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By CLARESCE CARLETON SEJIPLE

(Wilkes-Barre Meeting, June, 1911.) AT a number of mines in eastern Nicaragua, 3.5- and 5-ft. Huntington mills are used for grinding gold-ore after a preliminary breaking in jaw-crushers. The smaller mills are made sectional to facilitate transportation to the more difficultly accessible mines. The capacity of the smaller mills is about 20 or 25 per cent. that of the larger, but in proportion to the quantity of ore ground they require more power and are subject to greater wear. The notes herein given are from records of the performance of the larger mills, but, in general, apply to the smaller also. THE NATURE OF THE ORE. The ore occurred as a series of flat veins in a highly-decomposed rock, probably alaskite. The primary mineralization comprised pyrite, pyrrhotite, marcasite, chalcopyrite, and quartz; the oxidation-products of which were chiefly hydrated iron oxide or limonite, chrysocolla, azurite, and malachite. The kaolinization of the feldspar of the country resulted in the admixture of a great quantity of clay with the oxidized ore. The quartz was sandy, imbedded in the clay; and probably the greater part represented the residue from the crushed rock in the fissures after leaching, and kaolinization of the feldspar. There was little vein-quartz in the unaltered primary sulphide ore. Only the oxidized ore was mined for the gold that it contained in amounts that averaged $4 per ton. No specks of gold were ever seen in the ore, and the gold obtained by panning was always exceedingly fine. The amalgamation-bullion was about 800 fine in gold and 60 to 80 in silver. The ore delivered at the mill contained from 5 to 15 per cent. of moisture; during the rainy season the quantity was much greater. The moisture and clay made the ore so sticky that it had to be raked over steeply-inclined grizzlies; it hung in the ore-bins,

Oct 1, 1911

By AIME AIME

COUNCIL PRESIDENT OF THE COUNCIL. CHARLES KIRCHHOFF NEW YORK, N. Y. (Term expires February, 1912.) VICE-PRESIDENTS OF THE COUNCIL. BENJAMIN B. LAWRENCE NEW YORK, N. Y. JOSEPH W. RICHARDS SOUTH BETHLEHEM, PA. ALBERT SAUVEUR CAMBRIDGE, MASS. (Term expires February, 1912.) S. B. CHRISTY BERKELEY, CAL. W. A. LATHROP PHILADELPHIA, PA. GARDNER F. WILLIAMS WASHINGTON, D. C. (Term expires February, 1913.)

Oct 1, 1911

By EDWARD B. DURHAH

(San Francisco Meeting, UCtober, 1911.) THE refinery at the San Francisco Mint takes the bullion purchased by the receiving department, and carrying more than 200 parts of precious metals in 1000, or, in mint parlance; over 200 fine, and separates and refines the various metals contained therein, using electrolytic processes exclusively. Bullion containing silver is treated in cells charged with a nitric electrolyte. These cells produce fine silver and leave a residue rich in gold. The residue from the silver-cells, together with crude gold-bullion, is treated in cells having a chloride electrolyte. These produce fine gold and leave a residue containing silver chloride. The latter is reduced to the metallic state with zinc and is then treated in the silver-cells. The various waste solutions and the wash-waters, after being freed from the bulk of their precious metals, still contain copper and other metals. These are removed by scrap-iron, and are then treated in the copper-cells, having a sulphate electrolyte. These cells produce pure copper, and collect a residue containing lead, some gold and silver, and all the metals of the platinum group that were in the bullion. This residue is relatively small, and is melted into bars and stored until sufficient accumulates to warrant treating it for platinum, etc. The refinery occupies three large and three small rooms. The large ones are, a melting-room, 30 by 34 ft.; a cell-room, 39 by 46 ft.; and a wash-room, 30 by 33 ft. The small rooms are used as foreman's office, laboratory, and generator-room, respectively. The methods here described are those in use in December, 1909, when notes for the present paper were taken.

Oct 1, 1911

By CHARLES DORRANGE

INTRODUCTION. CULM is a general term used in the anthracite regions for many years to denote a mixture of coal, bony coal and impurities which is sent to the refuse-banks. Thus, 35 years ago culm contained the pea and buckwheat sizes of anthracite; but to-day, and as mentioned in this paper, culm is used specifically to denote the material which passes through the smallest screen in the anthracite-breaker. The smallest size of commercial anthracite is known as No. 3 buckwheat, barley, or bird's-eye coal, and is ordinarily made through a round-punched plate having openings 3/16 in. in diameter, and over a round-punched plate with opening 3/32 in. or 1/16 in. in diameter. Thus culm will consist of coal, bony coal, slate, gravel, iron pyrite, etc., ranging in size from ? 3/32 in. down to dust. Other local terms for culm are " slush," " silt," and " dirt." The first experiments towards the utilization of anthracite culm by briquetting, and the first briquetting-work done in this country, were in 1872 at Port Richmond Piers, Philadelphia, Pa., by E. F., Loiseau.1 Clay was used as a binder and the finished briquette was water-proofed with shellac, etc. Excessive cost was given as the reason for discontinuing work at this plant. The Delaware k Hudson Co., in 1876, built a plant at Rondout, N. Y., which operated until 1880. Gas-tar was used as a binder, and anthracite screenings were briquetted for engine fuel. Excessive cost, poor results in firing, and the tendency of the fuel to cut the boiler-flues were given as the reasons for discontinuing the manufacture. The next plant was built by E. F. Loiseau about 1878, at Nesquehoning, Pa., near the No. 1 or Nesquehoning colliery

Sep 1, 1911

By George F. Becker

(San Francisco Meeting, October, 1911.) A MERE record of Emmons's professional career would very inadequately represent the man. That he was eminent we know, and our successors will realize in due time; but they must depend upon us for knowledge of a singularly wholesome, modest, unselfish personality, and of a character that did honor to a profession in which trustworthiness is indispensable: Those members of the Institute who met Emmons are his friends, and I never knew one of these who was not the better for that friendship. Emmons was born in Boston, Mar. 29, 1841, the son- of Nathaniel H. and Elizabeth (Wales) Emmons, and was named Samuel Franklin after an ancestor who was of the same family as Benjamin Franklin. He took the degree of Bachelor of Arts at Harvard in 1861, and soon afterwards went abroad to complete his education. From 1862 to 1864 he attended the courses at the École Impériale des Mines at Paris, lie e Beaumont and Daubrée being among his professors. The year 1864-1865 he spent at Freiberg under Cotta and other famous teachers; after which he spent another year in traveling through Europe. Like many other renowned geologists, he approached his ultimate profession from its economic side, and was thus from the first imbued with a sense of high responsibility in the promulgation of scientific opinions or conclusions. With hypotheses which were interesting merely because. they were ingenious or even plausible, he would have nothing to do. In 1867 he joined the Geological Exploration of the Fortieth Parallel at its organization under Clarence King, serving at first as a volunteer, but soon receiving a regular appointment. This expedition was the first one of purely geological character sent out by the United States Government. As Emmons has shown in his admirable presidential address on " The Geology of Government Explorations," its work was founded on a com-

Sep 1, 1911

By AIME AIME

COUNCIL. PRESIDENT OF THE COUNCIL. CHARLES KIRCHHOFF NEW YORK, N. Y. (Term expires February, 1912.) VICE-PRESIDENTS OF THE COUNCIL. BENJAMIN B. LAWRENCE NEW YORK, N. Y. JOSEPH W. RICHARDS SOUTH BETHLEHEM, PA. ALBERT SAUVEUR CAMBRIDGE, MASS. (Term expires February, 1912.) B. CHRISTY BERKELEY, CAL. W. A. LATHROP PHILADELPHIA, PA. GARDNER F. WILLIAMS WASHINGTON, D. C. (Term expires February, 1913.)

Sep 1, 1911

By Eli T. Conner

(Wilkes-Barre Meeting, June, 1911.) My connection, under a commission from the Councils and Board of School Control of the city of Scranton, Pa., with a recent investigation of mine-caves and the resultant damages to surface-improvements, has led to the preparation, at the invitation of our Secretary, of the present paper. It is notorious that there are, in the anthracite-fields, frequent subsidences of the surface, due to the removal of the coal beneath. No particular attention is paid to such occurrences, unless they happen to injure surface-improvements. Many caves have happened in Scranton and its vicinity, which have excited but little remark, since they have generally caused no serious damage. In August, 1909, a cave occurred in the Hyde Park section of the city, generally known as the West Side, which nearly destroyed school-house No. 16 and considerable adjacent property. 'Fortunately, there were no pupils in the building at the time; but the thought of the possible result, bad the usual number of pupils and teachers been present, aroused the public to the gravity of the situation; and the School Board employed engineers to investigate the case. Two reports were made by separate sets of engineers, which differed in some particulars. These differences were pointed out in the public press and magnified, and the consequent agitation of the subject was taken tip and greatly exaggerated by some of the metropolitan newspapers, giving to uninformed people the very erroneous impression that the whole city of Scranton was in danger of sinking into the bowels of the earth. All this tended to affect the credit of the city and to depress real-estate values. The matter was considered at a joint meeting of the Board of Trade, the Councils, and the School Board. The Hon. J. Ben. Dimmick, a former Mayor, suggested that it

Sep 1, 1911

By Douglas Bunting

(Wilkes-Barre Meeting, June, 1911.) WITH the gradual exhaustion of the upper veins in the anthracite coal-fields, the problem of mining at greater depths acquires increasing importance and demands the consideration of a number of important factors, one of which is the greater earth-pressure and the consequent necessity of stronger support o for the roof. Under the pillar-and-chamber system, almost exclusively followed in the Northern anthracite-field, the highest economy in mining is generally secured by leaving, on first mining, pillars only sufficient to support safely the overlying strata. As to the necessary size of such pillars, the opinions of mining experts are widely divergent. In establishing the width of chambers and pillars, the thickness of vein and its depth below the surface have received little consideration. For. instance, it has been quite usual to work both overlying and underlying veins with the same width of chambers and pillars, when the lower vein was two and one-half times as thick, and twice as fits below the surface, as the upper. In view of the generally-accepted theory that the crushing-strength of coal-pillars of the same base-area becomes less with increased height, it is probable, in this instance at least, that the most economical mining has not been secured. This question of adequate pillar-support is economically less important down to about 800 ft. than at greater depths; and it is with reference to mining at these greater depths that the study of the subject here presented has been prompted. The necessity of leaving larger pillars, involving greater mining-costs per ton and also smaller yields per acre, is one of the troubles of deep working. To mine without leaving adequate pillar-supports will result, sooner or later, in a squeeze. Limited areas, it is true, have been mined at certain widths of

Sep 1, 1911

By H. S. Geismer

INTRODUCTION. THERE are three general methods available for obtaining commercial brown iron-ore : hand-screening; washing; and washing and concentrating. Hand-screening has produced a large tonnage of ore in the past, but is rapidly falling into disuse, except as a preliminary step, largely because modern furnace-practice requires all foreign material to be separated from ores before they are delivered to the furnace, and hand-screened ores can rarely be made to fulfill that requirement. Another argument against hand-screening is, that the waste-pile often contains as much ore as the screen recovers. The operation known as hand-screening consists of throwing the ore-bearing material against a stationary inclined screen of 0.5- to 0.75-in. mesh, similar in construction to the screens employed in sand-pits. The recently-prospected brown-ore deposits of Cuba seem to offer possibilities for hand-screening not possessed by the average American deposit, since these ores are not associated with worthless clays. Washing, and washing and concentrating, may be discussed together, since concentrating is never practical on brown iron-ore, except to treat ores that have already been washed. (Strictly speaking, washing might be classed as concentrating, but it is never so designated by brown-ore men.) The various steps of removing ore-bearing material and converting it into ore suitable for blast-furnace use, may be grouped under five heads: loading for transportation ; transporting ; feeding into the washer; washing; and concentrating. These five subjects will be considered in consecutive order. Each of these successive steps may be accomplished in a number of different ways, the choice depending entirely upon the character of the ore-bearing material to be treated.

Aug 1, 1911

By HUNTINGTON ADANS

(Wilkes-Barre Meeting, June, 1911.) THE arrangement of a flow of cyanide-pulp through Pachuca tanks in agitation, so as to permit a continuous process, instead of alternate filling, agitation, and emptying, has been proposed by various writers within the last two years, and more particularly by A. T. Grothe, agent for the Brown patents on Pachuca tanks in Mexico. It was first put into practice, I believe, by M. H. Kuryla at the Esperanza mine in El Oro, Mexico. The starting of agitation in Pachuca tanks after filling may offer no serious difficulties with ores which do not settle rapidly in such tall tanks; and the adaptation of the tanks to continuous agitation under such conditions may give simply a somewhat more convenient method of treatment and greater agitation-capacity for a given number of tanks, because of the saving -of time lost in filling and discharging. But in the treatment .of pulp which tends to settle rapidly, as in the cyaniding of concentrates or of the whole pulp of ores containing heavy sulphides, the packing of the slime at the bottom may, cause much trouble. The use of the radial air-pipe attachments near the top of the cone and of the air-valve outside of the air-lift .tube at the bottom may obviate the difficulty to some extent; but the action of the radial air-pipes on the cone-sides is that -of a sand-blast, and their continuous use cuts through the tanks. Moreover, even when these pipes are used, some pulps will pack tightly below them in the cones. Under such conditions the use of Pachuca tanks with intermittent filling and discharging becomes a troublesome process. Time is lost in ,starting agitation; large quantities of compressed air are wasted; pulp is blown over the tank-tops; and not infrequently it may be necessary to dig out the bottoms of tanks by hand. This trouble is the only important one occurring in the use of Pachuca tanks; and, since it is caused by intermittent filling, the .arrangement of a continuous flow of pulp from tank to tank,

Aug 1, 1911

By James Gayley

(Wilkes-Barre Meeting, June, 1911.) THE paper presented to the Institute in 1910, by H. 0. Hofman, on Recent Progress in Blast Roasting,1 has called the attention of the iron industry to the adaptability of these processes to the reclamation of by-products such as flue-dust and blue billy, and the better preparation of concentrates and fine ores for use in blast-furnaces. The waste of valuable iron-ore through the production of flue-dust has increased at an enormous rate, and much of it has in reality been wasted as far as future recovery is concerned. Only in recent years has a possible future value been recognized, and the material stored. The increased use of Mesabi ores, which carry considerable fine ore, is principally responsible for the great increase in the production of flue-dust. The amount of fine material that is carried over depends on the fineness of the material and the velocity of the gases, and also to a very great extent on the regularity or irregularity of the working of the furnace. Attempts to recover a part of this loss have been made by recharging a portion of the production into the furnace, but as this material has been once carried out from the furnace, it is naturally in good shape to be carried out again. A recent practice at some works, is to soak the flue-dust thoroughly with water to give it more cohesiveness, but by many this is considered of doubtful advantage in the furnace, and the gases are in consequence heavily laden with moisture. There are vast deposits of magnetic iron-ores in the United States and Canada that are too low in iron for use at the present time, but which can be economically concentrated into very rich material ; in many cases the fineness of crushing necessary to secure proper concentration has prevented their

Aug 1, 1911

By Samuel D. Warriner

(Wilkes-Barre Meeting, June, 1911.) THE dealings between concentrated capital invested in the conduct of our various industries and the combinations of labor known as "trade union organizations," have produced not only in the United States, but abroad, many novel methods of negotiation between employers and wage-workers. The size and strength of these organizations have destroyed the personal elements formerly governing the dealings between employer and employee and have produced various forms of trade-agreements now in more or less successful operation. The difficulty, however, has- been to secure consent of both parties to an equitable agreement. For this purpose there have been devised various forms of arbitration, either compulsory under the shadow of governmental legislation, or voluntary by mutual agreement. But these have not been altogether successful from a technical stand-point, for the reason that a compromise has generally been necessary, and in an effort to reach an agreement, terms have been made which have been neither fair nor satisfactory to either of the contending parties. The Anthracite Board of Conciliation represents one of the few thoroughly successful courts for the settlement of trade-disputes, if not the only one which has yet been evolved. The prestige of this board rests upon its successful treatment of the labor-troubles of the anthracite region for a period of more than eight years, and upon the fact that it has been able not only to reach decisions based upon the merits of the controversies, but to enforce its decisions upon both the employees and the employers. It has never been obliged to shape its conduct to secure the consent of the contending parties, and its decisions have been strictly and, in the main, cheerfully observed. The remarkable feature of this board has been that it has

Aug 1, 1911

By James E. Little

(Wilkes-Barre Meeting, June, 1911.) OF the several extensive deposits of brown iron-ore in Cuba, including those of Mayari and Moa, that of Mayari was the first to be systematically explored, and was selected as the scene of the first operations in the development of this class of ore. Construction-work, begun in the spring of 1907, involved the building of 16 miles of standard-gauge railroad and two large double-track inclines, the installation of mining-machinery, a nodulizing-plant, power-plant, shops and shipping-facilities, and the dredging of an extensive basin for deep-draught vessels. Unusual weather-conditions delayed the completion of portions of this work so that the entire plant was not in operation until December, 1909. The ore in its natural state contains a very large percentage of water, which increases to some extent with the depth below the surface. Near the surface it is red in color, with somewhat granular structure. The color gradually changes with depth, finally reaching a bright yellow. The consistency also changes towards, the bottom to a clay-like, sticky mass. The relative proportion of red and yellow ore is quite variable; in some places the yellow reaches close to the surface, while in others the red extends almost to the underlying serpentine. Fig. 1 is a map showing the Mayari division of the Spanish-American Iron Co. The ore lies on an irregular plateau about 15 miles long and 5 miles wide at the widest point, entirely covered with pine trees and brush, which grow directly on the ore. The elevation at the northern extremity, which is approached by the railroad, is about 1,700 ft. above sea-level. At the southern end the general elevation is about 2,000 ft. Ore is removed by means of scraper-bucket excavators and steam-shovels, these machines loading into special standard-guage, side-dump steel cars of 100,000 lb. capacity. A short haul

Aug 1, 1911

By John Birkinbine

(Wilkes-Barre Meeting, June, 1911). MODERN advances in practically all lines of industrial development have occurred in such rapid succession, and have been accepted so readily as accomplished facts, that a retrospect surprises us, by showing how comparatively few of the acknowledged factors of improved conditions may be considered as old. While these advances have not been confined to any country, they have been more pronounced in some than in others, and nowhere more so than in the United States, the population of which, having multiplied nearly three-fold between 1870 and 1910, demanded a proportionately greater increase in materials, supplies, and manufactured products. It therefore appears desirable to discuss mainly conditions in the United States, as concrete evidence of industrial progress throughout the world. Looking backward for but three generations, we may trace the introduction and development of canal- and steamboat-navigation; railroad-transportation; artificial illumination beyond that furnished by candles and lard-oil; quick communication by mail, and subsequently by telegraph or telephone; the manufacture of iron, beyond forms of small dimensions; the production and utilization of steel in large quantities; the economic use of mineral fuel, oil and gas, etc. The practical coincidence of the fortieth anniversary and the 100th technical meeting of the American Institute of Mining Engineers, offers temptation to recall and compare the conditions of mining and metallurgy in or about the years 1871 and 1911. A complete resume would cover phenomenal changes in mining-methods and equipment by which the output of individual exploitation has grown from scores to hundreds and even thousands of units in equal time-intervals. Extension of operations in depth and area, demanding machinery of great power

Aug 1, 1911

By Charles R. Keyes

I. INTRODUCTION. FOR a period of several years, and in a large number of cases, the Metallurgical Laboratories of the New Mexico School of Mines were employed in umpire work. During this time many important local problems were solved. Against the results of careful chemical analyses of ores, assay-returns were often checked. In many cases the assay-methods of mine and custom-smelter were compared, and both often found faulty for the ore concerned. A wide range of ores was covered. Many of the chemical analyses and assays were made by Dr. F. C. Lincoln, Professor of Metallurgy, now of the Montana State School of Mines. A varied series of instructive assays was prepared by Prof. R. B. Brinsmade, now of the West Virginia State University. Single assays and given series of tests were undertaken by H. T. Goodjohn, now chief chemist to the Cia. Metalurgica de Torreon, Coahuila, Mexico; by H. J. Hubbard, now superintendent of the Butters Divisadero Mines, Jocoro,. San Salvador, C. A.; by E. D. Morton, now superintendent of the Arizona & Nevada Copper Mining Co., at Lunning, Nev. ; and by A. W. Edelen, now superintendent of the Angangueo Unit of the American Smelting & Refining Co., in Michoacan, Mexico. A critical comparison of assay-methods that were found to be followed in the case of certain gouge-ores mined in the Mimbres range in New Mexico, and about which there had been much controversy, was made by D. F. Riddell, then Acting Professor of Assaying, and now superintendent of the Providentia Mines Co. of Parral, in Chihuahua, Mexico. To him is due the credit of much that is contained in the following notes, which be has generously permitted -to be used in advance of the publication of the complete results.

Jul 1, 1911

By W. L. Saunders

(Wilkes-Barre Meeting, June, 1911.) I. INTRODUCTION. IT is now generally admitted by experts that at least so far as rapid progress is concerned the Alpine system of tunnel-driving is superior to any other. This is perhaps natural in view of the record of experience in driving tunnels through the Alps. These great mountain-chains cannot be treated in the ordinary way by shaft-sinking and driving headings, thus multiplying the points of attack. The work must be done from the ends only, hence speed in driving is of the utmost importance; and, as necessity is the mother of invention, the concentration of effort to make progress has resulted in an organization and in mechanical appliances that have produced results so much in excess of the usual practice, even in America, that a discussion of the subject in detail should be of much value to the engineer and contractor. The first Alpine tunnel was the Mont Cenis, length 7.5 miles, driven with a progress that averaged about 7.75 ft. per day. Next came the Saint Gothard, 9.5 miles long, 18 ft. per day; Arlberg, 6.5 miles long, 27.25 ft. per day; Simplon, 12.25 miles long, 36 ft. per day. The figures represent progress when driving from two headings, so that by dividing them in two we get the daily single-heading progress. The latest of the Alpine tunnels is the Loetschberg, now being driven. In this work the world's record has been beaten by a single day's record in one heading of 36 ft. and by an average daily record in. one heading of 29.5 feet. The Alpine range forms a natural barrier between a large section of northern and southern Europe. This range extends from the southeast of France to the frontier of Hungary, between Italy and the plains of southern Germany. The contour

Jul 1, 1911

By S. Arthur Krom

(Wilkes-Barre meeting, June, 1911.) RECENT experiments indicate that the usual type of concentrating-table is not only poorly adapted to produce the desired results, but also is based upon an incorrect principle, namely, the use of riffles to perform the work of stratifying the various minerals. We have heard a good deal about riffles for concentrating-tables; exhaustive experiments have been made to discover the proper form of riffle, or to prove the superiority this or that form; disputes and patent-litigation have arisen over the matter of riffles, and thus many have been led to believe that the riffle is the saving-device upon which the process of concentration depends. In the present paper it is proposed to show that the riffle is greatly overrated as to the part it performs in the concentration of minerals, and that, in the near future, it may possibly be eliminated entirely from that process. The experiments in question have shown that the troublesome riffle can be considered of secondary importance at the most, and should be so classed in the construction of a concentrating-table built upon the right lines. The action of any form of riffle on a concentrating-table is such as to upset and retard the process of settling and stratifying the various minerals on the table-deck. From the deck of a riffled table no concentrates can be delivered until the deck is "bedded," that is, until a sufficient amount of metallic values have been fed to the table to spread over a large portion of the deck, forming a substratum of the heavier minerals. This substratum must be maintained by the feed within quite narrow limits, and directly proportional to the rate of discharge from the table, in order that the bed shall not be lost. On the other hand, the riffles having a very lim-

Jul 1, 1911

By AIME AIME

LOCAL COMMITTEES. EXECUTIVE.-W. A. Lathrop, Chairman; R. V. Norris, Secretary; S. D. Warriner, Treasurer; Irving A.. Stearns, W. J. Richards, H. S. Drinker, C. D. Simpson. GENERAL RECEPTION.-Irving A. Stearns, Chairman. Archibald, James, Jr., Pottsville. Lawall, E. H., Wilkes-Barre. Ashley, H. H., Wilkes-Barre. Lentz, W. 0., Mauch Chunk. Ayres, WV. S., Hazleton. Lewis, Albert, Bear Creek. Beard, J. T., Scranton. Loomis, W. H., Jeddo. Bridgman, J. C., Wilkes-Barre. Markle, Alvan, Hazleton. Bunting, Douglas, Wilkes-Barre. Markle, John, Jeddo. Chase, F. M., Wilkes-Barre. Neale, J. B., Minersville. Coroner, Eli T., Scranton. Norris, R. V., Wilkes-Barre. Cote, E. B., Jr., Drifton. Oliver, Paul A., Oliver's Mills. Davies, W. H., Hazleton. Owens, W. D., Pittston. Davis, H. G., Dorranceton. Pardee, 1. P., Hazleton. Dodge, W. F., Wilkes-Barre. Quin, R. A., Wilkes-Barre.

Jul 1, 1911

By Charles R. Keyes

I. INTRODUCTORY. IN the dry regions of the globe many silver-deposits display certain remarkable features which at the same time are so totally unlike anything met with among ore-bodies elsewhere, that they have long presented exceptional difficulties not only to a satisfactory explanation of their origin, but to economical milling. A most striking peculiarity of these ores is the haloid character of many of their bonanzas. To this fact more than to any other may be ascribed most of the unusual uncertainties of mining-operations in desert countries-the marvelous local richness of the ores under certain conditions and the often abrupt transition, to utter poverty; the inadequacy of ordinary prospecting customs and the constant devising of new exploratory methods; the unaccountable losses in smelting and the continual change in treatment-practice. For these anomalies certain climatic conditions seem to be chiefly responsible.

Jul 1, 1911

By FRED T. WILLIANS

INTRODUCTION. THE Park City mining-district is distinctively a camp of few properties, 5,000 acres, or one-third of the entire district, being under the management of but three companies. As a rule, the ore-bodies lie deep, with no outcrop, except where erosion has formed the deeper canyons and gulches. Ontario canyon exposed the famous Ontario ledge, and Woodside gulch showed the first ore of the Silver King Coalition mine. The Quincy ore-bodies were first brought to light in upper Empire canyon, and Thaynes canyon was instrumental in aiding the prospector during the early days of the camp. There are 22 shafts which have reached a depth of at least 500 ft., ten a depth of 1,000 ft., five a depth of 1,300 ft., and two a depth of 2,000 ft. The amount of lateral development has been proportionally extensive, including six long tunnels, four of which are in 3 miles, with a fifth now being driven. The Ontario lower drain-tunnel is now more than 4 miles long. The formations are sedimentary, dipping about 30° NW. and N., and traversed by many fissures, dikes, and faults. The principal ore-bodies are found associated either with the contact of the basal Ontario quartzite and the overlying limes, or on a quartzite stratum within the limes, or in the fissures, or along some of the porphyry dikes. The district covers the intersection of the Uintah and Wasatch ranges, which explains the existence of large folds and faults, and fissures of great length, width, and depth. In a general way, the geology of the district consists of a basal quartzite dome, which has been exposed by erosion at the Ontario property. The Ontario fissure lies entirely within this formation. Flanking this dome on the west, north, and east lie

Jun 1, 1911