192 Scientific Intelligence. 



yellow color.) A piece of calcium reacts slowly with water 

 on account of tbe difficult solubility of the hydroxide, but if 

 a little hydrochloric acid is added, the evolution of hydrogen 

 is violent. A sample of the commercial metal was found 

 to contain 0*2 per cent of silicon and 0*3 per cent of aluminium 

 with traces of iron. The hydrogen produced from it was very 

 pure, and contained no appreciable amount of acetylene or 

 other hydrocarbons. The specific gravity of the metal was 

 found to vary considerably in different samples ; a very pure 

 specimen gave 1*52 as the result. In this investigation the melting- 

 point was not very exactly determined, but it was near 800°. The 

 metal begins to vaporize in a vacuum below its melting-point, and 

 forms beautiful crystals which are free from silicon and aluminium. 

 The vapor of calcium reacts very energetically — much more so than 

 magnesium — with any residue of air that may be in the tube in 

 which it is heated. In this way a very complete vacuum may be 

 obtained from an imperfect one. — Berichte, xxxvii. h. l. w. 



3. The Use of Dried Air in Blast-furnaces. — The employment 

 of air dried by refrigeration, a process due to Mr. Gailey and 

 applied at the Isabella Furnaces near Pittsburgh, has received 

 considerable attention of late in the technical journals. The 

 advantage attributed to the removal of the moisture from the air 

 used for blast depends upon the fact that water is decomposed by 

 incandescent carbon with the absorption of heat, and with the 

 direct loss of carbon, by the reaction 



C + H 2 O^CO + H 2 , 



and it is claimed that a gain of 20 per cent is made in the effi- 

 ciency of the fuel. 



The process has been recently discussed by Le* Chatelier, in 

 France, from a scientific point of view, and he maintains that the 

 gain in efficiency attributed to the process is about four times 

 greater than the theoretical maximum obtained by calculation. He 

 puts forward the view that the advantage is partly due to a 

 possible effect of the dryness of the air upon the removal of the 

 sulphur from the pig-iron, and supports this opinion by the results 

 of experiments in which it was found that dry carbon monoxide 

 free from hydrogen does not remove sulphur from heated calcium 

 sulphide, while the gas when mixed with hydrogen removes it 

 with considerable rapidity. — Comptes Benches, exxxix, 925. 



h. l. w. 



4. Trisulphoxy arsenic Acid. — McCay and Foster have pre- 

 pared the salts 



Na 3 AsOS 3 'llH 2 0, 

 NaSrAsOS 3 -10H 2 O,. 

 Ca 3 (AsOS 3 ) 2 .20H„O, 

 K 3 AsOS 3 -7H 2 0, and 

 KBaAsOS 3 -7H 2 0, 



which represent a heretofore missing member, H 3 AsOS 3 , of a series 

 of acids intermediate between H 3 As0 4 and H 3 AsS 4 , concerning 



