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upon the surface of the water in the tanks containing the slime.

By allowing the slime when washed from the crusher to fall into tanks of sufficient capacity to retain one or two days' work, it will be found that this state of rest will facilitate the deposit of the particles of gold, and prevent much of the loss, which results from allowing the water to pass through the whole process, in one continuous stream, thereby carrying away much of the gold suspended in it before it has time to subside to the bottom of the current.

The fact is well known that gold leaf is easily wafted away by a very light current of air; if the gold can thus be suspended in so light a fluid as the atmosphere, it certainly can easily be washed away in a current of the more dense fluid, water, and more particularly, if that water should be rendered still less fluid, by the intermixture of large proportions of earthy materials. The tendency of gold, when in minute particles, to float upon the surface of water, may very easily be shown, by finely dividing a small portion of gold left upon a smooth card, and gently blowing the particles from the card upon the surface of water; or by filing a small quantity of gold over the surface of water; or by placing a small quantity of water in a basin, and so inclining it that only a portion of the bottom shall be covered by the water; then, allowing the filings to fall upon the uncovered portion, and so turning the basin that the water shall gently flow over that portion upon which the filings have fallen. These simple experiments will readily prove that gold will float away upon the water, unless the utmost care is used to prevent such an occurrence. By freely wetting the fingers, or, better still, a whis broom, and sprinkling the water drops off upon the water upon which the gold is floating, the advantage of this vertical. agitation of the water will be instantly apparent.

It is in this state of rest that the fine particles, mentioned by Hocheder, as quoted under the first rule, as "never to be gained by any means of separation founded on mechanical principles," are, most of them, at least, to be saved.

5th. In all horizontal rotary motion the discharge of slime should be from the centre.

When the slimes enter machinery of this character, their specific gravity causes them to fall at once to the bottom; there the centrifugal force of the rotary motion, either of the bowls themselves, or of the appliances contained in them, forces them to the circumference, and produces an under current in the same direction, and a tendency for the slime to accumulate near to the outer rim of the aparatus. The under-current is necessarily counterpoised by an upper current from the exterior to the centre. Nothing but the lightest particles can float along this gentle current across the apparatus, without sinking beneath the sur

face, before they pass the entire distance. Consequently only the lightest sands can pass away. By this plan little or no loss can ensue from the floured mercury, as it must sink and be recombined with the fluid metal.

6th. Fresh, clean water should be introduced at each stage of the amalgamation.

The object of this arrangement is so obvious that it requires but brief explanation. After each state of rest, the slime will have to be removed by hand from the tanks, and fed into the machinery; it here becomes necessary that the water should be as free as possible from any admixture of foreign matter, to allow the specific gravity of even the most minute particles of gold to have its full effect; which it could not do were the same water, as had already been once used, to be again operated with.

Considering the ores then as already at hand for operating upon, the first step in the process will be to reduce them to that state of division by which the gold can be most easily separated from the accompanying rock; this is accomplished by

CRUSHING.

The crushing of gold ores has been endeavored to be effected in as many various ways as there were minds to plan the mechanical arrangement. It has appeared as if every man that ever heard of a gold mine, immediately believed himself to be the only person capable of constructing the requisite machinery for the successful operation of the ore. Men have placed themselves before their tables, and spreading out their drawing instruments, have elaborated upon the smooth surface of the Bristol-board or their drawing-paper, most beautiful specimens of human ingenuity, developing in the ablest manner the highest perfection of mechanical principles, and producing ornamental delineations of gold-working appliances, which, when patented, constructed, purchased, transported and placed upon the mines, were found worthless, futile, and useless. They lost sight of the important fact, that some experience was a necessary ingredient. to combine with their calculations; they forgot the homely adage that "Necessity is the mother of invention," and consequently have produced works that are now scattered broadcast over the mining districts, which serve only as monuments of folly and illdirected labor. To crush gold ores, which usually are of siliceous formation, requires heavy, ponderous machinery, the mere weight of which, passing over the quartzose rock, reduces it to a powder. No elaborate combination is involved in this requirement. The machinery must be massive, simple, and of such construction, that the portions most liable to wear away by the friction of the ore, can be easily replaced; too strong in its parts to break under the powerful pressure to which it is subject, and made of such permanent material that no exposure to the changes of cli

mate or weather can sensibly affect it. It should be sufficiently capable to perform all the work that may be required of it to do; that is, if twenty, thirty, or even fifty tons of ore per each twenty-four hours, can be raised from a mine, the crusher should be able to fully pulverize it. The machinery should always be sufficient to control the mine. If not adequate for this purpose an accumulation of ore must ensue, or a retarding of the successful development must occur. It is owing to the failure of so many inefficient machines, that much of the doubt and discredit now attached to mining operations has arisen. It is seldom that an actual practical test has been made of the machines before they are offered for sale; the whole merit which they are said to possess is purely theoretical. The only way to prove any machine is not upon a ton or two of ore under the most favorable circumstances of working, but to place it upon the mine, and with the work before it, see if it can be made to execute it. No other test should ever be accepted. Too often the merits of the machines have been extolled with all the force that language and imagination could command; and could they have accomplished a moiety of the "immense advantages," which were claimed for each, as its own peculiar value, they would almost have gathered the golden grains from a barren sand, or have created them from the ingredients of a solid rock, utterly devoid of metallic presence. The uninitiated have credited these tales of marvel, and have eagerly paid their good dollars for bad stock. And now, without stopping to discriminate between their own folly connected with illegitimate mining, and sound common sense, and true economical mining, they class all mineral operations under the censorious title of "humbug!" From the feeling thus engendered and promulgated, capital which else would be invested in mining properties, seeks other channels, to the detriment of the true mining interest of the country. There is no branch of industry, from the advancement of which the capitalist can de: rive more pecuniary emoluments than from that of mining; legitimate, economical, well-directed mining. From the little knowledge which I have been able to gather of the mineral resources of our country, I can foresee that ere the close of the next half century, the mining interest of the United States is destined to be the most important resource of national wealth. It is therefore with emotions of pain that I see these worthless specimens of machinery palmed off upon a class of men, who, with a laudable ambition of availing themselves of mechanical aid in the prosecution of their labors, and by their very eagerness to progress, are easily deceived by the plausible and falsely termed merits of the invention. Every such machine that is placed upon a mining location is an additional clog and hinderance to the prosperity of that mine individually, and to the mineral welfare of the entire country. How, ask the mining managers, are we

to know whether a machine can be made to fulfil the promised results? We hear it strongly attested to, on the score of merit, and tied down as we are with our local duties, we cannot make the personal examinations we would desire to do, and must take the risk of relying upon the judgment of less practical friends." If the mining men would but adopt as an universal rule, that they would not purchase any machine until it had been placed upon their mine and proved by actual results to be all that its projectors had promised, they would escape the wasteful expenditure of thousands of dollars, that might better be devoted to sinking shafts, and to driving galleries upon the veins in their possession. Any company, or any individual, that entertains full confidence in their appliance, will not hesitate, upon a valid contract from the mine-holders, to purchase the machine if it will perform a stipulated amount of work, to place it upon the property, and give it a fair and impartial trial. If such a course should be adopted by any company, their own interest will prevent them from over-estimating the efficiency of their machine, as such exaggeration would render certain a failure of their contract; they would rather under-estimate its ability to work, that there might not ensue too great a risk of failure in performance.

Upon the property which has been under my management for the past year there is in use a crushing machine which was placed here under the above-named terms of contract, and which not only performs all that its proprietors claimed for it as able to do, but is capable of turning out at least twenty-five per cent. more work. It is a ponderous and simple machine, easily kept in running condition, and will readily crush from two to three tons of quartz per hour. We run it with an engine of about thirty horses' power, which also carries the amalgamating force of eight arrastres and thirty-four stirring bowls. I merely allude to the facts, and deem it but an act of simple justice to an ingenious inventor, to state, that "Bullock's Quartz Crusher" is the best adapted machine for reducing the quartzose ores to the required fineness in the shortest time of any mechanical appliance that has fallen under my observation.

It is my fondest hope and strongest desire to see the mineral value of our country correctly appreciated; and though but an humble laborer in the vast field, I am anxious to perform my portion of the great work that is to be accomplished.

The most common method of reducing the ores to a powdered state is by means of the

CHILIAN MILL.

It is constructed by having two large and heavy stone wheels made to revolve upon a solid stone bed. Around this bed a wood work of about twelve inches in height is placed, forming a large tub, of which the stone bed constitutes the bottom. Into VOL. VII.-2

this basin the ore is thrown by small portions from time to time, and is crushed by the weight of the wheels rolling over it. The stone bed is usually about six feet in diameter, and from ten to eighteen inches thick. The wheels, or "runners," as they are called, are of about the same dimensions, and are kept in motion by suitable geering connected to an upright shaft, which is "stepped" upon the centre of the bed, and makes from six to ten revolutions per minute. The axles upon which the runners revolve are placed within a strong framework, which surrounds instead of being attached to the shaft; thus allowing sufficient vertical play to the runners while passing over the fragments of ore. The average quantity of ore crushed by one of these mills in twenty-four hours, is about forty bushels, or two tons. A stream of water enters over the rim upon one side of the tub, and is discharged over the rim on the opposite side. This stream should be sufficient in quantity to hold the comminuted sands in suspension, and allow them to be floated off in a thin slime. If the quantity of water is insufficient the sands will pass away in so thick or muddy a condition that the specific gravity of the gold will be of no avail, and it will be carried off by mechanical suspension. If too heavy a head of water is applied the sands would be washed away, either in too coarse a state for the gold to be liberated, or too rapidly for it to be saved. A great advantage will be derived from the occasional addition of a small quantity of quicksilver to the sands in the mill. It will be found, if a fair trial is instituted, that more amalgam will be obtained from the same quantity of quicksilver applied at inter-· vals than would be gained by adding it at one time. A positive advantage will be obtained by having the Chilian Mill so constructed that its discharge shall be through the centre. In this mill particularly, a slow and uniform rate of operation must be maintained; the work cannot be hurried without entailing a loss of gold.

In Mexico and South America the Chilian Mill is used dry. In the United States it is always used with water.

It has been suggested that greatly increased beneficial results. will follow the occasional stoppage of the flow of water in the Chilian Mill operation, particularly while crushing a bed of ore. This point appears to me so feasible that I should consider it well worthy the attention of all interested.

I find that Mr. Boussingault tried at the Columbian Mines the same principle, but in the arrastre. "The mineral was put into the arrastre, with a sufficient quantity of water to give it the consistency of a thin paste, * and was then the amalgam was

ground for thirty-two hours,

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obtained with great facility." Marmato, August 12, 18It will be found advantageous to carry out the principle of rest, by having tanks, into which the Chilian Mill will discharge its sands or slime; it will be well to have three tanks so ar

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