74" URANIUM, ANTIMONY, CHROMIUM, &c. 



Both Hatchett and Ekeberg had tried unsuc- 

 cessfully to reduce the oxide of columbium to 

 the metallic state. But Berzelius, Gahn, and 

 Eggertz, were more successful in the year 1815 ; 

 and Berzelius, in the fourth volume of the Af- 

 handlingar, published a detailed account of the 

 properties of this metal, and the result of a set 

 of experiments to determine the proportion of 

 oxygen with which it unites in order to be con- 

 verted into the white oxide, to which Hatchett 

 gave the name of columbic acid. 



After these introductory remarks, I shall pro- 

 ceed to relate the experiments which I have 

 made in order to determine the atomic weight of 

 columbic acid. 



* 162 grains of oxide of columbium, which 

 j na( j procured from the Finland mineral called 

 tantalite, was fused in a platinum crucible with 

 six times its weight of anhydrous carbonate of 

 soda : water was poured upon the fused mass to 

 soften it, and the crucible having been inadver- 

 tently left on the sand bath till the water was 

 driven of I found the whole matter converted 

 into large, white, opaque prismatic crystals. The 

 quantity of salt and oxide having been too great 

 for the size of my crucible, I had been obliged 

 to divide it into two portions. After the first 

 portion had been washed out of the crucible, I 

 repeated the fusion with the second portion the 

 fused mass was digested with water, and the 



