PREFACE. 



Tliis Index to the Littiatuie of 'J honuni lias Ijeen jirepared after a 

 veiy laborious and ])ainstaking search throuirh many scientific and 

 technical journals. 



Most of the references have been verified, and usually the orijiinal 

 article heads the list, but in some few cases this was difficult to 

 determine. 



It is not offered as absolutely com})lete, and the compiler requests 

 that any one using the index would send corrections and addenda to 

 him. 



Minerals now recognized as containing thoriinn have been mentioned 

 only in such cases when the earth has been found. The patent litera. 

 ture relative to the use of thorium in the arts is not included. 



C. H. J. 

 Columbia Ukiversity, 



New York, 1902. 



