May 12, 1887] 



NATURE 



43 



l>erature it is transparent in very thin layers, but is almost opaque 

 in layers 2 mm. thick. In order to determine its boiling-point, 

 the tube containing it was introduced into a vessel containing 

 liquid ethylene cooled to about - 140°. The ozone still retained 

 the liquid form, and only began to vaporize when the tempera- 

 ture of the ethylene had risen to near its boiling-point. The 

 temperature of the ethylene was determined by means of a 

 carbon bisulphide thermometer, which at the moment of incipient 

 ebullition of the ozone indicated a temperature of - 109°, this 

 corresponding to - 106° of the hydrogen thermometer. The 

 boiling-point of pure ozone is therefore approximately - 106°. 

 Experiments with liquid ozone require great caution on account 

 of the readiness with which explosions occur. If, for instance, 

 liquid ozone comes into contact with ethylene gas, an extremely 

 violent explosion occurs in spite of the low temperature. It is 

 therefore necessary to exclude the inflammable gas from contact 

 with the ozone, and then explosion need not be feared. 



Not less interesting than syntheses of vegetable or animal 

 principles are the attempts which are made from time to time to 

 build up minerals of the same crystalline form and chemical 

 composition as those occurring upon the surface of our planet. 

 One of the most widely distributed minerals — the historic mag- 

 netite — found so universally throughout the whole of the more 

 basic rocks, and the square or triangular sections of which are 

 familiar to every micro-petrologist, has long been a favourite 

 subject for attempts, partially succe-.sful, at artificial reproduc- 

 tion. But probably the best method of effecting this has of late 

 been devised by M. Alex. Gorgeu {Comptes rendus, No. 17, 

 1887), who has obtained fine crystals, sufficiently large to enable 

 him to prove their complete identity with those of native mag- 

 netite. His method was to drop iron wire or filings into a bath 

 of fused sulphite and sulphide of sodium, when a double sulphide 

 of iron and sodium was formed, together with an oxide of iron 

 richer in protoxide than magnetite ; in a short time this oxidized 

 to magnetite, and the sulphide and sulphite were converted to 

 sulphate of sodium. The crystals of magnetite obtained, when 

 washed free from the sodium sulphate, were a millimetre in 

 section, of octahedral form modified by faces of the rhombic 

 dodecahedron, and attracted by the magnet ; they possessed the 

 metallic lustre and the same specific gravity and hardness as 

 crystals of naturally occurring magnetite. 



We have received the second edition of Miss Gierke's 

 "Popular History of Astronomy during the Nineteenth 

 Century," published by Messrs A. and C. Black. We regard it 

 as a most encouraging sign of the times that in a period of not 

 over eighteen months, the first edition of such a book as 

 this should have been exhausted. It shows that the number of 

 persons interested in astronomical science who care to read 

 sound treatises requiring a considerable amount of attention is 

 on the increase, and we know no book which is likely to foster 

 the love of the subject amo:ig such paople better than Miss 

 Gierke's. The mere process of bringing up to date has involved the 

 insertion of a considerable amount of new matter. Celestial 

 j)hotography naturally comes in for an added share of attention, 

 directed chiefly to the discoveries of nebulae in the Pleiades by 

 the MM. Henry and Mr. Roberts ;to the work in stellar spectral 

 photography in progress at Harvard College ; and to the pre- 

 liminary essays in photographic charting made at Paris, Liver- 

 jiool, and the Gape of Good Hope. Other new or extended 

 iiassages relate to the bright-line spectra of -> Cassiopeiae and /3 

 I .yrse, stellar photometry, the effects of tidal friction on the satel- 

 lite system of Mars, and the daylight photography of the sun's 

 corona. The theory of sunspots unfolded by Mr. Lockyer 

 in his " Chemistry of the Sun " finds a place in the chapter on 

 " Solar Observations and Theories," and that on " Solar 

 Spectroscopy " includes an account of the observations of the 



spectra of sunspots at South Kensington, 1879-85, with their 

 results for solar chemistry. We notice some modification in the 

 author's views regarding the dissociation of terrestrial elements 

 in the sun, the presence of the bright-line spectrum of oxygen 

 in the solar spectrum, and Young's "reversing layer." She 

 moreover (apparently on good grounds) withdraws the statement 

 that comets, moving sensibly in the same track in the parts of 

 their orbits near the sun, must have nearly identical periodic 

 times. Paragraphs in the new edition are assigned respectively 

 to the last comer (Comet 1887 I.) of the remarkable group con- 

 nected with the comet of 1843, and to the singularities of Comet 

 Pons-Brooks ; while the observations on the meteors of 

 November 27, 1885, on the new star in Andromeda, and at 

 Grenada during the total eclipse of August 29, 1886, are fully 

 particularized. We are glad to perceive that Miss Gierke has 

 taken advantage of many of the hints of her critics, supplying, 

 for instance, the few omissions in her work pointed out by Sir 

 Robert Ball in Nature (vol. xxxiii. p. 314). A completely new 

 feature is a chronological table of the principal astronomical 

 events between the years 1774 and 1887 ; and a frontispiece and 

 vignette, reproducing Mr. Common's and the MM. Henry's 

 photographs of the Orion Nebula, Jupiter, and Saturn, add to 

 the attractions of the second edition. 



The additions to the Zoological Society's Gardens during the 

 past week include a Bonnet Monkey {Macacus sinicus) from 

 India, presented by Mr. G. Lester ; a Brazilian Tree-Porcupine 

 {Sphinghurus prehenstlis) from Brazil, presented by Dr. William 

 Studart ; a Vervet Monkey {Cercopithecus lalandii) from South 

 Africa, presented ; a Domestic Sheep {Ovis aries, four-horned 

 var.) from Arabia, presented by Mr. C. E. Kane ; a Tooth- 

 billed Pigeon {Dldimculus strigirostris) from the Samoan 

 Islands, presented by Mr. Wilfred Powell ; a Great-crested 

 Grebe (Podiceps cristatus) from Norfolk, presented by Mr. T. E. 

 Gunn ; a Goldfinch {Carduelis elegans), a Greenfinch (Ligurinut 

 chloris), a Red Bunting {Emberiza schcenichus), British, pre- 

 sented by Master H. J. Walton ; an Eyed Lizard {Lacerla ocel- 

 lata) from Cannes, presented by Mr. J. E. Warburg ; a Smooth 

 Snake {Coronella IcBvis) from Hampshire, presented by Mr. 

 H. B. Pain; a Green Turtle (Chelone viridis) from Ascension, 

 presented by Dr. Keenan ; a Squirrel Monkey ( Chrysolhrix 

 sciurea) from Guiana, a Servaline Cat {Felis servalina) from 

 West Africa, a Black-necked Swan {Cygnus nigricollis) from 

 Antarctic America, two Natterer's Snakes {Thamnodynastes 

 natlereri) from Brazil, purchased ; four Prairie Marmots 

 {Cynomys ludovicianus), born in the Gardens. 



OUR ASTRONOMICAL COLUMN. 



The Melbourne Observatory. — Mr. EUery has recently 

 issued his Annual Report referring to the year ending June 30, 

 1886. From it we learn that the new transit-circle has been in 

 constant use during the year, and is in excellent order. There 

 appears, however, to be a very gradual lowering of the west 

 pier of the instrument since its erection in August 1884. There 

 also appears a decided diurnal change in the level, the east pivot 

 being higher in the morning and lower in the evening — probably 

 due to the heating effects of the sun on the earth's crust, or on 

 the building. The objects observed with the transit-circle 

 during the year comprised fundamental clock stars, standard 

 circumpolar stars, faint stars selected from the Melbourne zones, 

 comet stars, refraction stars, and a list of stars proposed for 

 insertion in the Connaissance des Temps. The great telescope 

 was almost exclusively devoted to the revision of the southern 

 nebulae. During the year 214 of Sir J. Herschel's nebulae were 

 finally revised, 7 were searched for but not found, whilst 30 

 new nebulae were discovered. There now remain only 95 

 I nebulae, which were observed by former observers, requiring 

 \ final revision before publication. The photoheliograph was not 

 in working order for several months during the year, owing to 

 difficulties arising from the change in the size of the sun pictures 



