These were succeeded by iron crucibles, especially for melting silver, and these have now been generally replaced by graphite (plumbago) crucibles made of a mixture of clay and graphite. Good graphite crucibles can be used many times in succession if they are heated gradually each time, but they are usually discarded after about fifteen or twenty meltings. At the Royal Mint gold is melted in crucibles about 10 in. in height and 8 in. in diameter at the widest part. The charge is from 1200 to 1300 oz. (37-3 to 40.5 kilograms) of metal. The furnace is 12 in. square and 2 ft. deep from the fire-bars to the cover. An old crucible is cut off about 2 in. from the bottom and the bottom piece is inverted and placed on the fire-bars as a support for the crucible. The "muffle," a graphite cylinder 6 in. in height, is placed on the crucible to allow room for long bars to be melted in the crucible and to prevent the surrounding

and C is the flue, common to two furnaces and leading to the stack. The handle D, acting through the gear wheels E, F, G and H, turns the cogwheel K, which moves the curved rack of the cradle and tips the crucible M. The molten metal is poured into the moulds N, which are carried on wheels running on rails Q. The parts of the range of moulds are brought tightly together and held in position by the bars O and the screw P, and when one mould is filled the carrier is moved forward on its rails by wheels worked by a handle also shown in the figure. In some other mints still larger crucibles are used, containing various amounts up to about 1000 kilograms or over 30,000 oz. In foreign mints the molten metal is generally transferred from the crucible to the moulds by dipping crucibles or iron ladles covered with clay. Gas is used as fuel for the melting furnaces at Philadelphia. It is cleaner than coke and is said to

coke from falling into it. The flue, of about 5 in. square, communicates with a stack 60 ft. high. In many mints the flues pass into condensing chambers where volatilized gold and silver are recovered. The crucible is at a red heat when the gold is charged in, the copper being added last, and a graphite lid put on the crucible to check loss by volatilization. The charge is completely melted in about half an hour, and it is then thoroughly mixed by stirring with a graphite rod. The crucible is then lifted out by circular tongs suspended in such a way that two men can take part in the operation. The contents are poured by hand into moulds which are contained side by side in an iron carriage running on wheels, fig. 1, OP. The molten gold, which is of a pale green colour, solidifies at once in the iron moulds, and the bars can be taken out immediately. Bars from which sovereigns are to be coined are 22 in. long, 1 in. wide and in. thick, and about seven such bars are cast from one pot. The rough edges of the bars are removed by a circular revolving file, and the hollow ends are cut off. Pieces are cut out for assay, and the bars are then ready for rolling. The amount of gold melted in an ordinary day's work is two tons to two and a half tons, of the value of £250,000 to £300,000. For silver larger crucibles are used, containing about 5000 oz. troy (155 kilograms). They are heated in circular furnaces 21 in. in diameter and lifted out with circular tongs suspended from a travelling crane which is worked by electricity. The crucible is placed in the pouring cradle, which has been in use since 1816, and is shown in fig. 1. Here A is the iron cover surrounding the furnaces, B is the revolving lid of a furnace, I

save time and to reduce the loss of the precious metals. At Denver and Ottawa the fuel used is "first distillate" oil, which is found to be cheaper than either naphtha or gas. The oil is pumped from buried tanks and warmed to about 90° F. before it reaches the burners at the furnaces. At the Denver mint the crucibles are used for from twelve to fifteen meltings with oil fuel, whereas they were soon destroyed when gas was employed. A charge of 6000 oz. of gold is melted in about an hour. The melting losses amount to about 0-2 per 1000 of gold and 0.6 per 1000 of silver in the Royal Mint. The losses are caused by volatilization, by the absorption of metal by the crucible, stirring rod, &c., and by occasional projection of particles from the pot into the furnace. The ash-pit is lined with iron plates to facilitate the recovery of metal accidentally spilt. All crucibles and other materials which might contain precious metal are ground up and washed in a pan, and the pannings together with a selection from the floor sweepings are remelted. The residues (the Mint "sweep ") are sold to refiners or ore-smelters. Rolling. The cast bars are reduced to the thickness of the coin by repeated passages between rolls. These are cylinders of cast iron or steel from 6 in. to 15 in. in diameter set parallel to one another with a small interval between, and revolved by electric or steam power. They are divided into breaking-down and finishing rolls, the latter being of smaller diameter than the former. The power is usually transmitted through toothed' wheels, each roll being driven independently in some cases, while sometimes power is ap plied to the lower roll only, the upper roll being coupled to it. The

power required for breaking down mint bars amounts to from 25 to 35 h.p. The bars are fed to the rolls by hand. Heavy pinches are applied at first, the space between the rolls being diminished by a hand-screw after each passage of the bars through them. When the bars are nearly to gauge, light pinches are given, the power required by finishing rolls being about 5 h.p. only. The reduction in thickness of the bars is accompanied by a slight increase in their width and a very great increase in their length, so that it is generally necessary to cut partly rolled bars into two parts to keep them of convenient dimensions. By repeated passages through the rolls the bars are hardened, and to facilitate further reduction they are usually softened by annealing before being passed to the finishing rolls. In some mints the fillets are annealed frequently, the fillets for one-mark pieces at the Berlin mint, for example, being annealed four times in the course of rolling. In this case the bars are reduced from 51 mm. in thickness to 1 mm. by being passed thirteen times through the rolls. At the Vienna mint the practice has been to anneal silver bars after cach passage through the rolls. On the other hand, in the United States mints, the use of very carefully refined metal has made it possible to discontinue the annealing of partly rolled bars. In the Royal Mint silver bars are annealed once during rolling by passing through a Bates & Peard gas furnace. The fillets are placed on an endless chain which moves slowly through the furnace, returning underneath. At each end of the furnace is a trough of water which covers the furnace mouth, so that air is prevented from entering the furnace. The chain dips below the water, then rises into the furnace and passes down into the other trough on its way out. The result is that so long as the fillets are hot they are kept from contact with the air and blackening of the metal is prevented. In some mints the drag-bench or draw-bench is used after the rolls to equalize the thickness of the fillets. The fillet is drawn between two little steel cylinders which do not revolve and are held rigidly in position. The principle resembles that used in wire drawing. It was introduced by Sir John Barton at the Royal Mint in 1816 and was abandoned there in 1905. The thickness of the

FIG. 2.-Gauge Plate.

fillets is measured by the gauge-plate shown in fig. 2. When they have been reduced to the correct thickness they are examined by the trycr," who cuts out one or two blanks from each fillet with a hand machine and weighs them on a delicate balance. If the weight of the blank is slightly below the standard weight, a somewhat larger cutter is used, so that the blanks may be of correct weight. If the blank is too heavy the fillet may of course be passed through the rolls again. Remedy-The degree of accuracy required is indicated by the "remedy allowance for weight, which is different for each coin, and is the maximum difference from the standard weight which is allowed by law. In the sovereign it is 0-2 grain or about 1-62 per 1000. As the mean thickness of a sovereign is 0.0466 in., the remedy for weight corresponds to a difference of less than rodo in. in the thickness of the fillet. The remedy for English silver coins varies from 2 grains or 4.58 per 1000 in the case of the crown, to 0-087 grain or 11.97 per 1000 in the case of the silver penny. The remedies for weight on foreign coins are in general greater than those allowed in the British Empire, averaging 2 per 1000 for gold coins. Reference may here be made to the similar working margin allowed in respect of the fineness of gold and silver. In England the remedy for fineness is 2 per 1000 on gold coins and 4 per 1000 on silver coins above and below the legal standard. Thus gold coins would be within the limits if they contained between 914.6 and 918.6 parts of gold per 1000. Remedies are intended to cover accidental variations from the exact standard and are now generally used only

in this way. In former times, however, advantage was sometimes taken of the remedy as a means of profit. In the reign of Queen Elizabeth, the master of the Mint, finding the allowance under his contract to be insufficient, availed himself of the remedy on the silver coinage, which amounted to 61d. on the pound troy, or about 8-7 per 1000.

Cutting Blanks.-The cutting machine used in the Mint is shown in fig. 3. The revolution of an eccentric A causes two short steel cylinders or cutters mounted on a block of iron B, suitably guided, to enter two holes in a plate fixed to the bed of the machine. When the fillet FF is brought above the holes, the cutters descend and force disks of metal through the holes. After each descent of the cutters, the fillet is advanced by small gripping rolls C C' C worked by a ratchet wheel E driven from the shaft which bears the eccentric A. The disks fall down the tube G to a receptacle on the floor. The cutters are so placed as to remove blanks in the manner shown in fig. 4, this arrangement leaving less "scissel or residual metal than any other. In the case of very large silver coins only one blank is cut in the width of the fillet, but bronze fillets are made wider so that three penny blanks are XVIII 10

cut out at each stroke of the machine. The cutting machines at the Mint work at 160 revolutions per minute, so that each of the eleven machines would be capable of cutting 19,200 blanks in an hour it could be fed continuously. The scissel, which amounts to about 30% of the metal operated on, is returned in bundles to the melting house. Marking. The blanks are then passed to an edge rolling machine, by which they are thickened at the edge so as to form a rim to protect the finished coin from wear. This operation is called marking, because originally the edges

FIG. 4.

FIG. 3.-Cutting Machine.

FIG. 5.

were not only thickened but were also marked with an inscription. This is still done in the case of many foreign coins. The letters are sometimes sunk and sometimes raised. Like the graining or milling on the edge of many coins, the inscriptions were intended to put a stop to the practice of clipping and filing coins, which was prevalent in the 16th and 17th centuries. They also render the manufacture of counterfeit coin more difficult. At the Royal Mint the blanks are passed between the parallel faces of a revolving steel plate and fixed block. The plate has a circular groove in its face and the block has a corresponding curved groove. The blank passes between these grooves. The distance between the block and the plate is adjusted so as to be slightly less than the diameter of the blank, and the result is that the edge of the reduced before it escapes from the blank is thickened and its diameter through this machine per minute. In machine. About 720 blanks are passed marking machines in some foreign mints the groove is in the periphery of the revolving wheel, and the grooved block is curved (fig. 5). Annealing and Blanching the Blanks.-The blanks are next being passed to the coining presses. softened by annealing, and are then thoroughly cleaned before blanks are protected from oxidation, and after their passage through In England gold and copper the furnace are merely washed in colanders with water and dried passed through rotary gas furnaces in which no attempt is made to with sawdust in a rotating drum. Silver blanks, however, are exclude the air. The blanks are charged into a hopper at one end of the furnace and conveyed towards the other end by a revolving The blanks fall through an aperture after having been heated for a few minutes. They are at a dull red heat by the formation on the surface of a film of oxide of copper. This and are allowed to cool gradually in the air and become blackened is removed by solution in hot dilute sulphuric acid and a layer of pure frosted silver is left on the surface, which appears dead white in colour, and has lost its metallic lustre. The operation is called England and is still employed in some mints. The removal of part "blanching." A similar method was formerly used for gold coins in of the copper from the blank raises the percentage of silver contained in them and this is allowed for by adding an equivalent amount of Copper to the metal when it is melted. The amount of copper removed from silver blanks containing 900 to 925 parts of silver per 1000 is from 0-6 to 1.0 per 1000. The process will probably be abandoned as soon as the tarnishing of the metal during rolling and annealing can be avoided.

Archimedean screw.

Coining Press.-The blanks are converted into coin by receiving an impression from engraved dies. Each blank is placed on the lower of two dies and the upper die is brought down forcibly upon it. The pressure causes the soft metal to flow like a viscous solid, but its lateral escape is prevented by a collar which surrounds the blank (milled"), or engraved with some device. In the last case the while it is being struck. The collar may be plain, or crenated collar must be made in two or more pieces, as otherwise the coin could not be removed without injury. The collar for striking English crown pieces is made in three sections now that raised lettering is put on the edge of the coin. Sunk letters, such as occur on the edges

562

MINT

at the Mint strike from 90 to 125 coins per minute, most of them and it is possible with these to strike between 700,000 and 800,000 pieces in an ordinary working day. working at the rate of 110 coins per minute. There are 19 presses

아

FIG. 7.

D

by ringing, and each coin is then weighed separately by being passed Weighing the Coins.-Gold and silver coins are examined and tested automatic balance for weighing single coins over delicate automatic balances. The first 1843, and was designed by William Cotton, was introduced at the Bank of England in the deputy governor of the Bank. In 1851 these balances, improved by Richard Pilcher, were introduced at the Royal Mint, and modifications of them are now used at most foreign mints. For mint use it is necessary that they shall distinguish between "light, "heavy" and "good" coins which do not differ from standard by more than the small weight known as the " The balances used in the Royal Mint were remedy" (see above). further improved by J. T. Butler in the year 1889. The balance consists essentially of a beam with two scale pans, one for the coin and the other for the counterpoise. The beam is released and in the course of a second or so takes up a certain position dependent on the relative weights of the coin and counterpoise. Its position is then fixed by an automatic grip, and the coin falling down a shoot enters one of three compartments of a box, according to the position of the beam when it is arrested. The chief working parts are shown in fig. 10. The beam A is of steel made in one piece,

A'

FIG. 9.

FIG. 8.

to the bed of the machine, and the blank is placed exactly upon it. The collar A' is then raised by the lever G so as to encircle the blank, and the upper die which is held at A is brought down. This is done by the little crank B on the axle of the fly-wheel, acting through the rod C, and the bent lever D, which forms a toggle-joint at E with the vertical piece of metal below it. The straightening of the togglejoint when C is pushed forward forces A down to strike the coin. The reverse movement of D lifts up the upper die and the collar drops simultaneously so that its upper surface is level with the face of the lower die on which the finished coin lies. Another blank moved on by the finger L pushes off the finished coin which falls down the tube N. The diagram, fig. 9, shows the relative position of the dies and levers more clearly. The dies and collar are shaded. The presses

FIG. 10

about 11 in. long. Its centre and end knife edges are shown in fig. 11. The scale pan for the coin is shown in fig. 12. B is the pan placed in a rouleau in the hopper C and the lowest one is pushed on to on which the coin rests, at a point above the beam. The coins are the pan B by a slide not shown in the figure. While the coin is being moved the hanger D is held firmly by the forceps E to prevent the pan from being pushed sideways. The forceps are then opened allowed to drop momentarily by a bent lever G acting on the pin G. until the ends of F press down on a stirrup in each hanger at H. H. and the beam released, but at this moment the levelling bar F is This brings the beam to a horizontal position. The lever G at once

lifts the bar F again by acting on the pin G' so that the bar F does not touch the stirrups at H and the beam and hangers are free to move. The coin is balanced by the brass counterpoise J on the lefthand hanger and by little weights made of wire attached to the right-hand hanger at K. If the coin is heavier than the lowest legal weight (that is, the standard weight less the remedy) the righthand side of the beam begins to fall and the left-hand one is raised. This movement proceeds until the stirrup L below the left-hand hanger is raised far enough to touch the rod M, which is equal in weight to twice the remedy. The movement is then stopped provided that the weight of the coin is not greater than the standard weight plus the remedy. If it is heavier than this, it raises the

FIG. 11.

FIG. 12.

weight M, and the movement of the beam and its hangers proceeds farther in the same direction. After about a second from the time of the final release of the beam, the forceps E again close and the hanger D is held firmly in its new position. The rod N is then lowered and allows the indicating finger O, which is pivoted at P, to fall until it rests on the stirrup R, which is part of the hanger D. The extension of O holds down the right-hand end of the rod S which is also pivoted at P, and enables its end to fit into one of the three inverted steps on the bottom of the shoot Q. The position of the shoot is thus determined. It stops over one of three orifices in the bottom plate of the balance. If the coin is light the rod S fits into the uppermost step and the shoot stops over the right-hand slot. If the coin is heavy, S fits into the lowest step and the shoot stops over the left-hand slot. The middle step and slot are for coins within the remedy. The movement of the slide now pushes another coin forward, and the weighed coin is displaced by it and falls down the shoot, through one of the slots. Each slot leads into a separate compartment and the coins are consequently sorted into three classes, light, correct weight and heavy. The balance turns to 0.01 grain. The driving power is applied by shafting through a number of cams. In the Royal Mint both light and heavy coins are returned to the melting pot. The proportion of rejected gold coin varies with the quality of the bullion, and frequently exceeds 10%. The percentage of rejected silver is often no more than 1%. In most foreign mints the blanks are weighed by the automatic balances before being struck, and those which are too heavy are reduced by filing or planing. A workman sitting at a balance files the edges of the piece and weighs it until it is within the remedy. The blank is then again passed through the automatic balance and is sent forward to the coining press if the correctness of the weight is confirmed. Since 1870 no adjusting of the weight of coins has been attempted at the Royal Mint. Heavy blanks have also been reduced chemically by making them part of the anode in a cyanide bath through which a current of electricity is passed. Some metal from the surface of each blank then passes into solution, and the blanks are reduced in weight with remarkable uniformity. This system was introduced into the Indian mints in 1873.

Telling The coin is counted and packed into bags for despatch from the Mint. The counting or telling is now carried out in the case of bronze and silver coins by ingenious machines introduced in 1891. The coins are spread on an inclined table by hand. They slide down the table and enter a narrow passage where only one can pass at a time, jamming being prevented by the joggling action of an eccentric rotating disk at the entrance to the passage. The coins are then gripped by a pair of india-rubber driving wheels, which force them past the rim of a thin disk with notches in its edge to fit the coins. As the disk is thus made to revolve, the coins are pushed forward, and falling down a shoot are received in a bag. The machine can be set to deliver a certain number of coins, after which the counting wheel stops automatically.

Trial of the Pyx.-Periodical examinations of the coins issued by the Mint have been made from very early times in England by persons appointed by the Crown. Specimens are selected from the finished coin and are put into a box or "pyx." At intervals these coins are weighed and assayed by a jury of skilled persons and the results reported to the Crown. A trial of the pyx is mentioned in the Lansdowne MSS. as having taken place in the reign of Henry II., but the practice had probably originated much earlier. The trial is now held annually by a jury consisting of freemen of the Company of Goldsmiths. Coins from the London and Australian mints are examined. The Company has been entrusted with the duty since the time of James I. Coins of foreign mints are generally submitted to examination by a committee of eminent chemists and metallurgists whose report is published in the official journals.

A full account of the work of the Mint, with valuable tables giving the amount of the coinage of gold and silver and bronze in the United Kingdom and the colonies in detail, and a résumé of the coinages of foreign countries, will be found in the Annual Reports of the Deputy Master and Comptroller of the Mint, which have been published since 1870. (T. K. R.)

MINTO, EARLS OF. The Scottish border family of Elliot which has held the earldom of Minto since 1813 has had many distinguished members. Sir Gilbert Elliot, bart. (1651-1718), and his son and successor, another Sir Gilbert Elliot (1693-1766), were both celebrated Scottish judges and both took the official title of Lord Minto. The elder Sir Gilbert was sentenced to death for his share in the rising of the earl of Argyll in 1685, but was afterwards pardoned; the younger Sir Gilbert was a scholar and an agriculturist. Among the children of the latter were John Elliot (d. 1808), a naval officer, who served as governor of Newfoundland and was made an admiral; Andrew Elliot, the last English governor of New York; and the poetess Jean, or Jane, Elliot (c. 1727-1805), who wrote the popular ballad "Flowers of the Forest." The eldest son, Sir Gilbert Elliot (1722-1777), who became the third baronet in April 1766, was a member of parliament from 1753 to 1777, and a friend and follower of the earl of Bute. He filled several public offices, and Horace Walpole said he was "one of the ablest members of the House of Commons." His second son was the diplomatist, Hugh Elliot (1752-1830), who represented his country at Munich, at Berlin, at Copenhagen and at Naples. He was governor of Madras from 1814 to 1820, and he died on the 10th of December 1830.

See the Memoirs of the Right Hon. Hugh Elliot, by the countess of Minto (Edinburgh, 1868).

The third baronet's eldest son was GILBERT ELLIOT, Ist earl of Minto (1751-1814). About 1763 Gilbert and his brother Hugh were sent to Paris, where their studies were supervised by David Hume and where they became intimate with Mirabeau. Having passed the winters of 1766 and 1767 at Edinburgh University, Gilbert entered Christ Church, Oxford, and on quitting the university he was called to the bar. In 1776 he entered parliament as an independent Whig. He became very friendly with Burke, whom he helped in the attack on Warren Hastings and Sir Elijah Impey, and on two occasions was an unsuccessful candidate for the office of speaker. In 1794 Elliot was appointed to govern Corsica, and in 1797 he assumed the additional names of Murray-Kynynmond and was created Baron Minto. From 1799 to 1801 he was envoy-extraordinary to Vienna, and having been for a few months president of the board of control he was appointed governorgeneral of India at the end of 1806. He governed with great success until 1813. He was then created Viscount Melgund and earl of Minto. He died at Stevenage on the 21st of June 1814 and was buried in Westminster Abbey.

The earl's second son was Admiral Sir George Elliot (17841863), who as a youth was present at the battles of Cape St Vincent and the Nile, and who was secretary to the admiralty from 1830 to 1834. A nephew of the earl was Sir Charles Elliot (1801-1875) also an admiral, who took a prominent part in the war with China in 1840. Afterwards he was governor of Bermuda, of Trinidad and of St Helena.

GILBERT ELLIOT-MURRAY-KYNYNMOND, 2nd earl of Minto (1782-1859), eldest son of the 1st earl, was ambassador to Berlin from 1832 to 1834, first lord of the admiralty from 1835 to 1841 and lord privy seal from 1846 to 1852. His influence in the Whig party was partly due to the fact that his daughter, Frances, was the wife of Lord John Russell.