Search Documents

By A. C. Fieldner

THE total annual energy production from coal, petroleum, natural gas and water power has been increasing at a fairly constant rate during the thirty years ending in 1930. But since 1913 the demand for the competitors of coal has increased at a rate faster than that for coal. During the last twenty years, the curve of coal production has had a generally horizontal trend; in fact, the 1930 production of coal was six per cent less than that of 1913. Economists attribute this loss of demand to greater efficiency in coal utilization and to displacement of coal by oil and natural gas. These two factors are about equally responsible, and it is evident that research has been intimately concerned with both. About sixty per cent of the bituminous coal mined in the United States in 1929 was used for generating steam, either in stationary or locomotive boilers. A decade ago seventy per cent or more was used for this purpose. This change is due largely to tremendous advances in fuel economy.

Jan 1, 1933

By D. H. Thompson, A. W. Tracy

Season-cracking is a type of failure of brass that results from the simultaneous effect of stress and certain corrodants. The object of this paper is to present data that will aid in a more complete understanding of the mechanism of season-cracking and related phenomena. Results presented show that certain high copper alloys are susceptible to season-cracking or stress-corrosion cracking, and possible explanations are discussed. Starting at least as far back as 1906, many papers have been devoted to this subject but the symposium1 held in Philadelphia in 1944 is the richest source of information. In order to study season-cracking, several of the many variables were held constant so as to learn the effects of others. Season-cracking is generally understood to refer to the corrosion cracking of brass having internal stresses;²,³ it is a special case of the general stress-corrosion cracking. Inasmuch as applied stresses are more readily produced and controlled, they were used exclusively in this research and the resulting phenomenon must he called stress-corrosion cracking.²,³ Only constant tensile stresses were used. The agents believed to be most frequently responsible for season-cracking are ammonia. amines and compounds containing then]. Both moisture and oxygen also appear to he necessary. Therefore, an atmosphere containing ammonia, water-vapor and air was selected for these tests. Briefly, the work consisted of exposing sheet metal specimens, having a reduced section ¼ by 0.050 in., of copper-base alloys to the effect of static tensile stresses between 5,000 and 20,000 psi and simultaneous contact with a. continuously renewed atmosphere containing 80 pct air, 16 pct ammonia and 4 pct water vapor at 35°C. The gas mixture and the speci- mens were maintained above the dew-point. The time-to-failure in minutes was the primary measure of results. In order to limit the experiment to finite time, it was considered that a specimen which had neither failed nor undergone microscopically detectable cracking in 40,000 min. (4 weeks) while under a stress of 10,000 psi or more could be considered immune to cracking. This is merely a convenient limit and is not to be considered proof of immunity. Supplementary tests in the absence of stress using weight loss or microscopical appearance as measures of attack were made. Apparatus The apparatus used in this research is shown in Fig 1. To facilitate the description it may conveniently be divided into six parts: stress-producing units, test chamber, gas train, electrical controls, timers and gas analysis device. A stress-producing unit is shown in an exploded view at the left in Fig 2. At the right is an assembled unit with a specimen in place in the lower portion; it is this part that remains in the ammonia atmosphere during a test. The upper part contains a spring, a central threaded rod, a large nut and necessary washers, pins, and so forth. Stress is produced in the specimen by screwing down the top nut against the spring, thus putting a tensile load on the central rod and so on the specimen. The wrench that turns the nut by extending through the upper cap, is seen at the upper right of the figure. The magnitude of the load is gauged by measuring from the pin that extends through the side of the tube, to a fixed point on the large flange. Measurement is made with a vernier beam caliper, shown at the right of the figure. The necessary spring compression to give a desired stress is calculated from the calibration curve of the spring and the dimensions of the specimen. The test chamber, center Fig 1, consists of a thermally insulated steel box 32 in. long by 10 in. high by 7 in. wide. A horizontal baffle reaching nearly to each end divides the chamber equally. Below this baffle are inlets for air and ammonia, a heating coil and a fan. Thus the gases are warmed and mixed in the lower level and flow past the specimens in the upper level. A thermo-regulator and thermometer project into the upper space. The top is pierced by 12 ports flanked by 3/8 in. threaded studs. A test starts when a port is opened and a unit containing a stressed specimen is thrust through it and bolted down against a neoprene gasket. The test chamber is held at 35°C. The gas train, right rear Fig 1, carries ammonia and air continuously to the test chamber. Tank ammonia passes through two reducing valves, a needle valve, a flow meter and into the test chamber. The air from either the plant compressor or a small laboratory compressor passes through wool towers and flow controls to the flow-meter. It then bubbles through water at 34°C and through a heated line to the test chamber. Electrical controls, left rear, Fig 1, provide rectifiers and mercury relays for the test-chamber and humidifier-heating-control circuits and outlets for

Jan 1, 1950

[PRESIDENT E. DEGOLYER, District 0 NEW YORK, N. Y. PAST PRESIDENTS J. V. W. REYNDERS, District 0 . NEW YORK, N. Y. SAMUEL A. TAYLOR, District 3 PITTSBURGH, PA. FIRST VICE-PRESIDENT GEORGE OTIS SMITH, District 4 .WASHINGTON, D. C.]

Jan 1, 1928

By L. D. Godshall

A great deal has been written of late regarding the loss of silver in assaying; very discordant results have been published by different writers, and much uncertainty exists concerning even approximate losses in a careful determination of silver, as represented by a fire-assay. In the present paper it has been the aim of the writer to determine as accurately as possible the losses sustained by silver, under certain specified conditions, during the process of cupellation. Such losses are well known to be due to absorption by the cupel and volatilization. The conditions, however, which govern these losses are not believed by the writer to be so well understood. The most important of these are : 1. The effect of variable quantities of silver used. 2. The temperature of cupellation. 3. The character and quantity of impurities in the lead button. 4. The weight of the lead button. 5. The nature of the cupel. The following experiments were made for the purpose of demonstrating, as nearly as possible, the total loss of silver in cupellation under the most favorable conditions to be obtained in commercial assaying. Chemically pure silver and pure lead were taken. The latter was obtained from test-lead, first melted into a bar, from which pieces of the desired weight were cut and accurately weighed. The experiments recorded in this paper were planned by the writer, but executed throughout by Mr. J. N. Walker, whose ability as an accurate, careful and painstaking assayer is too well known and recognized throughout the West to require any further endorsement from me.

Jan 1, 1897

By AIME AIME

MINERALS and mineral resources are recognized as one of the things that nations are prone to quarrel about. The territory that was arbitrarily incorporated into the Polish Republic after the World War produces a variety of essential minerals on a substantial scale. The accompanying table has been compiled to give some idea of the relative importance of this production. Poland, before the recent war started, had an area of 150,000 sq.mi., just a little larger than the State of Montana. Its population was 32,000,000, equal to that of New York, New Jersey, Pennsylvania, Connecticut, and Massachusetts. Though not a highly industrialized country it nevertheless has important mines, steel plants, petroleum refineries, and sundry metal-fabricating manufactories. Coal, petroleum, iron and steel, zinc, lead, pyrite, potash, and salt are produced in excess of the country's domestic consumption. It has no appreciable production of copper, chromium, tungsten, nickel, tin, mercury, manganese, aluminum, magnesite, fluorspar, or graphite.

Jan 1, 1939

By W. C. Maurer

A drilling-rate formula for roller-cone bits is derived from rock crater-ing mechanisms. This formula holds for "perfect cleaning", which is defined as the condition where all of the rock debris is removed between tooth impacts. Under these conditions, the drilling rate is directly proportional to the rotary speed and to the bit weight squared, and inversely proportional to the bit diameter squared and to the rock strength squared. Under imperfect cleaning conditions, such m those usually present in field drilling, re-grinding of the cuttings occurs under the bit, and the drilling rates fall below those for perfect cleaning. INTRODUCTION Drilling with a roller-cone bit consists of two fundamental operations: the formation of craters under the bit teeth, and the removal of the broken rock from the craters. To delineate the mechanisms of drilling, it is first necessary to understand the mechanisms involved in the formation of individual craters and then to relate these mechanisms to the over-all drilling operation. CRATER FORMATION When a bit tooth impacts a rock, the rock is elastically deformed until the crushing strength of the rock is exceeded, at which time a wedge of crushed rock is formed below the tooth1, 2 as shown in Fig. 1. As additional force is applied to the tooth, the crushed material is compressed and exerts high lateral forces on the solid material surrounding the crushed wedge.- en these forces become sufficiently high, fractures are initiated below the tooth and propagate to the free surface of the rock. The trajectories of these fractures intersect the principal stresses at a constant angle,'s4, as predicted by both Mohr's and Griffith's theories of failure. It has been experimentally 3,1 .6 that the volume of an impact crater, V,, varies as where Ec is the total energy imparted to the rock during the formation of the crater, and E is the threshold energy required before cratering is initiated (Fig. 2). Indexing experiments' have shown that, when there is a second free face to which the crater can fracture, a larger volume of material is removed and that above a transition zone there is a linear relationship between V, and Eo., which has a slope equal to the relationship for the single crater. The beneficial effect of indexing tends to offset the threshold energy requirement to a large extent, as shown in Fig. 2, and the relationship is closely represented by Rate-of-loading effects have been used to explain the nonproportional relationships usually obtained between drilling rate and rotary speed. The data4, in Fig. 3 show that the Ec/Vc parameter remained constant for craters produced with impact velocities ranging from 10 to 8,000 ft/sec. Since no rate-of-loading effects were detected over this wide range of loading rates, it seems improbable that there would be detectable rate-of-loading effects present in the small changes in impact velocities produced by varying the rotary speed. The writer has shown (Fig. 4) that, for craters produced in rock by impacting spheres, where X is the depth of penetration. Simon2 has shown that this relationship also holds for craters produced in rock by penetrating wedge-shaped chisels. The energy used in crater formation is

By H. Kenworthy, R. B. Fisher, R. G. Knicherbocker, M. M. Fine

The progress made to date in the mineral dressing of complex Arkansas titanium ores is reported in this paper. Concentrates of rutile, a dioxide of titanium, were produced by treating a submarginal ore from the Magnet Cove Rutile Co., Inc., Magnet, Ark. The rutile recovery at present is 45 to 50 pct of the total TiO2, with the possibility of increased recovery with additional research. The work reported herein is part of a general study which will later include results of investigation of other titanium ore bodies in the Magnet, Ark., area. The fragile character of the rutile minerals, the softness of the gangue, the occurrence of pyrite and leucoxene, and the considerable proportion of extremely small size rutile in the presence of montmorillonite- and illite-type clays in the Magnet Cove open-pit mine are the important factors in the mineral dressing of this submarginal rutile ore. History The occurrence of titanium minerals in the Magnet Cove area of Arkansas was recognized as early as 1890, but it was not until about 1912 that any appreciable prospecting for the minerals was undertaken. At that time drilling was begun, a shaft was sunk, and several drifts were driven, but beneficiation to recover the titanium minerals was not attempted. The only successful mining and milling operation of the Magnet Cove rutile deposit was begun in 1932 by the Titanium Corp. of America and continued until 1942. The ore was washed by means of a rotary scrubber and then deslimed in a drag classifier. The discharge was ground in a rod mill, classified, and tabled to recover a rougher rutile concentrate, which was screen-sized and retabled on cleaner tables. The cleaner concentrates were given a reducing roast, screen-sized, and magnetically separated to produce a finished rutile concentrate. Most of the rutile produced during this period was sold abroad. In 1942, the Titanium Alloy Corp. of Arkansas (a subsidiary of the Titanium Alloy Manufacturing Co. of New York) purchased the property and rebuilt the mill. Subsequently, the plant and property were acquired by the Magnet Cove Rutile Co., Inc., of Little Rock, Ark., the present owners. Very little titanium has been produced since 1942. Although the Titanium Corp. activities yielded enough returns to allow continued operation for approximately 10 years, certain factors must be recognized. These are: (1) production of rutile in that period was during a low in the economic cycle which permitted low-cost operation on a small scale, and (2) a considerable portion of the production was above the water level and no drainage problems existed. Prior to this paper there has been no published report of any mineral-dressing investigation of the lower levels of the ore body. Reference is made in another paper1 to an earlier investigation of Magnet Cove rutile by the Rolla laboratory, in which it is stated that recoveries of 12 to 17 pct of the rutile were obtained. The present investigation was undertaken to improve the known milling processes and to provide adequate metallurgical information about the ore treatment. Titanium Technology The titanium mineral of primary interest in the present investigation was the titanium dioxide, rutile. Rutile is one of the industrial minerals whose annual consumption is relatively small but strategically important. The domestic production of rutile was 7100 tons in 1948. The imports of rutile in the same year were approximately 8000 tons.2 A major use of rutile is in the production of welding-rod coatings, for which a product containing a minimum of 92 pct titanic oxide is desired. Other constituents, such as lime, silica, and sulphur, must be held to a minimum, but hard-and-fast specifications for these elements cannot be drawn. It is necessary to incorporate the rutile in a welding-rod coating, make a sufficient number of test welds, and then determine the tensile strength of the weld metal in the as-welded and stress-relieved conditions. Such a test gives

Jan 1, 1950

By W. F., Dietrich

THIS paper deals with the- methods of mining the high-grade clays of California. Although the majority of the clay pits in the state are operated on a scale that is small by comparison with most metal mines, this very fact results in a diversity of methods and gives rise to problems of selection of the method best suited to given conditions. Two or three operators in California produce approximately 500 tons per day of a single kind of clay from a single pit. About five varieties of clay are mined on a scale of 200 to 400 tons per day; not over fifteen varieties are mined on a? scale of 50 to 200 tons per day; and more than 50 varieties are mined at a rate of less than 50 tons per day. It is the aim of this paper to delimit, insofar as the data at hand permit, the conditions and scale of operations that favor the selection of each dominant method of mining that is actually being applied at California properties. Details of the occurrence and utilization of the clays of California have been given in a recent bulletin and are not considered here.

Sep 1, 1928

By T. F. Bower, M. C. Flemings

Results are reported of a study of surface dendrilic structure of an Al- Cu alloy solidified against a chill wall. Most primary and secondary "arms " in the surface dendritic structure are arranged orthogonally, giving the impression of strong preferred orientalion on the surface. However, no such preferred orientation exists and it is therefore evident the arms do not represent (100) directions. The primary arms are shown to be interseclions of a (100) plane wilh the chill plane, or, equally often. the projeclion of a (100) direction on the chill plane. Secondary dendrite arms are usually within a few degrees of 90 deg to the primary arm, independent of grain orientalion. Prirary, secondary, and higher-order surface dendrite arms almost always represenl intersections of (100) platzes with the chill surace, or pvojections of (100) direclions. Growlh of secondary arms is favored on the side of the primary arm where a (100) direclion points toward the chill surfAce a1 a Lou, angle. Surface dendrile arms are often observed to be bent. In these cases, the crystal lallice changes orientation; bending is concave to the chill surface. In a previous paper,' a technique was discussed whereby large grains can be obtained at a chill surface. The technique used involves quickly drawing superheated liquid A1-4.5 pct Cu alloy into a thin copper mold, so that the mold is full well before solidification begins. The chill surfaces employed are polished copper blocks coated with amorphous carbon. Shrinkage during solidification between dendrite arms and grains delineates both, without the need for polishing or etching of the cast surface. The grain structure of the chill surface was discussed in a previous paper;' in this paper, the dendrite arms within each grain are examined. Previous work on surface dendrites includes that of Edmunds, who studied the development of preferred orientation in zinc, cadmium, and magnesium.' In zinc and cadmium, he found that the surface region has a (0001) texture (parallel to the chill surface). Walton and Chalmers reasoned that, since the fast growth (1010) directions are in the basal plane, nuclei which have this plane parallel to the mold wall would produce larger grains than nuclei with other orientations. Hence, the texture observed is as expected.3 The same authors, in measurements on aluminum ingots, found no preferred orientation at the mold wall. However, the X-ray technique they used measured the preferred orientation in terms of grain numbers, not grain areas; larger grains were weighted equally with small ones. No preferred orientation is expected on this basis at the chill surface. In a later paper,' Edmunds stated that experiments show a random grain orientation at the surface in die cast aluminum; his technique, also used in his earlier paper, takes account of grain area. Little work has been published on the dendritic structure of metal chill grains. Recent work of Biloni and Chalmers on "predendritic growth" shows the change in morphology from spherical to dendritic during the initial stages of freezing, 5 but this work did not include detailed examination of the fully developed dendrites. Other pertinent work includes that of Lin-denmeyer, who investigated the growth of ice dendrites. 6 When growth was on a substrate, the dendrite axes were bent. The bend corresponded to a change in orientation of the crystal lattice and occurred in such a way as to align the basal plane to the substrate. DENDRITE STRUCTURE Fig. 1 shows the chill surface of a typical casting poured above the critical temperature necessary to produce coarse grains. A cursory examination of these grains shows that the surface dendrite arms within most of the grains are oriented roughly perpendicular to each other. One is tempted to assume that these are (100) directions and that, therefore, marked preferred orientation exists at the chill face. This, however, is not the case. Each of the grains in the casting of Fig. 1 was separately identified, Fig. 2, and its orientation determined by the Laue back-reflect ion method. Results are given in Fig. 3 and it is seen there that no preferred orientation exists. Even when grain area is accounted for, there is no significant preferred orientation. The relationship between surface grain structure and crystal orientation was then obtained by assigning X and Y axes to the casting surface, Fig. 1, and assigning the same axes to the stereographic projections of each grain. Thus, the visible surface structure could be compared readily with grain orientation. This was done for fifty-five of the grains of Fig. 1. Results of this study on three typical grains are described below, and some general observations given subsequently. Fig. 4 shows the structure and stereographic projection of a grain which lies near the (100) zone (with respect to the casting surface). The X and Y directions are marked on the projection, and the photomicrograph mounted with the same orientation. Poles of the stereographic projection represent crys-tallographic directions in the grain which point out of the casting, toward the chill. Two (100) directions are shown in Fig. 4. A line joining the center of the projection and a pole represents the projection of the pole onto the X-Y plane (chill surface). Two such lines are shown in Fig. 4 (solid lines). A line joining the intersection of a great circle with the circumference of the projection gives the trace of a crystallo-graphic plane in the chill surface; two such traces are shown (dashed lines).

Jan 1, 1968

By R. W. Raymond

(Pittsburg Meeting, March, 1910.) IN the long list of our illustrious and lamented dead, there are names which recall personality as well as career and achievement; social as well as scientific merit; devotion to the Institute itself as well as to some one of the professions which it represents. These men we remember because they did not forget us; besides our pride in their wider work and fame, we are proud of what they did with and through us; especially do we rejoice if our early recognition of them opened the way to a recognition by the world; and in their departure we claim to sorrow, not merely as members of an appreciative public, but also as. bereaved personal friends. In common with thousands, we regret our loss, but we do not regret only-we mourn and miss. To this group of those whose death has brought to us the double sense. of public and private grief belonged our strong, bright, dear brother, in whose memory this inadequate tribute is offered. Charles Benjamin Dudley was born July 14, 1842, at Oxford, Chenango county, N. Y. He came on both sides of New England blood, his father being from New Hampshire and his mother from Connecticut. Emigrating from the rocky hills of their native States, they. settled upon the more fertile soil of what was then regarded as the West, and, with thousands of other pilgrim sons, imitating the pilgrim fathers, contributed to the foundation of new commonwealths. The Empire State owes much to this element of its population. Dudley's early education was obtained, like that of the sons of the pioneers generally, by attending the village school and academy in the autumn and winter, while he worked upon the farm during the rest of the year. But his ambition looked forward to a college-course; and this was almost within his reach when a passion still stronger took possession of him. The out-

Jun 1, 1910

By J. R. Low, M. B. Reynolds, L. O. Sullivan

The effect of neutron bombardment upon the stability of type 347 austenitic stainless steel has been investigated by a magnetic technique. The relation of the ferrite content of a stainless steel to its magnetic properties is given, and an apparatus suitable for the measurement of the ferromagnetic saturation induction of small specimens is described. Results of measurements on irradiated specimens are tabulated. Exposure to a neutron flux was found to cause a slight increase in the ferrite content of type 347 stainless steel, the change increasing with increasing length of exposure and with increasing initial ferrite content. The similarity of the effect of irradiation to the effect of annealing is pointed out. Possible effect of irradiation upon density of austenitic stainless steel is discussed. COMMERCIAL austenitic stainless steels are alloys of iron, chromium, and nickel, plus small quantities of other elements. Although these alloys are normally used in the austenitic condition, this state is thermodynamically metastable at ordinary temperatures and transformation to a more stable state takes place under favorable conditions. In the austenitic state, these stainless steels have the face-centered-cubic crystal structure characteristic of y iron, but the stable state at room temperature is a mixture of austenite and body-centered-cubic ferrite. The transformation from the pure austenitic condition may be brought about by cold working the alloy at a temperature below that at which the aus- tenite becomes thermodynamically unstable (about 400°C), the completeness of transformation increasing with increasing severity of cold work and decreasing temperature. The behavior of the austenitic stainless steels under ordinary conditions of use is rather well known. However, use of these alloys in a nuclear reactor introduces a new variable: the effect of neutron bombardment upon the transformation from the austenitic to the ferritic state. It was with this in mind that a study of the radiation stability of austenitic type 347 stainless steel was undertaken. Magnetic Technique for Ferrite Determination Commercial austenitic stainless steels such as type 347 undergo little transformation under normal conditions of fabrication and use. In view of this fact, it seemed likely that neutron irradiation would change the ferrite content of the alloy but little. The method chosen for measurement of the effect of neutron irradiation was thus limited to one which would be quite sensitive to small changes in the ferrite content of the alloy. Of the properties of the stainless steel which can be measured, the magnetic characteristics are most sensitive to the quantity of ferrite present.

Jan 1, 1956

By P. E. Fitzgerald

SOME readjustments in the research programs of most of the oil companics and petroleum engineering schools have been made necessary by the war. The most obvious change has been the conversion from production engineering to problems more closely related to the nation's was effort. Many laboratories now devote much of their time to studies on products to be derived from petroleum. such as synthetic rubber, toluene, and substitutes for critical materials. Others are working to improve motor fuels including high-octane gasoline and the special lubricants required by the wide geographical range of the present conflict. Of great importance is the experience of the geophysicists, who are now devoting a great percentage of their time on instrument research and production or special apparatus required by the armed forces.

Jan 1, 1943

By Gerhard Derge

EXTRUSION processes are used in the commercial production of a wide variety of products, as indicated by the review presented a few years ago by D. K. Crampton.1 Most writers have confined themselves to a general description of the equipment and products and the engineer-ing aspects of the process. The few studies that have dealt with the metallurgical side of extrusion have been concerned primarily with an examination of the mode of flow of the metal during extrusion. This has been accomplished by the use of composite billets, by scribing grids on symmetrical sections of billets and observing the change of dimensions in the gridwork, or by examining microstructures in extruded sections.2-8 Another limitation of these original studies is that they were confined to the extrusion of very simple shapes, usually rods having a diameter of about one-fourth that of the billet. Tin is particularly well suited to the extrusion of collapsible tubes and similar shapes in which the extruded section is very small in comparison to the diameter of the billet or slug. In modern production, impact extrusion methods are generally employed, therefore the thickness of the slug is small compared to its diameter. Under these conditions the process differs considerably from the processes that have been most fully described in the literature, and it is known that the quality of the product is very sensitive to slight variations in any one of the many variable factors involved, such as composition and structure of the alloy, rate of extrusion, temperature, shape of punch and die. An exhaustive examination of all of the above-mentioned problems promises to produce so many data that it seems advisable to initiate the reports at this time, even though all of the factors outlined have not been examined fully, and to confine this paper to a description of the apparatus and method. Only tin and its alloys with small amounts of copper have been considered. These are the alloys most commonly used in this country for the production of the type of articles already described.

Jan 1, 1939

By W. W. Duecker

SULPHUR is a peculiar combination of a nuisance and a useful element. Most of the nonferrous metallic ores contain large amounts of it in the form of sulphides, which the metallurgist has wasted up the chimney, since the sulphur dioxide formed is generally too dilute to make recovery economical and practical. Iron ore does not contain much of the unwanted sulphur; in pig iron and coke it is most unwelcome. Gold metallurgists can get along nicely without sulphides in their cyanide plants and yet they find matte-a sulphur compound -an excellent collector for gold and silver in base-metal smelting. Also, sulphur appears in the non-metallics as in barite, gypsum, Glauber's salt, and celestite, all to useful purpose.

Jan 1, 1938

By Robert :H. . Lesemann

I recently gave a talk at a seminar on mine development in the Eighties. I had to present CRU' s long-range market outlook for copper, lead, zinc, nickel, molybdenum and silver. In reviewing the recent history of each metal, and our projections, I tried to find some common pattern of behavior that could prove a guide in projecting future market behavior. When you sweep aside your input-output models and econometric equations, what you seem to be left with is this: "When a market goes through a prolonged period of price weakness, you can usually look forward to a period of considerable improvement. " "When a market goes through a prolonged period of price strength, you can always anticipate a prolonged period of price weakness." Stated another way, "The better things are, the worse they will get."

Jan 1, 1982

By JESSE L. MAURY

DEVELOPMENT of new gold mines in Canada since the price of that metal was increased in 1932 and 1933 has been of interest and importance to many of us. The day-by-day story has given an impression of aggressive effort and enough good luck so that the spirit of enterprise has been encouraged. It is the purpose of this article to report the results of a statistical appraisal which give emphatic numerical confirmation to this impression, together with certain side lights on the costs of development and equipment of new mines. The data presented have been taken from all readily available published sources up to the close of 1938 and are representative of that year. A. B. Bower did a large part .of the spadework and Weston Thomas offered many helpful suggestions.

Jan 1, 1939

By John Dodd

This paper reviews advances in the technology of abrasion resistant iron and steels, which could help combat abrasion and wear in mining operations. With the recent progress in high chromium alloy iron development, high temperature heat treatment of massive castings can be eliminated, aloy cost reduced, and cracking problems avoided. Data on erosion-corrosion resistance of these irons; trends in the development of improved cast steels; and factors influencing toughness and abrasion resistance of manganese steels are all considered. The 7% Mn. 1% Mo manganese steels are shown to combine toughness and abrasion resistance, and composite castings are a means of combating abrasion in applications involving severe impact. A brief appraisal is given of recently developed martensitic wrought steels with improved weldability.

Jan 1, 1982

By W. C. Meyer

In an effort to conserve and extend oil resources, the use of powdered coal-in-oil mixtures (COM) as an alternate fuel in oil-fired boilers is receiving increasing attention. For the approach to be successful, some degree of stability of the suspension against settling is needed. The variety of means available to achieve stability of this nonaqueous slurry is reviewed along with some of the physical and chemical concepts which underlie each method.

Jan 1, 1983

By Robert T. Gdagher, Allison Butts

EDUCATIONAL trends as reflected in curricular changes are of interest and importance in engineering educa¬tion both as matters of record and as considerations for the future. The data on which the evidence of this report is based were obtained by sending questionnaires to all schools in the United States granting the undergraduate degree in mining engineering, metallurgy, or metallurgical engineering. The questionnaire had two parts, one inquiring as to the general nature of revisions made or planned, and the other asking for information on specific courses added to or dropped from the curriculum, or given more or less time than formerly. The frequency with which curricular changes are made, even in normal times, is notable. Although it was expected that the period since 1939-40 would show numerous revisions, it was somewhat surprising to find that of 62 mining or metallurgical curricula in existence in 1939-40 and reported in the present survey, 58 had been revised or are shortly to be revised, 52 having already been changed during this period. Moreover, approximately half of the mining schools that have already revised their curricula, and probably a similar proportion of the metallurgical schools, are about to make further important changes.

Jan 1, 1948

By AIME AIME

TRADITIONALLY, the Annual New York Meetings of the A.I.M.E. cover four days, but the program is growing on each end as well as in the middle, and this year it lasted from 3 p. m., Sunday, Feb. 16, when the Education Division got under way, to 8:40 p. m., Friday the 21st, when a trainload of electrical inspectors, pro tern, got back fro111 the General Electric plant at Schenectady. The meeting has ceased to be a mere three- ring circus: on Wednesday afternoon eight sessions were being held simultaneously in the Engineering Societies Building, if one includes the Woman's Auxiliary, and according to frequent testimony one should include the W. A. as one of the most important units in Institute affairs.

Jan 1, 1936