Intellige7ice and Miscellaneous Articles* 181 



charcoal and chlorine, is yellow, very fusible and volatile. Per- 

 chloride of niobium prepared in the same manner is colourless, non- 

 fusible, and but very slightly volatile. 



When dry ammonia is passed over perchloride of tantalum, the 

 gas is absorbed, but very slowly, and the perchloride becomes less 

 heated than is the case with the other liquid and volatile metallic 

 chlorides placed under the same circumstances. This is not owing 

 to the perchloride not possessing great affinity for the ammonia ; 

 but the new combination formed envelopes the perchloride of tan- 

 talum, and prevents the reaction from extending further. If this 

 new compound be heated, metallic tantalum is obtained, and hy- 

 droclilorate of ammonia disengaged. The whole of the hydrochlo- 

 rate of ammonia is removed by washing with water. On heating 

 the metal with access of air, it is converted into tantalic acid with 

 evolution of light. The reduction of tantalum requires a much 

 higher temperature than that of titanium under similar circum- 

 stances. Metallic tantalum presents the appearance of bhck crusts. 

 Water has no action on it. 



Perchloride of niobium submitted to the action of dry ammonia 

 becomes yellow, with considerable evolution of heat, because from 

 its being infusible it offers a greater surface to the action of the 

 ammonia. On applying heat to the new compound it immediately 

 becomes black, with disengagement of hydrochlorate of ammonia. 

 The reduction is effected at a much lower temperature than that of 

 the tantalum. On washing it with water to free it from hydrochlo- 

 rate of ammonia, the water passes clear as long as it contains any 

 of that salt ; but when the metal is nearly pure the water becomes 

 turbid. This inconvenience is avoided by adding a few drops of 

 alcohol to the water. When heated in the air the metal burns with 

 evolution of light into white niobic acid. Nitric acid and aqua rcgia 

 are without action on it even on boiling ; but it is attacked, with disen- 

 gagement of red vapours, by a mixture of nitric and hydrofluoric 

 acids. Tantalum behaves in the same manner towards these acids. 



If the same atomic composition be admitted for tantalic and 

 niobic acids, the weight of niobium will be higher than that of the 

 tantalum*. — From the Chemical Gazette for .Jan. loth, ISiS. 



ON THE CALCINATION OF HYDROUS OXIDE OF CHROMIUM. 

 BY M. KRUGER. 



It is well known that when hydrated oxide of chromium (Cr) is 

 heated to low redness in a platina crucible, it loses its water, 

 becomes strongly incandescent, and loses its solubility in dilute acids. 

 Several interesting circumstances have however remained entirely 

 unnoticed in this experiment. 



If hydrated oxide of chromium be heated only to a little above 

 392° F. in contact with the air, it loses all its water and becomes 

 almost black, it is however brown, when reduced to fine powder ; if 



* We are also informed by Mr. W. Francis that another new metal 

 called Rutheniuvi has recently been discovered in the platinum residues, by 

 Prof. Claus of Kasan. — R. T. 



