Minerals containing Columhium. ' 415 



while columbite consists of 2 atoms columbic acid united to 



3 atoms of the same bases. 



Dr. Wollaston analyzed 5 grains of the original specimen 



of columbite in the British Museum, and obtained, 

 Columbic acid, .... 4* or 80 

 Protoxide of iron, . . . 0*75 15 

 Protoxide of manganese, 0-25 5 



5-00^ 100 

 This approaches pretty nearly to my analysis. We cannot 

 expect minute accuracy in an analysis conducted on so 

 small a scale. But it is near enough, I conceive, to leave 

 no doubt about the identity of the columbite in the British 

 Museum and that found at Bodenmais. This is farther 

 corroborated by the specific gravity of the British Museum 

 specimen, vrhich Mr. Hatchett found to be 5'918. 



3. Tantalite. 



The specimens of tantalite from Finland, by the examina- 

 tion of which Ekeberg discovered the metallic substance 

 to which he gave the name of tantalum, were sent him by 

 M. Geyer ; and it is not accurately known from what part 

 of Finland they came. Berzelius conjectures that they 

 had been found at Skogsbole, in the parish of Kimito, 

 where an attempt had been made to obtain tin, for the 

 oxide of which tantalite had been taken. At Ekeberg's 

 death, his mineral collection was purchased by Dr. Mac- 

 michael, who was liberal enough to give to Berzelius all 

 the specimens of tantalite which it contained. One of 

 these consisted of a small piece, labelled by Ekeberg as 

 having a specific gravity of 7*236. The rest had been 

 reduced to powder, obviously for analysis 



Berzelius gives no description of this tantalite, and the 

 quantity of it was so small, that he was able to use only 

 one gramme or 15*433 grains ; and, though some anomalies 

 occurred in the analysis, it was not in his power to remove 

 them by repeating it. Klaproth obviously employed the 

 same mineral in his analysis of tantalite. He gives the 

 following short description of it : 



Colour, iron black, amorphous. Lustre, semi-metallic, 



^ Phil. Trans. 1809, . p. 248 



