ONE HUNDRED YEAKS OF CHEMISTRY 311 



fact that, like uranium, it is radio-active, decomposing 

 spontaneously into other elements. 



Vanadium had been encountered as early as 1801 by 

 Del Rio, who named it " erythronium, " but a little later 

 it was thought to be identical with chromium and was lost 

 sight of for a while. In 1830, however, it was re-discov- 

 ered by, and received its present name from Sefstrom in 

 Sweden. Berzelius immediately made an extensive 

 study of vanadium compounds, but he gave them incor- 

 rect formulas and derived an incorrect atomic weight for 

 the element, because he mistook a lower oxide for the 

 element itself. Roscoe in England in 1867 isolated 

 vanadium for the first time, found the right atomic 

 weight, and gave correct formulas to its compounds. 

 Vanadium is particularly interesting from the fact that 

 it displays several valencies in its compounds, many of 

 which are highly colored. It has found important use as 

 an ingredient in very small proportions in certain 

 ''special steels" to which it imparts a high degree of 

 resistance to rupture by repeated shocks. 



Columbium was discovered early in the nineteenth 

 century in the mineral columbite from Connecticut by 

 Hatchett, an Englishman, who did not, however, obtain 

 the pure oxide. It was afterwards obtained by Rose who 

 named it niobium. Both names for the element are in 

 use, but the former has priority. Attention was called 

 to this fact by an article in the Journal by Connell, an 

 Englishman (18, 392, 1854). 



The Platinum Group of Metals. In 1854 a new mem- 

 ber of the platinum group of metals, ruthenium, was dis- 

 covered by Claus. Platinum had been discovered about 

 the middle of the eighteenth century, while its other rarer 

 associates, iridium, osmium, palladium, and rhodium, had 

 been recognized in the very early years of the nineteenth 

 century. It was during the latter period that platinum 

 ware began to be employed to a considerable extent in 

 chemical operations, and this use was greatly extended 

 as time went on. The discovery was made by Phillips 

 in 1831 that finely divided platinum by contact would 

 bring about the combination of sulphur dioxide with 

 atmospheric oxygen, and this application during the past 

 20 years has become enormously important in the sul- 



