422 Scientific Intelligence. 



These two gases do not react upon each other even when a mix- 

 ture of them is passed over heated soda-lime. But in presence of 

 sodium, action readily takes place, owing to the production first 

 of sodium amide, which then reacts with the monoxide to yield 

 the sodium salt of azoimide, thus: NaNH 2 + N 2 = NaN 3 + H a O. 

 The sodium salt being less explosive than most of the other salts 

 of azoimide, the experiment may be safely performed if proper 

 care is exercised. The sodium in small pieces is placed in several 

 porcelain boats in a combustion tube and the air is displaced 

 by a current of ammonia gas. On heating the tube the sodium 

 fuses and is converted into sodamide. Then the current of am- 

 monia is replaced by one of nitrogen monoxide, and the tempera- 

 ture is reduced to between 150° and 250°, by surrounding the 

 tube by an air bath. The sodamide increases in bulk and be- 

 comes sodium azoimide, the reaction being completed when am- 

 monia no longer escapes. This salt may also be obtained by 

 passing a mixture of nitrogen monoxide and ammonia over 

 metallic sodium ; but the yield is smaller and the sodium some- 

 times inflames in the monoxide. On throwing the product into 

 water, and distilling the filtered solution with dilute sulphuric 

 acid, the distillate possesses the intolerable odor of azoimide and 

 gives precipitates with silver, lead, and mercurous nitrates, which 

 correspond in properties with these salts of azoimide. The 

 silver salt gave 7l"7 per cent of silver, AgN" 3 requiring 71*8 per 

 cent. Potassium and zinc may also be used in place of sodium. — 

 Ber. Berl. Chem. Ges., xxv, 2084, July, 1892; Nature, xlvi, 286, 

 July, 1892. G. F. b. . 



6. On Metallic Carbonyls. — On the 3d of June, a Friday 

 evening discourse on metallic carbonyls was given at the Royal 

 Institution by Ltjdwig- Mond. After referring to the potassium- 

 carbonyl of Liebig as the first metallic carbonyl, he entered upon 

 a consideration of the nickel-carbonyl, discovered three years ago 

 by himself, in connection with Langer and Quincke. The nickel, 

 prepared in a fine state of division by heating the oxalate in a 

 current of hydrogen, is treated with carbon monoxide at a low 

 temperature. The escaping nickel-carbonyl, cooled in a freezing 

 mixture, is condensed to a colorless liquid, which freezes at — 25° 

 in needle-shaped crystals. The vapor has a characteristic odor 

 and is poisonous. It decomposes at about 200° depositing a mir- 

 ror oi metallic nickel. Its magnetic properties, according to 

 Quincke, are remarkable since it is diamagnetic to a high degree, 

 all other nickel compounds being paramagnetic. It is also an 

 excellent insulator. Its spectrum, observed by Liveing and 

 Dewar, shows that it is opaque for all rays beyond wave-length 

 3820. On diluting its vapor with hydrogen, the flame on burn- 

 ing is bright yellowish green and gives a spectrum having a bright 

 background on which are superposed a number of bands. In the 

 ultra-violet fifty well-defined lines are observed corresponding 

 exactly to lines in the spark spectrum of nickel. The magnetic 

 rotation of nickel carbonyl, as observed by Dr. Perkin, is found to 



