II. On scandium

Abstract

Scandia is one of the rarest and least known of the recognised rare earths. It was discovered in 1879 by Nilson, who separated it, with ytterbia, from erbia extracted from euxenite and gadolinite. Nilson made an incomplete chemical examination of some of its compounds, but owing to the inadequate amount of material at his disposal he did not at first entirely separate it from ytterbia. Later in the same year Cleve extracted scandia from gadolinite, yttrotitanite, and keilhauite, and described the scandium sulphate, double sulphates, nitrate, oxalate, double oxalates, selenate, acetate, formate, oxide, and hydrate, and gave some of the chief reactions of the new body. Cleve, working on gadolinite, found that it contained only from 0·002 to 0·003 percent, of scandium, while keilhauite yielded only about 0·005 per cent. He gave results from which he deduced an atomic weight of about 45. Cleve noticed that scandium almost exactly corresponded to the description given by Mendeleeff of his hypothetical element “ekaboron,” of atomic weight 44. More recently, in 1880, Nilson, working on somewhat larger quantities of scandia, described and analysed the nitrate, sulphate, selenate, oxalate, and the potassium double sulphate. He found the atomic weight to be 44·03, the mean of four separate and closely concordant determinations. Taking Nilson’s data, and re-calculating from them the atomic weight of scandium, using the most recent figures for oxygen and sulphur, I find his atomic weight to be almost exactly 44·1—a figure I have used in the following paper.