Rensselaer Union, Volume 7, Number 3, Rensselaer, Jasper County, 8 October 1874 — Coining. [ARTICLE]

Coining.

The operations conducted at the private mint at Birmingham, England, ns we learn from an interesting report in Iron, are as follows: The raw material consists of immense quantities of copper in ingots for bronze coinage, and “ cakes” of the same metal for copper coinage. The metal used for -tho bronze epins is composed of "ninetyfive parts of •opper, four parts of tin, and one part of spelter or zinc. The metal is first taken to the casting shop and there melted and run into molds of the required length. The processes of casting being almost the same for ali purposes there is no need of givinlg a minute or) detailed description of the operation. . ■ . The strips of metal when cast are taken to the rolling mills. The slabs of metal are first passed Through the heavy revolving cylinders, and the pressure is to great to which they are subjected that they- are rolled into much longer and, of course, thinner''strips. They are next submitted to the ordeal of lire, and annealed. They are submitted to this process of rolling until the requisite thickness, or rather thinness, is obtained. A slab which is at first only some fifteen inches long is rolled out to six feet in length. It is then placed once more in the annealing oven, “pickled” by'being

passed through acid, then cleaned and scoured. Each slip has- to gauged with the utmost nicety after it has undergone these processes, to ascertain whether itls of equal thickness throughout. After being approved the strips are taken to the cutting-out-room, where they are passed undbr a press, and bits of circular metal of the size required are cut out and dropped into receptacles Beneath. These bits of plain metal are appropriately tailed “ blanks,” and are cut with almost incredible rapidity. One press produces 750 a minute, and in the mint the. number of presses employed are capable of producing over 3,000,000 of blanks a day. After being cut the blanks are tested by being passed through a machine, which is so nicely adjusted that any irregularity or imperfection is detected, and the tares are separated from the w'heat. The blanks w'liich pass successfully through the trial have also to be annealed. For this purpose they are “ put into small iron pots, the lids of which are carefully adjusted, and the junctions stopped with clay, and placed in the oven, where they remain generally about three-quarters of an hour. They are then allowed to cool gradually, passed through a solution of acid, and in their wet condition are placed in a revolving wooden drum, together with a quantity of rough sawdust. The motion of the drum causes the saivdust to escape through small apertures provided for the purpose, and by the time the blanks are dry—usually in twenty minutes —all discolorations have been removed and a uniform bright color attained. They are then ready to receive the finishing stroke —the impression which shall cause them to be universally recognized as tokens of value.” Two dies are required for each coin; the one for obverse, the other for reverse. These are engraved on the best steel, but the original dies are not used in making the impressions on the coins. For this purpose a punch is made, and from this punch the molds by which the the coins are made are taken by pressure. The pressure required for this purpose is at least forty tons. The molds are made on the surface of pieces of steel, the diameter of which is a little larger than the coin to be made. So great is the pressure of the striking hammer that the slightest flaw in the steel used is fatal to the working die, for it comes from under the machine kibiting a large rent wherever the flaw' may be. The importance of this power of multiplying dies will at once be manifest. Sometimes they are destroyed in a few minutes, lasting, we learned, on an average not more than two days; but the original die, which represents a fortnight’s skilled work, remains perfect for the production of other punches to be used in making working dies. The coining is a very simple . process, and is now rendered almost noiseless by improved machinery. In each press is a movable steel slide, in the center of which is a circular hole the size of the die, called a collar. The blanks to be impressed are placed in a long brass tube, called a feeder or hopper. From this feeder one blank drops into the collar with each movement of the slide. It is between the top and bottom, and as the blow is struck both sides are impressed at once