Professor Brande's Lectures on the application of Organic Chemistry to the Industrial Arts, are in course of reproduction from his Lecturing Notes, and, with his sanction, they will shortly appear.

PREFACE.

HAD this volume consisted of Professor Faraday's Lectures alone, it might have gone into the literary world without further preface than such as is conveyed in the intimation of its appearance with the fullest sanction and consent of the lecturer. An explanation, however, is rendered necessary, when, as in the present case, an editor intersperses additions of his own.

It may suffice on this topic to state that the extraneous portions of the volume suggested themselves during an interview with Professor Faraday, in the course of which the process of rendering an oral discourse into a literary shape formed the topic of conversation. It was conceded that lectures, for the most part, have reference to others already delivered; that a lecturer frequently indicated

collateral facts merely; not demonstrating the line of evidence by which these facts had been arrived at-because so far as might relate to a particular audience the knowledge of such facts was assumed. It was conceded, moreover, that a chemical lecturer, more perhaps than any other, possessed a means of demonstrating facts not available to the essayist the demonstration of experiment that mute eloquence of action which silently compresses whole pages of written lore into one short act of manipulation, and renders verbal explanation unnecessary.

These and many other special peculiarities, in which the functions of a lecturer differed from those of an author, having been discussed-it was conceded that a mere verbatim report of an experimental course of lectures, would by no means render, under a literary aspect, the spirit in which these lectures were delivered.

Accordingly-being anxious to obtain these lectures for a public journal, it appeared that the object would be most efficiently secured by attending them regularly-embracing their scope, noting their experiments, striving to imbibe their philosophy—and transferring their language to paper,

whenever language, not experiment, might be the form adopted for expressing a sentiment, or inculcating a truth.

This plan was adopted accordingly and to render it still more perfect, Professor Faraday kindly and cordially furnished, immediately on the conclusion of each discourse, his lecturing notes: moreover, whenever any difficulty occurred, he no less kindly lent the aid of his supervision. Originally intended for the pages of a journal, the rendering of Professor Faraday's lectures was necessarily much condensed; when therefore public appreciation had made a fuller expansion of them desirable, the lecturing notes of Professor Faraday proved of redoubled utility; containing, as they did, various memoranda of points indicated for discussion, but not touched upon during the lecture for want of the necessary time. These dormant notes I have frequently taken the liberty to expand.

Enough will have been stated to make known the warrantry under which I have acted in rendering the lectures themselves; and it equally applies as accounting for the existence of those parts of the volume which are my own: parts

which are merely to be considered as very unworthily taking the place of other sources of information with which Professor Faraday assumed his audience to be acquainted, and to portions of which he referred.

In conclusion, I have now to add, that although the contents of the following pages will be recognised by those who had the gratification of listening to the original lectures, as in spirit always, in language frequently-similar to their oral prototypes: yet, in deference to the wishes of the lecturer, it remains for me to state that the present volume is to be considered the result of an appreciation by others rather than himself of the merits of the lectures embodied in this course.