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.

CHEMISTRY OF THE NON-METALLIC

ELEMENTS.

GENERAL INTRODUCTION.

I.

THE QUALITY AND TENDENCIES OF CHEMICAL PHILOSOPHY -FIRST CHEMICAL EPOCH-ALCHEMY-BELIEF

IN

OCCULT AGENCIES-PARACELSUS-THE INFLUENCE OF
HIS CHARACTER AND WRITINGS.

WHILST it is the peculiar attribute of astronomy to
awaken our minds to an appreciation of those stupen-
dous orbs which revolve in space, to waft us ideally into
those far-off regions where the bright luminary of our
system would pale into the feeble twinkling of some
distant star, and this turbulent world of ours, if not lost
altogether to our gaze, would fade into the misty streak
of some faint galaxy-it is an attribute of chemistry to
raise within us sentiments of another kind.
Less stupendous in its first aspect than astronomy
though it be, the science which teaches us to contem-
plate the immensity of space, and the grandeur of
its orbs; less tangible than astronomy in its first
manifestations-chemistry, nevertheless, by the wonder-

up

B

ful metamorphoses which it discloses, by the protean display of physical changes which it brings before our eyes, by the demonstration it affords of the indestructibility of matter under the agency of existing laws, is perhaps more calculated than any other science to awaken within us the most ennobling sentiment the mind can contemplate-the sentiment of immortality. If the grosser parts of our earth and its inhabitants pass thus undestroyed through all the vicissitudes of death, fire, and decay, how impossible is it to assume a destruction of a spiritual essence! Totally irreconcilable with the genius of chemical science is the idea of destruction.

Chemistry is essentially a science of experiment ;most of the conditions under which its phenomena are developed requiring the disposing agency of man: yet there occur naturally a sufficient number of chemical phenomena to rivet the attention of a reflective mind, and lead it to some acquaintance with that mutation of form apart from destruction which is so striking an attribute of chemistry.

Many a reflective sage must have speculated ere now during the very infancy of the world, and long before chemistry had invoked the aid of experiment, on the cause and consequence of such ever-recurring phenomena as combustion and evaporation. The circumstance must have been noticed that the waters of lakes and streams, although exhausted in vapour by the agency of the sun's rays, and dispersed, were not dis