568 Reports and Proceedings — The Roycd Society. 



I. — The Royal Society. 

 Novemher 5, 1914. 



1. " On Acquired Radio- Activitv." By Sir "William Crookes, O.M., 

 LL.D., D.Sc, Pres.R.S. 



Various objects, diamond, ruby, garnet, quartz, gold, platinum, 

 etc., also the phosphorescent substances yttria, calcium sulphide, zinc 

 blende, and barium platinocyanide, are bombarded in a high vacuum 

 by cathode rays, and in no case can any permanent activity be 

 recognized either by photographic or electrical means. 



Exposure to radium emanation confers temporary radio-activity on 

 all bodies that have been tried, apparently due to the condensation 

 of the emanation on the surface. This transient activity can be 

 completely removed by washing in dilute acids. 



Many substances become coloured by direct exposure to radium, the 

 colour depending on the substance. Diamond takes a full sage-green 

 tint, the depth of tint depending on the time of exposure to the radium. 



In addition to change of colour diamond also becomes persistently 

 radio-active, continuously giving off a-, yS-, and 7-rays. The acquired 

 colour and activity withstand the action of powerful chemical agents, 

 and continue for years with apparently undiminished activity. 



Removing the surface by mechanical means removes both colour 

 and radio-activity. 



The appearance of an auto-radiograph made by placing an active 

 diamond crystal on a sensitive photographic plate, and the visual 

 examination of its ' scintillation ' luminosity, suggest that there is 

 a special discharge of energy from the corners and points of the crystal. 



2. Medals for Research. 



The King has approved of the following awards this year by the 

 President and Council of the Royal Society : — 



A Royal Medal to Professor Ernest W. Brown, F.R.S., for his 

 investigations in astronomy, chiefly in the Lunar Theory. 



A Royal Medal to Professor William J. Sollas, E.R.S., for his 

 researches in palaeontology, especially in the development of new 

 methods. 



The following awards have also been made by the President and 

 Council : — 



The Copley Medal to Sir Joseph Thomson, O.M., F.R.S., for his 

 discoveries in physical science. 



The Rumford Medal to Lord Rayleigh, O.M., E.R.S., for his 

 numerous researches in optics. 



The Davy Medal to Professor "William Jackson Pope, F.R.S., for 

 researches on sterochemistry and on the relations between crystalline 

 form and chemical constitution. 



The Darwin Medal to Professor Edward B. Poulton, E.R.S., for his 

 researches in heredity. 



The Hughes Medal to Professor John S. Townsend, F.R.S., for his 

 researches on electric behaviour of gases. 



