196 Hon. K. J. Strutt. On the Radio-activity of [Feb. 29, 



Material. 



Quantity 

 taken in 

 grammes. 



Rate of 

 leak 



due to 

 emanation 



(sc. div. 

 per hour). 



Rate of 

 leak 



due to 

 emanation 

 1 1 om iuu 

 grammes. 



Time in 

 days taken 



by the 

 emanation 

 to fall to 

 nan us 

 initial 

 value. 



lung s oprmg, jjatri — 













1 A 



OKA 



2,500 



O .£!A 

 O DO 





1 L 



/o Z 



DOU 







18 



12-4 



69 



•• 



Old Royal Spring, Bath — 











Deposit from channel near well . 



10 



63 -5 



635 





„ bottom of tank . . . 



15 



60 



400 





Hard deposit from sides of tank . . 



25 



43 



173 



3-58 



1 



26 



356 



1,370 



3-81 



seemed sufficient to prove that the activity was really due to radium, 

 yet it was thought desirable to show that the chemical properties 

 of the active constituent were in agreement with this conclusion. Two 

 hundred grammes of the richest deposit were treated with dilute 

 sulphuric acid. The activity was all in the insoluble residue, which 

 was dirty white in colour, and amounted to about half of the entire 

 quantity of deposit. The residue was boiled with strong sodium 

 carbonate solution. This was washed away, and the mass extracted 

 with hydrochloric acid. The hydrochloric acid solution gave a slight 

 precipitate with sulphuric acid. This precipitate was collected, and 

 found to be strongly active, so that there is every reason to conclude 

 that the activity of the deposit is due to the presence of radium. 



The presence of radium in the Bath water and deposits is of special 

 interest because of the occurrence of helium in the gas which rises 

 with the spring.* There can be little doubt that the helium owes its 

 origin to the same store of radium that supplies the water. 



It is interesting to estimate the quantity of radium annually 

 delivered by the spring. Part of this is in the deposit. Part in the 

 water. But the annual yield of deposit does not exceed a few 

 hundred-weight at the most. And although it is much richer in 

 radium than the dissolved salt, the quantity of the latter is so 

 enormously greater, that the deposit may be neglected. According to 

 the estimate of Sir A. C. Eamsay, the late Director of the Geological 

 Survey, the salt annually delivered by the spring would be equivalent 

 in volume to a column 9 feet in diameter, and 140 feet high. Taking 

 the density to be twice that of water, this would weigh about 

 ■500,000 kilogrammes. 



* Rayleigh, ' Roy. Soc. Proc.,' vol. 60, p. 56. 



