application to discriminating duties, of a principle which referred only to revenue duties, has been so thoroughly laid bare by the writer in the Edinburgh Review, that we feel no desire to pursue that branch of the subject farther. We think, however, that Sir Robert Peel has himself furnished us with a position. Undoubtedly it cannot be laid down as a general rule, that the reduction of taxation will not interfere with revenue. We never heard it so laid down. That two plus two do not always make four, is the utmost of Sir Henry Parnell's proposition, that two minus two do make four, (which is, in fact, what Sir Robert Peel would state for him,) we will take leave to say, never entered into his mind. The question is, how far, by reducing taxation, you will increase consumption, and, by that means, revenue. If the habits of the people do not lead to increased consumption of an article placed within their reach, a reduced duty will, of course, be followed by reduced revenue. The reduction of the coffee duty owed its success to the growth of more temperate habits among the people. We believe a similar result may follow the present reduction in spite of the increased colonial protection thereby effected. Our hopes will be stronger, if we should find that the foreign growers will still be able, as heretofore, to "colonize" their coffee at the Cape, and so change the discriminating duty of 100 into one of only 25 per cent.

It must be remembered, however, in estimating the effects of reduced taxation, that they are by no means confined to the article on which reduction is made. The saving may be expended, not at all in that article, but in some other article of more prime necessity, in which the revenue will be increased. Sir R. Peel himself seemed to expect that a considerable portion of the income-tax would be paid in that way. We believe that no reduction of the duties upon wine (to which he referred) would lead to its consumption among the lower classes, so as materially to benefit the revenue, until they are more cheaply and better fed and lodged, in the articles of corn, and sugar, and timber— the articles which the budget of the late ministry would have brought within their reach. They need, in addition to their meagre fare, the nourishment which wine will not give them, but a pot of porter will. Wine is an agreeable stimulant to the middle-class consumer— it is worthless to the labouring man. As to timber, we may state shortly, that the report on the condition of the hand-loom weavers recommended the lowering of the duties upon Baltic timber, "to a rate which will again allow it to be used for the dwellings of the majority of the people." Sir R. Peel has raised the differential duty from 500 to 1,500 per cent.

We cannot therefore feel very grateful for an alteration which, whatever minor ills it deals with, leaves untented the festering sores which made them almost unfelt. Deeply grieving for the distress of the labouring poor, and above all things anxious to relieve it, we feel no exultation, no delight, in a tariff which taxes highly the chief articles of subsistence, and admits diamonds free.-Much has been said of the value of the concession of principle. It would have been more valuable if it had been more gracious. The monopolists have, it is certain, been driven away from their high ground. But Lot was not driven from Sodom more reluctantly, nor did Lot's wife look back more mournfully on its destruction. The tariff will be a pillar of salt to the end of time.

C. J. F.

(u. c.)

ART. III.-ELECTROTYPE AND ELECTRO-MAGNETISM.

1. Instructions for the Multiplication of Works of Art in Metal by Voltaic Electricity. By Thomas Spencer. Glasgow: Griffin & Co., and Tegg, London. 1840.

2. Electrotype Manipulation, Part I., being the theory and plain instructions in the Art of Working in Metals, by precipitating them from their solutions through the agency of Galvanic or Voltaic Electricity. By Chas. V. Walker, Hon. Sec. Lond. Elec. Soc. & Sons, Foster Lane. 1841.

Knight

3. Do., Part II., on Electro-plating, Electro-gilding, and Electroetching, with an account of the several applications of Electrotype in the Arts.

4. Elements of Electro-metallurgy, or the Art of Working in Metals by the Galvanic Fluid: By Alfred Smee, F. R. S. Second edition. Palmer, Newgate St. 1842. Parts I., II. and III.

5. Familiar Instructions in the Theory and Practice of Electro-gilding and Silvering; also Instructions in the Formation and Theory of Voltaic Batteries, illustrated by numerous engravings. By J. Sturgeon. London. Sherwood & Co. 1842.

SINCE the general adoption of the inductive principle, it is no longer an uncommon thing to witness the rise of some new science, or the equally unexpected extension of one which had been long supposed to

have reached its utmost limits. Could those judges who convicted natural-philosophers of witchcraft, now rise at the wand of some real wizard, to witness the discoveries and inventions of only thirty years, we should be less astounded, we think, at their strange visit, which we should probably look upon as simply another new fact to be investigated, than they would be at our acquisitions. What, for instance, would they think of the magical phenomena of electricity, its endless modes of exhibition, the vast number of natural enigmas which it explains, its present physical uses to mankind?

The works before us treat of the novel, and, to many minds enchanting, subject of electro-metallurgy. We purpose, in this article, to consider more particularly the work of Mr. Smee, and then to offer a few remarks on electro-magnetism.

"Electro-metallurgy" is a term first used, we believe, by Mr. Smee; by which is meant, the art of working in metals by means of the galvanic fluid. Precipitation by this means, is a more desirable method of working those metals, for particular purposes, than the processes hitherto employed in the arts. England and Russia made the twin discovery. Professor Daniell had observed that every scratch on the copper-plate of his excellent battery, was faithfully depicted by the deposit of virgin copper; and in 1839, Mr. Spencer, of Liverpool, following out the idea, which Mr. Daniell had unaccountably neglected to do, endeavoured to produce deposited lines in relievo, after which he succeeded in taking fac-similes of several coins. This ingenious application of a known fact, (for it was no more,) soon attracted general attention, and after the incredulity had subsided, which always rises upon a striking answer to the "quid novi?" of the public, the mass of inquirers split into two distinct bodies, one of which regarded it as an elegant plaything, good for everything but a white hand, and the other as a prelude to magnificent practical results, and an exhaustless storehouse of inventions, to be patented by whomsoever, in a general scramble, should first catch hold of them. The science has been benefited by both; a strong demand for galvanic materials, and a taste for the products of " electrotype," being created by one party, and much knowledge elicited and several trades originated by the other. So early as 1841, several manuals for different classes of operators went to press, the most conspicuous of which are Mr. Walker's little tract on " Electrotype Manipulation," and the first edition of Mr.Smee's "Electro-Metallurgy." This last, considering the state of the science at that period, and Mr. Smee's professional engagements, is certainly a masterly production. The work, a second edition of which is now publishing in parts, is

divided, after an old fashion, into "books ;" and the method introduced by Dr. Faraday, of numbering the paragraphs throughout, has been adopted. The first book contains a cursory view of the modes in which voltaic electricity is generated, and the leading phenomena exhibited by it; an account of the different batteries, (of which more hereafter) and a comparison of expense, a very important item in this science, to which in some respects we demur.

Since the author has introduced extraneous matter, we rather wonder that he should wholly have neglected a question of great and general interest, and which strictly belongs to "Electro-metallurgy,"-the operation of terrestrial voltaics in the production of mining veins. Any homogeneous substance is found, under proper circumstances, to exhibit galvanic effects towards every other substance; with respect to some it will be positive, and to others negative. If the substance be not homogeneous, but a blended mass, there will be much neutralization occasioned by the multitudinous galvanic circuits of its component masses; but if put in chemical arrangement with another substance, similarly constituted but of different materials, these two will in their total action respectively take characteristic and opposite electrical states, and represent poles of a battery, large in proportion to the amount of electricity generated by them. This is exactly the case in the bowels of the earth: one vast tract of land is superimposed upon a bed of different character; if then chemical action take place between the two, however slight, a current of electricity is set in motion, most probably of very low tension, and very long duration. Now, it has been shown by the experiments of Crosse, Fox, Becquerel, and others, that such a current will throw down a great variety of metallic and other substances from their solutions, in regular and beautiful crystals; by this means, several ores have been imitated to such perfection, as to leave little doubt, that, whatever be the actual origin of metallic veins, this is a possible one. If we further consider the thermo-electric state in which all bodies appear to one another, and the theory of Faraday, (to those who receive it,) that conduction and induction are identical, it will no longer be surprising that, to the subtle agent under discussion, a power should be attributed capable of acting on the earth's crust to an almost unlimited extent. It has been ascertained that a railroad engine, blowing off its steam, so modifies the atmosphere, that, on holding an insulated metal rod with a metallic brush at its extremity, in the aqueous vapour, sparks of "machine electricity" may be taken by the knuckles, which are sometimes four inches in length, and very rapid; what then must be the quantity disturbed,

when such a jet as the crater of Mount Etna drives up vapour too hot to scald, mingled with ignited gases, to the height of ten thousand feet, more or less? The varied means already discovered of setting at work that subtile something, be it cause or effect, which we call electricity, lead us strongly to suppose that there may be hundreds of methods still unknown, by which its operations may be most advantageously elicited. It would be the story of Newton's apple over again, to relate the origin of the science of galvanism. The remark made by a lady at the dinner-table to her husband, that the frogs he was eating moved convulsively during the kitchen manipulation, led to the discovery of the science. It would have been an improvement in Mr. Smee's work, had he given a slight sketch of the history of his subject.

The second book is by far the best and most important in the whole work. The first chapter treats of the apparatus required for the reduction of metals. These are divided into two classes, which may be recollected by the names of Daniell and Jacobi. But let us hear our author.

Fig. 1.

"Of the various forms of apparatus," says Mr. Smee, (paragraph 108,) "which may be used for the precipitation of the metals, the most simple is Daniell's battery, having a porous earthenware tube, to contain the acid and zinc, whilst the negative metal, which is usually a mould, is placed externally to this, and connected by a piece of wire to the zinc. Thus, for instance, take a pound pot and half fill it with a solution of sulphate of copper (s); in this place the earthen vessel (P) with the dilute acid (A), and zinc (z), and this constitutes the whole of the present form of apparatus; for, when we desire to make an electro-medallion, it is only necessary to place one or more casts in the outer vessel (m, m) connected by a wire with the zinc, and then action will immediately commence. Any number of moulds can be placed in the outer vessel, provided they can radiate to the zinc. Saturation of the liquid may be preserved by suspending some of the salt in a linen bag over the mould. This form is objectionable, because the salt of zinc speedily passes through to the outer vessel; but it has the advantage of allowing the mould to be placed vertically, in which position it is much less liable to have particles of dust settling upon it. There is no limit to the size of this outer vessel; for a water-butt, a tank, or even a lake naturally impregnated with sulphate of copper, would form glorious apparatus for the electro-metallurgist.". Pp. 59, 60.