234 THE ATOMIC WEIGHTS. 



COLUMBIUM.* 



The atomic weight of this metal has been determined by Rose, Her- 

 mann, Blomstrand, and Marignac. Rosef analyzed a compound which 

 he supposed to be chloride, but which, according to Rammelsberg, J must 

 have been nearly pure oxychloride. If it was chloride, then the widely 

 varying results give approximately Cb = 122 ; if it was oxychloride, the 

 value becomes nearly 94. If it was chloride, it was doubtless contami- 

 nated with tantalum compounds. 



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

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

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

 bium as columbium pentoxide, and the chlorine as 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 : 



Cb.,0,. AgCl. 



591 -294 ..... 



.8085 .401 2.085 



633 .317 ..... 



.195 .0974 .500 



.507 .2505 1.302 



.9415 -472 2.454 



.563 .2796 ..... 



.9385 .4675 2.465 



.4788 .2378 



.408 .204 1.067 



9065 .45 1 5 



Hence the subjoined percentages, and the ratios 5AgCl : CbCl 5 : : 100 : x, 

 and 5 AgCl : Cb 2 O 5 : : 100 : x. 



*This name has priority over the more generally accepted " niobium," and therefore deserves 

 preference. 



fPoggend. Annal., 104, 439. 1858. 

 JPoggend. Annal., 136,353. r86g. 

 I Journ. fiir Prakt. Chem., 68, 73. 1856. 

 | Acta Univ. Lund. 1864. 



