Baslcerville — Ultra- Violet Light upon Earth Oxides. 465 



Akt. XLY. — Actio7i of Ultra- Violet Light upon Bare Earth 

 Oxides ^ bj Charles Baskeeville. 



During the extended investigations of the action of ultra- 

 violet light, cathode rays, Eontgen rays, and the emanations of 

 radinm upon gems and minerals in the Morgan-Tiffany gem 

 and Morgan-Bement mineral collections in the American 

 Museum of I^atural History, a number of rare earth oxides 

 were subjected to the action of ultra-violet liglit.* The follow- 

 ing oxides were exposed to ultra-violet light produced by a 

 Piffard lamp : 



Gadolinium oxide (prepared by Waldron Shapleigh).-)- 



Lanthanum oxide (prepared by H. S. Miner). 



IN'eodidymium oxide (prepared by a method of Baskerville 

 and Stevenson). 



Praseodidymium oxide (prepared by the method of Basker- 

 ville and Turrentine). 



Cerium oxide (prepared by H. S. Miner). 



Samarium oxide (prepared by Waldron Shapleigh). 



Thorium dioxide (chemically pure according to general 

 acceptation previous to 1900, prepared by Baskerville and 

 Davis). 



Yttrium oxide (prepared by Waldron Shapleigh). 



Yttrium, erbium, and ytterbium oxides mixed (prepared by 

 H. S. Miner). 



Erbium oxide (bought from Kahlbaum). 



Erbium group oxides (prepared by Benton Dales). 



Uranium oxide (prepared by S. Auchmuty Tucker). 



Uranium oxide (prepared by S. Auchmuty Tucker). 



Yttrium oxide (prepared by Dennis and Dales). 



Ytterbium oxide (prepared by Benton Dales). 



Titanium dioxide (bought from Eimer and Amend). 



Zirconium dioxide (prepared by Yenable and Baskerville). 



Only two of the above oxides responded at all to the action 

 of ultra-violet light, namely, zirconium and thorium dioxides, 

 which phosphoresced strongly. The thorium dioxide remained 

 luminous in the dark for a greater length of time. The zir- 

 conium dioxide showed no radio-activity when tested by the 

 electrical and photographic methods. It is strange that the 

 two rare earths forming normally the dioxide are the only 

 ones to exhibit this property. This will be investigated 

 further. 



* Reported to New York Academy of Sciences, Oct, 6, -1903. 

 f My thanks are due to Doctors Miner, Tucker and Dales for the generous 

 loan of preparations. 



Am. Joub. Sci.— Fourth Series, Vol. XVI, No. 96. — December, 1903. 

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