Spectrophotometric determination of dysprosium, holmium, erbium, thulium, and ytterbium

The transmittancies of solutions of the nitrates of dysprosium, holmium, erbium, thulium, and ytterbium were measured, over the range 350 to 1,000 ml', by means of a double-monochromator photoelect ric spectrophot omet er. Terbium and yttrium show no appreciable absorption in this range. The bands found most suitable for determination of the fiv e elements are: for dysprosium, at 910 mIL; for holmium, at 643 ml'; for erbium, at 521 ml' and 653 mIL ; for thulium, at 684 mIL; and for ytterbium, a t 950 ml' and 973 mIL.