Baskerville and Lockhart — Zinc Sulphide. 93 



Art. XI. — The Phosphorescence of Zinc Sulphide through 

 the Influence of Condensed Gases obtained by Heating 

 Rare-Earth Minerals ; by Charles Baskerville and L. B. 

 Lockhart. 



Helium has been shown to be a product of the disintegra- 

 tion of radium emanations ; it is also obtained from minerals 

 which contain thorium and uranium. It has been shown by 

 Afanassiew, Mine. Curie, Crookes, Strutt, Hoffman, Basker- 

 ville, and Boltwood that minerals containing these elements 

 are radio-active. 



It seemed to be of interest to ignite these minerals and con- 

 dense the gases given off and note their effect upon phospho- 

 rescent zinc sulphide. The method of procedure was essen- 

 tially that described in the preceding paper, except that the 

 pulverized mineral was placed in the closed tube of hard glass 

 instead of a radium preparation. Screens of Sidot's blende 

 were prepared in strips for the purpose. The glowing of the 

 screen was assumed to indicate the condensation of the emana- 

 tion. 



■ No final conclusion could be drawn from the experiments, 

 which were distinctly qualitative. It appeared, however, that 

 those minerals which offer the richest sources of helium gave 

 the greatest amount of emanation. Most of the minerals were 

 obtained by purchase, but we are indebted to Dr. Geo. F. 

 Kunz for some of them, to Dr. II. S. Miner, of the Welsbach 

 Lighting Co., for others, and to the Nernst Lamp Co., Pitts- 

 burg, Pa., for still others. 



In addition to the minerals we made some experiments with 

 uranium compounds*, commercial thorium oxide, and the frac- 

 tions of that element obtained in our laboratory. 



The list of minerals, and observations follow : 



Mineral. 



Locality. 



Result. 



Aeschynite 



Hittero, Norway 



Fair glow 



Allanite (orthite) 



Amherst Co., Virginia 



No glow 



Allanite 



Amherst Co., Virginia 



No glow 



Annerodite 



Norway 



No glow 



Auerlite 



Henderson, N. C. 



Fair glow 



Bastnasite 



Manitou Springs, Col. 



No glow 



Brookite 



Arkansas 



No glow 



Carnotite 



La Salle Creek, Mont. Co., 







Colorado 



Fine glow 



Carnotite 



Utah 



No glow 



Catapleiite 



Brevig, Norway 



No glow 



Cerite 



Bastnas, Sweden 



Fair glow 



Cleveite 



Moss, Norway 



Fine glow 



Columbite 



Amelia Co., Virginia 



No glow 



Crytolite 



Bluffton, Texas 



Faint glow 



with Fergusonite 



(Llano) 





*For which we are indebted to Dr. S. A. Tucker, Columbia University. 



