DESCRIPTIVE INORGANIC GENERAL CHEMISTRY A Text-Book for Colleges BY PAUL C. FREER, M.D., PH.D. (Munich) PROFESSOR OF GENERAL CHEMISTRY, AND DIRECTOR OF THE LABORATORY OF REVISED EDITION ALLYN AND BACON Boston and Chicago HARVARD COLLEGE LIBRARY Chem 4.58.14 COPYRIGHT, 1894, BY ALLYN AND BACON. C. J. PETERS & SON, PREFACE. IN compiling the descriptive portions of this work, I have chiefly used GRAHAM-OTTO's "Lehrbuch der Allgemeinen Chemie" (last edition) and LADENBURG'S "Handwörterbuch der Chemie," although, wherever any of the facts which it was necessary to incorporate seemed doubtful, the original sources in the chemical periodicals have been consulted; of course, the discoveries which have been brought forth in the last few years are taken entirely from the latter. In the discussion of the double halides, of fluosilicic acid, and of similarly constituted bodies, I have adopted the views which have recently been brought into prominence by the publications of Prof. Ira Remsen, both in his larger text-book and in his contributions to current chemical literature. In those portions of the work which refer to the application of physical methods in the study of chemistry, OSTWALD'S "Outlines of General Chemistry" and LOTHAR MEYER'S "Theoretische Chemie " have been consulted and not infrequently quoted. My views upon the subject of valence and the use of structural formulæ may possibly be regarded by many of my colleagues as too conservative; but I have been led to adopt these views by the growing conviction that the dogmatic use of supposed laws of valence and of constitutional formulæ founded upon very incomplete experimental evidence, is causing more harm than good to the advancement of chemical science. In discussing chemical changes and reactions, I have endeavored to present the various topics, not as a series of isolated facts, but as so connected, the one with the other, that there is scarcely any one of the numerous phenomena which are mentioned in this work which does not find its analogon in some other portion of the field of chemical study. The attempt has been made especially to call attention to the influence exerted by the nature of the elements which make up a chemical compound upon the character of that compound itself. Tracing those connections may possibly have led me somewhat into the realm of speculation, notably so, perhaps, in my endeavor to explain the behavior of the hydrogen compounds of the not-metals by taking into consideration the relative influence exerted by the masses of the atoms which go to make the molecules. I hope, however, that the new arguments ventured on during the progress of this work will not be condemned without a hearing. Of course, a very complete knowledge of descriptive chemistry, both inorganic and organic, is necessary before the study of so-called physical chemistry can be pursued with profit; nevertheless, wherever it has seemed to me that some elementary facts from the realm of physical chemistry would be comprehended by the pupil taking up beginning chemistry, I have not hesitated to introduce the latter, at the same time giving references to the best of the smaller textbooks on the subject. The atomic weights which I have used are taken from the table recently prepared by F. W. Clarke, with the atomic weight of oxygen (taken as the standard) placed at 16. The laboratory notes in the appendix cover only the ground taken by the not-metals; they are not intended as a laboratory manual, but mainly as a guide to both teacher and pupil in compiling a list of experiments. Every teacher prefers using his own methods for laboratory instruction, with, of course, his own selection of the work to be pursued; in my own laboratory I follow a manual which is made up of brief directions, accompanied by a very complete set of questions, and all of the latter must be answered by the pupils. I do not think, however, that pupils should be left in the laboratory without other than a printed guide; far from it, I like to see the instructor always present in the room during laboratory hours, guiding and assisting his pupils, and not infrequently working with them. Probably this work cannot be advantageously employed in the secondary schools; indeed, it is adapted for the use of students who already have some knowledge of the elementary principles of the science. Beginners should be taken through a course in which only a few elements and compounds are discussed, with the purpose of familiarizing the pupils with the fundamental laws which govern chemical change. During the progress of such work as this, I would not advise the use of chemical symbols or any reference to the atomic theory. Our chemical symbols and equations are in existence, in their present state, only because of the difficult experimental work which has finally succeeded in establishing a consis PREFACE. tent table of atomic weights. It is manifestly impossible to make a student, without experimental knowledge, understand, in all its bearings, a theory which it has taken some ninety years to place upon its present footing. If an elementary course, in which every stated fact has been proved by actual experiment, precedes the work given in this book, the pupil will then be amply fitted to look at chemical phenomena from the basis of the atomic theory. It is in the hope that such a preparatory course has gone before, that I have begun this text-book with the atomic theory. ANN ARBOR, June, 1894. PAUL C. FREER. After the first five hundred copies were printed, the book was subjected to a careful reading by several chemists, so that, it is hoped, all misprints and errors have been entirely eliminated. PAUL C. FREER. ANN ARBOR, May, 1895. |