INTRODUCTION. 



Early in 1872 I submitted to the Secretary of the Smithsonian Institu- 

 tion, the late Joseph Henry, a manuscript entitled "A Table of Specific 

 Gravities, Boiling Points, and Melting Points for Solids and Liquids." It 

 was accepted for publication, and in February, 1874, the printed copies 

 were ready for distribution. For years previously Professor Henry had had 

 in mrnd the publication of a series of similar tables somewhat upon the plan 

 long before suggested by Babbage, and accordingly my modest work was 

 given the somewhat ambitious title of "The Constants of Nature" and 

 made the first part of the proposed undertaking. Subsequently Parts II, 

 III, and V were furnished by myself and Part IV by Professor G. F. 

 Becker, and in 1876 I also published a supplement to Part I. 



The following tables form, in effect, a new edition of Part I, completely 

 revised, rearranged, and brought down as nearly as possible to the date of 

 printing. They are, however, modified by the omission of boiling and melt- 

 ing points, except when such data seemed essential to the proper identifica- 

 tion of a compound, on the ground that the magnificent tables of Professor 

 Carnelley already supply that want. I have limited myself to specific 

 gravity alone, following in the main the plan of arrangement adopted in 

 my earlier work, with such changes as were made necessary by the later 

 developements of chemical thought. Constitutional formulae have been 

 used, not according to any fixed rule, but according to convenience, and 

 their adoption has been governed, to some extent, by the limitations of the 

 octavo page. All other details have been subject to the same limitations, 

 and it is hoped that their absence will be compensated for by the almost 

 uniformly full references to literature. Some data could not be traced back 

 to their original sources, at least not without unwarrantable labor, and most 

 of these formed part of an early table prepared nearly twenty years ago for 

 my own private use. A few determinations are accredited to standard 

 works of reference, such as "Watts' Dictionary, Dana's Mineralogy, and the 

 like, and many have been drawn from the Jahresbericht. Absolute com- 

 pleteness cannot, of course, be claimed, and in some directions it has not 



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