428 Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. On Crystallized Metallic Calcium. — The preparation of 

 practically pure metallic calcium in the crystalline form, has 

 been described by Moissan. For this purpose he has made use 

 of the fact that metallic calcium is soluble in liquid sodium at 

 the temperature of dull redness. On cooling, the calcium crystal- 

 lizes out and on removing the sodium by means of absolute 

 alcohol, white, brilliant hexagonal crystals of pure calcium are 

 obtained. In an iron crucible, holding about a liter, are placed 

 600 grams of crystallized anhydrous calcium iodide and 240 

 grams of sodium ; three times the sodium required by the equa- 

 tion CaI 2 + Na 2 = Ca + (NaI) 2 . The crucible is closed with a 

 screw top and is then placed in a furnace and maintained at a 

 dull red heat for about an hour, being occasionally shaken. On 

 opening the crucible after cooling, it contains a blue mass of the 

 melted salt upon which rests a cake of metallic sodium. This 

 cake is broken into fragments and thrown into a liter flask con- 

 taining 500 cc of absolute alcohol cooled by ice. When the evo- 

 lution of hydrogen has ceased, the liquid is decanted and an 

 equal quantity of absolute alcohol is added. This washing is 

 continued until the alcohol shows no residue on evaporation. 

 The brilliant powder left behind is treated with absolute ether 

 and then dried in a stream of dry carbon dioxide or hydrogen. 

 It is preserved in a sealed tube. The yield is about 50 per cent 

 of the theoretical quantity, about 40 grams being obtained in 

 each operation. Crystallized metallic calcium may also be ob- 

 tained by electrolyzing fused calcium iodide at a red heat, the 

 negative electrode being pure nickel and the positive a graphite 

 cylinder placed in a porous cup. On analysis- the metal thus 

 obtained gave 98'9, 99*1 and 99*3 per cent of calcium in three 

 samples.— C. P., cxxvi, 1753-7, June, 1898. g. f. b. 



2. On the Preparation and Properties of Calcium Hydride. — 

 The direct union of calcium and hydrogen to form a hydride has 

 been effected by Moissax. The pure crystallized calcium above 

 described is placed in a nickel boat in a glass tube through which 

 passes a current of pure and dry hydrogen, prepared by passing 

 it successively through two red hot porcelain tubes, containing 

 copper turnings and pure boron respectively. The gas is then 

 dried by fused potash and phosphoric oxide calcined in a current 

 of oxygen. After the tube has been filled with hydrogen, the 

 end is sealed and the gas pressure is increased to 30 or 40 cm of 

 water. The temperature is then slowly raised and when it attains 

 a red heat the calcium takes fire ; the gas is rapidly absorbed and 

 a white fused mass of calcium hydride is obtained. It has a 

 crystalline fracture, a density of 1*7, and is not dissociated at 

 600° in a vacuum nor at the temperature of melting Bohemian 



