigated mercaptans, its alcoholic solution readily reacts with 

 salts of mercury and silver. Analysis of the silver salt leads to 

 the formula CgHsSeAg. The reactions by which phenyl selenide 

 and seleno-phenol are respectively produced are believed by M, 

 Chabrie to be as follows : — • 



2CgH6 + SeCl4 = (C6H5)2Se -f- 2HCI + Clg, 

 CgHg -»- SeCl^ = CgHjSeH -I- 2CI2. 



The additions to the Zoological Society's Gardens during the 

 past week include a Black-headed Gull {Lartis ridibundtis), 

 British, presented by Mr. E. Hart, F.Z.S. ; a Chinese Jay 

 Thrush {Garrulax chinensis) from China, presented by Sir 

 Harry B. Lumsden, C.B., K.C.S.I., F.Z.S. ; a King Parakeet 

 {Aprosmictus scaptilatus i ) from Australia, presented by the 

 Rev. A. J. P. Matthews, F.L.S. ; a Peregrine Falcon {Fako 

 ptregrinus) from Scotland, presented by Mr. Geo. W. Landels ; 

 a Vulturine Eagle {Aquila verreauxi), a Jackal Buzzard {Bnteo 

 jcuat), a White necked Raven {Corvultur albicollis) from South 

 Africa, presented by Mr. Marshall ; a Pigmy Cormorant {Phala- 

 crocorax africanus), a Moorhen {Gallinula chloropus), two 

 Shining Weaver Birds {Hypochera nitens), four Black-bellied 

 Weaver Birds {Euplectes afer 2 <J 2 9 ), two Abyssinian Weaver 

 Birds {Ploceus ahyssinicus 6 6), four Red-beaked W^eaver Birds 

 (Quelea sanguinirostris 26 2 ? ), four Cutthroat Finches 

 {Atnadina fasciata 1 6 "i 'i), four Orange- cheeked Waxbills 

 {Eslrelda melpoda), a Paradise Whydah Bird ( Vidua paradisea 6 ) 

 from West Africa, an Indian Silver-Bill {Munia malabarica) from 

 India, two Cardinal Grosbeaks {Cardinalis virginianus 6 6) 

 an Indigo Bird {Cyanospiza cyanea 6 ) from North America, 

 purchased. 



OUR ASTRONOMICAL COLUMN. 

 Objects for the Spectroscope. 

 Sidereal Time at Greenwich at 10 p.m. on January 23 = 6h 

 12m. 44s. 



Remarks. 



(i) The General Catalogue description of this nebula is as 

 follows: "Planetary nebula; pretty bright, very small, very 

 little extended." So far as I know, the spectrum has not yet 

 been recorded, but if it is of the same nature as other planetary 

 nebulae, bright lines may be expected. The character of the 

 chief line, near A. 500, if visible, should be particularly noted. 



(2) Duner classes this with stars of Group II., but states that 

 the type of spectrum is a little uncertain. He notes, however, 

 that the bands 2, 3, and 7 are visible, so there seems to be no 

 reasonable doubt about the type. The probability is that it is 

 either an early or late star of the group, in which case we should 

 not expect to find all the bands fully developed. The star has 

 been provisionally placed in species 2 of the subdivision of the 

 group, but further observations are at once suggested to deter- 

 mine whether this is right or wrong. If right, the bright flutings 

 of carbon should be fairly prominent, as it is probably due to the 

 masking effects of these flutings that some of the dark bands are 

 absent. The carbon flutings near5i7 and 474, seen in the spectrum 

 of a bunsen or spirit-lamp flame, should therefore be particularly 

 looked for. It is possible, too, that in the earlier stars of the 

 group the hydrogen lines may appear bright, as the swarms are 

 only a little more condensed than those constituting stars with 

 bright lines, so that the interspacial radiation may more thatv 

 balance the absorption. 



(3) According to the observations of Konkoly, this is a good 

 example of stars of the solar type. The usual observations, as 

 to whether the star belongs to Group III. or to Group V., are 

 required. 



(4) A star of Group IV. (Gothard). The main point to be 

 noted iu stars of this class is the relative intensities of the lines- 

 of hydrogen and those of iron, magnesium, and sodium, for the 

 purpose of arranging them in a line of temperature. If possible, 

 the criterion lines which indicate increasing or .decreasing tem- 

 perature should also be noted, as in the stars which have 

 hitherto been classed as of the solar type. 



(5) This is a star of Group VI., showing the usual carbon, 

 flutings and the subsidiary bands 4 and 5 (Duner). In some 

 stars of the group of smaller magnitude, a greater number of 

 secondary bands have been noted, and it seems possible, there- 

 fore, that 74 Schj. may not have been observed under the most 

 favourable conditions. Further confirmatory observations are 

 therefore necessary before conclusions as to the specific differ- 

 ences between the different stars of the group can safely be 

 drawn. 



(6) The spectrum of this variable has not yet been recorded. 

 The period is 3057 days, and the range from 8'2-lo'6 at 

 maximum to < 13 ;at minimum (Gore). The maximum occurs, 

 on January 23. 



(7) This variable star has a period of 244*5 days, and ranges 

 from 7-87 at maximum to •< 13 at minimum. The spectrum, 

 is of the Group II. type, and the range of variability is such 

 that the appearance of bright lines at maximum may be ex- 

 pected, as in R Leonis, &c., observed by Mr. Espin. The 

 maximum occurs on January 25. A. Fowler. 



The Cluster G.C. 1420 and the Nebula N.G.C. 2237. 

 — Dr. Lewis Swift, in the Sidereal Messenger for January 1890, 

 calls attention to a wonderful nebulous ring entirely surrounding 

 this cluster. The ring was discovered by Prof. Barnard last 

 year {Astr. Nach., 2918), and its average outer diameter esti- 

 mated as not less than 40', so that in comparison the ring nebula 

 in Lyra is a pygmy. Although Dr. Swift discovered, in 1865, a 

 large diffused nebula north-preceding the star-cluster G.C. 1420, 

 his attention was first directed to the ring structure by Prof. 

 Barnard in January 1889. 



The nebula N.G.C. 223713 in the constellation Monoceros j; 

 its position is R.A. 6h. 24m. 48s., Decl. -i- 5° 8' ; hence it will 

 soon be favourably situated for observation, and Dr. Swift hopes 

 that Mr. Isaac Roberts will be induced to photograph it, as a 

 change both in brightness and form is suspected. 



On the Spectrum of C Urs^ Majoris. — An examination 

 of seventy photographs of the spectrum of this star, taken on as 

 many different nights at Harvard College, and beginning on 

 March 27, 1887, has led Prof. Pickering to conclude that the 

 K line is double at intervals of 52 days, and that, for several 

 days before and after it is seen to be double in the photo- 

 graphs, it presents a hazy appearance. From the period 

 assigned, it was predicted that the line should be double 

 on December 8, 1889, and January 30, 1890, and the duplicity 



