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morter and then thoroughly mixed with alcohol in a tall graduate or glass 

 cylinder. The rod supporting the brass disks is next carefully lowered into 

 the mixture of alcohol and uranium oxide. The uranium oxide settles to the 

 bottom, and in doing so deposits a layer upon each disk, the thickness and 

 amount of deposit depending upon the height of the shelf from the bottom. 



o 



6 



Q 



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After all the oxide has settled to the bottom the rod is removed and the disks 

 allowed to dry. By again weighing the disks the weight of the oxide upon 

 each one can be determined. Also by determining the density of the uranium 

 oxide the thickness of the films eau be calculated. These disks can nov, be 

 mounted upon metal plates for permanent use as ionisation standards, or 

 for student use in determining the fact that ionisation currents depend upon 

 the thickness of the layer of material up to a certain maximum thickness. 



