RECORDS. 301 



Central City, Colorado, caused the diamonds to phosphoresce. 

 It was further shown that if either kunzite (a variety of spodu- 

 mene), pectolite or wollastonite, pulverized, were mixed with 

 radium-barium carbonate, of 240 activity, the mixed powder 

 became permanently luminous. When these mixtures were 

 put in a Bologna flask and held on a metal plate, hot but not 

 showing any color, they immediately became very luminous and 

 remained so for a long time. Kunzite, pectolite and wollastonite 

 became phosphorescent by heating alone, the kunzite showing 

 an orange glow. When a kunzite crystal 5 cm. square and 5 

 cm. thick was exposed to the passage of an oscillating current, 

 the entire crystal glowed an orange pink, losing its lilac color, 

 a well-defined line through the center in the path of the current 

 being much more brilliant ; this phosphorescence lasted for 

 quite a time after exposure. Further experiments were made 

 with the same sensitive diamond mentioned above as to its tribo- 

 luminescence. Prints were obtained from negatives made by 

 laying the diamond face downward directly upon the photo- 

 graphic plate, and rubbing the back of the diamond with a stick 

 coated with wool, in one instance for a quarter of a minute, in 

 another for one half minute, the tribo-luminescence induced 

 causing the printing. The same type of diamond from British 

 Guiana, when heated on a metal plate below redness, phos- 

 phoresced distinctly, as also did pectolite and wollastonite. We 

 have here, therefore, luminescence of the tiffanyite body in 

 diamond, produced by radio-active pitchblende, by friction and 

 by heat. 



The paper by Dr. Davis was the first of a series of papers on 

 ** Recent Progress in Physical Science." Account was given of 

 Dr. H. A. Wilson's investigation of the distribution of electrical 

 intensity along the striated positive column, and his theory for 

 the electrical intensity in a uniform positive column. An outline 

 was also given of Professor J.J. Thompson's theory of the dis- 

 charge through Geissler tubes. Dr. Davis also reviewed Pro- 

 fessor J. S. Townsend's theory of the sparking potential^ 

 Professor Townsend having showed that the ionization is due to 

 impact of both positive and negative ions with the neutral mole- 



