This little book has been prepared as a popular introduction to the study of chemistry.

It is probably needless to recommend the _subject_: chemistry is recognized as a science of such general interest, such wide usefulness, and such universal application, that no intelligent person can endure long to remain ignorant of its principal facts and laws.

This book treats principally of the _non-metals_; it is believed to be the verdict of authors and teachers of experience, that these furnish the most suitable material for a beginner in the study of chemistry; these best present the fundamental facts and principles of the science, and they do it in connection with objects and phenomena easily accessible to almost every civilized human being.

The author contemplates the preparation hereafter of a book of similar general character, only having its principal facts drawn from the chemistry of the _metals_.

In writing this book it has been the effort to treat the subject in a style that shall be attractive to the general reader; but it is believed that in no case has scientific fact been sacrificed in the interest of popular form.

The arrangement of matter in the book is in accordance with the following plan: After the introductory chapters, which present the general principles of chemical action, the chief non-metals are treated in a scientific order as follows: the _monads_, hydrogen, chlorine, bromine, iodine, and fluorine; then the _dyads_, oxygen and sulphur; next the _triads_, boron, nitrogen; finally the _tetrads_, carbon and silicon; thus including the four great groups into which the non-metals are naturally arranged.

The _historical and biographical sketches_, that are distributed through the book, have been introduced with the view of legitimately helping to retain the reader’s attention. Most of the _experiments_ described are such as may be performed by any one possessed of reasonable skill; it is believed that they will afford profitable instruction as well as entertainment. Allusions to the _applications of chemistry_ to the affairs of every-day life have been carefully introduced and have been developed as fully as the circumstances seem to warrant.

Perhaps some comment upon the _reading references_ (pp. 10, 17, 24, 27, 31, 38, 45, 56, 73, 84, 98, 111, 116, 133, 156, 161, 186, 196, 214) is proper. They are largely from periodical publications, and it is thought that they will be of service, especially to mature students. Helps to reading are now viewed as among the most important offerings of teachers to learners. The reading lists in this book point out some papers which are selected as being chiefly popular in style; if these lead the reader to consult the others he will find himself introduced to some of the most important contributions to the knowledge of our science.

BROWN UNIVERSITY, August, 1884.