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THE ROYAL SOCIETY OF CANADA 



Table 5 — Feldspar 



Both substances gave a smaller effect when excited a second time. 

 This investigation yielded three results. 



1. Thermo-luminescence of calcite, Huorite and feldspar caused 

 -an increase in the electrical conductivity of these substances. 



2. When calcite was excited to thermo-luminescence more than 

 once, successive excitations produced smaller increases in the electrical 

 conductivity. 



3. Exposure to X-rays partially restored the crystal of calcite 

 to its original condition, so that the electrical effect of thermo- 

 luminescence was nearly as great as initially. 



For their valuable suggestions the writer thanks Drs. Bronson 

 and Johnstone. 



