We often see medals and casts of rare and interesting objects, copies of which we like to have by us. To obtain these is not an expensive process; it only requires patience and care. We propose therefore to give such plain directions as will enable any of our readers to make such copies for themselves.

We will take first an instance of a medal, showing perhaps the head of one of the Caesars, or a medal struck to commemorate some great event.

First, you must decide in what material you would like to have your cast. This must, in a measure, depend on the delicacy of the work you have in hand, and whether the impression is in high relief or not.

The most delicate impressions are obtained in wax, gutta-percha, and sulphur, any of which substances can be used for making moulds. Suppose you have a medal in copper which you require to copy. You must first of all smear the face of the medal with a little sweet-oil, - olive oil. You can put this on with the tip of a feather, and then rub it well over with a piece of cotton-wool, so that the oil goes into every crevice, and none collects anywhere. Now surround the medal with a slip of cardboard about ½ inch wide, by putting the medal flat on a board, and wrapping the slip of cardboard closely round it; and while holding it tightly, drop a piece of melted sealing-wax between two portions of the card that overlap, for the slip of card must be more than long enough to go once round. You will now have the medal tightly surrounded by a card, that will receive any fluid substance that may be poured into it. We will now take some fine plaster of Paris, which you can buy at a stone-mason's, or at an Italian's, whose business it is to make "images." Get the finest plaster, and some that has been freshly prepared. It is sold by the pound and costs very little, but the coat varies slightly according to the fancy of the seller. Now for making the mixture of plaster. For this purpose you want a smooth, medium-sized wooden spoon, a small basin, and a jug of clean water. To avoid making a mess, either put a board, or spread a piece of brown paper on the table. Now put a little water into the basin, and put in a small quantity of the plaster; as much as you think you will require for the work prepared. The plaster will sink to the bottom. Pour off the superfluous water, and mix the plaster well; it will have the consistency of cream. Now put in a little of this mixture on to your medal; and with a small stiff brush, holding the brush upright, get the plaster well into all hollows of the medal; then pour in the rest to the depth of about 3/8 of an inch. Lift the whole thing, taking care not to slip off the cardboard, and jerk it sharply on to the board once or twice, to set free any air-bubbles that may be entangled with the plaster; and then allow it to stand without disturbing it for ten or fifteen minutes. You will find by this time the upper surface will be hard, so that you may remove the cardboard. If the plaster is not fully "set," do not lift it off the medal for a few minutes. Freshly made plaster sets quickly, while the older it is the more time it takes to set. The plaster not used may be washed out or thrown away, for it cannot be used a second time. Be sure not to use au iron spoon for mixing the plaster; the cleanest and best is a spoon made of hard wood, and let it be kept for that purpose only.

Having made your mould successfully, you have of course the exact reverse impression of the medal.

To be able to take a plaster cast from a plaster mould, requires that the latter should be prepared so there is no chance of the two hanging together when one is cast into the other. To be sure of this the mould must be well oiled; oil boiled and put on it, so that the mould is almost soaked with it. It must not, however, be allowed to lie on it, so that it fills up any part of the impression. A mould so prepared gets hard, and may be kept for a long time, and if carefully used, a large number of castings may be taken from it. Having prepared the mould, proceed with operations as directed for taking the mould itself. Surround with slip of cardboard; mix your plaster and proceed exactly in the same way.

If you are taking a mould from a plaster copy of a medal or a medallion, where you cannot be allowed to oil the original on account of disfiguring it, you can take a mould in sulphur by the following process.

Place the original plaster medal in a saucer of water, so that the water does not come above halfway up the thickness of the medal. The plaster will absorb the water, and the face of the medal must be watched. Immediately it gets a shiny surface it must be removed so that no water percolates through it and collects on the upper surface. While this is being done, have some roll sulphur slowly melting by the fire; it must melt very slowly or it will not get into a thin fluid, or keep a nice yellow colour.

When this is ready, and you have surrounded the medal to be copied by the slip of cardboard as usual, pour the sulphur on to the face of the medal. Be careful that no air-bubbles are allowed to collect between the sulphur and the plaster. This is not likely if you have the sulphur in the condition of a nice thin liquid, and rap it once or twice rather sharply on the table. Cover it to about the depth of a ¼ inch, then let it stand and cool; it will then get solid. Then lift it off the medal, and if you have successfully carried out our instructions you will have a sharp reverse impression of the original. To save your sulphur mould from the chance of being broken, it is well to back it up with a ½ inch thickness of plaster of Paris, prepared and put on as we have already described.

To take a casting from the sulphur mould, oil its face very carefully, - taking care that none of the crevices and hollows escape this oiling, - which can be done by a piece of cotton-wool. Then surround it with the slip of cardboard, mix. mix the plaster, and go through the same process which we have already described. We have taken scores of impressions by this process.