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By W. W. Gerberich, P. L. Hemmings, V. F. Zackay

ThE strain-induced martensitic transformation may be used to attain desirable combinations of strength, ductility, and fracture toughness. One of the parameters is the relative stability of the austenite. For example, it has been shown by Zackay et al.1 that the volume percent of strain-induced martensite is related to the combination of strength and elongation obtained. It has also been shown that the degree of transformation is an important factor in the crack propagation resistance of metastable austenitic steels.2 Considering both tensile and crack-propagation tests, it was of interest to see if there was any functional relationship between the amount of strain and the volume of strain-induced martensite. Previously,9 it had been shown that at room temperature, there was a relationship between uniaxial tensile strain and the volume percent of resulting martensite given by The data were obtained by plastically elongating tensile samples to a certain strain and then measuring the field strength to determine the strain-induced ferromagnetic volume. This was accomplished for two conditions having yield strengths of 229 and 233 ksi. The nominal composition of this material was 9Cr-8 Ni-3 Mo-2 Mn-2 Si-0.25 C-0.09 N. In evaluation of the strain-induced martensite at a crack tip: the question arose as to whether Eq. [1] would also be valid under triaxial stress conditions. Tests were conducted on 1/2-in. thick plate material having a composition of 9 Cr-8 Ni-4 Mo-2 Mn-2 Si-0.27 C. It was found that sectioning, polishing, and etching of fractured specimens could reveal the strain-induced martensite occurring at a crack tip. Care had to be taken to minimize the final polishing steps so as to avoid a smeared layer of strain-induced martensite. The method for taking metallo-graphic samples from fractured crack-line loaded type samples is shown in Fig. 1. Observations of the strain-induced martensite occurring at room tem-

Jan 1, 1970

By Louis A. Panek

Ground movements in the zone adjoining an active cave were measured at four sites in the San Manuel Mine. Measurements were made to detect extension and inclination, basic components of displacement, which can readily be duplicated by mine personnel using relatively simple equipment. The displacements demonstrated the development of a zone of strain relief surrounding the active cave, within which the ground tends to migrate toward the cave, and extension cracks develop tangential to the cave. This expansion of the ground surrounding an active cave can be exploited to promote future caving; it also creates special problems with respect to the design of an effective ground support system for mine openings in the production area.

Jan 1, 1981

By E. W. Davis

THE mysterious Lake Erie price for iron ore, established each spring, determines the maximum price that will be paid during the following season for ore of Mesabi Non-Bessemer base grade. This price is impor-tant to the ore producers, but since most of the ore in the Lake Superior district is owned or controlled by consuming inter-ests, the really important question to them is not the price of ore but how much it will cost them to mine and transport their season's requirements to their furnace plants. However, a few million tons are actually sold each year, and considerable quantities are traded for mixing purposes, and the negotiations for these sales and trades usually begin with some reference to the Lake Erie price. There is no difficulty with the Lake Erie price itself or with the manner in which it is established, but the system prescribed for determining the values of ores that are not exactly base grade is incomplete. The Lake Erie price takes into consideration only the iron and phosphorus contained in the ore, but when the ore producer is negotiating a sale or trade, he is confronted by the fact that his ore must be studied and the price adjusted, not only on the basis of the iron and phosphorus analyses, as specified by the Lake Erie price, but also on the basis of silica, alumina, man-ganese, structure, etc. The vague and unsatisfactory methods used in making these adjustments bear some relation to the manner in which the ore is supposed to act in the blast furnace. The ore producer may not understand all of the idiosyncrasies of the blast furnace, but if the smelting-plant operators have a system more accu-rate than the Lake Erie price method for determining the relative values of different ores, why not pass this information on to the ore producers, so that they can make use of it and perhaps modify their practice in such a manner as to benefit both them-selves and their customers? There is a lack of understanding and appreciation between these two groups that may, to some extent, be unavoidable, but in the interests of efficiency and conservation rules that are more accurate and complete than the Lake Erie price method in use at the present time should be established for the guidance of the ore producers.

Jan 1, 1940

By Pol Duwez, Ellis P. Frink, Paul Pietrokowsky

Ti-Au alloys in the composition interval 0 to 66 213 atomic pct Au have been studied over a temperature range from 400° to 1500°C. A partial phase diagram has been established from micrographic and macroscopic observations. All intermediate phases, Ti3Au, TiAu, and TiAu., exhibit open melting maxima. It has been observed that small additions of gold lower the allotropic transformation temperature of titanium. The P solid solution decomposes eutectoidally to a solid solution plus Ti3Au. The solubility of gold in a solid solution decreases with temperature. THERE have been several papers in the literature pertaining to the alloy system Ti-Au. However, a comprehensive study of this interesting constitu- tion diagram has not been conducted. Previous investigations have been concerned with the crystal structure of intermediate phases or partial phase diagrams. This paper represents a partial constitution diagram, Ti-TiAu,, the first portion of an investigation of the entire binary system. Laves and Wallbaum' reported the intermediate phase Ti,Au to be isomorphous with CuAu, L12 type. In a more recent paper, Duwez and Jordan' have concluded that TiAu has an atomic arrangement which is related to Cr,Si. The intermediate phase

Jan 1, 1957

By Robert M. Dreyer

Population growth in industrialized economies constitutes an automatic stimulus for expansion of the construction and chemical processing industries, which are a big market for industrial minerals. Of the total value of mineral production in the United States, excluding fuels, about 70 % results from the production of industrial minerals. The value of industrial mineral production rose more than 10 % between 1961 and 1962. A similar growth has occurred during 1963. During the decade 1952-1962, the production of industrial minerals increased in value by 98%, in contrast to an increase of 60% in the value of the gross national product. The accompanying table shows the percentage change in the production of various industrial minerals from 1952-1962, as well as from 1961-1962.

Jan 2, 1964

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,' 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 papcrs 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. Arrangc-mcnts were therefore made to present that evidence at this meeting. Material Examined The material exalllined was high-ernission 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 t.horia 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.

By Bernard York, John J. Reed

Mine opening stability was investigated by loading model openings to failure. Eight-inch plaster blocks were cast with small uniform section openings passing through the centers. After curing, the models were jacketed and loaded hydrostatically in a closed vessel. Opening size, shape, and orientation were varied to determine how these factors influence opening stability. THE investigation described in this paper is a continuation of a project begun in 1946 by Bernard York and W. E. Bush. .The experimental method used in the investigation involves the hydrostatic loading of a model mine opening to failure. Most investigators agree that this loading closely approaches actual conditions in very deep mines. The conditions are further idealized by using an essentially isotropic model material. The experiments consist of casting 8-in. plaster cubes, or 8-in. diam cylinders 8-in. long, having a relatively small uniform section hole passing through their centers. After thorough drying, the models are jacketed in a flexible plastic bag and loaded hydrostatically with water in a closed vessel. At about 300 to 500 lb per sq in. pressure the central opening fails. The fracture pattern resulting from opening failure is studied in a plane normal to the longitudinal axis of the opening. The model block is sawed through its center after loading to expose this plane and to eliminate the possibility of end effect. By changing

Jan 1, 1954

By C. M. Nickerson

It is apparent that repressuring of the oil measures is becoming increasingly important to the oil industry, and is a matter that warrants the best efforts of the petroleum engineer charged with applying this method of operation to a producing property. Considerable attention has been directed to repressuring in various California oil fields, such as Dominguez and Seal Beach, which have served to sell the more progressive operator on this idea and also to keep him sold. The projects that have received most attention are in comparatively young fields where the fluid levels are high, the wells, perhaps, still flowing, where the wet gas production is of considerable volume, and where there is vital need of immediate conservation of gas, which otherwise would be blown to the air. The new State of California Gas Law, which prohibits the waste of gas, has served to interest the oil industry in means of conserving the gas that is now being blown to the air because of lack of markets. This vitally affects the operator in the older, well-depleted oil fields of the state, because in many cases he has a limited market for gas, on account of the flush production from the more active oil fields. While the waste of gas is relatively small in these older fields, such as the Midway-Sunset area, it now attains considerable importance, since under the new State Gas Law it must be put to some bcneficial use. Repressuring in the older fields of California has not received the attention of the petroleum engineers that is warranted by the present situation. This paper was prepared with the view of presenting the salient features connected with repressuring in the well-depleted oil measures of the older fields, and to show what results have already been obtained in these fields by injecting the unmarketable gas into the sands, particularly in the Midway-Sunset field in the San Joaquin Valley of California. Other projects in the older fields of the state offer some supporting data in this connection, such as the Shields Canyon and the Brea Canyon fields. Gas Storage and RepressuRing On account of the lack of market for a large portion of the dry gas produced in certain of the older, well-depleted oil fields of California, the

Jan 1, 1930

By Irwin Roman, Thomas C. Serman

It has been known for many years that when a wire is moved in a magnetic field, an electromotive force is developed which is proportional to the rate at which the wire is moved in a direction perpendicular to the magnetic intensity and to the magnetic intensity itself. If the ends of the wire are connected to a current indicator, the current behaves exactly as though the source of electromotive force were a galvanic cell. If a wire is wound circularly and rotated uniformly around a diameter not parallel to the intensity, the current flowing through the wire will be alternating of sinusoidal shape. If, instead of a single loop, there are several turns wound in a short helix, the electromotive force developed will be approximately proportional to the number of turns, the area of the helix and to the speed of rotation. The maximum electromotive force will be developed when the axis of rotation is perpendicular to the field; if this is not so, only the component of the intensity that is perpendicular to the axis of rotation is effective. This is the principle of the usual earth inductor. With a few turns of wire and comparatively slow rotation, it is possible to produce a considerable deflection of a galvanometer. If two similar coils are rotated together at two different points for which the magnetic field intensities perpendicular to the axes of rotation are different, the electromotive forces developed will each depend on its corresponding intensity and be a measure of that intensity. If the intensities are sufficiently different so that the electromotive forces may be compared, the two intensities may be compared. This is the principle

Jan 1, 1934

By H. R. Barnhurst

It would be a difficult matter to trace from the beginning the very few improvements made in the burning of fuels prior to 1860. Donbtless the crossing of the sticks of wood in building a mood fire early appealed to our savage ancestry as a means of expediting its effectiveness for their crude culinary purposes. Stones and andirons came later in assisting the admission of air to the under part of the fuel bed, while beacons and cressets, utilized metal bars as supports for the same purpose. It is probable that Tuba1 Cain owed his success to the use of bellows making possible the use of mixed fuel and charge upon a hearth. With the development of working in cast iron, grate bars came in, and they are still with us doing duty in every household and almost every art where heat is a factor. Little was done beyond these crude methods prior to 1860. With the advancement of knowledge came the fuel-gas producer, a natural child of the retorts employed in supplying illuminating gas. It is only within the last 15 years that the conclusion became general that complicated systems for saving heat would not remedy deli-. ciencies in its primary development, and within that time there has been great advancement in the means of producing initially a fire of high effciency, so that to-day we are moving rapidly toward both high development and high absorption, with the resultant of high efficiencies. In studying the subject of the availability of pulverized coal as a fuel, it may occur to ask, why has this not come up earlier? This, question would be naturally prompted by recalling the fact that Thomas Crompton's English patents upon his methods were issued to him nearly 40 years ago. A conclusive answer to this, however, is that Crompton at that time had very crude facilities for making what was at best a very imperfect pulverization of the coal, arid the expense of preparation mas very great. He does not seem to have been aware of the advantage of a thorough drying of the coal in the

Jan 1, 1914

By J. B. Warriner

Introduction STRIPPING is the name given to the process of removing clay, rock, or other cover from deposits of coal or ore. In this paper it is intended to cover the methods used in carrying on this operation in the anthracite coal regions of Pennsylvania. In doing this, attention will be chiefly devoted to those methods wherein practice in different sections of the region differs, or is susceptible to change or improvement, though it is intended to give as complete data as possible concerning all stages of the operation. The data from which this paper has been prepared have been collected and submitted by a committee representing the larger users of stripping methods, of which committee the writer has acted as chairman. Data and assistance have also been obtained from various mining men, engineers, contractors and manufacturers of stripping equipment, to all of whom our appreciation is clue.

Jan 1, 1917

By C. B. Auel

THE subject of this paper involves the crux of the industrial safety problem. It is not overstating the fact to say that "a plant can be made as safe as the management and the workers want it to be;" if such desire is not in evidence and it is not possible to maintain interest in the work of safety, there can be practically no headway beyond the first few steps. These first steps may be said to embrace simply the mechanical or equivalent guarding of tools and equipment and may be taken in a more or less perfunctory manner; but, it has been estimated, they will not effect a reduction of more than 25 to 35 per cent. in the accidents likely to occur in an unguarded plant. The question therefore may be pertinently asked, "Whose interest is meant in the title of this paper, employers', employees?, or both?" It has been repeatedly stated that no safety work of any importance can be carried on: in a plant unless the employer believes in the value of such work. Such statements are true, but have become threadbare with constant repetition and the public is led to believe, that employers differ from ordinary human beings, that their sympathy for their fellowmen has become dulled, and they can be awakened to a sense of the fitness of things with respect to safety, health, sanitation, working hours, etc. only by legislation. There will undoubtedly be found an employer, now and again, who measures down to such specification; but the speaker, in a number of years of close contact with large employers (and his experience has been duplicated by many others) has found that the employers are usually far in advance of the general public in matters affecting the welfare of their employees, including their safety, and not from a selfish viewpoint, but from the humanitarian, economic, etc. If, at times, there is an apparent lack of headway in the solution of some problem connected with employees' welfare, it is not so much due to indifference or a failure to be awake, on the part of the employer, as it is to a lack of knowledge of the way in which to proceed to its successful accomplishment. Further, employers are, only human and cannot follow. every one of the innumerable matters connected with an industry down to their minutest details; they must delegate certain individuals as their representatives, clothing them with the necessary authority to act. These representatives should be looked upon as the Management in their respective fields and the

Jan 6, 1925

By H. Cecil Spicer

THE results described in this article are based on field work conducted during the periods April-May, 1939, and May-July, 1940. The United States Potash Co. is mining potash on Government land under a permit from the Department of the Interior and the geophysical investigation was completed under a cooperative arrangement made between that company and the Conservation Branch of the Geological Survey. The writer, a member of the Section of Chemistry and Physics of the Geologic Branch, was assigned to this investigation. Four definite objectives were in mind for the geophysical work in the studies over the salt deposits. The first was to determine the measure of success that could be attained in this type of work with the resistivity methods that were to be employed. These methods had been introduced into the work of the Conservation Branch by Benjamin E. Jones for the investigation of dam sites, and have been used under his direction by the author for such work. If the method proved to be applicable, an effort was to be made to contour the top of the salt beds and also the other formation boundaries known to be present in this area. Salt-water aquifers were to be studied in an effort to determine their boundaries, and an attempt was to be made to delineate the potash-bearing beds. EARLIER STUDIES Others have made, and reported, resistivity studies over saliferous deposits in different areas. Friedel1 and Messrs. Schlumberger2 reported geophysical work performed in the discovery of the salt domes of Alsace; Carrette and Kelly3described the geology of the same area. Leonardon and Kelly4 published a resistivity curve obtained over the Hettenschlag dome, and a further discussion of this same area was given by the Messrs. Schlumberger5 in a communication. Messrs. Alty6 described studies on salt deposits in which the single-probe method was used. Sinerez7 mentions that electrical methods were tried over salt deposits in Spain. Geoffrey and Charrin8 show a resistivity curve obtained over marl, gypsiferous marl and salt which is similar to that obtained over the New Mexico salt deposits. Kelly9 reported resistivity work performed with the ground comparator of Zuschlag over the salt deposits near Syracuse, N. Y., where the Salina formation is at a depth of 700 to 8oo ft. Some structural studies on the potash basin of Alsace are described by Poldini.10 Another single-probe resistivity study, made over salt deposits in New Mexico, is briefly described by Heiland,11 through the courtesy of Harry Aurand, of the Midwest Refining Co.

Jan 1, 1941

By Benjamin F. Tillson

Although portable fire extinguishers are valuable for fires in an incipient stage, some medium that will dissipate a large amount of heat is needed to fight a fire in mine timbers, because of the size to which the fire will probably have grown before it is discovered. Scaling off, or otherwise smothering such a fire with gases that will not support combustion, is often ineffective for the residual heat will cause reignition when the area is opened and fresh air reaches the hot charred timber. The most effective ways of fighting mine fires, therefore, are to drown and cool the hot zone with water, and to "load out" the partly burned material. Either of these methods requires a direct attack of water ; upon the inflamed material; therefore, every mine containing a large ' quantity of timber or other combustible should be as completely equipped with a fire-hydrant system as it is with compressed-air mains. Mine managers may object to the expenditure, especially if they have not suffered from mine fires. The cost of such preventative measures, however, is only a small portion of the possible losses, and the water pipes can be used for other purposes, which will pay the carrying charges. They can supply water to the rock drills, which will encourage more wet drilling with hollow-drill steel, for the trouble and expense of packing water to individual tanks at the drills will be removed. The carbon-tetrachloride hand extinguishers seem to have no place in mining except for fires that start in electrical equipment. They give off noxious gas, which may prove poisonous in confined quarters; and as it is heavier than air it is of no value for smothering fires overhead or in side timbers and would be dissipated by a good ventilating draft. The old soda-acid extinguisher or the more modern "foam" types ' are preferable. The former probably does not rely for its efficacy on the carbon dioxide generated but on the smothering and cooling effect of the water and the trajectory of stream that may be obtained because of the gas pressure developed. The production of a foam having a tough film to smother a fire, even on overhead surfaces, with the added

Jan 1, 1923

By Alden B. Greninger

In a recent study1 of the deformation of metastable beta copper-zinc and beta copper-tin crystals, it was established that the parallel markings that appear on the surface of these crystals after slight deformation represent lattice transformations. Stereographic analysis showed that in beta copper-tin, the poles of these markings deviated one or two degrees from poles of the form {133}. In beta copper-zinc the plane delineated by the markings corresponded to no one crystallographic plane of the matrix lattice; the marking poles deviated from 5° to 11° from poles of the form (110), and were displaced only a few degrees from (110) zones. Inasmuch as the new transition lattices produced as the result of the deformation are different for each alloy, it was thought at first that the habits of the markings might be the result of a cooperation between matrix lattice and transformed lattice. (Both matrix lattices arc body-centered cubic.) Such a cooperative effect is thought to obtain in the formation of Widmanstätten figures, for it is well known that the matrix lattice alone does not determine the habit assumed by a segregate phase. On the other hand, it is not inconceivable that the dissimilarity in marking habit might be due to differences in deformation characteristics of beta brass and beta bronze. Barrett and co-workers2 have shown that slip-line habits in pure iron are markedly different from those in high-silicon ferrite; and although it has been repeatedly demonstrated that plates of a segregate phase do not necessarily form on the slip planes of the matrix lattice, deformation characteristics may be more intimately allied with plate formation when a transformation is made to occur as a result of plastic deformation. However, there is the fact that the orientation of markings in metastable beta copper-zinc is the same whether the markings be produced by quenching, deformation, or liquid-air cooling; likewise, quenching and deformation markings in metastable beta copper-tin are oriented in the same way with respect to the beta matrix. During the course of the investigation referred to above, samples of 52:48 (stable beta) copper-zinc were deformed and examined micro-

Jan 1, 1938

By Henry Seltz, Cyril Wells, Hugh J. MacDonald

Several investigators have measured the heat capacity of cementite, using different methods of attack, but the agreement between the values obtained cannot be considered good. Naeserl has made measurements of "average heat capacities" of iron carbide between 1026" and 85" K., using a water calorimeter. His computed true specific heat at 78.1" K. is 11.22 cal. per gram-formula mass, which, if correct, is much too high for any reasonably accurate extrapolation to 0" K. The cementitc used by Naeser was obtained from a steel containing 0.9 per cent carbon, by electrolytically dissolving out the iron in a neutral bath of ferrous chloride. The cementite remained as a coarse, crystalline, gray powder. Andes2 has measured the specific heat of iron carbide, from 102" to 323" K., as it exists in steel. The specific heats of several slugs of steel of known iron carbide content were determined, and the specific heat of the iron carbide (Fe3C) calculated by plotting specific heat versus percentage of carbon, and extrapolating to pure Fe3C (6.7 per cent C). The heat-capacity values for temperatures below 100" K. were obtained by comparing the temperature-specific heat curve for Fe3C to that of Fe. Since the two were very similar in the range examined experimentally and approach more closely at low temperatures, it was assumed that near the absolute zero the form of the curve for Fe3C would be similar to that of Fe. Andes calculates for the entropy of Fe3 C,S298 = 23.55 e.u. The heat of formation of Fe3C has been studied by several workers. Kelley3 has reviewed these measurements and calculations, and selects those of Roth* and Naeser6 as worthy of most consideration. Roth has given AH = 5400 cal. + 30 per cent as a result of his own and other work. Naeser has determined the heat of formation from Fe and different forms of carbon, and for graphite (0) he finds AH = 5600 cal. Kelley accepts the rounded figure AH = 5500 as the heat of formation at 298.1" K., but this value is quite uncertain.

Jan 1, 1940

By K. C. McCutcheon, John Chipman

To a very large extent the quality of a mild steel ingot is determined by the manner in which it is poured into the ingot mold and its behavior during the first few minutes after it has been poured. The formation of the solid rim of metal around the periphery of the mold, the effervescent action of the liquid steel within this solidified rim and the upward or dounward movement of the metal level are indications of what is going on beneath the surface of the liquid metal, especially at the interface at which solidification occurs. Observation of this "rimming action" enables an experienced observer to predict the thickness of the sound skin of the ingot and the location and extent of cavities or "blowholes" caused by entrapment of gases. The control of rimming action at the hands of a skillful steel pourer is a vital part of the control of quality in mild steel sheet, and the behavior of the liquid steel during the rimming period is a useful criterion of the melting and refining practices employed in the open hearth. The behavior of rimming steel during solidification depends primarily upon the evolution of gases from the molten metal and it is therefore a problem of considerable interest to determine the nature and amount of the gases evolved. A number of attempts to determine either the amount or the analysis of the evolved gases have been reported. Klinger,' in 1925, analyzed the gases extracted from rimming, sernikilled and killed steel ingots and found that the chief constituent of the rimmining gas was carbon monoxide. The relatively large amounts of nitrogen reported in his first few samples may have been due to incomplete removal of air from the gas-collecting mechanism. McKune² reported similar studies of rimming ingots from which surprisingly large proportions of nitrogen and hydrogen were evolved. Ameen and Willners3 determined both the amount and composition of gases extracted from unkilled ingots with the aid of diminished pressure. Their ingots weighed only 80 kg. (176 lb.) and apparently were solid within two or three minutes, so that their

Jan 1, 1938

By H. Landsberg

In a previous report1 it was pointed out that a successful attack on roof troubles has to be preceded by extensive scouting. As Lord Kelvin once said, scientific progress can be made only if accurate data are available: "unless you measure, you do not know." The Convergence Recorder For the observation of roof movements in mines the convergence recorder has shown that it will enable us to get some of the necessary information. Results with convergence recorders were first published by Winstanley and other English investigators for rapidly moving longwall faces. In their investigations the speed of work and the heavy overburden produced a considerable amount of absolute values of convergence in a short time. Under the conditions frequently encountered in our investigations in Central Pennsylvania, under shallow, overburden and in mines with slowly proceeding extraction, the movements observed were much less in absolute value, for an equal interval of time. This mas partly because the mines in which our studies were carried on frequently had idle days, sometimes four or five in succession. Therefore continuous records were not employed and a simple convergence gauge was built. In its first models, it consisted only of two telescoping tubes pressed against roof and floor by a coil spring. At the side of the lower tube a rule divided into 1/2-mm. divisions mas fixed and a knife-edge, which was attached to the upper tube, mas slid over the scale in case of convergence between roof and floor. While the larger motions could be read on this device, it seemed to be desirable to increase the accuracy by inserting between the two tubes a dial meter reading in 1/1000 in. Such a gauge was first built in April 1937 and installed for experimental purposes in a bituminous coal mine in Pennsylvania (Fig. I). It was read at least once daily, 24 hr. apart, and if feasible at shorter intervals. After several months of experience it can be said that this type of gauge answers the scientific as well as the practical needs. It is easier to handle than the recorder; no clock is used, there are no pen troubles. The price of

Jan 1, 1938

By Harry T. Davis, Jasper L. Stuckley

The object of this paper is to record and interpret field and laboratory observations made by the writers during five years of study of the barite deposits of North Carolina. Deposits of barite are known to occur in three localities in North Carolina (Fig. 1) two of which—the Hot Springs and Kings Mountain —contain material of economic value. The Hot Springs area begins near Bluff, some 6 miles south of Hot Springs, and continues northeast by Stackhouse; a total length of 7 miles. The Kings Mountain deposits lie along a belt that extends from the north end of Crowders Mountain in a southwestward direction, along the east side of this and Kings Mountain, to Kings Creek, South Carolina. The third locality is 3½ miles southeast of Hillsboro, Orange County, a short distance west of the highway leading from Hillsboro to Chapel Hill. It is not known when barite was first discovered in North Carolina, but production from the Hot Springs area began some 50 years ago. The state has never produced large quantities of barite—usually there have been less than three producers—and definite figures are not available, but reasonably reliable estimates indicate a total production of 300,000 tons. From 1901 through 1920 barite mining was on a seemingly prosperous basis and a large tonnage was shipped from the Hot Springs and Kings Mountain areas. With the depression of 1920 the industry began to decline and production practically ceased in 1926. Geology of the Barite Areas In the Hot Springs area barite is found in the Max Patch granite of Archean age and the Snowbird formation of Cambrian age. The Max Patch granite is of two varieties, one gray to whitish and the other red. The gray granite is coarse, at times porphyritic, and composed of quartz, orthoclase and plagioclase feldspar, with a little biotite and muscovite. The red granite is also coarse and differs from the other only in having conspicuous pink and red feldspar. Both varieties have been much metamorphosed and weathered in places, so that they contain secondary

Jan 1, 1935

By F. R. Morral, E. P. Miller

Hot-dipped heat-treated zinc coatings on sheet steel were examined with X-rays. The phases identified were compared with those listed in the modern literature 01 the zinc-iron system. The zeta (FeZn13) phase is shown to correspond to the phase found by Schueler (1925) in heat-treated zinc coatings. An investigation was undertaken to determine the phases present in hot-dipped heat-treated zinc coatings on steel sheets and wire. This kind of coating on wire was studied some years ago by Schuelerl by microscopic and chemical methods. He reported a new phase, FeZn10. Later, Clark and Stillwell,2 using X-ray crystal analysis, identified a new phase in ordinary galva. nized wire, which was assumed to be the FeZn10 phase. Since the extensive review of the iron-zinc alloys presented a few years ago,3 much new work has been published, some of which5-l6 was too late to be included in the recent edition (1939) of the American Society for Metals' Handbook.4 Figs. 1 and 2 are reproductions of the latest iron-zinc diagram proposed by Schramml1 as a result of his investigations by microscopic, thermal, magnetic susceptibility and X-ray methods. Table 1 summarizes all the known published X-ray data of the phases Present. The solubility of iron in zinc has been determined by x-ray methods.10 In the same manner the homogeneity range of the P phase was studiedlo using the principle that the parameter of an intermetallic compound changes while the concentration of One of the constituents changes. Schramm10 has found some 80 alpha lines in X-ray powder photograms of phase d1, and from these he believes that this phase is related to the P phase. Previous investi-

Jan 1, 1941