Bolticood — Radio-activity of Natural Waters. 



379 



Method of Determination. 

 The gases dissolved in a water can be conveniently separated 

 and collected by the method described by Keichhardt.* The 

 apparatus as ordinarily constructed is too small for the purpose 

 under consideration and requires certain modifications. It con- 

 sists (fig. 1) of a vessel A made from sheet copper and having 



a capacity of about 9 liters, 

 diameter, is surrounded by a 



The orifice of this vessel, 9 C 



m 



heavy brass 



ring, 



15 cm in outside 



diameter, to which can be attached by clamps a heavy brass 



plate a, having a block-tin pipe soldered into an opening in its 

 center. A rubber gasket, 3 mm thick, between the plate and 

 the ring makes the joint perfectly tight when the clamps (6 in 

 number) are screwed up tightly. A piece of thick-walled 

 rubber tubing carrying a screw-pin chcock D connects the tin 

 pipe with the glass tube c, which extends to the gas receiver 0. 

 This latter is 52 cm in length and 3 cm in diameter and has a total 

 capacity of about 350 cc . The tube c protrudes about 20 cm into 

 C beyond the rubber stopper at the bottom. The top of C is 

 drawn out into a short, narrow tube and is closed by a rubber 

 tube and a screw-pinchcock, i. The tube g passes from the 

 bottom of C and is joined at h, by a piece of rubber tubing 

 carrying a screw-pinchcock, to a glass tube which passes 

 through a rubber stopper and extends to the bottom of the 



*Hempei's " Gas Analysis" (translated by L. M. Dennis). 



