Paper, 'On some new elements in gadolinite and samarskite, detected spectroscopically' by William Crookes Crookes writes: 'The recent discovery by my distinguished friend M. de Boisbandran on the existence of a new element which he calls Dysprosium makes it unadvisable on my part, as a fellow investigator in spectroscopic research, to delay any longer the announcement of some of the results I have obtained during the fractionations of the samarskite and gadolinite earths. I will first take the earths which give absorption-spectra when their solutions are examined by transmitted light. These occur chiefly at the higher end, beginning with didymium and proceeding, through samarium, holmium, &c., to erbium, which is one of the least basic. The earths which give phosphorescent spectra chiefly occur at the lower end, but each group overlaps the other; for instance yttria occurs above erbia.' Annotations in pencil and ink. Includes one diagram of spectra. Subject: Spectroscopy / Mineralogy Received 8 June 1886 / 9 June 1886. Read 10 June 1886. A version of this paper was published in volume 40 of the Proceedings of the Royal Society as 'On some new elements in gadolinite and samarskite, detected spectroscopically'. 1886