384 Boltivood — Radio-activity of Natural Waters. 



acetic acid being added to prevent the precipitation of carbon- 

 ates. After boiling, the water is allowed to stand for several 

 hours in contact with the air and is then introduced into a 

 bottle and tightly sealed. The capacity of the bottle should 

 be such that the water completely fills it, leaving only the 

 smallest possible air space below the stopper. The water is 

 then allowed to stand for a sufficient length of time (say 16 

 days) and is then boiled again in the apparatus shown in fig. 

 1. If radium salts are present in the water, the gases given off 

 on this second boiling will contain the accumulated radium 

 emanation, and the relative quantity of radium present can be 

 calculated from the observed activity of the gas. 



Radio-active Waters. 



A considerable number of samples of radio-active waters have 

 been examined by the method herein described. Data on only 

 three of these is at present available. The sources of these 

 three samples were the following : 



No. 1. "Water from a spring at Windham, Me. This spring 

 is known as the " Maine Granite Spring," and is stated to issue 

 from a granite and sandstone formation, to have an estimated 

 flow of 100 gallons per minute and to have a temperature of 

 43° Fahr. throughout the year. This sample was tested four 

 days from the time of collection and was obtained through the 

 courtesy of Prof. Chas. F. Mabery. 



No. 2. Water from a spring in one of the public parks of 

 the city of New Haven, known as " Cold Spring." The for- 

 mation immediately adjacent to the spring is red sandstone, and 

 the temperature of this spring on September 5, 1904, was 52° 

 Fahr. The flow is small. 



No. 3. Water of the city supply in New Haven, drawn 

 from the pipes in the laboratory. 



The radio-activity of the gases from these samples is given 

 in the table which follows : 



Table. 



Sample 



Liters 



Leak 



Leak 





No. 



taken. 



measured. 



per liter. I. 



Io. 



1 



8-9 



9*91 



1*11 63-22 



128-6 calculated. 



2 



8-9 



0-61 



0-068 



3-9 measured. 



3 



8*9 



0-0036 



0-0004 



0-025 " 



The leak is expressed in divisions per minute, the values of 

 I and I are expressed in terms of grams uranium XlO" 4 per 

 liter of water. The value given for No. 3 is the mean of 

 three separate determinations. The value of the constant, a, 

 employed in the calculation was that determined by Eumstead 

 and Wheeler. 



