88 EXPERIMENTS WITH RONTGEN RAYS, ETC. 



example. It had been found that certain of these fluorescent or 

 phosphorescent substances had a peculiar connection with the 

 " X " rays, and that when the " X " rays fell upon them they at 

 once became brightly illuminated, and anything which was 

 opaque to the rays, on being placed in the back of the screen, 

 caf?t a shadow on it. Thus observers were able to see at once 

 the bones of the hand, coins in a book, &c. The screen Mr. 

 Sutton had succeeded in making was after the method of Edison, 

 he having used tungstate of calcium to coat the screen with. 



Having thus explained the apparatus, Mr. Sutton made 

 several exposures of plates with remarkably good results. One 

 interesting exposure was a collection of various articles, offering 

 various degrees of opacity to the rays. The development of the 

 plates was admirably carried out by Mr. Ferguson under circum- 

 stances decidedly unfavourable to such delicate work, with capital 

 results. The exhibition of articles on the fluorescent screen, 

 where the wonderful effects of the " X " rays were at once visible, 

 called forth frequent applause. Coins placed in a cigar case were 

 plainly seen, and so were similar articles placed between two-inch 

 thick deal boards, or in the middle of a thick book. Neither the 

 wood nor the paper seemed to offer much resistance to the light. 



The proceedings were terminated by a hearty vote of thanks 

 to the lecturer and demonstrator. 



