November 22, 1894] 



NA rURE 



8=; 



tion of an open cylinder is a new evidence of its disruptive 

 force. In the year 18S4 Prof. Meyer, in conjunction with Prof. 

 Seubert, showed that the detonating mixture of acetylene and 

 oxygen ignites at a lower pressure than all other combustible 

 gases, a pressure equal to thirty-two millimetres of mercury 

 being sufficient to enable it to explode, while hydrogen and 

 oxygen require a pressure of at least one hundred millimetres, 

 and carbon monoxide and oxygen over two hundred millimetres. 

 This, however, is not sufficient to account for the enormous 

 pressure developed in an open cylinder. A^oreover, it cannot 

 be due to the more rr^pid rate of propagation of the explosion, 

 for M. Berthelot and Prof. Dixon' have independently found 

 that the rapidity in the case of the acetylene detonating mixture 

 is but slightly greater than in the mixtures of oxygen with ethylene 

 or marsh gas, and much less than in the case of a mixture of 

 hydrogen and oxygen. Prof. Meyer suggests that the smaller 

 amount of hydrogen contained in acetylene than the other hydro- 

 carbons, resulting in the production of less water vapour and 

 relatively more carbon dioxide, together with the fact that the 

 theoretical temperature of the combustion calculated from exist- 

 ing thermal data, is extremely high in the case of acetylene, may 

 afford some explanation of the extraordinary energy developed 

 during the explosion of the latter. 



A PURE white di-sulphide of tin has been obtained by Dr. 

 Schmidt in the laboratory of the Berlin University, which is 

 further distinguished by the property of being readily soluble in 

 ammonium carbonate. It may easily be pre.>ared as follows : 

 Metallic tin is first dissolved in hydrochloric acid, and the 

 stannous chloride oxidised by digestion with nitric acid to 

 stannic chloride, and the excess of acid largely removed by 

 evaporation. After dilution with water ths tin is precipitated 

 as the ordinary yellow sulphide by sulphuretted hydrogen. The 

 washed precipitate is next freed from traces of arsenic by solu- 

 tion in concentrated hydrochloric acid and reprecipitating 

 the diluted and filtered solution with sulphuretted hydrogen. 

 The well-washed yellow precipitate is then digested with a 

 large excess of ammonium hydrate for some days at the 

 ordinary temperature, when the whole of it eventually dissolves 

 except small traces of the black sulphides of lead and bismuth. 

 Upon diluting the clear ammoniacal solution and neutralising it 

 with dilute sulphuric acid, an almost perfectly while precioitale 

 is obtained. This precipitate dissolves at once almost com- 

 pletely in ammonium carbonate, and upon again neutralising 

 with dilute sulphuric acid the disulphide precipitated is pure 

 white. This new form of stannic sulphide is very voluminous, 

 and it apparently owes its absence of colour and greater bulk 

 to the fact that stannic sulphide here exists either in a difterent 

 state of molecular aggregation or of hydration. It is signifi- 

 cant that upon drying it becomes amber-yellow and loses its 

 property of dissolving in ammonium carbonate. 



The additions to the Zoological Society's Gardens during the 

 past week include a Lesser White-nosed Monkey {Ccrcopithecns 

 pttaurista), a Pel's Owl (Scolopcliti pelt), an Angolan Vulture 

 {Gypohitrax angolensis), a Black Kite {A/i/vm migrans}, a 

 Buzzard (Buleo, sp. inc. ) from West Africa, presented by Mr. 



C. B. Mitford ; two Baboons {Cynoctphaliis, sp. inc.) from 



East Africa, presented by Mr. Charles Palmer ; a Chilian Sea 

 Eagle (Geratioitliis mslanoleuius) from South America, pre- 

 j sented by the Rev. Fred L. Curne ; two Bronze-winged 

 I Pigeons {/Viaps chalcoptcra) from .\ustralia, presented by Mrs. 

 Amy Jones ; ten Surinam Toads (/'/pra amcricaiia) from 

 Surinam, presented by Mr. F. E. Blaauw ; five Three-streaked 

 Euprepes (Eiiprefres triviltalus) from South Africa, presented 

 by Mr. J. E. Matcham : a Muscat Gazelle {GazeHa mtiscalensis) 

 from Muscat, an Echnida {Eckiiida /lyilrix) from New South 

 Wales, deposited; four Lapwings {Vantllin crislalus), British, 

 purchased. 



WO. f3o8, VOL. 51] 



OUR ASTRONOMICAL COLUMN. 



Observations 01 the Transit of Mercury.— Several 

 French astronomers made preparations for observing the recent 

 transit of Mercury across the sun, but the weather conditions on 

 the other side of the Channel were just as unfavourable as they 

 were here. The current Complss renclus contains a brief note on 

 the transit, by M. Trouvelot. This observer saw Mercury pro- 

 jected upon the sun at 4h, 12m. The planet was sharply defined, 

 and appeared as a circular, imensely black, spot on the luminous 

 background of the sun. In spile of careful observation, M. 

 Trouvelot was unable to detect any trace of a luminous ring 

 such as he observed round the planet during the transit 01 

 187S. The unfavourable conditions of observation, however, 

 are sufficient to explain the absence of the phenomenon. 



Dr. Janssen also contributes a note on the transit of Mercur)' 

 to Comptes retuliis. He intended to look particularly for the 

 "black-drop" observed during the transit of Venus in 1874, but 

 clouds prevented the observation. 



Ephe.meris ok E.ncke's Comet.— The following positions 

 for Encke's Comet duiing this year are from an ephemeris given 

 by Dr. O. Backlund in the Astronomiiche Naclirichlen, No. 

 3263. The comet will pass perihelion on February 4, 1895. 

 In the year 1S62, its perihelion passage occurred on February 6. 



Ephemirii for oh. Bcrliit Mian Time, 

 i8y4. R..^ app. Decl. app. 



h. ni. s. . , /, 



Nov. 22 ... 223554-79 ... -f 9" 651-0 



24 ■•■ 33 2502 • • 8 40 53-6 



„ 26 ... 31 793 8 15 59-1 



>. 28 ... 29 3-11 7 52 9-1 



3° ■•■ 27 9-98 ... 7 29 240 



Dec. 2 ... 25 28-18 ... 7 7 43-2 



4 ■•■ 23 57-09 ... 6 47 5-3 



,, 6 ... 22 3602 ... 6 27 27-9 



8 ... 21 24-29 ... 6 8 485 



,, 10 ... 20 21-19 ••- 5 51 36 



„ 12 ... 19 25-94 ... 5 34 8-3 



„ 14 ... 18 37-75 ... 5 17 577 



„ l6 ... 17 5577 ... 5 2 257 



„ 18 ... 17 19-11 ... 4 47 25-7 



,, 20 ... 16 4682 ... 4 32 506 



,, 22 ... 16 17-82 ... 4 iS 320 



,, 24 ... 15 50-85 ... 4 4 190 



,, 26 ... 15 24-59 ... 3 49 592 



„ 28 ... 14 57-30 ... 3 35 182 



„ 30 ... 22 14 2709 ... -^ 3 19 583 



Recent Observations of Jupiter.- Prof. E. E. Barnard 

 communicates to this month's Astronomy and Astro-Physics an 

 account of his recent observations of the great red spot and other 

 markings on Jupiter. The following points with regard to these 

 features are of interest to observers : " The surface of Jupiter 

 is very strongly marked, during this opposition, by two" broad 

 reddish belts, one on each side of the equator, and a bi-oad white 

 belt between them at the equator. The great red spot is fairly 

 distinct in outline, though quite pale — a feeble red. The great 

 bay in the south equatorial belt north of the red spot is still per- 

 sistent and well marked." Prof. Barnard has observed a 

 number of small black and white spots in Jupiter's northern 

 hemisphere. Two of these objects, a black and a white spot, 

 can easily be seen opposite the great red spot on the planet's 

 disc. Prof. Barnard's measures indicate that the white spot 

 will be in conjunction with the dark one about the middle of 

 January next year, but as the two objects are not exactly on the 

 same parallel, they will only graze in passing one another. The 

 black spot appears to have about the same rotation period of the 

 great red spot. Numerous white spots have been observed in 

 Jupiter's southern hemisphere. .\ few dusky markings have 

 also been seen on the great white equatorial belt. 



THE NEW CYPRESS OF NYASALAND. 

 TN the most easterly corner of the British Protectorate ofNyasa- 

 land, immediately south of Lake Shirwa (between 35' and 

 36" E. lal, and a little north of 16° S. lat.), lies the large isolated 

 mountain-mass of Milanji. From the plains which surround it 

 the land rises gradually to a height of about 3000 feet, and 

 for^js the lower spurs of the mountain. Above these outlic 

 the mount.iin is carried up another 3000 feet in abrupt elevatior* / 

 only broken in places where the larger streams flow down. ""'^ 



