LETTER OF TRANSMITTAL. 



New York, July 24, 1894. 

 The Committee of the American Association for the Advancement of 

 Science having charge of Indexing Chemical Literature has voted to recom- 

 mend to the Smithsonian Institution for publication the three following 

 Indexes : — 



An Index to the Literature of Cerium.^ 

 An Index to the Literature of Lanthanum.^ 

 Both by W. H. Magee, Ph. D. 



An Index to the Literature of Didymium. 

 By A. C. Langmuir, Ph. D. 

 The latter has already appeared in the School of Mines Quarterly, No. i, 

 Vol. XV. 



H. CARRINGTON BOLTON, 



Chairman. 



To the Secretary of the Smithsonian Institution. 



* These Indexes are printed as Smithsonian Publication No. 971. 



