46 
and Ta 2 0 5 , whilst the niobium chloride and oxychloride are 
represented respectively by the formulse NbCl 5 and NbOCl 3 . 
All the other supposed metals turned out to be either 
simple mixtures of these two in varying proportions, or such 
a mixture containing in addition some other metal, such as 
tungsten, titanium, or iron. 
Troost determined the vapour densities of niobium penta- 
chloride and oxychloride, obtaining the numbers 9 ’6 for the 
first and 7'87 for the second, agreeing closely with the cal- 
culated densities when the atomic weight of niobium is 
taken to be 94. 
Some time ago I obtained several crystals of Greenland 
columbite which possessed a specific gravity of 5 ’389 and 
which contains, as Marignac lias shown, little or no tanta- 
lum. From this material I prepared niobium pentoxide 
(Nb 2 0 5 ), niobium pentachloride (NbCl 5 ), and niobium oxy- 
chloride (NbOClg) by well known methods. 
I have likewise prepared metallic niobium and a new 
chloride of niobium. The results of these experiments are 
contained in the following communication. 
The following results of analysis of the pentachloride and 
oxychloride serve to show the purity of the material. 
Pentachloride. Oxychloride 
Niobium. . 
Calculated. 
....34-62 
Found. 
34-38 
Calculated. 
Niobium 43-42 
Found. 
42-93 
Chlorine . . 
.,..65-38 
65-55 
Chlorine 49-19 
49-34 
100-00 
99-93 
Oxygen (Diff.) 7 -39 
100-00 
7-73 
100-00 
Metallic Niobium is difficult to prepare, and precautions 
similar to those employed for the preparation of metallic 
vanadium must be taken. It is obtained as a bright steel 
grey shining metallic crust by passing the vapour of the 
pentachloride mixed with hydrogen repeatedly through a 
red-hot glass tube. The metafile crust then deposited on 
the side of the tube is next strongly ignited in a porcelain 
tube in a current of hydrogen until no further evolution of 
hydrochloric acid occurs. 
