PREFACE. 



The following supplement to Part I of the Constants of Nature, eon- 

 tains, in addition to determinations published during the past two years, 

 some materials which were overlooked in compiling the original work. In 

 it data are given for nearly seven hundred substances, of which at least four 

 hundred are new since the publication of Part I. 



Of course the compiler is anxious that his work should be as thorough 

 as possible, and hence he will be greatly obliged to any person calling his 

 attention to errors or omissions. He would also request investigators having 

 unpublished determinations on hand to favor him with copies of them for 

 use in subsequent supplements or editions. Such material is always wortti 

 saving, even when it is not of sufficient value to warrant publishing ln T itself. 



Few explanations are needed in this supplement. The arrangement 

 and abbreviations are the same which were originally used, with the excep- 

 tion of a very few new titles for periodicals. These are abbreviated as 

 follows : — 



B. D. C. G. "Berichte der Deutschen Chemischen Gesellschaft." 



B. II. A. S. F. "Bulletin Hebdomadaire de l'Association Scientillque de 



France." 



C. C. or C. Cent. "Chemisches Centralblatt." All references to this 



periodical apply only to the third or current series. 

 Fortsch. d. Phys. " Fortschritte der Physik." 



F. W. C. 



Cincinnati, March 9, 1876. 



