August 14, 1890] 



NATURE 



n^ 



The final arrangement adopted for the preparation of 

 the liquid is as follows. A quantity of nickel oxide is 

 placed in a combustion tube, and reduced at about 400' 

 by the passage of a current of hydrogen gas. The tube 

 and contents are then cooled down to about 30°, and pure 

 dry carbon monoxide instead of hydrogen passed through 

 the tube without further heating it. The issuing gas is 

 caused to pass through a Y tube surrounded by ice and 

 salt. The lower end of the Y tube projects through the 

 vessel containing the freezing mixture into a small flask 

 in which the liquid collects. The gas leaving the Y tube 

 still retains about 5 per cent, of the new body, and is 

 therefore collected, dried, and again passed over the 

 nickel until no more liquid condenses. The tube con- 

 taining the nickel is then re-heated to 400° in a slow 

 current of hydrogen, again cooled, and the operation re- 

 commenced. In this manner it is easy to obtain ten to 

 fifteen grams of the liquid in each operation. 



The liquid boils at 43° under a pressure of 751 mm. 

 Its specific gravity is 1-3185 at 17°, At-25° it solidifies to 

 a mass of needle-shaped crystals. The liquid is soluble 

 in alcohol, and even more readily in benzene and chloro- 

 form. It is perfectly indifferent to dilute acids and 

 alkalies, and is not attacked by concentrated hydrochloric 

 acid. Strong nitric acid oxidizes it readily. As regards 

 its composition, the nickel was estimated by weighing the 

 nickel deposited on passing repeatedly through a heated 

 tube, and the carbon by passing the vapour rnixed with 

 air over copper oxide, and absorbing and weighing the 

 carbon dioxide produced. The following numbers were 

 obtained : — 



Calculated isc 

 I. II. Ni(C0)4. 



Nickel ... 33-35 ... 33"37 ••• 3434 

 CO ... 6660 ... 65-99 ... 65-66 



Its composition, therefore, appears to be represented by 

 the formula Ni(C0)4. Its vapour density, the first density 

 determination of a nickel compound, was determined by 

 Victor Meyer's method at 50^. The value obtained was 

 6-OI. Ni(CO)4 corresponds to the density 5-9. At 60° the 

 vapour was found to explode with considerable violence. 



Vapour of nickel-carbon oxide, as its discoverers term 

 it, reduces an ammoniacal solution of cuprous chloride, 

 first decolorizing it and subsequently precipitating from 

 it metallic copper. It also precipitates metallic silver 

 from ammoniacal solutions of silver chloride. Chlorine 

 decomposes it with production of nickelous chloride, 

 NiCIo, and carbon oxychloride, COCU. Bromine reacts in 

 a precisely similar manner. The electric spark decom- 

 poses it slowly into nickel and carbon monoxide. 



Experiments have also been made to ascertain the 

 possibility or otherwise of preparing a similar compound 

 of cobalt and carbon monoxide. It was found, however, 

 that cobalt does not form such a compound ; indeed, it 

 is quite possible to separate nickel from cobalt by re- 

 acting with carbon monoxide in the above manner, the 

 nickel only being removed. The metallic mirrors ob- 

 tained by the decomposition of nickel-carbon oxide by 

 heat were found to consist of unusually pure nickel, con- 

 taining no traces of cobalt. They consisted of a grey 

 metallic powder of specific gravity 8-2834 at I5°'4. 



It became interesting, therefore, to ascertain the atomic 

 weight of this pure nickel, especially in view of the recent 

 work of Drs. Kriiss and Schmidt. Accordingly, a series 

 of three determinations were made, with the following 

 results :— If O = 16, Ni = 58-58, 58-64, and 58-52. These 

 numbers are sufficiently close to the value 5874, long ago 

 obtained by Dr. Russell, to justify the conclusion that 

 nickel, as we have known it, is indeed a simple sub- 

 stance, whose atomic weight lies very near to the figure 

 hitherto accepted — a conclusion which is further sup- 

 ported by the determination of the vapour density of this 

 remarkable new compound, nickel-carbon oxide. 



A. E. TUTTON 



NO. 1085, VOL. 42] 



BRITISH MUSEUM NATURAL HISTORY 

 PUBLICATIONS} 



THE present Part (IV.) concludes Mr. Lydekker's 

 "Catalogue of the Fossil Reptilia and Amphibia 

 in the British Museum (Natural History)," the four 

 volumes making together a work of 1247 pages. In 

 Part I. the author records <he Ornithosauria, the Croco- 

 dilia, the Dinosauria, the Squamata, the Rhyncho- 

 cephalia, and the Proterosauria ; Part II. contains the 

 Ichthyopterygia and Sauropterygia ; Part III. embraces 

 the Chelonia; and Part IV. the anomalous group of the 

 Placodontia, the Anomodontia, and the class, Amphibia, 



/ 



Fig. I. — Cyavwdus (J'lacodus) laticeps, Owen, a, palatal aspect ; b, frontal 

 aspect of cranium ; from the Muschelkalk of Baireuth, Germany. 



including the Ecaudata, the Caudata, and the Laby- 

 rinthodontia, with supplementary notes and additions to 

 the preceding orders. The earlier parts having been 

 already noticed in Nature, we shall confine our 

 attention to Part IV. 



Amongst the rare remains of Reptilia met with in the 

 Muschelkalk of Baireuth, Bavaria, none are of more 

 interest than those belonging to the anomalous group of 

 the Placodontia, the ordinal position of which is still 

 uncertain. The skull and teeth of one of these reptiles 



* " Catalogue of the Fossil Reptilia and Amphibia in the British Museum 

 (Natural History), Cromwell Road, S.W." Part IV., containing the Orders 

 Anomodontia, Ecaudata, Caudata. and Labyrinthodontia ; and Supplement. 

 By Richard Lydekker, B.A,, F.G.S., &c. Pp. 29s and xxiv. With Index to 

 the entire Work. Illustrated by 66 Woodcuts. (London : Printed by Order 

 of the Trustees : and sold by Longmans and Co. ; B. Quaritch ; Asher 

 and Co. ; Kegan Paul, Trench, Triibner, and Co., &c., 1890), 



