October 12, 1893] 



NA TURE 



573 



paration is the fourth, in which the compound is formed by 

 direct synthesis by the union of vapour of carbDn with vapour of 

 silicon. For, as has been previously described in these columns, 

 M. Moissan is able to actually distil carbon at the high tem- 

 perature of the arc which he is able to produce in his furnace. 

 The experiment is conducted in a small crucible of pure carbon 

 of elongated form, and enclosing a little block of silicon. The 

 base of the crucible is arranged so as to occupy the position 

 where the highest temperature of the arc is attained, and after 

 the conclusion of the experiment the interior of the crucible is 

 found to be covered with almost colourless prismatic needles of 

 carbon silicide. 



Crystallised carbon silicide is an extremely stable substance 

 which resists the action of the most energetic reagents, even 

 those which are capable of readily attacking its elementary 

 constituents. The pure crystals are colourless and perfectly 

 transparent, and present the appearance of regular hexagons. 

 Their density is 3-12, and they are so hard that the ruby is 

 readily scratched, and may be ground by means of the powdered 

 compound. They are unalterable in air or sulphur vapour at 

 1000°. Chlorine attacks them very slowly at 600°, V)ut more 

 rapidly at 1200". Fused nitre and potassium chlorate are 

 entirely without action upon them, as are likewise boiling sul- 

 phuric, hydrochloric, and nitric acids, and even aqua regia and 

 the silicon-dissolving mixture of nitric and hydrofluoric acids 

 are incapable of attacking them. Fused caustic potash, how- 

 ever, after heating to redness for an hour in contact with them, 

 reacts with formation of carbonate and silicate of potassium, and 

 thus affords a means of estimating the content of silicon. The 

 carbon may also be estimated by repeated combustion with 

 chromate of lead, which gradually effects oxidation of the 

 carbon. The analyses thus carried out agree in all cases with 

 the simple formula CSi. 



Notes from theMirine Biological Station, Plymouth. — Last 

 week's captures include various types oi Foraminifera, colonies 

 of the Hydroid Coryne pusilla (without gonophores), a colony 

 of the Scyphistoma stage of Aurdia, and the Nudibranchs 

 Plalydoris filanala, Caniiiella pleieia ajiA Polycera quadrilineala. 

 In the floating fauna the Hydroid medusa; Cytieandra areolata 

 and Bulima insignis have been observed in addition to the 

 forms mentioned last week. 



The additions to the Zoological Society's Gardens during 

 the past week include a Sooty Mangabey (Cercocebus fuli- 

 ginosus) from West Africa, presented by Mr. Swaniston Cyril 

 Hopkins ; a Serv.il [Felts serval), a Nilotic Crocodile {Croco- 

 dilus vulgaris) from Africa, presented by Mr. T. E. C. Rem- 

 ington ; a Lesser White-nosed Monkey {Cercopithecus petau- 

 risla) from West Africa, presented by Mrs. Noakes ; a Yellow- 

 collared Parrakeet (/'/a/y«'-«<J j^»i!V(;>Yaa/«j) from Australia, 

 presented by Miss A. Fenwick ; a Common Sheldrake ( Tadorna 

 viilpanser) European, presented by the Rev. H. G. Morse ; an 

 Oyster-catcher (Hicmatopus oslralegm) European, presented by 

 Mr. Edmund Elliot ; a Goliath Beetle, from West Africa, 

 presented by Mr. F. W. Marshall ; two Great Eagle Owls 

 (Bubo maximus) European, deposited ; a Flocky Lemur 

 {Avahi: laniger) from Madagascar, a Raccoon-like Dog (Cants 

 procynides) from North-east Asia, a Sanderling (Calidris 

 annaria), a Puffin (Fraiercula arctica) European, purchased. 



OUR ASTRONOMICAL COLUMN. 



Astronomy at the World's Fair. — The astronomical 

 exhibits at Chicago seem to be fairly representative of the 

 state of astronomical science at the present day, but they are 

 too much scattered about in the different buildings for a proper 

 study of them to be made. Among many of the more inter- 

 esting exhibits we may mention the following : Fine collection 



NO. 1250, VOL. 48] 



of astronomical photographs, made by the Harvard College 

 Observatory, which included those of stellar spectra nebulae and 

 clusters, and of a portion of the lunar surface enlarged over one 

 thousand diameters. Dr. Chandler's four inch almacanlar, the 

 collections of Draper and Langley, and the diffraciion gratings 

 and photographs of spectra by Prof. Rowland, the last of which 

 formed the Johns Hopkins University exhibit. Specimens of 

 the famous Jena optical glass, Kirchhofl's original spectroscope. 

 Brill's mathematical models, and the magnetic apparatus of 

 Gauss and Weber form part of the German Educational 

 exhibit. In the English exhibit are found many astronomical 

 photographs by Roberts, Gill, and others ; others from the 

 Royal Observatory, Greenwich, Boeddicker's Milky Way draw- 

 ings, and the fine five-foot glass speculum by Dr. Common. 

 Among some of the exhibits of the American astronomical 

 instrument makers, we are glad to note the mounting of the 

 great forty-inch Yerkes telescope by Warner and Swasey, who 

 exhibit also some minor instruments. J. A. Brashear 

 exhibits the stellar spectroscope for the Yerkes telescope, 

 eighteen-inch and fifteen-inch objectives, gratings, &c. Among 

 G. N. Saegmuller's (of Washington) exhibits is a four-inch 

 steel meridian circle. Two twenty-three-inch discs of the 

 celebrated Jena glass are shown by Schott and Genossen, of 

 Jena, in addition to other specimens of optical glass. In the 

 Cape Colony exhibit Dr. Gills interesting stellar photographs 

 are prominent, while the Lick Observatory display is housed 

 in the educational department of the California State building, 

 and, as Science says, is "strangely enough mixed up with the 

 Kindergarten exhibit there." The U.S. Government building 

 contains interesting apparatus as used in the Coast Survey, 

 while the Naval Observatory shows a small observatory with 

 several instruments. 



The Aurora of July 15, 1893. — The system of observation 

 of the aurora as lately instituted, seems to be already at .work, 

 and the observations of the aurora of July 15, most of which 

 have been made on this system, show that the results are of the 

 highest interest. A brief account of this aurora, by M. A. 

 Veeder, will be found in the Bulletin of the New England 

 Weather Seivice for the month of August (No. 18), from which 

 we gather the following few notes : — With regard to the places 

 of visibility and invisibility, it may be mentioned;that its absence 

 was verified up to midnight in Nova Scotia. In New England 

 it was observed at a tew stations, of short duration, and not at 

 all conspicuous. Towards New York it was a fine display, and 

 lasted all night, and was seen as far south as Washington at this 

 longitude, while it was defined as a fine red aurora at Salt Lake 

 city, and was seen as far south as the Lick Observatory, at both 

 of which places this phenomenon is very rare. A special feature 

 of this aurora was the " formation of a narrow band having an 

 east and west direction, and passing just south of the zenith." 

 This was seen in New England, the neiglibourhood of Lake 

 Ontario, and occasionally in Michigan, Wisconsin, and Iowa. An 

 unusual formation recorded was that of an auroral curtain with a 

 clearly defined lower margin. The twenty-seventh day interval 

 coinciding thus with a synodic revolution of the sun, shows, 

 as M. Veeder says, that whatever it is in the sun that origin- 

 ates an aurora can have this effect only when it has reached 

 a certain position relative to the earth, and, further, that 

 "the effect must proceed from the eastern limb." Ttiat in 

 certain cases of large sunspots auroral effects might proceed 

 from the central meridian of the sun as seen from the earth, 

 M. Veeder freely admits ; but he adds that, until further study 

 has been made, this question cannot as jet be said to be satis- 

 factorily answered. 



New Variable Stars in Cygnus. — A communication to 

 the Astrommischen Nachrichlen, No. 3191, by Herr Fr. 

 Deichmiiller, informs us of two new variable stars in the con- 

 stellation of Cygnus. Their positions are respectively 



h. m. .«. o / 



19 8 27 -f 49 24-2 I g 



20 6 24 -f 47 23 'o \ ■'■' 



The first of these stars has a range of one and a half magnitudes, 

 while the second varies from 7^ to the ninth magnitude. 



AstronomicalWorks (Antiq.). — We have received the 

 catalogue of Herr Oswald Weigel's Antiquarium in Leipsig, 

 which is devoted simply to works on astronomy (astronomical 

 geography and geodecy). Included also is the library of Prof. 

 C. Fearnley, of Christiania; eo that our readers may be sure that 

 there are now some important works for sale. 



