Polonium, Radium, and Radioaetiniiim. 117 



11 mm., and its end EF is about 3 to 1 cm. from the end of 

 the porcelain tube. This inner cylinder can be kept cool, 

 when the outer is heated, by circulating cold water through 

 it, the water running in at Gr and out at E. A long tube of 

 quartz J passes through D and reaches almost to the bottom 

 of the porcelain tube. This enables the apparatus to be 

 tilled with hydrogen if required. The hydrogen passes out 

 of the tube through K. The active material deposited on a 

 metal was placed at B. The metal on to which it was to be 

 volatilized was wrapped round the cooled tube as high as 

 E'F'. A cap of the same material covered the end of the 

 tube EF. 



The tube ABC was placed in a furnace so that the tempe- 

 rature of three or four centimetres of it at the end B was 

 about 900°, the tube being water-cooled. The active plate 

 containing the polonium and the radium E was placed at B. 

 Aluminium was wrapped round the cooled tube. After two 

 hours the volatilization was stopped. It was then found 

 that the copper plate, now covered with a thin film of oxide, 

 was quite free from polonium and contained radium E only. 

 The aluminium, on the other hand, contained no radium E, 

 for it emitted very little /3-radiation and this did not decay 

 with time. The greater part of the polonium was deposited 

 on the cap which had been wrapped round EF. Some was 

 deposited on the portion E'EFF' in the vicinity of the end 

 of the tube. 



Many transference experiments were carried out in this 

 way with polonium. When small quantities were dealt with, 

 if the experiment were carefully carried out, there was 

 usually not much loss of material in volatilizing from one 

 metal to another, about 95 per cent, of material being ob- 

 tained on the second metal. It was more difficult to say 

 what proportion was obtained when large quantities were 

 used. 



In transferring radium E from one metal to another the 

 experiment was carried out similarly. Radium E was placed 

 at B, the same temperature was employed, but the volatili- 

 zation was conducted in a gentle stream of hydrogen gas. 

 The transference was never quantitative, but the loss of 

 material was rarely more than 10 per cent, of the whole. 



The <y-radiation of Polonium. 



The preparation of polonium deposited on aluminium foil 

 was mounted on a cardboard frame and suspended between 

 the pole-pieces of a powerful electromagnet. The faces of 

 the pole-pieces were 10 cm. X 16*5 cm. and were 7 cm. apart. 



