“ For the preparation of yttrium compounds the best raw material is gadolinite, which, according to König, consists of 22.61% of silica, 34.64 of yttria, Y2O3, and 42.75 of the oxides of erbium, cerium, didymium, lanthanum, iron, beryllium, calcium, magnesium and sodium. The extraction (as is the case with all the rare earths) is a matter of great difficulty. Metallic yttrium is obtainable as a dark grey powder by reducing the chloride with potassium, or by electrolysing the double chloride of yttrium and sodium. It decomposes water slowly in the cold, and more rapidly on heating. ”