526 McCoy and Ashman — TJrano- Uranic Oxide. 



perfectly uniform film.* We have made a determination of 

 the saturation current in absolute units for the a radiation of 

 our standard of activity. To do this we made use of a stand- 



FlG. l. 



ard condenser of the concentric spheres type, in conjunction 

 with a gold-leaf electroscope. See fig. 1. 



The electroscope case consists of two rectangular compart- 

 ments, made of sheet brass l-5 mm thick. The ionization 

 chamber. A, is 19'5 cm square and 14 cm high ; the gold-leaf 

 chamber B is 8 by 10 cm and 12'7 cm high. The gold-leaf system 

 is insulated by an amber plug, D, and carries as its lower end 

 the circular electrode, E, a brass plate 14 cm in diameter. F is 

 * McCoy, J. Arner. Chem. Soc, xxvii, 395, 1905. 



