Baskerville and Kunz — Rare Earth Oxides. 79 



Art. VI. — Effects on Rare Earth Oxides produced by 

 Radium- Barium Compounds and on the Production of 

 Permanently Luminous Preparations by Mixing the 

 Latter with Powdered Minerals / by Charles Basker- 

 ville and George F. Kunz. 



The following rare earth oxides in powdered condition were 

 mixed with radium-barium chloride of 240 activity. The 

 mixture was shaken in test tubes and carefully observed in 

 the dark to note any luminosity. None was observed with 

 any one of the oxides. The following oxides were used : 

 thorium, zirconium, titanium dioxides; zinc, cerium, lantha- 

 num, yttrium, ytterbium, erbium, a mixture of the last three, 

 praeseodidymium, neodidymium, lanthanum, gadolinium, sama- 

 rium and uranium oxides.* They were not examined with a 

 microscope, although a magnifying glass was used. 



Berthelotf compared certain specific chemical reactions 

 caused by light and an electric current with those provoked by 

 radium. He noted that the work is tedious on account of the 

 small quantities of radium to be used and the necessity for 

 working in glass envelopes, which absorb part of the rays and 

 in certain cases probably the most efficient portion. M. and 

 Mme. Curie noted that various chemical effects produced by 

 radiations from radium were similar to light. BecquerelJ 

 extended the examination with a sealed glass tube enveloped 

 in aluminum foil. Glew§ gives a random list of substances 

 which fluoresce, and some which do not, when submitted to 

 the action of radium bromide within a glass container and sur- 

 rounded by black paper. Crookes' spinthariscope || is an instru- 

 ment for showing the luminescent effect produced upon a 

 Sidot's blende screen by exposed radium salts. Elster and 

 Geitel^f independently observed the luminosity produced by 

 the bombardment of radium " electrons " and showed the 

 difference between phosphorescence produced by emanation 

 and that produced by illumination. We have not, however, 

 learned of any experiments where pulverized materials, mineral 

 and chemical preparations, have been mixed directly with 

 radium-barium compounds of different composition and activi- 

 ties in this manner. 



We** have mixed pulverized chlorophane, willemite, zinc 

 oxide (made by the French process), zinc sulphide, and 



* The sources of these oxides are given in a previous paper. This Journal, 

 Dec., 1903, p. 465. 



f Compt. Eend. , cxxxiii, 659. % Compt. Eend. , cxxxiii, 709 (1901). 



§ Nature, July 2, p. 3, 1903. | Chem. News, lxxxvii, 241. 



If Physik. Zeitschr., iv, 15, 439. ** Trans. N. Y. Acad. Soi., Oct. 6, 1903. 



