PREFACE BY DR. HOFMANN, F. R. S.

I FEEL much pleasure in complying with the wish expressed by Messrs. Abel and Bloxam, that I should introduce the present volume with a few prefatory remarks.

The Authors, after having received their chemical education in my laboratory, officiated for some years as my assistants, and I have had ample opportunities of witnessing their talents for imparting information, and smoothing the path of the Student, in every department of analysis. The present volume is a synopsis of their experience in laboratory teaching; it gives the necessary instruction in chemical manipulation, a concise account of general chemistry, as far as it is involved in the operations of the laboratory, and lastly, qualitative and quantitative analysis. The plan adopted in the instructions for analysis is essentially that which was first introduced by Baron Liebig, and which, modified in accordance with the progress of science, and with the special requirements of the English student, I have daily practised myself, for the last eight years, in this laboratory.

I have no doubt that the work of Messrs. Abel and Bloxam will fulfil the purpose for which it was written, and will prove a useful laboratory guide to the chemical student.

ROYAL COLLEGE OF CHEMISTRY,

October, 1853.

A. W. H.

PREFACE.

It is with considerable diffidence that the authors venture to bring this handbook before the public, at a time when the rapid growth of the science of which it treats has called forth numerous works on all its branches, from the pens of chemists of the highest eminence, which leave nothing to be desired in clearness of explanation or minuteness of detail. Although, however, the different departments of chemistry, theoretical, practical, technical, and analytical, have been made the subjects of separate treatises, which may well rank as the classics of the science, there is as yet no single work which presents, even to those who can devote but a comparatively short period to the study of this necessary branch of an extended education, such a general view of practical chemistry, in its several relations, as shall enable them to acquire, with the least possible expenditure of time, a knowledge which will either suffice for the ordinary applications of chemistry to the useful arts, or will serve as a sound basis for the education of a professional chemist. To attain this very desirable end, it is obviously necessary to furnish the student, in many cases, with the result only of a long chain of reasoning, which he would otherwise have to elaborate for himself, without any advantage to compensate for the sacrifice of time.

It was not the intention of the authors, even if it had been in their power, to write a complete system of chemical philosophy, but rather to content themselves with entering only so far into theoretical considerations as is absolutely essential in practice, and to bring the laws which determine the results of chemical operations before the student, in such a form, that their mutual dependence might be clearly per ceived, and that they might readily fix themselves in the memory. In carrying out this design, however, some pains have been taken to avoid giving a concise description at the expense of a clear and satisfactory explanation.

The authors, having been engaged in laboratories where reference

has been made to them by chemical students respecting all the trivial difficulties met with in practice, have endeavored to turn their experience to advantage, in supplying information upon those points which, though apparently trifling, form great obstacles in the path of the beginner, and are not generally explained in treatises on scientific chemistry, since they are far too unimportant in themselves to occupy pages which are better filled with the philosophy of the science.

In the sections devoted to chemical manipulation, the various operations are described, as far as possible, in the order in which they would occur in the laboratory; thus, in considering the preparation of gases, attention is first directed to the construction of the apparatus, the bending of tubes, perforation of corks, &c.; next, the arrangements for collecting gases are noticed; and lastly, the transference of gases, and the various operations which may have to be performed upon them.

Chemical equations, which afford, at a glance, such clear explanations of various processes, have been freely used throughout that portion of the work which treats of elementary chemistry.

In describing the preparation of substances, details respecting the necessary apparatus have been omitted, since they have been given in the sections on manipulation. Since this book is not intended for a complete work of reference, or for an account of all the researches which have been made upon the subjects of which it treats, only those compounds are described, which appear to possess a certain practical importance. The descriptions of the processes involved in the different arts and manufactures have been stripped, to a great extent, of their mechanical details, in order that their chemical principles may be more readily mastered by the student. In the history of the che mical products obtained on a large scale, the methods employed by the practical chemist for ascertaining their value and for detecting the impurities to which they are liable, have, in most cases, been given.

There is appended to the technical history of the most important metals, a list of their chief minerals and ores, together with a brief outline of the methods usually followed in assaying the ores; these latter have been given more with the view of imparting to the student a general idea of such operations, than of enabling him to carry out, by the scanty directions there supplied, operations which fall strictly within the province of the metallurgist.

The reactions by which the rarer metals may be distinguished are introduced into their general history, to avoid unnecessary complication of the systematic course of analysis. When these metals are