Radium Emanation at Low Temperatures. 



957 



receiver A, was forced slowly — usually about 0*4 c.c. 

 per sec. — over the path ABODE FG (see diagram). 



Carbon dioxide and water vapour were removed in the 

 tubes B and C containing calcium chloride and soda-lime 

 respectively. Condensation of the emanation from the 

 purified current of air took place in the spiral S cooled 



Fig. 1. 



rvotn Mavxofte 



Flask, 



nearly to liquid air temperature. The uncondensed emana- 

 tion passed to the open air outside the laboratory building 

 through the tubes F and Gr. After condensation of the 

 emanation a current of air (7' 5 c.c. per sec.) was blown for 

 several minutes from a Mariotte flask, through the calcium- 

 chloride tube X and the soda-lime tube Y, over the path 

 XYZEFGr. This air current carried outside the building 

 the emanation remaining about the tubes leading to the 

 electroscope. 



Next, a very sloiv and constant current of air from the 

 Mariotte flask was sent through the condensing spiral over 

 the path XYDEFG. This current was made very slow in 

 order for it to attain quickly the temperature at any point of 

 the spiral. 



