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By Paul M. Tyler

The technology of clay and the manufacture of ceramic products therefrom, and also the clay resources of most of the individual States, are already covered by a voluminous literature. The present resume touches these matters only briefly; its purpose is essentially to bring together in small compass certain of the elementary factors affecting the potential commercial value of a clay deposit. In its preparation the author made extensive use of the annual chapters on Clay in Mineral Resources of the United States and in the two annual issues of the Minerals. Yearbook that succeeded them. For careful review and constructive criticism of the manuscript, the author is indebted to Hewitt Wilson. GENERAL DESCRIPTION The term ?clay? includes a great variety of substances that may differ widely in chemical mineralogical and physical properties. No two clays are exactly alike. All of them however, have the prominent characteristic of becoming more or less plastic when wet. Nearly all of the useful clays can be molded into articles, will hold their shape while being dried, and can be converted into a hard, rocklike substance by heat. Clay may, and in fact usually does, consist of a number of minerals among the commonest of which are kaolinite, quartz, feldspar, iron oxides, mica, bauxite, calcite, and manganese oxides. Organic matter is often present. Pure kaolinite, which has the formula A1203. 2 SiO2. 2H2O, is ordinarily, considered to be the parent "clay substance," butt most clays contain other hydrated mixtures of alumina and silica (aluminosilicic acids) along with indefinite amounts of sand and other nonessential minerals3/ Even, this so-called inert matter affects the plasticity, drying shrinkage, ease of drying, and final density, and at high temperatures may react chemically with the clay substance.

Jan 1, 1929

By S. S. PRENZ

Discussion held at the sessions of the Canal Zone meeting, November, 1910. [SECRETARY'S NOTE.-As a result of this discussion, an expression of opinion covering all points of unanimous agreement was adopted and signed by members of the Institute party as individuals. This statement, which was printed in the Bulletin of December, 1910, is reprinted below, as an introduction to ,the detailed report of the discussion. It should be clearly understood that it does not constitute an official declaration by the Institute, the rules of which forbid any such action. At the New Haven meeting of February, 1909, a free discussion of the plan of the canal took place, in which the critics of the present scheme had full opportunity to state their views. That discussion was continued at considerable length in the newspapers ; but the Institute was never committed to either side. In this latter instance, the situation is precisely similar. Certain members and guests of the Institute, having had the advantage of later developments and of personal inspection, have expressed the conclusions at which they have arrived on their own responsibility ; and these conclusions are published by the Institute, subject to further discussion, like any other part of its proceedings. The general statement referred to contained a promise that the full discussion, of which it was a result, would be subsequently printed ; and this promise is fulfilled, so far as practicable, in the subjoined report, concerning which I beg to offer the following explanations: 1. It is made up of the remarks of the members of our party, as subsequently written out and mailed to the Secretary. 2. In editing these contributions, I have condensed the material considerably by cutting out much repetition of opinions and phrases ; and in such excision, I, frankly confess, the authors whose communications were delayed, have been the sufferers. Nevertheless, there is a good deal of repetition left, as there must be, when so many persons had talked so much, and come to agreement upon so many points. 3. It has been found impossible to preserve in this report the actual order of the free and informal oral discussion represented. Consequently the several contributions have been arranged in alphabetical order under the names of their authors. References to "preceding speakers," etc., must therefore be construed as referring to other speakers, preceding or following.-R. W. R.] S. S. PRINZ AUGUST WILHELM, AT SEA, November 14, 1910. We, the undersigned, members and guests of the American Institute of Mining Engineers, after a visit to the Isthmus of Panama, and inspection of the work of the United States Isthmian Canal Commission, and after full discussion of our individual impressions, find ourselves in unanimous agreement as to the following conclusions:

Jan 1, 1911

By R. N. Powell

The Pipeline ore body was discovered in March 1991. The construction of the new mine and mill did not start until early March of 1996. Upon completion of permitting and corporate project approval, the 289 million USD project was “fast tracked”. The commissioning began 11 months after start of construction and the project ended 40 million USD under the budget figure. The objective of this paper is to review and highlight the Pipeline Project history from discovery, design, lawsuits, permitting, and re-design through to current - 1998operating practices. Particular emphasis will review the process design, design mistakes, and design successes. The paper will review project history, feasibility, design concepts, operator training, construction, financial and the current operation. Additional discussion will review what design features worked and which did not work within the process plant.

Jan 1, 1999

By I M. Turnbull

QMAP (the Quarter Million Mapping Programme, 1:250 000 scale) is a geological mapping programme which will build a digital geological database of the whole country and publish maps and books to document it. The programme was established in 1993, following a recommendation by a review panel appointed by the Ministry of Research, Science & Technology, and is funded by the government, from the Public Good Science Fund. The relevance and fundamental value of QMAP lies in the greatly improved geological knowledge it will provide for researchers and other end-users of geological information.   QMAP research involves assessment of previous work, field and laboratory investigations in key areas, and data storage, manipulation and publication using Geographic Information Systems (GIS) computer technology. The QMAP digital database of New Zealand geology will be completed by 2006, as will the series of 21 full colour printed geological maps and accompanying explanatory texts. Two are already completed and published (Kaitaia and Dunedin), and six other projects are well advanced.   QMAP information will also be available in digital form. Next year we hope to expand the scope of the programme to cover the reconciling and linking of many other earth science databases to QMAP, because we believe this will create a powerful research tool. The intention is to develop internet access to the databases, to make the information publicly available.

Jan 1, 1997

MARCH 15-Industry is rapidly snapping back from another coal crisis, other business news is in general favorable and the outlook through the Spring is by most observers considered quite promising. Most industries report comfortable backlogs of unfilled orders, department store sales in recent weeks have equalled in dollars those of the corresponding period last year, retail sales of automobiles show again over the same period a year ago, and new orders for machine tools are at the highest figures since August 1946. Orders for railway freight cars have shown a very encouraging pickup, with a total of 9385 cars in January and the N. Y. Central alone ordering 4500 in February. Construction continues very active. In January new housing starts totaled 80,000 against 50,000 a year ago and the daily average contract awards, according to the Dodge reports, were 57 pct larger. In the first 22 days of February the increase in awards was 27 pct. Lumber orders since Jan. 1 have run 22 pct above last year. All of these favorable factors bolster the opinion that the upturn in industrial output and employment which began last summer has not yet spent itself and that the setback caused by the strikes will be made up when people get back to work. Only in a few lines are there indications that primary production may be outrunning the consumption of finished goods, although inventory build-up would seem to be rather modest as the National Association of Purchasing Agents reported in February that 78 pct of its members were buying for 60 days or less. Industrial prices as a whole show no significant trend despite the continued alarm over both the immediate and the long-term possibility of inflation caused primarily by the government's increasing expenditure and its inability to balance the budget. A recent advance of 1.9 pct in primary market prices is viewed by some people as the surface symptom of renewed inflation, but even so it is more than two years since the alltime high was reached by the daily index of sensitive commodities in November 1947. Over two years have passed since prices received by farmers hit their peak and about a year and a half since all wholesale prices and the consumer price index touched their highest points in August 1948. The decline in the wholesale price index has been almost continuous, interrupted only twice by slight advances in the monthly figures from February to March 1949, and, later in the year, from August to September. Of course, this continued decline in the last half of 1949 largely reflects a downward movement in farm and food prices. Wholesale prices for commodities other than farm and food leveled out after June and now stand only slightly under the June level. Farm products are down by 22 pct from January and by 18.6 pct from August 1948. Food prices are down only slightly less. Consequently, the farm price support program is in serious trouble and has imposed a heavy financial burden on the Treasury. In those commodities other than farm products only building materials, chemicals and textiles have come down as much as the average, while housefurnishings and metals and their products have fallen hardly at all. Glancing away from the domestic front, the results of the British general election indicated a highly inconvenient situation, that public opinion there is so exactly deadlocked as to divest the victors of much ability to make forceful decisions or create significant policy. It is generally considered that another election in the near future would give substantially the same result. The British people are equally divided and the politicians are not likely to precipitate another appeal to the country until there is manifest reason to believe that external and internal circumstances have changed sufficiently to permit one party or the other to obtain a decisive verdict. Because of the lack of a clear mandate steel nationalization will likely lag in Britain. In the meantime there is considerable discussion going on as to whether the European steel industries as a whole are at a disadvantage in world competition with the American industry. An article in the "Statistical Bulletin" for January of the British Iron and Steel Federation takes issue on this point with the authors of the Geneva report, observing that they wrote before devaluation, and this particular conclusion "has been overtaken by events." The "Bulletin" also contends that the statement was in any case incorrect so far as Britain was concerned, and that it was based on scanty and insufficient evidence. To support the rebuttal a detailed and extensive comparison is made of the home prices of certain steel products in Britain and in other countries of the world. The accompanying table gives a selection of the prices published. It sets out the changed position since devaluation and since the recent increases in American steel prices. These are home market prices; no doubt in competitive export business some of the price levels could be brought closer together at need.

Jan 4, 1950

By R. F. Miller, R. F. Campbell

Sixteen steels containing different combinations of chromium and molybdenum, in amounts up to 5 per cent of each element, were examined for microstructure and hardness after air cooling and after furnace cooling from suitable austenitizing temper- atures. Diagrams summarizing the structnres and hadness resulting from these two cooling rates are presented (Figs. 3, 4, 7).t Data were also obtained on the influence of these two elements, individually and in combination, on the depth of decarburiza-tion observed after furnace cooling (Fig. 8). Composition of Material The chemical composition of the steels investigated is given in Table I. The plain carbon steel was made in a 2 5-ton Heroult electric-are furnace, while the alloy steels were made in a 4.5-ton Ajax-Northrup elec- tric induction furnace. The cast ingots were hot-rolled to 1.75-in. bars. Air-cooled Series The I.75-in. bars were forged to flat plates, 0.25 in. thick, from which specimens 0.5 in. wide by 2 in. long were cut. The specimens were pretreated to improve their homogeneity by heating to 1830°F. (I000°C.) for 20 min. and oil-quenching. They were then reheated to 1740°F. (950°C.) for one hour and air-cooled, after

Jan 1, 1942

By J. A. M. Cano

Introduction Since the beginning of operations at the pellet plant at Ponta Ubu ES, Samarco Mineração SA has produced pellets for direct reduction and blast furnace processes. Of the total amount of pellets produced from 1977 through 1993, 55 % are used in the blast furnace, about 45 Mt (49.6 million st). The principal components of pellet gangue are calcium oxide, magnesium oxide, silica and alumina. They should be added in adequate quantities to guarantee the mechanical resistance of the fired pellets under blast furnace conditions. Over the years, the pellets produced by Samarco had a silica content between 2.5% and 2.8% and varying binary basicity preferably between 0.8 and 0.85. On the other hand, the increasing amount of industrial waste in siderurgical plants caused by the increase of steel production has caused some countries to put into practice methods to reduce the volume of slag produced in the blast furnace. This paper's goal is to find an alternative for decreasing the amount of slag produced in the blast furnace. It is possible to decrease pellet gangue by decreasing the silica content to about 2%, leaving the metallurgical properties and quality of pellets unaltered. For this work, Samarco pellets were used with Si02 between 2.5% and 2.8%, pellets with high silica and pellets with Si02 between 2.0% and 2.3% low silica. Both were partially fluxed by the range of varying basicity CaO/SiO2 from 0.8 to 0.95 during production. Experimental tests on pilot scale Thhis work began in January 1986 in the pilot plant (pot grate, Fig. 1) at Samarco. Its goal was to obtain preliminary data that would indicate the bybility of the project. It also formed a solid base to extend the studies in tests on an industrial scale of production for blast-furnace pellets. The pot grate is a test furnace composed of a gas burner, a combustion chamber and a grate, connected by hot air ducts. The burner is fed by a mixture of LPG and air. It reaches high temperatures through oxygen injection. The combustion chamber heats the air that comes from the turbocompressor. This hot air flows through the ducts to the grate on which the pellet samples are fired. During updraft drying, downdraft drying, preheating, firing and afterfiring, the upward and downward direction of the air flow can be controlled by valves driven by pneumatic cylinders. The pot grate indurator was fully automated in August 1989. Positive and negative pressures measurements resulting from gas passing through the pellet layer, as well as temperature readings, are recorded in graphs in relation to time for all tests. The tests depend on the various steps carried out in sequence that can influence the results of the tests. Therefore, some criteria were adopted to restrict the number of variables in the process. This was done to facilitate the results of the analysis. The pellets were composed of concentrate, bentonite, hydrated calcitic lime and metallurgical coal, all regularly used in the pellet plant. The material balance of the pellets mix was determined from the chemical analysis of the components. Table 1 shows the chemical characteristics of the concentrate and the additives used in the pilot plant and industrial tests. The basicity has a marked influence on the metallurgical properties of the pellets produced by Samarco with a silica content between 2.5% and 2.8%. However, for pellets with low silica (about 2%), it was necessary to study the variation in the parameters of quality in a wide range of basicities to deliniate with precision a scope of work. A large variety of low-silica blast-furnace pellets were produced at the pilot plant with binary basicity varying between 0.8 and 0.95. After chemical analysis, those pellets were separated into five groups of different binary basicity (0.8, 0.84, 0.87, 0.90 and 0.95). Each was then split, one part for metallurgical tests in the laboratory at Samarco and another to be evaluated in a laboratory for metallurgical tests in Germany. It was agreed that the tests to evaluate the quality of the pellets in the two [ ]

Jan 1, 1996

By R. F. Campbell, R. F. Miller

Sixteen steels containing different combinations of chromium and molybdenum, in amounts up to 5 per cent of each element, were examined for microstructure and hardness after air cooling and after furnace cooling from suitable austenitizing temper- atures. Diagrams summarizing the structnres and hadness resulting from these two cooling rates are presented (Figs. 3, 4, 7).t Data were also obtained on the influence of these two elements, individually and in combination, on the depth of decarburiza-tion observed after furnace cooling (Fig. 8). Composition of Material The chemical composition of the steels investigated is given in Table I. The plain carbon steel was made in a 2 5-ton Heroult electric-are furnace, while the alloy steels were made in a 4.5-ton Ajax-Northrup elec- tric induction furnace. The cast ingots were hot-rolled to 1.75-in. bars. Air-cooled Series The I.75-in. bars were forged to flat plates, 0.25 in. thick, from which specimens 0.5 in. wide by 2 in. long were cut. The specimens were pretreated to improve their homogeneity by heating to 1830°F. (I000°C.) for 20 min. and oil-quenching. They were then reheated to 1740°F. (950°C.) for one hour and air-cooled, after

Jan 1, 1942

By Aylmore M. G

Samples have been taken from a two-stage industrial gold roaster treating a pyrite/pyrthotite/arsenopyrite concentrate, in order to describe the mineral- ogy, composition and surface area of the calcines. Sulfides oxidised to produce a porous magnetite in the first stage and a porous hematite in the second, pyrite predominantly roasted via a pyrrhotite intermediate. Sulfur was eliminated in both the first and second stages whereas arsenic was eliminated in the first but retained in the second, partly as rims on hematite particles. The finer sized particles from the cyclones and electrostatic precipitator, whilst having the greatest surface area, were the most refractory with respect to gold solubilization, probably as a result of incomplete decomposition (through short-circuiting) in the first stage, and through a combination of factors such as overheating and entrapment of sub-micro- scopic gold in the second stage.

Jan 1, 1991

By B. V. Driga

The paper presents the evaluation method of the thermal power potential of the salt lakes developed in collapsed salt mines in Romania. It is well-known that the hydro-chemical stratification of these lakes favors warmer internal layers. The degree of heat varies during the year, but, taking into account the large number of genetic lakes of this type, it can be used as a local utilizable power source. The authors analyze the correlations between the physico-chemical parameters of the water and the degree of heat stored as a function of the morphological parameters of the lakes, as well as the technical parameters for capitalizing on this power.

Jan 1, 2008

By James S. Graham

Marine design and construction methods are presented on the caisson foundations for the tower piers at the Brooklyn, Ben Franklin, Delaware Memorial 1st, Tappan Zee, Walt Whitman, Throgs Neck, Verrazano Narrows, Delaware Memorial 2nd, and Newport Bridges. All of the bridges are founded on caissons, bearing on bedrock, soil, or piling. Caissons at the Tappan Zee Bridge are partially supported by piling and partially by buoyant forces. General subsurface conditions for each are provided. The purpose of this paper is inform engineers how bridge foundations using caissons were built over major waterways in the Northeastern USA in the past, anticipating a surge of new bridge construction in the near future.

Jan 1, 2013

By Yi Luo

Bolting the mine roof is one of the noisiest underground mining operations. The main contribution to the high noise is the drilling of the roof bolt holes, especially in hard rock. A previous research shows that the specific energy consumed in drilling the bolt holes is inversely proportional to the bite depth (i.e., penetration per drill revolution). Less specific energy at a reasonably high bite depth means less energy is wasted in the drilling process to produce heat, bit wear and noise. Therefore, control of drilling operation to achieve a higher bite depth can provide an opportunity to reduce drilling noise from its sources as a proactive noise control approach. In order to explore the feasibility and to develop the proactive technology for reducing drilling noise, drilling tests have been conducted in laboratory settings. The preliminary results show significant reduction in noise dose can be achieved by drilling in medium hard rock at a reasonably high bite depth. This paper presents the findings from the laboratory experimental studies conducted so far.

Jan 1, 2013

Robertson Diasol have developed a spectral gamma-gamma tool fully able to withstand borehole conditions. Spectral data is digitally recorded across 256 channels depending on energy levels of the photoelectric effect. Data processing is being developed with the objective of calibrating channel amplitudes to mineral type which will lead to a direct log of selected mineral grade as a continuous trace with depth.

Jan 1, 1990

By D. B. Dow

This report on methods employed for dehydrating oil-field emulsions, is the second of a series prepared as a result of a study of oil-field emulsions recently completed by the writer. The first paper2 dealt with the factors responsible for the formation of emulsions. A third paper will discuss the physical chemistry involved in the formation and resolution of such emulsions. In the early development of the oil fields of Pennsylvania, no emulsion troubles of any consequence were encountered, nor to any serious extent in the oil fields of other Eastern States: However, with the development of fields west of the Mississippi in Oklahoma, Kansas, Texas and California, where heavier oils of different characteristics were found, the problem of dealing with cut oil soon became of great importance.

Jan 1, 1925

By Arthur F. Taggart

PROGRESS in a technical art is of several kinds. It springs .from many diverse sources. It comprises invention, mechanical improvement, operating advance, analytical study, education. Invention is, by definition, a relatively great, essentially individual step, taken quickly. Operating advance is the slow, cumulated march of practice; in contrast, it moves at the pace of the tortoise, but over, the years its effects rival and, in some cases, surpass those of invention. Mechanical improvement- is a usual concomitant of the reduction of invention. to operating practice; thereafter it is a primary tool of operating advance. Analytical study is the process of mental digestion of the fruits of invention and practice. Its purpose is to render these into a form assimilable by the art as a whole, and by the perennial crop of would be practitioners. Education, disseminating the results of such study, consolidates and maintains the positions gained. Thus, slowly at first, but continuously accelerating, the tide of progress grows- to flood. Such growth, in mathematical parlance, is expressible in the general form y = mxn, where x is time, n is some positive number greater than one, m is another positive number, and y is the state of the action at instant x. When n is 2, the readers will recognize the graph of the equation as one branch of the familiar square parabola, whose property it is to become parallel to the y-axis; i.e., to move at an infinite rate, in that never-never

Jan 1, 1947

By P. de Vitry, Oliver Bowles

The conventional wire saw, introduced in the slate district of Pennsylvania by the Bureau of Mines in 1927, and used thereafter with remarkable success, consists of a three-strand steel cable having a diameter of 93/16 or 54 in. The equipment, methods used, and accomplishments have been described in previous reports.'-I Similar wire saws have been used extensively in Europe, in quarries and in shaping blocks and slabs. During the period 1932-1937, competition in European marble quarries was keen, prices were declining, and orders were not abundant. When orders were received, there was generally an urgent call for speedy delivery. Because of the diversification of demands, it was impossible to maintain in stock marbles of the color, size, and thickness called for, therefore the material generally had to be fabricated after the order was received. The wire saw enabled stone mills to fill such orders promptly. With skillful handling, 7/8-in. slabs could be cut accurately and rapidly with this equipment. It was found, however, that, as the three-strand wire became worn, the cutting speed dropped rapidly and the cut became less accurate. To overcome these difficulties the junior author of this paper, after much experimentation, developed a new type of wire consisting of a single ribbon-shaped strand, twisted as shown in Fig. I. To ensure straight sawing, the twist of the ribbon is reversed from right to left and vice versa every 25 ft. The reversal of the twist is shown in Fig. 2. This is not a new feature; it has been used to advantage with the three-strand wire both in Europe and America for several years. However, some difficulties arise in splicing the three-strand reverse-twist wire, and the claim is made that cutting is less accurate as the wire becomes worn. To make an endless belt, the ends of the single-strand wire are brazed together with Pyrophyllite is a hydrous aluminum silicate (A1²Si4O10(OH)²)1 that, occurs in both the foliated and the massive forms. The foliated variety resembles talc in that it has a greasy feel, a pearly luster, perfect basal cleavage, and usually is white, although in some deposits apple green, gray, brown, russet, and nearly black specimens may be found. The massive deposits of pyrophyllite yield pearl gray to light tan aggregates, some of which are so friable that they may be crushed with the hands into a fine gritty powder. Frequently specimens of the massive variety are studded with crystals of radial structure. The mineral has a specific gravity of about 2.7 and a hardness of 1 on Mohs' scale.' The chemical composition of commercial pyrophyllite reflects the mineralogy of the deposits, which, according to Stuckey12 contain pyrophyllite and quartz, together with chloritoid, sericite, and a few other minerals of negligible importance. The latter, he says, ('are noticed in but small quantities to the extent they might occur as accessory constituents of an igneous rock or as products of regional metamorphism or weathering. . . . Quartz is abundant everywhere except in the very best grades of pyrophyllite." Analyses of specimens from several deposits are listed in Table 1, showing that the silica content varies from 57 to 73 per cent and the alumina from 22 to 33 per cent. Oxides of iron and the alkaline metals are collectively present, with one exception, to an extent of about 1 to 1.5 per cent. Sources At present, North Carolina is the only commercial source of pyrophyllite, although the mineral has been found in small quantities in many parts of the world. The North Carolina deposits are in the "Carolina Slate Belt," which traverses the center of the state in a southwesterly direction. This belt varies from 8 to 50 miles in width. Two major deposits of pyrophyllite lie along its eastern boundary, in what is known as the Deep

Jan 1, 1942

LESLIE BRADFORD GOLDEN JUBILEE ORATION "Not only a metallurgist but a scientist of the highest order" Leslie Bradford and the Australian Metallurgical Industry

Jan 1, 1987

By R. G. Treuting

Germanium single crystals strained in tension at 600°C slip on the {Ill} plane and, macroscopically at least, in the <110> direction. Deformation is in homogeneous: various localized rotations are observed, as is a banding consistent with secondary slip banding. The structure after deformation is polygonized with a domain size of about 2x1O-3 cm. In relaxation tests, an incubation period prior to flow is observed, of duration inversely related to temperature and applied stress. Under continuous loading, there is a sharp first yield point. A critical resolved shear stress therefore must be cited with respect both to temperature and to rate of loading. At 600°C, when loading proceeds at 2900 psi per min, it is 1310 psi. The yield point phenomenon is suggestive of Cottrell&apos;s solute atom atmosphere theory and five points of qualitative agreement with this theory are found. PLASTICITY of germanium at elevated temperatures has been reported by Gallagher,&apos; who ascribed it to slip on {Ill) planes and described some associated effects. Preliminary experiments with single crystals of silicon and germanium loaded as simple beams confirmed {ill) as the slip plane of both materials.V his was demonstrated by the standard technique employing traces on two surfaces of known angle on a deformed crystal of known orientation.3 These experiments did not fix the slip direction, since more than one glide system operated. Uniaxial tensile straining is preferred for this purpose in order to restrict slip to one predominant system and to provide an unequivocal determination of the orientation change with respect to the stress axis. Experimental Method Specimens were diamond-sawed from germanium crystals containing about 5x10-5 wt pct Sb prepared by the zone-leveling process described by Pfann and Olsen;4 these specimens measured about 81/2 in. long, 0.20 in. wide, and were of various thicknesses from 0.035 to 0.060 in. Prior to testing, a specimen was coated over 1 in. or more of length at each end with Apiezon wax, chemically polished (in a solution of 15 ml HF, 25 ml HNO,, 15 ml CH3COOH, and 3 to 4 drops Br2), and dewaxed in warm xylene. A brief re-etching after scribing through a complete wax coating with vernier dividers provided gage marks at 0.200 in. intervals on the polished surface. A specimen with grips soft soldered to the ends was passed through the furnace tube and the grips pinned to the tensile machine in series with a stress gage. The Schopper testing machine is best described by reference to the illustration on p. 107 of Schmid and Boas5 and is operated with the pendulum arm locked, fixing the upper head. Load is applied through the screw-driven lower head, manually or by reduced speed motor. The furnace is 21/2 in. long surrounding a 4x7/16 in. ID quartz tube and was positioned about the specimen to permit free motion. The inert or reducing atmosphere required was sufficiently provided by a flow of helium introduced at the center of the furnace tube, with the tube ends loosely plugged with asbestos paper. Surface corrosion was slight. The stress gage employs a Be-Cu strip with SR-4 units incorporated in a simple bridge network with provision for balancing and calibrating. The bridge output on loading is fed through a Leeds and North-rup dc amplifier to a Speedomax 10 mv recorder, and calibration is obtained by dead loading. Experiments of two types have been conducted. Most have been in relaxation at constant elongation. One stress-strain curve has been taken with the machine continuously driven. Following extension of a specimen, Laue X-ray photographs were taken to obtain the orientation change between deformed and undeformed regions, recorded on a single film by translating the specimen in a plane normal to the beam between exposures. Sequences of such multiple exposures were made on some specimens to include the entire orientation range on one film. Slip Direction To obtain a maximum orientation change with a single slip system, crystals of very closely <110> axial orientation were used. The classic determination of slip direction rests on establishing that direc-

Jan 1, 1956

By P. de Vitry, Oliver Bowles

The conventional wire saw, introduced in the slate district of Pennsylvania by the Bureau of Mines in 1927, and used thereafter with remarkable success, consists of a three-strand steel cable having a diameter of 93/16 or 54 in. The equipment, methods used, and accomplishments have been described in previous reports.&apos;-I Similar wire saws have been used extensively in Europe, in quarries and in shaping blocks and slabs. During the period 1932-1937, competition in European marble quarries was keen, prices were declining, and orders were not abundant. When orders were received, there was generally an urgent call for speedy delivery. Because of the diversification of demands, it was impossible to maintain in stock marbles of the color, size, and thickness called for, therefore the material generally had to be fabricated after the order was received. The wire saw enabled stone mills to fill such orders promptly. With skillful handling, 7/8-in. slabs could be cut accurately and rapidly with this equipment. It was found, however, that, as the three-strand wire became worn, the cutting speed dropped rapidly and the cut became less accurate. To overcome these difficulties the junior author of this paper, after much experimentation, developed a new type of wire consisting of a single ribbon-shaped strand, twisted as shown in Fig. I. To ensure straight sawing, the twist of the ribbon is reversed from right to left and vice versa every 25 ft. The reversal of the twist is shown in Fig. 2. This is not a new feature; it has been used to advantage with the three-strand wire both in Europe and America for several years. However, some difficulties arise in splicing the three-strand reverse-twist wire, and the claim is made that cutting is less accurate as the wire becomes worn. To make an endless belt, the ends of the single-strand wire are brazed together with Pyrophyllite is a hydrous aluminum silicate (A1²Si4O10(OH)²)1 that, occurs in both the foliated and the massive forms. The foliated variety resembles talc in that it has a greasy feel, a pearly luster, perfect basal cleavage, and usually is white, although in some deposits apple green, gray, brown, russet, and nearly black specimens may be found. The massive deposits of pyrophyllite yield pearl gray to light tan aggregates, some of which are so friable that they may be crushed with the hands into a fine gritty powder. Frequently specimens of the massive variety are studded with crystals of radial structure. The mineral has a specific gravity of about 2.7 and a hardness of 1 on Mohs&apos; scale.&apos; The chemical composition of commercial pyrophyllite reflects the mineralogy of the deposits, which, according to Stuckey12 contain pyrophyllite and quartz, together with chloritoid, sericite, and a few other minerals of negligible importance. The latter, he says, (&apos;are noticed in but small quantities to the extent they might occur as accessory constituents of an igneous rock or as products of regional metamorphism or weathering. . . . Quartz is abundant everywhere except in the very best grades of pyrophyllite." Analyses of specimens from several deposits are listed in Table 1, showing that the silica content varies from 57 to 73 per cent and the alumina from 22 to 33 per cent. Oxides of iron and the alkaline metals are collectively present, with one exception, to an extent of about 1 to 1.5 per cent. Sources At present, North Carolina is the only commercial source of pyrophyllite, although the mineral has been found in small quantities in many parts of the world. The North Carolina deposits are in the "Carolina Slate Belt," which traverses the center of the state in a southwesterly direction. This belt varies from 8 to 50 miles in width. Two major deposits of pyrophyllite lie along its eastern boundary, in what is known as the Deep

Jan 1, 1942

By Gilbert Doan

AN extensive program of investigation is being carried out at Lehigh University in the study of arcs and arc welds of high-purity iron1, spon-sored by the Engineering Foundation. The part of that program reported in the present paper deals with welds made of high-purity iron in an argon atmosphere and for comparison with them welds made of the same iron in ordinary air. Welds of commercial steel also were made in argon and in air. The primary purpose of the study is to discover the basic physical constants of iron welds when not contaminated either by impurities in the iron or by the action of oxygen and nitrogen of the air during welding. Upon these constants can be founded such future studies as will determine what effects the various impurities and alloy elements present in steel have upon its welding characteristics, and what influence is exerted by the action of oxygen and nitrogen. The welding of steel involves such a multitude of variables, both of composition and of procedure, that development in the fabrication of this most important metal has necessarily been slow, wasteful, and in many instances discouraging. In the present investigation, the simplest possible condition has been selected; namely, iron practically free from contamination and a nonparticipating atmosphere, the inert gas argon. This simplification reduces the number of variables to a point where more rigid control of the system is possible. Although this study is significant for the contributions it makes to the science of steel fabrication, yet it is hoped that it will not be without value also in increasing knowledge of the nature and behavior of iron and steel in general. From the standpoint of open-hearth practice, and to

Jan 1, 1936