Nov. 19, 1885] NATURE 



Moon (at Full) rises, l6h. 43m. ; souths, oh. 25m. 

 Sh. 14m.*; decl. on meridian, 17° i' N. 



: visible at Greenwich. 

 Nov. h. 



24 ... 23 ... Saturn in conjunction with and 3° 59' north 



of the Moon. 

 A special watch should be kept on November 27 and the days 

 immediately preceding and following, in order to note whether 

 there is any recurrence of the meteoric shower observed on 

 November 27, 1872, and believed to be connected with Biela's 

 comet. The radiant point is near 7 Andromedee. 



CHEMICAL NOTES 

 In order to obtain constant temperatures easily maintained 

 and completely under control, Messrs. I-iamsay and 'i'oung 

 (C. S. Journal, Trans., 18S5, 640) einploy vapours of the 

 following compounds, and alter the pressure to which each 

 vapour is subjected : carbon disulphide, ethyl alcohol, chloro- 

 benzene, bromobenzene, aniline, methyl salicylate, bromo- 

 naphthalene, and mercury. By the use of the vapours of these 

 bodies at various pressures, any desired temperature between 

 that of the atmosphere and 360° can be easily obtained. The 

 authors have very carefully determined the vapour-pressures of 

 these compounds for a large range of temperature. The 

 methods of experiment are fully described, and the results are 

 presented in the form of tables, whicli must prove of much 

 service to those chemists and physicists who have occasion to 

 raise pieces of apparatus to a Icnown temperature, to vary that 

 temperature if required, or to l<eep it perfectly constant for an 

 indefinite period. 



As was noticed in these columns some time ago, Dixon has 

 recently proved that a mixture of perfectly dry carbon monoxide 

 and oxygen is not exploded by the passage of electric sparks ; 

 but that ihe presence of a minute quantity of water suffices to 

 determine the combination of the gases. Dixon supposed that 

 the action of the water was as represented in the following two 

 equations : — 



(i) CO + H.O = CO., + H., 



(2) 2H2 -I- Oj = 2H2O". 



NowTratibe [Ber. 18, 1S90) has shown that carbon monoxide 

 does not decompose water in complete absence of air or oxygen, 

 even at very high temperatures ; he has also shown that when 

 moist carbon monoxide and oxygen are exjiloded together, 

 hydrogen peroxide is an invariable product. Traube suggests 



that the following three changes probably occur during the 

 explosion in question : — 



(1) CO-f2H..O-t-Oa = CO(0H)., + H„O.,. 



(2) CO-f H„0., = CO(OH).,. 



(3) 2CO(OH).>2CO.,-f-2H.jO. 



When liydrogen is burnt in moist oxygen, hydrogen peroxide is 

 always produced, according to Traube. Whether a perfectly 

 dry mixture of hydrogen and oxygen could or could not be ex- 

 ploded by electric sparks cannot be regarded as settled ; Traube 

 thinks tliat such a mixture would prove to be non-explosible. 

 He regards the mutual action of hydrogen, oxygen and water as 

 in all respects comparable with that of carbon monoxide, oxyijen, 

 and water, or with that of zinc, lead, and some other metals, 

 oxygen, and water. The changes which occur in the explosion 

 of moist hydrogen and oxygen are formulated by Traube thus : — 

 (i) H.,-i-2H.,0-t-0., = 2H20 4-H20.,. 



(2) H20.j-f H2 = 2H20. 



The occurrence of the second part of this reaction has been 

 experimentally demonstrated by Traube. 



In continuing his experiments on nitrification, Warington 

 {C.S. Journal, Trans. 18S5, 75S) has shown that the limit of 

 concentration (about 12 per cent.) beyond which urine ceases to 

 be nilrifiable under ordinary conditions may be largely extended 

 by adding gypsum to the liquid. A solution containing 50 per 

 cent, of urine, and 22 milligrams of gypsum for every c.c. of 

 urine, began to nitrify after about five months ; solutions con- 

 taining 15, 20, and 30 per cent, of urine began to nitrify after 

 the lapse of 53, 68, and 78 days respectively. The gypsum 

 prevents the accumulation of ammonium carbonate in the liquid. 



J. H. v.^n't Hoff describes [BerUhte, xviii. 20S8) experi- 

 ments on phenomena, analogous to those exhibited by gases at 

 their "critical points," occurring during chemical decomposi- 

 tion. I'hosphonium chloride, PH4CI, which mells at 25°, was 

 heated to 50°-5l° at a pressure of 80-90 atmospheres in a 

 Cailletet's apparatus ; under these conditions the line of separa- 

 tion between liquid and vapour disappeared, and, on cooling, 

 the formation of nebulous streaks became plainly visible. It is 

 well known that the vapour obtained by heating PH.jCl under 

 ordinary conditions consists of PHg -f HCl ; it is not possible 

 to say to what extent the melted substance in van't Hoff's 

 experiment consisted of a compound of PH3 and HCl, and the 

 gaseous part consisted of a mixture of these constituents, yet it 

 seems certain that, when PH.,C1, a compound which is chemi- 

 cally decomposed when vaporised, is heated to 50° under a 

 pressure of 80-90 atmospheres, there exists identity between the 

 vapour and the condensed portion of the body. 



La Coste describes (Berichte, xviii. 2122) a modification of 

 V. Meyer's apparatus whereby the densities of easily decomposed 

 compounds may be determined at low temperatures under small 

 pressure.'^. 



GEOGRAPHICAL NOTES 

 A CATALOGUE of the printed maps, plans, and charts in the 

 British Museum has been prepared by Prof. Douglas, and will 

 be issued in two large volumes. It represents the contents of 

 the manuscript catalogue in 323 volumes, the catalogue of the 

 maps and plans in the Royal Library in two printed volumes, 

 and the manuscript catalogue of charts in the same lilirary. The 

 original manuscript catalogue was made under the superintend- 

 ence of Mr. Major, late Keeper of the Department of Maps. 

 The orlhograpliy adopted in the present catalogue is that used 

 in Keith Johnston's "General Dictionary of Geography," 

 with the exception of India, for which Hunter's "Gazetteer" 

 has been taken as a guide. The utility of this catalogue to the 

 geographical student will be found in tiie comparatively simple 

 alphabetical arrangements for the heading.; of countries and 

 places, combined with the names of geographical writers, which 

 last often serve a^ short cuts to any particular atlas or map. 

 Thus, under the head of " Ptolemy," the pillar and foundation 

 of ancient geography, there are seventy-four entries referring to 

 the various editions and copies of his " Geographica." Turning 

 to the names of the fathers of modern geography, Ortelius and 

 Mercator, we find under tlie former twenty-nine entries describ- 

 ing the various copies and editions of his " Theatrum orbis 

 Terrarum." The geographical labours of his contemporary and 

 friend, Mercator, will be best realised by a reference to the 



