ated by cutting out a part of the gold, and filling up the space by base metal; if it is in gold dust, it may be "doctored" by introducing a quantity of copper scales coated with gold; if it is in gold bars, a hole may have been drilled, the space filled up with other metal, the orifice being concealed by remelting; if it is of plate or jewelry, it is sure to be largely alloyed. Nuggets themselves are sometimes counterfeited; not long ago such a nugget, weighing 25 ounces, was brought to the office; on melting, it appeared that it contained no gold at all, but was made of a mixture of metals, galvanized with gold. Probably the rogue who deposited it pledged the certificate somewhere for a small part of its presumed value. In any event the Government lost nothing, for it promised to pay only the value of the gold and silver in the deposit, which happened to be nothing at all. Long practice has made the officers such judges of bullion that from appearance alone they could decide upon its value with great accuracy. But it is not worth while to do so. It is better to give a receipt for the gross weight, for the scientific tests through which each deposit must pass will detect the minutest portion of foreign substance. The bullion, having been weighed, is placed in copper-lined boxes, with a card stating the number of the deposit, the character-whether bars, grains, or coins-and the weight. The box is securely locked and the number chalked on the lid. This number accompanies it through all its preliminary operations. The boxes of bullion are put upon a railroad at the door of the Weigh-Room, and run across the courtyard to the rear building, and hoisted to the Deposit Melting Room. The visitor is at first surprised at the apparently careless manner in which the metal is treated. Lumps and bars, which he is told are gold, lie about on the floor, to be had for picking them up. But if dishonestly inclined, let him try to pocket a piece and he will learn his error. His surprise will soon be directed to the completeness of the method for saving every particle of gold. The floor is of concrete, covered with an iron grating which allows every particle of dust to sift through. This is cast in sections, so that it can be readily removed, the smooth concrete floor swept, and the sweepings collected. The working garments of the men, the towels, brushes, and brooms which are used, all become impregnated with gold. These are preserved, burned, ground to powder, and every particle of the gold contained in the dust is ultimately recovered. Arranged around this room, close to the wall, are ten iron furnaces for melting the gold. In these, buried in the red-hot coals, are large crucibles, made of clay and black-lead, which are the best materials for withstanding the intense heat to which they are subjected. In shape they resemble the earthen brown-bread pots of our New England mothers, having, however, a lip from which to pour the metal. The crucible being red-hot, a small handful of borax is thrown in, to cleanse the particles of gold and cause them to unite in one mass. It also lubricates the sides of the crucible, and prevents the metal from adhering, on the same principle that Mary Ann greases the griddle previous to frying the buckwheat cakes. Sometimes as much as eighteen hundred ounces of gold is placed in one crucible. They never mix two depos its, however, and if the deposit is only six ounces, it has a separate melt. When filled the crucible is covered and left for about forty min utes, the operator occasionally skimming the dross and dirt from the top. By this time it is thoroughly heated and mixed, which is important, as the portion taken from it to assay should be a fair representation of the whole. If it were not homogeneous, the assay would make the whole either more or less valuable than it really is. In front of each furnace is a little ledge, upon which any thing can be placed. The metal being in readiness, iron moulds are placed on these ledges. These are called "shoe-moulds," from some fancied resemblance to the sole of a shoe. Each of these is divided into three compartments by partitions not quite as high as the sides of the mould. When the mould is filled these partitions make the cast so thin in their places that it can be easily broken. When the metal has reached the right heat, the melter takes the crucible in a pair of tongs, lifts it from the fire, and pours its contents into these moulds. Remaining but a moment to cool in the mould the bar is taken by a man, with a pair of thickly stuffed canvas mittens, and tipped into an iron basin. The gold is still so soft that two bars touching will adhere. Here the deposit number which was given in the Weigh-Room is stamped on each division of the bar, so that in case it should be broken each part could be identified. After each melt the crucible is scraped out, and its OLD CRUCIBLES. MELTING-ROOM.-POURING OUT THE METAL. contents added to the mass to be afterward burned, and the ashes ground to powder, in order to extract the gold. This is called "Deposit melting," its object being to free the metal from impurities and render it homogeneous, so that an assay-slip cut from one of the bars will fairly represent the whole deposit. The fineness of the deposit will be determined by a very delicate analysis performed upon the assay-slip; and the elements required for calculating the value are the weight after melting and the fineness. We follow our deposit, now in the shape of solid bars, to the Bar Weigh-Room, under charge of the Treasurer's assistant weigh-clerk. Here it is weighed to ascertain the loss in melting. This is an important operation, for upon it all calculations as to the value of the metal are based. It is performed in the presence of Mr. Kent, the melter and refiner, and constitutes the official delivery of the bullion to him by the Treasurer, in whose custody it has heretofore been. To provide for the security of the treasure while in his charge, he is furnished with a large safety-vault, absolutely proof against fire and burglars. We have now the net weight of our deposit, as bullion, freed from dirt. But it is not pure gold. It contains a portion of "base metals," as iron, copper, and so forth, and also some silver. If the deposit had been of plate or jewelry, probably half would have been alloy; if of foreign coin, about one-tenth; as it is of California gold, it is probably about one-twentieth. Government undertakes to ascertain the precise amount air and become oxydized, while gold and silver are not affected. This operation is performed in a "Muffle Furnace," which contains an oven large enough to hold about a dozen small crucibles, called cupels. These are made of calcined bone-dust, and are about the size of a large pill-box, of gold and silver in our deposit and pay us with a shallow depression to hold the metal. their worth-the "base metals" being here held The cupels being heated red-hot, the little ball of no value. This is done by the delicate pro- is dropped into one of them. It melts immecess of "assaying," conducted under the super-diately, forming a bright globule, which boils intendence of Dr. Torrey, the chief Assayer. and spins around. The surface rapidly oxydizes, and the oxyd runs down the sides of the globule, and sinks into the pores of the cupel. sors. away, as it were, the oxyds of the other metals; and is added for this purpose. In about ten minutes the scum disappears and the little globule suddenly brightens up; the cupel is removed from the furnace, and the metal, forming a little button about the size of a buck-shot, is taken out. This contains only gold and sil Two small bits called "assay-slips," are cut from different parts of the bar of each deposit. These are taken to the laboratory of the Assay-Lead forms a very liquid oxyd, which washes er, where they are hammered and rolled into slips so thin that they can be easily cut by scisThese slips, marked so as to show to what deposit they belong, are given to an Assayer, who has before him, inclosed in a glass case, a pair of scales with weights so delicate that they will indicate the half-millionth part of an ounce; the smallest weight resembling a bit of horse-ver; all base metals having disappeared. hair, an eighth of an inch long. The operator euts from the slip a piece weighing exactly half a gramme (the gramme being a French weight equivalent to about the 30th part of an ounce); to this he adds a gramme of pure silver, and incloses them in a wrapper of lead foil, weighing about ten times, as much as both gold and silver. This is rolled into a little ball, and taken to an adjoining room, where it undergoes two operations, one of which removes the base metals, and the other separates the silver from the gold. The first of these operations is called "cupellation," and depends upon the principle that base metals, when melted and raised to a high temperature, combine with the oxygen of the This button is hammered and rolled out thin, and then formed into a coil about as large as a pencil; this is called a cornet, and is to be subjected to the second process, for separating the silver from the gold. This is based on the fact that nitric acid will dissolve silver, while it will not act upon gold. But the proportion of silver in ordinary bullion is so small that each particle is surrounded and protected by the gold. The silver was added by the Assayer in order to diffuse the gold, and enable the nitric acid to come at the silver. The cornet is put into a "mattrass," a vial with a broad base and long neck. Into this is poured about an ounce of diluted nitric acid, which is boiled by placing the vial in a bed of hot sand. Bright red fumes soon arise, showing that the action of the acid upon the silver has begun. In about ten minutes the acid is poured off, and a quantity of less dilution is poured in to dissolve out the last traces of the silver. The silver and nitric acid uniting have formed nitrate of silver; and the remainder of the cornet is pure gold. It is a fragile roll, looking very like the brown tinder left in burning writing paper. This is taken out, washed in distilled water, and melted in a crucible, when it at once resumes its metallic appearance. It is carefully weighed in the operator's delicate scales, the result showing the fineness of the bullion; or how large a portion of it was gold, and how large alloy. The value of an ounce of any fineness being already known, the whole value of the gold in our deposit is readily ascertained. There was, moreover, some silver contained in our deposit-a small proportion probably, but still of some value-and for this we are to be paid. To ascertain this another half gramme is cut from the assay-slip, but no silver is added to it. It is cupelled to extract the base metals, and being weighed with the cornet of pure gold, the excess in weight shows how much silver there was. We have spoken of only a single assay; but in fact two are taken from each deposit, by different assistant-assayers. If these agree, they are deemed to be correct. If they differ, a new assay is made by each. If they still differ, it indicates that, in melting, the deposit was not thoroughly mixed, and that one portion of the bar was richer than another. In that case it is re-melted, and the process is gone over again. The process of assaying is a very delicate one, demanding great practical skill, since an error of the hundred-thousandth part of an ounce in the small piece assayed would make a sensible difference when multiplied by the quantity of a large deposit. But such is the acknowledged skill of our assayers, that Dr. Torrey's mark on a bar is never questioned. To indicate the fineness of gold, we adopt the simple French decimal system. The bullion is supposed to be divided into 1000 parts. If it is pure gold, its fineness is 1888; that is, 1. If it contains 100 parts alloy, its fineness is 200; or, in decimals, 900, and so on. The English ASSAY WEIGH-ROOM. mint has used a less scientific system. It supposes the bullion to be divided into 24 parts, called carats. If it is pure, it is said to be 24 carats fine. If it contains 2 parts out of 24 of alloy, it is 22 carats fine; and so on. Recently, however, the assayers have been required to make their reports also in decimals; and this system will probably in time wholly supersede the old one. I The Assayer fills out a report stating the fineness of the gold, and the amount of silver contained in it. This is sent to the office of the Treasurer, where the necessary calculations are made, and a memorandum is sent to the office of the Superintendent for verification. This memorandum is made out in tabular form, printed in crimson, and signed by the Chief Clerk, in behalf of the Treasurer. The memorandum for our deposit reads as follows: No. 1912.-Memorandum of GOLD BULLION deposited in the UNITED STATES ASSAY OFFICE, at New York, the 11th day of June, 1861, by John Smith. DESCRIPTION, California Grain.-WEIGHT, before melting, 1120-97 ounces; after melting, 1120-34 ounces.-Fineness, 923.-VALUE of the Gold, $21,376 20.-VALUE OF SILVER parted from the Gold, $94 40.-DEDUCTIONS for Parting, Coinage, and Fine Bars, $162 90.-NET VALUE $21,307 70. certify that the net amount of the above deposit is Twenty-one thousand three hundred and sevenDollars, payable at the U. S. Assay In Gold Coins, Office, only on presentation of the 821,213 30. Receipt, of a corresponding date and number, heretofore issued. viz.: In Silver Coins, 894 40. Our deposit, being of California gold, was quite pure. It lost less than half an ounce in melting, and being 923 fine, contained only 77 parts in a thousand of alloy, including the silver. It was, in fact, worth more than its weight in gold coin, of which our standard is 900; that of British coin being 22 carats, equal to about 916. If our deposit had been in foreign coin, with no counterfeits in it, about one-tenth part would have been alloy; if it had been jewelry or plate, probably it would have contained quite half alloy. As we chose to take our pay in coin, the cost of coinage is charged to us. The deduction would have been less if we had taken fine bars, as is usually done when the gold is wanted for exportation or deposit. The charges are made according to a fixed scale; varying for parting and refining with the character of the deposit; for fine bars it is 6 cents, and for coinage 50 cents, per hundred dollars. In four or five days after making our deposit it is assayed, its value ascertained, and we get our warrant for the payment in coin, for which, however, we must now wait a while. Formerly, when Uncle Sam was "flush," he used to keep a balance of a few millions in the hands of the Treasurer of the In MELTER AND REFINER'S VAULT. Assay Office, so that he could cash the Superin- | thirty days. But the hardship is not very great, tendent's warrants at once. But having met as we can easily "make a raise," if need be, on with some losses of late, and being subject to our warrant. heavy expenses, he finds this inconvenient. fact, he is "short." So we must wait for our money until the bullion can be sent to Philadelphia and coined. This will take twenty or GRANULATING. Hitherto our deposit has been kept separate from all others. But now that its value has been ascertained, and we have a warrant for the payment, it is considered as the property of the United States; and in the processes of refining is mingled with other deposits, losing its personal identity. The operation of refining, which Mr. Kent now commences, is a repetition on a large scale of the delicate processes of assaying. The bars are melted in a large crucible, twice their weight in silver being added. The molten mass is dipped up, and flung, with a peculiar jerk, into a cistern of cold water. We have all, for one purpose or another, poured melted lead into water, and noticed the minute fragments into which the metal is divided. The same thing happens to the compound of gold and silver. It is divided into small portions, and looks not unlike a heap of shavings. This process is called "granulating," its object |