The following description of the method of coining money is based on a pamphlet, "Mint Processes of the United issued by the Treasury Department. The provesses required for converting the crude metal into money are: (1) Assaying; (2) refining or parting, which reduces the material into ingots or bars of standard pu rity; (3) redwing the bars to coinage ingots by mixing with them the proper amount of copper alloy; (4) coining, or transforming the coinage ingots into money. The gold and silver which is brought to the mint may be in a crude or manu factured condition and is of every degree of ness. The initial proeess, therefore. is to assay the metal, in order to determine both its value and the subsequent minting operations necessary to refine it. This process and the succeeding one of refining are described in the metallurgical articles on GoLo and SiLvEn and under ASSAYING. The bullion thus purified is reduced to bars. a gold bar usually weighing 60tHI ounces. worth about $8000. It is now ready to be used for industrial purposes, or for the next stage in the coinage proeess.
The consumption of gold and silver in the arts and industries is very great. During the year ending -lune 30, 1S95, gold and silver bars for industrial use, in about equal ratio, were manu factured in the Philadelphin mint and in the assay office at New York to the coinage value of $17.818.5SE Private refineries furnished not less than $5.000,000 more. These bars are 0.999 fine. A depositor may bring crude bullion in any quan tity, of $100 or more in value, and receive either fine gold bars or coin, at his option, a charge of not more than five cents an ounce being made for assaying and refining. For the silver alloy in the gold the owner will In• paid either in silver bars or silver dollars, at the market value of silver.
If the gold or silver is to be coined into money the pure bars must be mixed with cup per alloy; standard gold coin is composed of 75 parts of copper and 25 of silver in 1000. The law allows a slight variation from this standard, but in actual practice a single gold coin rarely varies more than 0.03 per cent. from the standard, either way, and a silver coin, which is much more diflic•ult to manage, not more than 0.1 per cent., while the average is almost exactly correct. Weighed quantities of gold and copper, or of silver and copper, art melted together in a black-lead crucible, the molten metals thoroughly stirred together, and then poured into cast-iron molds to form ingots. These vary in size ac cording to the denomination of the coins to be made from them. The following table, compiled In• William H. Morgan, Coiner of the United States (lint at Philadelphia, gives the sizes and approximate weights of gold ingots: while Chose that arc above weight are filed down. The standard weight for gold coins is as follows: Double eagle, 516 grains; tolerance allowed by law, 0.50 grain. Eagle. .258 grains; tolerance, 0.50 grain. Half eagle. 129 grains; tolerance, 0.25 grain. Quarter eagle, 54.5 grains; toler ance, 0.25 grain.
Next comes the process of milling, or produc ing a raised rim around the edge of the coin, to prevent abrasion. This is accomplished in a milling machine, into which the blanks are placed one by one by hand. The blanks rotate in a hori zontal plane in a groove formed on one side by a revolving wheel and on the other by a fixed segment of corresponding groove. Each piece, as
it passes through this narrow groove, has its edges forced up into an even rim. After an ncaling and cleaning, the coins are now ready for the final process of stamping. The planchet, fed to the press through a ieal tube, is automatically placed in a steel collar, whose inner surface is reedy(' to produce the fluted surface on the milled edge of the coin. Ilere it is firmly Itch] while the dies close upon it with enormous force. producing impressions on The ingot for silver dollar coinage is 1% inches wide, 1.4 inch Hindi. and inches long. The ingots are passed repeatedly between heavy rollers to form them into strips. a process which is called 'breaking down.' After each passage the rollers are screwed tighter, the amount of pressure being regulated exactly by a elock-dial. The strips are annealed during the process to prevent their breaking. The strips. having been greased with tallow. are finally reduced to stand ard thickness by drawing out in draw-benches by a process similar to that of wire-drawing. f See WIRE.) Having been drawn to the required weight, which is ascertained by weighing blanks cut from each end. the strips are cut into planchets, by means of a steel punch. working into A matrix. ( See 1)IES .1ND DIE-SINKtsn.) These planchets tire now cleaned and carefully sorted. all that are not perfeet or are under the standard weight being set aside to be remelted, both sides of the coin. (This process and the preparatory one of engraving and stamping the dies are described under DIES AND Dm-SINKING.) The pressure required to produce a clear, s:.•trp impression on the various gold coins is as fol lows: Double eagle, 175 tons; eagle, 120 tons; half eagle, 75 tons; quarto• eagle. 40 tons. Double eagles and eagles are struck at an average rate of 80 per minute; half eagles and quarter • eagles at a rate of lot! per minute. The pressure required for stamping silver coins is: Dollar. 150 tolls; half dollar. 110 tons; quarter dollar. SO tons: dime, •10 tons. The first three are struck at an average rate of SO per niMute, and dimes at the rate of 100 per minute.
The total coinage of gold by the mints of the rnited States from 1792 to June 30, 1900, was $2.167,0SS.113, of which it is estimated that $923.653.642 is still in existence as coin in the United States. while the remainder represents the excess of exports over imports and the amount consumed in the arts. (See circular No. 113, issued by the United States Treasury Department, July 2, 1900.) The amount of sil ver coinage for the same period is given in the accompanying table.
The coinage for 1900 in the mints of the United States was the largest on record, amount ing to 184,373,793 pieces, of the value of $141, 351,960.36. A significant feature was that the increase was in subsidiary coins, due prob ably to the unusual activity of retail trade throughout the country. The seigniorage on the coinage of silver dollars, subsidiary and minor coins during the year amounted to $10,236,302.50. (See SERINuntAGE.) Consult the annual reports of the Director of the Mint, and also the various pamphlets on coinage issued by the Treasury De partment at Washington.