Part 4

The silver in the condition in which it is received from the hands of the depositor, and generally filled with foreign impurities, is melted and then granulated, after which the whole mass is dissolved with nitric acid. The acid dissolves the base metals as well as the silver. The liquid metals are then run into tubs prepared for it, and precipitated, or rendered into a partially hard state, by being mixed with common salt water. After being precipitated it is called “chloride,” and resembles very closely new slacked lime. By putting spelter or zinc on the precipitated chloride, it becomes metallic silver, and only needs washing and melting to make the purest virgin metal. The base metals remain in a liquid state, and being of little value are generally thrown away. The process of refining silver is of two kinds; that of melting it with saltpetre, etc., which was known some thousands of years since, and the modern process of dissolving it in nitric acid, like the method of extracting it from gold in the above described operation.

After the separating process has been completed, the gold or silver is conveyed to the Drying Cellar, where it is put under pressure of some eighty tons, and all the water pressed out. It is then dried with heat, and afterwards conveyed in large cakes to the furnaces.

THE MELTING ROOMS

are on the first floor, in the west side of the building. Here all the metal used in coining is alloyed, melted and poured into narrow moulds. These castings are called ingots; they are about twelve inches long, a half-inch thick, and vary from one to two a half-inches in breadth, according to the coin for which they are used, one end being wedge-shaped to allow its being passed through the rollers. The value of gold ingots is from $600 to $1,400; those of silver, about $60. The fine gold and silver bars used in the arts and for commercial purposes, are also cast in this department.

[Illustration: CASTING INGOTS.]

[Illustration: INGOTS.]

These are stamped with their weight and value in the deposit room. The floors that cover the melting rooms are made of iron in honey-comb pattern, divided into small sections, so that they can be readily taken up to save the dust; their roughness acting as a scraper, preventing any metallic particles from clinging to the soles of the shoes of those who pass through the department, the sweepings of which, and including the entire building, averages $23,000 per annum, for the last five years.

The copper and nickel melting rooms, wherein all the base metals used are melted and mixed, is on the same side and adjoining to the gold and silver department. Up to the year 1856, the base coin of the United States was exclusively copper. In this year the coinage of what was called the nickel cents was commenced. These pieces, although called nickel, were composed of one-eighth nickel; the balance was copper.

The composition of the five and three cent pieces is one-fourth nickel; the balance copper. The bronze pieces were changed in 1859, and are a mixture of copper, zinc and tin, about equal parts of each of the two last; the former contributing about 95 per cent. There are seven furnaces in this room, each capable of melting five hundred pounds of metal per day. When the metal is heated and sufficiently mixed, it is poured into iron moulds, and when cool, and the rough ends clipped off, is ready to be conveyed to the rolling room.

THE ROLLING ROOM.

From the melting rooms through the corridor we reach the rolling room. The upright engine, on the right, of one hundred and sixty horse power, supplies the motive force to the rolling machines, four in number. Those on the left, are massive and substantial in their frame-work, with rollers of steel, polished by service in reducing the ingots to planchets for coining. The first process or rolling is termed breaking down; after that it requires to be passed through the machine until it is reduced to the required thinness—ten times if gold, eight if silver, being annealed in the intervals to prevent breaking. The rollers are adjustable and the space between them can be increased or diminished at pleasure, by the operator. About two hundred ingots are run through per hour on each pair of rollers.

The pressure applied is so intense that half a day’s rolling heats, not only the strips and rollers, but even the huge iron stanchions, weighing several tons, so hot that you can hardly hold your hand on them.

When the rolling is completed the strip is about six feet long, or six times as long as the ingot.

It is impossible to roll perfectly true. At times there will be a lump of hard gold, which will not be quite so much compressed as the rest. If the planchets were cut from this place, it would be heavier and more valuable than one cut from a thinner portion of the strip. It is, therefore, necessary to “draw” the strips, after being softened by annealing.

[Illustration: ROLLING MACHINE.]

ANNEALING FURNACES.

These are in the same room, to the right facing the rollers. The gold and strips are placed in copper canisters, and then placed in the furnaces and heated to a red heat; silver strips being laid loosely in the furnace. When they become soft and pliable, they are taken out and allowed to cool slowly.

THE DRAWING BENCHES.

These machines resemble long tables, with a bench on either side, at one end of which is an iron box secured to the table. In this are fastened two perpendicular steel cylinders, firmly supported in a bed, to prevent their bending or turning around, and presenting but a small portion of their circumference to the strip. These are exactly at the same distance apart that the thickness of the strip is required to be. One end of the strip is somewhat thinner than the rest, to allow it to pass easily between the cylinders. When through, this end is put between the jaws of a powerful pair of tongs, or pincers, fastened to a little carriage running on the table. The carriage to the further bench is up close to the cylinders, ready to receive a strip, which is inserted edgewise. When the end is between the pincers, the operator touches a foot pedal which closes the pincers firmly on the strip, and pressing another pedal, forces down a strong hook at the left end of the carriage, which catches in a link of the moving chain. This draws the carriage away from the cylinders, and the strip being connected with it has to follow. It is drawn between the cylinders, which operating on the thick part of the strip with greater power than upon the thin, reduces the whole to an equal thickness. When the strip is through, the strain on the tongs instantly ceases, which allows a spring to open them and drop the strip. At the same time another spring raises the hook and disengages the carriage from the chain. A cord fastened to the carriage runs back over the wheel near the head of the table, and then up to a couple of combination weights on the wall beyond, which draw the carriage back to the starting place, ready for another strip.

[Illustration: DRAWING BENCH.]

THE CUTTING MACHINES.

After being thoroughly washed, the strips are consigned to the cutting machines. These are in the rear of the rolling mills, and are several in number, each when in active operation cutting two hundred and twenty-five planchets per minute. The press now used, consists of a vertical steel punch, which works in a round hole or matrix, cut in a solid steel plate. The action of the punch is obtained by an eccentric wheel. For instance, in an ordinary carriage wheel, the axis is in the centre, and the wheel revolves evenly around it. But if the axis is placed, say four inches from the centre, then it would revolve with a kind of hobble. From this peculiar motion its name is derived. Suppose the tire of the wheel is arranged, not to revolve with, but to slip easily around the wheel, and a rod is fastened to one side of the tire which prevents its turning. Now as the wheel revolves and brings the _long side nearest the rod_, it will push forward the rod, and when the long side of the wheel is _away from the rod_, it draws the rod with it.

[Illustration: CUTTING MACHINE.]

[Illustration: STRIP FROM WHICH PLANCHETS ARE CUT.]

The upper shaft, on which are seen the three large wheels, has also fastened to it, over each press, an eccentric wheel. In the first illustration will be seen three upright rods running from near the table to the top. The middle one is connected with a tire around the eccentric wheel, and rises and falls with each revolution. The eccentric power gives great rapidity of motion with but little jerking.

The operator places one end of a strip of metal in the immense jaws of the press, and cuts out a couple of planchets, which are a fraction larger than the coin to be struck. As the strips are of uniform thickness, if these two are of the right weight, all cut from that strip will be the same. They are therefore weighed accurately. If right, or a little heavy, they are allowed to pass, as the extra weight can be filed off. If too light, the whole strip has to be re-melted. As fast as cut the planchets fall into a box below, and the perforated strips are folded into convenient lengths to be re-melted. From a strip worth say eleven hundred dollars, eight hundred dollars of planchets will be cut.

ADJUSTING ROOM.

[Illustration: DELICATE SCALES.]

The planchets are then removed to the adjusting room, where they are adjusted. This work is performed by ladies. After inspection they are weighed on very accurate scales. If a planchet is too heavy, but near the weight, it is filed off at the edges; if too heavy for filing, it is thrown aside with the light ones, to be re-melted. To adjust coin so accurately requires great delicacy and skill, as a too free use of the file would make it too light. Yet by long practice, so accustomed do the operators become, that they work with apparent unconcern, scarce glancing at either planchets or scales, and guided as it were by unerring touch.

The exceedingly delicate scales were made under the direction of Mr. Peale, who greatly improved on the old ones in use. So precise and sensitive are they that the slightest breath of air affects their accuracy, rendering it necessary to exclude every draft from the room.

PROGRESS IN COINING.

The methods of coining money have varied with the progress in mechanic arts, and are but indefinitely traced from the beginning; the primitive mode, being by the casting of the piece in sand, the impression being made with a hammer and punch. In the middle ages the metal was hammered into sheets of the required thickness, cut with shears into shape, and then stamped by hand with the design. The mill and screw, by which greater increase in power, with finer finish was gained, dates back to the Sixteenth Century. This process, with various modifications and improvements, continued in use in the Philadelphia Mint until 1836.

[Illustration: ANCIENT COINING PRESS.]

The first steam coining press was invented by M. Thonnelier, of France, in 1833, and was first used in the United States Mint in 1836. It was remodeled and rebuilt in 1858, but in 1874 was superseded by the one now in operation, the very perfection of mechanism, in which the vibration and unsteady bearing of the former press were entirely obviated, and precision attained by the solid stroke with a saving of over seventy-five per cent. in the wearing and breaking of the dies.

[Illustration: STEAM COINING PRESS.]

DIES.

[Illustration: DIES.]

The dies for coining are prepared by engravers, especially employed at the Mint for that purpose. The process of engraving them consists in cutting the devices and legends in soft steel, those parts being depressed which, in the coin, appear in relief. This, having been finished and hardened, constitutes an “_original die_,” which, being the result of a tedious and difficult task, is deemed too precious to be directly employed in striking coins; but it is used for multiplying dies. It is first used to impress another piece of soft steel, which then presents the appearance of a coin, and is called a _hub_. This hub, being hardened, is used to impress other pieces of steel in like manner which, being like the original die, are hardened and used for striking the coins. A pair of these will, on an average, perform two weeks’ work.

TRANSFER LATHE.

[Illustration]

The transfer lathe, a very complicated piece of machinery, is used in making dies, for coins and medals. By it, from a large cast, the design can be transferred and engraved in smaller size, in perfect proportion to the original.

THE COINING AND MILLING ROOMS.

This department, the most interesting to the general visitor, occupies the larger portion of the first floor on the east side of the building. The rooms are divided by an iron railing, which separates the visitors, on either side, from the machinery, etc., but allows everything to be seen.

[Illustration: MILLING MACHINE.]

The planchets, after being adjusted, are received here, and, in order to protect the surface of the coin, are passed through the milling-machine. The planchets are fed to this machine through an upright tube, and, as they descend from the lower aperture, they are caught upon the edge of a revolving wheel and carried about a quarter of a revolution, during which the edge is compressed and forced up—the space between the wheel and the rim being a little less than the diameter of the planchet. This apparatus moves so nimbly that five hundred and sixty half-dimes can be milled in a minute; but, for large pieces, the average is about one hundred and twenty. In this room are the milling machines, and the massive, but delicate, coining presses, ten in number. Each of these is capable of coining from eighty to one hundred pieces a minute. Only the largest are used in making coins of large denominations.

[Illustration: PERFECTED COINING PRESS.]

[Illustration: COINING PRESS.]

The arch is a solid piece of cast iron, weighing several tons, and unites with its beauty great strength. The table is also of iron, brightly polished and very heavy. In the interior of the arch is a nearly round plate of brass, called a triangle. It is fastened to a lever above by two steel bands, termed stirrups, one of which can be seen to the right of the arch. The stout arm above it, looking so dark in the picture, is also connected with the triangle by a ball-and-socket joint, and it is this arm which forces down the triangle. The arm is connected with the end of the lever above by a joint somewhat like that of the knee. One end of the lever can be seen reaching behind the arch to a crank near the large fly-wheel. When the triangle is _raised_, the arm and near end of the lever extends outward. When the crank lifts the further end of the lever it draws in the knee and forces down the arm until it is perfectly straight. By that time the crank has revolved and is lowering the lever, which forces out the knee again and raises the arm. As the triangle is fastened to the arm it has to follow all its movements.

Under the triangle, buried in the lower part of the arch, is a steel cup, or, technically, a “die stake.” Into this is fastened the reverse die. The die stake is arranged to rise one-eighth of an inch; when down it rests firmly on the solid foundation of the arch. Over the die stake is a steel collar or plate, in which is a hole large enough to allow a planchet to drop upon the die. In the triangle above, the obverse die is fastened, which moves with the triangle; when the knee is straightened the die fits into the collar and presses down upon the reverse die.

Just in front of the triangle will be seen an upright tube made of brass, and of the size to hold the planchets to be coined. These are placed in this tube. As they reach the bottom they are seized singly by a pair of steel feeders, in motion as similar to that of the finger and thumb as is possible in machinery, and carried over the collar and deposited between the dies, and, while the fingers are expanding and returning for another planchet, the dies close on the one within the collar, and by a rotary motion are made to impress it silently but powerfully. The fingers, as they again close upon a planchet at the mouth of the tube, also seize the coin, and, while conveying a second planchet on to the die, carry the coin off, dropping it into a box provided for that purpose, and the operation is continued _ad infinitum_. These presses are attended by ladies, and do their work in a perfect manner. The engine that drives the machinery is of one hundred and sixty horse-power.

After being stamped the coins are taken to the Coiner’s room, and placed on a long table—the double eagles in piles of ten each. It will be remembered that, in the Adjusting Room, a difference of one-half a grain was made in the weight of some of the double eagles. The light and heavy ones are kept separate in coining, and when delivered to the treasurer, they are mixed together in such proportions as to give him full weight in every delivery. By law the deviation from the standard weight, in delivering to him, must not exceed three pennyweights in one thousand double eagles. The gold coins—as small as quarter eagles being counted and weighed to verify the count—are put up in bags of $5,000 each. The three-dollar pieces are put up in bags of $3,000, and one-dollar pieces in $1,000 bags. The silver pieces, and sometimes small gold, are counted on a very ingenious contrivance called a “counting-board.”

[Illustration: COUNTING BOARD.]

By this process twenty-five dollars in five-cent pieces can be counted in less than a minute. The “boards” are a simple flat surface of wood, with copper partitions, the height and size of the coin to be counted, rising from the surface at regular intervals, and running parallel with each other from top to bottom. They somewhat resemble a common household “washing board,” with the grooves running parallel with the sides but much larger. The boards are worked by hand, over a box, and as the pieces are counted they slide into a drawer prepared to receive them. They are then put into bags and are ready for shipment.[8]

THE CABINET.

The room in the Mint used for the Cabinet is on the second floor. It was formerly a suite of three apartments connected by folding-doors, but the doors have been removed, and it is now a pleasant saloon fifty-four feet long by sixteen wide. The eastern and western sections are of the same proportions, each with a broad window. The central section is lighted from the dome, which is supported by four columns. There is an open space immediately under the dome, to give light to the hall below, which is the main entrance to the Mint. Around this space is a railing and a circular case for coins. The Cabinet of Coins was established in 1838, by Dr. R. M. Patterson, then Director of the Mint. Anticipating such a demand, reserves had been made for many years by Adam Eckfeldt,[9] the Coiner, of the “master coins” of the Mint; a term used to signify first pieces from new dies, bearing a high polish and struck with extra care. These are now more commonly called “proof pieces.” With this nucleus, and a few other valuable pieces from Mr. Eckfeldt, the business was committed to the Assay Department, and especially to Mr. Du Bois, Assistant Assayer. The collection grew, year by year, by making exchanges to supply deficiencies, by purchases, by adding our own coin, and by saving foreign coins from the melting-pot—a large part in this way, at a cost of not more than their bullion value, though demanding great care, appreciation, and study. Valuable donations were also made by travelers, consuls, and missionaries. In 1839, Congress appropriated the sum of $1,000 for the purchase of “specimens of ores and coins to be preserved at the Mint.” Annually, since, the sum of $300 has been appropriated by the Government for this object. More has not been asked or desired, for the officers of the Mint have not sought to vie with the long established collections of the national cabinets of the old world, or even to equal the extravagance of some private numismatists; but they have admirably succeeded in their purpose to secure such coins as would interest all, from the schoolboy to the most enthusiastic archæologist. The economic principle upon which the collection has been gathered is a lesson to all governmental departments in frugality, as well as a restraint upon the natural tendency to extravagance which has heretofore distinguished those who have a passion for old coins. There are thousands of coin collectors in the United States, and fortunes have been accumulated in this strange way. More than one authenticated instance has been known in this country where a man has lived in penury, and died from want, yet possessed of affluence in time-defaced coins.

RELICS.

Having referred to the portraits of the Directors of the Mint, we will cite other interesting subjects of observation, before describing the coins.

The first object in the Cabinet attracting attention is a framed copy of the law of Congress establishing the Mint, with its quaint phraseology with the signature of Thomas Jefferson. (See fac simile on page 11.)

In the first section, near the western window, is the assorting machine, the invention of a Frenchman, Baron Seguier, and which is now in use in the Mint at Paris.

The planchets for coinage are liable to be a little too heavy or too light; it is therefore necessary, at least in the case of gold, to assort them by weighing. This machine is designed to enable one person to do the work of many. “The planchets are thrown into the hopper at the rear, and, being arranged by the action of the wheel, slide down balances. By machinery beneath they are carried one by one to the nearest platforms to be weighed. If too heavy, the tall needle of the beam leans to the right and lifts a pallet-wire, which connects with an apparatus under the table by which the planchet is pushed off and slides into one of the brass pans in front. If the piece be light, the needle is drawn over to the left, and touches the other pallet, which makes a passage to another brass pan. If the piece be of true weight, or near enough, the needle stands perpendicular between the pallets, and the piece finds its way into the third brass pan.”