The Curies 67 



vessel was seen to register constantly 5*4 degrees Fahren- 

 heit higher than the latter. 



He also showed how the yellow powder of zinc sulphide 

 bursts into a brilliant glow under the stimulus of radium 

 emanation. It was through this experiment that Sir 

 William Crooks devised his spinthariscope, which allows 

 one actually to see radium breaking up and flinging off a 

 never-ceasing shower of atoms in a myriad of tiny blazing 

 stars. 



M. Curie also proved that all substances may be ren- 

 dered radio-active by being exposed to the emanation of 

 radium. Lead, rubber, wax, celluloid — fifty substances 

 in all — were so tested. Another very interesting point he 

 made was that radium provides an easy means of dis- 

 tinguishing real diamonds from imitations, since it causes 

 the real stones to glow with a brilliant phosphorescence, 

 while the sham stones remain unaffected. 



A result of these new discoveries was that in 1904 a 

 new position was created specially for M. Curie at the 

 Sorbonne, and his clever wife was appointed " chief of 

 staff " under him. The post carried a fair salary, and for 

 the first time in their lives these two hard-working 

 geniuses found themselves comfortably off. They already 

 had one daughter, and now a second was born, and for a 

 time their life was both busy and happy. 



Then came disaster. On a day in 1906 Pierre Curie 

 went out to lunch with a few intimate friends. He was 

 very gay and happy, for, as he told them at lunch, he was 

 now going to give up teaching and to devote all his time 

 to research. He left his friends and started homeward on 

 foot. As he crossed the crowded street he was knocked 

 down by a carelessly driven dray and killed on the spot. 



Poor Mme Curie suffered terribly, but she was too 

 strong a character to succumb altogether, and after a 

 time she went back to the laboratory and to work. She 

 told her friends that while life remained to her she would 



