1 54 Intelligence and Miscellaneous Articles. 



Probably tungsten, molybdenum, silicium, aluminum, &c. may be 

 reduced in the same way. — Ann. de Chim. et de Ph. vol. xlvii. p. 108, 



nEDUCTION OF CHROMIUM. BY THE SAME. 



When a current of dry ammoniacal gas is passed over the chlo- 

 ride of chromium and ammonia, heated to redness in a glass tube, it 

 is perfectly decomposed, and black pulverulent metallic chromium is 

 obtained, which acquires the metallic lustre under the burnisher j 

 it burns at a red heat, and is converted into a brown powder. 



When ammoniacal gas is passed into chloride of chrome, the com- 

 bination sometimes occurs with the disengagement of light, the 

 vessel is filled with a purplish-red flame, which continues until the 

 chloride of chromium is entirely saturated. 



Metallic chromium is obtained in a still simpler mode, by redu- 

 cing chloride of chromium with ammonia, under the same circum- 

 stancesj but then the metal, instead of being black, is of a chocolate- 

 brown colour. 



The preparation of chloride of chromium is so well known, that 

 it would appear superfluous to say more respecting it, if it were not 

 in itself a subject of so much interest. 



When a neutral solution of muriate of chrome is evaporated, a 

 green mass is obtained, which undergoes no change, and does not 

 yield water at some degrees above 212^. It swells at a temperature 

 of from 400^ to 570°, and is converted, by losing its water, into a bril- 

 liant, spongy, crystalline mass of a peach-blossom colour. This 

 mass does not sublime, as usually supposed, for it is not at all vola- 

 tile. The conversion of a muriate into a chloride cannot be shown 

 in so convincing a manner with any other compound. 



By calcining the chloride in contact with the air, the oxide of 

 chromium is usually obtained of so fine a colour, that this method 

 of preparing it for porcelain painting may be advantageously em- 

 ployed. If Frik's method be employed, it is sufficient to evaporate 

 the muriate without precipitating it, and without calcining the dried 

 salt. By passing sulphuretted hydrogen gas over heated chloride 

 of chromium, crystalline sulphuret of chromium is obtained of a 

 brilliant black colour. 



Metallic chromium, prepared in the method above described, 

 burns in the air during calcination, but it does not become green ; 

 the oxide thus obtained was not examined as to whether it differed 

 in composition from common green oxide. — Ibid. 



MR. AUDUBON S SCIENTIFIC EXPEDITION. 



We are requested to state that information of the progress of 

 Mr. Audubon the naturalist will be given to the scientific world, 

 from time to time, in the columns of Mr. Featherstonhaugh's Jour- 

 nal of Geology, published at Philadelphia*. He has already passed 

 through Virginia on his way to Florida, accompanied by an assistant 

 draughtsman and a collector. 



• See Phil. Mag. and Annals, N.S. vol. x. p. 315. 



The 



