380 Boltwood — Radio-activity of JVattcral Waters. 



flask B. This flask lias a capacity of about four liters. 

 Through the stopper which closes it, there also passes a short 

 glass tube attached by a short rubber tube to the glass tube n. 

 The end of n dips into a good-sized beaker. The contents of 

 A and B can be brought to boiling by the heat from two large 

 gas-burners placed below the vessels. 



In making a separation of gas, the flask B is first filled about 

 one-half full of distilled water, which is boiled vigorously for 

 about fifteen minutes. In the mean time the vessel A is com- 

 pletely filled with the water to be tested, the cover a placed in 

 position and secured by the clamps, the rubber tube I) discon- 

 nected from the tin pipe, and the pinchcocks are all opened. 

 At the end of the 15 minute interval the pinchcock h is closed, 

 when the pressure of the steam in B will force the boiling 

 water from B into C and the tubing connected with it. When 

 these are completely filled with the hot water, the pinchcocks 

 D and i are closed and the cock k is opened. The tin pipe 

 attached to a is now filled full of distilled water and the rubber 

 tube D is slipped over it. The pinchcock D is then opened 

 and the gas lighted in the burner under A. 



The gas burette E, filled with distilled water, is connected 

 with i by a short piece of capillary tubing, and the screw- 

 pinchcock j is opened. As the temperature of the water in A 

 approaches the boiling-point, the gas is freely disengaged and, 

 passing through the tube c, accumulates in the upper part of 

 the gas receiver G By lowering the balance-receptacle i^and 

 opening the cock i the gas can be transferred from time to 

 time to the burette E. The water in A is boiled gently for 

 about 20 minutes. By a proper regulation of the pinchcock 

 at h and the burner under A the pressure within the apparatus 

 can be so regulated' that the height of the water column in G 

 is about 10 centimeters. The pinchcock at h is used in emer- 

 gencies when the water in A, having become slightly super- 

 heated, tends to boil too vigorously and the excess of steam 

 threatens to force the accumulated gas out of ^into B. In 

 such cases the cock h is closed, the gas under A turned off and 

 the cock i opened, permitting the excess of vapor to pass over 

 into E. 



Since natural waters almost always contain an excess of 

 carbon dioxide gas, a few cubic centimeters of a strong solu- 

 tion of sodium hydroxide is added on introducing the sample 

 into A. This combines with the free carbon dioxide and 

 reduces the volume of gas set free on boiling. 



After all the gas obtained from a given sample of water has 

 been transferred to the burette E, it is introduced into an air- 

 tight electroscope. This operation is carried out in the follow- 

 ing manner : 



