Minerals containing Columbium, 411 



0*55 grain, (of paragraph 6) 1*78 grains of red oxide of 



manganese =s 1*6 gr. protoxide. 



Thus, the constituents of torrelite are, 



Columbic acid, .... 14-78 73-90 



Protoxide of iron, . . . 3*13 15 65 



Protoxide of manganese, . 1*60 8*00 



Water, 0-07 035 



19-58 97-90 

 To determine the atomic constitution of this mineral, we 

 must recollect, that the atomic weight of columbic acid is 

 25-75, of protoxide of iron 4*5, and of protoxide of man- 

 ganese 4-5. If we divide the preceding numbers by these 

 atomic weights we obtain. 



Atoms. 



Columbic acid, .... 2*87 or 1-6 

 Protoxide of iron, . . . 3*48 or 1-96 

 Protoxide of manganese, . 1*77 or 1* 

 These numbers leave no doubt, that the true constitution 

 of the mineral is, 



1 J atoms columbic acid 

 2 atoms protoxide of iron 

 1 atom protoxide of manganese 

 The atoms of the bases being twice as many as those of 

 columbic acid, we see that torrelite is composed of dicolum- 

 bates : and, as there are twice as many atoms of protoxide 

 of iron as of protoxide of manganese, it is obviously com- 

 posed of 



2 atoms dicolumbate of iron 

 1 atom dicolumbate of manganese 

 So that the formula indicating its constitution is, 2/2 .q\ 

 •f mn^ CI. 



2. Columhite. 



The name columhite^ given by Mr. Hatchett to the original 

 specimen in the British Museum, may with propriety be 

 applied to the Bohemian specimens ; because, there are 

 strong reasons for considering the constitution of both as 

 very nearly alike.* I do not know who was the discoverer 

 of it at Bodenmais, in Bohemia. But as I have already 

 mentioned, I got a specimen of the Bohemian columbitc 



• This, indeed, has already been done by M. Gustav Rose. 



