88 THE NEW KNOWLEDGE. 



substance was employed. Any substance containing ura~ 

 nium gave off the rays. Metallic uranium itself, obtained 

 in Moissan's electric furnace, gave out more rays than any 

 of its compounds. More than that, the emission of the 

 rays turned out to be altogether independent even of phos- 

 phorescence. Uranium bodies, whether phosphorescent or 

 not, emitted rays. Here, then, was no stored up, trans- 

 formed sunlight, such as Niewenglowski's rays, but pene- 



Fig. 22. Uranium radiograph. 



trating, continuous emissions from a substance having no 

 relation to light. The emission of rays capable of passing 

 straight through copper from a chemical substance in its 

 normal condition constituted to us a new property of matter 

 a new thing in nature. 



So, as Becquerel stood in his laboratory that night, with 

 this thought in his mind and the plate in his hand, he ap- 

 pears sharply silhouetted against the background of the ages; 

 he is comparable with that Theophrastus who, two thousand 



