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' 
XV. On the Identity of Columhium and Tantalum . By Wil- 
liam Hyde Wollaston, M. D, Sec. R. S. 
Read June 8, 1809. 
W ithin a short time after the discovery of columbium by 
Mr. Hatchett in 1801,* a metallic substance was also dis- 
covered in Sweden bV M. Ekeberg,'!' differing from every 
metal then known to him ; and accordingly he described the 
properties by which it might be distinguished from those which 
it most nearly resembled. But although the Swedish metal 
has retained the name of Tantalum given to it by M.Ekeberg, 
a reasonable degree of doubt has been entertained by che- 
mists, whether these two authors had not in fact described 
the same substances ; and it has been regretted that the disco- 
verers themselves, who would have been most able to remove 
the uncertainty, had not had opportunities of comparing their 
respective minerals, or the products of their analyses. 
As I have lately obtained small specimens of the two Swe- 
dish minerals, tantalite and yttro-tantalite, from which I could 
obtain tantalum, and was very desirous of comparing its 
properties with those of columbium, Mr. Hatchett very 
obligingly furnished me with some oxide of the latter, which 
remained in his possession. 
* Phil. Trans, for 1802. 
-J- Vetenkaps Academiens Handlingar. 1802, p, 68 .—Journal des Mines, V ol. XII. 
p. 245. 
