134 Mr. A. S. Russell on the 



temperature may be due to a partial oxidation of the active 

 substance. Moreover, the very great volatility of the active 

 deposit of radium in sealed quartz tubes observed by Russell *, 

 as contrasted with the results of Makower t, is due to the 

 fact that the former had hydrogen in his tubes. This point 

 is treated by Mr. Russell in the following paper. 



Summary. 



1. The volatilization of actinium 13 deposited on platinum 

 has been measured in a high vacuum and has been found 

 to take place between 600° and y00°. 



2. By allowing chlorine, bromine, hydrobromic acid, and 

 hydriodic acid to act on the active material its volatility 

 ran be increased. 



3. The B and C products of the active deposits of radium, 

 thorium, and actinium condense in an atmosphere of hydrogen 

 at a temperature several hundred degrees lower than in air. 

 This has been explained by the formation of chemical com- 

 pounds. 



I wish to express my sincerest thanks to Prof. Rutherford 

 for suggesting these experiments and for his ever ready 

 advice and help. 



Physical Laboratories, 



University, Manchester. 



X. The I 'olatility of Radium C%. By Alexander S. Russell, 

 Carnegie Research Fellow of the University of Glasgow. 



THE interesting results described by Dr. Schrader in the 

 foregoing paper show clearly that the constituent ele- 

 ments of the radioactive deposits are capable of forming 

 chemical compounds. Dr. Schrader deals with the active 

 deposits of thorium and actinium. In this paper, which is 

 merely an appendix to his, the volatility of the radium active 

 deposit, is discussed. 



Makower § has shown that radium A, radium B, and 

 radium C cannot remain on a platinum surface when it is 

 heated in air to temperatures of 900°, 600°, and 1200° respec- 

 tivelj\ From a quartz surface the least volatile product of 



* Russell, Proc. Puw. Soc. A. vol. Ixxxvi. p. 276 (1912). 



t Makower, loc. cit. 



X Communicated by Prof. E. Rutherford, F.R.S. 



§ W. Makower, Manchester Memoirs, liii. No. 7 (1009). 



