HOW TO MAKE A BATTERY?

One of the best batteries for electro-plating purposes is the ordinary gravity battery, of which there are various styles, all of them, however, being made on the same general plan.
To construct a battery of this kind, procure two or three pieces of sheet copper five or six inches long, and about two inches wide and fasten them together by means of a copper rivet through the center; to the end of one of the strips fasten a copper wire about a foot long by means of another copper rivet. The wire must be well insulated except at its two extremities, in order to prevent its being corroded at the surface of the solution.
India rubber is the best substance for this purpose and is generally used in batteries of this description, but where wire already coated with rubber cannot be procured, a very good substitute may be obtained by wrapping the wire carefully with tarred twine and giving it a final coating of melted beeswax, containing a very little lard.
The zinc electrode is more difficult to make, and where it is convenient it will be more economical to buy them. They are made in a number of shapes, the object being to obtain an electrode exposing the largest amount of surface to the action of the solution for a given weight of metal, and a the same time to be of such a shape as to allow the bubbles of hydrogen gas formed by the action of the battery to escape freely.
A very convenient form is that of a wheel with six spokes, the "hub" projecting upward about two or two and a half inches with the connecting wire cast in the center of it. This wire should be from from from four to six inches in length.
Zincs of this kind are suspended in the solution by passing the wire through a hole in a small flat piece of wood long enough to reach across the vessel, and is fastened to it at the proper height by means ol a small clamp of any kind, or by simply taking a turn of the connecting wire around the supporting stick. A very good clamp for securing the zincs in position may be made by drilling a hole large enough to admit the wire, throug a small piece or block of metal, and then drilling another hole at right angles, and intercepting the first one, and fit-ting it with a screw, and is used by slipping it over the connecting wire until it rests on the wooden support, and fastening it to the wire by (means of the screw.
Zincs are often cast in the form of a thick ring with a hook shaped projection of the same metal extending upwards about three inches and at right angles with the ring. This zinc is used by attaching it to the jar by simply hook ing it over the edge. The top of the "hook" has two holes drilled in it, intercepting each other, one of them being fitted with a set screw for clamping the connecting wire.
There are several other forms of zincs, but these two we have described embody the main features of all the others and of these two we think the first is the best on account of the larger amount of surface exposed and the more economical distribution of the metal.
The dimensions of a well proportioned zinc should be from five to six inches wide, one inch to one inch and a half high, and the spokes and rim about three-eighths to half an inch thick.
The jar for containing the battery should be about ten inches high and from six to seven inches wide, with straight sides and flat bottom, and may be of either glass or earthen ware.
To set the battery in operation, fill the jar with water to within two inches of the top and add one pound of sulphate of zinc. When it is all dissolved take the copper electrode and bend the strips outward until their ends are all about equally distant, and place it in the bottom of the jar ; then add a small handfull of sulphate of copper and suspend the zinc in the solution, about two inches above the copper, and in a short time the battery will be ready for use. When using more than one jar or cell of bat¬tery at one time they should be connected together by attaching the zinc of one jar to the copper of the next, the zinc of the second to the copper of the third, and so on, leaving the copper of the first and the zinc of the last jar for connecting with the wires leading from the plating solution.
When not in use the terminal wires should be connected together in order that the battery may continue to work, otherwise the blue solution will gradually raise, and in a few days time surround the zinc and soon destroy it. When the blue solution has almost disappeared add a few crystals of sulphate of copper. After being in use for some time the solution becomes saturated with sulphate of zinc, which will creep up the sides and over the top of the vessel and greatly impair its working. When this is ob¬served draw off about a pint from the top of the solution, and replace it with water, taking care not to stir the solution.
This form of battery is termed the "gravity battery" because the two solutions which are employed in it, sulphate of zinc and sulphate of copper, are separated, but allowed to touch each other by taking advantage of the difference in their weights, the sulphate of copper solution being the heaviest, remaining at the bottom sur rounding the copper electrode, and the sulphate of zinc, being the lightest, remains at the top and surrounds the sine.
After this battery has been in use five or six months the zincs will require renewing, the copper in the meantime having greatly in¬creased in size, the copper of the sulphate of copper havin been deposited upon it, while the liberated sulphuric acid attacked the zinc, forming sulphate of zinc. When the deposit upon the copper has become about a quarter of an inch thick, it should be removed by bending the strip until the deposit cracks. It may then be easily removed by inserting a chisel between it and the original copper strip. Quite a quantity of perfectly pure copper may be collected in this manner, which is valuable, and should be preserved.
The zincs should be taken out at least once a month, and thorougly scraped and cleaned.
This battery is preferred for electro-plating operations on account of the steady, uniform carrent it produces, which is a very important consideration in obtaining a good deposit.
The strength of the current may be varied by raising or lowering the zinc in the solution. When a weak current is desired the zinc should be raised so that but a very small portion of it is immersed in the solution, the greatest strength being obtained when all the zincs are wholly immersed.
This battery possesses a very great advantage over all others, from the fact that it always generates a current of uniform strength during long continued action, which is something that other batteries, although generating a more powerful current, often fail to do. It is also much more easily managed, and requires less care and attention to keep it in good working order, and, in fact, the only objection that can be legitimately raised against it is, that it deteriorates rapidly when not in active service, the blue vitrol solution, raising slowly, but surely, and finally surrounding the zinc, which is quickly corroded and rendered unfit for use until it has been thoroughly cleaned. When there is but little work to do, and the battery forced to remain idle the greater part of the time, the old style "Daniel" battery will probably give the best results. It consists of a strip of copper five or six inches wide and fifteen or eighteen inches long, rolled in the form of a cylinder that will fit the inside of the battery jar loosely. Inside of this copper cylinder is placed an earthenware cup which, in the abesnce of regular porous cups, made especially for this style of battery, may consist of a small unglazed flower pot, the hole in the bottom being securely stopped up. Inside of this porous cup is placed a bar, or better still, a small cylinder of zinc.
To put the battery in operation, fill the outer jar with a solution of blue vitrol, and the porous cup containing the zinc, with a tolerably strong solution of sulphate of zinc, or a mixture of ten or twelve parts of water, to which one part of sulphuric acid is added slowly, may be used instead. The blue vitrol solution must be kept strong, and completely saturated, by carefully observing that there is at all times a few crystals of blue vitrol in the solution, and by adding a small handfull, from time to time, as fast as it is dissolved. The zinc should be supported in some way, and not allowed to touch the sides, or bottom of the porous cup. This is usually accomplished by laying a small stick across the porous cup, and suspending the zinc from it by the connecting wire.
This battery generates a steady and uniform cnrrent, but of less strength than that generated by the "Gravity" battery. When the battery is to remain idle any considerable length of time, the zincs and coppers should be taken out, washed and laid away, and the porous cups removed and the liquid they contain poured

Into a bottle and preserved for future use. The fclue vitrol solution may remain in the larger fcutside jar, which should be carefully covered i)ver to keep out the dust.