R. R. Ramsey — Radioactivity of Spring Water. 309 



Art. XXIV. — Radioactivity of Spring Water ; by R. R. 



Ramsey. 



The springs tested are flowing springs which issue from the 

 ground at the base of or on the side of a hill. A great number 

 are those which were used by the early settlers as a source of 

 water supply. Some are still the main water supply of the 

 farm. Most of these springs are the so-called " never-failing " 

 springs which flow the entire year. All are more or less 

 affected by the rainfall. 



The wells are dug, driven, or drilled wells whose depth varies 

 from 15 feet to 150 feet. Pumps must be used to raise the 

 water to the surface of the ground. 



The method of measurement is the "shaking method" as 

 used by Schmidt* in which a known volume of water is shaken 

 vigorously with a known volume of air for two minutes, and 

 then the air is pumped through the chamber of the electroscope 

 by means of a rubber bulb pump until the emanation is 

 thoroughly mixed with the air in the electroscope and the air 

 in the shaking can. Then the following equation holds: 



*^m( 



v, tMI.l 



Where, V, = the volume of water in the shaking can. 



"y __ a a a «j r " " " " 



V 3 = " " " " " " bulb pump and connect- 

 ing tubes. 

 V 4 = " " " " " " ionization chamber, 

 a = the absorption coefficient of water for radium 



emanation. 

 e = the amount of emanation per liter in V 4 , the elec- 

 troscope. 

 E = the amount of emanation per unit of volume of water. 



Electroscope. — The electroscope used at first was one made 

 in the shop of sheet tin. Sulphur was used as an insulator. 

 Later a Schmidt electroscope made by Spindler and Hoyer, 

 Gottingen, was used. Both electroscopes were calibrated by 

 using Duane and Laborde's formula,f 



_ W 



~ 6-31 X 10 6 (1 - 0-572 S/ V) CUneS 



*Phys. Zeitschr, vol. vi, p. 561, 1905. 



fLe Radium, vol. xi, p. 5, 1914; Ann. der Phys., vol. xxxviii, p. 959, 

 1912 ; Compt. Rendus, vol. el, p. 1421, 1910 ; Jour, de Phys., vol. iv, p. 605, 



