Mint

Mint (Lat. moneta), an establishment for making coins or metallic money (see MONEY). The early history of the art being traced under the head Numismatics, the present article is mostly confined to a sketch of the constitution of the British mint, and of the modern processes of coinage as there followed.

In Canute's laws, an officer called a 'reeve' is referred to as having some jurisdiction over the mint, and certain names which, in addition to that of the sovereign, appear on the Anglo-Saxon coins seem to have been those of the moneyers, an important class of functionaries, who were, until the operations of coinage were undertaken by the state in 1850, responsible for the manufacture of the coin. Besides the sovereign, barons, bishops, and the greater monasteries had the control of mints, where they exercised the right of coinage, a privilege enjoyed by the archbishops of Canterbury in the reign of Henry VIII., and by Wolsey as Bishop of Durham and Archbishop of York. After the Norman Conquest the officers of the Royal mint became to a certain extent subject to the authority of the exchequer. Both in Saxon and Norman times there existed, under control of the principal mint in London, a number of provincial mints in different towns of England; there were no fewer than thirty-eight in the time of Ethelred, and the last of them were only done away with in the reign of William III. The officers of the mint were formed into a corporation by a charter of Edward II.; they consisted of the warden, master, comptroller, assay-master, workers, coiners, and subordinates. Coining at the Scottish mint in Edinburgh ceased with the Union; but the office of master of the mint was not incorporated with the English one till 1817.

The seignorage for coining at one time formed no inconsiderable item in the revenues of the crown. It was a deduction made from the bullion coined, and comprehended both a charge for defraying the expense of coinage, and the sovereign's profit in virtue of his prerogative. In the reign of Henry VI. the seignorage amounted to 6d. in the pound; in the reign of Edward I. it was 1s. 2½d. By 18 Car. II. chap. 5, the seignorage on gold was abolished, and it has never since been exacted. The 'shere' or 'remedy,' as it is now called, is an allowance for the unavoidable imperfection of the coin in regard to both standard weight and fineness.

The function of the mint, so far as concerns the standard gold coinage, is to receive gold in ingots from individuals, and return an equivalent weight in sovereigns. But, in point of fact, gold is now exclusively coined for the Bank of England; for, although any one has the right to import gold into the mint for coinage, receiving an equivalent weight of sovereigns at the rate of £3, 17s. 10¼d. per oz. standard, after a sufficient delay to allow of the gold he imports being converted into coin, he can at once receive payment on presenting his bullion at the Bank of England at the slightly lower rate of £3, 17s. 9d., and the additional 1¼d. offered by the mint is not found sufficient to compensate for the necessary delay which occurs.

Silver, which was formerly a legal tender to any amount, has, by 56 Geo. III. chap. 68, ceased to be so. That act provided that each troy pound of standard silver should be coined into sixty-six shillings, and, since this exceeds the price at which the metal in its uncoined state can be purchased, it follows that the coinage of silver is a source of profit to the state. When the price fell to 42½d., this profit, or seignorage, amounted to no less than 54 per cent., and even at 5s. per ounce there remains a profit of about 10 per cent. It should, however, be borne in mind that this 'token' coinage is only a legal tender to a limited amount (forty shillings), whereas gold coin is legal tender to any amount. The profit derived from the bronze token coinage is proportionately even greater. The seignorage, which was formerly retained by the master of the mint to defray the expense of coinage, has since 1837 been paid to the credit of the Consolidated Fund.

A new mint was erected on Tower Hill in 1810. In 1815 some alterations were made in its constitution; and in 1851 a complete change was introduced in the whole system of administration. The control of the mint was then vested in a master, a deputy-master, and a comptroller. The mastership, which had, in the early part of the 19th century, become a political appointment held by an adherent of the government, was restored to the position of a permanent office, the master being the ostensible executive head of the establishment. The operative department was entrusted to the assayer, the melter, and the refiner. The moneyers, who had from early times enjoyed extensive privileges and exemptions, and were contractors with the crown for the execution of the coinage, were abolished, and the contracts with the crown were entered into by the master of the mint, who also made subordinate contracts for the actual manufacture of the coin. Further changes were made in the administration of the mint in 1869. The mastership was added to the duties of the Chancellor of the Exchequer, without any addition of salary, and the offices of deputy-master and comptroller were amalgamated. A yearly saving of £10,000 is believed to have been effected by the changes of 1851, and a further £8000 by those of 1869, with an increase of efficiency. Mints were established at Sydney and Melbourne to coin the gold so largely found in Australia, in 1853 and 1869 respectively.

Processes of Coining.—Down to the middle of the 16th century little or no improvement seems to have been made in the art of coining from the time of its invention. The metal was simply hammered into slips, which were afterwards cut up into squares of one size, and then forged round. The required impression was given to these by placing them in turn between two dies, and striking them with a hammer. As it was not easy by this method to place the dies exactly above each other, or to apply proper force, coins so made were always faulty, and had the edges unfinished, which rendered them liable to be clipped. The first great step was the application of the screw, invented in 1553 by a French engraver of the name of Brucher. The plan was found expensive at first, and it was not till 1662 that it altogether superseded the hammer in the English mint. The chief steps in coining as now practised are as follows: The gold or silver to be coined is sent to the mint, for the most part in the form of ingots (Ger. eingiessen, Du. ingieten, 'to pour in,' 'to cast'), or castings; those of gold weighing either about 200 or 400 troy ounces, while the silver ingots are much larger. Before melting, each ingot is weighed and tested as to its purity by Assaying (q.v.). For melting the gold, pots or crucibles of plumbugo are used, made to contain each about 1200 ounces. The pots being heated in furnaces to a bright red heat, the charge of gold is introduced along with the amount of copper which calculation, based on the weight of the gold and its composition as ascertained by assay, proves to be necessary in order to bring it to the standard, which in Great Britain is 22 parts of pure gold to 2 of copper (see ALLOY). The metal, when melted, is poured into iron moulds, which form it into bars 21 inches long, $1\backslash frac\{1\}\{4\}$ inch broad, and three-eighths of an inch thick, if for sovereigns; and somewhat narrower, if for half-sovereigns. For melting silver (the alloy of which is adjusted to the standard of 222 parts of silver to 18 of copper) larger plumbago crucibles capable of containing 5500 ounces are used, and the metal is cast into bars similar to those of gold.

The copper, or rather bronze coinage, first issued in 1860, is formed of an alloy consisting of 95 parts of copper, 4 of tin, and 1 of zinc. The coins are only about half the weight of their old copper representatives. The processes of casting and coining the bronze are essentially the same as in the case of gold and silver.

The operation of rolling follows that of casting. It consists in repeatedly passing the bars between pairs of rollers with hardened steel surfaces, driven by steam-power; the rollers being brought closer and closer as the thickness becomes reduced. At a certain stage, as the bars become longer, they are cut into convenient lengths; and, to reduce the hardness induced by the pressure, they are annealed. The finishing rollers are so exquisitely adjusted that the fillets (as the thinned bars are called) do not vary in thickness in any part more than the ten-thousandth part of an inch. The fillets are still further adjusted in the British mint by means of what is called the 'draw-bench,' in which they are drawn between steel blocks, as in wire-drawing, and they are then exactly of the necessary thickness for the coin intended.

The fillets thus prepared are passed to the tryer, who, with a hand-punch, cuts a trial-blank from each, and weighs it in a balance, judging by experience whether the variation found to exist from the strict legal weight is such as to justify his passing the fillet into work.

The blanks of which the coins are to be made are cut out by means of punching-machines of simple construction, in which two or more short steel plungers are forced by an eccentric through the fillet, and enter holes in the bed of the machine; the fillet is then advanced automatically and the operation repeated. The scrap left after the blanks are cut out, called scissel, is sent back to be re-melted.

To ensure their being properly milled on the edge, the blanks are pressed edgeways in a machine between two grooves, one in a fixed steel block, and the other in the face of a revolving steel disc, whereby the edge is raised and the blanks are brought to a uniform diameter. After this they are annealed to soften them, before they can be struck with dies; they are also dipped into hot dilute sulphuric acid, to remove oxide of copper from the surface. Subsequently they are washed with water, and dried in hot sawdust.

We now come to the press-room, where the blanks receive the impression which makes them perfect coins. The screw coining-presses which were erected in the mint in 1810 were superseded in 1882 by lever presses of what is known as the Uhlhorn pattern. Of these no less than sixteen now exist in the mint. It is not necessary to give any detailed account of their mode of action, but it may be explained that the lower die (see DIE-SINKING) is fixed, and, after the blank has been automatically laid on it, a steel collar which is milled on the inside rises so as to surround this blank, and, while it is thus enclosed, the upper die descends upon it, considerable pressure being applied through a lever acting on a toggle joint. It will thus be seen that at the moment at which the pressure is applied the blank is completely enclosed, the result being that all the details which exist on the two dies and on the collar are reproduced in the comparatively soft metal of the blank. The upper die then immediately rises, the collar descends, and the now finished coin is automatically pushed on one side to give place to another blank. In cases where letters are put on the edge of a coin, a collar divided into segments working on centre pins is used. On the proper pressure being applied, the segments close round, and impress the letters on the edge of the coin. It is possible to strike coins at the rate of no less than 120 per minute, but it is found that the best results are obtained when the number does not exceed 90 per minute.

After being examined with a view to remove any faulty pieces, the finished coins are now passed on to be weighed in the automatic balances, since the act regulating the coinage (33 Vict. chap. 10) provides that no gold or silver coin shall be issued from the mint which varies by more than a specified and very small amount from the exact legal standard weight. These very beautiful instruments, which were introduced in 1844 by William Cotton, governor of the Bank of England, but have since been much modified and improved, are each capable of weighing about twenty-three coins per minute within $\backslash frac\{1\}\{1000\}$th of a grain, and distributing them into three separate compartments, respectively for those which are too heavy, too light, or within the limits of weight allowed by law. The first two classes are returned to be melted, while the third class, having been run on iron anvils with a view to eliminate such as are 'dumb,' are, so far as their manufacture is concerned, ready to be issued to the public. It is first necessary, however, that sample coins be taken for assay, as a final guarantee that they are within the limits as regards standard fineness allowed by the coinage act.

The gold coin is delivered to the importer (generally the Bank of England) as soon as finished, the weight of coin being the equivalent of that of the bullion imported, without making any deduction for loss in the operations of coinage or for the cost of alloying metal. Silver coin, however, is made up in bags of £100 nominal value, and stored in the mint until required by the Bank of England, Scotland, or Ireland for distribution in either of those countries, or by the government of a British colony in which imperial silver coin circulates. In the same way bronze coin is made up in bags of £5 nominal value and kept in store.

The following table gives the full legal weight in grains of all Imperial coins of gold, silver, and bronze:

It will be noticed that in the case of both gold and silver the values are in proportion to the weights of the coins, but that this is not the case as regards bronze: whereas a ton of pence is nominally worth £448, the same weight of halfpence or farthings is only valued at £373, 6s. 8d.

In the United States there are five mints—at Philadelphia (since 1793), New Orleans (1835), San Francisco (1854), Carson City, and Denver—all under the charge of the Bureau of the Mint of the U.S. Treasury Department, and presided over by the Director of the Mint. Only the first three are in active operation, the other two are really assay offices; and at Philadelphia alone all the authorised coins are struck. The United States coins and their weights are as follows, those marked with an asterisk having been discontinued:

The total amount of gold coinage minted from 1793 to the end of 1885 was 1,389,981,508.50; silver, 434,224,610.00; minor coin, $17,463,608.44.