6 Makower, Volatility of Radiuvi A and Radium C. 



presence of radium B did not constitute a disturbing 

 factor in the experiments as this product is known to 

 volatiHse at a much lower temperature than radium C. 

 Measurements of the activity before and after heating 

 gave an estimate of the quantity of active deposit removed 

 during the heating. The measurements were made with 

 an a ray gold-leaf electroscope in the usual way. Care 

 was always taken to blow through the furnace to obviate 

 the possibility of any active deposit which had been 

 volatilised and remained in the furnace from being 

 redeposited. The results obtained with platinum, nickel, 

 and quartz plates are shown in the table. It will be seen 

 that in all cases the volatilisation begins between 700° 

 and 800° C, but that whereas with platinum and nickel it 

 is complete at I200°C., the volatilisation of radium C on 

 quartz surfaces is incomplete even at i30o"C. It thus 

 appears that the volatility of radium C is to some extent 

 dependent on the nature of the surface on which it is 

 deposited, the volatilisation temperature being higher for 

 a quartz than for a platinum or nickel surface. 



It is well known that the active deposit from radium can 

 be dissolved off a surface on which it has been deposited by 

 hydrochloric acid. It seemed of interest to see whether 

 the volatility of radium C was the same before and after 

 solution or whether by the action of the acid this product 

 had been chemically changed in such a manner as to be 

 more or less volatile. Although a considerable number 

 of experiments were carried out, no certain change in the 

 volatility of radium C after solution in hydrochloric acid 

 could be established. It always required, however, a 

 somewhat higher temperature to completely remove the 

 deposit from a quartz plate after solution in hydrochloric 

 acid than from a platinum plate. This is in agreement 

 with the observations mentioned above, with radium C 



