126 Scientific Intelligence. 
6. On Niobium.—H. Rose has published in part, the resul 
long continued and elaborate investigations of niobium an 
pounds—investigations which may justly be considered as among U 
most difficult and tedious which chemists have ever undertaken. — 
ts of 
its col 
Metallic niobium is most easily prepared by heating the double fiuorids 
or hypofluorids of niobium: and the alkaline metals with sodium to” 
of oxydation of niobium which is lower than hyponiobic acid. - 
acid does not dissolve niobium even on heating. Concentrated sulphur 
acid dissolves metallic niobium by long heating, the solution has a brow 
ish color and gives a brownish precipitate with ammonia. Filuohyt! 
acid also dissolves niobium, and the solution is effected still more exsilf 
oxydation of niobium yields only hyponiobie acid NbaOs, and not niobit A 
acid NbOs, so that in this respect the metal differs from tantalum. 
density of the metal obtained from the fluorids was 6-297; of that ? 
melts at 212° C., and solidifies sooner than the chlorid of tantalum, ¥™ 
- fuses at a rather higher temperature. Rose made repeated analyse 
the chlorid of niobium, decomposing it with water, and determining © 
chlorine and niobic acid produced. These analyses from the extreme’ 
of the subject did not yield results which correspond as accu” 
could ired.. The author rejects the results of the first! 
