422 



NA TURE 



[March 3, 1892 



nesium are capable of formation, one of which is unstable, and, 

 as shown by Messrs. Jones and Taylor, is decomposed by water 

 with evolution of a mixture of hydrogen and boron hydride, | 

 while the other is permanent both in the presence of water and 

 acids. It is this stable boride, which M. Moissan has obtained 

 in good crystals, which is so difficult to remove from the sub- 

 stance which has hitherto been considered as amorphous boron, 

 and its formation should be avoided as much as possible. When 

 magnesium and boric anhydride in the proportions above indi- 

 cated — convenient quantities being 70 grams of the former and j 

 210 grams of the latter— are heated to redness in a closed j 

 crucible, a somewhat violent reaction occurs, the crucible be- | 

 coming vividly incandescent. Upon cooling, a reddish-brown 

 mass is found, which is readily detached from the crucible, and 

 is impregnated throughout with crystals of magnesium borate. 

 The interior portion is then powdered, and successively treated j 

 with water and hydrochloric acid, alcoholic potash, hydrofluoric \ 

 acid, and lastly with distilled water. This product, even after 

 such exhaustive treatment, upon drying in vacuo, is found to con- 

 tain only 95 per cent, of boron. In order to remove the 5 per 

 cent, of the stable boride, the product is again heated to redness 

 in the midst of a large excess of boric anhydride, and the extrac- 

 tion and washing repeated as before. The percentage of boron 

 is by this means raised to 98"3 per cent., the remaining impurity ! 

 being a mere trace of the boride and i -3 per cent, of nitride of 

 boron. These remaining impurities have finally been eliminated | 

 by employing a crucible rendered impenetrable to the furnace I 

 gases, the nitrogen of which rapidly causes the formation of \ 

 nitride, by means of a mixture of titanic acid and charcoal. In 

 addition to the laborious method above indicated, by which 

 tolerably large quantities of pure boron may be obtained, M. 

 Moissan further shows that it may be prepared in smaller ^ 

 quantities by the reduction of boric anhydride by magnesium in 

 a stream of hydrogen, when, after extraction, a pure product 

 necessarily free from nitride is obtained. And lastly, M. Mois- 

 san describes an electrolytical method of preparing it. Fused 

 boric acid is rendered a good conductor of electricity by the 

 addition of 20 per cent, of its weight of borax. Upon passing 

 through the fused mixture a current of 35 amperes, a little 

 sodium is liberated at the negative pole, and combines with the 

 platinum electrode to form an alloy, while amorphous boron and I 

 oxygen are liberated at the positive pole. The greater portion j 

 of the boron, owing to the high temperature of the reaction, | 

 recombines with the oxygen with most brilliant incandescence, [ 

 but a portion escapes combination, and may be isolated in the j 

 pure state as a chestnut-coloured powder. I 



The additions to the Zoological Society's Gardens during the 

 past week include a Green Monkey {Cercopithecus callitrichus $, ) 

 from West Africa, presented by Mr. George W. Bowles ; a 

 Toque Monkey {Macactis pileatiis) from Ceylon, presented by 

 Mr. Arthur Wallis ; a Bauer's Parrakeet {Platycercus zonarius) 

 from South Australia, presented by Mr. Edward F. Baiilou ; 

 two Alpine Accentors {Accentor collaris), European, presented 

 by Lord Lilford, F. Z. S. ; four Coqui Francolins {Francolinus 

 coqui 2 (J 2 9 ) from South Africa, presented by the Hon. F. 

 Erskine ; a Green Toad {Bufo vi7-idis), six Painted Frogs 

 {Discoglossus pictus), European, three Moorish Toads [Bufo 

 matiritanica) from Tunis, purchased. 



OUR ASTRONOMICAL COLUMN. 

 The Warner Observatory. — "The Warner Observatory 

 is distinctively a private institution built for the purposes of 

 original discovery rather than the ordinary routine work of most 

 other Observatories." This sentence begins a recently-published 

 history and work of the Warner Observatory, Rochester, N.Y., 

 from 1883 to 1886. Under such favourable condilions as these. 



NO. II 66, VOL. 45] 



it is not wonderful that a considerable amount of work should 

 be done. Mr. Lewis Swift is the Director of the Observatory, 

 and, upon assuming command, he selected the discovery of new 

 nebulae as his principal field of labour. The first unrecorded 

 nebula was found on July 9, 1883. Since then more than 400 

 others have been detected ; and their positions and descriptions 

 have been published from time to time in four catalogues. The 

 observations are now brought together, and will therefore be 

 more useful than heretofore. In the volume containing them 

 are printed the Warner prize essays. One of these, by Prof. 

 Lewis Boss, treats of "Comets: their Composition, Purpose, 

 and Effect upon the Earth " ; and there are several others on the 

 coloured skies seen about the time of the Krakatab eruption. 

 Mr. Henry Maine endeavours to show that a physical connection 

 existed between these red sunsets and solar activity. The Rev. 

 S. E. Bishop, of Honolulu, also describes the brilliant glows in 

 question ; ascribing them to the introduction of finely divided 

 matter into the higher regions of the atmosphere. 



Measurementof Solar Prominences. — In Comptesrendus, 

 tome cxiii. p. 353 (1891), M. Fizeau pointed out that the 

 velocities attained by solar prominences were comparable with 

 the earth's orbital velocity, and remarked that, on account of 

 this circumstance, prominences must suff"er a displacement from 

 their true position. If this were so, and the argument appeared 

 to be sound, then the apparent heights reached would have to be 

 increased or diminished according to the velocity with which the 

 prominences were projected. Mr. Henry Crow has pointed out 

 an apparent error in this reasoning {Astronomy and Astro- 

 Physics, January, p. 90). He says : — " The author here neglects 

 the fact that, at any given instant, each point of the solar disk 

 and of the prominence, whether in motion or at rest, is sending 

 to the observer rays, all of which are affected by the same 

 correction for aberration. I say the ' same ' correction, since 

 the change in celestial longitude or latitude from one part of 

 the sun's surface to another would affect the aberration quite 

 inappreciably. If there be relative motion among the parts of 

 the. prominence, then, since at any instant aberration aff'ects all 

 these parts to the same extent, the prominence will be projected 

 upon the slit of the spectroscope in its true proportions." So the 

 study of the solar surface is apparently not to be complicated by 

 the introduction of a new correction. In this connection it may 

 be remarked that, in a letter dated February 12, Prof. Hale 

 writes: "You may be interested to know that I have just 

 succeeded in photographing all the prominences around the sun 

 with a .single exposure." 



THE A USTRALASIAN ASSOCIA TIONFOR THE 

 ADVANCEMENT OF SCIENCE. 



nrUE Australasian Association for the Advancement of Science 

 ■^ held its fourth annual meeting at Hobart, Tasmania, from 

 January 7 to 14 inclusive. The meeting was in every way 

 successful, and the proceedings afTord ample and most satisfactory 

 evidence that much excellent work is being done among our 

 Australa'iian kinsfolk in every branch of science. The President 

 was His Excellency Sir Robert Hamilton, Governor of Tas- 

 mania. The people of Hobart accorded to the members of the 

 Association a most hearty welcome, and did everything in their 

 power to make the occasion a pleasant and memorable one. 

 Visitors from a distance had the advantage of being able to 

 travel both by sea and land at greatly reduced fares, and 

 everything of scientific interest in Tasmania was clearly explained 

 for them in a capital hand-book issued from the Government 

 Printing Office. Mr. Robert Giffen attended the meeting, and 

 was cordially received. He delivered a lecture to the members 

 of the Association on "The Rise and Growth of the British 

 Empire." 



Great credit is due to the Hobart Mercury and other local 

 papers for the enterprise they displayed in reporting the pro- 

 ceedings. 



At the meeting of the general Council on January 7, 

 the chair was taken by Baron von Mueller, past President, as 

 Sir James Hector, the retiring President, was prevented by ill 

 health fiom being present. It was formally decided that the 

 fifth annual meeting ot the Association .should be held at 

 Adelaide, and practically decided that the sixth should be held 

 at Brisbane. Prof. Tate will be President of the Adelaide 

 meeting. 



