First year chemistry : a text in elementary chemistry for secondary schools

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COPYRIGHT DEPOSIT.

A TEXT IN ELEMENTARY CHEMISTRY FOR SECONDARY SCHOOLS

BY

WILHELM SEGERBLOM, A.B.

INSTRUCTOR IN CHEMISTRY AT THE PHILLIPS EXETER ACADEMY

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PROCFiESSVS REVELAT.IOKE

EXETER, N. H.

EXETER BOOK PUBLISHING COMPANY

Copyright, 1909 By Wilhelm Segerblom

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The News-Letter Press Exeter, N. H.

Preface

This book is not a synopsis of the whole of chemistry; nor is it a collection of sample fragments from the various departments of this rapidly widening subject. It embraces as much of the essential facts and influences of chemistry as the ordinary student can assimilate in one year's study of the subject, presented in the order that the human mind — particularly the student mind — exploring new regions naturally works, and tied into a logical and connected whole.

Briefly, my plan is: To use the inductive method rigorously in the first ninety experiments — about one-third of the book — beginning with the metals instead of with the nonmetals, in the belief that the student can get more tangible results from the more tangible substances. The last four of these ninety experiments contain a short chemical investigation of a substance whose composition is unknown to the student at this stage of the year's work. The performing of these ninety experiments reveals to the student the methods of thought used by the chemical investigator in attacking his problems, — the same method that he (the student) must use on a small scale in solving his own difficulties; the result of all this is that the student is taught to think his own way out of all his difficulties. Here I drop the strictly inductive method, for I realize that it caniv PREFACE

not be used to advantage in teaching theory and the large amount of descriptive matter that comes later. The investigation is followed by the theory of chemistry, with experiments to illustrate the laws and principles; this comes at the middle of the } r ear, — a period now approved by many teachers. The theory of chemistry is followed by considerable descriptive chemistry, studied in the light of present theoretical conceptions, but with the spirit of the inductive method still an unconscious guide.

The author realizes that he has struck out into unbeaten paths and may, perhaps, be going in cross directions to the trend of many chemistry teachers, but he feels confident of the correctness of his mental compass, for he has watched carefully the trial trips of the text in his own classes during the past four years; and, after all, the worth and value of a text lies in its ability to lead the confident and confiding student mind naturally and progressively up towards the hights of vision already attained by the teacher.

My object has been to give the student a conception of chemistry from the point of view of the scholar and the thinker, rather than from the point of view of the crammer, i.e., to teach chemistry rather than to teach a text-book. It is generally accepted that the chemistry of the laboratory is the only real chemistry, and that the atom and the ion are simply helps in discussing facts; and for this presentation of the subject the deductive method is as essential as the inductive.

As lie Bon says: "No physical law is now capable of exact verification. All are merely approximations to the truth, stating what would be the case if all disturbing factors were removed." Be that as it may, every thoughtful teacher of laboratory science knows how difficult it is to eliminate these " disturbing factors" from the experiments that are to be presented to the student, and then after the

PREFACE V

elimination to have anything left worth presenting that can be worked into a united whole. The author will doubtless be pardoned for saying that he first laid out the logical plan of experimental chemistry presented in these pages, but that by far the bulk of his work has been to adapt the work to the ability and limitations of the beginner by eliminating and circumventing as many as possible of those ''disturbing factors" that lead to secondary and confusing phenomena.

The paragraphs in fine print at the end of many experiments answer briefly just those questions which arise in the alert student mind but which cannot easily be answered from the student's personal observation in the laboratory. Each teacher must of course use his own judgment in the use of the fine print notes, elaborating them, if he thinks it necessary, to the extent that each class is ready for and seeks such elaboration. The author finds it advisable not to go into great detail in such elaboration, — at least not in the first ninety experiments.

William A. Noyes, when speaking of the contribution of chemistry to modern life in his recent inaugural address at the University of Illinois, said: " While the material advantages which have come to us from chemistry are very great and may be justly emphasized, its greatest achievement is, after all, the part which it has had, together with other sciences, in transforming the way in which the world thinks. In its laboratory method it has replaced the old idea of authority by the idea of first-hand knowledge. It leads the individual to seek for himself the fundamental basis of his knowledge and it leads him not merely to pass knowledge on to the next generation, but to transform it into a new and truer form. And as this scientific spirit permeates society, it more and more destroys deceit and fraud, wherever found." If the author vi PREFACE

has succeeded in furthering this spirit of improved thinking, then his labors in preparing this little text have not been in vain.

Thanks are gratefully accorded those of my pupils and other friends who by criticism or suggestion have aided in perfecting these pages. Mr. W. A. Stone, of Albany, N. Y., has read the manuscript; Mr. J. B. Merrill, of Woonsocket, R. I., has read both manuscript and proof; their kindly interest and helpful suggestions are gladly acknowledged. To my former teacher, Dr. George R. White, of Wellesley Hills, Mass., I am most deeply indebted; during my student days his sympathetic teaching opened up to me the alluring field of chemistry, and without that introduction the development of this little text and the scientific hopefulness which has made its preparation more a pleasure than a burden would not have been possible. The author assumes the responsibility for the statements in this book. Any corrections or comments on the text will be gratefully received.

W. S.