16 THORIUM IN AN ELECTRIC FIELD. — HENDERSON. 



rest atoms were initially partly charged and partly uncharged. 

 In this respect thorium seems to differ from radium. It was 

 shown by Wellisch that, in hydrogen and in carbon dioxide, 

 the rest atoms of the latter are partly charged and partly 

 uncharged. The case of air is peculiar as it is a mixture. 

 Further investigation along these lines is in progress. 



Summary. 



A new type of vessel for this kind of work has been de- 

 veloped and its advantages noted. 



It has been shown that in dry air all the thorium rest 

 atoms are initially positively charged. 



In pure ether vapor all the thorium rest atoms are initially 

 uncharged and in a mixture of ether vapor and air the charged 

 condition of the rest atoms depends on the relative amounts 

 of ether vapor and air present. A similar state of affairs 

 appears to be true with water vapor. 



In conclusion I wish to express my best thanks to Dr. 

 Bronson, who suggested the work and without whose con- 

 tinued interest this work would not have been possible. 



