664 A Comparison of Radium Standard Solutions. 



radium bromide solution deteriorates with boiling, and that 

 because of this, too great reliance cannot be placed on the 

 result of a single test. Every solution tested showed a steady- 

 decline, even after adding the acid. In all, about 70 tests 

 were made. 



A similar solution was prepared and used by Dr. Eve in 

 Nov. 1908. This was also tested, and showed only 45 per cent. 



of the strength obtained for the Washington sta ndard. It thus 



... 

 appears that such solutions, which have been boiled a number of 



times and then allowed to stand very long, are not reliable, and 



a new preparation should be used for each set of experiments. 



This work showed that the weak solution of the Rutherford- 

 Boltwood standard is to the Washington standard solution in 

 the ratio of 98 : 100. The results obtained in the comparison 

 of the strong and the weak solutions of the Rutherford- 

 Boltwood standard showed the strong 2 per cent, lower than 

 the weak, or strong : weak : : 98 : 100. This may be con- 

 sidered fair agreement, and indicates but slight deterioration 

 with time. We thus have 



Rutherford-Boltwood, strong solution : Washington = 96 : 100 

 Rutherford-Boltwood, weak solution : Washington = 98 : 100 



A more complete set of experiments will be carried out later, 

 and the exact effect of successive boilings further determined. 



In closing, the writer has much pleasure in expressing his 

 appreciation for suggestions given by Professor Eve, and 

 also by Dr. Mcintosh, in the course of this work. 



Summary. 



1. The object of this work was to determine the accurate 

 value of the Rutherford-Boltwood standard solution at McGill 

 University, by comparison with the Washington standard 

 solution. The former was compared initially with the 

 Rutherford-Boltwood solid standard, which is known to be 

 4*9 per cent, too low on the International. If no errors 

 were made in their preparation, we should expect the solu- 

 tion standards to come out similarly. This work shows fair 

 agreement — about 3 per cent, low, whereas the solid standard 

 is 4*9 per cent. low. 



2. The strong and the weak solutions of the Rutherford- 

 Boltwood standard, prepared in the ratio of 100 : 1, turn out to 

 be in fairly good agreement — probably within 2 per cent. This 

 shows that no serious deterioration has occurred with time. 



3. It has been found that a radium bromide solution 

 deteriorates with each boiling. Also that if a sufficient 

 amount of hydrochloric acid, free from radioactive matter, 

 is added, the solution will recover its normal emanating 

 power. The cause of this has not yet been ascertained. 



Montreal, May 22, 1915. 



