iv PREFACE TO THE TENTH EDITION. 



In the first part, treating of chemical physics, the student finds a brief 

 discussion of those physical conditions of matter which have a close rela- 

 tionship to chemical phenomena, and also of the principles which lead to 

 an understanding of many of the instruments, such as the spectroscope, 

 polariscope, etc., which he uses in his chemical operations. 



The second part treats of those principles of chemistry which are the 

 foundation of the science, and enters briefly into a discussion of theoretical 

 views regarding the constitution of matter. Though the authors prefer 

 to present these theories to their classes at the proper times during the 

 course of lectures, they do not deem it desirable to have them scattered 

 throughout the work, believing it better to assemble them compactly in 

 print, so that the student may be able to study them after having acquired 

 some knowledge of chemical phenomena. 



The third and fourth parts are devoted to the consideration of the non- 

 metallic and metallic elements and their compounds. While the periodic 

 law furnishes a most admirable basis for a scientific classification of ele- 

 ments, yet their consideration according to a strict adherence to periodicity 

 does not seem advisable in this book. For this reason the old classifica- 

 tion of metals and non-metals, organic and inorganic compounds has been 

 retained, since experience has shown it to be well adapted for the instruc- 

 tion of beginners in chemistry. 



The fifth part is devoted to analytical chemistry and will serve the 

 student as a guide in his laboratory work. Qualitative methods are 

 chiefly considered, but a chapter is added giving official methods for 

 volumetric determinations. 



The sixth part treats of organic chemistry. Though it is impossible to 

 include within the limits of this text-book an extended consideration of a 

 branch of chemical science so highly developed, yet it is believed that an 

 intelligent study of this part will familiarize the student with carbon 

 compounds sufficiently to give him a clear understanding of their general 

 character, and a knowledge of the bodies which are most important in 

 medical science. 



The seventh and last part gives the principal facts of physiological 

 chemistry. Special care has been taken also to introduce here the most 

 modern methods for chemical examination in clinical diagnosis. 



The authors will be grateful for any suggestions looking to the im- 

 provement of the book. 



The authors wish to express here their obligations to G. Howard 

 White, Jr., M. D., by whom the section on physiological chemistry was 

 rewritten. 



W. S. 



D. B. 



BALTIMORE, 1912. 



