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W. L. Saunders, New York, N. Y.:—Mr. Parker's paper, though entitled Conservation of Coal, might also be called the Conservation of Life in the Coal-Mines of the United States. No subject is of greater importance to mining-men at the present time than information from experts as to how to save coal and how to save human lives in mines. That the casualties in the coal-mines should exceed 3,000 in the year 1907 is simply appalling, and that 1,000 men should have been killed in a single year through explosions alone, and that so good an authority as Mr. Parker should say that " a prolific cause " is an "improperly-prepared blast" or "the failure on the part of the miner to undercut his coal," points to the importance of activity not only among mining engineers but also, through experts, by the legislatures of the respective States. There is but little doubt that nearly all the serious coal-mine

Jan 1, 1910

By Harry H. Power

INDUSTRY has the right to expect the petroleum engineering schools to supply more than the minimum technical qualifications necessary to obtain or discharge the responsibilities of a particular job. The basic training, social and economic orientation, should go far beyond these minimum requirements. Petroleum engineering students should also be well grounded in the history of the oil business so that they may understand the industry's progress since the advent of the Drake well. Furthermore, according to P. H. Bohart, the schools "have a definite duty to help the students form a workable philosophy of life, which includes an appreciation of the service of science to mankind, and a belief in the obligation of the individual who enters a profession to exalt himself by continuing his studies and growth so that he may never cease making contributions to the advancement of science and industry."

Jan 1, 1948

By AIME AIME

THE technical material in hand and the plans under way for the 141st meeting of the Institute clearly indicate a well-rounded program of unusual excellence. The meeting will be held in the Engineering Societies Building, Feb. 15 to 18, and while it is too early to announce definitely the time of the various sessions much of the detail has been organized up to that point. Every group in the Institute membership will find much of special interest, and several features should prove generally attractive. The various committees in charge of the lighter side of the meeting are hard at work to emulate the standard established last February In this connection and in this paragraph it will suffice to say-there will be a Smoker-dinner! The Committee on Mining Methods plans two sessions for which these papers are in prospect:

Jan 1, 1932

By E. J. Eisenach, W. E. Jones

SAFETY and industrial hygiene have always been recognized as highly important in company policy, and the co-operative support of the company officials and entire plant personnel has contributed largely to the present success of the Company's program in this field. Growth has necessarily been slow, and dependent, at times, on trial and error but the program in its present form combines the regulations, working methods, and equipment that have proved their value under actual operating conditions. Every effort is made to keep the program on a practical basis. Continuous experimental work is carried on in conjunction with the health and safety program, with resultant periodic changes for improvement. As a proof of accomplishment, in 1945 the frequency and severity rates for accidents were the lowest in the history of the operation. A full-time safety engineer was employed in 1933 and an assistant safety engineer in 1936. During the following year a stenographer was employed in the office and a safety inspector was added for the mine. During the gradual expansion of operations that was climaxed by

Jan 1, 1946

By Norman Weiss, H. W. Kaanta

CUSTOM ores reach across the New Mexican mesa to American Smelting & Refining Co.'s new lead-zinc mill at Deming. The influx of ores justified increasing mill capacity from 12,000 tons per month to 20,000 tons per month with the installation of a second milling section. Deming mill has met a complex material handling problem with the successful instrumentation of modern machinery and knowledge. A tight, compact plant does a big job with the aid of the latest ore moving equipment. Location and Layout The mill is located three miles northwest of Deming in the tumbleweed covered valley of the Mimbres River, 30 miles north of the Mexican border. Deming has a population of 4000 and is about halfway between Lordsburg and Las Cruces and 54 miles southeast of Silver City. The AT&SF and the SP railroads and U.S. Highways 70, 80, and 260, cut across the mesa to the town. Asarco mill station is east of the AT&SF single track, and north of Deming. The nearly level terrain is covered with fine sand supporting only yucca and tumbleweed. Compacted gravel at depth affords excellent foundation bearing. The climate is semi-arid, but the district is underlain by water-bearing strata. Tailing disposal space is plentiful. The Deming site appeared favorable because of easy rail and highway access, central location in a mining district, excellent climate, plentiful water supply, space for all present and future requirements, and proximity to a town. The milling plant is a 250-ft square. The rail spur forms the west side; sampling plant, fine-ore conveyor and bins are on the east; track hopper, primary conveyor, and crushing plant lie on the south; and the mill building completes the north side of the square. Construction The mill site was chosen and the land purchased in 1,946 and 1947. Design began in 1948, and Stearns-Roger Mfg. Co. of Denver started construction in June 1949 completing work in April 1950. Construction is steel and concrete throughout, with main concrete floors supported on cellular steel beams. The building is covered by galvanized corrugated iron, attached to the frame by welded Nelson studs, and made dust tight at the joints with roofing paper and asphalt sealing compound. Crushing and Sampling Custom ores, delivered to the mill by railroad cars or trucks, are weighed on arrival. A Robbins car shaker dumps the ore into a 100-ton capacity steel hopper. Adjacent is a 40-ton truck hopper. Three 36-in. Pioneer apron feeders supply ore from the receiving hoppers to a 36-in. conveyor which runs to the crushing plant. A tramp-iron detector protects the primary crusher except when handling magnetite containing ores. A 2 ½ -in. spaced grizzly precedes the primary Traylor 24x36 in. jaw crusher set at 4 in. A Symons 4-ft cone crusher in closed circuit with 48x78 in. Robbins Gyrex screen completes crushing to 5/8 in. The discharges of both crushers drop upon a common conveyor, which, after gaining sufficient elevation, transfers ore to a return conveyor. This return conveyor passes under a suspended magnet and over a magnetic head pulley to the Gyrex screen. Screen undersize is conveyed by a 20-in. belt to the sampling plant. Crushing rate varies from 60 to 90 tons per hour. Ores containing magnetite and pyrrhotite nullify the magnetic detector and overload the magnets

Jan 1, 1952

By Strathmore R. B. Cooke

On the basis of experiments con- ducted on quartz using a bubble pick-up method, it was shown in an earlier paper1 that this mineral will preferentially adsorb hydrogen, calcium, or sodium ions, depending on the relative concentrations of those ions in the solution in which the quartz is immersed. For quartz particles ranging in size from 0.2 to 1 mm, it was demonstrated that the concentration of calcium in solution (assumed present as ions) necessary to completely activate quartz for flotation is given by the expression: In this expression, ionic concentrations are in mols per liter. It was further shown that the pick-up method is apparently more sensitive to changes in reagent concentration than the standard captive-bubble method, and that induction times are apparently much reduced. Since completing these earlier tests, a new type of cell has been constructed; this is shown in Fig 1 and 2. In Fig 1, A is a ground joint, B is a ceutral tube reaching to within a few millimeters of the bottom of the cell, and C is a stopper which may be removed for re- agent addition, and serves the further purpose of excluding carbon dioxide from the air during the test. The entire cell is constructed of Pyrex glass, and does not give the trouble experienced with the earlier cell, in which activating ions were released from the glass at high pH values. The only critical factor in the construction of the cell is the clearance between the central tube and

Jan 1, 1949

By W. J. Schuster

Safety in coal mines depends largely upon adequate training of the foreman. Although management must provide modern and safe equipment and at all times keep mines in first class condition from a safety viewpoint, final results will be determined by the quality of supervision. HANNA COAL CO., Division of Pittsburgh Consolidation Coal Co., operates three large underground mines in eastern Ohio. The section of Pittsburgh No. 8 coal seam in which these mines are located varies in thickness from 52 to 64 in. It is immediately overlain by a stratum of shaly material 12 to 15 in. thick locally known as draw slate, which is structurally very weak and which disintegrates rapidly upon exposure to atmosphere. Immediately above the draw slate as it is normally found is a band of extremely high ash material 6 to 12 in. thick known as roof coal or rooster coal, and above this is a stratum of conglomerate material varying from 4 to 10 ft in depth. Overlying the conglomerate is a relatively thick stratum of limestone, the first stable material above the Pittsburgh coal seam in eastern Ohio. With the method of full-seam mining that has been adopted, draw slate is shot down, loaded with the coal, and removed in the preparation plants. The roof coal then becomes the permanent roof. The major problem in mining the No. 8 seam in eastern Ohio is control of the roof. Since the strata above the draw slate contains no material with a structure firm enough to provide self-support, the roof begins to sag in a relatively short time after the coal and draw slate have been removed. The problem thus becomes one of getting temporary safety posts under this roof as quickly as possible to prevent a break or separation from occurring either in the roof coal or in the conglomerate above it. Haulage System The Pittsburgh No. 8 seam in eastern Ohio is relatively level, with only minor local dips. Throughout the Hanna Coal Co. mines, entries are generally 12 ft wide. Rooms are driven on a 60" angle on 30-ft centers and are 22 ft wide. No attempt is made to extract the 8-ft pillars between. The entire length of main line haulage is gunited in one mine, and a major portion in another. Two of the mines have single-track main haulage roads with passways. The third, a new mine, is double-tracked, and the roof is supported by steel crossbars, 60 lb or heavier, spaced on 4-ft centers and lagged. In recent years timbering on main line and secondary haulage roads has been accomplished by one of two methods: 1—crossbars are supported on a small section of post set in a hitch hole in the rib, or 2—or a hole is drilled in the rib about 12 in. below the roof, of sufficient depth to fasten securely a short length of 40-lb rail, the bottom of the rail facing the roof, on which a short post is set directly under the crossbar. At present the hitch-hole timbering method is favored. At two of the mines the main line haulage locomotives are 26-ton, 8-wheel units. These locomotives are of the axleless type, each wheel being individually mounted on the frame. The motorman's compartment is encircled by 3-in. armor plate for the protection of the occupants. At the third underground mine conventional 15-ton locomotives are being used. However, these locomotives have been completely rebuilt in the company's shops. Equipment has been streamlined and quarters have been provided for two people, who are protected by heavy steel plate in much the same way described above. This modernization program has been completed on all secondary haulage locomotives at the three mines, and the company is well on the way to similar equipment of the 6-ton section locomotives. The following additional features have been included in their modernization: 1—additional support for the motors to prevent their falling to the middle of the track and derailing the locomotives should a break occur in the suspension bar support; 2—installation of additional bracing to prevent brake rigging from becoming displaced and causing derailments; 3—enclosure of all electric wiring in conduit or raceway; 4—provision of an enclosed compartment for the storage of re-railers, jacks, and other equipment, so that they need not be carried on the outside of the motor; and 5—redesign of the end of the locomotive opposite the operator's compartment to prevent anyone's mounting from that direction. It is interesting to note that some

Jan 1, 1955

By C. K. Leith

THE purpose of these conferences has been to find some basic principles to guide us in the chaos which confronts us, to arrive at elements of a national policy. None such exists, nor, as a matter of fact, have there been any concerted efforts by the public or the mineral industry to evolve one. In the absence of such a policy the administrative agencies of the government can hardly be expected to be consistent or really effective in their handling of mineral problems, domestic or foreign. Basic Facts MINERAL reserves are unequally distributed among the nations. The principal world supplies are grouped around the north Atlantic, and nearly three-fourths of the world's total is controlled politically and commercially by English-speaking people. No one nation has a complete supply of the minerals necessary for modern industry; specialization, reciprocity, and large-scale movements between the nations are inherent in nature's unequal distribution of them. The principal sources of supply are relatively few compared with the nations to be served-a fact which determines broadly certain natural outlines of the world flow. National isolation with regard to minerals can be accomplished only through backward steps in industry and lower standards of living even in the nations possessing the most of the mineral supplies. A certain measure of unified commercial control, international in scope, is a natural consequence of the limited number of the large sources of supply. Mineral supplies for the world as a whole are so large that there is little need for concern about early exhaustion, but every nation has important problems of early exhaustion of particular minerals, which must affect their policies.

Jan 1, 1933

By Archibald Macmartin

THE Königin-Marien-Hütte is the only works in Germany where the Bessemer process is carried on by the direct method. The Besserner plant there, is arranged after the true English type, and the only resemblance to the Swedish mode of procedure is the dispensing with the use of spiegeleisen at the end of the "blow." In a new department of the establishment, started within three years, each of the converters is turned by means of a very neat and compact reversible engine, the steel shaft of which is an endless screw, which turns against the oblique cogs of a large wheel attached to the shaft of the vessel. An advantage which this arrangement possesses over the ordinary English hydraulic arrangement, is the fact that the endless screw suffices to turn the vessel, in either direction, any number of complete revolutions; while even the latest American improvements, so clearly explained to us by Mr. Holley at the opening session of this meeting, do not secure even one complete revolution without changing the angle of inclination of the hydraulic piston. In the endless screw arrangement, there being no limit to the working of the motor in either direction (no return-stroke necessary), the vessel can always, unless outside reasons demand the contrary, be turned around to any desired position by the shortest cut, whether backwards or forwards. Also, the diameter of the cog-wheel attached to the vessel can be made sufficiently great to avoid all unevenness of motion. In the old department the motive-power still continues to be hydraulic. If reports be true, the new department produces spiegelized steel, for the manufacture of all-steel rails. But the old department is still,' as from the beginning, devoted to the production by the direct method of steel for steel-headed rails. The most remarkable fact connected with this direct steel is the ease with which it welds to the iron' of the rail-packets, although no borax or other fluxing agent is used to facilitate the welding. It is very rarely that an exception occurs, and an ingot or a charge is discarded by the rail-mill. The mixture of pig-iron used for the production of this steel is melted in cupolas of very interesting construction (not to be de

Jan 1, 1874

By Paul A. Taylor

MUCH information concerning pegmatites which was thought to be true a few years ago has been proved false, and what is now actually known about some pegmatites is not true of many others. The erratic and seemingly unpredictable structure and variable composition of this class of mineral deposits has been widely emphasized. Even parts of the same pegmatite body exhibit marked differences in texture, mineral composition, width, and attitude. Constructive geological thinking in respect to pegmatites now aims to establish general laws rather than to stress the confusing diversity of features having no special economic significance. Substantial progress has been made in classifying different types of these deposits according to general features, internal structure, mineralogy, and origin. In some cases it has even been possible to block out tonnage reserves in advance of mining. It is still easy, however, to make highly erroneous predictions after a preliminary examination of a pegmatite prospect. Pegmatites are important to the economic well being of the country and to its military security. They furnish virtually all the feldspar, strategic mica, beryl, columbium, tantalum, and caesium utilized in the United States, as well as sundry other minerals and significant amounts of lithium and rare earth minerals and gems. With the exception of vermiculite, occasional ilmenite-rutile, and perhaps soda-lime feldspar and garnet deposits, basic pegmatites are of little economic importance. Consequently in this paper, as in common parlance, the term pegmatite generally relates to coarsegrained acidic rocks or what is aptly called giant granite. Available data indicating the size and importance of the production and trade in specified pegmatite minerals are summarized in Table I. Geological Features Much of the latest thinking on the economic geology of pegmatites is now available in a 115-page monograph' by a group of experts who participated with geologists of the Federal Geological Survey in the widespread wartime investigations. Doubtless the most significant feature of the monograph is indicated by the title, The Internal Structure of Pegmatites, but it also contains a vast amount of other new information and includes the assimilated concepts of many earlier writers, whose works are given in a comprehensive list of references. The shape, size, attitude, and continuity of many pegmatite bodies is controlled by the structure of the older rocks in which they occur. If the older rocks are easily penetrated, e.g., biotite schist, most of the pegmatites in a given district will be found outside the parent granite mass as exterior pegmatites. Marginal pegmatites are more prevalent if the older rocks are massive, unsheared, and sparingly jointed. Networks of pegmatites are abundant in highly-jointed rocks. In strongly foliated schists the bodies are usually lenticular, whereas in highly-folded areas they assume tear drop, pipe or pod-like, bow-shaped, or sinuous forms. Jahns2 recognizes five major shape classes: l—dikes, sills, pipes, and elongate pods; 2— dikes, sills, pipes, and pods with bends, protuberances, or other irregularities; 3-—trough-or scoop-shaped bodies with or without complicating branches; 4—bodies with the form of an inverted trough or scoop; and 5—other bodies, including combinations of the above and miscellaneous shapes. Many pegmatite deposits are scarcely big enough to be recognizable as such. Most of them, in fact, are small tabular deposits less than 4 in. wide and usually without economic concentrations of minerals. On the other hand, some pegmatites are more than a mile long and over 500 ft wide. The ratios of length to breadth range from 1 : 1 to 1 : 100. Although the vertical dimension bears no invariable relationship to strike length, tabular deposits or large lenses are often symmetrical enough to show nearly as much continuity down dip as in their horizontal extension, and some pipes or pods are amazingly persistent in the vertical plane. Small pegmatites often string along a fairly definite trend line; in a given district major bodies may lie roughly parallel, and where only a few of them do not, the erratically disposed bodies generally differ in composition from those conforming to the regular pattern. This does not apply, however, in all districts. Characteristically, pegmatite veins pinch and swell or split into branches. When they pinch out entirely it is often possible to find a new body by prospecting the extension of the strike or dip, but the chances of finding a hidden deposit are ordinarily too uncertain to justify much subsurface prospecting. Diamond drilling may yield valuable information as to the continuity of known deposits whose upper portions are well-exposed. Some deposits, in fact, can be proved up for hundreds of feet by surface trenching and then intersected by drill holes at various depths like any other vein-like deposit. Others twist and branch, apparently defying all efforts to explore them short of actual mining.

Jan 1, 1954

By AIME AIME

ON May 5, the Washington, D. C., Section, A.I.M.E., devoted its meeting to the many-sided and perplexing question of mineral stock-piling for peace. Opening the symposium, Harry J. Wolf, of the War Production Board, outlined the problem under six heads: (1) Technical. Mechanical, chemical, or metallurgical importance of specified materials, emergencies that might arise, relative scarcity, and critical value of stock piles during emergencies. (2) Economic. Cost to Government, influence of Government stocks on commercial relationships and markets, effect of availability of items as a con¬structive influence on industry, Administration policies now and during postwar period. (3) Legislative. Need for immediate legislative action, need for legislation on postwar conditions as well as on current requirements, a constructive basic policy to prevent political manipulation. (4) Military. Consideration of re¬quirements and supplies bearing on national safety and needed for manufacture of equipment, and adequate reserves of scarce materials for research or experimentation by military agencies. (5) International. Interests of the United Nations in contradistinction to those of the United States; effects of nonisolation policy on nature, location, and administration of stock piles. (6) Negative stock-piling. Question of United Nations' legislation to prevent stock-piling by Axis nations after the war and who shall purchase stock-pile materials and during what periods.

Jan 1, 1943

By John V. Beall

One Sunday night last month the phone rang and it was George Schenck from Penn State. How would we like to see a big scrap operation, he wanted to know. A few days later we were on the Connecticut turnpike headed for New Haven to visit a large scrap operation, M. Schiavone and Sons. George had a large clam basket in the back which he explained was for collecting trophies. The car shredder, he said, turns out some fancy metal shapes. In fact, they have gained a certain acceptance as objets d’art among George's friends and relatives. He thinks there may be a small, but possibly lucrative secondary market for shredded cars in the art world if the idea is imaginatively promoted. On the way to New Haven we received a briefing on the scrap industry. The scrap business grew from humble beginnings. Mostly it was started by a few immigrant Jews who collected junk in hand- or horse-drawn carts. The fortunate one might even have had a truck. Before proceeding further, we hasten to point out that the word "junk" is strictly taboo among scrap people, who prefer to refer to their industry as the "secondary metals industry."

Jan 1, 1970

By C. F. Jackson

THE work of, the Mining Methods Committee is now well under way. Following discussions previous to and during the February meeting, an Outline for Papers on Mining Methods was prepared, and over a thousand copies have now been distributed to committee men, to section secretaries and to members who have indicated any interest in the subject. The objective of the committee is to prepare a symposium on mining methods which will be of real practical value to the operator and engineer in the solution of every-day mining problems. It is planned to cover the entire field of mining in such a way that the different branches of mining, such as coal and ore (iron, copper, lead, zinc and precious metal) can benefit from the experience of the others at points where they have problems in common.. It is realized fully that each of these branches of mining possesses its own peculiar problems, but at the same time, there are prob-lems in connection with each, where the experience in others should be of value. The committee proposes to proceed along the following lines: 1. To present a general classification of mining methods, showing their inter-relationship, and at the same time .provide a common language for the discussion of mining methods and a nomenclature that will have the same meaning wherever used. A com-plete set of illustrations will accompany the classi-fication to make clear the terminology adopted and to show graphically the inter-relationship of methods. 2. To show the relationship between the physical characteristic of the deposit, the economic consider-ations and the. mining method., It is not proposed to treat this subject as a mere academic problem, but to secure reports from every mining company of impor-tance in this country, which will show what methods or modifications and combinations of methods have actually been applied and the physical conditions and economic considerations which have led to the adoption of these methods in each case. The Mining Methods Committee has drawn up an Outline for Papers on Mining Methods to be distributed among mining engineers and operators, giving in detail the information desired. This outline is the result of several months of careful thought and is a composite of the suggestions of many engineers and mining company officials from all parts of the United States.

Jan 7, 1922

By AIME AIME

EUGENE McAULIFFE will be the fifty-ninth man elected President of the Institute. Looking back to the first President, David Thomas, and reading Dr. Raymond eulogy of him, written eleven years after lie had served his term, we cannot help but feel that Mr. McAuliffe is much the same type of man. Like Mr. Thomas. Mr. McAuliffe takes office in his middle seventies the first President was 76 and our new chief will be 75. Dr. Raymond said A Mr. Thomas: " .. those of us who attended the first few meetings of the Institute ... will bear witness that his indomitable agility, activity and

Jan 1, 1941

By A. Lubinski, C. R. Stewart, K. A. Blenkarn

Storage porosity has been considered one of the important pore geometry characteristics of heterogeneous-porosity limestones. Storage pores are only containers for fluids, in contrast to flow channel pores which both contain fluids and provide continuity for fluid flow. The concept of another geometry characteristic, "poro-striction", is presented as a second pertinent variable in describing limestone pore space. In simple terms, poro-striction is a measure of the flow resistance between storage and flow channel pores. Alternating-flow core-testing theory provides flow relationships which can be used to divide the pore space of heterogeneous-porosity media into flow channel and storage pores and to measure the "porostriction" of the latter. Experimental application of this theory to naturally occurring heterogeneous limestones shows that "porostriction" and the ratio of storage to flow channel pores can be estimated. Porostriction and porosity ratio are microscopic characteristics which should influence oil-recovery efficiencies during certain types of displacement processes. A knowledge of pore geometry should be valuable in designing or selecting the most effective oil-recovery process for heterogeneous limestones containing storage porosity. INTRODUCTION The primary and secondary recovery of oil from limestone (carbonate) reservoirs has been and will continue to be a major source of the world's supply of petroleum. Oil recovery from this type of formation is strongly influenced by the size, shape and arrangement of the pore spaces which hold the formation fluids. Therefore, it is expected that better knowledge of pore geometry would lead to design of more effective recovery processes. The concept of storage and flow channel pores has been presented as an important characteristic of limestone porosity.1 In this concept, storage pores are only containers for fluids, whereas flow channel pores are those pores which both contain and transmit the fluids. The work reported herein involves the concept of an additional pore characteristic called "porostriction". This characteristic can be visualized as the flow resistance between the storage and flow channel pores. This resistance is an important pore geometry characteristic because it determines how easily gas and oil can replenish fluids removed from the flow channel pores. Fatt and co-workers at the U. of California have studied the effect of storage porosity and a factor similar to porostriction on transient-flow response of models of porous media during a pressure build-up or drawdown test.55 These models consisted of porous sandstone cores with artificially simulated storage pores. It is the purpose of this paper to describe tests which permit the storage porosity and porostriction of actual reservoir core samples to be estimated. The tests used for this purpose involved not transient tests but, rather, an alternating-flow technique in which pressure and flow are varied according to a sine-wave relationship. This technique may offer advantages over transient methods. THE POROSTRICTION CONCEPT Before discussing alternating-flow (A.F.) tests in core samples, it is necessary to define the porostriction parameter. For this purpose attention is focused upon an elemental volume v representative of a porous medium having both flow channel pores and restricted-access storage pores. For such an elemental volume, it is considered that the storage porosity is combined to form a single pore and that the access into the storage porosity may be represented by a single capillary tube connecting the single pore to the flow channels of the elemental volume. Let the radius of the capillary tube be designated as Rc and its length as L,. When fluid flows into or out of the pore, the following equation (Poiseuille's law) relates flow rate q to pressure drop p, and the physical characteristics of the tube and the fluid of viscosity jx.

By Jean Herenguel

THE published work of Lacombe and Beaujard' has demonstrated the interesting application of etch figures to the determination of crystal orientations in aluminum by a purely micrographic method. The geometry of these figures leaves no ambiguity and the method has the added advantage of being applicable to very small crystal units. These authors applied the technique to the study of high purity aluminum, and it has now been adopted buy Heren-guel and his collaborators to various researches on commercial aluminum, containing up to 1 pct Fe and Si. This must modify the opinion point,ed out by

Jan 1, 1953

By Harry C. Wiess

RECENT announcement of further restrictions on gasoline consumption in the Mid-West and Southwest has focused public attention on current discussions of an oil scarcity. Conflicting arguments are advanced on the one hand that we have plenty of oil and will not need to restrict consumption as soon as transportation facilities are adequate, and on the other hand that a great impending shortage will require most drastic reductions in civilian consumption in order to provide adequate supplies for military purposes. Data can be presented to support both views, the result being that the public is confused and uncertain of where the truth lies. For a nation with about half of the known crude-oil reserves of the world and two thirds of the total production it seems almost incredible to the layman that any shortage can exist. Those familiar with estimates of future demand. however. show increasing concern regarding our ability to meet military demands without further restrictions in civilian use or wasteful production from our remaining reserves. Only by considering such facts as are available and can be made public can a true appraisal be made of whether or not we are faced with a shortage that will amount to a crisis in crude oil.

Jan 1, 1943

By J. O. Brittain, N. R. Adsit

A number of zinc bicrystal specimens with the grain boundary loaded in simple shear were plustically deformed in creep in a vacuum at 200°C and under an argon atmosphere at 350°C. The results indicated that the amount of grain boundary sliding at a given time was controlled by the slip in the grains and was proportional to the resolved shear stress on the slip plane. Curves of grain boundary sliding vs time were found to be cyclic with no regular periodicity. ALTHOUGH grain boundary sliding (G.B.S.) has been investigated in a number of different types of tests on various materials there is substantial disagreement on the interpretation of the various observations. Gifkins1 has presented a comprehensive review of the subject of G.B.S. and fracture. He reports that the activation energy for high-temperature creep is equal to that for volume self-diffusion and that pure metals show less tendency towards intercrystalline fracture than alloys. Pure metals show appreciably greater grain boundary migration than alloys, and both grain boundary migration and grain boundary sliding follow the same general trend in time as plastic deformation during creep.' While there have been a number of different mechanisms proposed to account for G.B.S., none of the models explains all the results. Since zinc has only one prominent slip system, it was hoped that experiments on G.B.S. in zinc bicrystals might enable us to separate the effect of grain boundary angle and the effect of matrix slip and thereby resolve at least one part of this complex phenomenon. EXPERIMENTAL PROCEDURE Bicrystals of pure zinc (99.99 pct) were grown by a Bridgeman technique in a furnace having a gradient of 20°C per in. The bicrystals were seeded to a desired orientation and grown in a split graphite mold which was 3/4 by 5/8 by 8 in. The mold was enclosed in a Pyrex tube and the tube was evacuated and then filled with a small amount of argon before it was placed in the furnace. The growth rates were 1/2 to I in. per hr for the bicrystals and 1/2 to 3 in. per hr for the single-crystal seeds. The longitudinal V notches served to hold the grain boundary in position during the growth process. A schematic rep- resentation of a specimen which had been cut with a jewelers saw from the bicrystals is shown in Fig. 1. All specimens of a series were cut from the same crystal, some of which were 7 in. in length. After specimen preparation the boundary was approximately 5/16 in. long and the V notches had a radius of 1/16 in. The boundaries were straight at a magnification of X100 with the exception of a few which had a gradual radius of curvature of greater than 3.2 in.-1. Laue back-reflection photograms were taken on the specimens to check the orientation of grains in the bicrystals. The method of relating the orientation of the two lattices is shown in Fig. 1, where 0 is the angle between normal to the boundary and the trace of the basal plane, is the angle in the boundary between the trace of the basal plane and a line parallel to the V notch, and x is the angle in the basal plane between the Burgers vector and the perpendicular to the grain boundary. After mechanical polishing the specimens were chemically polished.2 Subsequent to the polishing operation the specimens were encapsuled under a vacuum of better than 25 annealed at 340°C for 1 hr to remove the effects of this handling, and again chemically polished. Finally, fiduciary marks were scribed on the specimen using a micromanipulator. Creep tests, which were conducted in a modified Bausch apparatusS with the boundary loaded in simple shear, were run at a constant load (since the boundary area remained essentially constant this is approximately constant grain boundary stress). The temperature was controlled to ±1/4°C as measured on a semiprecision potentiometer with a calibrated thermocouple. The specimens were tested in a vacuum of better than 0.5 at 200°C and in purified argon at a pressure of 1/2 atm at 350°C. The op-

Jan 1, 1965

By C. A. Pierce

UNDERGROUND operations of the United States Potash Co. at its mine near Carlsbad, N.M., have been continuous since the property was opened about five years ago. Approximately one million tons of potash has been mined and two shafts have been sunk, each to a depth of about 1000 ft. Outstanding in the company's operations is the fact that not a single blasting accident has occurred during the aforesaid period. The purpose of this paper is to describe the blasting practice that has made possible the achievement of this accident-prevention record. The mining method employed in extracting the thick horizontal bed of potash may be described as a double-entry room-and-pillar system. Mine development is kept well in advance of extraction operations, and a three years' supply of ore, at least, is always available. Limits of the orebody have not been determined, and in the present system of mining headings are advanced by a "shortwall" method. This was the first potash ore bed developed in the United States. The nature of the deposit, therefore, was unknown, and it was deemed expedient to outline a conservative mining policy. Later, when more is known about the deposit and certain control ascertained, a "longwall" panel retreating method may be found advisable. The necessity for a domestic supply of potash became a national issue previous to and during the World War. The United States Govern-ment came to realize that this country should not be dependent upon foreign sources of potash, and began extensive explorations in many parts of the country, seeking an orebody that would meet the exacting require-ments of the domestic market. The Department of Interior, through the Geological Survey and Bureau of Mines, made every effort to determine the location of potash deposits and encouraged their exploitation by private capital. Through the combined efforts of the Department of Interior and private industry, the deposit now being worked by the United States Potash Co. was discovered and brought into production.

Jan 1, 1936

Jan 1, 1949