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By Douglas J. Robinson

A pilot scale process has been developed to separate mercury, tin, silver, and copper from dental amalgam scrap. Laboratory research led to a process which was operated in 55 gallon drum sized reactors to treat 2000 Tr oz charges of scrap per day. This paper discusses the development work, presents a flowsheet and gives an indication of the equipment necessary to carry out the process on a commercial scale.

Jan 1, 1984

By W. R. Ingalls

WHAT proportion of the national wealth is represented by' the producing mines of the country?' Or by the- mining and metallurgical industry-as a whole, for it is impossible to make-an economic distinction between the mines that produce the ore and the plant that is used to get the metals from it. The total national wealth in fixed property is about $270,000,000,000. How much for the mines? I do not know that any one 'else has ever tried to furnish answers to these questions. In making such an attempt I am conscious that the result can be nothing more than a rough approximation. Yet even that will give an idea of relative values. No separate valuation for the mines of the country has appeared in any inventory of the national wealth previous to that which I compiled and published for 1916. -In earlier census estimates mines were supposed to be included under the head of real estate. However, an examination of the laws and practices of the several states with respect to mine taxation will make it evident that no good idea of the value of the mines of the coun¬try is obtainable from the assessment rolls. In my previous estimate for 1916, I computed the value of the mines at $8,000,000,000, which was approxi¬mately 10 times their net income as reported to the Bureau of Internal Revenue. In making that estimate I fell grossly into error, for several reasons that it is unnecessary to explain, but chiefly because the net income of the mines of the country in that year was exceptionally large. The whole subject of valuing the mines of the country en bloc is extraordinarily difficult At the best, no one can hope to arrive at, anything more than a rough idea about it. However, elements of reason may be introduced and may be made to serve as chief bases.

Jan 1, 1921

By Milton C. Head, Aulton E. Roland, William E. Hawes

INTRODUCTION Uranium mining in the Grants Mineral Belt has undergone changes from methods pioneered during the 1950's and has now become fairly standardized throughout the district. The orebodies vary in size and shape and have been most successfully mined by using modified room and pillar methods with pillar recovery. This paper will expand on methods and equipment that are being used and modifications of these that will increase productivity and efficiency. GEOLOGICAL BACKGROUND The petrology of the Grants Mineral Belt consists of alternating layers of sandstone and shales (mudstone), with occasional thin layers of coal. The sandstones are aquifers which are generally artesian to some extent. The shales are bentonitic and decompose into extremely sloppy mud when exposed to water. Figure 1 shows a typical geologic section. Most of the uranium produced in the Grants Mineral Belt comes from the Westwater Canyon member of the Morrison Formation and occurs as scattered ore bodies throughout the formation. This formation consists of layers of bentonitic shale and sandstone of varying degrees' of cementing and grain size. It is also a very significant artesian aquifer. The unconfined compressive strength of the various formations is not high, as shown in Table I. It is important to note that these represent average values and a great range may exist within a single formation, especially In the Westwater which is the ore formation. [ ]

Jan 1, 1982

COMPARED with the equipment used in most industrial processes, the open-hearth furnace has a relatively short life. The most important quality of an open-hearth refractory, therefore, is its rate of failure. This discussion of the physics and chemistry of the individual refractory materials will keep upper- most the question "Why, how, and where does it fail?" CAUSES OF FAILURE The principal causes of failure of open-hearth refractories are, in their order of importance: 1.Reaction with iron oxides. 2. Reaction with slag. 3. Flow and failure under load. 4. Melting. 5. Spalling. 6. Mechanical breakage. Reaction with Iron Oxides and Slag. Reaction with iron oxides and slag is by far the most important cause of failure. Liquid iron oxide comes near to being the "universal solvent" sought for by the alchemists. Among the materials commonly used in the open-hearth furnace, magnesia has the greatest resistance to this liquid and fireclay the least. The relations of iron and oxygen at high temperatures are illustrated in Fig 14-18. The liquid iron oxide that forms wherever iron is in contact with air or combustion gases cannot be given a definite formula. The percentage of oxygen at steelmaking temperatures may range from 21 to 28 (iron 79 to 72), depending upon the temperature and the oxygen pressure and also upon whether or not the liquid is in equilibrium with metallic iron. Oxide mixtures exist not only in the solid and liquid phases but also in the vapor phase, for metallic iron and its oxides have

Jan 1, 1951

THE object of all classification is to group together things which are alike, and separate those which are unlike. This object is essentially a practical one, enabling us to apply past experience to new conditions: Many costly large-scale experiments lose half their importance for want of proper description of the coal used, and the consequent impossibility of predicting other coals will behave in the same way. I do not, therefore, make a fundamental distinction between "scientific" and "use" classifications, except in so far as use depends on conditions, such as size or impurities which are not related to the nature of the coal substance itself. The characters chosen to define the classes of coal must be such as are accompanied by as many other properties as possible. It is not to be expected that any system of classification will enable us to predict every property of coal, since all specimens have an individuality of their own. But specimens can be grouped by a number of resemblances into species. Further, species which resemble each other can be grouped into genera.

Jan 1, 1928

By Eric Jette

THE results of an investigation of the ternary system iron-chromium-ilicon were reported in 1936 by the present authors.1 Partly for the sake of theoretical interest, and partly because of the possible commercial importance of these alloys, the present investigation was undertaken to determine the effect of some of the commoner elements likely to occur, deliberately or otherwise, in such alloys if made on a commercial scale. The elements thus added were carbon, nickel or manganese. The alloys studied were, therefore, parts of quaternary systems. This investigation was concerned primarily with the effect of these additional elements on .the alpha-iron phase and the boundary between this phase region and the alpha plus sigma two-phase region. The sigma phase is a ternary solid solution based upon the compound FeCr. The work was performed mainly by X-ray methods, but a number of microscopic examinations were also made and are reported. While isolated alloys in the composition ranges studied may have been discussed in metallurgical publications, no systematic investigation of any assistance to us was found. Of the earlier work, the investigations on the iron-chromium-carbon system and on the chromium carbides by Westgren and his coworkers,2,3 enabled us to identify the carbide phase. Several articles appeared after the present experimental work had been completed. Lucas and Wintrup4 determined the solubility of carbon ill molten iron-chromium-silicon alloys. Tofaute and his coworkers5,6 have made detailed studies of the iron-chromium-carbon system, which will he referred to later.

Jan 1, 1937

By S. E. Bronisz, J. O. Brittain

Experiments have been carried out to study the effect of an applied stress on strain aging in steel. It was found that the stress-induced strain aging reaction proceeds rapidly in the temperature range of 0° to 60°C. The variation of stress-induced strain aging with plastic strain, aging time, and temperatures is reported. The activation energy for the stress-induced strain aging was found to be 10,000 cal per mol for the steel used in this investigation. VARIOUS observations1-5 have been made of the influence of an applied stress upon the yielding of iron and steel. However, there have been only cursory studies of the effect of an applied tensile stress upon strain aging in iron and steel1,2 The following represents the results of a preliminary study of strain aging as influenced by the application of an external tensile load during the aging process. For the most part, previous experimental work on strain aging can be classified into two parts. First, the experimental technique involved a direct determination of mechanical properties of a suitable specimen that has been plastically deformed to a constant strain and aged generally at a temperature of the order of 200°C, with the aging times varying from about 1/10 to 2 hr.6-8 The second classification of strain aging experiments involves an indirect determination of strain aging by means of physical property such as electrical resistivity or internal friction as a function of the aging time at a constant temperature and strain.9-12 The latter results have

Jan 1, 1961

SEC 1 The membership of the Institute shall comprise seven classes, namely 1 Members, 2 Honorary Members, 3 Senior Members, 4 Associates, 5 Junior Members, 6 Rocky Mountain Members, 7 Junior Foreign Affiliates All shall be equally entitled to the privileges of membership, excepting that no member of any class whose residence shall be outside of the United States of America, except those residing in Mexico and Canada, shall be entitled to vote SEC 2 Members A person to be eligible for election or transfer into the class of Member must be at least 27 years of age and must have had at least six years' employment in the practice of engineering, mining, geology, metallurgy, or chemistry, during at least three years of which he must have held positions of responsibility in one or more of these fields This shall not apply to Rocky Mountain Members SEC 3 Honorary Members Each candidate for Honorary Membership must be recommended by the Committee on Honorary Memberships and must be elected by ballot at a meeting of the Board of Directors by the unanimous vote of the Directors present, provided, however, that the number of Honorary Members shall at no time exceed twenty Such election shall automatically act as a transfer of such member from any other class of membership to which he may belong SEC 4 Senior Members The Directors may, at the special request of any Member or Associate who has reached the age of seventy years and who has paid

Jan 1, 1952

By R. L. Andelin, J. D. Knight, M. Kahn

Self-diffusion in single-crystal tungsten and diffusion of rhenium tracer in single-crystal tungsten have been measured over the temperature range 2660° to 3230°C by direct sectioning and radio-chemical analysis of W185 and Re183 and Re184 tracers. The initial radioactive layer was produced on the diffusion specimens by bombardment with 9.0-mev deuterons. Diffusion heating of the samples in high vacuum was accomplished by induction heating. Temperatures were measured by optical pyrometry, and the system was calibrated ALTHOUGH a considerable body of experimental information has been accumulated on self-diffusion in solids, the major part of the detailed work has by reference to the melting points of tantalum (2996°C), molybdenum (2620°C), niobium (2468°C), and rhodium (1966°C). The diffusion coefficients for the two systems, obtained by least-squares analyses of the data, are well-represented by the equations thus far dealt with relatively low-melting systems. Diffusion studies on the high-melting elements niobium,1 tantalum,2,3 and tungsten4'5 have been limited to polycrystalline material, for which data interpretation and theoretical analysis are sometimes difficult. Only recently, a study has been made with single-crystal molybdenum.6 The present work deals with the measurement of self-diffusion in single-crystal tungsten at temperatures approaching the melting point (3410°c).7 Since the method chosen for producing the radioactive tracer layer-bombardment with deuterons—produced detectable isotopes of rhenium as well as of tungsten, the diffusion of rhenium was measured also.

Jan 1, 1965

By E. Miller, J. M. Eldridge, K. L. Komarek

The liquidus curve of the Mg-Pb system was accurately redetermined. The compound Mg2Pb decomposes peritectically at 538.2° ± 0.3°C to liquid and to a compound p' which melts congruently at 35.0 at. pct Pb and 549.0° ± 0.3°C. The solidus curve of ß' was determined. X-ray diffraction studies indicate that 4' has an orthorhombic structure. Activity values of magnesium calculated from the phase diagram agree with those published in the literature. EXPERIMENTAL thermodynamic properties of binary metallic systems have to be consistent with values calculated from the phase diagram. In systems forming intermetallic compounds the shape of the liquidus curve near a compound is determined by the thermodynamic properties of the coexisting solid and liquid phases. Hauffe and Wagner' neglected the temperature dependence of the chemical potentials and obtained the potential differences of the components of the liquid alloys, relative to stoichiometric liquid. Their calculations were based on the liquidus curve and on the heat of fusion of the compound, and were only valid near the congruent melting point. Steiner, Miller, and Komarek2 developed equations which account for the temperature dependence and obtained the chemical potentials of liquid Mg-Sn alloys over the entire phase diagram from the liquidus and solidus curves and from enthalpy values with the pure components as the standard states. The Mg-Pb phase diagram has been studied by several investigators whose results have been compiled and critically evaluated by Hansen.3 Although the liquidus curve was poorly defined, the general features of the diagram, i.e., one congruent melting compound, Mg2Pb, of essentially stoichiometric composition, two eutectics, and limited terminal solid solubilities, seemed to be suitable for a similar thermodynamic analysis. A careful redeter-mination of the liquidus by thermal analysis revealed, however, the existence of another compound. The liquidus curve between the two eutectics was precisely delineated and the structure and solidus curve of the new compound were investigated. The revised phase diagram was thermodynamic ally analyzed to evaluate the activity of magnesium in the liquid alloys. EXPERIMENTAL PROCEDURE The magnesium metal (Dominion Magnesium Ltd., Toronto, Canada) had a purity of 99.99+ pct; lead (American Smelting and Refining Co.) contained 99.999 pct Pb. Most experiments were carried out in graphite crucibles. Several experiments were made in high-purity alumina (Triangle R.R., Mor-ganite, Inc.) and in Armco iron crucibles to test the inertness of the graphite crucibles. Chemical analysis of magnesium and detailed description of the procedure for thermal analysis have been given previously. For the determination of the solidus curve of the compounds, specimens of initial composition Mg2Pb were equilibrated in a closed isothermal system with magnesium vapor. The source of the magnesium vapor was an alloy which had a gross composition lying in the 0' + L field at the temperature of equilibration. As equilibrium was approached, the specimens lost magnesium to the two-phase reservoir thereby lowering the activity of magnesium in the specimens until activity and composition equaled that of the ß'/ß' + L boundary. Crucibles (1.9 cm ID by 2.2 cm OD by 4.1 cm high) and tightly fitting lids were machined from a molybdenum rod; small, shallow trays were fashioned from thin (0.005 in.) molybdenum sheet, and all the molybdenum components were degreased in hot carbon tetrachloride and then dried. The pieces were then degassed in vacuum at 950°C for about 6 hr. The two-phase alloy was placed at the bottom of the crucible and small specimens of the Mg2Pb compound, weighed on an analytical balance, were placed in two molybdenum trays above the two-phase alloy. The crucible was closed by forcing its lid on and then inserted in a titanium crucible. This crucible was evacuated, flushed twice with argon, and welded under argon. The specimens were equilibrated for about 1 week in a resistance furnace regulated by a Celectray controller, and the runs were terminated by water quenching. The specimens were again weighed and the equilibrium compositions were calculated on the basis that the weight losses were solely due to a loss of magnesium to the two-phase alloy. The structure of the B' phase was investigated by the Debye-Scherrer X-ray diffraction technique. Selected ingots from thermal-analysis experiments containing about 35 at. pct Pb were re-melted, slowly cooled, and crushed in an argon-filled glovebox until the entire ingot passed through a 50-mesh sieve. The powder was thoroughly

Jan 1, 1965

Jan 1, 1970

By B. Ladanyi, B. Hoyaux

A first requirement for assessing the safety of a rock slope, either artificial or natural, particularly if the rock behaves in an elastic-brittle manner, is a propw knowledge of the distribution of stresses within the slope and their development with time and advancement of workings. There are a uumber of different methods that can be used, in principle, for obtaining this information, such as (1) stress measurement in situ, (2) photoelasticity,1 (3) analytical methods, and (4) numerical methods. In cases where the stress distribution cannot be obtained by classical analytical methods, as in the one considered herein, either photoelasticity or numerical methods are norrnally used. However, actually, due to the rapid development of high-speed computers, increasing preference is given to the numerical methods. Among the latter, the most successful ones, to date, for determining the stress distribution in slopes have been (1) the finite difference method,2-4 (2) the lumped parameter method,5 and (3) the finite element rnethod.6 However, for determining gravity stresses in a natural rock slope, only the finite difference method has been used until now.7,8 A solution of the same problem by the finite element method will be shown here in which a particular reference is given to the development of tensile fracture zones within the slope. FINITE ELEMENT METHOD The stress analysis using the finite element method originates from an extension of the matrix analysis of structures.9 It consists in decomposing a continuous medium, assumed herein to be homogeneous and isotropic,

Jan 1, 1972

By Maynard O. Serbousek, James R. McVey

IS there a quick way of assessing the conditions of a newly exposed roof in a coal mine? This has always been a nagging question. The problem is that unless effective controls are established as soon as possible, it becomes extremely difficult to extract coal safely and economically from conventional underground milling operations. Until recently, little has been done to provide a means of measuring the structural behavior of a coal mine roof while the face advances during actual production. (In fact, most measurements have always been made after the fact or during a roof pull-down where the roof is actually caused to fail with no support.)

Jan 9, 1976

By Captain Lyle

I was very much interested in Mr. Macdonald's paper, and I can say that there is nothing in it to which I cannot heartily subscribe. In speaking of the want of knowledge that has existed, and still exists, among engineers in regard to structural materials, their strength, etc., my own experience has taught me to doubt the reliability of the ordinary testing machines.

Jan 1, 1882

By Basil B. Zavoico

Production of crude oil in the U. S. S. R. during 1939 is estimated at, 226,111,000 bbl., as compared with 219,778,000 bbl. in 1938, an irlcreasc of 2.88 per cent but some 6.00 per cent under the planned output. During the past year a major readjustment took place in Russian oil fields, with the Grozny district falling into the third place, its former place having been taken by the fields of the Maikop-Kuban area of northwestern Caucasus. Production continued to grow in the Ural-Volg:t district and further large increases in this province in the coming years are certain. The drilling operations continued to be most unsatisfactory, falling far behind the plan, possibly as much as 25 per cent undvr the set objectives, and thereby interfering with the production plans, mora particularly since the Soviet oil industry is still based primarily upon the production from the naturally flowing wells without any proration whatsoever rather than upon stabilized production from either prorated oil wells or those operated with various mechanical lifts. The year 1939 started with the fulfillment of the drilling programs to the extent of about 90 per cent, but the situation rapidly deteriorated arid by the second half drilling programs were being fulfilled only to the extent of 60 per cent or less. Such breakdown in drilling operations was possibly due to poor equipment, which has not been able to stand increasing demands upon it, and this is substantiated by the rccent orders plaeed in the United States by the Soviet Government for some 60 drilling rigs of the latest design. Production Baku District.—-The fields of the Apshcbron Peninsula (Baku district) made a notable progrress during the past year and were able slightly to increase their production, to 166,000,000 bbt. as compared with 164,692,-000 bbl. during 1938. The c.rnphasis of production in the Baku district remained on the flowing wells, about 20 per cent of the total number of wells flowing about 70 per cent of production. During 1939 some 550 wells were complr.tcd in the Baku district with active rigs averaging

Jan 1, 1940

By Basil B. Zavoico

Production of crude oil in the U. S. S. R. during 1939 is estimated at, 226,111,000 bbl., as compared with 219,778,000 bbl. in 1938, an irlcreasc of 2.88 per cent but some 6.00 per cent under the planned output. During the past year a major readjustment took place in Russian oil fields, with the Grozny district falling into the third place, its former place having been taken by the fields of the Maikop-Kuban area of northwestern Caucasus. Production continued to grow in the Ural-Volg:t district and further large increases in this province in the coming years are certain. The drilling operations continued to be most unsatisfactory, falling far behind the plan, possibly as much as 25 per cent undvr the set objectives, and thereby interfering with the production plans, mora particularly since the Soviet oil industry is still based primarily upon the production from the naturally flowing wells without any proration whatsoever rather than upon stabilized production from either prorated oil wells or those operated with various mechanical lifts. The year 1939 started with the fulfillment of the drilling programs to the extent of about 90 per cent, but the situation rapidly deteriorated arid by the second half drilling programs were being fulfilled only to the extent of 60 per cent or less. Such breakdown in drilling operations was possibly due to poor equipment, which has not been able to stand increasing demands upon it, and this is substantiated by the rccent orders plaeed in the United States by the Soviet Government for some 60 drilling rigs of the latest design. Production Baku District.—-The fields of the Apshcbron Peninsula (Baku district) made a notable progrress during the past year and were able slightly to increase their production, to 166,000,000 bbt. as compared with 164,692,-000 bbl. during 1938. The c.rnphasis of production in the Baku district remained on the flowing wells, about 20 per cent of the total number of wells flowing about 70 per cent of production. During 1939 some 550 wells were complr.tcd in the Baku district with active rigs averaging

Jan 1, 1940

By AIME AIME

OUT of the fabulous iron ranges of Michigan?s Upper Peninsula since Pearl Harbor have come go to the steel mills to become tanks, guns, ships, and other weapons for a United Nations' victory. But the contributions to the war effort, as far as Michigan's iron country is concerned, do not stop there. The same men who mine iron ore deep inside the earth also are "mining" on top of the ground, gleaning a harvest of scrap iron and steel that is writing a big chapter in the War Production Board's salvage program. At virtually every mine over an area of a hundred square miles, everyone from the top mine official and straw boss to the man in the dippings is scrap conscious. They know the importance of the ore they mine but they are equally familiar with the importance of iron and steel scrap in war production. The successful job they are doing in salvage is a tribute to the entire Upper Michigan mining industry and to the man who marshaled them into action-John M. Bush, chief of the land department for the Cleveland- Cliffs Iron Co. at Negaunee, and for ten years an A.I.M.E. member. Also, this job should be an inspiration to 611 mining. metallurgical, and petroleum communities as to the latent possibilities of organized scrap recovery.

Jan 1, 1943

By N. A. Ziegler

A CERTAIN amount of interest has been indicated recently in the resistance to oxidation at high temperatures of iron-aluminum alloys (rich in iron). Hautman1 published a paper in. which some interesting results are given. According to his paper, only alloys containing at least 8 per cent aluminum indicate a marked improvement in their resistance to oxidation. At about this aluminum content, however, alloys become brittle, which considerably reduces their commercial value. About two years ago the author, performed a series of experiments, the results of which are presented here. A series of iron-aluminum-carbon alloys was prepared by melting electrolytic iron, aluminum and high-carbon iron alloy in an induction vacuum furnace.2 The list of these alloys is given in Table 1. Each alloy was forged in the ordinary way to

Jan 1, 1932

By R. D. Pehlke, W. M. Small

The effect of added alloying elements on the solubility of nitrogen in a liquid alloy of 74 wt pct Fe. 18 wt pct Cr, and 8 wt pct Ni has been studied. At 1600°C and 1 atm nitrogen pressure, aluminum, chromium, columbium, manganese, molybdenum, tantalum, and vanadium increase the solubility of nitrogen in the liquid 18 Cr-8 Ni alloy, whereas additions of cobalt, copper, nickel, silicon, tin, and tungsten decrease the solubility. Interaction parameters based on a constant ratio of iron, chromium , and nickel have been used to quantitatively define the changes in nitrogen solubility. INVESTIGATIONS on the solubility of nitrogen in liquid iron have usually treated the pure metal, and often the influence of a single added element. Pehlke and Elliott1 carried out a comprehensive study on the influence of alloying elements on nitrogen solubility in liquid iron, and compared their results with previous studies. Turnock and pehlke2 have recently reported a study on the solubility of nitrogen in multicomponent liquid iron alloys. The original interaction parameter proposed by wagner3 was successfully employed in these studies. The need for obtaining information on the gas solubility in more complex alloys is indicated by the increasingly significant role played by dissolved gases in the processing of iron-based materials. The commercial stainless steels, for example, represent an area where data on nitrogen solubilities are required as a function of composition, temperature, and gas pressure. The nitrogen solubility in liquid Fe-Cr-Ni alloys has been studied by Humbert and Elliott.4 Their investigation covered the entire ternary system, and attempted to use data from binary alloys to predict nitrogen contents in liquid ternary alloys. Langenberg,5 using a method developed by Morris and buehl,6 calculated the nitrogen solubilities in multicomponent iron alloys from data available on binary iron alloys at 1600°C. Nelson,7 using a regular-solution model, extended this prediction to include the effect of temperature. Chipman and corrigan8 and Turnock and pehlke2 also employed empirical methods to calculate nitrogen solubilities in liquid multicomponent iron alloys. In order to provide a basis for predicting nitrogen solubility in liquid stainless steels, and to extend the data available for thermochemically modeling systems of this type, the following investigation was carried out. The study involved measupements of nitrogen solubility in a nondilute alloy and examination of the influence of a small addition of an alloying element on the nitrogen solubility. The study was focused on a very narrow range Of composition in the vicinity of 18 wt pct Cr-8 wt pct Ni (herein referred to as 18-8) with special emphasis on the change of.nitrogen solubility with the addition of a fourth metallic element. EXPERIMENTAL PROCEDURE A Sieverts' apparatus, described previously,1,2 was used in this investigation. The charge materials were contained in a recrystallized alumina crucible and inductively melted. Additions were dropped from a glass side-arm. All materials were hydrogen-refined and vacuum-treated to eliminate or minimize the oxygen content. The source and purity of materials is given in Table I. The initial metallic charge was heated to approximately 1000°C and held under vacuum for 30 to 45 min as a means for removing hydrogen and adsorbed gases. Argon was used as the calibrating gas to determine the "hot volume". The average hot volume of the system was approximately 50 cu cm STP and a few experimental runs were made using a reaction bulb with a hot volume of 80 cu cm. The temperature range studied was from 1550° to 1700°C and the temperature was measured optically. THEORETICAL PRINCIPLES General Discussion. Nitrogen dissolves in liquid iron alloys according to the reaction: 1/2N2(g) = N (wt pct in solution) [l] The equilibrium constant, K1, for this reaction is written as:

Jan 1, 1969

By Walter B. Devereux

Metallic copper is a product of native metallurgy in various parts of Mexico, and by somewhat varied processes. While recently examining copper mines in the State of Jalisko, I had an opportunity of witnessing Mexican copper smelting by a process which I have not seen described, and which is interesting from the fact, that a fine quality of copper is produced from sulphurous ores in three metallurgical operations, and apparently without excessive loss. The process was carried on in buildings which were part of a plant erected by an American more than twenty-five years ago for the purpose of smelting and working copper. After a few years this man met with accidental death, and the works have been but little used since. Located in the centre of a high range of mountains, far from any town or seaport, and inaccessible except over difficult mule trails, these substantial buildings, filled with furnaces and heavy machinery,

Jan 1, 1883