every one who has employed alternately a small light hammer, and a heavy one for breaking quartz before a battery. The inventor claims a decided advantage in his 400 light blows per minute over the 50 to 60 blows per minute delivered by the usual 600-pound stamp. A 5-stamp battery of this construction strikes 2,000 blows per minute; and while the first cost is greatly reduced in attaining the same crushing capacity, the power required to run it is also much reduced. The difference in freight to many places would also be very great. The machine is made of different sizes, and calculated to crush from 7 to 35 tons per twentyfour hours, according to size.

Whatever may be the results of its practical working on a large scale, there can be no doubt that it will prove an invaluable invention on account of its lightness, portability, and low price, to those who are engaged in the experimental development of quartz claims in localities where custom mills do not exist.

The capacity of the most powerful mills in California for crushing quartz is from ore to one and three-quarter tons per day (24 hours) to each stamp-the usual weight of stamp being from 600 to 700 pounds, and the drops 60 to 90 per minute. While this method is acknowledged to be slow, it is not probable that it will be superseded for many years, if at all; but in the mean time attention is being attracted to all inventions which claim to work greater amounts of quartz in a given time and at less expense for cost of machinery. Of this character is an invention of Mr. T. R. Wilson, known as "Wilson's Steam Stamp." The principle on which this mill operates is that of the direct application of steam to the stamp, the stem acting as a piston. The best results have been obtained with 70 pounds of steam and 206 drops per minute for each stamp. The average amount of ore which it is claimed can be crushed in a day (of 24 hours) is 23 tons with a No. 6 slot screen, and the average consumption of fuel is about one cord of wood to 10 tons of As instances of its capacity we are informed that some time since 10 tons and 800 pounds of rock were crushed in eight hours and forty-five minutes, using only one cord of oak wood. Again, in one run 51 tons were crushed in forty-seven hours, and 10,800 pounds in four hours fifty minutes with 68 pounds of steam. Several of Mr. Wilson's batteries are now in operation in San Diego County where they seem to meet with favor. A detailed description of this invention was given in the Mining Commissioner's Report for 1870, page 668, and it is briefly referred to here as one of the improvements apparently coming into more general use.

ore.

Not a year passes without the invention and introduction of numerous devices for the saving of fine gold and quicksilver in the tailings of our quartz-mills. These rarely achieve any reputation outside of the district in which they are invented, and many, after months of experi ment and trial, are rejected as useless. One of these undercurrent sluices, invented by Mr. Evans, and lately improved by Dr. Frey of Sacramento, is made of cast iron, with transverse corrugations on the bottom, semicircular in shape, and three inches deep. At the bottom of each alternate corrugation is a narrow slit through which the heavier material falls down into another riffle below with larger corrugations. Both riffles are set on the same grade, which should be about one foot in twelve. The lower box is charged with quicksilver. These sluices do not cake, nor do they require any attention beyond cleaning up once a week. They have stood the test of use in quartz-mills below all the contrivances for saving gold, and have made large returns of gold, H. Ex. 211- -3

silver, concentrated sulphurets, and quicksilver, that would otherwise have been lost.

The following is an assay of tailings saved at the Rhode Island Mills, Nevada, by these sluices during a run of one week:

Gold, $75.24; silver, $76.96; quicksilver, 250 pounds to the ton. One of the most important appliances in the economical running of quartz-mills is Stanford's Self-Feeding Apparatus, which is rapidly gaining favor with miners and millmen. This consists of a hoppershaped box placed above and in front of each battery. The feed-shovel at the bottom of the box is connected with a lever and a rod, and is shaken at each blow of the middle stamp of the battery by means of an upper tappet which strikes upon one arm of the lever. By this means motion is communicated to the forward end of the feed-box. One man can attend to twenty stamps, and the feeding is more regular than by hand, and materially increases the crushing capacity of the mill.*

Cement and gravel mining by machinery.-The process of treating hard cement and gravel by grinding and friction, instead of crushing under stamps, was introduced several years since by Captain J. B. Cox, who invented for this purpose the machine known as the "Cox Pan." This invention was intended to supersede the use of stamp-mills, by which method the bowlders, rarely containing gold, were necessarily crushed under the stamps at a great waste of time and power. This invention was not for a time received with favor, and in some cases was rejected after trial; but recent practical workings with the machine, since some improvements have been made, and after some changes in the manner of feeding, have demonstrated its utility and economy in the working of hard-cemented gravel. This pan is about five feet in diameter and two feet in height, and is intended to hold a charge of half a ton, or from 1,000 to 1,200 pounds. The rim of the pan is made of boiler-iron, and it has a perforated cast-iron bottom, through which the finer sand and auriferous material fall into the sluice-boxes or other gold saving appliances. The bowlders and large pebbles, which constitute so large a pro

*On the other hand, some of the most experienced millmen in California prefer feeding the batteries by hand to any form of automatic apparatus. The self-feeders, they say, may be superior to careless or unfaithful workmen; but a skillful feeder can, if he chooses, by giving to each stamp at exactly the right instant exactly the amount of rock it requires, increase the capacity of the battery to an extent which more than compensates for the extra outlay in wages.-R. W. R.

portion of the cemented gravel, are discharged at intervals through a section of the bottom of the pan, which is opened like a trap-door, by means of a lever, when they have accumulated to such an extent as to retard the grinding and pulverizing of the cement in the pan. Four revolvingarms are attached to a shaft which passes perpendicularly through the center of the pan. On these arms are fastened the steel teeth (in appearance like plowshares) which, in the rapid revolution of the arms, break up the cemented gravel. An abundant supply of water is distributed while the pan is in motion, and materially aids in the disintegration of the gravel. Better results are claimed when the pan is fed continuously instead of by charges, which was the practice on its introduction. Details of the workings of this process will be found in the present report, in the matter descriptive of gravel operations near Jamestown, Tuolumne County, and at Dutch Flat, Placer County.

Device for transportation of ore in mountainous regions.-Mineral countries are nearly always mountainous, and the transportation of ores from the mine to au available mill-site or location for a furnace frequently requires a large outlay of money in the construction of a wagon-road or tramway, and a consequent expense in the hauling and transportation of ores, which prevent the profitable working of mines so situated. In order to obviate this difficulty, Mr. A. S. Hallidie, of San Francisco, has perfected an invention which he terms an "Endless Wire-Rope Way," a model of which, on a practical working scale, was exhibited in the fair of the Mechanics' Institute in San Francisco, in September, 1871.

This invention is one which promises to materially facilitate the working of quartz and other lodes located at inaccessible points, or where it is difficult to transport the ores from the ledge to the mill. It can be used at such locations for the delivery of material or ores in mountainous places or deep gorges; from the shore to vessels in the offing; for working up hill and down, and, where there is much descent, for economizing the power thus obtained by gravitation for any desired purpose. The invention consists in the use of endless iron or steel wire ropes, supported on peculiar sheaves, placed on posts, actuated by the gravity of the descending loads, or by an engine attached to a grippulley. The function of the grip-pulleys is to hold the rope so as to prevent its slipping in the groove. In general, the difference in altitude between the mill and the mine is sufficient to obtain by gravitation quite an amount of power, which is transmitted by the grip-pulleys for whatever purpose it is required, (and where there is no power obtained in this manner, it is given by a steam-engine.) The receptacles are small, self-dumping boxes which contain from 50 to 150 pounds of ore or other material. The rope travels two hundred feet per minute; the posts with the bearing pulleys on are usually two hundred feet apart, the hooks holding the ore-sacks being placed about fifty feet apart, and holding one hundred and fifty pounds of ore each. The rope is actuated by steam or water power whenever there is not sufficient descent to run it by the gravitation of the descending loaded carriers. In any event it is better to connect with the motive-power by gear, so as to secure uniformity of speed. The amount of ore delivered being four sacks of one hundred and fifty pounds, making six hundred pounds per minute, or 36,000 pounds per hour, or one hundred and eighty tons per day of ten hours. This can be increased or diminished at will. The cost of delivering the ore, including wear and tear of machinery, interest on outlay, and running expense, is about twenty-five cents per ton per mile. The cost of constructing such a line is from $4,500 to $7,000 per mile, according to the topography of the country. By its use material

can be transported from a higher to a lower, or from a lower to a higher point. In the last case, power must be applied, which can be done directly from a stationary engine at one end by means of the grip-pulley; in the first case, often no extra power will be needed, the gravity of the descending loads being sufficient to keep the rope in motion. Similar inventions have been made before, and the merit of this, therefore, depends on the peculiar construction and adaptation to the wants of the localities. One can readily see the great many advantages that this method possesses, from the fact that it requires neither road to be built nor expensive machinery; that it can be run at all seasons of the year, even when there are five or eight feet of snow on the ground; that it can be rapidly and cheaply constructed in the worst possible country; and that when there is sufficient grade, not only does it run itself by gravitation, but produces a motive power at both ends of the line. Running at four miles per hour, the boxes are carried down at one side of the posts and up the other, 400 to the mile, each delivering fifty pounds of ore, or ten tons per hour, and they can be run twenty-four hours per day.*

Paul's process.-The "electric dry amalgamating process," introduced by Mr. Almarin B. Paul, of San Francisco, has been tested in a number of localities within the past two years; and though the reports of its value vary, it is but fair to say that the inventor has received many sertificates of a very positive and favorable character.†

*This device is more fully described in a separate chapter of the present report, q. v. + The latest in date of these is given herewith:

DUN GLEN, NEVADA, March, 1872.

Mr. ALMARIN B. PAUL-SIR: Yours asking for statement of tests made at Sprague & Co.'s new mill at this place is received, and we here cheerfully comply as follows: We reduced 22 tons of ore from the Auburn mine, owned by Messrs. Wright & Wentworth, containing besides gold and silver, magnetic iron, carbonate oxide, and sulphuret of lead, and has always been considered of a very refractory nature. The 22 tons worked by your process paid $107 per ton. Eleven tons of same ore worked in pans paid $53 per ton. The bullion from your process runs as high as 989-1,000 fine.

We also worked the tailings of a lot of 20 tons of ore from the Monroe mine, which ore in the first instance was reduced by battery and pan process, at Essex Mill, and paid $8.14 per ton. The tailings from this lot yielded by your process $293.27. The bullion per battery and pan working was 584 fine; by your process, as per certificates of San Francisco Assaying and Refining Works, was 960 fine. The loss of mercury was less than half a pound per ton.

We also made a test on a small lot of iron sulphurets from Monroe mine, very closely concentrated, and which had been previously worked by battery and pan amalgamation, and which had been salted,oxidized, and worked several times previously--each time yielding some low-grade bullion. This lot was treated by your process, and to our astonishment obtained more metal in value than we had gained by all the several previous working, though very carefully done. The bullion by last working, as per certificate of California Assay office, was 999-1,000 fine.

We have now commenced on the "Lang Syne" ore, from a mine belonging to the "Great Central Mining Company of San Francisco," the results of which speak more for your process, and the great revolution the system is likely to inaugurate, and of its inestimable value, than any tests we can give you. That you may fully understand this we must particularize.

In 1863-24-25, the Lang Syne mine was worked, and in 1864 a mill erected for reduction of its ores, and over $100,000 expended and lost. The ore could not be made to pay.

The operation was pronounced a failure, and the mill removed. Tests of ten and twenty tons were also worked at the Essex Mill, having all the then modern improvements, with like unsatisfactory results. The mill just erected for the working of your process is built upon the same spot where the old mill stood. We have now worked a number of tons of a class of ore of which there are hundreds of tons in sight, with the result of $30 per ton and bullion 966 fine, being more than double the result obtained in the other mills.

The same renewed life which this locality has received through the introduction of

The process and machinery are described in Mr. Paul's circular as follows:

I start out with the idea, speaking only of mill ores, that the precious metals, in bulk of value, are in the most simple but delicate conditions, and require thoroughness in reduction, care, and chemical affinities, to unlock. That in their metallic state they are incased in their matrix in atoms so minute that the word "infinitesimal" hardly expresses the fineness. To meet these conditions it requires thorough pulverization, then delicacy in preparation, amalgamation, and precipitation. You will understand by this that as far as gold ores go-excepting the advantages of calcination-I regard desulphurization, with all its appliances, as an unprofitable expenditure of time and money, and often complicating nature's simplicity. I would further add that chlorination is only an expensive mode of getting a high percentage of gold, which can be obtained by the perfect working of this system, at less than half the expense.

In all ores are gaseous and refractory substances, atmospheric or other films, which coat the metal and create repulsion between it and the mercury. An increase of these repulsive elements takes place where the grinding of ore, iron, and mercury are carried on together. There is sufficient evidence to establish this point-every intelligent miner has experienced it. I must, however, for the less experienced, quote from one in high authority, (Overman, p. 280:) "All metals appear to have a tendency to float. in water, when in fine particles, some more than others. This is caused by a particle of gas, either air or water gas adhering to the particles of metals, which causes it to be light and float. Precious metals appear to possess more of this quality than others."

Again, the same author says: "Gold is by far heavier than silex, but we may observe, by means of a microscope, a multitude of fine particles of gold suspended in water, when we cannot detect the slightest particle of silicious matter." To sum up, as has been well expressed by another: "We have too long attempted to do by brute force what must be done with care and the gentle persuasion of affinities."

The practical working of the process is as follows: The ore is first heated, dried, then reduced dry by such machinery as best suits the views of parties and accomplishes the object of bringing the ore to the fineness of No. 14 wire cloth. The crushed ore is then conveyed to an iron pulverizing, preparing, and self-discharging barrel, where it is pulverized to flour in fineness and prepared for amalgamation, under heat. By heat, friction, and chemicals, it is put in what is termed an infinitesimal, electrical, live, and pure condition. Thus there is a combustion of all gases, destruction of rebellious films, and expulsion of atmospheric dampness, instead of which are created the greatest activity, attraction, and cohesion between the precious metals only and the mercury.

The ore thus prepared being so fine and light, and the metal to be operated upon infinitesimal, the question now comes how to produce effectual contact for amalgamation. To meet this point the ore is conveyed in its dry, heated, prepared, and electrical condition to an iron, wood, or earthen cylinder, to which is added from 20 to 25 per cent. in weight of mercury. The condition of the ore raises the temperature of the mercury, lessens its density, increases its volume, and the result is, the ore and mercury play together like water, and create the most thorough and complete intermingling. So perfect is the blending, that on examination with the naked eye hardly a particle of mercury is disclosed, notwithstanding the percentage to ore is so large. The mercury, in this finely-divided state, having been in continuous motion, rolling over and over on the surface and through the entire mass during the one hour given for amalgamation, it is reasonable to suppose has effectually done its work, and that the precious metals, no matter how fine, cannot escape a contact in this searching.

The harmony created between precious metals and mercury is finely illustrated by the fact that the baser metals are placed in antagonism, and consequently leave the mercury free from the fouling or sickening properties of the ore, no matter what it contains. It will be observed, too, that every infinitesimal particle has had its weight

your radically improved system, we are certain can be extended to others similarly situated by the introduction of your mills.

We will add that we have no difficulty in saving the mercury, and assert that the loss on all ores can be brought within that of pan amalgamation, and ordinarily very considerably less. Under all circumstances it is bright, active, and pure, and is used over and over again without any cleansing or retorting.

Your self-feeding and self-discharging pulverizing barrel is, without exception, one of the most complete reducers that we have ever seen. Its capacity is fully equal to your estimates of it, receiving ore from No. 14 wire cloth. The pulverizing of ore by quartz, instead of iron, is not only cheaper but much better. If desirable, we will, at any time, give results of our working.

Yours,

SPRAGUE & CO.

CHARLES D. SMYTH,

Superintendent of Sprague & Co.'s Mill, also Great Central M. Co.'s Mincs.