When the voltaic current is transmitted through metallic solutions, the metallic oxides are in certain cases decomposed, so that the pure metal is deposited upon the cathode. For example: let two pieces of clean platinum be immersed in a solution of sulphate of copper; and let the electric current be transmitted through the solution, so that these platinum plates may form the electrodes. The consequence will be the precipitation of pure metallic copper upon the catelectrode, while the anelectrode will remain clean. The texture of the deposited copper varies with the power employed, and with the temperature and strength of the solution; so that it may be obtained hard, brittle, and crystalline; or malleable and tough, according to the manipulation of the performer.

"When we subject any metallic solution to the action of the voltaic current, the metal itself will be reduced, although not always in the same state. Thus, if we dip a knife in a strong solution of sulphate of copper, bright metallic copper will be deposited; but if we use a piece of zinc, a black mass of copper will be thrown down. Again, introduce a piece of zinc into an ammoniacal solution of sulphate of copper, and the reduced copper will be bright; whilst, if we dip iron into a very dilute and acid solution of the sulphate, black metal will be reduced. It is doubtful whether the metal in these cases is reduced by single elective affinity, or whether a galvanic action causes the deposit. Be this, however, as it may, the same metal may, under different circumstances, be reduced in different states."Smee, p. 113.

On the one hand, the strength of the metallic solution very materially influences the nature of the deposit. From a saturated solution of sulphate of copper, for instance, crystalline copper is deposited; if we dilute this solution with two to four times its bulk of water, the metallic deposit will be ductile and malleable: if the solution be very greatly diluted, the metal will be thrown down under the form of a black powder.

"If we examine the converse of the experiment, and take a solution of sulphate of copper (which should be acidulated to make it a better conductor,) and use successively, first one very small battery, then two or three batteries arranged in a series, and lastly, a very intense battery, we shall find that, with the same solution, we can obtain by these means, first a crystalline, then a reguline, and then a black deposit.... The laws which regulate the deposit of every metal appear to be the same; and, although very simple, yet have cost me much labour for their development ... Law 1. The metals are invariably thrown down as a black powder, when the current of electricity is so strong in relation to the strength of the solution, that hydrogen is evolved from the negative plate of the decomposition cell... Law 2. Every metal is thrown down in a crystalline state, when there is no evolution of gas from the negative plate, or no tendency thereto; . . that is, when the strength of the metallic solution is so great, that, either electricity of a much greater tension must pass, or the solution must be rendered of more easy decomposition, before gas would be evolved. Law 3. Metals are reduced in the reguline state, when the quantity of electricity in relation to the strength of the solution is insufficient to cause the production of hydrogen on the negative plate in the decomposition trough, and yet the quantity of electricity very nearly suffices to induce that phenomenon."-Smee, pp. 114-118.

Mr. Smee has devoted the concluding portion of his treatise to a consideration of the processes of electro-gilding, reduction of metals by galvanism, the electrotype, and galvanic etching.

For the art of gilding upon silver and brass by means of electricity, we are indebted to M. De la Rive, who was led to it by witnessing the very deleterious effects upon the workmen of the process known as "water-gilding;" in which the article to be gilt having been covered with an amalgam of gold is exposed to the heat of a clear charcoal fire, by means of which the mercury is driven off and the gold remains adherent to the surface. The evils attendant on this process from the mercurial vapour, are avoided in the process of electro-gilding; where, according to the method patented by Elkington, after the articles have been properly cleansed by a weak acid, they are immersed in a hot solution of nitro-muriate of gold, to which a considerable excess of bicarbonate of potash has been added. They thus receive, in the course of a few seconds, a beautiful and permanent coat of gold. With regard to this process, it has been supposed that the metal to be gilt is dissolved in proportion to the amount of gold deposited; that the deposition of the gold prevents the further solution of the metal; and, consequently, that only a very thin coat of gold can be obtained. Mr. Smee, therefore, gives the preference to a process in which the gold is precipitated from a solution of the auro-cyanide of potassium by means of a single battery. By this process the operator can regulate the thickness of the gilding, carrying it to any extent he pleases; and, by varying the rapidity of the deposition, he can obtain the gold under different forms. A rapid deposition produces a bright surface; but if reduced very slowly the metal will assume the beautiful frosted appearance of dead gold.

Of all the applications of voltaic electricity to the purposes of art, the electrotype is the most interesting and important.

"Electro metallurgy may be said to have had its origin in the discovery of the constant battery by Professor Daniell, for in that instrument the copper is continually reduced upon the negative plate. In his first experiments, Mr. Daniell observed, on removing a piece of the reduced copper from a platina electrode, that scratches on the latter were copied with accuracy on the copper. In this experiment we have the electrotype. But the author, in the first paper, detailing his experiments, having devoted all his attention to the construction of the battery itself, this valuable fact attracted but little of his notice.

"It was but a short time after the discovery of this battery, that Mr. De la Rue experimented on its properties. In a paper printed in the Philosophical Magazine for 1836, after describing a peculiar form of battery which he adopts, the following remarkable passage is found: "The copper plate is also covered with a coating of metallic copper, which is continually being deposited; and, so perfect is the sheet of copper thus formed, that, being stript off, it has the counterpart of every scratch of the plate on which it is deposited.' This paper seems to have attracted very little attention; and, what seems still more singular, the author, although well qualified NO. XXXI.-N. S.

K

from his scientific attainments to have applied these facts, never thought of any practical benefit to which this experiment might lead.

"In this state the subject remained till October, 1838, when Professor Jacobi first announced that he could employ the reduction of copper, by galvanic agency, for the purposes of the arts. His process was called galvano-plastic. Immediately upon his process being announced in this country, in 1839, Mr. Spencer stated that he had executed some medals in copper, to which the public afterwards gave the name of electrotypes, or voltatypes, or, what is better, electro-medallions. . . . The next discovery, which is fully equal in value to the idea of the electrotype itself, was made by Mr. Murray. He found out that non-conducting substances might have metallic copper thrown down upon them by previously applying black lead.-Smee, pp. 17—21.

One of the greatest hindrances to the art of copper-plate engraving has been the difficulty of procuring good and pure metallic plates. This difficulty is now entirely removed. A prepared copper-plate with a good surface may have copper deposited upon it by voltaic agency, so that the deposited plate will have the same perfect surface, with the additional advantage of consisting of pure copper. Minute directions will be found in Mr. Smee's work. The practical electro-metallurgist may also consult with advantage Jacobi's Die Galvanoplastik, Petersburgh, 1840; and Annales de Chimie et de Physique, September, 1840, tom. lxxv.

"Engraved plates were not employed till the fourteenth century, but now their uses are manifold. To hand down to posterity, and to diffuse among the multitude, copies of the choicest pictures and other works of art, are their most prominent applications; but they do not constitute a tithe of the purposes for which engraved plates are required. The great consumption now for these plates is at the potteries; for almost every common dinner service, and every piece of pottery, has its design given by a copperplate. The device is deeply cut in the copper, and then it is printed on a piece of thin paper; but the impression is printed with a composition of arsenite of cobalt instead of the ordinary ink. The paper is then pressed upon the pottery plate before it is glazed, in order that the ink may adhere to it; after which the paper is carefully washed off. The pottery plate is next glazed, and is then ready for use.

"The electrotype promises to improve, materially, the patterns of our otherwise unrivalled pottery; for the expense of engraving valuable plates has hitherto been such, that, on account of the small number of copies they will afterwards print, their application has been necessarily prevented. Now, if a plate cost originally a thousand guineas, an infinite number of duplicates could be taken from it by the electrotype; and in this way the expense of every common dinner-plate would be the same, whether the ordinary blue-and-white service were used, or plates and dishes were embellished with copies of our finest works of art, the most exquisite scenes of nature, the most elaborate machinations of fancy, or the most intricate specimens of execution.

"A second extensive application of copper-plates is to be found in the manufactories of the calico-printers. The copper-plate is first engraved and bent round so as to form a cylindrical roller, and then the two edges are soldered. By various contrivances the die is placed by other rollers into the hollow of the engraving, when the calico to be printed passes under the roller by the force which the roller itself exerts from the revolution imparted to it by a steam engine. In this way twenty or thirty yards of calico can be printed in a few minutes."-Smee, pp. 270, 271.

The multiplication of wood-cuts by means of electrotype processes is very promising. The vigour and delicacy, the precision and softness, of modern wood-cuts is surprising, and the durability of the blocks is extraordinary, one hundred thousand impressions having been taken from the same block; but yet, the multiplication of these by means of the electrotype is often desirable. Mr. Smee has given an interesting print, at page 277, of a dog's head, designed by the younger Landseer, a lad twelve years of age; the clichée of which was executed by Branston, and the electrotype by De la Rue. The "clichée," we may observe, is simply the reverse impression; the intermediate copy by means of which the ultimate plate is made the same as that from which the design was first taken.

The yet more recent art of glyphography is remarkably simple and useful.

"The term glyphography is derived from two Greek words, yλupw I engrave, and ypápew to draw; and signifies that art by which an engraving is produced by the simple mode of drawing; or, in other words, drawing and engraving, which have hitherto been two distinct operations, are here combined in one. Hence its merits, and vast importance to every artist, seeing that by its aid he becomes the engraver of his own work as much as he could by the practice of etching, but with this difference, that here his effect is as immediately conspicuous as though he were using a black-lead pencil on paper."-Glyphography, p. 5.

In this process, an ordinary plate of copper, prepared as usual for engravers' use, is taken, and blackened with sulphuret of potassium. It is then warmed, and coated with a very thin layer of a white composition resembling wax in nature and appearance. By means of various tools, which need not be described here, this composition is cleanly cut through by the artist, who sees at once the effect he produces, in consequence of his obtaining, as in the case of the lead-pencil, a black drawing upon a white ground. After careful inspection through a powerful lens, the plate is submitted to the action of a galvanic battery, by means of which the required deposition of copper is effected, and a new electrotype plate is obtained.

"Of the value of electro-metallurgy to the arts and manufactures, even in its present state, there can be no doubt. It may, indeed, be a matter of conjecture to what extent this art may be ultimately carried out, or to what other purposes it may be applied in years to come; but, were it never to be applied otherwise than it has already been, no one could deny that it is a most valuable acquisition; in short, we may safely assert, that no single discovery ever presented capabilities at once so many, so various, so interesting, or so valuable.

"Doubtless the galvanic fluid will, before long, be as important to the manufacturer as the heat of a furnace. At present, a person may enter a room by a door having finger-plates of the most costly device, made by the agency of the electric fluid; the walls of the room may be covered with engravings printed from plates originally etched by galvanism, and multiplied by the same force; the chimney-piece may be covered with ornaments

made in a similar manner. At dinner, the plates may have devices given by electrotype engravings, and the salt-spoons gilt by the galvanic fluid. All these, and many other applications, we may have at present; but we must still look forward to the most important properties of the electric current derived from the galvanic battery: for, although great and glorious are the triumphs of science detailed in this work, yet the prospect of obtaining a power which shall supersede steam, exceeds in value all these applications." -Smee, pp. 295-300.

Mr. Smee's raptures are excessive; but the subject is unquestionably one of considerable interest. The applications of voltaic electricity are of great practical utility; and the principles of the science, when ripened and expanded, will form a valuable addition to the ever-growing body of physical truth.

The Poetical Works of Robert Southey, collected by Himself. In 10 vols. London: Longman, & Co. 1838.

Goëthe,

To thinking minds, time is seldom so impressively marked, its clock seldom tolls so sadly and solemnly, as by the successive removal of the great men of an age. The constellation which ushered in the present epoch, is going out one by one. Scott, Byron, Coleridge, Lamb, have departed, and now Southey has gone after them. Wordsworth, indeed, remains yet a little while, but he is now bereft of all his great companions; of all those with whom his name is for ever associated. There is something, we say, singularly sad and solemn in these departures. Its great men seem the essential features of an age, and when they are removed, a chill comes over us, the ground seems taken from under our feet, we feel as though a change of dispensation were at hand, an untried and unknown future opening before us.

There are few men to whose death more of this interest attaches itself than to him whom we have just lost. If Southey was not the foremost man of his time, he was perhaps the most bound up with that time, of all our men of letters. No man of intellectual pursuits in our day shared so largely in its feelings and struggles, and as the term of his life spanned its principal events and changes, he became a partaker in its most striking vicissitudes. There is nothing for a serious mind to scoff at, nothing that can furnish a legitimate sneer at Southey, in a comparison of his early Jacobinism and subsequent Toryism. In his case the whole process and progress was that of an earnest and noble mind, equally unworldly, though not equally temperate and far-seeing at its commencement and at its termination; and therefore, in the whole, we only read a deep and interesting lesson.