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By AIME AIME

I would like to ask Bob Merrill whether he considers that horizontal concave curvature of a slope has any stabilizing effect, such as Jenike 1 suggested several years ago. The stabilizing effect is due to the restraint offered to radial movement by the curvature. We found in laboratory tests that if we constrained the rock with the same stresses as those measured in the pit then it would sustain a maximum stress about two or four times greater than when the same rock type was unconstrained. We are therefore definitely of the opinion that a constrained situation in a slope is favorable towards stability.

Jan 1, 1967

ENGINEERS AVAILABLE (Under this heading will be published notes sent to the Secretary of the Institute by members or other persons introduced by members.) Member, Cornell M. E., graduate, aged 31, married. Will soon complete 2 years' engagement in the Russian oil fields. Eight years' practical experience in drilling for and producing oil. Can speak Russian fluently and some French and German. Open for engagement. Interview after August 15, in the United States. No. 299. Member, graduate mining engineer. Married. Aged 38. For past 6 years, general superintendent of large silver mine in. Mexico. Desires connection with responsible mining company, preferably in the United States. Has had 15 years' experience in the United States and Mexico, including mine engineering, sampling, examinations,' milling and mine superintendence. No. 312. Metallurgist, 4 years' experience in electric furnace operation on steel, ferro-alloys and smelting of ores, both practical and research, desires position as metallurgist or superintendent. No. 314. Member, technical mining graduate. 5 years' experience in coal and metal mines and construction work. Married. Aged 27. Employed at present. Interview in Salt Lake City or Denver. No. 316.

Jan 10, 1916

Rougher Cells The photo shows one of three carloads of new Denver Equipment Co. rougher flotation machines destined for a single customer. [ ] Low level froth overflow on both sides, and double impeller mechanisms in an open-flow type tank, were designed to enable control of variable conditions in the rougher circuit for better metallurgy. Intense agitation and aeration are claimed, for effective recovery of low-grade mineral particles. Standard parts are used, interchangeable with regular Denver Sub-A units. The Super Rougher is now in production and a 2-cell No. 24 machine will be displayed at the Mining Show. Circle No. 1 Fans A line of industrial fans built for air or materials handling is available in eleven sizes from 670 to 44,000 cfm capacity from Westinghouse Electric Corp. The air hand¬ling wheel has backwardly-inclined blades. Circle No. 2 Trolleyphones The Femco Trolleyphone, plug-in model, 2550 series, is offered as a simple mine or mill communications system by Farmers Engineering & Mfg. Co. More compact, easier to install and service, the new model is powered from existing trolley wire or power line. Circle No. 3

Jan 1, 1952

By E. F. Jr. Young, H. E. Steinman, G. C. Smith

Through a progressive laboratory and pilot-plant program Jones & Laughlin Steel Corp has analyzed and corrected mine drainage pollution problems at all of its coal mines. In conducting this program, the company found no "typical" drainage discharge. Each discharge point at each mine was unique, so that varied approaches were needed to eliminate stream pollution. To illustrate the variety of these approaches, the treatment of drainage from foul, discharge points at three mines in Pennsylvania will be considered here. The flows and critical analyses of the drainage sources and treated effluents arc shown in Table I. Hydrated Lime Works at Thompson Borehole The discharge stream from the Thompson bore- hole at the Vesta No. 5 mine flowed into a small branch creek where it created a "yellowboy" deposit and affected aquatic life. Investigation indicated that hydrated lime would neutralize the acid and precipitate ferric iron without aeration. Treatment of the 150.000-gpd flow, however, created about 4000 gpd of wet sludge for which there was no nearby accumulation site. With State approval, this sludge was deposited through an unused borehole into an abandoned section of the Vesta No. 6 mine several miles away.

Jan 1, 1970

ENGINEERS AVAILABLE (Under this heading will be published notes sent to the Secretary of the Institute by members or other persons introduced by members.) Member, technical graduate, aged 40, member Institute of Mining and Metallurgy 16 years, with varied experience. Actual underground work,. foreman, surveying, milling, mine examination, superintendent, manager, and other positions of trust. Several years' European practice. Familiar with flotation process. Desires responsible position. References furnished. No. 172. Member, aged 40, graduate Massachusetts Institute of Technology. Twenty years' successful experience as blast-furnace superintendent (merchant and steel works), covering operating, remodeling and? building. General superintendent and general manager of proposition comprising blast furnaces, coal and coke, and iron-ore operation, etc. Good organizer and handler of men. Desires position in above line anywhere. No. 173. Member, technical graduate, aged 43, with 20 years' experience in management of gold, silver, and copper properties and also coal and smelting properties in United States, Canada and Mexico. Owing to illness compelled to resign. Now open for engagement. No. 174. Member, technical graduate, with many years' experience with large smelting and refining companies as chemist, metallurgist, and superintendent desires position. No. 175.

Jan 1, 1915

Steel Tape The new Lufkin Royal Ni-Clad steel tape, made in 25, 50, 75, and 100-ft sizes, is stated to cost less than any other steel tape on the market. Figures and graduations are an integral part of the steel and the nickel plated surface is rust and corrosion resistant. Circle No. 1 Lift A manually operated and propelled hydraulic lift marketed by Century Products Co. weighs only [ ] 150 lb, but the 23x24 in. platform will raise 1000 lb from floor level to 4 ft height. Circle No. 2 Scintillation Counter The Scintillator from Precision Radiation Instruments, stated to have 100 times the sensitivity of the Geiger counter, is suitable for prospecting and may be operated from plane or moving vehicle. The instrument is contained in a 2-lb probe and the belt mounted battery box weighs less than 4 lb. Circle No. 3 Generators Wincharger Corp. announces development of a Speedy-Shift wheel-barrow base type attachment for model 700, 1800 and 5000 engine-generator sets. Portability of the engine-generator sets themselves has been improved by belted construction for higher operating speed and maximum weight reduction. Circle No. 4

Jan 1, 1952

ENGINEERS AVAILABLE (Under this heading will be published notes sent to the Secretary of the Institute of members or other persons introduced by members.) Member, Cornell M. E., graduate, aged 31, married. Will soon complete 2 years' engagement in the Russian oil fields. Eight years' practical experience in drilling for and producing oil. Can speak Russian fluently and some French and German. Open for engagement. Interview after August 15, in the United States. No. 299. Metallurgist, four years' experience in electric furnace operation on steel, ferro-alloys and smelting of ores, both practical and research, desires position as metallurgist or superintendent. No. 314. Member, technical mining graduate. 5 years' experience in coal and metal mines and construction work. Married. Aged 27. Employed at present. Interview in Salt Lake City or Denver. No. 316. Member, American, aged 39, married, desires position as superintendent or mine superintendent. 14 years' experience in opencut and underground work. 12 years' Spanish, Portugese, Cuban and Mexican labor. Fluent Spanish. Good training in first aid and safety first. Specialty of high explosives and steam-shovel work. Good costs. Go anywhere, but tropics preferred. References. Interview, New York or Philadelphia, No. 318.

Jan 10, 1916

By Arthur Foote

AT THE end of the year 1914, the main North Star incline shaft had reached the 6300-ft. level, and encountered a vein dipping Southwest, or, exactly opposite to the North Star. Subsequent development failed to find the North Star vein continuing beyond this intersection, so the 6300-ft. level proved to be the bottom level of the North. Star vein, and very little ore was found below the 5300-ft. level. The new vein was called No. 1 vein. Development work carried on for the next 10 years discovered a third vein, called No. 2, branching off about 1200-ft. to the east, with a North-south strike and a west dip. No. 1 vein had about 900 ft. of backs above the 6300-ft. level before reaching the boundary line of the property, and No. 2 vein died out about 800 ft. above. During these 10 years, the money spent on development was increased from $54,000 in 1914 to $184,000 in 1924; the ore reserves steadily diminished until it was evident that the mine must close down unless by some means a large tonnage of ore could be developed quickly.

Jan 1, 1930

By JESSE L. MAURY

ONE OF the most hopeful features of the current depression is the discussion which it has en- gendered of ways and means to counteract similar recurrences in the future. 1t is widely recognized that fruitful attack will be directed toward the steady employment of labor, through which the purchasing power of this preponderant class in society will be maintained. S. A, Lewisohn's article' has presented the major factors to be considered; the physical suffering and mental torture endured by those who are deprived of income through no fault of their own, the direct economic losses' sustained in the degradation of 'great, numbers of our population and the disintegration of efficient working forces, and the prime responsibility of owners and managers.

Jan 1, 1931

By C. E. Lundin, D. T. Klodt

The binary alloy systems, Y-Ti, Y-Zr, and Y-Hf, have been investigated throughout their entire composition regions. There is no compound formation in any of the systems, and each system is characterized by a single eutectic reaction. The eutectic compositions and temperatures are as follows: A eutectoid reaction pct Y and 870°C occurs in the Y-Ti system, whereas a peritectoid reaction,: pct Y and 880°C occurs in the Y-Zr system. Peri-tectic-type reactions at temperatures above the eutectic levels are postulated for the yttrium and hafnium transfovmations. The development of the technology of yttrium has been given considerable attention during the past few years, and studies of binary phase equilibria have, of course, taken a prominent position in this development. In many respects yttrium, in the third group of metals of the periodic table, is similar to the adjacent group of metals, titanium, zirconium, and hafnium, and the knowledge of the phase relationships of yttrium with these metals is basic to their technology. MATERIALS AND EXPERIMENTAL PROCEDURES Materials. The metals for this investigation were supplied by the General Electric Co., Aircraft Nuclear Propulsion Department. The yttrium was in the form of an arc-melted ingot, and the other metals were in the form of high-purity, iodide-Process crystal bar. Table I lists the purities of these materials. Alloy Preparation. Melting was done by conventional techniques in a nonconsumable electrode arc furnace in an atmosphere of purified argon. Melting conditions for each binary system were the same. Each alloy button was inverted and remelted several times to assure homogeneity. Accurate weights of the charges and resultant alloy buttons were obtained to indicate deviations from intended compositions. No chemical analyses were obtained since melting weight losses were consistently in the range of 0.1 to 0.2 pct of the total weight. 10- or 20-g buttons for each 5.0 wt pct composition increment were melted to survey the three individual alloy systems. Additional alloys differing in composition by 1.0 or 0.1 wt pct increments were also melted to study selected regions of the systems. Metallograpllic Techniques. Standard metallo-graphic techniques were followed for mounting and rough grinding. Preliminary polishing was accomplished using 6-u diamond paste as an abrasive on a Metcloth Lap. Final polishing was done on a Microcloth-covered wheel using 1-u diamond abrasive paste. Purified kerosene was used as a lubricant for both polishing stages. • sothermal- Annealing. Alloys were sectioned for as-cast structlure examinations and then homogenized in preparation for isothermal-annealing treatments. Homo{:enization was accomplished by cold pressing the alloy buttons followed by 72-hr anneals at 1100c. The alloys were encapsulated in Vycor or quartz for the homogenization treatments or for isothermal anneals. Resistance-wound or resistance-element tube furnaces were used for the annealing treatments. The homogenized alloy buttons were cold rolled until cracking occurred or until a -in. specimen thickness was obtained. Small -in. square) specimens for the isothermal anneals were then sawed from the alloys. Each specimen was wrapped in tantalum foil before being sealed in the capsule. Temperatures during the anneals were controlled The time at temperature necessary to equilibrate the structures during the anneals was determined for each alloy system by holding triplicate specimens of alloys at a constant temperature for three different periotls. The specimens were quenched and examined microscopically to determine the number and amounts of phases present in the micro-structure as a function of time. Melting Studies. Eutectic temperatures of the three alloy systems were established from the results of incipient-melting studies conducted on as-cast alloys. Specimens to be melted were suspended on a tungsten wire inside a graphite cylinder placed in a glass vacuum chamber. An optical pyrometer was used to follow the temperature of the specimen as it was inductively heated in a high vacuum. The temperatures were corrected for emissivity losses by standardizing the pyrometer with known-melting-point metals. Accuracy of the temperature measurements is estimated to be + 10°C. The melting point of the yttrium was determined to be 1550°C by this technique. The invariant-temperature levels were also checked by an anneal-quench technique. This technique consists of annealing a series of

Jan 1, 1962

By Lloyd Pollish, Robert N. Breckenridge

SUCCESS in any underground mining operation is determined by accessibility of the orebody, which in turn is dependent upon maintenance of passageways to the mining zones and temporary support of the voids caused by extraction of ore. This is accomplished by one or a combination of the following methods: timbering, back-filling, pillaring, or, more recently, rock bolting. Timbering has usually been the principal means of maintaining these underground openings necessary for mining operations. Timber, however, does not prevent ground movement beyond the scope of localized sloughing, which is indicated by the gradual failing of the timber itself. Besides this, timbering has always been a costly process, and with the decline of available supplies of timber close to the mining areas, mining men have constantly sought other methods of controlling ground. Rock bolting is now replacing timbering at an ever increasing rate. Experience has proved that this form of ground support is just as applicable to blocky igneous rock as to stratified rock. Besides preventing sloughing of the walls and back of underground openings, Fig. 1, rock bolting has a stabilizing effect on the surrounding ground in much the same manner that steel reinforcing rods add to the strength of concrete structures. Further, rock bolting is flexible and may be applied to any shaped excavation, whereas timber sets are in a fixed pattern and the ground must often be changed to conform with this pattern. Rock-bolting installations were made in metal mines of the Northwest as early as 1939. An exhaust air crosscut was driven that year in one of the Butte mines of the Anaconda Copper Mining Co. The crosscut was rock-bolted and gunited at the time it was driven and is still being used to exhaust hot humid air from the 3400 level of the Belmont mine. It is interesting to note that no sloughing or caving has taken place in the 14 years it has been open. Even though these early installations of rock bolts were successful, few men recognized their potentiality until recent years, when the coal mines started their programs of mechanization and the great trend toward roof bolting began. In some areas of the Northwest stopes that previously required heavy timbering and close backfilling are now being mined by the more economical cut-and-fill and shrinkage methods. When used in conjunction with timbering, rock bolting increases the efficiency of the operation by decreasing hanging wall dilution and by making it possible to blast larger rounds. Most of the rock bolts installed to date in mines of the Northwest have been the 1-in. diam slot and wedge type, but there has been a recent trend to- ward using the 3/4-in. diam expansion shell bolt shown in Fig. 2. In addition to these commercially manufactured steel bolts, wooden bolts have been used with considerable success by the Day Mines of Wall'ace, Idaho. Installation of the slot and wedge type requires three distinct operations, with tools for each operation: 1—drilling the hole to proper diameter and depth, 2—setting the bolt, and 3—tightening the nut. Holes are drilled and bolts set with pneumatic rock drills. A number of setting or driving tools have been used successfully, but most follow the same general pattern. Usually the driving tool is designed to accommodate a short length of drill steel on one end and the rock bolt on the other end. In this manner the hammering effect of the rock drill is transmitted through the steel and driving tool to the bolt. When machines not having stop rotation are used, slippage is allowed between the driving tool and bolt or between the drill steel and driving tool. The rock bolt nuts are tightened either with pneumatic impact wrenches or with hand wrenches. Impact wrenches are desirable because they are faster and assure adequate tightness. Expansion shell bolts have the following advantages over slot and wedge rock bolts: 1—No special equipment other than a wrench is needed for their installation. 2—Installation is faster. 3—They are removable. 4—Holes need not be drilled to a specific depth as the expansion shell will anchor anywhere along the length of the hole. These advantages are offset somewhat by the lesser strength of the bolt, since expansion shell bolts are generally made from 3/4-in. diam steel as compared to 1-in. diam steel for the slot and wedge type. One manufacturer, however, is now fabricating expansion shell rock bolts from steel of high tensile strength, which gives this ¾-in. bolt a much greater strength than that of the mild steel bolt. Table I illustrates tests made by the Anaconda Copper Mining Co. to determine the proper hole size to use with various types of bolts and to determine

Jan 1, 1955

By W. R. Kanne, P. R. Strutt, R. A. Dodd

A study has been made of the creep behavior of ß-NiAl of stoichiometric composition in the temperature range 475" to 775°C. Single crystal tensile specimens were deformed under a constant applied load. From slip line studies and tensile axis rotations it was concluded that the crystals deformed by pencil-glide on (100) and (110) planes with a (100) slip direction. Electron microscope thin-film studies showed evidence for profuse cross-slip, and the dislocation Burgers vector was determined to be (100). There was no tendency for the dislocations to lie in definite slip planes, although a strong alignment of segments of edge dislocations was frequently seen. The activation energy for creep in the temperature range 475" and 775°C was judged to be much lower than that for creep at temperatures above 775°C. It is possible that the rate-controlling process is the thermally activated cross-slip of screw dislocations. In recent years considerable interest has developed in the possible use of high-melting-point intermediate phases for high-temperature applications necessitating good creep resistance. Ordered alloys such as Ni3A1, modified by alloying additions, have received particular attention, culminating in the recent development by Pratt and Whitney of single crystal turbine blades.' The intermediate phase NiAl has considerable theoretical interest from a creep standpoint because not only is it ordered up to the melting point (-1650°C at stoichiometry) but it contains a high concentration of structural vacancies on the aluminum-rich side of stoichiometry. These vacancies are known to exert a strengthening effect under some conditions,' but in addition they might be expected to affect high-temperature creep rates through dislocation climb. The present paper deals with the slip line and dislocation structures developed during creep of stoichiometric NiAl between 475" and 775C, and with possible attendant creep mechanisms. MATERIALS AND TEST TECHNIQUES NiAl ingots of stoichiometric composition were prepared by induction melting 99.996 pct A1 and 99.98 pct Ni (kindly provided by the Kaiser Aluminum Co. and the International Nickel Co., respectively) in 100 cc pure alumina crucibles in a helium atmosphere. No chemical melting flux was used in order to avoid con- tamination of the alloy. Each ingot was slowly direc-tionally solidified to avoid porosity and to produce very large grains up to 2 in. in length. In this way, ingots were obtained which were suitable for sectioning into single crystal creep specimens. Chemical analysis indicated that all alloys were within the range 49.6 0.3 at. pct Ni. For the present investigation, identical rectangular single crystal blanks were cut vertically from one particularly large crystal in an ingot using a series of three diamond cut-off wheels with appropriate spacers. Thus, all sliced crystals had the same orientation with the tensile axis parallel to the long side of the rectangle; the initial orientation of the tensile axis is shown as S, in Fig. 1. The blanks were homogenized at 1250 to 1300°C for 48 hr and subsequently cooled slowly to room temperature. A gage length of rectangular cross section and about 0.75 in. in length was prepared on each specimen using an electrolytic lathe and a dilute nitric/phosphoric acid electrolyte. The gage length cross section was 0.250 0.0005 in. by 0.040 ± 0.0005 in. Holes to accommodate tensile grips were electrolytically machined using a rotating acid jet. After creep testing, this same technique was used to cut discs for transmission electron microscopy. Thus, all shaping was done electrolytically, the only exception being that (122) sections were spark-machined from some speci-

Jan 1, 1970

By AIME AIME

THE best meeting ever held, was the opinion expressed by a number of those who attended the annual meeting of the Institute in New York, Feb. 18 to 21, and there was an atmosphere of friendliness and good fellowship about it that fully justified the feeling. In numbers it was not quite so large as last year and unless the Engineering Societies should build for themselves a new building it is probable that no meeting can be larger, in respect to numbers, than that held in 1928, which was only made possible by the circumstance that the eighth floor of the building happened to be, temporarily vacant at the time. The number of rooms available for -sessions that were provided when the building was built long ago proved inadequate, and it is only by the expedient of obtaining the temporary use of the board and committee rooms of other societies that it is possible to arrange for the over 40 sessions that must be spread over the four days of the meeting. The-fifth floor, where. a buffet lunch is served each-day, has reached its full capacity and it seems quite evident that any future development of Institute meetings must be along the lines of quality, not size.

Jan 1, 1929

By Frank Firmstone

In April, 1873, No. 2 furnace at the Glendon Iron Works being out of blast, it was decided to alter it from an open to a closed top. The three side flues, through which a part of the gas was formerly taken off, were 15 feet below the top, and as, for various reasons, it was not convenient to cut new flues through the brickwork at the top, as is commonly done with closed-top furnaces, a modification of Coingt's charger was employed. This apparatus, as figured by De Vathaire,* consists of a cup or hopper, like that used with the cup and cone, and a central pipe for taking off the gas, which descends some distance into the furnace, and has a projection around it forming a seat for a ring of a triangular cross-section, which closes the opening between the cup and the central gas-pipe. The charge is put into the cup, and by lowering the ring, is thrown into the furnace, a part going outside of the ring toward the walls, and a part through the inside toward the gas-pipe. In this form the apparatus was not applicable, for: 1st. With a gas-pipe three feet in diameter, in a top eight feet in diameter, the openings left by lowering the ring would not be large enough to let lump coal pass through. 2d. For the charger to shut tight, the ring must bear equally against the projection made for it on the gas-pipe, and against the edge of the cup. This would not be difficult to effect when the apparatus is first put up, but a comparatively small change in the relative position of the parts, such as is almost certain to occur from expansion, would cause the ring to touch the pipe or the cup, whichever happened to be the lower, first, and leave a leak between it (the ring) and the other. In the plan adopted (Figs. 5 and 6, Plate I), the central opening in the ring is closed by the bottom of the gas-pipe, whereby more room is left for the passage of the stock when the charger is open, than if the pipe descended into the furnace; and the pipe, instead of being rigidly supported, rests on the ring, when the charger is closed, and follows it for two or three inches as it opens, until stopped by the counter-balance lever C. When the ring is raised to close the furnace top, it comes in contact first with the bottom edge of the gas-pipe, then both are raised together, until stopped by the ring touching the edge of the cup. In this way a good joint is made at both places.

By W. R. Bean

Probably few, if any, of the many serious problems confronting malleable foundries have been more difficult of solution than the question as to why malleable that is ductile, black in fracture, and normal in all respects before galvanizing should, by that process, be rendered brittle, brilliantly crystalline or "white" in fracture, and of low resistance to shock. So far as we are aware, the technical literature contains no data or discussions on this subject, except two referencesl,2 of a general character. It is apparently a question that every one concerned, producer and consumer alike, has been willing to evade as far as possible. Various theories as to the cause of the deterioration have been given but such checking of these theories as we have done indicates that there was no sound basis for most of them. This work on the galvanizing of malleable was first undertaken in 1916, and has continued until the present time. We now feel that for all practical purposes we have reached a solution and are glad to be able to offer it in a form that can be readily applied to production processes. It is impossible to give here a detailed account of the early work done on this problem. A great number of tests were instituted and an enor-

Jan 1, 1923

By W. R. Bean

Probably few, if any, of the many serious problems confronting malleable foundries have been more difficult of solution than the question as to why malleable that is ductile, black in fracture, and normal in all respects before galvanizing should, by that process, be rendered brittle, brilliantly crystalline or "white" in fracture, and of low resistance to shock. So far as we are aware, the technical literature contains no data or discussions on this subject, except two referencesl,2 of a general character. It is apparently a question that every one concerned, producer and consumer alike, has been willing to evade as far as possible. Various theories as to the cause of the deterioration have been given but such checking of these theories as we have done indicates that there was no sound basis for most of them. This work on the galvanizing of malleable was first undertaken in 1916, and has continued until the present time. We now feel that for all practical purposes we have reached a solution and are glad to be able to offer it in a form that can be readily applied to production processes. It is impossible to give here a detailed account of the early work done on this problem. A great number of tests were instituted and an enor-

Jan 1, 1923

By W. T. Isbell

Although the pressure to meet the heavy demand for lead still took precedence over new metallurgical developments in the field of roasting, smelting, and refining of lead in 1948 there nevertheless has been considerable activity in the experimental development of new processes and improvements as well as plans for the modernization of many plants both here and abroad. Increasing labor and material costs have stimulated the trend to greater mechanization, revamping of flow sheets, and construction of larger units wherever possible. Although there have been many serious labor stoppages in the United States, Mexico, and Europe, labor supply has improved in most plants even if it has fallen off in efficiency.

Jan 1, 1949

By Arthur F. Taggart

The quality of aggregate materials is. of major importance in governing durability and permanence of concrete structures. The problem of selecting suitable aggregate materials is two-fold. Geological factors include the type and character of the aggregate source, presence of known or suspected reactive constituents, and presence of thermally incompatible materials. Laboratory investigations include petrographic studies, soundness and reactivity tests, and tests of thermal properties. The importance of each factor in the selection of satisfactory aggregate material is considered in detail.

Jan 1, 1950

By Jay A. Carpenter

IN six years the construction of Hoover Dam and the power plants probably will have reached the operating stage and this vast new source of power will then be continuously available for industry. The height of the darn will be 580 ft. and the average annual flow of the Colorado River is calculated at approximately 24,000 cu.ft. per sec. If this full head and average flow can be maintained the year round, about one million horsepower will be generated. The U. S. Reclamation engineers, taking into consideration the probable range in flow and head, have set the figure for power contracts at 660,000 firm horsepower, which can be assured at all times of the year. During the months of heavy run-off of water from the Colorado River Basin the power plants should be able to generate the full 1,000,000 hp. capacity of the power plants, so there will be 340,000 excess or secondary horsepower. The cost of firm power at the switchboard will be close to 2.15 mills per kw.-hr., equal to $14.05 per hp.-yr., and the cost of the secondary or off-peak power will be close to 0.8 mills per kw.-hr., or $5.22 per hp.-yr. In no place in the country can such cheap power be obtained today. The electrochemical industry is in a state of flux because the power costs from its old sources have increased so much (to $30 per hp.-yr. at Niagara) that the industries have had to seek new sources, so they have gone to Canada and Norway and built new plants.

Jan 1, 1932

By AIME AIME

THE American copper mining industry is threatened with disintegration and destruction. This threat is not one which may only materialize in the distant future. The destruction has already commenced. At present, many domestic mines have already closed down. .Others are operating on a greatly curtailed basis. Those operating are doing so only at tremendous loss-because the selling price of copper is below the cost of production and rapidly diminishing financial resources and credit clearly forecast the early suspension of operations in most of the industry. Unemployment in the mining districts is increasing by leaps and bounds. While this condition is due in some measure to the present unsatisfactory state of business in general, the copper industry, unlike other lines of business, sees no possibility of recovery without definite aid. The fundamental, underlying cause of present conditions in the American copper mining industry is the unprecedented rise in foreign production, and the basic change which has taken place in the world copper industry in the last three years. The American industry had begun to feel this change early in 1929 long before the general collapse of business in the fall of that year. While the distress in the industry is undoubtedly aggravated by the present economic depression, it nevertheless would have arrived and. have been present at this time, regardless of general business conditions.

Jan 1, 1932