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By John J. Croston

IN the closing months of 1936 the copper industry gave every evidence that it was at last on the threshold of an improved era. At the beginning of the year prices stood at 9 ¼ ¢, which in itself was a great improvement over prices prevailing for the three previous years. Industry generally was showing signs of moving forward in this country, and business was definitely good in certain foreign quarters. The threat of war and preparations for rearmament in Europe and Asia acted as a further stimulus to purchasing. By midsummer the situation had so improved and stocks had been so reduced that the cartel of foreign producers (including American producers with foreign mines) decided to increase the production quota to 75 per cent on Aug. 1. Large-scale buying gave continued strength to the price and by Oct. 1 the quota was increased to 80 per cent, and again on Oct. 15, to 85 per cent. Notwithstanding this the price of copper continued its advance and on Nov. 1, with stocks declining continuously, the cartel increased operations to 95 per cent, then to 105 per cent on Nov. 5. In the meantime the domestic producers, because of the great increase in home consumption, had increased their production by nearly one-half. At the close of the year copper sold at 12¢ per pound, and since the turn of the present year has reached 17¢. This rapid increase has not been wholly justified. Much of the increase was due to the legitimate demands of recovering industry, but rearmament orders plus accumulation of reserve stocks in case of war, purchases in anticipation of labor strikes and purely speculative activities on the London Metal Exchange accounted for the balance. Certainly in view of the state of industry and the general world price level, it appears unnecessarily high. Talk of a copper shortage is sheer nonsense, the recent condition in the market being created by overbuying, leaving but a small volume for speculative supplies. It takes some months for an increase in mine output to reach the market, but production is again overtaking apparent consumption, stocks have begun to increase, and this, together with the reopening of many small

Jan 1, 1937

By Dr. O’Neil Thomas J., Donald W. Gentry

"We should be concerned about the future be- cause we will have to spend the rest of our lives there. " -Charles Kettering INTRODUCTION Since the early 1970s, there has been no economic phenomenon that has been more widely discussed or experienced in the United States than inflation. Al- though its precise definition and measurement are elusive, inflation has had pro- found and extensive impacts on the manner in which nearly everyone lives. It is painfully obvious to consumers that inflation is characterized by a continuing up- ward spiral of prices. In a capital-intensive industry like mining, those increases can be positively breathtaking. An interesting example is shown in Table 1. Table I shows that on a unit basis, the equivalent 1980 capital cost of Cuajone was over six times the cost of the adjacent and quite similar Toquepala operation completed in 1959. Such sobering statistics weigh heavily on the minds of executives who are contemplating major investments in new mining facilities. In spite of its monumental presence, inflation has usually been either inadequately covered or totally ignored in textbooks on engineering economy. The reasons for this are not entirely clear, but a contributing factor is the inherent difficulty in accurately predicting inflation. However, under certain conditions, inflation may become the most important factor in a mining investment, and it can rarely be safely ignored in capital investment analyses. DEFINING AND MEASURING INFLATION Defining inflation and related terms is relatively easy. Its measurement, how- ever, is the source of almost endless debate in economic and political circles. How- ever, much of that debate is not relevant to the scope of this book, so that only those issues which impact directly on the capital investment decision are covered in this section. Inflation is the general decline in the value of money as measured by what it will buy. It is clear, then, that the rate of inflation varies with the particular currency under consideration as well as the type of goods and services being purchased. One would find, for example, that the general rate of inflation relative to German marks

Jan 1, 1984

By W. A. Thomas

STEAM is, and doubtless always will be, the basic power in the anthracite industry, either directly applied through engines and pumps or electrically. The rapidity with which electric power is being applied to the mining and preparation of anthracite leaves little doubt as to its utility and economy. There is practically no operation, except possibly the drilling of hard rock, that has not been successfully electrified and the matter of drilling is handled economically with electrically driven compressors and the standard compressed-air drills. Conservation and the seemingly ever-increasing cost of production, justify careful consideration of the possible results of the more extensive use of electric power in the industry. It is not planned to discuss, herein, the relative economies of individual applications but to consider the relative economy and flexibility of steam and electric power. The reports available for the year 1920 indicate a production of slightly over 80,000,000 tons of anthracite, of which 8,843,500 tons were used for power and heating purposes; in other words, over 11 per cent. of the production was used at the mines. Some of this was used to generate electric power at the mines, about 160,000,000 kw-hr., while 150,000,000 kw.-hr. was purchased from the public utility companies. One large producer, who is buying some electric power and generating some, used over 13 per cent. of the production for power and heating at the mines. Another producer, where considerable electric power is generated on the properties, is using less than 9 per cent. of the output for power and heating. One of the largest producers has a fuel consumption of over 15 per cent. of the output, besides which considerable power is purchased. A careful study of the field indicates that steam-operated plants use upwards of 13 per cent. of the production for power and heating, while electrically operated plants use about 1 per cent. for heating; so that, for steam-power purposes at least 12 per cent., or 268.8 lb., are used for power out of each ton produced.

Jan 9, 1921

By George D. Graffin

The first use of graphite is lost in the mists of time. It was used by primitive man to make drawings on the walls of caves and by the Egyptians to decorate pottery. As early as 1400 A.D. graphite crucibles were being made in the Haffnerzell district of Bavaria. Through the Middle Ages graphite was confused with other minerals, especially galena and molybdenite. Two common names that are still used for the mineral are "Plumbago," meaning leadlike, and "Black Lead." The latter name implied that graphite is either composed of lead or at least contains a large percentage of it. Gessner is credited with having recognized it as a separate mineral in 1565, but its composition was not determined until 1779, when Scheele demonstrated that graphite oxidized to carbon dioxide, thus proving its carbon constitution. In 1789, Werner named it "graphite" from the Greek word "graphein," meaning to write. The United States has long relied on foreign countries for its graphite supplies. This reliance has been due more to the lack of suitable domestic graphites than to any particular preference for buying minerals overseas. Ceylon (now Sri Lanka) graphites were imported as early as 1820, and Madagascar graphites have been imported since the properties on that island were opened up about a hundred years later. Mexico has long supplied the United States with most of its requirements for amorphous graphite. Physical Properties and Classification Graphite is found in laminated, flaky aggregates disseminated in schistose rocks. It also occurs in veins and exhibits a foliated or fibrous structure. Graphite is a black lustrous mineral that crystallizes in the hexagonal system, with rhombohedral symmetry. The crystals have tabular form and are six-sided; the faces are commonly striated. The flakes have perfect basal cleavage and are opaque. When well crystallized, the flakes have a black metallic luster while the amorphous material is black and earthy, with a microcrystalline compactness. The flakes feel greasy. Graphite is an excellent conductor of heat and electricity. It melts at approximately 3500°C and sublimes at about 4500°C. It is combustible in the presence of oxygen between 620° and 670°C, but is stable and chemically inert at ordinary temperatures.

Jan 1, 1975

By Richard Moldenke

So FAR as the quality of the product is concerned, the history of the production of pig iron for foundry purposes is one of constant retrogression. The steps in this deterioration began with cold-blast charcoal pig iron, then anthracite iron, coke iron; then gradually warm to hot-blast coke iron, with the charcoal furnaces also heating their blast to get greater tonnages, and finally the present day hot-blast coke irons with scrap additions to the ordinary burden that, according to one European report, have gone as high as 135 per cent. Parallel with this quality retrogression is the enormous increase in furnace tonnages from about 15 tons daily to over 1000 tons per day in exceptional instances of modern practice. The key to this situation is economic pressure. The effect is a growing differentiation between furnace production for gray iron and malleable foundries and for the production of commercial steel. As the foundry is often compelled to draw upon the pig irons made for steel purposes, for economic reasons, whereas the steel industry does not draw upon foundry pig irons proper, the situation is resolving itself into one of grave consequence for the life of the gray-iron castings industry, and hence the intensive present-day feeling in foundry circles for rigid specifications to govern the quality of pig irons sold for foundry use. In the discussion of a paper on the use of scrap in the blast furnace held recently in the Institute, a very pertinent remark was made by one of the participating furnacemen, who confessed that "the things found wrong by the foundryman with his iron were beyond his depth." It may be added that those things are also beyond the depth of most foundrymen who, however, know from their results that they are getting poorer castings today with many pig irons than they did with those same brands in former years. Under the former fracture buying, the foundryman at least could select the strongest metal, as judged by the sledge, from various brands of similar fracture and pig section, and his results proved the soundness of his conclusions. With the advent of iron analysis, and in spite of the growing uniformity of the metal through greater tonnage

Jan 2, 1927

By C. A. Herbert

WITHIN the past few years, considerable development has been made in the coal-mining industry in Illinois and Indiana and it is the purpose of the authors to record its most important phases. Perhaps the two most striking features are the entry into the producing fields of certain large consumers of coal and the magnitude of some of the new operations. Mines are now being equipped by the. Chicago & Northwestern R. R., the Chicago,. Burlington & Quincy R. R., the Standard Oil Co., of Indiana, and the Union Electric Light & Power Co. of St. Louis. Besides, the U. S. Steel Corpn. has increased its coal-mining activities by commencing operations on its large holdings northeast of Benton, Franklin Co., Ill. Until recent years, the supply of coal has commonly been adequate and prices have generally been favorable, especially to large consumers, as the magnitude of their purchases enabled them to obtain satisfactory quotations from producers. In fact, most consumers of coal have believed that they could buy their fuel more satisfactorily in the open market than they could produce it themselves. The entry of the United States into the war was accompanied by various disarrangements of industrial conditions, and a demand for coal in excess of the supply seemed likely to be experienced for an indefinite period. Under these circumstances it seemed that the greatest assurance of a supply of fuel was its production by the operation of mines. In the case of the Chicago & Northwestern R. R. and the U. S. Steel Corpn. the production of coal has been carried on for many years with satisfactory results, but the C. B. & Q. R. R., the Union Electric Light & Power Co. and the Standard Oil Co. of Indiana had not been producers of coal, at least in this district. Apparently the most impressive feature of the newest mines is their capacity, for in some cases it is planned that production shall be in the neighborhood of 1000 tons per hr. There are mine, now in this field having nearly that output, but these were not planned for such

Jan 9, 1919

By G. B. Gould

Every mathematical statement of a measure of anything (as distinguished from a count') is followed by a qualification—always implied if not explicity stated—-that the statement is only an estimate, which may vary from absolute accuracy within certain limits, according to the accuracy of the measuring instrument. This basic fact, so obvious to engineers, is not so well understood by many that make use of laboratory coal tests. The tolerances that must be allowed in measurements of coal quality are very important in both their commercial and engineering applications—and the significance of these tolerances depends upon the use made of the laboratory coal test. Only in recent years has there been any intensive study of this question of tolerances as applied to measurements of coal quality. There is very little in our published literature on the subject, and what has been published is not readily comprehended by those who sell coal, or buy coal and use it, unless they happen to have made a study of the subject themselves. There is great need for more widespread understanding of what lias been discovered and how it applies to the use of laboratory coal tests. What follows is an attempt to condense into a few pages the results of the major investigations so far reported, and to explain their meaning in simple nontechnical language, with the addition of some recent illustrative experiments. Determining Deviations in Quality It is necessary at the outset to distinguish between: (I) the accuracy with which one test indicates the quality on one lot of coal; and (2) the accuracy with which a test of one lot of coal represents the average quality of a commercial product, of which the buyer will presumably receive a series of shipments—perhaps many thousands of tons. It is necessary to make this distinction because coal is a variable material—a heterogeneous mixture of a variety of components—the quality of which will vary from one lot to another. Therefore an absolutely accurate determination of the quality (if that were possible) of one lot of a coal is an

Jan 1, 1938

By G. B. Gould

Every mathematical statement of a measure of anything (as distinguished from a count') is followed by a qualification—always implied if not explicity stated—-that the statement is only an estimate, which may vary from absolute accuracy within certain limits, according to the accuracy of the measuring instrument. This basic fact, so obvious to engineers, is not so well understood by many that make use of laboratory coal tests. The tolerances that must be allowed in measurements of coal quality are very important in both their commercial and engineering applications—and the significance of these tolerances depends upon the use made of the laboratory coal test. Only in recent years has there been any intensive study of this question of tolerances as applied to measurements of coal quality. There is very little in our published literature on the subject, and what has been published is not readily comprehended by those who sell coal, or buy coal and use it, unless they happen to have made a study of the subject themselves. There is great need for more widespread understanding of what lias been discovered and how it applies to the use of laboratory coal tests. What follows is an attempt to condense into a few pages the results of the major investigations so far reported, and to explain their meaning in simple nontechnical language, with the addition of some recent illustrative experiments. Determining Deviations in Quality It is necessary at the outset to distinguish between: (I) the accuracy with which one test indicates the quality on one lot of coal; and (2) the accuracy with which a test of one lot of coal represents the average quality of a commercial product, of which the buyer will presumably receive a series of shipments—perhaps many thousands of tons. It is necessary to make this distinction because coal is a variable material—a heterogeneous mixture of a variety of components—the quality of which will vary from one lot to another. Therefore an absolutely accurate determination of the quality (if that were possible) of one lot of a coal is an

Jan 1, 1938

By David B. Reger

The year 1936 in West Virginia was characterized by increased activity in natural gas. The number of actual completions was only slightly increased but many more wells were drilling than at the end of 1935 and there was almost feverish activity in taking new leases. This pronounced revival is partly due to the fact that the extremely cold winter of 1935-1936 showed that additional supplies of gas would be desirable and partly to the hope of finding new pools in the deeper sands. No new pools have actually been found, but the Oriskany sand (L. Dev.) development of Kanawha County, which was already assured by the end of 1935, was greatly extended into wider and richer territory. The Middle Devonian shale (Childres sand), reached incidentally by Oriskany exploration as well as by direct design, has been productive of gas in much wider areas of Boone, Lincoln, Putnam and Kanawha Counties than heretofore known. Routine drilling to the upper sands in dehed territory, also, was greatly increased, although not yet much reflected in completions. Thc supply of marketable gas, however, has been substantially enlarged. In preparation for further exploration there has been an extensive leasing campaign throughout the entire territory where gas seems at all probable, or ever possible. Exact figures are lacking, but new leases have certainly been taken on more than 1,000,000 arres. One operator estimates that 500,000 acres have been leased in the Appalachian geosyncline alone between Parkersburg and Charleston. Exploration, both for shallow and deep-sand gas, on some of these new leases is now under way. There was little activity in oil. No special search for new pools was made and none was found, but the usual routine drilling in old pools occurred. One major gas pipe-line enterprise was undertaken and completed. Operating technology was much the same as usual. In certain localities repressuring for oil has become a matter of routine, and in others the use of acid in treating small wells in calcareous beds has been continued. Financially, the year has been eventless. Some attempts to buy and

Jan 1, 1937

By C. D. Keen

In the latter part of the summer of 1913 the Conservation Commission of the State of Louisiana, under presidency of M: L. Alexander, decided to stop the waste of natural gas going on at the "burning gas-well," Located about 2 mile southeast of Oil City, La. On several occasions, both in newspapers and in reports, comment had been made on the condition of this well, its harmful effect on the Caddo gas field, and the considerable loss, estimated at several thousand dollars each month, caused by the escape of the valuable fuel., But nothing had been done to bring the well under control and prevent further waste of gas until the State Conservation Commission took the matter in hand. The gas fields of Louisiana are among the greatest in the country. So far most of the gas has been found in the Caddo field proper, although considerable development has been done in and around the city of Shreveport and near the town of Mansfield in DeSoto parish. To extend the life of the gas fields and to prevent the quick exhaustion of the supply of the natural fuel are matters of vital importance for this section of the country. Four gas companies have entered the Caddo field and supply the surrounding towns and cities With gas. The Arkansas Natural Gas Co. has pipe lines to Little Rock, Ark., and supplies gas to the following cities and towns in that State: Texarkana, Hope, Garland, Emmet, Prescott, Boughton, Beirne, Gurdon, Arkadelphia, Gum Springs, Mal-vern, Dsnaldson, Gifford, Perla, Beaton, Beauxite, Mabelvale, Bryant, Sheridan, Pine Bluff, Little Rock, Argenta, Pulaski Heights, and Hot Springs. The Southwestern Gas & Electric Co. transports gas to Mooringsport, Blanchard, Caddo, Rodessa, Oil City, Vivian, Bloomburg, Hosston, Ida, Dixie, Belcher, and Shreveport. The Marshall Gas Co. supplies gas to the town of Marshall, Texas. The Louisiana Co. has a line to Shreveport. In, the oil field the gas is used for drilling purposes, and the operators either have their own gas system or buy from the gas companies. At the present time the surrounding territory depends for its fuel supply on the Caddo field, and the importance of the conservation of the natural-gas

Jan 1, 1915

By Amos L. Beaty

The oil industry can prosper only if crude production is not excessive. This is true for several reasons. In the first place, the marketing branch of the business is so highly competitive that there is little room for profits in it. There are too many service stations, too many middle men or jobbers, too many refiners eager to press their products upon the market. And the battle is between the strong. If any money is being made in oil today it is by small marketers who buy products from the refining companies and sell on guaranteed margins. In the second place, refineries are overbuilt. There is a large surplus refining capacity. If refined stocks were drawn down they could and would be replenished in short time on short notice. This excessive refining capacity is not serious, however, if the supply of crude is limited to trade requirements. True, it may reflect upon the intelligence of the industry, but if there were a shortage of crude for a few years refining capacities would be readjusted. In the meantime no great harm could result from some idle capacity. It requires no computation to see that refiners could not produce surplus stocks of products from a short supply of crude. I have in mind, of course, the increased yields from cracking. Allowance must be made for that. Still, the picture is the same; less crude is required. I think we can have prosperity in the oil business if too much crude is not produced. A proper limit at this point would be felt all the way down the line. It would slow the refiner and slow the marketer inevitably. Once this constant pressure to make more and sell more is off, operations will be normal and there will be some return on investments. Peices in Relation to Production Potential production at this time is very large, and this condition has existed for many months. As a result the price of crude is low. It is below the average cost of production. Nevertheless, if restraints were withdrawn actual production would immediately increase and the situation would become even worse than it is now. Eventually, of course, the

Jan 1, 1932

By Louis Huber

DESPITE the fact that centrifugal fans were first developed for ventilating mines and that artificial ventilation was first practiced in mines, the lack of knowledge of mining men on mine ventilation in general, and on fan performances and characteristics in particular, is very much in evidence today. While it is true that mines are much better ventilated now than they were 20 to 30 years ago, we have made very little progress in the study of mine ventilation, or in mine ventilating fan design. Today the average mine operator is woefully dependent on the engineers of mine fan manufacturers when he is in the market for a fan, and this situation works to the disadvantage of both the operator and the manufacturer. The former may be imposed upon by an unscrupulous sales engineer and induced to buy a fan which is not the proper one for the mine; when it is operating it may be wasteful of power and even accessory to a serious mine disaster. More often, however, it is the fan manufacturer who is imposed on. If the operator asks the manufacturer to build for him a fan that will deliver a certain quantity of air against a certain specified pressure and requiring a specified number of horse power when operating under these conditions, the manufacturer may build a fan that will comply with these specifications to the letter. When the fan is installed it is frequently found that it is delivering a greater quantity of air against a lesser pressure or a lesser quantity of air against a greater pressure, and is requiring more horse power than specified in the first case and less than that specified in the second. In either case the operator usually upbraids the manufacturer for not meeting specifications, and refuses to pay for the fan. The trouble in either case outlined above is that the pressure necessary to force the specified quantity of air through the mine has been estimated incorrectly by the operator or his engineers. When a fan is designed and built to deliver a certain quantity of air against a certain specified resistance it will operate at its maximum efficiency only when it is operating under

Jan 2, 1926

By S. D. Baumer, P. M. Hulme

B. M. Larsen (U. S. Steel Co., Kearny, N. J.)—Could we have some sort of an estimate on the cost of calcium carbide for this treatment? Also, if you used calcium carbide on carbon-saturated iron, would some effect hold back the reaction? P. M. Hulme (authors' reply)—As far as I know we have not worked on carbon-saturated iron. About 3½ pct C is the highest we have worked on. As far as cost goes, it depends on how much sulphur You have to take out. It will run anywhere from $0.75 to $2.00 a ton overall cost including the cost of carbide per ton of metal treated. That is, using the efficiencies that we show in this paper. We are getting better efficiencies now. T. L. Joseph (University of Minnesota, Minneapolis, Minn.)—Did you say 2 lb of calcium compound? Mr. Hulme—That is based on 10 lb of calcium carbide per lb of sulphur removed. D. E. Babcock (Republic Steel Corp., Youngstown, Ohio)—We have run this type of desulphurization process at the blast furnace. We have desulphurized between 100 and 200 at the blast furnace and taken the iron right out of the furnace with an injector system. The process gave us quite varied results; stratified iron, high sulphur on the top and low sulphur on the bottom, and we decided it was impractical. Mr. Hulme Just what was the type of injection equipment? Dr. Babcock—Nitrogen gas for one injection method and we used fairly large gun equipment. We followed the same general type of pattern you show only on a larger scale. Mr. Hulme—It sounds very much like what we call the gale of wind method. We have very erratic results with that. Dr. Babcock—We have tried several types, and particle sizes. The operation was not satisfactory. Mr. Hulme—Of course, we have never tried it on that scale except on a continuous basis. That is the reason we abandoned the idea of working on 35 ton ladles on a batch principle and took it as it came out of the cupola and treated it on the fly on a continuous basis. Dr. Babcock—When you compare the relative effectiveness of the process as carried out, it does not give a very favorable comparison of that process which is already developed. We did not feel it was worth the

Jan 1, 1952

By Bruce W. Gonser

TIN is not yet classed as a rare metal, but it has taken a long stride in that direction in the last ten months. It is now in Group 1 of the War Production Board's critical list, along with such company as magnesium aluminum, and nickel. This is in sharp contrast with the position a year ago when the supply well exceeded demand, and tin was used when feasible in place of really scarce metals. The geographical sources of tin production in recent years are shown in Table 1. Preponderance of former production in southeastern Asia, particularly Malaya and the Netherlands Indies (but all now controlled by the Japanese). is entirely too marked to be funny. Of the 1940 known world production of 237,000 long tons nearly all was controlled by the United States, Great Britain, and their friends. Now their supply is from countries that produced only 28 per cent of that amount. This excludes China and Australia, which because of shipping difficulties and local consumption, cannot be expected to export much tin. In spite of some expected increase in production, therefore, the supply is, and will continue to stay for at least several years, way below that desired for even normal uses. Although deliveries to consumers in the United States alone

Jan 1, 1942

By Chester A. Fulton

SUPPLYING as it does a necessity for healthy animal and vegetable phosphate production is a most important industry. We human beings also are animal as this war so surely proves. Unlike many other elements no substitnite is available for phosphorus or its compounds. Marvelous as are modern plastics none can lake the place of phosphorus in making hone structures. As meassured in these times the phosphate industry is not a large industry. Output of phosphate rock, the original source of our agricultural and ,chemical phophates amounts to only some twelve million long tons per annum in the entire world. Phosphates are compounds of phosphorus, which is always found in nature combined with other elements. It never occurs in nature as such. The first choice of the element phosphorus is tie itself strongly to oxygen and then to water moisture - thus becomeing phosphlic acid. This phosphoric acid in turn hunts around for a base such as lime for instance and together they make phosphate of lime.

Jan 1, 1944

By Thomas L. Kesler

IF all of the 14 million tons of kaolin produced in Georgia through 1949 had been mined from a single deposit 20 ft thick, it would represent a mined-out area of less than 1 sq mile. This measure of depletion is in such strong contrast with the large size of the area shown in Fig. 1, from which most of the output has come, that there has developed an optimistic outlook concerning future supplies of kaolin equal in grade to that already mined. Dozens of mines are widely but not evenly distributed within this area, which consists mostly of parts of Twiggs, Wilkinson, and Washington counties. There are scarcely half a dozen kaolin mines elsewhere in the state that have been appreciably productive, although the areas in which they occur may have good possibilities. Most of the efforts to find new deposits, therefore, will be confined to the area shown in Fig. 1, for it is here that the industry has established its facilities, and prospecting is encouraged by relatively numerous outcrops and opened deposits of kaolin.

Jan 10, 1951

By S. F. Shaw

MINING conditions in Mexico during the current year have been most unfavorable, synchronizing with conditions in the United States, but the outlook for the near future is improving. The chief difficulties met with are because of the following conditions: severe drop in prices of metals; high smelting rates; high prices of supplies; inadequate means of transportation; low efficiency of labor. In comparison with pre-war prices for metals it cannot be said that prices are low, particularly for silver, which recently has gone to a level that would have been considered exceedingly good in 1912. But conditions have changed so greatly that only the most favorably situated properties can operate without loss.

Jan 1, 1921

By E. W. Engelmann

RAPID progress has been made during the past year in the copper mills throughout the country. Particular efforts have been made to increase the fine-grinding efficiency by the installation of larger classifying units operating in closed circuit with ball mills, such as the 78-in. high-weir Akins installation at the Phelps Dodge plant at Ajo, Ariz.; also the Type "FX" Dorr classifiers of Nevada Consolidated at McGill. Nev. and the "FX" Dorr bowl classifier of the Braden Copper Co. in Chile. Some of the copper milling plants in the Southwest, such as Chino in New Mexico and Ray Con. in Arizona, have replaced rolls operating wet in their fine-grinding circuit by rod mills. At Hollinger primary rod mills were formerly used in open circuit followed by pebble mills in closed circuit with classifiers. They now have primary ball mills in closed circuit with large extra heavy classifiers and no secondary mills. This new installation is producing the same grinding on 5000 tons per day with a reduction in cost of nearly 4c. per ton. At the Braden plant, in Chile, short-head Symons crushers have replaced 54-in. rolls, thereby in- creasing crushing capacity with some saving in maintenance cost.

Jan 1, 1939

By L. R. van Wert

CAREFUL research into the nature of the metallic state has yet to discover, with any certainty, its essential quality. We do riot yet know, for sure, what it is that makes the metallic elements different from, if not actually unique among, all created things. We do know, of course, that metals have certain more or less characteristic properties-they are hard, strong, and tough, and good conductors of heat and electricity, and these so-called metallic properties provide a definition of a sort. How- ever, it is the structure rather than the behavior of the metals which gives the really fundamental information necessary to the understanding of metallicity. But this information is not easily obtained. Nature has a way of keeping secrets. But happily we do possess some knowledge of how a metal is built up, and it is this matter, rather than the presentation of a formal definition, that will be discussed here.

Jan 1, 1937

Jan 1, 1908