A. S. Eve — Radium in Minerals by the ^-Radiation. 7 



containing the solutions. This precipitation would probably 

 have been avoided if some hydrochloric acid had been added 

 in the first instance. 



The preparation of standards is a difficult matter. Radium 

 is costly ; small quantities only are available ; it is difficult to 

 insure purity, while the weighing of small quantities is trouble- 

 some. It appears desirable to keep two radium standards, one 

 in the state of solution and the other in the solid state. The 

 two standards can be compared together by their 7-ray effects 

 from time to time. 



Summary. 



1. Radium E, which Rutherford proved to give /3-rays, 

 appears to give no 7-rays. More probably the 7-rays are 

 present, but like those of uranium they are weak and readily 

 absorbed. The very penetrating radiation from Joachimsthal 

 uraninite can be entirely attributed to radium C. 



2. Standard solutions of radium bromide, unless some acid 

 such as HC1 is present, attack or adhere to the glass of the 

 vessel in which they are contained, and become unreliable. 



3. It appears desirable to control the standard solutions by a 

 standard of solid radium bromide sealed in a test tube. 



4. Measurements of the radium present either in an ore, in a 

 solution or in any other form, whether made by the emanation 

 method or by the 7-ray test, are capable of giving concordant 

 results. 



5. A correction is necessary to the determination by Ruther- 

 ford and Boltwood of the ratio of the weight of radium to 

 that of uranium in radio-active minerals. The error in their 

 determination resulted from the radium standard altering in an 

 unexpected manner. 



McGill University, Montreal, April, 1906. 



