378 Bolhvood — Radio-activity of Natural Waters. 



Art. XL. — On the Radio-activity of Natural Waters ; by 

 Bertram B. Boltwood. 



The occurrence, in the water of the public supply of Cam- 

 bridge and the water from a number of other English localities, 

 of a radio-active gas having properties similar to those of the 

 radium emanation, has been demonstrated by J. J. Thomson* 

 and confirmed by E. P. Adams.f Bumstead and Wheeler;); 

 have also shown that a similar radio-active gas is contained in 

 the city water supply of New Haven, Conn., and in water 

 from a spring at New Milford, Conn. That the waters from 

 the hot springs at Bath and Buxton in England also contain 

 radio-active gases has been demonstrated by Allen and Blyths- 

 wood,§ who examined the gases given off at the springs and 

 also the gases which escape from the water on boiling. The 

 presence of minute quantities of radium salts in these waters 

 and also in the sedimentary deposits formed at the point of 

 issue, which has been observed by Strutt,|| is of considerable 

 importance since it has been shown by Rayleigh^f that the 

 gases which rise with the springs consist in part of helium. 



Mention is made by Himstedt** of the occurrence of radium 

 emanation in the waters of the thermal springs at Baden- 

 Baden, Germany, and an examination by Elster and Geitel+f 

 of the sedimentary deposits formed at these springs, has made 

 it evident that these deposits contain radium compounds. 



Curie and Laborde^f have recently tested the gases given 

 off at certain mineral springs of European origin and by the 

 waters of these springs on boiling. They examined gases from 

 nineteen different sources, fourteen of which they found to be 

 radio-active. The radio-active properties of the gases corre- 

 sponded to those of the radium emanation. §§ 



Radium emanation has also been found to occur in crude 

 petroleum and natural gas, as well as in the air drawn from 

 the ground in a number of different localities. 



The object of this paper is to describe a method for the 

 quantitative determination of the radio-active gas contained in 

 a water and to furnish a convenient standard. for measurement 

 and comparison ; also to offer some experimental evidence as 

 to the origin of the radio-active properties of natural waters. 



* Nature, lxvii, 609 (1903) ; Proc. Gambr. Phil. Soc, xii, 172 (1903). 



f Phil. Mag., viii, 563 (1903). 



{This Journal, xvi, 328 (1903) ; ibid., xvii, 97 (1904). 



§ Nature, Iviii, 343 (1903) ; ibid., lxix, 247 (1904). 



|| Proc. Eoyal Soc. London, lxxiii, 191 (1904). 



1[ Proc. Royal Soc. London, lx, 56. ** Ann. d. Physik, xiii, 573 (1904). 



•ft Physikal. Ztschr., v, 321 (1904). 



iiCompt. Rend., cxxxviii, 1150 (1904). 



§§ H. Mache, Physik. Ztschr., v, 441 (1904). 



