of the plaster or wax moulds attached to the zinc and immersed in the copper solution in the same manner as described with the penny-piece (page 534), no deposit would be obtained, because neither the plaster nor the wax is a conductor of electricity. Some substance must now be applied to the surface in order to give it conducting power. There are several ways of communicating this property, but the best and most simple for the articles under consideration is to apply common black lead (already referred to) in the following manner:-A copper wire is put round the edge of the medal, or, if wax moulds are used, a thin slip of copper may be inserted into the edge of the mould-or, being slightly heated and laid upon the back, the two will adhere. A fine brush is now taken (we have found a small hat-brush very suitable) and dipped into fine black lead, and brushed over the surface of the medal. The brushing is to be continued until all the face round to the wire upon the edge, or slip of copper forming connection, has a complete metallic lustre. A bright polish is necessary to the obtaining a quick and good deposit.

In brushing on the black lead, care should be taken not to allow any to go upon the back or beyond the copper connection, or the deposit will follow it, and so cause a loss of copper, and make the mould more difficult to separate from the deposit; being, as it were, incased. If the electrotypist takes the labor himself of filing off all the superfluous copper from the edge of his deposited medal, it will do more than any written precautions to teach the necessity of preventing as much as possible the deposit going further than is necessary. When the face of the mould is properly blackleaded, the copper wire connected with it is attached to the zinc plate in the porous cell, and the mould immersed in the copper solution; the deposit will immediately begin upon the copper connection, and will soon spread over every part, covering the blacklead polish with less or more facility according to the state of the solutions and other circumstances to be afterwards noticed. When the deposit is considered sufficiently thick for removing—which, in ordinary circumstances, will require from two to three daysthe medal is taken out of the solution, and washed in cold water, and the connection is taken off. If the deposit has not gone far over the edge of the mould, the two may be separated by a gentle pull; if otherwise, the superfluous deposit must be eased off, and if care be taken the wax may be fit to use over again: but when the mould is plaster of Paris, however well it may be saturated with wax, it is seldom in a condition to use again. If the plaster mould be large and thick, it is advisable to coat the back with wax or tallow, which is done by brushing it over with either substance in a melted state: the mould being cold will not absorb the wax or tallow hence it may be recovered again. The sulphate of copper possesses so penetrating a quality that if the slightest imperfection occurs in the saturation of the mould by wax, the solu Lion will penetrate through it, and the copper will be deposited

upon the face of the object adhering to the plaster, giving to the metal a rough, matted appearance, and seriously injuring it.

USING METAL MOULDS.-The mould in fusible alloy does not require to be black-leaded, but the back and edge must be protected by a coating of wax or other non-conducting material; it may be connected in the same way as the penny-piece (page 534) by putting a wire round its edge previous to laying on the nonconducting substance, such as tallow or wax, which should also cover the wire. Or a slip of copper, or wire, may be laid upon the back and fastened by a drop or two of sealing-wax; the back is then coated: but care must be taken that the wax do not get between the connection and the medal which will prevent deposit. The deposit on this mould goes on instantaneously, the same as over the penny-piece. When sufficiently thick, it may be taken off in the same manner as from the wax mould, the surface having been prepared by turpentine (page 534) to prevent adherence. These moulds may be used several times, if care be taken not to heat them, as they easily melt.

The medals obtained from metallic moulds prepared with the turpentine solution have a bright surface, which is not liable to change easily, but if the mould has been prepared with oil or composed of wax or plaster, the metal will either be dark, or will very easily tarnish. The means of preserving them, either by bronzing or plating with other metals, will be detailed in a subsequent section. PRECAUTIONS ON PUTTING THE MOULDS INTO A SOLUTION.-In putting moulds into the copper solution, the operator is often an noyed by small globules of air adhering to the surface, which either prevent the deposit taking place upon these parts, or, when they are very minute, permit the deposit to grow over themcausing small hollows in the mould, which give a very ugly appearance to the face of the medal. To obviate this, give the mould, when newly put into the solution, two or three shakes, or give the wire attached to it, while the mould is in the solution, a smart tap with a key or knife, or any thing convenient; but the most certain means we have tried, is to moisten the surface with alcoho just previous to putting it into the copper solution. A little prac tice in these manipulations will soon enable the student to avoid these annoyances.

DEPOSITION ON LARGE OBJECTS.--When busts or figures, whether of wax or plaster of Paris, are to be coated with copper, with no other conducting surface than black lead, it is attended with considerable difficulty to the inexperienced electrotypist. The deposit grows over all the prominent parts, leaving hollow places. such as armpits, neck, etc., without any deposit; and when once missed, it requires considerable management to get these parts coated, as the coated parts give a sufficient passage for the current of electricity. It is recommended by some electrotypists to take out the bust, and coat the parts deposited upon with wax, to prevent any further deposit on them; but this practice is not good,

especially with plaster of Paris, for an electrotype ought never to be taken out till finished. Sometimes the resistance of the hollow parts is occasioned by the solution becoming exhausted from its position in regard to the positive pole. In this case a change of position effects a remedy. It may be remarked that when a bust or any large surface having hollow parts upon it, is to be electrotyped, as many copper connections as possible ought to be made between these parts and the zinc of the battery. Let the connections with the hollow parts be made with the finest wire which can be had, and let the zinc plate in the cell have a large surface compared to the surface of the figure, and the battery be of considerable intensity; if attention is paid to these conditions, the most intricate figures and busts may be covered over in a few hours, Care has to be observed in taking off the connections from the deposit, or the operator may tear off a portion of the deposit: if the wires used are fine, they should be cut off close to the deposited surface.

TO MAKE BUSTS AND FIGURES.-Busts and figures, and other complicated works of art, which cannot be perfectly coated with black lead, may be covered by a film of silver or gold, which serves as a conducting medium to the copper. This is effected by a solution of phosphorus in sulphuret of carbon. The operation being patented, we will take advantage of the description given of it in the specification. "The solution of phosphorus is prepared by adding to each pound of that substance 15 lbs. of the bisulphuret or other sulphuret of carbon, and then thoroughly agitating the mixture; this solution is applicable to various uses, and amongst others, to obtaining deposits of metal upon non-metallic substances, either by combining it with the substances on which it is to be deposited, as in the case of wax, or by coating the surface thereof. Any of the known preparations of wax, may be treated in this way, but the one preferred is composed of from 6 to 8 ounces of the solution: 5 lbs. of wax, and 5 lbs. of deer's fat, melted together at a low heat, on account of the inflammable nature of the phosphorus. The article formed by this composition is acted upon by a solution of silver or gold in the manner hereinafter described with respect to articles which have been coated with the solution."*

COATING OF FLOWERS, ETC.-" If the solution is to be applied to the surface of the article, an addition is made to it of one pound of wax or tallow, one pint of spirits of turpentine, and two ounces of India rubber, dissolved with one pound of asphalt, in bisulphuret of carbon, for every pound of phosphorus contained in the solution. The wax and tallow being first melted, the solution of India rubber and asphalt is stirred in; then the turpentine, and after that the solution of phosphorus is added. The solution prepared in this manner is applied to the surfaces of non-metallic substances, such as wood, flowers, etc., by immersion or brushing;

*Repertory of Patent Inventions, 1844.

the article is then immersed in a dilute solution of nitrate of silver, or chloride of gold; in a few minutes the surface is covered with a fine film of metal, sufficient to insure a deposit of any required thickness on the article being connected with any of the electrical apparatus at present employed for coating articles with metal. The solution intended to be used is prepared by dissolving four ounces of silver in nitric acid, and afterwards diluting the same with twelve gallons of water; the gold solution is formed by dissolving one ounce of gold in nitro-muriatic acid, and then diluting it with ten gallons of water."

We have frequently repeated the operations described by this patentee with entire satisfaction, and were enabled to cover every variety of surface with great facility.

The solutions of silver and gold, prepared as above, will last for a long time, and do a great many articles. When it is convenient it is best to use both solutions. The connecting wire should first be attached to the article to be coated, before being dipped into the phosphorus solution, but connected at such parts as will not hurt the appearance of the object by leaving a mark when it is taken off. Care should be taken not to touch the article with the hands after it is dipped into the solution. The object supported by the connections is immersed in the phosphorus solution, where it remains for two or three minutes. When taken out it is dipped into the silver solution, and as soon as the surface becomes black, having the appearance of a piece of black china, it is to be dipped several times in distilled water, and then immersed in the solution of protochloride of gold about three minutes: the surface takes a bronze tinge by the reduction of the gold. It is next washed in distilled water by merely dipping, not by throwing water upon it. The wire connection is now attached to the zinc of the battery, and then the article put into the copper solution, and in a few minutes the article is coated over with a deposit of copper. A thin copper surface may thus be given to small busts or figures without sensibly distorting the features by want of proportion.

FIGURES FROM ELASTIC MOULDS.-When taking a wax cast from the elastic mould, described in page 544, we prefer the phosphorized mixture. After taking out the mould it is only neces sary to make the connections, and pass it through the gold and silver solutions, as described, and then to connect it with the battery.

We may also mention that the principal object of making copper moulds by this process, in the manufactory, is not to make facsimiles in copper, but to make articles of solid silver or gold. Copies of highly wrought work, either chased or engraved, or of articles, duplicates of which cannot be obtained, or of which the workmanship is costly, may by this means be made in solid silver or gold, at little more expense than the cost of the metal. Having obtained the copper mould, silver is deposited in it to any thickness, and the copper dissolved off. However. an extensive trade

is now being carried on in figures and other works of art deposited in copper and then bronzed, which gives them an appearance often not much inferior to that of antique works of the highest art.

ELECTROTYPES FROM DAGUERREOTYPES.-What may be justly termed the perfection of electrotyping, is the production of elec trotypes from daguerreotypes. The daguerreotype picture being taken, a small portion of the back is cleaned with sand-paper, taking care not to allow any thing to touch the face; a little fine solder is placed on this part; a piece of flattened wire, also cleaned, is placed upon the solder, the whole moistened with dilute muriatic acid, or chloride of zinc. The wire is now held over the gas or a lamp about half an inch from the plate; the heat is transmitted through the wire to the solder, which melts, and the wire is soldered to the type; the back is then protected by wax, and the daguerreotype is now put into the copper solution in the same manner as a medal; the deposit proceeds rapidly, and when sufficiently thick the two easily separate, and an impression of the picture is obtained from the daguerreotype with an expression softer and finer than the original; several electrotypes may, with care, be taken from one picture. The electrotype may now be passed through a weak solution of cyanide of gold and potassium, in connection with a small battery, and thus a beautiful golden tint be given to the picture, which serves to protect it from the action of the atmosphere; but they should also be protected by a glass, which may be fixed on in the manner pointed out in another sec tion. The most successful operators that we have known in this and every other department of electrotyping are Dr. Thomas Paterson, of Glasgow, and Mr. Bawtree, of London.

DEPOSITING BY SEPARATE BATTERY.-Having described, so far as we know them, the best and most simple means of obtaining moulds, and their preparation for receiving the deposit of the metal, we return again to the management of solutions and batteries, and the application to other metals besides copper.

Although in our account of the porous or single cell system (page 533) we have recommended it as the best and most economi cal for electrotyping, still many eminent electro-metallurgists prefer using the battery system; and indeed there are solutions of copper and of other metals to which the porous cell system cannot be ap plied, from the nature of the solution and the necessity of intensity to decompose them.

While depositing upon a mould by the single cell, let the wire which connects them be cut in the middle, and a mould be attached to the end of the portion remaining upon the zinc plate, and a small plate of copper to the end of the wire remaining upon the mould in the copper solution, and let these two be put into a second vessel containing a solution of sulphate of copper. The action between the zinc and medal in the double or first cell will go on as before—namely, the electricity passing through the porous cell and the solution to the medal; but on returning to the zinc it must