PREFACE TO THE SECOND EDITION. 



THE rapid progress made by Chemistry within the last decade, and the 

 changes in the methods of instruction, hare necessitated a new edition of 

 this standard work. The alterations deemed advisable have been chiefly 

 of four kinds omission of sections, insertion of new ones, introduction 

 of the latest nomenclature and chemical formulae throughout, and a com- 

 plete rearrangement of the matter. A rearrangement of the chapters re- 

 lating to Organic Chemistry on a strictly scientific basis was found imprac- 

 ticable, consequently the empirical plan adopted by the author has been re- 

 tained, while the editor has endeavored to point out the desirable method 

 of classification of organic bodies in Chapter XXTV. 



The sections relating to Chemical Philosophy, especially in Chapters II. t 

 III., and IV., have been entirely rewritten ; the chapter on Galvanism in 

 the first edition has been omitted, the subject being now treated in connec- 

 tion with Physiqs ; a brief chapter on Spectrum Analysis has been added ; 

 and, lastly, the Metric System of Weights and Measures and the Centigrade 

 Thermometer have been adopted as standards throughout the work. Tables 

 explaining these standards are given in an Appendix. 



Many wood-cuts have been added, and nearly all are new. The intro- 

 duction of two sizes of type may aid the teacher in the instruction of young- 

 er scholars. The questions in this edition are placed at the end of each 

 chapter, instead of being collected at the end of the book. 



Finally, the editor expresses the hope that he has not entirely obliterated 

 the pleasant, familiar manner of treating the subject so happily adopted by 

 the author and so successfully carried out. 



H. CAKBINGTON BOLTON, Ph.D. 



SCHOOL OF MINES, COLUMBIA COLLEGK, ) 

 September, 1ST5. 



