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By A. S. Richardson

The design of mine airways receives, in general, very little engineering treatment. To a large extent this is, of course, due to the fact that information upon which to base calculations is seldom available in definite form. In many rnines the extent of the workable deposits may not be known at the time an air course is planned, and the length of service is indeterminable. Volume of air required for ventilation rnay also increase with extension of the life of a property, and natural obstacles, such as heavy ground, often place limitations upon the size of opening that can be maintained. Perhaps most of the shafts used in the ventilation of metal mines were originally intended as hoisting shafts, and many of the tunnels and crosscuts similarly used, were also designed as haulage ways or for other operating purposes. Even when a shaft is sunk solely for ventilation, custom usually dictates a size and shape consistent with the type commonly used for ordinary operations, because experience has demonstrated it can be excavated and maintained. In fact, most ventilation openings were never made with any consideration as to economic design for such use. When an air course is required to pass air between different parts of mine workings under a fixed pressure, the size of opening required for a given volume of flow, is, of course, determined by the resistance factor of the air course. It is then impossible to proportion the opening with reference to economics of power consumption, and this paper is limited to the design of openings where ventilation pressure or power consumption may he varied for economic advantage. As the size of an air course is increased, the expense involved in excavation and support is, of course, also increased, but the charge for power is decreased. In the case of a mine that has only a short assured operating life, it would not be ecouomical to provide large openings in order to reduce power bills; but when operations are likely to continue for a long time, the power charge becomes a very important economic factor. Although lack of definite information on such factors as service life and costs of excavation and support affects the design of an air course, it appears, from a mathematical analysis of the problem, that considerable variations may be made in estimating these factors, without greatly

Jan 1, 1927

By R. E. Ogilvie, H. C. Gatos, R. E. Hanneman

The ejj-ect of high pressures on chemical inter-diffusion in the Fe-V system was determined by analyses of concentration vs distance profiles of atmospheric and high-pressure diffusion couples. Diffusion data were obtained as a function of tern -perature and composition. Activation energies, activation volumes, and frequency factors were determined at 1 atm, 20 kbars, and 40 kbars as a function concentration in the a and y phases. The A great deal of research has been carried out in the measurement and understanding of binary chemical inter diffusion in solids. Studies of the effects of high pressure on interdiffusion in binary systems, however, have been virtually nonexistent until the present work. This paper gives a detailed account of the effect of high pressure on interdiffusion and the Kirkendall effect in the Fe-V system. The present data are compared to existing theo- Kirkendall effects were measured at 1 atm and 40 kbars. At 1 atm Dy > DFe at the marker concentration; however, Dv approaches DFe under pressure, and at 40 kbars the values are approximately equal. The high-pressure and atmospheric diffusion data are evaluated on the basis of theoretical models. Chemical analyses of the diffusion -couple profiles were made using an electron microbeam probe. retical treatments of pressure dependence of diffusion which are based upon self-diffusion studies. THEORY The rates of atomic migration in metals and alloys are regulated by the repulsive forces exerted on an atom during its motion from one equilibrium lattice site to another and by the availability of a jump site. Application of high pressure is expected to decrease diffusion rates because it decreases interatomic distances as well as defect concentrations. A number of theoretical treatments have been focused on the problem of calculating self-diffusion coefficients in solids under atmospheric pressure. In general, the vacancy mechanism of diffusion appears to be dominant at high temperatures in most metallic systems. The migration of an atom by this

Jan 1, 1965

By H. C. van Elst

Ultrahigh-speedphotographic and electronic meth-ods were applied to an investigation of details of brittle-fracture propagation in steel. The brittle fractures studied were obtained in steel plate with the aid of a Robertson apparatus. It was found that a brittle fracture proceeds by discrete steps ranging from 30 mm near the stop temperature to less than 2 mm at lower temperatures. The halting FROM prior metallographic observations of brittle fracture in steel' it could be concluded that the distribution of mechanical twins along a brittle fracture was similar to the distribution of mechanical twins induced by explosive deformation. It was therefore assumed that a running brittle fracture created stress waves, cf. Refs. 2-7. An emission of stress waves by a brittle fracture, however, seems only conceivable if the fracture propagates by discrete steps. For this reason a study of the details of times between successive steps drop in this tem-perature region from 20 usec to about 1 psec. The stepwise propagation mechanism is accompanied by an intermittent emission of stress waves of the order of 100 to 200 kg per sq mm. These stress waves seen1 to play an important role in the mechanism of brittle fracture as will be discussed. brittle-fracture propagation was undertaken to investigate the possible determination of the fracture steps and the emitted stress waves associated with the assumed mechanism. The more practical object of this work is the development of a test method for the determination of the ductile-brittle transition in small specimens. This has special advantages for the study of irradiation damage in steel. In this test method, which will be published in a following paper, the stress waves emitted by an actual brittle fracture are reproduced with explosive or electrical means and are then transmitted through small specimens at various temperatures. In the present paper only the results of the brittle-fracture study will be reported.

Jan 1, 1964

By Lucien Eaton

THE accuracy with which detachable bits can be sharpened and gauged by grinding has made possible refinements in design that cannot be attained by forging. This applies particularly to gauging, where accuracy is of the greatest importance. Gauge changes of 1/32 in., and even 1/16 in., are now feasible, whereas 1/16 -in. changes are about the limit in accuracy for forged bits. These small changes in gauge are feasible, however, only with certain fundamental principles of design. Within reasonable limits the depth to which a hole can be drilled is dependent primarily upon the loss in gauge, or diameter, of the bit. In drilling there is always a certain amount of " overdrilling "-the bouncing of the bit in the hole and its rotation wear away the walls-so that the actual diameter of the hole is greater than the diameter of the bit. The amount of this overdrilling depends upon the kind of rock being drilled, and is sometimes sufficient to permit the use of the same diameter of bit for the full depth of the hole. If, for instance, a 1 ¾ -in. diameter bit overdrills 1/32 in. in diameter, and loses 1/64 in. in gauge in drilling 2 ft. of hole, the bottom of the hole is still 1/64 in. larger than the original diameter of the bit, and a new 1 3/4-in. bit can be used to drill the next 2 ft. If, however, the overdrill is less than the loss in gauge, the next bit must be of smaller diameter. The first requisite in reducing loss of gauge in drilling is to have the points and corners of the wings of the bit cut circles of the same diameter, thus producing a reaming surface with continuous bearing on the wall of the hole. The greater the reaming surface, the less the gauge loss that is to be expected. If the reaming surface, however, is too large, it may impede the rotation of the bit through excessive friction. This principle was probably first recognized in the design of the Carr bit (Fig. 1)) a bit with a single cutting edge of wide angle, a definite reaming edge, and a large center hole. The same idea was followed in designing the double-taper cross bits, which are now standard almost everywhere Fig. 2 illustrates a typical double-taper cross bit. The taper from the point of the wing A to a little behind the corner B is 5° and from

Jan 1, 1939

By S. Weissmann, P. R. Swann, D. F. Wriedt

The sizes and density of precipitates in an intemally oxidized 0.19 wt pct Al-Ag single crystal have been determined by low-angle X-ray scattering and by transmission electron microscopy . The correlation in particle sizes measured by the two techniques is reasonably good. For an oxidizing temperature of 800°C the particles were found to INTERNAL oxidation of dilute alloys of aluminum in silver produces an oxide which has an excess of oxygen compared to Al2O3.' It is believed that the excess oxygen is an indication of the small sizes of the oxide particles. Depending upon the particular model chosen for the oxide structure, the size of the o-A1 particles can be calculated as a function of the oxygen-to-aluminum ratio. These calculations pre- have diameters in the range 30 to 140A, with a mean size of about 50.4 as observed by electron microscopy. At lower oxidizing temperatures, less than 600°C, no clearly resolved particles are formed, and it is suspected that if A1-0 clusters exist they must be exceedingly small, i.e., 10A or less in diameter. dicto that the particles would vary in size from 15 to 100A. This range of sizes is amenable to detection by both small-angle X-ray scattering and transmission electron microscopy. This paper compares the cluster sizes in such internally oxidized A1-Ag alloys determined by transmission electron microscopy and small-angle X-ray scattering. SPECIMEN PREPARATION Single crystals were prepared from 99.9999 pct Ag, obtained from Cominco Products, and 99.99 pct Al, obtained from Aluminum Co. of America. All melting operations were carried out in graphite molds under flowing purified hydrogen in a horizontal zone refiner. The silver was first degassed,

Jan 1, 1964

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. W. Bakarian

PREVIOUS determinations1,2,3 of the texture of magnesium and its alloys have shown only slight variations in the principal features of the structure. This investigation presents pole figures for magnesium and two of its alloys, in which differences of some magnitude will be shown. Schmid and Wassermann have considered the texture of magnesium in analogy with that of zinc-also a hexagonal lattice. Whereas the zinc texture is said to be derived primarily through basal slip and secondarily through {102}† twinning, the {102} twinning is considered impossible at the later stages of the rolling in magnesium because of its smaller axial ratio. This state of affairs appears reasonable for pure magnesium, but for alloy textures the situation is more complex. A double orientation similar to that found in zinc has been reported by J. D. Hanawalt,4 and the addition of small amounts of calcium to magnesium and its alloys to produce a double texture was noted by J. C. McDonald.5 The pole figures of this investigation, using an improved X-ray technique, show these various textures. The dependence of directional properties of rolled sheet on modifications of texture is well recognized. Correlation of physical properties with existing texture should be even more significant if quantitative valuations are attached to the various areas on the pole figures. Such a quantitative technique is developed herein. EXPERIMENTAL METHOD Two alloys were used, besides high-purity magnesium. In each case, the metal was extruded to bars 32 in. thick and hot-rolled to a thickness of about 0.075 in. It had been established previously that such a reduction was more than sufficient to eliminate the extruded structure. The rolling proceeded in the same direction as that of the extrusion, without any cross rolling. The temperatures corresponded to normal commercial practice, averaging around 600°F. A unique method of preparing the sample was developed in this work. Instead of using a flat specimen, a stem of the metal was cut out of the rolled sheet in the desired direction (rolling direction) as shown in Fig. 2. From a sheet of 0.075 to 0.065-in. gauge, the stem was cut to a square cross section with a jeweler's saw, rounded with a file and polishing paper to a diameter of 0.060 in, and evenly etched in dilute hydrochloric acid to a diameter of 0.038 ± 0.001 in. In this way, a cylinder of the original sheet with its axis in the desired direction was produced. By using this type of specimen for the pin-point pictures, any variance in the absorption of the diffracted beam at the various angular settings of the specimen, was completely eliminated.*

Jan 1, 1941

By W. A. Koehler, M. E. Hinkle

INTRODUCTION THE oxidation of pyrites and marcasite in coal-mine strata to produce discolored acid mine drainage has long been explained by chemical reactions occurring in three stages: I. The iron sulphide minerals are oxidized by air in the presence of water to produce a nearly colorless solution of fer¬rous (iron) sulphate and some sulphuric acid. 2. The ferrous sulphate and part of the sulphuric acid combine with additional oxygen to form ferric (iron) sulphate. 3. The ferric sulphate hydrolyzes to form a reddish-brown precipitate and additional sulphuric acid. Nevertheless, chemical data alone are not sufficient to explain all observed facts. The first stage seems to proceed more slowly in the chemical laboratory than in nature. The second and third stages nor¬mally occur to a marked extent within a few days with raw mine water. However, the visible discoloration that characterizes these latter stages will not develop for months if the mine water is sterilized. By means of bacteriological techniques, two organisms have been isolated from acid coal-mine drainage. These are believed to have a part in promoting the chemical reactions summarized above. One organism is considered to be Thio¬bacillus thiooxidans, which is known to be able to convert elementary sulphur or sodium thiosulphate to sulphuric acid. Its relation to the formation of acid mine drainage has not yet been established. Apparently it does not promote the oxida¬tion of ferrous iron compounds in mine, drainage to the ferric state. The second organism has not been identi¬fied by name but is described as "Gram negative, non-spore-forming rods approxi¬mately 0.4 micron wide by o.8 to 1.0 micron long." A pure culture of this when added to sterile mine water will cause the latter to become amber and develop the typical rusty precipitate. However, it has not been found to convert sulphur com¬pounds to sulphuric acid. Further research is planned to determine whether or not these microorganisms play a significant part in the first stage of oxidation whereby pyrites and marcasite minerals go into solution. Some of the conditions found in abandoned sections of coal mines, such as a reduced percentage of oxygen and increased percentage of carbon dioxide in the air, as well as the existing temperature and acidity ranges, will be tolerated by and may even be favorable to these organisms. ACID COAL MINE DRAINAGE Acid coal mine drainage has been the concern of coal mine operators, industrial¬ists, sportsmen and public officials for many years. The amount of acid flowing into our streams in the coal-producing areas varies considerably from mine to mine and from

Jan 1, 1948

By D. D. Button, L. D. Jaffee

INTEREST in the use of graphite as a high-temperature engineering structural material has recently increased markedly. However, actual use of this material has been limited, in part because information about its high-temperature mechanical properties has been lacking. The information needed includes not only reliable values for the properties, but also how to control these properties. Malmstrom, Keen, and Greenl have reported on the tensile and creep properties of some graphites above 2700° F (1500°C). They observed measurable creep under tensile loading at 4000 OF (2200 °C) and higher, with elongations of about 7 pct at 4500°F. Their typical elongation-vs-time curve showed the normal three stages of creep found for many metals at elevated temperatures. The specimens used were heated by passing an electric current through them. This method of heating caused a significant difference between the surface and axis temperatures, and may have affected the results. More recent work by kattus, in which the specfinens were also heated by their own resistance, showed very little plastic deformation for either slow or fast tensile testing or for creep testing. Work at this Laboratory, already reported,3 showed that for temperatures above 4500 "F and under conditions of slow tensile loading some commercial graphites exhibited elongations up to 20 pct. The work reported here is the continuation of a study of the tensile creep behavior of some commercially available synthetic graphites at temperatures up to 5300°F, and is preliminary to a more systematic investigation of the variables governing the high-temperature mechanical properties of graphite. MATERIALS TESTED The tests were conducted on six blocks from four lots of synthetic graphite bearing four different commercial-grade designations. These blocks were selected because their tensile stress—strain properties had been determined in previous work.3 Table I pre- sents the available information, supplied by the producers, on the processing of these materials. Also included in this Table are the densities and the tensile strengths at room temperature and 4500°F determined by the authors. EXPERIMENTAL TECHNIQUE The furnace used to heat the specimens for testing is shown in Fig. 1. The heating element was a graphite tube, 3-in. OD by 2 1/2 in. ID by 24 in. length. A spiral was cut into the 6-in. center portion of this tube to provide a high-resistance sec-

Jan 1, 1961

By T. E. Ockershauser

The Southwest Antioch Oil Field located in T2&3N - R2&3W, Garvin County, Okla., was discovered in February, 1946, by The Globe Oil & Refining Co. and The Vickers Petroleum Co. at their Melinda Gibson No. 1. Oil production was encountered at a depth of 6,525 ft in 14 ft of lower Pennsyl-vanian sandstone. The producing sand, locally called the ."Gibson" or "Third Deese," is a sand bar deposit strung along the west flank of the Pauls Valley uplift in a northwest-southeast direction. The oil reservoir is defined to the east by the edge of sand deposition along the uplift and to the west by the gradation of sand into shale. Within the Antioch Unit, the sand dips from 150 to 400 ft per mile southwesterly and has a pay thickness varying from 10 to 55 ft and averaging 28 ft. Several areas of Gibson production have been developed, including the Katie pool on the south, the Elmore Area of the Southwest Antioch Gibson Sand pool. the Southwest Antioch Gibson Sand pool proper, the Southwest Maysville pool and the New Hope pool on the north. Production extends over a belt 22 miles long by about two miles wide and is continuous except into the Katie and New Hope pools. It appears that drilling will soon prove these intervening areas productive. To March 1, 1950, approximately 18,000 acres have been developed with 450 Gibson wells. It is likely this count will ultimately reach 32.000 acres with 800 wells. RESERVOIR The natural production of oil from the Gibson reservoir is primarily due to solution gas expansion though gravity also plays a part. There is no indication of water drive or evidence that an initial gas cap existed. Gibson oil has a stock tank gravity of 43" API and was saturated at the original reservoir pressure of 2.925 psi. It contained 1,3440 cu ft of gas per bbl in solution and had a high shrinkage of 70 per cent. Connate water amounts to 15 per cent. Reservoir temperature is 130°F. Porosity averages 15.5 per cent and permeability ranges from less than one md to over 1.000. Based on meacurement of 400 core plugs from 15 wells, 78 per cent of the permeabilities fell within the 10 to 1,000 md bracket and averaged l67. Primary oil recovery is estimated at 140 bbl per acre-ft or 22 million bbl for the present 137-tract unit. Due to unitization

Jan 1, 1951

By Helmut Thielsch

DURING the last three decades a great many arguments have been presented on the subject of "mosaic" or "block" structures of metals. Apparently because of insufficient evidence, the "block-structure" theories have never been widely understood among the physical metallurgists in this country, and most investigators among the few that have tried to demonstrate the existence of such an inner structure of crystals or grains have failed to recognize also the existence of a lamellar structure. Moreover, little thought has been given to justify the existence of such "lamellar" or "mosaic-block" structures on a theoretical basis. Since properties such as plasticity, ferromagnetism, hardness, diffusion, and others may be explained by structural faults in the lattice network of the crystals, the great importance of a more detailed knowledge of the structure within crystals or grains becomes now evident. Because of the vast extent of the field of submicroscopic structures, it shall be the purpose of this paper only to review the more important of the results obtained by other investigators, especially in Germany, where a great deal of attention has been given to mosaic structure during the last three years. The origin of this mosaic pattern f and effects of cold reduction and recrystallization will be shown in further studies later on. IMPERFECTIONS IN CRYSTALS The many terms used in the literature to denote structural types of crystals are often not clearly defined. To clear up some of the confusion, the meaning of the more important terms will be given here. Ideal, or Perfect Crystals.-Crystals without any structural imperfections are called "ideal crystals," or "perfect crystals," meaning a homogeneous interior structure of atoms, ions or molecules, as the case may be. In other words, at every point in the interior of the crystal exactly the same orientation of the crystallographic axes of the coordinate system would exist. The surface of such a body, if etched with an appropriate etching reagent, would reflect light with perfect uniformity. Crystals of this type are almost nonexistent. Real Crystals.-" Real crystals"' may contain various types of structural defects, which can be classified into: (I) lineage structure, (2) mosaic-block structure, (3) lamellar structure. The inhomogeneities existing in these groups mean that the orientation of the crystallographic axes will not be the same at every point within the interior of a crystal (or grain of a polycrystalline body). Perfect Real Crystals.-The term "perfect real crystals" is generally used to describe crystals with minute structural or thermodynamical inhomogeneities. The former

Jan 1, 1945

By H. O. Hofman, H. L. Norton

Zinc smelters in the central western States have established a very high standard of purity for blende-concentrates, viz., zinc 60, iron less than 3, and lead less than 1 per cent. The very low percentage of iron is made possible by the blende containing less than 0.5 per cent. of isomorphous iron sulphide and by the sparing occurrence of pyritic material in the large blende-deposits of southwestern Missouri and southeastern Kansas. The blende in these districts occurs in sub-carboniferous limestone, and is associated with chert, residual clay, cal-cite, pyrite or marcasite and bitumen. The different minerals are coarse and therefore readily separated by mechanical washing from the blende, with the exception of pyrite and marcasite, as blende has a specific gravity of from 3.9 to 4.1; marcasite, from 4.85 to 4.90; and pyrite, from 4.95 to 5.10. The common procedure of dressing the ores' is to crush in a breaker, size in a trommel with 0.5-in. holes, pass the over-size through roughing-rolls and then jig the ore, now reduced to 0.5 in. maximum size, in roughing multiple-sieve jigs. The products of these are waste-tailings, side-discharge coarse concentrates, side-discharge coarse middlings and bottom-discharge fine middlings. The coarse concentrates are sent to the market. The coarse middlings are crushed in middlings-rolls and brought back into the system by feeding into the main trommel. The fine middlings are cleaned upon finishing-jigs. Any pyrite or marcasite present follows the blende and increases the percent- +1MASSACHUSETTS INSTITUTE OF TECHNOLOGY, BOSTON, MASS.

Jan 1, 1905

By Robert H. Richards

(Read at the Wilkes-Barre Meeting, May. 1877.) THE Institute of Mining Engineers has shown so much interest in the educational problem of profitably combining theory and practice, that it seems especially appropriate to lay before its members the methods and aims of the mining laboratory of which I have charge, and in which one form of combination of hand with head work is now being tried. If anything may be contributed toward the solution of this problem by the discussion which follows, my purpose will be attained. Whether it was wise or not to establish a mining school so far from the principal mining centres, does not now enter into the question. Given, a mining school already begun, how shall it be made most efficient in developing engineers who are trained to think for themselves as well as versed in the works of others? This is the ques¬tion with which we have had to deal. In considering the bearing of this laboratory work upon the students' preparation, it will be convenient to take it up under five different heads 1. The methods and aims of the laboratory. 2. The advantage to students of having a part, at least, of their practical work in the curriculum of their school. 3. The advantage to be derived by mines and works. 4. Degree of accuracy which may be attained in working ores on a small scale. 5. Results of work in the laboratory. 1. The Methods and Aims of the Laboratory.-During the May meeting of 1873, held in Boston, I had the privilege of reading before you a paper stating the plans and aims of this laboratory. Since that time we have been constantly following out those plans, and are more than ever convinced that we are working in the right direction. We do not feel that the time we have spent has been in any sense thrown away. Perhaps the aims of the laboratory can be most clearly shown by illustration. Many young engineers leave school thinking that they know everything. They go to the works, and expect to teach the superintendent something and the men a good deal, regardless of the fact that it is this spirit that has prejudiced workmen against schoolmen. They are often more trouble than they

Jan 1, 1878

By Ancel St. John

AT THE New York meeting of the Institute of Metals Division in February, 1927, Jeffries and Tarasov presented a paper on Tungsten and Thoria,1 in which the experimental facts were interpreted in accordance with the prevailing point of view that the thorium is present as the oxide, thoria. In discussing that paper the writer of this article stated that his own investigations, which had been unavailable to Messrs. Jeffries and Tarasov, showed that the so-called "thoriated" tungsten filament failed to disclose any sign of the oxide when subjected to X-ray diffraction analysis, but did give plenty of evidence of the presence of metallic thorium and, in certain cases, of a material believed to be an alloy of tungsten in thorium. Since these results were completely at variance with the results reported in the paper under discussion and with other papers which had preceded it from time to time in the past, it was felt that further discussion should be withheld until the new evidence could be presented adequately. Arrangements were therefore made to present that evidence at this meeting. MATERIAL EXAMINED The material examined was high-emission filament such as is used in radio tubes, supposed to contain about 0.75 per cent. thoria. The actual analysis was not stated. SCOPE OF THE INVESTIGATION The investigation was undertaken because of a feeling that the thorium present in filamentary material of this type exists as metallic thorium or as an alloy of thorium and tungsten and not as the oxide. Attention was therefore directed to determining: 1. The minimum amount of thoria detectible in a mechanical mixture of thoria powder and finely divided tungsten. 2. The amount of thoria detectible in the filament. 3. The condition of any thorium present in other form than as thoria. 4. The amount of thorium dissolved in the tungsten.

Jan 1, 1928

By J. Donovan Jacobs

An underground excavation project usually is a highly organized complex of different but interrelated construction activities. It is the whole effort, including the necessary tools, which will be referred to as the System. Tunnel-driving and shaft-sinking operations are among the most systematic of construction efforts. Systems are not new in the performance of construction. It is the Systems Concept which seems only recently to have been discovered and made the subject of much study and discussion. HISTORICAL From the seventeenth century, when explosives were first utilized for rock excavation, until the successful application of the rotary-head continuous tunneler in this decade, the cyclical drill-blast-muck-support method has been standard tunnel-driving procedure throughout the world. Whatever improvements occurred were the result of development of better tools for performing the various operations of the cycle. The electric locomotive replaced the mule and permitted the use of larger muck cars. The steam drill, which ended the day of the double jack, was itself quickly made obsolete when compressed air replaced steam as the source of drilling energy. Power shovels were introduced to save the time and money involved in the hand-loading of excavated materials. A cubic yard of rock tunnel muck can be excavated today for just half the man-hours of labor required in 1948. Developments over 20 years which cumulatively have resulted in this economy include: drifter drills mounted on hydraulically controlled booms and positioners; tungsten-car- bide-tipped bits; long feed shells on the drifters, making it possible to drill the full depth of a round without changing steel; better designed,

Jan 1, 1970

By Lester C. Uren

Today, a dozen or more universities and colleges in the United States are offering curricula designed for the specialized training of engineering students who plan to enter the petroleum industry. Many hundreds of students are following these curricula in their academic preparation, with the expectation that by so doing they will be better equipped to enter the petroleum industry in an engineering capacity than their competitors that seek to do likewise with training of less specialized character. Those who have helped plan and develop these curricula believe that such specialization should and does afford the student a superior preparation for his task. Others have questioned this and urge a broad preparation in fundamentals without specialization. Still others are suggesting even greater specialization than present petroleum engineering curricula afford. Some would have the student first prepare himself in one of the more general divisions of engineering, such as civil, mechanical or electrical engineering, and then seek some degree of specialized preparation in a graduate program. Which of these views is correct; or, if there is merit in each, which plan offers the greater advantage to the student? It is time that we paused to take stock of our objectives and of our way of attaining them. Is the training received by our petroleum engineering students what it should be? To what extent is the product of our petroleum engineering schools meeting the requirements of the industry? How may graduates be better equipped for the work they are called upon to do? These are questions that educators interested in the training of petroleum engineering students are ever asking. They must depend upon engineers and executives engaged directly in the industry for advice and helpful suggestions in better planning the training to be offered to our future engineers. This paper will have served its purpose if it is successful in focusing attention of men active in the industry on some of these educational problems, to the end that the ideas of men close to the needs of the industry may be made known to those who have responsibility in the control of our educational programs.

Jan 1, 1937

By R. E. Wade

THE Butte, Anaconda & Pacific electrification is of peculiar interest, in an incidental way, to the entire mining fraternity, and especially the engineering branch, not only in this great Northwest country but throughout the entire Western mining country, which is rich in minerals and water power. It is probably fair to say that the prime object of mining and smelting engineering is to reduce the cost of production, and in the case in hand the relative location of mines and smelter brings the cost of transportation of ore to the front. While some might assign this item to the railway people, it is inseparably a part and parcel of the general scheme of the production of metal from the ore. In considering the electrification of the B., A. &. P. railway the mining and smelting engineer, above all, wants to know what saving will be effected by the change in motive power. Unfortunately the new power has been in use during a very limited period and on the Smelter Hill section of the road only, and no reliable data, from actual service conditions, can be obtained until the entire electrified section has been in service for a reasonable length of time. Any remarks on this subject at the present time, therefore, must of necessity be general in nature and more or less descriptive. The railway, electrical and mining worlds and the country in general are indebted to the B., A. & P. railway for the pioneer work it is now doing, as it undoubtedly marks the beginning of the electrification, within the comparatively near future, of all transcontinental roads between the Missouri river and the Pacific coast. Together with this goes the development of an untold wealth in water power and all natural resources within the same territory. For the first time in the history of electric railway work, in this country, direct current at a potential of 2,400 volts is being used. With this potential there is a great saving in transmission of energy to the locomotives and there are only two substations, one at. either end and 26 miles apart, for supplying the power for the movement of trains of heavy tonnage over the main line and for switching movements at terminal and intermediate yards, and comparatively little feeder copper is required.

Jan 11, 1913

THE second part of the mould for making guns is the core. Without this the space could not be made where the powder is to be and through which the ball, impelled by the fire, can pass and take flight. To make this it is necessary to take two things into consideration, because they are very important. One is what you are to make it on so that it may be supported and kept true. The other is what composition of clay will stand up during casting and yet not be very difficult to extract from the body of the finished gun. For the first, it is found that only an iron spindle of a suitable thickness is able to support the weight of the clay without bending under the heat of the fire or wobbling as it is turned on its journals or when handled. This should be a braccio or more longer than the mould of the gun and worked exactly round, straight, and well tapered like a spindle; above all every one of its joints should be well secured and solid. At the upper end a per-orated heel should be made, and lower down, exactly at the point corresponding to the length of the mould, are one or two other holes through which the little crossbars can be passed that fasten the core to the outer mould and also serve for constructing the disc. Now this iron is to be arranged on two trestles, pivoted so that it may turn truly when rotated. In order that it may not run up and down, make a little iron fork which engages a notch made with a file at the foot, and another at the head. After this, you must prepare clay for the core which is well made and tenacious ,enough not to crack. Fint take care that there are no pebbles in it and that it is composed of a small amount of cloth clippings and much sifted horse dung and some washed and clean wash ashes so that it may be of a tender and crumbly consistency in order that it may later be more easily extracted from the space inside the gun. In the same way, in order that you may be able to take out the iron piece at the same time, first cover it with ashes, and then wrap it all over with a rope of ordinary thickness, leaving a dito of the iron uncovered in every palmo length. [86] Alternatively, you may cover it all very tightly with hemp tow in the same way after it has been covered with ashes. Or heat your iron considerably and then cover it all to the thickness of a good cord with wash ashes or powdered charcoal that has been made into a paste with a little

Jan 1, 1942

By Philip Drinker, R. M. Thomson

In the mining and metallurgical industries, numerous problems arise requiring determinations of solid and of liquid particles suspended in air. Frequently, these problems are of local interest and involve purely economic or operating difficulties; on the other hand, toxic effects from the inhalation or the ingestion of substances suspended in air may be a matter of concern. For checking up process improvements or for determining ventilation efficiencies in problems of this general nature, various methods have been proposed. .Although simpler methods are often satisfactory, precipitation combines several desirable features that other methods lack. This paper is, therefore, devoted to a discussion of portable alternating-current precipitators applicable to the quantitat,ive determination and microscopy of dusts, fumes, and smokes in air. Small particles suspended in gases, such as air, are referred to in the literature as aerosols or suspensoids. Of these terms, suspensoids appears to be preferable as being more nearly in keeping with words in everyday use. In problems involving air pollution by small particles—by suspensoids—it is convenient to distinguish three broad classes based on the size, the degree of dispersion, and the method by which the particles become suspended in the air. Dusts.—Particles or aggregates of particles, 150 to 1 micron in diameter, that are thrown into the air by mechanical agencies are termed dusts. Examples are silica; talc; cement; organic dusts such as hard rubber, starch, and cocoa; flocculated fume, and smoke products. Fumes.—Particles, 0.2 to 1 micron in diameter, formed from chemical or physicochemical reactions are known as fumes. Examples are ammonium chloride, lead and mercury, zinc and magnesium oxides, fogs, and acid mists. Smokes.—Particles, less than 0.3 micron in diameter, formed by incomplete combustion of carbonaceous and other substances are called smokes. Examples are the particles formed from burning tobacco, oil, tar, and gas.

Jan 1, 1925

By J. O. Betterton, W. K. Noyce

I~JTI HE work on the indium-zirconium system is part A of a larger investigation of zirconium-phase diagrams with solute elements, silver, cadmium, indium, tin, and antimony, which is intended to provide information about the metallic valency of zirconium. The system is an ideal example since the sizes of indium and zirconium atoms are nearly the same, and the solute and the solvent occur in the same row of the periodic table. The only solute from Group III B which had previously been added to zirconium was aluminum' and it was of interest to determine whether indium would dissolve appreciably in alpha zirconium and stabilize this phase in the same manner. Experimental Procedure The experimental methods used in the indium-zirconium work are similar to those described earlier for the silver-zirconium system.' Reactor Grade 1 iodide zirconium of 99.95 pct purity* and indium of 99.99 pct purity were arc cast, and then annealed in silica capsules with protective foils of zirconium and molybdenum. Annealing temperatures and times varied from 1 day at 1300°C to 43 days at 550°C. The compositions of the alloys were detcrmined by an individual chemical analysis of the actual metallographic specimens after two or more sides were examined to insure the absence of solute segregation. Calibrated thermocouples were used throughout, and the uncertainty in the temperatures reported, owing to calibration error, furnace control, and measurement of the small temperature gradients near the capsules, is believed to be well within ±2°C. Typical impurities in the alloys were found by a neutron-activation analysis of four different alloys. The results are given in Table I where the ranges of values will be seen to compare favorably with the usual values for iodide zirconium. With respect to oxygen, nitrogen, and carbon the absence of any unusual amount of these elements compared to iodide zirconium was indicated by the alloy hardness values, since hardness is increased sharply by the presence of these elements. The value for 0 pct In, obtained from the alloys by extrapolation, is 58 2 7 VPN which is in the low part3 f the normal range of hardness found in iodide zirconium. Results of the Experiments The zirconium-rich portion of the indium-zirconium phase diagram from the annealing experiments is shown in Fig. 1. Indium was found to

Jan 1, 1959