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By J. C. Bartlett

The following discussion was suggested by an experiment of Mr. Krom, the Manufacturer of air-jigs, to illustrate the superiority of air over water as a medium of concentration. The paper is written in the interest of no system of concentration, but simply to test the experiment, and, perchance, to add something to the general fund of information on the subject. To speak of testing an experiment by a theoretical discussion, may seem a misuse of terms, but the theories concerning falling bodies and the resistance of fluids are pretty well crystallized into laws, which may properly be used to show where experiments which seem to refute them were improperly performed, and that instead of refuting they only corroborate. It is well known that a sphere of galena & inch in diameter, and a sphere of quartz 1/2 inch in diameter, are equal falling in water ; that is, these two spheres, being placed together in a column of water at rest or in motion, will practically remain together, filling or rising together, or remaining in suspension. Mr. Krom, to show that these

Jan 1, 1879

By L. Kaufman

An equation is derived relating AF a", the difference in free energy between austenite and martensite, to temperature and composition in the iron-chrmnium and iron-chromium -nickel systems. This equation is used to calculate at M,for low-carbon stainless steels. A method for utilizing the energetic equations to calculate M, in stainless steels is suggested. In addition, an explanation is given for the anomalous effect of chromium in forming a y loop concurrent with the lowering of M, in iron-base alloys. It has been demonstrated that the effect of alloying elements on the Ms temperature is strongly dependent upon the influence of the alloying element on the thermodynamic properties of the y and a phases. Notwithstanding the fact that alloying elements affect the Ms temperature by changing the lattice parameters, elastic constants, and inter-facial energies of the a and y phases, their primary role is a thermodynamic one. Thermodynamic analyses have been presented for the iron-carbon'-4 and iron-nickele systems in which equations are derived for Fa and FY, the free energies of the b.c.c. (or b.c.t.) and f.c.c. phases. These equations, which can be obtained with the aid of the equilibrium diagrams, can be used to help predict the Ms vs composition curves. This paper deals with a calculation of the thermodynamic properties necessary to compute AFffLY for iron-chromium alloys. In view of the lack of direct information concerning the activity of chromium in the a and y phases of iron, the regular solution approximationa,g was utilized to bridge the gap. After the necessary equations were derived for the iron-chromium system they were used to calculate AFff— Y for stainless steels by combining them with the previous results obtained for iron-nickel alloys. The results of these calculations offer a means of rationalizing the anomalous behavior of chromium in iron-base alloys. The latter depends on the regular solution approximation in contrast to the explanation offered by zener , which is based upon the "magnetic specific heat effect." THERMODYNAMICS OF THE IRON-CHROMIUM SYSTEM If y represents the atomic fraction of chromium in an iron-chromium alloy, then the free energy of the b.c.c. phase Fa, the f.c.c. phase FY, and the difference in free energy between the f.c.c. and b.c.c. phases of the same composition are given through [3] and Fmy represent the free energies of mixing of the a and y phases; while @era -' and uFea 4Y represent the difference in free energy between f.c.c. and b.c.c. chromium and iron respectively. The values of AEFe0ff4Y in the temperature range between 0" and 900K ( .

Jan 1, 1960

By A. A. Smith, J. S. Smart

THE elements silver, cadmium, tin, antimony and tellurium either are found as impurities in commercial coppers or are intentionally added to produce coppers for special uses, When present in small quantities, each of these metals exerts a significant effect on the properties of copper, but despite considerable experience and investigation much remains to be learned about their specific behavior. The presence of extraneous elements, particularly oxygen, complicates the study of individual additions of impurities in the range 0 to 0.05 per cent, and the use of high-purity copper has been found extremely helpful in circumventing these difficulties. It has also been found that individual behavior can be satisfactorily determined from measurements of two commercially important properties, conductivity and softening temperature, according to methods that have been described previously.1,2 Data of this type, obtained in the course of a general investigation of the effects of impurities on the properties of both oxygen-bearing and oxygen-free copper are presented herewith. All samples except those containing cadmium were prepared as 3/8-in. continuously cast oxygen-free rod from pure copper and weighed amounts of a similarly synthesized master alloy. Composition was checked by chemical methods, which in every case verified the calculated analyses. Test wires were cold-drawn one B. and S. number per pass on a string-up machine using four 30-min. 600°C. anneals at 0.3125, 0.257, 0.204 and 0.162 in. and a final cold reduction of 75 per cent to 0.081 in. Some oxygen-bearing samples were produced directly from the 3/8-in. oxygen-free rods by diffusion from a surface scale at 850°C. and drawn to size as listed above, but most of the alloys were remelted in pure graphite and cast through air into a I-in. round mold, The slugs were then hot-rolled to 5/16 in., drawn to 0.162 in., annealed as listed above, and drawn to 0.081 inch. Conductivity wires were annealed for I hr. at 100°C. intervals between 300° and 800°F., using a hydrogen atmosphere for oxygen-free samples and purified nitrogen for the oxygen-bearing type, All samples were quenched from the annealing temperature in 10 per cent H2SO4 and conductivity was measured on a Hoopes bridge that had been checked against a Kelvin bridge. The softening temperatures represent the half-hard stage of the annealing curve as determined by a standard procedure.1 EFFECT OF SILVER Numerous excellent studies of the argentiferous coppers are found in the literature, and these have been adequately

Jan 1, 1943

By H. W. Camp

RESEARCH is defined, scientifically, as a "sys- tematic investigation of some phenomenon, and also a search for hidden treasures." Chemists tell us that the hidden treasures of petroleum are far richer than the .products which have been best known to us. However, these secrets will be discovered only through intensive and systematic, as well as scientific, industrial research. Indeed, the scope of the subject is so great that such an intensive research program should be assumed by a centralized organization supported by the petroleum industry as a whole. Such organization would assume the responsibilities for investigation of new products and development of markets for such products. Gasoline, the chief product of the petroleum industry, has become a cheap commodity. The continual un-controlled overproduction of crude petroleum, the in-tensive competitive condition in the marketing of petro-leum products and the increase of refining efficiency and installing of cracking facilities, have all combined to lower the market value of gasoline. The lower cost of gasoline has all been passed on to the purchaser in the form of lower prices so that today the most important product can scarcely be manufactured at a profit. In other fields, manufacturing industries have diversified their products when faced by a similar situation. Thus, they have been able to widen their marketing outlook. Why cannot the petroleum industry employ the same tactics ? Right now we are hearing much discussion concerning the development of a wider market for existing petro-leum products and new products for existing or prospec-tive markets. For instance, we can cite recent develop-ments for use of propane, butane, and ethylene. Butane has been found to be an efficient and inexpensive re-frigerant, especially adapted to home refrigerating sys-tems. Propane and butane fractions of natural gasoline may be shipped under pressure and may be used as a substitute for acetylene in cutting torches in connection with oxygen. There is a possibility of substituting butane for gas oil in the carbureting of coal gas, as we know that butane contains practically the gas enrich-ment as the same volume of gas oil and should prove to be a superior product for this function. Ethylene, a hydrocarbon present in cracked gases, is finding an outlet for the artificial ripening of green fruits. The following table . shows the more general use of petro-leum products as now established.

Jan 4, 1928

By Hermann Wedding

I ASK your permission to speak about a matter which is not of a specifically scientific nature, but more of a general-I might even say of an international-nature, and the international character which this city now presents must be my justification for introducing it. The Germans, very often, are thought to be an exceedingly warlike people, but I come to-day in the capacity of a peacemaker. Our German language is an original language; it is, therefore, a language in which it is impossible to change the meaning of a word at will. It may be, perhaps, easier in a combined language, as the English, to associate and to exchange meanings. Now, a word which we hear a great deal at the present day, is "Stahl," in English, "steel." This word means, in the German language, a substance which can be hardened. As the German literature, in relation to metallurgy, is the oldest of the modern world, this circumstance may give the German a right to ask for consideration. But I think, now, when the four languages, German, Swedish, French, and English, compete in rich metallurgical literature, it is very necessary to have uniformity in the nomenclature of iron, which would prove not only useful for science, but equally so for trade. For that purpose I propose to make the divisions of iron so that the word steel shall comprise a subdivision and not a primary division as formerly. Nature furnishes us iron mostly in the state of oxides, and if in any other condition, we must convert the ore into oxide before we can make iron. The oxides are always mixed with certain earthy substances called rock or gangue. The extraction of iron involves, therefore, the twofold process of the reduction of the iron, and im¬parting to it the amount of carbon necessary for technical purposes, and the separation of the reduced and carburized iron from the gangue. The reduction is always effected by carbon or carbonaceous substances (coke, anthracite, carbonic oxide, etc.), and the result is, according to the degree of heat employed, either malleable iron or a non-malleable iron. The process of making malleable iron in this way is called, generally, the direct process-in German, Rennarbeil. It produces the iron in a solid state with a fluid cinder. By this process our ancestors made all their iron, and it has been revived in various ways in modern times up to the process of Mr. Blair, so far as I know, always without commercial success. The

Jan 1, 1877

Your committee's secretary submits the following report, or summary, to the- members of the committee, in an endeavor to lay before them a general review of the information so far received and also his own knowledge .of the work as carried on at a number of plants, this being done in part to secure further information and suggestions from members and lead to a more effective means of furthering the work of the committee. It is suggested that more detailed data be compiled regarding engineering features involved, and that papers be contributed which will deal with the safeguarding of underground electrical installations. There are few operating companies which have not started a more or less systematic campaign to safeguard their employees from accidental injuries and unhealthful surroundings, but a great deal is to be gained by experience. All may welcome the advice and cooperation of those who have been actively engaged in the work and have demonstrated the results obtainable by organized effort, and it is, therefore, exceedingly gratifying to note the ready assistance and hearty cooperation rendered by the companies that may be truly termed pioneers in the movement. No solution of the safety problem is to be found in a strict standardization of methods, rules or devices, as' the various mining, milling and metallurgical practices present too' many conditions differing broadly in general principles, but some standard system embodying principles, already proven to be efficient should be created, which may be modified or elaborated to meet specific requirements of each individual. company, or to fit working conditions as they exist in the various mining camps throughout the country. An industrial plant is -primarily a business undertaking, therefore the economic side-of a safety or welfare campaign is of importance. Many small operators have been deterred from undertaking the work by their belief that it involved an expense beyond their means, and one that could not be counterbalanced by greater efficiency or saving along other lines. This idea is generally clue to a lack of knowledge of the actual costs of such work, and of the results secured by judicious selection of a method commensurate with the. size and nature of the opera-

Jan 1, 1917

By Grover J. Holt

Open-pit mining on the iron range has been in a stage of transition for several years from the standpoint of mechanization. The most radical change in open-pit mining methods was started in open-pit haulage in 1937 with the departure from the then standard system of locomotive and car transportation and the advent of the heavy duty truck as a replacement. The initial use of trucks was followed shortly by the first installation of a conveyor belt for open-pit ore haulage. The growth of the combination of trucks for gathering units delivering to a conveyor system for transportation out of the pit, has been rapid and this transition appears to have reached a peak in 1949 with locomotives and cars now being used in only a few of the largest open pits. One point which must be considered, if we assume that the maximum equipment change- over point has been reached, is that the largest pits have probably passed their peak of production. Future ore replacement must come from smaller pits wherein the truck conveyor system has done an outstanding job.

Jan 1, 1950

By Charles R. Keyes

Discussion of the paper of Charles R. Keyes, Bi-Monthly Bulletin, No. 19, January, 1908, pp. 1 to 31. BERNARD MACDONALD, Guanajuato, Mexico (communication to the Secretary*) :-Mr. Keyes's paper is very interesting to me because of my personal experience with the development of the ore-deposits of Lake Valley. Seeing that many of the important facts connected with the early history of the development of these mines are either now unknown, or have become more or less distorted, and thinking that it would be interesting as well as valuable to have these recorded as a historical supplement to Mr. Keyes's elaborate paper, I present the following narrative: In February, 1881, soon after the Atchison, Topeka & Santa Fé railroad made connection with the Southern Pacific at Denting, N. M., the Lake Valley properties were brought to the attention of New York and Philadelphia capitalists by John A. Miller, of Silver City, N. M. At that time silver was $1.10 all ounce and silver-mining was very attractive. Vast fortunes were being made in Leadville and other Colorado camps, and Tombstone was pouring out its millions. Lake Valley, like all' other mining-camps in their early history, had its drawbacks, but the railroad, then passing within 14 miles of it, mitigated many of these. The camp lay in the foot-hills of the Black range, in which the Apaches had their stronghold, and raided, when it suited their convenience, the surrounding country, killing the prospectors and pioneer settlers and stealing their cattle. This band of Indians was joined by the outlaws and desperadoes from the frontiers of Texas, Arizona, and Mexico, who collectively defied the United States soldiers, restrained, as the latter were, by the mollycoddles from the East. The brutality of the Indian raids through Arizona and New Mexico in those days would scarcely be believed now, but they stain in deep

Feb 1, 1909

By Orville R. Lyons

THE removal of moisture from coal has been a coal-preparation problem ever since the first wet-washing preparation plant was placed in operation. Today, when most of the coal produced in the United States is wetted at the working face when mined, or is cleaned by wet methods, the removal of moisture is a necessity for any one or a combination of the following reasons; (1) to avoid freezing difficulties during shipment, (2) to increase the B.t.u. content, (3) to effect savings in freight costs, and (4) to so improve the coal that it may be used for specific purposes-for instance, in the production of briquettes or the production of metallurgical coke-or so that it can be treated by dry cleaning methods. In general, the amount of water retained by coal particles varies with the size-consist of the coal. Fine coal has a larger surface area per unit weight than does coarse coal, so its capacity for retaining moisture is proportionately greater. The removal of moisture from coarse coal is relatively easy, while the removal of water from minus 10-mesh coal or finer is a major problem, usually requiring an individual solution at each preparation plant. As a result, a multitude of methods and a variety of equipment have been designed to solve both general and specific moisture-removal problems. Definitions In order that misunderstanding may be eliminated insofar as possible, it is necessary to define the terms to be used. The moisture content of any given increment of wet, washed coal is made up of two parts, inherent and surface moisture. Inherent moisture has been defined in various ways and as yet no standard definition has been agreed upon. However, in general, it is considered as the moisture that is present in the coal in the bed. The important point to remember is that coal with any amount of inherent moisture, whether 2 or 20 per cent, will appear dry if there is no surface moisture. Also important is the fact that inherent moisture can be removed, in part, by air drying at atmospheric temperatures. Surface moisture is that attached to the surface of the coal particles or that retained in cracks and fissures other than capillary openings in the coal substance. Essentially, insofar as the bituminous coal and anthracite indus-

Jan 1, 1950

By Y. C. Liu, G. A. Alers

Using X-ray pole-figure information and the single-crystal elastic constants, the angular variation of an elastic modulus in a polycrystal can be calculated and compared to measured clalues. This procedure has been used in the past to provide supporting ecidence for a particular choice of ideal orientations in the description o the X-ray pole figure. Since it is well-known that the absolute value oj an elastic modlus oj a poly crystal cannot be acczrralely calculated from the single-crystal elastic constants, there exists a serious question about the reliability oj this modulus method in the study of textures. This paper deriz-es sez3eral simple fornzulae for the ntzgular lariatiion of Young's modulus in the plane o a rolled sheet sing the same ssuinptions which lead to the lack oj detinztion of the absolute c'alre OJ the elastic ,nodulus. The vesults show that, although the absolute isallre oj Young's modulus depends strongly on the assumptions made, the shape of the modulus vs angle curve is not very sensitive to the assumptions and thus can be used reliably in texture studies. Exatzples oj' using this criteriotz are illustrated in the text. NeARLY all poly crystalline materials have some preferred orientation in the arrangement of their grains and hence exhibit anisotropy in their properties. This preferred orientation is usually measured and studied by X-rays which yield detailed information on the statistical distribution of grain orientations in the form of pole figures. The usefulness of these pole figures in theories of texture formation and in predictions of properties has come to depend almost entirely on the characterization of the pole figure by one or more ideal orientations. Unfortunately, this characterization is not unique and different authors often present different ideal orientations to characterize a given pole figure. In order to distinguish between these different choices of ideal orientations, it is necessary to go beyond X-rays and consider other physical properties which reflect the texture' simply because any choice of ideal orientations must predict correctly the observed anisotropy in all physical properties. The most common example of this procedure has made use of the angular variation of Young's modulus with respect to the rolling direction in the plane of a rolled sheet.3 4 Here the anisotropy can be measured easily and it can also be calculated from the single-crystal elastic constants and the chosen ideal orientation. Unfortunately the methods used to calculate this anisotropy were chosen for their simplicity rather than for their mathematical rigor so that there exists a serious question as to the validity of conclusions reached by this modulus method. It is well-known5 that the absolute value of the Young's modulus of a polycrystalline aggregate cannot be calculated very accurately because different mathematical averages over the grains yield different results. It is one purpose of this paper to examine the effect of different averaging procedures on the calculated anisotropy of Young's modulus in the rolling plane of rolled sheets in order to see if this property can be used reliably in texture studies. This particular modulus and type of material were chosen because the modulus is easily measured and rolled sheet is technologically important. The results show that, although different averages yield different absolute values for Young's modulus, the shape of the modulus vs angle curve is not very sensitive to the averaging procedure and thus can be used as a criterion to check the various ideal orientations used to characterize the X-ray pole figure. Examples of this checking procedure are given in the final section. Another purpose of this paper is to examine the possibility of using the anisotropy of Young's modulus as an indicator of texture without reference to pole figures or ideal orientations. Such a use would require that different textures yield quite different shapes for the modulus vs angle curve so that the distinction between textures would be quite clear. The experimental results presented in the final section indicate that there is easily enough variation in shapes to allow modulus measurements to be useful texture indicators, par-

Jan 1, 1967

By J. Y. Oldshue

INTRODUCTION The field of fluid mixing involves many different kinds of process objectives. In order to classify these objectives, Table 1 gives a listing of five basic application categories, gas-liquid, liquid-solid, liquid-liquid, miscible liquids, and fluid motion. However, each of these areas can be broken up into two different concepts one involved with uniformity of solids or liquids as a criteria, and the other involved with chemical reactions or mass transfer. The things that we would do to design a fluid mixing for solid suspension are quite different from things that we would do to design a mixer for heat transfer or gas-liquid mass transfer. Therefore, there are really ten separate mixing technologies. Each of these areas has its [ ] own principles of fluid mechanics, scale-up techniques and application experience. We will take a look at each of these areas and look at some of the ways that we can handle fluid mixing applications which.

Jan 1, 1979

By A. L. Bailey, B. A. Landry

W. W. ANDERSON and G. E. KELLER*—We want to compliment the authors on this very thorough paper. It gives information which the coal industry has needed for some time. We hope that the additional information which the authors are collecting will he available shortly. The mixing and riffling procedure that was followed for experimental purposes is obviously not practical in routine float-and-sink testing because of the particle size degradation which would result in handling the sample so many times. It is important to obtain our tloat-and-sink fractions with a minimum amount of handling of material. A statement is made in the paper (p. 80) that "the variable most likely to affect the size of sample required to meet a given preassigned accuracy would be the state or degree of mixing of the coal." We agree that this is a large factor, but do not believe it is the most important factor. Our own opinion is that the most important single factor governing the total gross weight of sample that must be collected is the percentage of the weight of material in the smallest fraction that results from the screening and float-and-\ink operations. In other words, size of sample is governed by the total number of fractionations that must he made, and the distribution of material within the fractions. We can imagine a coal with perfect mixing, but with such a small amount of material in some float-and-sink fraction in one of the coarse sizes that a much larger sample would have to be taken than would be the case with very poorly mixed material, but with a large percentage of coarse material more evenly distributed in all float-and-sink fractions. Our own observation of many float-and-sink tests that we have run in our own organization on many types of coal is that the size of sample that must be used on fine size float and sink is governed more by the requirements for weight of material to be used for analysis in the laboratory than by weight of material necessary to obtain accurate float and sink percentage of weight values. In other words, it is our opinion that very small samples can be used for float-and-sink fractionation in the fine sizes, but that accurate analysis of the fractions will depend on a larger weight of sample being pulverized for the laboratory than is necessary to establish the float-and-sink distribution with respect to weight. A. L. BAILEY and B. A. LANDRY (authors' reply)—The authors thank Messrs. Anderson and Keller for their comments based on long experience. It is agreed that the involved mixing and riming technique used may be disadvantageous from the standpoint of degradation. Fortunately, the paper does point out that the extended riming was unrewarding in causing further mixing. Two large unknowns remain, however: (1) how much of the mixing from the presumed highly unmixed state in the bed was achieved toward the random state during blasting, loading, transportation, screening, and further transportation to the point where the gross sample was taken, and (2) how much of the mixing took place during the preparation described preceding riming. As has been pointed out by one of the authors.6 the degree of mixing has a very large effect on the size of sample required and there are still too few experimental data to show at what stage of coal handling most of the mixing occurs. The discussion states that the weight of material in a screened fraction, or in a float-and-sink fraction, is more important than the mixing factor. We do not believe that these factors are comparable in this instance inasmuch as our purpose was to give minimum sampling requirements to achieve a preassigned accuracy in the percentages of float, middlings, or sink, and nothing more. The gross sample had already been screened and no further division by screening was made or contemplated; also, it was not intended that the middlings and sink fractions would necessarily be adequate for percentage ash or other determination. In other words, the sample obtained by the method outlined is not intended for washability studies but only for preparation plant control. Further experimental work has been done, since the paper was prepared, to investigate the effect of increasingly larger top and bottom sizes on the variability of float, etc., of a double-screened coal from Western Pennsylvania. Results will be published and eventually attention is to be given to the preparation of sampling specifications. E. H. M. BADGER*—I should like the authors to explain more fully the fundamental assumptions on which their Eq 4 is based. The equation is of the form s2 = p(l - p) which is the usual expression for the (standard deviation)2 when the chance of finding a particular kind of particle in the sample is proportional to the number fraetion, p. But instead of the number fraction, the authors have used the weight fraction, WF/W. The chance of finding a particular kind of particle in the sample can only be proportional to the weight fraction, if the average ?eig?ts of all kinds of particles, that is, float, midlings, or sink, are the same. Surely a much more justifiable assumption would be that the average volumes of the particles are the same, and, if this is so, Eq 4 would not be true. This may be demonstrated as follows: Let be the weight fraction of float, middlings, or sink, dl the density of this fraction, and d2 the density of the rest of the coal. Then assuming that the average volumes of the pieces in the three classes are the same, the number fraction, p, is given by ? P = d1/l-?/d2 + ?/d1 = ?d2/d1 + ?(d2-d1) The weight fraction, w, in terms of p is given by ? = pd1/(l-p)d2 + pd1 = pd1/d2 + p(d1-d2) _____ [61

Jan 1, 1950

By A. Totani, S. Nakajima, H. Okazaki

The phase diagram for the SnTe-SnSe system has been studied in the temperature range from 300° to 900°C by differential thermal and quenching techniques. The X-ray measurements were made on quenched specimens. High-temperature diffraction was also made to study the phase transition in SnSe. The system is proved to be of a eutectic type in which no intermetallic compound exists. The eutectic point is at the composition SnTeo.55 Seo.45. the eutectic temperature being 755°C. Solid solubility limits are SnTeo.6Seo.r and SnT eo. 3s Seo.6s at the eutectic temperature, and change almost linearly to SnTeo.aaSeo.lz and SnTeo.18 Seo.az as temperature decreases to 300°C. It was shown that the SnSe phase has a phase transition of the second order at about 540°C and that the transition temperature decreases with increase of the SnTe content. THERMOELECTRIC properties of tin telluride (SnTe) and tin selenide (SnSe) have been studied extensively in recent years. The variation of physical properties with composition could be of interest if these compounds form an appreciable crystalline solution. The purpose of present investigation is to confirm the formation of crystalline solution or intermetallic compound, if any, and to establish the phase diagram for this system. The crystal structure of SnTe is NaCl type with a cubic unit cell1 (a = 6.313A). The crystal of SnSe having an orthorh2mbic unit cellz (a = 11.496, b = 4.1510, and c = 4.4437A) is isomorphous with tin sulfide (SnS) which has a distorted sodium chloride structure. It has been known that SnSe has a phase at at 540°C; the transition has been assumed to be of the second order. As far as we know, only two studies on the SnTe-SnSe pseudobinary system have been reported. The conclusion obtained in these papers is that, in the composition regions near SnTe and SnSe, the system forms a crystalline solution of the SnTe structure and the SnSe structure, respectively, and that, in the intermediate region, both phases coexist. However, neither the variation of the solid solubility vs the temperature nor the liquidus and solidus were investigated. Hence present writers have attempted to determine the phase diagram of the system by differential thermal analysis (D.T.A.) and X-ray diffraction. EXPERIMENTAL Sample Preparation. Starting materials, SnTe and SnSe, were prepared by the direct fusion of commercially available high-purity (99.999 pct) elements. Stoichiometric amounts of each couple Sn-Te or Sn-Se were weighed into a clear fused silica ampule. After evacuation to a pressure below 10-3 mm Hg, the am- pule was sealed, and annealed at 900°C for 5 hr. The melt was quenched in water. X-ray analysis confirmed the formation of a single phase of SnTe or SnSe. The other samples, SnTel-,Sex were synthesized from these SnTe and SnSe by mixing them in the required ratio, followed by annealing at 900°C and quenching. These samples were used directly for D.T.A. For X-ray measurements, samples were annealed at 700°, 600°, or 500°C for 100 hr or at 300°C for 150 hr, and then quenched in water. It was found that the lattice constants of the SnTe phase annealed for 150 hr at temperatures above 500°C did not differ from those annealed for 100 hr at the same temperatures. However the X-ray phase analysis showed that at 300°C the annealing for 150 hr was necessary to attain a true equilibrium state. D.T.A. The solid-liquid equilibrium temperature was determined from D.T.A. measurements. The sample was sealed in an evacuated silica tube and molybdenum powders sealed in an another tube were used as a reference material. The sample and the reference tube were placed in a nickel block and were heated from room temperature to 900°C at a rate of 3°C per min and then cooled down at the same rate to 600°C. Thermocouples for these measurements were Pt-Pt. Rh (10 pct) and the error of temperature measurements was within + l0C. D.T.A. curves were obtained on a two-pen recorder and an automatic controller (PID type) was used for the program of heating and cooling. When temperature reaches the solidus from the low-temperature side, there appears an endothermic peak. The solidus temperature was determined by extrapolation of the straight portion of the starting flank of this peak to the base line. In a similar way, the liquidus temperature was determined from an exothermic peak on D.T.A. cooling curve. In the case of supercooling, if any, its degree can be estimated from the magnitude of the abrupt temperature rise. X-Ray . X-ray powder patterns were taken by a diffractometer using CuK, radiation. Since the SnSe crystal is cleaved easily, the powders become flaky when SnSe-rich samples are ground in an agate

Jan 1, 1969

By D. E. Etter, J. E. Selle

HIGH-PURITY cerium metals, supplied as 99.9 pct pure, by various suppliers, vary widely in melting points and in the shapes of the differential thermal-analysis curves obtained as the samples are heated. A definite correlation is noted between the melting point, amount of premelting, and the number of inclusions present in the material. Briefly, the DTA apparatus, previously de-

Jan 1, 1964

By W. Mostowitsh

I. Introductory LEAD sulphate occurs as anglesite, and is formed in every roasting of lead sulphides or sulpho-salts containing lead. In smelting in the blast furnace an ore containing natural or artificial lead sulphate, a large part of the sulphur present goes to the formation of the intermediary product matte which requires further treatment for the recovery of the values it contains. It is therefore of importance to study the behavior of lead sulphate at elevated temperatures, both without and with reducing agents, especially as the information available gives data which are more or less conflicting. II. Decomposition of Lead Sulphate by Heat The dissociation of PbSO4 into PbO and S03 or S02 and 0 has been discussed by many metallurgists. The following data are considered to be representative. Doeltz and Graumann1 found that PbSO4 was not affected by heat at 800° C.; that dissociation began at 900° C., and was rapid at 1,000° when the salt lost in 1 ½ hr. 14.3 per cent. of its weight, the dry salt containing 26.43 per cent. SO3. Hofman and Wanjukow2 summarize their work upon the dissociation of metallic sulphates with the statement that the decomposition of PbSO4 begins at 195° C., but progresses very slowly, with the formation of the basic salt 6PbO.5S03 at 705°; that this salt undergoes a transformation at 847°, begins to be decomposed at 888°, to sinter at 896°, and to fuse at 910°; rapid dissociation begins at 952°, and is accompanied by volatilization of PbO; retardations at 958° and 962° indicate an acceleration of decomposition which, however, is not complete. Proske3 found that PbSO4 gave off at 900° C. in 30 min. only 0.63 per cent. of its SO3, and that the loss increased with

Jan 5, 1916

By T. A. Read, M. W. Burkart

The crystal geometry of the cubic-tetragonal interface after partial transformation of an indium-thallium alloy single crystal is described and a general theory is presented. The effects of applied stresses on this transformation are interpreted and the latent heat of transformation is obtained from observations of transformation under stress. A DIFFUSIONLESS phase transformation between face-centered cubic and face-centered tetragonal structures has been reported for the indium-thallium system by Bowles, Barrett, and Guttman1, 2 The transformation takes place at approximately 105 "C at 18 atomic pct Tl and 25°C at 23 pct Tl. In their study, Bowles, Barrett, and Guttman used poly-crystalline samples whereas in the present study single crystals were used to eliminate the transformation constraints imposed by adjoining grains. The use of single crystals made possible a comprehensive study of the effect of stress on the transformation. In the course of the work, it was possible to formulate a new method of analyzing dif-fusionless transformations (presented in this paper) which permits calculation of the geometry of the interphase interface from a knowledge of the crystal structures of the initial and final phases. The specimens were prepared from chemically pure thallium and 99.97 pct In which were weighed out to produce 3 to 4 grams of alloy of the desired concentration. The metal was placed in clean fused silica tubing, then melted, degassed and sealed under vacuum. (To obtain single crystals, it was found that both degassing and extreme cleanliness were essential.) Single-crystal specimens were grown by a modified Bridgman technique.8 pecimens were removed from the tube by dissolving the quartz in concentrated hydrofluoric acid which attacks the specimen very slowly. The specimen then was polished mechanically to produce four flat surfaces, electropolished, and annealed at 140°C for 48 hr. The electropolishing solution used was that described by Bowles, Barrett, and Guttman and the polishing was carried out on both the high and low temperature phases of the alloy. The high temperature polishing was done at 110°C with a stainless steel cathode. Visual Observation of the Transformation in Single Crystals A visual study of the transformation was made on specimens which had been electropolished in the high temperature phase. The specimens were supported on the stage of a metallograph by an electrically heated holder which contained an opening for observing the specimen. Visual evidence of transformation was found in the presence of an interface which separated the two phases. The interface plane defines the boundary of the phase undergoing transformation and manifests itself by the sharp change in angle between the surface of the specimen and the incident light at the juncture of the two phases. On slow cooling, well-annealed specimens transformed from the face-centered cubic structure to the face-centered tetragonal structure by the motion of a single plane interface which traversed the specimen from one end to the other. Upon heating, the interface moved back in the reverse direction. The interface could be started, stopped, or reversed at will. A temperature hysteresis of about 31/2oC was observed in the reversal of the interface. Holding an interface stationary caused it to disappear completely in most cases, whereas in other instances the interface became less distinct depending upon its orientation. The interface could be made to reappear by changing the temperature of the specimen. The low temperature tetragonal structure exhibits only the fine markings or subbands reported by Bowles, Barrett, and Guttman and is illustrated in Fig. 1. These subbands are twin-related. Back-reflection Laue patterns show the breakup of the cubic spots into pairs of spots corresponding to the twin orientations of the tetragonal phase.

Jan 1, 1954

By E. Gilpin

The following notes may serve to bring before your Institute an idea of the iron-ore resources of Pictou County. Enough work has been done to permit an estimate to be formed of their quality and probable extent. As yet the systematic mining and smelting of ironore in Nora Scotia is confined to the operations of the Steel Company of Canada, in Colchester County. Although the locality I am about to describe appears, in many respects, well adapted to iron smelting, etc., no attempts have yet been made to begin work. Nora Scotian capital is more readily turned to lumbering, fishing, and shipping ventures; and such an investment appears equally foreign to the rest of the Dominion. I need not, however, go further into this part of the subject, and can only hope that my notes may prove serviceable as indicating a probable field for future development. The accompanying map shows the position of the harbor of Pictou relative to the coal and iron-ore fields, and to the railways which intersect them. The branch of the Intercolonial Railway, running from Truro to Pictou, forms the western boundary of the iron-ore district, which extends beyond the point where the New Glasgow and Cape Breton Railway crosses the French River. The iron-ore district may be roughly described as a triangle formed by the ore-outcrops and the two railways, the former making the base, and the latter the sides of the triangle, the apex resting on the coal-field at New Glasgow. The drainage of the country is toward the Gulf of St. Lawrence, through the Middle, East, Sutherland's, and French rivers; and the surface is undulatory, seldom exceeding two hundred feet above the sea-level, except in the district lying between Glengarry and the upper waters of the French and Sutherland's rivers, where a maximum height of about five hundred feet is reached at several points. Geologically speaking, the district embraces two divisions, the Carboniferous and the Silurian, the latter resting on strata provisionally considered to be of pre-Cambrian age. As no geological

Jan 1, 1886

By A. A. Smith, J. S. Smart

THe elements silver, cadmium, tin, antimony and tellurium either are found as impurities in commercial coppers or are intentionally added to produce coppers for special uses. When present in small quantities, each of these metals exerts a significant effect on the properties of copper, but despite considerable experience and investigation much remains to be learned about their specific behavior. The presence of extraneous elements, particularly oxygen, complicates the study of individual additions of impurities in the range o to 0.05 per cent, and the use of high-purity copper has been found extremely helpful in circumventing these difficulties. It has also been found that individual behavior can be satisfactorilv determined from measurements of two commercially important properties, conductivity and softening temperature, according to methods that have been described previously.1,2 Data of this type, obtained in the course of a general investigation of the effects of impurities on the properties of both oxygen-bearing 2nd oxygen-free copper are presented herewith. All samples except those containing cadmium were prepared as 3/8-in. continuously cast oxygen-free rod from pure copper and weighed amounts of a similarly synthesized master alloy. Composition was checked by chemical methods, which in every case verified the calculated analyses. Test wires were cold-drawn one B, and S. number per pass on a string-up machine using four 30-min. 600°C. anneals at 0.3125, 0.257, 0.204 and 0.162 in. and a final cold reduction of 75 per cent to 0.081 in. Some oxygen-bearing samples were produced directly from the 3/8-in. oxygen-free rods by diffusion from a surface scale at 850°C. and drawn to size as listed above, but most of the alloys were remelted in pure graphite and cast through air into a I-in. round mold. The slugs were then hot-rolled to 5/16 in., drawn to 0.162 in., annealed as listed above, and drawn to 0.081 inch. Conductivity wires were annealed for I hr. at 100°C. intervals between 300' and 800°F., using a hydrogen atmosphere for oxygen-free samples and purified nitrogen for the oxygen-bearing type. All samples were quenched from the annealing temperature in 10 per cent H²S04 and conductivity was measured on a Hoopes bridge that had been checked against a Kelvin bridge. The softening temperatures represent the half-hard stage of the annealing curve as determined by a standard procedure.' Effect of Silver Numerous excellent studies of the argentiferous coppers are found in the literature, and these have been adequately

Jan 1, 1943

By A. A. Smith, J. S. Smart

THe elements silver, cadmium, tin, antimony and tellurium either are found as impurities in commercial coppers or are intentionally added to produce coppers for special uses. When present in small quantities, each of these metals exerts a significant effect on the properties of copper, but despite considerable experience and investigation much remains to be learned about their specific behavior. The presence of extraneous elements, particularly oxygen, complicates the study of individual additions of impurities in the range o to 0.05 per cent, and the use of high-purity copper has been found extremely helpful in circumventing these difficulties. It has also been found that individual behavior can be satisfactorilv determined from measurements of two commercially important properties, conductivity and softening temperature, according to methods that have been described previously.1,2 Data of this type, obtained in the course of a general investigation of the effects of impurities on the properties of both oxygen-bearing 2nd oxygen-free copper are presented herewith. All samples except those containing cadmium were prepared as 3/8-in. continuously cast oxygen-free rod from pure copper and weighed amounts of a similarly synthesized master alloy. Composition was checked by chemical methods, which in every case verified the calculated analyses. Test wires were cold-drawn one B, and S. number per pass on a string-up machine using four 30-min. 600°C. anneals at 0.3125, 0.257, 0.204 and 0.162 in. and a final cold reduction of 75 per cent to 0.081 in. Some oxygen-bearing samples were produced directly from the 3/8-in. oxygen-free rods by diffusion from a surface scale at 850°C. and drawn to size as listed above, but most of the alloys were remelted in pure graphite and cast through air into a I-in. round mold. The slugs were then hot-rolled to 5/16 in., drawn to 0.162 in., annealed as listed above, and drawn to 0.081 inch. Conductivity wires were annealed for I hr. at 100°C. intervals between 300' and 800°F., using a hydrogen atmosphere for oxygen-free samples and purified nitrogen for the oxygen-bearing type. All samples were quenched from the annealing temperature in 10 per cent H²S04 and conductivity was measured on a Hoopes bridge that had been checked against a Kelvin bridge. The softening temperatures represent the half-hard stage of the annealing curve as determined by a standard procedure.' Effect of Silver Numerous excellent studies of the argentiferous coppers are found in the literature, and these have been adequately

Jan 1, 1943

By Henry N. Doyle

Basic procedures in the mining industry have changed only slightly over the centuries since metals and fossil fuels became an essential part of man's economic and cultural life. Mining techniques of the 20th century bear a close resemblance to those of the ancients: exploration, ore breakage and removal, hoisting, and processing. The great advances, however, have been in equipment and machinery of greater size and speed which allow greater efficiency in each of these operations, with a corresponding reduction in manpower requirements. Yesteryear production was measured in pounds per man-day; today a giant and complex, but highly efficient, continuous mining machine can remove as much as eight tons of material a minute from the coal face. If our energy and metal demands of the future are to be met, and at this time it can be assumed that coal will continue to supply a significant part of the energy demand, other dramatic and spectacular technologic advances must be accomplished. Along with mechanization, however, public policy will require the industry to place greater emphasis on health and safety protection, as has been well demonstrated by recent actions of Congress. Together, fossil fuels and metals formed the basis for the industrial revolution-coal to develop power and metals to transform power into useful energy. Strangely enough, however, the mining industry the world over has lagged behind the continuous social changes brought on by the industrial revolution, such as preventive health and industrial hygiene services, and other programs directed to the well-being of the worker. In some countries this resistance, to change may have led in part to the nationalization of the coal industry. Whether this disinclination to social change in the industry of the United States reflects managerial attitudes, inept labor leadership, government neglect, or economic relationship would be the subject of an interesting study. Doubtless the mores of miners and their resistance to change, as well as their geographic isolation from other industrial groups, may have had a strong influence on these factors. In every major coal mining country the accident rate in the coal industry is substantially higher than other industrial groups, and the cost of pneumoconiosis compensation in some countries is greater than the combined costs for all other occupational diseases from all other industries. The high social cost of occupational accidents and diseases may have been a factor in the closing of the industry in at least two countries. Despite diminishing manpower needs, the industry is faced with critical manpower shortages. Miners once reared their sons to be miners; now it appears that the opposite is true. This factor alone, however, does not explain an acute labor shortage in the industry. Traditionally, the industry drew much of

Jan 1, 1976