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By D. Turnbull, J. E. May

THE (110) [001] texture in silicon iron is of considerable interest both from the technological and scientific points of view. Its occurrence was reported more than 20 years ago.1-4 The texture develops by means of secondary re crystallizatjon5 and can be very strong, that is, greater than 90 pct alignment even thouh the primary re crystallization texture is weak or complex. This behavior is in contradistinction to the face-centered metals which develop their strong secondary recrystalliza-tion texture from a strong primary recrystalliza-tion texture.', The microstructural changes accompanying the (110) [001] texture formation in silicon iron are as follows: When properly prepared cold-rolled sheet (i.e., 0.015 in. thick) is annealed at about 800°C, primary recrystallization occurs and a fairly stable fine-grained primary recrystallized matrix of about 0.02-mm-diam grain size is produced. The material at this stage does not have the strong (110) [110] texture. As the temperature is raised to about 900°C, relatively large grains appear in the finegrained matrix and they grow at the expense of the smaller grains to many times the sheet thickness. In time the complete sample is consumed by these large grains. This process of the growth of relatively few grains (about one in 105 primary grains) at the expense of many grains is called secondary recrystallization. Since all the secondary grains are of essentially (110) [001.] orientation, the strong texture is developed by this secondary recrystallization process. Theories of the (110) [001] texture in polycrystal-line silicon iron have been proposed by Decker and Harker and by Dunn.Decker and Harker have shown that grains initially in the (110) [001] orientation will upon annealing after cold-rolling, re-crystallize back to the initial orientation. To account for the sharp texture in silicon iron they propose that (110) [001] grains become more highly strained than grains in other orientations and therefore recrystallize first. They are then the lowest energy grains and can consume their higher energy neighbors. Grains in orientations other than (110)

Jan 1, 1959

By L. F. Coffin

Monotonic tension and controlled cyclic-strain tests have been conducted on an annealed steel at various strain rates and temperatures in the weep range. Evidence of a strain-induced precipitate reaction abozle 500°C was determined from pronounced cyclic-hardening effects, increase inflow stress, inter granular fracture, drastic decrease in low-cycle fatigue resistance, and loss in tensile fracture ductility, as well as through electron-microscopy examination. It was found that strain rate as well as temperature had a pronounced effect on these observations. A parameter of the form P = T(7.95 - log ip) was determined, which was directly related to the ductility, defined either as the true strain at fracture in the case of simple tension, or as 2N 1/2 ? E p in the case of cyclic plastic strain. A highly satisfactory comparison of the cyclic life as measured and as computed from the ductility predicted by this parameter was obtained for a range of temperatures from 400° to 650°C and for crosshead speeds of 0.002 to 0.2 in. per min. MANY metals subjected to sustained loading at elevated temperatures derive resistance to creep from solid-state reactions of various alloying constituents. These reactions can be many and varied, and occur as a consequence of time and temperature according to reaction-rate principles. Strong evidence exists that many of these reactions are influenced by plastic strain, the argument being put forth that dislocations act as sites for nucleation and growth for the new phase.' Many examples can be cited where plastic strain during transformation influences the structure, and as a consequence affects the properties.2 The low-alloy steels serve as particularly good examples for investigating the effect which aging reactions have on resulting properties. Alloying elements such as carbon and nitrogen, and carbide formers such as manganese, chromium, molybdenum, and so forth, can, by the particular aging reaction which occurs, produce strengthening effects at various temperatures, and so endow strength to the alloy over a broad range of temperatures. These effects have been systematically studied by Glen both during creep3 and for constant strain-rate tension testing.4,5 The work of Glen is of considerable interest in connection with the present study, particularly in regard to the effect of various alloying additions on the true stress-strain curve and on fracture ductility at various elevated temperatures. He has shown that strain-age hardening occurred during plastic straining, which was quite specific both to the temperature of the test and to the alloying element involved. When strain-age hardening was noted at a particular temperature, a .minimum in reduction of area was also obtained. Provided the temperature for the minimum reduction of area exceeded 300°C, all minimum ductility fractures were found to be inter-crystalline in nature. For carbon steels containing molybdenum, two minima in reduction of area were noted, one occurring at 200° to 250°C, the precise temperature depending on the percentage of molyb-

Jan 1, 1964

By J. L. Walter, W. R. Hibbard

A GREAT deal of work has been done on the rolling of single crystals of iron. Barrett and evensoon studied end orientations of heavily cold-rolled iron crystals and found that some crystals maintained a sharp single orientation during rolling. Others rotated into two or more orientations, and some fragmented and approached the entire polycrystalline texture depending on the original orientation of both the normal and rolling directions. Barrett, Ansel, and Mehl2 studied iron-silicon alloys and found that the addition of silicon to the iron had little effect on heavily rolled polycrystalline material. Dunn3 has extensively studied the cold-rolling and recrystallization of silicon-iron single crystals. Dunn found that for single crystals having initial orientation between (110) [001] and (111) [112], the principalcomponent of the cold-rolled texture is (111) [112]. Koh and Dunn4 studied the cold-rolled textures of single crystals having initial orientations in the range (001) [110] to (111) [IT01 and found that these are stable end orientations. They also found that all orientations having a [110] direction parallel to the transverse direction rotate to either the (001) [110] or the (111) [112] stable end orientation except for orientations near (112) [11], which divide and produce a final texture consisting of (001) [110]and (111) [112] components. Crystals having a (111) <112>-type texture re-crystallized to a (120) [001] or (110) [001]-type texture. Crystals having orientations with a range of (001) to (335) in the rolling plane and [110] in the rolling direction recrystallized5 to a wide spread of the initial orientations resulting from a multiplicity of 30-deg rotations about several (110) poles. The present study was undertaken to relate other orientations of crystals of silicon-iron to their cold-rolling and recrystallization textures, so that one might rationalize polycrystalline recrystallization data on the basis of the known deformation texture and the behavior of single crystals in these orientations. PROCEDURE Samples were obtained from a cylindrical ingot of 3 pct silicon iron prepared as follows: Armco iron was melted with high-purity silicon flakes under an atmosphere of argon to minimize oxidation. The alloy was poured into a special mold to form an ingot which consisted partially of large columnar crystals. Plates were cut from the columnar portions of the ingot with the longitudinal direction parallel to the columnar axes and ground to 0.040 in. thick. The plates were heavily etched to a thickness of 0.032 in. to remove the cold-worked surface. Orientations of seventeen crystals were determined by Laue back-reflection techniques keeping the mean columnar axis as the reference direction. The plate was then cut in two, parallel to the columnar axis. One portion of the plate was rolled at room temperature parallel to the columnar axis to a reduction in thickness of 84 pct. The remaining portion of the plate was rolled also at room temperature across the columnar axis to a reduction of 66 pct, at which point the crystals began to separate at the boundaries. After rolling, nine individual crystals were removed from the strip by cutting along the crystal boundaries with a jeweler&apos;s saw. Fig. 1 shows the original orientations of the six crystals that were straight-rolled and of the three crystals (4, 7, and 8) that were cross-rolled. Each rolled crystal was carefully etched to approximately 0.002 in. thick. Textures of the cold-rolled crystals were determined by use of the diffractometer with a non-integrating sample holder. The pole figures were made for the (200) poles using molybdenum Ka radiation and were plotted by an automatic stereographic projection recorder.&apos; Spurious poles were determined by rerunning portions of the pole figures using strontium oxide to filter out the Ka radiation. The central portions of the pole figures have not been determined. The pole figures were completed to about 55 deg from the periphery at which point the sample holder interfered with passage of the beam. Following the determination of the cold-rolled

Jan 1, 1959

By R. C. Padfield

Experience over a 3-year period in Bethlehem Steel Corporation&apos;s plants has demonstrated the reliability of open-hearth roofs of bonded sprung-arch constructzon with burned basic brick. The design principles lor constructing these roofs include a minimum hot-strength requirement for the basic brick, expansion allowances that extend the full roof thickness, structural members to control arch contour, and a specified minimum roof rise. The greater stability of bonded roofs is explained in terms of the basic stress patterns of ring constrution and bonded construction. PRIOR to the development of successful sprung-arch roofs of basic brick, the majority of open-hearth furnaces in the United States were operated with sprung-arch roofs built of silica brick. Although many silica roofs used on open-hearth furnaces were ring-arch construction, Bethlehem Steel Corp. used bonded-arch construction because of its greater stability. In ring construction, each ring of brick is separately keyed and comprises an independent arch with the straight joints between rings traverse to the longitudinal axis of the furnace. In bonded construction, the bricks are laid in rows starting from the skewbacks so that the straight joints run parallel to the longitudinal axis of the furnace. Each brick in a given row is laid so that it spans the joint between two bricks in the row beneath it. Thus, the transverse joints across the arch are broken and the arch rings are thereby interlocked or bonded. When basic roofs were first being developed, the basic brick that were available had low hot strength. Such brick could not be safely used in sprung-arch construction without some means of suspending them. With the development of higher firing techniques by brick manufacturers and the recently introduced direct bonded bricks with high hot strength, the use of burned basic brick in sprung-arch roofs became feasible. The availability of high hot strength basic brick coupled with the potentially lower cost and proven stability of bonded construction prompted Bethlehem&apos;s Research Department to study the possibility of using basic brick in bonded roofs. With the full cooperation of plant ceramic engineers and open-hearth superintendents, particularly in 3 years of fur-nace trials, we developed the design criteria for bonded roofs and the corresponding property requirements for the basic brick that are discussed in this paper. DESIGN PRINCIPLES OF SPRUNG-ARCH BRICK ROOFS Stresses in Fixed Arches. A sprung-arch open-hearth furnace roof is generally built on rigidly held skewbacks. The constraint of the fixed support at each end adds a bending moment to the horizontal and vertical reactions at the ends of the arch. Fig. 11 shows the positive direction of forces acting on an arch fixed at both ends. Fixed arches can be analyzed when the members are continuous and have elastic properties. However, brick are inelastic, and arches built with individual brick segments cannot carry tensile stresses. Therefore, for practical solution of brick arches, empirical formulas have been derived from elastic theory that place design restrictions on arch dimensions to avoid development of tensile stresses. McDowell2 cites three main conditions for stability in sprung brick arches: 1) the thrust line of the arch should be maintained in the middle third of the thickness to avoid tensile stresses and resulting open joints in inner and outer curves of the arch; 2) the angle between the line of thrust at any joint and a line perpendicular to the joint must not exceed the angle of repose between brick; and 3) the maximum pressure at any point must not exceed the strength of the arch materials at furnace operating temperatures. The first and third conditions are particularly important in designing sprung-arch basic roofs because of the comparatively low hot strength of basic brick. According to McDowell&apos;s equation, if the thrust line is maintained within the middle third of the arch thickness, the unit pressure is obtained as follows: where p = unit pressure in psi, F, = resultant thrust normal to skewback in pounds per foot, t = arch thickness in inches, and z = distance in inches of thrust line from arch axis. When the resultant thrust normal to the skewback acts along the arch axis, z equals zero and unit pressure is simply the thrust divided by the cross-sectional area. If the thrust line moves to the limits of the middle third of the arch thickness, beyond which tensile forces would develop, z then equals one-sixth of the arch thickness and the unit pressure is double that when the thrust line is acting

Jan 1, 1968

By L. R. Raymond, J. L. Hudson

This paper proposes a comparatively short-term (8 to 10 hours) well test for detecting and characterizing well-bore damage and for measuring mean formation permeability. The proposed test is made by injecting fluid at constant pressure, recording injection rate as a function of injection time. After one to four hours of injection, the well is shut in and fall-off of bottom-hole pressure is obtained as a function of shut-in time. Formation permeability is estimated by an iterative technique. First, a value of formation permeability is assumed. Then, a plot of the recorded injection rate as a function of dimensionless time is made, using the assumed pertneability value. From the slope of the injection-rate curve. a new value of formation permeability is calculated. If the new value agrees with the original assumed value, the assumption was the correct formation permeability. If the values do not agree, the process is repeated using the new permeability value in the calculation. Convergence is rapid, and a reliable permeability value results. Pressure fall-off data are used to check the result. Graphs of pressure and injection rate us functions of time given in the paper show that changes in permeability of the formation in the neighborhood of the wellbore are disclosed by this technique. Thus, the short-term test can he used to detect formation damage. Also, a rough measure of the radial extent of damage can be inferred, which is helpful in designing stimulation treatments. The mathematical model used for this work was a single-zone, horizontal reservoir with a damaged zone in which permeability decreased continuously as radial distance to the wellbore decreased. This model is more realistic than the usual two-zone, discontinuous permeability model used in published works; calculations indicate the realistic model is valid. Vertical variations in horizontal permeability were studied with this model, and results indicate that the permeability measured by the short-term test is the mean horizontal permeability for the vertical interval tested. The proposed short-term test thus should be useful in detecting and characterizing formation damage and in measuring formation permeability needed in calculating reservoir transmissibility. INTRODUCTION To plan the most efficient production or injection schedule for a well and to design or evaluate the optimal stimu- lation treatment, it is necessary to know the properties of the reservoir adjacent to the well, particularly the reservoir transmissibility and characteristics of a damaged zone, if one exists. Several techniques for determining reservoir transmissi-bility from well tests have been presented in the literature. 1,2,3,4 All these techniques rely on conducting constant-rate well tests that often are difficult to execute. A constant-pressure well test is generally easier to carry Out. and this paper contains the first available method for the analysis of constant-pressure well tests. Determination of wellbore damage from transient well tests has been the subject of several papers."" From these studies it is apparent that information necessary for determination of the characteristics of a damaged zone is available shortly after the transient well test is initiated. Consequently, it may not be necessary to carry out an extensive well test (for example, a pressure build-up test) if the primary purpose of the test is to detect the existence of wellbore damage. All previous studies of well testing to determine wellbore damage have been based on the two-zone perrneability model. In this model the damaged zone has a permeability k,, extending to a radius r,,, and the formation permeability k obtains from r, to the drainage radius r,.. Consequently, there is a discontinuity in permeability at r = r,,. This discontinuity can be eliminated by assuming a continuous variation in permeability through the damaged zone. The effect of this assumption on transient well tests is discussed in following sections of this paper. In addition, all formations have within them vertical permeability variations associated with lithology changes throughout the zone of interest. This paper also considers the effect of these variations on transient well tests. ANALYSIS OF CONSTANT-PRESSURE WELL TESTS The mathematical analysis associated with the injection of fluid at constant wellbore pressure into a single-zone, horizontal reservoir completely filled with a fluid of small and constant compressibility and constant viscosity is given in Appendix A. In this analysis it is assumed that the well is located at the center of an undamaged, circular drainage area. From this analysis, the formation permeability can be obtained as follows. 1, Estimate a value for the formation permeability k. 2. Prepare a plot of injection rate q vs

Jan 1, 1967

By W. C. Elmore

THE magnetic powder method, long used. for roughly mapping mag-netic fields, has recently been refined 1,2 for investigating the microscopic variations in the surface magnetization of ferromagnetic crystals. Bitter2 first discovered regular powder patterns connected with the crystal structure of such specimens. Several other investigators3 have used Bitter&apos;s original technique, with slight modifications, to study the varia-tion of the patterns with variations in the magnetizing field applied parallel to the surface, and their dependence upon the state of strain, of polish and of crystal cut. All of the explanations of these patterns on metallic ferromagnetics have been couched in general terms. In a preliminary report we have described an improvement in the powder technique which led us to the discovery of a new effect throwing con-siderable light on the magnetic secondary structure of alpha iron4 and of nickels single crystals. We now report additional evidence confirming the existence and stability of a magnetic block secondary structure.

Jan 1, 1936

By J. E. JR. Johnson

AT the Cleveland meeting of the Institute in October, 1912, I had the honor to present a paper outlining the conditions surrounding the charcoal iron industry, and giving some of the results of an investigation started about three years ago for the purpose of determining the reason for the poor reputation of the Lake Superior charcoal irons as compared with the Southern and Eastern irons. In that paper I explained the effect of high carbon on quality, and tried to make clear that that paper was a preliminary one, as we felt convinced that we should eventually discover other factors affecting quality. The progress of the investigation has brought out facts that seem to us of the utmost importance practically and theoretically, and the purpose of the present paper is to present these facts with the proofs which seem to us to establish them. The closing year of the nineteenth century saw the publication of the first definite and connected statement of the relationship between the cast irons and the steels.&apos; The metallurgical world was ready to accept the fundamental unity of these two series, acceptance being greatly hastened by Professor Howe&apos;s classic paper, The Constitution of Cast Iron, presented at the Richmond meeting of the Institute, February, 1901.

Jan 1, 1914

By Charles H. Fulton

Experimental work on the process was begun on a laboratory scale at Cleveland, Ohio, in 1914, and transferred to East St. Louis, Ill. in 1916, where a commercial sized furnace was in technical operation until January, 1918. The essential steps of the process are as follows: Oxidized zinc ore or roasted zinc concentrate is mixed with crushed coke and coal-tar pitch and formed into briquets 9.25 in. (23.5 cm.) in diameter and 21 in. (53 cm.) long in a manner similar to that used in the manufacture of graphite or carbon electrodes, except that much less care and time are required. The composition varies with the nature of the ore; in one case, the composition was 100 parts ore, 70 parts coke, and 18 to 20 parts pitch. These briquets maintain their form and volume during and after the distillation of the zinc. This object is gained by using coke as the matrix and coal-tar pitch as the binder; this pitch becomes coke on heating and unites the ore particle and the original coke particle into a continuous mass. The briquet is an electrical conductor but only to such a degree that it can be used as a resistor. The size of the ore, as in the present practice of zinc metallurgy, ranges from fine material, such as flotation concentrate, to coarse table and fine jig concentrate. The process is not restricted to any particular kind of ore, but is applicable to pure high-grade ores, ores high in iron, and complex zinc-lead ores, since the residue from the distillation IS held immovably in place within the briquet. In the case of complex zinc-lead ores, the distillation is conducted with a carefully regulated temperature so that a high percentage of lead is retained in the distilled briquet, which may then be smelted for its lead content. In present zinc smelting practice, the reduction fuel is from 40 to 50 per cent. of the weight of the ore. In the briquet, it is from 60 to 85 per cent. of the ore; but unless the ore is exceptionally high in residue, the distilled briquet may be used over again as coke, or as a high ash coke for fuel purposes in power production. Baked briquets are hard and tough and may be handled roughly

Jan 1, 1921

By R. L. Loofbourow, Roger V. Pierce

THE degree to which our mineral requirements are being met by mining leaner, more complex or more remote deposits is indicated by developments during 1953. Heavy capital investment, skilled technical advice, planning, and able execution are requirements for the typical venture. Producers, faced with rising costs and with softer prices, are seeking improved mining and recovery. Developments in production of iron ore are typical of the course being followed in metal and nonmetal mining. Iron ore development in the U. S. is concentrated on the spectacular work with Lake Superior taconite, while in Canada new production is expected from Labrador and output from Steep Rock, Algoma, and Newfoundland is being increased. Shipment of iron will soon be made from Venezuela.

Jan 2, 1954

By L. W. Bahney

(Cleveland Meeting, October, 1912.) THE photograph, Fig. 1, shows the apparatus a little less than half size, consisting of a filtering-flask fitted with rubber stopper, through which passes a bent glass tube, and an extraction-thimble fitted with rubber stopper through which passes a glass tube of 0.2-5-inch bore. Both tubes are connected by a short piece of rubber tubing. A section of a thimble is shown in the photograph; the tube extends to within in. of the tapered end. The object of using the thimble is to remove the acid from the beaker after all the copper has been precipitated. Time is saved, the copper is not exposed to the acid alone, and there are none of the losses attending ordinary filtration. I have accomplished these results by means of a piece of perforated platinum fastened in the end of a 0.25-in. bore glass tube and a filter-mat of asbestos, but after my supply of proper length fiber became exhausted I could not replenish it even after purchasing 14 lots from four different dealers. The above apparatus may be used to remove at least seven-eighths of a supernatant liquid from a settled precipitate without disturbing the latter. The application of the thimble is best shown by partly out-lining the assay for copper, as follows: Dilute the acid solution of copper and other sulphates to 150 cc. in a 200-cc. Jena beaker, place on a hot plate, add 2 drops of concentrated HC1, then place a strip of aluminum in the beaker (this may be bent or straight, as desired). Connect the apparatus, as shown in Fig. 1, with a filter-pump having a, strong suction. When the copper is precipitated, remove the beaker from tine hot plate and insert the extraction-thimble alongside the strip of aluminum. The acid solution will be drawn through the porous tube. Wish the upper end of the aluminum strip with a jet of hot water, wash down the sides of

Nov 1, 1912

By D. M. Metcalf

MOST PEOPLE think of peat as an inferior substitute for coal as a fuel, and will be surprised to learn that it is extensively mined in this country for use as fertilizer rather than as a fuel. Some years ago the Florida Humus Co. began producing it at Zellwood, Orange County, Fla., in a small way for local use. When, however, the company secured an Institute member, M. H. Cuise, to apply his wide experience in mining to the problems here it was found possible to decrease production costs 70 per cent and increase output tenfold. The obvious way in which to decrease costs was to replace shovel-and- horse methods with machinery, much of which, in order to keep down-invested capital, was improvised by remodeling second-hand equipment, changing the design where necessary to meet the special conditions involved.

Jan 1, 1932

By AIME AIME

DESPITE the meetings and discussions on over- production the situation still continues to grow worse instead of better. The demand for oil has dropped to 2,700,000 bbl. per day. On the other hand domestic production has risen to 2,700,000 bbl. with prospects of further increases, and if imports and natural gas-gasoline be added to this the current supply is about 3,100,000 bbl. per day. Though during the summer and early fall the demand may exceed this figure for a few months the prospects are that &apos;the average demand during 1929 will be at least 200,000 bbl. per day less than the present current supply, meaning additions to stocks over the year of about 75,000,000 bbl.

Jan 1, 1929

By AIME AIME

THE Employment Bureau of the F. A: E. S., conducted under- the direct supervision of the secretaries of the four Founder Societies, has wanted to extend its activities and usefulness but it is operating right up to the limit of its budget; consequently, anything which requires the expenditure of more funds cannot be -undertaken, for the present. A great deal of time has been spent in recording, classifying, and interviewing the men listed, but owing to the business depression, only a comparatively small number of men have been placed&apos; luring the last few months. There are men in New York from all over the country. What the Bureau needs is more positions available. With this in view, a number of high-grade engineers, themselves in need of employment, volunteered their services for a publicity campaign in the City of New York. A definite mode of procedure was evolved, and the success of the movement has been considerable, so much so that it has been thought well to call it to the attention, of members elsewhere, so that similar committees &apos; and campaigns might be organized in other cities. Following is a chronological arrangement of the methods used.

Jan 1, 1921

By AIME AIME

AN entirely new type of classifier is being put on the market by The Dorr Co., following three years of development and the experimental use of thirty machines of the improvement design in various parts of the world. It is known as the Multizone classifier. Compared with the older type the lower or overflow end has been decked over and is surmounted by one or more circular overflow columns. Feed is introduced near the middle of the machine and passes downward and under a vertical baffle, then along the underside of the deck to the base of the overflow columns. Under the baffle there is a restricted turbulent zone of high pulp velocity which holds the fine and critical size particles in suspension, preventing

Jan 1, 1937

By Ralph D. Parker

A STRIKING testimonial to the value of safety was contained in an ad- dress given in May, 1936, by A. R. Young, vice-president of the United States Steel Corp.: In the period from 1906 to 1935 we have spent $24,860,540 on safety work. By comparing the cost of "prevented" accidents by the cost of settling similar accidents, we found that we had made a saving of $117,224,238. Even if those figures are 50 per cent wrong, at least we got back every dollar we paid for safety and another with it. I don&apos;t think anyone has to blush before his board of directors for an investment of that kind.

Jan 1, 1937

By Carrol A. Quam

DURING the first years of operation of the titanium and iron mine of the National Lead Co. at Tahawus, New York, efforts to increase production were hampered by the increased load put on the facilities for sharpening churn-drill bits. The ore and rock are extremely hard and abrasive and it was necessary to sharpen and harden a large number of bits per day to keep the churn drills supplied. Efforts to increase the capacity of the bit shop by a two-shift operation were not wholly successful in that it was hard to train men to do a satisfactory job of sharpening and tempering the bits. The number of bits that were improperly tempered increased, thus boosting the daily requirements for bits at the drills and increasing the load on the bit-sharpening facilities.

Jan 1, 1949

By L. W. Bahney

FREQUENTLY in using a thermo-electric pyrometer for measuring the temperature of a furnace, a hole is drilled at the back or side of the furnace, through which is introduced the tube containing the thermo-couple. At times the couple is left almost where it drops, for the reason that it soon becomes too hot to be handled easily, and the space at the back or side of the furnace may be so small and uncomfortably hot that an easy and accurate adjustment is nearly impossible. In order to overcome this clumsy and unscientific method of using the thermo-electric pyrometer, I designed an adjustable stand, to hold the clay or quartz tube unclosing the platinum and plati-num-rhodium leads that constitute the couple of the Le Chatelier thermo-electric pyrometer. This stand also allows an easy and rapid adjustment of position to varying heights and angles, as may be desired for special reading. This stand is illustrated in Fig. 1. The couple in the tube might be of better service if the tube were held a little higher above the charge in a roasting-dish, changing the height and angle if desired. The stand, made of 1.5-in, water-pipe and mounted on casters, is heavy enough so it cannot be tipped over easily. It is adjusted to any position, and has a universal clamp which holds the clay or quartz protecting-tube. To avoid disturbing the wires of the couple at the cold junction each time the tube is moved, the cooling-bottle sets in a wire basket so placed that it moves forward or back with the couple. To overcome the necessity of leveling and adjusting a galvanometer at each furnace, a switch-board is used to connect

Jan 1, 1910

By Orson Cutler Shepard

RECENT research work in the flotation concentration of minerals has been concerned mainly with flotation reagents and the mechanism by which collecting reagents are held to the surface of certain mineral particles. The fundamental question of why air bubbles cling to properly prepared mineral surfaces is usually dismissed with the statement that the surface is air-avid or water-repellent. In my article in MINING AND METALLURGY for June, 1932, I showed theoretically that surface tension relationships govern bubble attachment in Rotation. This explanation has not been accepted by many; probably be¬cause the difficulty of measuring solid-solution surface tensions prevented obtaining experimental evidence. If the surface tensions involved in the system [solution, mineral, air bubble] are responsible for attachment of the air bubble to the mineral, any change in the surface tensions should cause a corresponding change in the attachment of the air bubble. An example in which the mineral-solution surface tension could be varied was found with mercury. When mercury is in contact with solutions of certain electrolytes the surface tension at the contact of mercury and solution can be altered by electrical polarization of the mercury. The surface tension rises to a maximum as the mercury is given an increasing negative potential and then decreases with further increase in potential. The theoretical relation between the surface tensions and the attachment of an air bubble is given by the following equation:

Jan 1, 1936

By H. M. Roche

MAGNETITE mining and milling in the Eastern States in 1939 showed considerable improvement over 1938. For the first eight months of the year production of magnetite proceeded at a normal rate but operations were stepped up in the last four months owing to increased domestic demand. In New York, the Republic Steel Corp. operated the Witherbee-Sherman mines at Mineville throughout the year. Chateaugay Ore and Iron Co. operated their low-phosphorus mine at Lyon Mountain for the first seven months, but on Aug. 1, Republic Steel took over this mine -and have since operated it. In Pennsylvania, the Bethlehem Steel Co, operated the Cornwall mine continuously. In New Jersey, Mt. Hops and Scrub Oak were in operation all year. The Washington mine went into production on Nov. 1 and the Richard mine on Dec. 1.

Jan 1, 1940

By R. W. Raymond

PROF. HENRY Louis, of Armstrong College, Newcastle-on-Tyne, England, a distinguished member of this Institute and other technical societies, has recently sent to the Institution of Mining Engineers, and to the Institution of Mining and Metallurgy, in Great Britain, a communication, the substance of which is as follows Prof. Louis calls attention to the absence of any recognized English term for the definite description of a frequent phenomenon-namely, the oblique position of an ore-body in the plane in which it. lies. In this connection, Prof. Louis says that in America the term " pitch " has been occasionally applied to this relation, and proposes that, in the literature of ore-deposits, it shall be hereafter restricted to this particular meaning, the angle of the pitch, like that of the dip, being always measured from the horizontal, and the dip being always taken at right angles to the strike, while the pitch is taken on the plane of the dip, in the direction of the strike. Thus, for example, in a vein or bed striking N-S., and dipping, say, 45° E., there might be an ore-body, the axis of which pitched northward, at an angle of 45° below the horizontal line, as measured on the plane of the inclosing vein or bed. If the term " pitch " had this universally recognized meaning, the situation could be simply and perfectly expressed by its use, in connection with the general data of strike and clip. As Prof. Louis says ?This suggestion has a certain practical value, and is not merely academic. Every mining engineer of practical experience in such types of ore-deposit will have met with cases, in which a vertical shaft has been sunk with the object of cutting the deposit, but has missed it, because the dip alone has been taken into account, while the pitch has been overlooked." He adds the acute observation that such an oversight is much likelier to occur with regard to a condition not definitely desig-

Mar 1, 1908