building. These are intended to receive the iron pipes of such moveable furnaces as may be occasionally employed.

F. Is a furnace containing an iron sand-pot calculated ́for distillation with a glass or earthen retort, as represented at F. in the section. This furnace is so constructed that the iron pan may be readily removed, and a copper still, an iron retort, or other apparatus,, placed in its stead.

GG. A muffle-furnace for assaying metals by cupellation, for experiments on enamelling and staining glass, and for the roasting of metallic ores, &c.

HH. A furnace for distillation by the naked fire. In the section H. is placed a retort, the neck of which passes through an opening left in the side of the furnace for that purpose, and which is luted up during an operation. This furnace is well contrived for the distillation of phosphorus, quicksilver, oxygen gas, &c.

II. Iron doors opening on a level with the furnace grates,, for the purpose of raking the fire, removing and replacing the bars, &c.

K K. Doors of the ash pits.

L. A smelting- or wind-furnace for the reduction of metallic ores, and other purposes requiring the highest degrees of heat. Section L. shows the interior of this furnace, with a crucible within it: M. is an aperture for clearing or withdrawing the bars of the grate.

N. A reverberatory, or annealing, furnace. This forms a chamber through which the heated air and flame of the furnace L. pass in their way to the chimney O. This addition is found to improve materially the draught of the furnace L, and is also particularly useful in heating crucibles to a proper temperature preparatory to their being used in that furnace.

PP. Moveable covers suitable for either of the furnaces G, H, L, or N. These covers are made with fire-bricks ground neatly, and bound together by a strong rim or band of iron. There is a hole in the centre of each, secured by an earthen

stopper, which may be opened occasionally to inspect the state of the fire or the progress of the operation.

Q. An extended ash pit, covered by a moveable iron grate. This kind of ash pit very much, œconomizes the room in a laboratory, as it admits a large current of atmospheric air, and allows the operator to stand closer to the furnace. Throughout the whole of this apparatus, the chimneys are distinct, each furnace having its own; but being carried up within the wall of the building they cannot be described in this plan.

R. fig. 3, represents Mr. Knight's table-furnace made of wrought iron, of dimensions according to the scale annexed, the inside of which is lined with a coating of fire clay. S. a door to allow the introduction of a crucible, &c. T. another door in the cover, through which the fuel (charcoal) is to be introduced. U. an opening which serves as a chimney when the top is taken off and a sand pot is to be used; or it will admit the neck of a retort for the purpose of distilling with the naked fire; this opening is also calculated for the introduction of a muffle. X. the door of the ash pit. W W. two apertures, opposite to each other, through which an iron, earthen, or any other tube may be passed, in order to demonstrate the decomposition of water, and for other operations which require such an arrangement.

AN ESSAY

ON

THE UTILITY OF CHEMISTRY

ΤΟ

The Arts and Manufactures.

Addressed to Parents in the higher and middle Ranks of Life.

FROM the present state of chemical knowledge, and the

rapid improvements in our arts and manufactures by the judicious application of its principles, it is become desirable that every youth should be acquainted with its rudiments, and that CHEMISTRY should be made a regular branch of education.

I have therefore imagined that I should render an acceptable service to society by showing the advantages which arise from the acquisition of this kind of knowledge; for, as a large proportion of the community is not apprized of its real value, that general attention to it which it deserves, can never be expected until its utility be demonstrated.

It would, however, be no difficult matter to show that the world might derive great advantages even from the dif fusion of a theoretical knowledge of philosophy and chemistry. An instance or two will place this assertion in a clear point of view. Two thousand years ago Archimedes was ridiculed for his attention to mathematics and the abstruse sciences: yet by this knowledge he was enabled to

invent such mechanical engines as were sufficient to resist the whole Roman army. And such a dread had the soldiers of this man's science, that if a rope only were let down from the walls of the city of Syracuse, the whole army would retire from before it in the utmost consternation.

A further proof of the importance of the dissemination of useful knowledge may be taken from the construction of the Steam Engine. Mr. Watt often acknowledged that his first ideas on this subject were acquired by his attendance on Dr. Black's Chemical Lectures, and from the consideration of his theory of latent heat and the expansibility of steam.

The well-informed people of France are so satisfied of the importance of chemical knowledge, that chemistry is already become an essential part of education in their public schools. It shall be my business in this place to endeavour to demonstrate it to be of equal importance to the various classes of our countrymen, that the science should be cultivated with the same ardour in these kingdoms. The science we here recommend to your regard, has for its objects every substance of the material world, and, therefore, is equally interesting to every civilized nation upon earth.

Is your son born to opulence,-is he the heir to an extensive domain; make him an analytical chemist, and you enable him to appreciate the real value of his estate, and to turn every acre of it to the best account.

Chemistry will teach him also how to improve the cultivated parts of his estate; and by transporting and transposing the different soils, how each may be rendered more productive. The analysis of the soils will be followed by that of the waters which rise upon or flow through them ; by which means he will discover those proper for irrigation; a practice the value of which is sufficiently known to every good agriculturist.

Should he occupy his own estate, and become the culti