PREFACE TO THE FIFTH EDITION. 



THE steadily increasing demand for this Manual has stimulated the 

 author to prepare this new edition with great care and with due con- 

 sideration of the needs of the student. The many changes and additions 

 made were necessitated not only by the general advance of science, but 

 also because of the desire of the author to bring this work in complete 

 harmony with the new Pharmacopoeia. 



The orthography recommended by the chemical section of the American 

 Association for the Advancement of Science has not been fully adopted, 

 for the reasons that neither the leading chemical journals nor the United 

 States Pharmacopeia use this spelling, and that it would be unwise to 

 have the student confronted with two different systems of orthography. 



As heretofore, the subject has been divided into seven parts each one 

 of which contains so much of the matter under consideration as is believed 

 to be necessary for a fair understanding of the subject. At the same time 

 care has been taken to place in the foreground all facts and data which 

 are of direct interest to the physician, pharmacist, and dentist, and to 

 exclude, as far as is compatible with the presentation of a comprehen- 

 sive view of chemistry, those portions which are of restricted interest only. 



In the first part the fundamental properties of matter are considered 

 briefly, and to such an extent as is necessary for an understanding of 

 chemical phenomena. 



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 atomic constitution of matter. Though the author 

 prefers to present these theories to his classes at the proper times during 

 the course of lectures, he does not deem it desirable to have them scat- 

 tered 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 

 la\v 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 to the instruc- 



J3373 



