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By J. Wesley Pullman

It is stated by Dr. Tuttle in a paper read before the New Jersey Historical Society, that the celebrated Dickerson mine at Succasunna, Morris Co., N. J., yielded ore, about as early as 1710, for use at the Whippany forge, on Rockaway River, between Rockaway and Boonton. The ore was, for some time, free to all who chose to dig it. The tract embracing the Dickerson mine mas taken up, on account of its minerals, in 1713 or 1714, by John Reading, who sold it in 1716 to Joseph Kirkbride. John Jackson built a forge in 1722 on the Rockaway River a mile west of Dover. The ore here worked was probably chiefly from the Dickerson mine, but a portion may have been Hibernia. Hon. E. D. Halsey, of Rockaway, K. J., writes me: It is quite possible that the ore was at first taken from the outcrop of Hibernia by anybody who wanted it. The property first had an owner, May

Jan 1, 1886

By L. F. Pett

ALTHOUGH Kennecott's orebody has long been outlined, it is still necessary to define further its limits. This mine, long an advocate of churn drill methods, recently supplemented its practice by using a diamond drill. So far, the diamond drill holes have been along the main canyon floor which traverses the mine area. This zone, highly fractured, is cut by numerous friable quartz veinlets encountered within the porphyry. These veinlets, formed by filling contracted porphyry fractures with hot, siliceous, mineral-bearing solutions, are often more highly mineralized than adjacent porphyry. They pulverize on contact, yielding only slight amounts of core.

Jan 7, 1951

By AIME AIME

READERS of a technical paper, or the audience if the paper is presented orally, judge the paper on several counts. The September 1940 issue of MINING AND METALLURGY contained an excellent short article by S. Marion Tucker en- titled "Are You Going to Present a Paper," which considered the general subject of presentation. In it Dr. Tucker referred to the large number of poorly prepared and badly delivered papers that are presented annually before the large number of technical and other societies that meet regularly, and he stressed the point that good delivery, length of paper, content, and composition are of great importance. All of Dr. Tucker's points were well taken; however, good illustrations are equally important in explaining certain phases of some papers.

Jan 1, 1941

By R. Gilman Brown

INTRODUCTION. MINES are interesting by reason of what they have done for man, or of what has been done for them by nature. Not all are interesting on both scores. Many profitable mines are commonplace to the geologist; and many presenting unique geological conditions have been sad failures commercially. The Standard group at Bodie has produced in 25 years, $14,500,000, paying $5,000,000 in dividends.' On the other hand, this output has been mined (almost wholly above the 1,000-ft. level) from a system of more than 100 veins, ranging in thickness-from 0.5 in. of "specimen rock" to 30 ft. of clay and quartz; distributed through a zone about 2,000" ft. in width, and representing from three to five distinct periods of formation. This group, therefore, by reason of its industrial record as well as its geological features, may fairly be regarded as doubly interesting. The Bodie district occupies an island of recent (Tertiary) hornblende-andesite, surrounded by a complex of igneous rocks and breccias. It lies at the summit of the eastern foot-hills of the Sierra Nevada mountains, and within the Great Basin, a few miles from its western edge, marked here by Mono lake on the line of the Great Fault. The average elevation of the outcroppings of the veins may be taken at about 5,700 ft. The andesite projects from south to north in a great tongue, 12,000 ft. long and 5,000 ft. wide, reaching an extreme height at the northern end of perhaps 1,000 ft. above the adjoining small canyons. These separate it from the main mass of the foot-hill

Jul 1, 1907

By Marie Kinzel

LOS ALAMOS, New Mexico, the birthplace f the atomic bomb, is one of the most famous-and mysterious-places in the world. It leaped into fame on Aug. 6, 1945, when the first atomic bomb burst over Hiroshima. Unheard of until that day, its present life is as hidden from most people as was its very existence in pre-Hiroshima days. Then, those who did know of it dared not breathe their knowledge. "What do you tell your wife when you go to Shangri La?" was the favorite quip of the few consultants who made regular trips from east or west to Los Alamos during the tense months when the bomb was in the making. Security regulations made it impossible even to hint at the rigid secrecy surrounding the project. The puzzled wives in question knew only that their husbands had top priority on airplane flights to Albuquerque. When they had verified the safe arrival of the flight, they undoubtedly breathed a sigh of relief. If they could have visualized the rest of the trip, the sigh of relief would have been replaced by a state of tizzy, until a telegram came saying "Arriving home on Flight X" (on a nice safe airplane).

Jan 1, 1946

By J. Brian Eby

As is generally understood, the word geophysics means literally ?the physics of the Earth? and the science of geophysics is therefore that which treats of the study and measurements of the various physical properties of the Earth. The broad and general study of the elastic, the gravimetric. or the magnetic properties of the Earth as a whole belongs to the general science of geophysics. The detailed application of this science to rocks of shallow depth and in small areas for the purposes of ascertaining data on their character and structural attitude gave rise to the present well-known science of ?applied geophysics.? Since the discovery of enormous new quantities of oil, gas, and sulphur has been by far and wide the principal benefaction of geo-physics in the United States, this paper will refer only to geophysical methods employed in the search for these particular minerals. The application of methods and appliances originally used for geophysical research to the solution of the practical problems of finding new oil-fields, plus the counterflow or new and highly refined techniques and Instruments from the company and consulting geophysical research laboratories and into non-economic geophysical research, has provided another case of that gen-eral cycle of events which is familiar to all scientists. That this closed-circuit flow or scientific current has been tremendously important to the whole science of geophysics is probably well known to all members of this audience, but the gen-eral status of the exploratory geophysical arts as now used In the search for new oil-fields, the scales on which different methods are being used, the magnitude of the costs involved, and the far greater magnitude of the practical results achieved may not necessarily have come so directly to your attention. It is, I understand, for this reason that this paper has been sug-gested, and I shall seek to provide the information requested by using as case-illustrations those changes in the oil-reserve picture for the United States as a whole, and for the Gulf Coast, California, and Illinois Basin regions in particular, which have occurred in the period of the past 17 years, during which time oil-field discoveries have proceeded at a rate which served to build up known and readily-available (or proven) oil supplies to a reasonable figure, and have dispelled the fears of a serious oil shortage during any period for which valid fore-casts can be made. Not that geophysical-prospecting methods have alone been responsible for this transformation, but they have an indispensable and leading part in the picture of exploration and production-to which geophysics, geology, engineering, and general technical progress have jointly made contribution. So far as the United States as a whole is concerned, its total proven, probable, and possible oil reserves (discoverable and recoverable by then-known methods) were estimated at about nine billion barrels in 1920, whereas proven reserves alone are now com-puted at about 16 billion. In 1920 the driller in ?wild-cat? territory was faced with the knowledge that for every new oil-field opened by a successful well, from 20 to 100 unsuccessful wells would have to be drilled and, in some territories, that the chances for a discovery were really less than one in 100 for new drilling, in contrast to which may be cited the record for the past year in parts of Louisiana where the 67 wells drilled opened 16 new oil-fields, that is to say, where the score of hits to misses was increased to approximately one out of four.

Jan 1, 1940

By Dudley L. Davis, E. C. Peterson

INTRODUCTION THE Darwin District is 30 miles east of Olancha which is 220 miles north from Los Angeles via U. S. Highway No. 6. The ore deposits occur in the Darwin hills that have been elevated above the Darwin Plateau by typical basin and range-type faults. Some of these faults have been active quite recently as shown by the displacement of Quaternary (?) basalt flows and the rejuvenation of erosion in Darwin wash. The ore bodies occur as fissure fillings and replacement of favorable beddings in a thick series of Paleozoic limestones, dolomites, shales and quartzites. Rich oxidized lead-silver ores were discovered in the early seventies. By 1875, Darwin had a population of about 5000, and by 1880 several small mills and smelters had been built. Early exhaustion of surface ores, the isolated location of the district, and fluctuation of metal prices caused intermittent operations until World War II. The district production is estimated at about $3,000,000 prior to 1900 and perhaps $4,000,000 between 1900 and 1945 when Anaconda purchased the major producing mines. For the past two years, daily production has averaged 75 tons of direct shipping and 150 tons of milling-grade ore. At present, 300 tons of mixed oxide and sulphide ore are treated by flotation, the oxidized lead minerals being activated by addition of sodium sulphide after galena and sphalerite have been recovered from the circuit. Extraction averages 85 pct of the lead, 80 pct of the silver, and about 33 pct of the zinc in a bulk concentrate. The mill is designed so that minor changes permit selective flotation of pyritic lead-zinc ores encountered at depth. GENERAL GEOLOGY The oldest rocks in the Darwin hills are a series of Paleozoic limestones, dolomites, shales and quartzites probably Pennsylvanian in age. These rocks have been intruded on the west by the Coso granite batholith and on the east by a granodiorite stock. Numerous sills and dikes grading from orthoclase granite to gabbro are exposed in the underground workings. The sedimentary rocks have been considerably folded and faulted, the most prominent structure being a northwest pitching anticlinal fold, the crest of which lies just west of the ridge line of the Darwin hills. The east limb of this fold has been intruded by the granodiorite stock and east of the stock the sediments show several closely spaced anticlines and synclines. The minor flexures on the west flank of the major fold are structurally important in localizing the ore in the Defiance and Essex mines of the Darwin group. There are three principal systems of faulting and fissuring, most of which are post-intrusive and premineral in age, with minor amounts of postmineral movement. The Darwin tear fault is the largest, most persistent fault in the district. It strikes N 60 to 95°W, dips steeply south and is traceable for about 1o miles. It is a normal

Jan 1, 1947

By T. F. Witherbee

It is proposed to give, first, a description of the works; second, a report of the first six months of the present blast; and third, such improvements as have been suggested by the practical working. The site selected for this furnace was, at the time of commencing work, October, 1872, entirely covered by the navigable waters of Lake Champlain. A coffer-dam was first built of cribs of round timber filled with stone, forming three sides, while the shore answered for the fourth. Considerable excavating was done with a steam-dredge, a hole being left for it to pass out. The opening was then built up, and the cribbing banked up with blue clay from the bottom of the lake, to render it water-tight and the dam pumped out; the remainder of the excavating being done by hand. All of the foundations, with the exception of the elevator-tower, and fifteen feet of the east side of hot blast, rest on the Potsdam sandstone, which forms the shore line, dipping into the lake at an angle of fifteen degrees. Owing to jogs in the formation, a much greater depth was found necessary than was at first anticipated, the foundation under the stack

By Albert Sauveur

IT is not without some hesitation, and even misgiving, that I venture into a discussion of the now classical Roberts-Austen Roozeboom diagram, lest I too fail, like so many other writers, in giving a satisfactory and logical explanation of these interesting curves. Roozeboom's original diagram is reproduced in Fig. 1. The generally accepted meaning of the various curves has been so often described before this Institute that it will suffice to recall it briefly before passing to my own interpretation of the changes involved.

Nov 1, 1906

By J. L. Bray

ACCELERATED programs, as discussed in this paper, refer to the year-around operation of a college or university with three sixteen-week or four twelve-week terms per year, with pauses between sufficient only to allow the administrative group to perform their functions. In most engineering schools, under such conditions, the conventional four-year course can be condensed to two years and eight months. These accelerated programs of study, which now exist in most of our technical institutions, were forced upon us under the influence of the outburst of wartime patriotism, perhaps one might go so far as to call it hysteria. Many of us felt and hoped that these programs were temporary expedients, but the cold hard threat of permanency now rears its head; consequently we should examine the merits and shortcomings of the new order, and evaluate its effect on our educational system, since it may persist in some form in the postwar years, because of the changing political and financial situation. Many engineering students are being educated in state supported institutions

Jan 1, 1944

By D. Harrington

ANNUAL or necessary inspections and investigations of coal mines for various purposes were made possible through the Federal Coal Mine Inspection Act of May 7, 1941, which authorized entry to the Secretary of the Interior through the Bureau of Mines. Primary object of these inspections is to obtain information pertaining to health and safety conditions. Among the purposes for which the data are to be used, are annual reports to Congress, the publication of inspection reports, and the compilation and publication of statistics. The act states that inspections and investigations shall be made by employees of the Bureau of Mines, who shall co-operate with other bureaus of the U. S. Department of the Interior, as well as with the official mine-inspection, safety cr health agencies of the several states and territories. The act specifies that a coal-mine inspector shall have "the basic qualifica-

Jan 1, 1946

By T. F. Witherbee

IT is proposed to give, first, a description of the works ; second, a report of the first six months of the present blast; and third, such improvements as have been suggested by the practical working. The site selected for this furnace was, at the time of commencing work, October, 1872, entirely covered by the navigable waters of Lake Champlain. A coffer-dam was first built of cribs of round timber filled with stone, forming three sides, while the shore answered for the fourth. Considerable excavating was done with a steam-dredge, a hole being left for it to pass out. The opening was then built up, and the cribbing banked up with blue clay from the bottom of the lake, to render it water-tight and the dam pumped out; the remainder of the excavating being done by hand. All of the foundations, with the exception of the elevator-tower, and fifteen feet of the east side of hot blast, rest on the Potsdam sandstone, which forms the shore line, dipping into the lake at an angle of fifteen degrees. Owing to jogs in the formation, a much greater depth was found necessary than was at first anticipated, the foundation under the stack

Jan 1, 1876

By E. G. Leonardon, C. Schlumberger, M. Schlumberger

Last year the authors presented a paper that discussed the various electrical measurements they perform in drill holes, which they name "electrical coring."' The object of the present paper is to give a brief account of the points of scientific interest that have been elucidated by further field work and laboratory research, as well as the economic results that have been attained recently. The practical examples given in this paper are drawn, for the most part, from the field work performed in Russian oil fields during the years 1931 and 1932. This is due to the fact that, thanks to the comprehensive cooperation of the Russian geologists and scientists, the authors are allowed to make public a large amount of recant information. In other countries in which the authors are engaged in similar work, the competition between private companies makes it imperative, for a considerable lapse of time, to avoid publication of the results obtained. The following points will be discussed successively, under separate headings: 1. Electrochemical phenomena in drill holes. 2. Stratigraphic correlations and tectonic studies. 3. Relations' between the productivity of oil horizons and their electrical resistivity. 4. Location of coal seams. 5. Summary and conclusions. Electrochemical Phenomena in Drill Holes Technical Publication 462l described the author's discovery concerning the existence of important differences of potential spontaneously gener-

Jan 1, 1934

By I. C. Edwards, W. J. Dengler, D. F. Lillie

By 1959 the milling plant of Bicr oft Uranium Mines Ltd. had been in operation for two years. During this time many changes, both physical and chemical, had been made in an effort to improve plant efficiency. Investigational work had been facilitated greatly by the fact that the Bicroft mill consists to a large extent of two parallel circuits; however, the number of interrelated variables is great, and it is difficult to measure, let alone control, all of them simultaneously. The Bicroft mill staff feels that much progress has been made, but there is much yet to be done and many questions still to be answered. The Addendum outlines noteworthy developments to the fall of 1960. The property of Bicroft Uranium Mines is located in Cardiff Township in the Highlands of Haliburton County, southeastern Ontario, some 140 miles northeast of the city of Toronto and 70 miles due north of Lake Ontario. The ore-bearing dikes are classed as mafic. nonsegregated, syenite and granite pegmatite. Microline, microline perthite, quartz, sodic plagioclase, and pyroxene or biotite are the main constituents with uraninite, uranothorite, fluorite, titanite, cryolite, calcite, pyrite, pyrrhotite, and molybdenite as important accessories. The mill was designed for a nominal capacity of 1000 tpd with all sections except grinding, leaching, and clarification capable of 1500 tons. Feed was entered to one mill unit on Oct. 29, 1956, and to the second parallel line on November 13. The total feed rate was at 1000 tpd on November 15. The first precipitate was produced on November 12. By August 1958 the average entry had been increased to 1410 tpd without the installation of any additional major equipment. The overall recovery has been greater than 93.0 pct on several months, but a recovery of 92.5 pct appears to be most economical. Operating time for eight months in 1958 has been 97.1 pct although all grinding mills were relined during this period. A generalized flowsheet is shown in Fig. 1 and the plant layout in Fig. 2. The ore is crushed in three stages to -3/8-in. and then is wet ground in two stages to approximately 50 pct -200 mesh. The pulp is thickened to 68 pct solids and agitated by air for 33 hr at a pH of 1.9 as maintained by the addition of 93 pct sulfuric acid. Separation of the uranium-bearing pregnant liquor from the residue is accomplished by five-stage countercurrent decantation (CCD), following which the liquor is clarified for removal of fine slimes. The clarified liquor is treated in the ion exchange equipment in which both the upgrading of the solution and the removal of some impurities is accomplished. Addition of magnesia to the high-grade eluate from ion exchange precipitates the uranium as sodium-magnesium diuranate. After being filtered and dried this precipitate is packaged in drums for shipment. The residue from CCD and the barren solution from ion exchange are neutralized by the addition of lime and pumped to the tailings disposal area. CRUSHING All crushing is done on surface in a conventional three-stage unit consisting of a 36x48-in. Birdsboro Buchanan jaw crusher, a 4 1/4-ft standard Symons cone crusher, and a 4-ft Symons shorthead. Both the two primary and the two secondary screens are 4X 8-ft Symons rod decks. Moisture content of the feed ranges from 3 to 4 pct. In the initial installation the primary screens were equipped with 5/16-in. rods at 1 1/4-in. spacing and the secondaries with 5/16-in. rods at 1/2-in. spacing. With this arrangement the average crushing rate was better than 180 tph. To reduce the work required of the grinding circuit as tonnage was increased, several changes were made in the crushing circuit. By September 1957, both secondary screens had been reduced to 3/8-in. spacing, and rod size had been reduced to 3/16-in. to provide increased open area. Average throughput was reduced to 160 tph. Later, 50 pct of one primary screen was decreased to 1/2-in. opening to better balance the load between the two cone crushers. In May 1958,

Jan 1, 1961

By John Howe Hall

One's first thought, upon being chosen to deliver the Henry Mario Howe lecture, is of pride at being selected for this post of honor, but ther succeeds immediately a deep sense of the Obligation thereby incurre to give of one's very best in order to make a contribution worthy of hir in whose memory these lectures are given. One who had the goo fortune to be associated with Henry ill. Howe, upon sitting down t prepare such a paper as this, irnrnediately falls to musing upon thc day when his face and his footfall were familiar from constant association, an recalls with singular vividness his active figure, his mobile, alert face, an his keenness in penetrating to thc corc of the subject under discussior Like Dr. Mathews, I was a young man when I first worked under hi direction, now nearly a quarter of a century ago, and in those early day he oft,en seemed a hard taskmaster—a man whose standards it woul never be possible for me to meet. I well recall his insisting upon m proving for the third time the truth of a conclusion which I had brc unwilling to submit to him until it had been confirmed by two carefull planned experiments. To my impatient protest that thc third .demor stration he asked for was but a repetition of the second, with differer samples, he replied, "Yes, that is true, but the inherent improbability ( your conclusions is so evident that I can not accept them until you prov your case again." "Shall I ever do a thing well enough to suit him? I thought. Looking back today upon many similar incidents, 1 suspect that h never expected me to attain the excellence he preached, and held up t me and to himself as a model, but knew out of the fullness of his experienc. that in no other way could he so impress upon me the necessity in researc of the patient, never-failing attention to detail and to accuracy tha distinguished his own work. How painstaking he was in the preparation of his many books an professional papers, as well as in his experimcntal work, was ncvcr s

Jan 1, 1929

By Richard W. Bayley

The Atlantic City district encompasses several districts and has been previously called by different names, e.g., Atlantic gold district, Atlantic City-South Pass mining district, and Sweetwater mining district. The district is located in a terrane of folded and faulted early Precambrian metamorphic rocks which lies near the south end of the Wind River Range in Fremont County, Wyoming, Historically it is a gold district of little production, but today is an iron district of considerable importance. Gold was discovered in placer deposits about 1842 and in quartz-arsenopyrite veins about 1867, after which there occurred a mining boom lasting a few years. Minor, intermittent gold production from placers and lodes has continued to date, but the total production has probably not exceeded a few millions of dollars. Past lode mining was generally shallow ( in the oxidized zone), the deepest about 3 60 feet. The deeper, less oxidized and sulfide ores on the same lodes have not been explored. They appear to hold the only hope for future gold mining. Sedimentary iron-formation, similar to the Lake Superior taconite, occurs in the northern part of the district. Locally, where the ironformation is thickened by folds and faults, sufficient tonnages are present to be minable, as at Iron Mountain, where the U.S. Steel Corporation produces about 1.3 million tons of iron-ore pellets annually. Exploration of the iron deposits began in 1954, and the first ironore pellets were shipped to Provo, Utah in August 1962. Indicated reserves of iron-formation (about 30 per cent Fe) are reported to be about 300 million tons.

Jan 1, 1968

By H. H. Hausner, H. S. Kalish

IN recent years zirconium and beryllium have become of great interest because of their special properties. Zirconium is known for its remarkable ability to absorb the gases oxygen, nitrogen and hydrogen, has extensive use as a getter in electron tubes and has indeed become the primary metal in the manufacture of photoflash bulbs. Beryllium is of interest because it is light metal and as such could supplement aluminum and magnesium in light metal applications. The late development of zirconium ductile at room temperature produced by both the iodide and calcium reduction methods has stimulated frequent articles on this metal in the recent literature. Beryllium is so closely akin to zirconium crystall-ographically that some investigators are of the opinion that beryllium should be ductile at room temperature if it were pure enough. The crystallographic relationship of beryllium and zirconium, the interest created in Be-Zr alloys where the zirconium is believed to function as a remover of solid solution gas in beryllium and thus increase the ductility of the beryllium rich alloy, and the amenability of these metals to powder metallurgy methods stimulated this approach to an investigation of the system Be-Zr. Preliminary work showed that a zirconium compact melted when pressed in contact with a beryllium compact and sintered at 1250°C, without any apparent final bond between the two. A search of the literature revealed nothing pertinent about the Zr-Be system or about any zirconium - beryllium alloys. In 1936 Misch³ vaguely identified the compound ZrBe2 and reported that it has a deformed cubic structure. Two patents," , were issued to Mach-lett Laboratories in 1943 and in 1946 regarding the addition of small amounts of zirconium to beryllium in order to improve the ductility of beryllium so that it may better be used for X ray windows. In considering the alloy formation of beryllium with other metals Raynor thought it unlikely that zirconium would have any solid solubility in beryllium. From this indefinite information nothing could be ascertained about the possible use of Zr-Be alloys or the use of these metals intimately. A brief preliminary study of the system Zr-Be by powder metallurgy methods was undertaken to provide regions for more intense studies of Zr-Be alloys and as a guide to a formal phase diagram determination. The investigation described in the following pages was completed in less than three weeks. The usefulness of this rapid method to facilitate phase diagram studies and new alloy investigations will be shown. Materials and Procedure Zirconium powder was produced from crystal bar stock of high purity supplied by Foote Mineral Co. The crystal bar was converted to hydride at 730°C, crushed, and the hydride decomposed in purified argon at 850°C. 60 pct of the powder passed through a 325 mesh screen, 40 pct of the powder was —140 mesh, +325 mesh and the average particle size of the total was 8 to 12 microns. The beryllium powder was used as re-

Jan 1, 1951

By R. E. Cuthbertson

AN early appreciation by the management that Climax ore presented a challenging problem of economic concentration was responsible for the establishment, in June 1926, of an ore-testing department at the experimental plant of the Colorado School of Mines at Golden, some ninety miles from Climax. An engineering office was later organized in the same community for the design of all ore-treatment units erected at Climax during the period of rapid growth. Work of the ore-testing and design staffs was effectively co-ordinated under a common head. The primary reason for having the ore-testing and plant design departments in Golden, was to place these activities under the able supervision of A. J. Weinig, consultant for the Climax Molybdenum Co., and director of the experimental plant. A secondary consideration was the availability of excellent facilities for research in ore dressing in a highly favorable environment. Concentration of molybdenite by flotation from an ore of simple mineral composition does not appear, superficially, to present a serious problem in ore dressing but experience belies this apparent simplicity. The molybdenite content of average Climax ore is low and it is finely

Jan 1, 1946

By Frederic E. Carter

THERE have been many attempts to prove that platinum was known to the ancients, but since no traces of the metal have been found in the relics of early times, it must be concluded that it was not known to them. As far as records go, it was actually first discovered in the 16th century in a Spanish mine on the Pinto River in South America; from which source it received its name of Platina del Pinto (little silver from the Pinto). It was more or less of a rarity and was a subject of interest to a few chemists only, until the year 1822 when the metal was first discovered in Russia. In 1819 there were noticed in the washings of the gold sands of the southern part of the Ural Mountains, grains of a heavy white substance, but it was not until three years later that this substance was found to contain platinum. While at first the amounts of platinum brought from the Urals were meager, prospecting soon disclosed rich deposits extending over a considerable area, and nuggets from 10 to 20 lb. were by no means rare. This discovery assured to chemists an ample supply of platinum for their crucibles, etc. The ore is now found in various parts of the world but the richest deposits are still found in the Ural Mountains. The platinum of commerce is obtained entirely from alluvial deposits at depths varying from 6 to 40 ft. The sand and gravel of former river beds are subjected to a series of screenings and washings to effect the separation of the ore. Actually, probably all gold-bearing gravel beds of the world contain platinum, and it is more than likely that large quantities of platinum ore have been thrown away with the black sand washings from gold placer deposits. This is especially true of the alluvial deposits of the Pacific Coast in California and Oregon. Platinum ore is usually found in the form of rounded or flattened grains of "sand," and occasionally in irregular lumps of the size of peas. Large nuggets are very rare. The ore has a metallic luster and is distinguished by its steel gray color, but shows light gray streak when rubbed on a hard white surface; it has a high specific gravity, 16 to 19; is infusible in the hottest blast furnaces, and insoluble in any single acid. Platinum ore is a complex body consisting of the metal in combination with varying proportions of the other members of the platinum group; iridium,

Jan 1, 1928

By H. T. Hildage

Although Greater New York does not bear any resemblance to a great mining district, the mining operations that are being conducted in and about the city are both extensive and interesting in character. With regard to the extent, it may be mentioned that, at present, there is more dynamite used in New York than in any mining district in the United States; that there are under construction about 38 miles of tunnel, and that 66 miles more are projected, most of which must be constructed .in the near future; that since 1903 at least 2,000,000 tons of earth has been removed in underground work, in addition to about 3,500,000 tons that has been removed in open-cut in connection with tunnel-work, and many times this quantity that has been removed in excavating foundations for buildings not connected with tunnel-work; and that there are to-day probably more than 5,000 men engaged in mining-work in and about New lrork City. These undertakings include almost every operation connected with underground work, from exploration by means of trench and boring, to the sinking of large shafts and the driving of large tunnels through every kind of ground from hard rock to soft, semi-fluid silt and quicksand. It is proposed in this paper to give a general description of some of the methods and appliances used in the opening-up of a " mine " in a large city, and a brief description of some of the &'mines" now being developed in New York, connecting as far as possible the methods described with the particular work for which they were designed, in order to give a general idea of the

Jan 1, 1908