328 



NA TURE 



[August I, 1889 



illustrate the geographical distribution of butterflies, and three 

 portraits of early naturalists of America; in all about 2000 

 figures on ninety-six plates, of which forty-one are coloured. 

 The text contains 2000 pages, including an introduction of 104 

 pages, and an appendix, of 150 pages, which contains descrip- 

 tions of such species concerned as have not been found within 

 the limits of New England, and also descriptions of all known 

 parasites of North American butterflies, by Messrs. Howard and 

 Williston. 



The City of London College Science Society has issued its 

 Report for 1888-89. We are glad to see that the session was 

 one of increased activity, and, as the Committee are able to add, of 

 continued success. Papers on subjects of great scientific interest 

 were read, and there were many excursions to places suitable for 

 geological study and for the collection of botanical and zoological 

 specimens. The Society now publishes a monthly journal. 



Mr. Percy Lindley is editing a series of " Holiday Hand- 

 books." One of those sent to us deals with the Hartz Mountains, 

 another with the Ardennes. They cost only a penny each, and 

 are well done. For the same price one may now get a very 

 good little illustrated Guide to London. It is published by Mr. 

 J. P. Murray. 



The tenth part of Cassell's "New Popular Educator" has 

 been issued. It is well illustrated, and has a good map of 

 British North America. 



A remarkable series of experiments illustrating an extreme 

 case of " mass" or "catalytic" action are described by Messrs. 

 Morseand White of the University of Pennsylvania, Philadelphia, 

 in the current number of the American Chemical Journal (p. 

 348). The sulphides and oxides of zinc and cadmium, which are 

 so difficultly volatiiizable when heated alone, are found to be 

 readily volatiiizable in presence of their respective metals, zinc 

 or cadmium, owing to alternate dissociation and recombination. 

 The. pure sulphides were first prepared by dissolving redistilled 

 zinc or cadmium in hydrochloric acid and precipitating with 

 sulphuretted hydrogen. The washed pr cipitates were next dried 

 in the ordinary way, and then heated to 300° C. in a current of 

 pure dry sulphuretted hydrogen. They were finally repeatedly 

 treated with carbon bisulphide to remove any traces of free 

 sulphur. The sulphides as thus prepared were found to be per- 

 fectly stable in a vacuum, the exhausted tubes containing them 

 being heated until the glass softened and collapsed without any 

 signs of volatility of the sulphides being apparent. About 15 

 grams of either of the sulphides wei-e then mixed with 40 grams 

 of the corresponding metal and placed at the sealed end of a 

 combustion tube, the other end being connected with a Sprengel 

 pump. The end containing the mixture was placed in a furnace, 

 and after the exhaustion was completed as far as possible, was 

 gradually heated. As the temperature rose the metal began to 

 fuse, and a yellowish white film of sulphur was formed in the 

 cool portion of the tube projecting out of the furnace. The for- 

 mation of this deposit is due to the fact that while the tube is 

 comparatively free from the metallic vapour, the sulphur liberated 

 by the dissociation of the sulphide, having a higher rate of dif- 

 fusion than the vapour of the metal, partly escapes recombination, 

 and is deposited in the free state in the cooler portion of the tube 

 just outside the furnace. As the temperature still rises this de- 

 posit becomes converted into sulphide, and eventually a long 

 line of crystals of the sulphide is formed along the bottom of the 

 projecting part of the tube. Cadmium sulphide w as found to be 

 transported much further along the tube than zinc sulphide, and 

 the crystals could be seen to form and fall in a manner re- 

 sembling a fine rain. Indeed, so ready is the dissociation of 

 cadmium sulphide under the influence of metallic cadmium that 

 by rapidly raising the temperature the experiment becomes 

 dangerous, the dissociation occurring with almost explosive 



violence. On several occasions when the mixture was too tightly 

 packed into the end of the tube, the whole contents were 

 violently blown into the Sprengel pump. It is necessary to leave ■ 

 a very considerable free space along the top of the tube to insure 

 a successful experiment. It was found that the oxides of zinc 

 and cadmium behave similarly to the sulphides, oxide of zinc in 

 this case dissociating most readily. The singular action of these 

 metals in lessening the stability of their respective oxides and 

 sulphides certainly forms one of the most extreme cases of 

 " mass " or " catalytic " action on record ; and that it is not a< 

 mere mechanical carrying action appears abundantly proved by 

 the slight deposit of sulphur which is always noticed in the 

 earlier stage of the experiment, and by the beautiful manner in ■ 

 which the sulphides themselves are afterwards deposited. 



The additions to the Zoological Society's Gardens during the 

 past week include a Macaque Monkey {Macaciis cynoniolgus i ) * 

 from India, presented by Mr. F. Dobbs ; a Common Otter 

 Lntra vulgaris) from North Wales, presented by Mr. Chas. H. 

 Wynn ; two White Storks {Ciconia alba) from North Africa, 

 presented by Mr. Thomas Hay ; three Well-marked Tortoises 

 Honioptis signatus 6 9 9), four Rufescent Snakes {Leptodira - 

 rufescens), a Many-spotted Snake {Psammophylax imiltimacu- 

 latus), a Spotted Slowworm {Acontias meleagris), a Puff- Adder 

 ( Vipei-a arietans) from South Africa, presented by the Rev. G. 

 H. R. Fisk ; a Tesselated Snake ( Tropidonotiis tessellatus) from 

 Italy, presented by Mr. H. D. Brocklehurst ; two Common 

 Toads {Bufo vulgaris), British, presented by Dr. J. J, Pitcairn ; 

 a Common Zebra {Equus zebra ? ) from South Africa, two 

 Black-eared Marmosets [Hapale penicillata) from South-East 

 Brazil, a Tovi Parrakeet {Biotogerys lovi) from Columbia, a Red. 

 and Blue Macaw (Ara macao) from Central America, deposited ; 

 a Peba Armadillo {Tatasua peba), a Pretre's Amazon (C/irj/^c/iV 



pretrii), a Snake {Helicops leopardinus) from Brazil, a 



White-throated Capuchin {Cebus hypoleucus 6) from Central 

 America, a Senegal Touracou {Corythaix persa) from West 

 Africa, six Spotted Tinamous {Nothura maculosa) from Buenos 

 Ayres, a Tesselated Snake {Tropidonotus tessellatus) from Italy, 

 purchased ; two Mule Deer {Cariacus macrotis), two Crested 

 Pigeons {Ocyp/iaps lophotes), bred in the Gardens. 



OUR ASTRONOMICAL COLUMN. 



Discovery of a New Comet, 1889 e. — A telegram from 

 Melbourne to Prof. Krueger announces the discovery of a bright 

 comet by Mr. Davidson, of Queensland, on July 21. The 

 following positions of this comet have been obtained : — 



Place. G.M.T. R.A. N.P.D. 



h. m. s. h. m. s. o / /' 



Melbourne ... July 22 23 3 50 ... 12 46 9-0 ... 122 29 6 



Rome July 27 8 37 4 ... 13 37 29-9 ... no 19 2 



The comet is therefore coming north very rapidly. 



Comet 1889 d (Brooks). — The following elements and 

 ephemeris for this comet are by Dr. H. Oppenheim : — 



T = I? 



August 3*40 G.M.T. 



■K = 339 37 1 



9, = 28 13 > Mean Eq. 1889*0. 

 * = 5 56 j 

 a = o'3627 



The comet probably has a short period. 



Ephemeris for Greenwich Midnight. 

 Decl. 

 3S. 



1889. R.A. 



h. m. 



July 31 ... o 4"2 ... 7 



Aug. 4 ... o 6'i ... 6 48 



8 ... 077 ... 635S. 



The brightness at discovery is taken as unity. 



Bright- 

 ness. 



I '3 

 I "4 



