ATOMIC WEIGHTS 335 



COLUMBimi/ 



The atomic weight of this metal has been determined by several in- 

 vestigators. Eose "^ analyzed a compound which he supposed to be chloride, 

 but which, according to Eammelsberg," must have been nearlv pure o.\y- 

 chloride. If it was chloride, then the widely varying results give ap- 

 proximately Cb = 122; if it was oxychloride, the value becomes nearly 

 94. If it was chloride, it was doubtless contaminated with tantalum 

 compounds. 



Hermann's * results seem to have no present value, and Blomstrand's ' 

 are far from concordant. The latter cliemist studied columbium penta- 

 chloride and sodium columbate. In the first case he weighed the colum- 

 bium as columbium pentoxide, and the chlorine a? silver chloride, the 

 oxide being determined by several distinct processes. In some cases it 

 was thrown down by water, in others by sulphuric acid, and in still 

 others by sodium carbonate or ammonia jointly with sulphuric acid. 

 The weights given are as follows : 



Hence the subjoined percentages, and the ratios oAgCl : CbCl-, : : 100 : .r, 

 and 10AgCl:Cb2O,::100:ar; 



■■^ This name has forty years priority over " niobium, " and therefore deserves preference. 

 ^'Pogrgend. Annal., 104, 439. 1858. 

 ^Pogrgend. Anna!., 136, 353. 1869. 

 ^ Joiirn. prakt. Chem., 68, 73. 1856. 

 ' Acta Univ. Lund, 1864. 



