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100 Boltivood — Ratio of Radium to Uranium. 



quantity of the very finely powdered mineral was introduced 

 from a long, thin weighing-tube into the bulb B, and, except 

 where the reagent afterwards employed was concentrated sul- 

 phuric acid, enough water to cover the mineral was then intro- 

 duced into B from a small pipette. was then filled with 

 the acid used to decompose or dissolve the mineral and, the 

 capillary tubes at f and g having been already 

 closed, the tube CD was drawn out into a short 

 capillary and sealed off in the flame of a blast- 

 lamp. At the moment of sealing off, a slight 

 negative pressure was created in the interior of 

 the apparatus by drawing out a small portion of 

 the air through a rubber tube attached at D. 



The apparatus was tipped until the acid in C 

 ran over into B, and B was then warmed gently 

 until the mineral contained in it had been entirely 

 decomposed. The apparatus was then allowed to 

 stand undisturbed for several days to come into 

 equilibrium and the tube connecting A and B was 

 then drawn out into a short capillary and sealed 

 off at e. The bulb A, separated in this manner 

 from the rest of the apparatus, was then allowed 

 to stand for about two hours in order that any 

 rapidly decaying emanation (thorium or actinium) might be 

 entirely removed. The air and radium emanation contained in 

 A were then transferred to the electroscope in the following 

 manner : The capillary tube at e was first notched with a file and 

 then broken off under the surface of a strong sodium hydroxide 

 solution. Because of the diminished pressure in A, several cubic 

 centimeters of the sodium hydroxide solution would be drawn 

 into the bulb. A short rubber tube filled with water was then 

 slipped over e. The other end of this rubber tube dipped into 

 a vessel of water. A closed screw pinchcock was then attached 

 to the rubber tube near e and the bulb A was tilted so that its 

 interior walls were completely wetted with the sodium hydrox- 

 ide solution. This served to dry the gas somewhat and to 

 remove any acid fumes which might be present. The pressure 

 on the interior of the electroscope was now exhausted to about 

 one-half atmosphere and the stopcocks closed. The capillary 

 tubes atyand g were notched with a file and f was connected 

 with one of the stopcocks of the electroscope by a short section 

 of rubber tubing. The pinchcock at e was then opened, the 

 tip of the capillary tube f was broken off inside the rubber 

 tube, the stopcock of the electroscope was opened slightly 

 and the air in A was drawn over into the electroscope. When 

 the water had risen in A until it had reached the junction of 

 the side-tube g, the pinchcock at e was closed, the tip of g was 



