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By George A. Miller

ALTHOUGH the Andean mountain belt, which contains almost all the metal deposits of the other South American nations, does not enter Brazil, this country is rich in mineral resources, for in area it accounts for half the continent and geologically it contains almost all of the Brazilian Shield. This great mass of ancient rocks has been relatively stable for a long time and forms a great area of plateaus and highlands interrupted only by the syncline which carries the Amazon River across it to the sea. Lowland Brazil - the great flood plains of the Amazon. Tocantins, Paraguay, and Parana Rivers-is of no interest to the miner, and in fact supports but a small proportion of the country's population. The highland area is divided into unequal parts by the Amazon River; the north half is underlain by the north lobe of the Brazilian Shield which extends into Venezuela as far as the Orinoco, and into the Guianas, and is known as the Guiana Highlands. Mineralization appears to have been weak in the Brazilian portion of these hills. In fact most of the ore deposits are to be found in the States of Minas Gerais and Bahia, although the neighboring states of Sao Paulo, Pernambuco, and Piauhy can also boast of some deposits. Goias and Matto Grosso are as yet incompletely prospected but are considered to contain reserves for the future.

Jan 1, 1945

By Paul D. Merica, O. B. J. Fraser

PROBABLY the first metallic objects used by man were nickel alloys. In search for flints suitable for the fashioning of their rude tools, our paleolithic ancestors, some 25,000 years ago, quite likely may have come upon some of those heavy, metallic fragments that we now know as meteorites, which consist of an alloy of nickel and iron containing usually from 5 to 15 pct of nickel. Whether paleolithic man ever did discover and use meteoritic fragments, his sketchy records do not actually disclose. We do know, however, that such fragments have been found and used by peoples, particularly the North American Eskimos, for weapons and implements in just the same manner as stones, and prior to any knowledge by those peoples of the reduction of metals from ores. Meteoritic showers were recorded frequently in earliest times and the meteorites often were found and fashioned into useful objects. The ancient Arabic and other myths of "invincible swords fallen from heaven" seem thus to have had a very definite basis in fact, and such weapons, of meteoritic material, have actually been re- covered from archeological excavations. It thus seems probable that meteoric nickel-iron was found and used long before iron was recovered by smelting iron ores (perhaps about 1200 B.C.) and probably even before there was knowledge and use of bronze and gold. Although many centuries were to pass before nickel was first isolated, in 1751, from Swedish ores and recognized as an elemental

Jan 1, 1953

By T. A. Rickard

The notion prevails that writing is a knack, that the skilful use of the pen is a gift of nature. This is an error. Dogberry may be responsible for it; he said: "To be a well-informed man is the gift of fortune, but to write and read comes by nature". Because Dogberry said it, we may be sure that Shakespeare thought otherwise. Ability of any sort may be partly innate, but my own observation and experience lead me to conclude that most of the easy writers have become so by constant practice. As I recall the names of men successful with the pen, I remember that most of them have written a great deal and have taken particular pains to improve their style. The suggestion that proficiency in the difficult art is a happy accident provokes a sardonic smile. The larger part of the great writing in our literature is the result of persistent effort. An easy fluency has been the undoing of many; their flamboyant and fantastic scribbling has proved as perishable as froth. This criticism applies to technical writing also; in order that a technical description or discussion may hold the interest of the reader, at least long enough to cause him to read it to the end, the writing must be done carefully and systematically; otherwise it will fail in its purpose of conveying information. Clearness is absolutely essential. "It is not enough to use language that may be understood; it is necessary to use language that must be understood."* The purpose of writing, at least of that which is meant to be read by others, is not only to express ideas but to communicate them. Lack of perspicuity may prove as %ad as

Jan 1, 1931

By J. F. Myers, F. M. Lewis

C. G. McLACHLAN*-I have read this paper with considerable interest and wish to congratulate the authors on the care with which they carried out their experiments and for the detailed sizing data they have presented. 011 the other hand I do not feel that these data establish their contention that "with other factors the same, the work accomplished in a fine crushing rod mill is directly proportional to the rotating speed." My reason for making this statement is that their conclusion is based on the percentage of minus 65 mesh material produced at each of the speeds at which their tests were run. The rod mill is, however, not a fine grinding machine and therefore figures based on minus 65 mesh production are figures outside the range at which it operates to best advantage. Further, if rod mill performance is to be judged on the production of such material it should have been established that a rod mill will produce it as effectively as a ball mill. To check this last point I have gone over some of the rod and ball mill grind-ing figures for our Waite-Atnulet operation and find that the ball mill at that property produces more minus 65 mesh material per horsepower than the rod mill. Moreover, this comparison is even more favorable to the ball mill if it is limited to minus 100 mesh production. It therefore seems to me that the most satisfactory basis on which to try to com-pare the performance of the rod mill in the present case is by taking a weighted average of all the new surface produced per horsepower. W. H. Coghill3 has published data which can be applied to the sizing figures presented by the authors, and if this is done the units of new surface per horsepower produced in the Tennessee tests are as follows: Admittedly the increment of increase in new surface per horsepower shown in the foregoing figures is not great, but its trend is nevertheless definitely in favor of slower speed operation, for the conditions under which these particular tests were run. I also feel that some information regarding liner contour should have been given as I think it will be found that a mill which is equipped with liners which lift the rod load can be run at a slower speed than a mill in which the liners are comparatively smooth. J. F. MYERS and F. M. LEWIS (authors' reply)—The position taken by Mr. McLachlan is to be respected even though we are all aware of the faults of surface considerations. As he points out. the increment of increase is very small. It is so small in fact that for all practical purposes it does not conflict with the conclusions of the paper. The authors appreciate Mr. McLachlan's comprehensive study of the data.

Jan 1, 1950

By AIME AIME

ON May 5, the Washington, D. C., Section, A.I.M.E., devoted its meeting to the many-sided and perplexing question of mineral stock-piling for peace. Opening the symposium, Harry J. Wolf, of the War Production Board, outlined the problem under six heads: (1) Technical. Mechanical, chemical, or metallurgical importance of specified materials, emergencies that might arise, relative scarcity, and critical value of stock piles during emergencies. (2) Economic. Cost to Government, influence of Government stocks on commercial relationships and markets, effect of availability of items as a con¬structive influence on industry, Administration policies now and during postwar period. (3) Legislative. Need for immediate legislative action, need for legislation on postwar conditions as well as on current requirements, a constructive basic policy to prevent political manipulation. (4) Military. Consideration of re¬quirements and supplies bearing on national safety and needed for manufacture of equipment, and adequate reserves of scarce materials for research or experimentation by military agencies. (5) International. Interests of the United Nations in contradistinction to those of the United States; effects of nonisolation policy on nature, location, and administration of stock piles. (6) Negative stock-piling. Question of United Nations' legislation to prevent stock-piling by Axis nations after the war and who shall purchase stock-pile materials and during what periods.

Jan 1, 1943

By M. C. Flemings, A. A. Tzavaras

Analytical and experimental procedures are descrihed for quantitative determination of volume-fraction microporosity in metals by mimorarlio-graphg. The analysis assumes spherical pores but allows for the observed fact that pores or portions of pores smaller than a given thickness do not project an image on the film. Volume-fraction microporosity was measuured in cast low-alloy steel and shown to vary from 0.6 x 10-4 to 10 x 10 depending on mode of solidification and on whether the material was air- or vacuum-cast. The aim of work described herein was to develop a method of quantitative measurement of the volume fraction of microporosity in cast metals. Microporosity, present in nearly all castings and ingots, is always interdendritic in nature and may be large enough to be seen on a polished surface with the naked eye. More generally, it is smaller in size, and its detection more difficult. Three techniques might be considered for measurement of microporosity: 1) lineal analysis of a polished metallographic surface, 2) density measurement, or 3) quantitative microradiography. As will be shown later, volume fractions of porosity in directionally solidified castings may be the order of 10-4 to 10-3; such small amounts of porosity are difficult to identify and measure on a polished surface. Density measurement is also not a suitable technique (for alloys) when the volume fraction of porosity is low. This is because the density of the base metal is often not known within the necessary accuracy, due to microsegregation or partial phase transformations. In general, it is not possible to completely eliminate microsegregation without also altering the porosity. Because of the limitations of the foregoing techniques, quantitative microradiography was employed to determine amount of porosity. In recent work, microradiography has been found to be useful for qualitative measurement of porosity, including determination of size and shape of individual pores;&apos;)&apos; however, quantitative determination of amount of porosity has not been attempted. I) CALCULATION OF VOLUME-FRACTION POROSITY The following analysis employs procedures similar to those of Cahn and Nutting3 and Hilliard.4 Major simplifications are that pores are assumed to be spherical and to be present in sufficiently small quantities that no overlapping occurs. A basic difference from the previous treatments is that the limited "sensitivity" of microradiography is considered. Assume first 1) cavities are spherical and of uniform diameter, 2) cavities are randomly distributed, 3) volume-fraction porosity and specimen thickness to pore radius ratio are sufficiently small that overlapping of the projected images of cavities is negligible, 4) sensitivity is limited (i.e., holes or portions of holes of less than a given thickness do not project an image on the film). The sensitivity, is defined as: where 5 = minimum thickness of void from which an image will be projected on the film and t = specimen thickness. Now, from Fig. 1, it is possible to distinguish between two different types of holes. These are 1) holes whose centers lie within the region t/2 > X > 6/2, where X is distance from one surface of the specimen (positive into the specimen), and 2) holes whose centers lie within the region (6 — r) < X < 6/2, Holes whose centers lie outside X = (6 -r) project no image on the film. These two types of pores are considered separately below. Type 1 Pores. When 6 is greater than 0, the image of a spherical cavity of radius r appears on the film as a circle of radius a which is smaller than r. From geometry, Fig. 1: a2=r2-52/4 [2] where a = radius of image of pore on film and r = radius of pore. Since the pores are randomly distributed and spherical V =4/3pr2Nv [3] where V = volume fraction of voids and Nv = number of pores per unit volume and the number of images of Type 1 pores per unit area of film, N&apos;A, is

Jan 1, 1965

By L. W. Kempf, K. R. Van Horn

DURING the recent development of aluminum alloys for free-cutting screw-machine rod, it became desirable to know something of the solubility of lead and bismuth in liquid aluminum and in some aluminum alloys. The literature is not particularly helpful in supplying this information. These portions, therefore, of the constitutional relationships of aluminum-bismuth and aluminum-lead alloys were investigated by thermal analysis and by chemical analysis of samples taken from aluminum-rich melts in equilibrium with precipitated lead or bismuth. The solubility of lead and bismuth in some liquid aluminum-copper alloys was also investigated. Some consideration was also given to the solubility of these elements in solid aluminum. Among the earliest investigators of the aluminum-lead and aluminum-bismuth systems was Wright,1 who reported that melts of aluminum and lead formed two layers indicating limited liquid solubility. Under his conditions, the aluminum-rich layer was reported to contain 1.91 per cent Pb and the lead-rich layer, 0.07 per. cent Al. Subsequently, Pecheau2 found that in aluminum-rich alloy melts with more than 10 per cent Pb three layers were distinguishable. He reported that the middle layer contained from 3 to 10 per cent Pb. He also found that the melting point of aluminum appeared to be lowered slightly by the addition of lead. Gwyer3 investigated these alloys and found evidence of a slight lowering of the freezing point of aluminum by the addition of either lead or bismuth. He found no evidence of solid solubility in either case and made no attempt to determine the liquidus curves. Hansen and Blumenthal4 reported that the addition of lead distinctly lowered the solidification point of aluminum. They also found that bismuth lowered the melting point of aluminum. Guillet5 reported almost complete mutual immiscibility for the aluminum-bismuth alloys in the liquid state. Bohner6 examined the effect of various concentrations of lead and bismuth on the electrical conductivity of aluminum. He found decreases in conductivity on annealing at 500° C. as compared with the conductivity of the same alloys on annealing at 300° C.

Jan 1, 1938

By A. R. Troiano, E. A. Steigerwald, F. W. Schaller

The initiation of localized cracking in hydrogenated high strength steel was dependent on the developmeni of a critical hydrogen conceniration and relatively insensitive to the magnitude of the applied stress. The stress was believed to influence the deluyed failure process by providing the means for grouping the hydrogen. On the basis of an assumed distribution law the observed changes in the lower critical stress as a function of notch acuity, yield strength, and temperature were predictable over a significant range of these variables. THE phenomenological characteristics of delayed failure in high-strength steel have been comprehensively investigated and the behavior has been attributed to the strong embrittling action of hydrogen.1-3 Delayed failure or, as it is also termed, static fatigue, is the most sensitive means of detecting hydrogen embrittlement since it allows the maximum time for hydrogen diffusion during a test.3 The nature of delayed failure cail be aptly described by four parameters which are schematically depicted in Fig. 1. The upper critical stress corresponds to the rupture stress in a conventional notch tensile test. The lower critical stress or static fatigue limit is the stress below which no delayed failure will occur. The incubation period is the time required for the formation of the first crack and the fourth parameter is the failure time. An increase in hydrogen content, notch acuity, or strength level of the material increases the susceptibility for delayed failure by decreasing the lower critical stress, the incubation period, and the time to failure.lY3 A decrease in test temperature prolongs the incubation period in accordance with the lower diffusion rate of hydrogen, and also de-

Jan 1, 1961

By L. W. Kempf

DURING the recent development of aluminum alloys for free-cutting screw-machine rod, it became desirable to know something of the solubility of lead and bismuth in liquid aluminum and in some aluminum alloys. The literature is not particularly helpful in supplying this information. These portions, therefore, of the constitutional relationships of aluminum-ismuth and aluminum-lead alloys were investigated by thermal analysis and by chemical analysis of samples taken from aluminum-rich melts in equilibrium with precipitated lead or bismuth. The solubility of lead and bismuth in some liquid aluminum-copper alloys was also investi-gated. Some consideration was also given to the solubility of these elements in solid aluminum. Among the earliest investigators of the aluminum-lead and aluminum-bismuth systems was Wright,1 who reported that melts of aluminum and lead formed two layers indicating limited liquid solubility. Under his conditions, the aluminum-rich layer was reported to contain 1.91 per cent Pb and the lead-rich layer, 0.07 per cent Al. Subsequently, Pecheau2 found that in aluminum-rich alloy melts with more than 10 per cent Pb three layers were distinguishable. He reported that the middle layer contained from 3 to 10 per cent Pb. He also found that the melting point of aluminum appeared to be lowered slightly by the addition of lead. Gwyer3 investigated these alloys and found evidence of a slight lowering of the freezing point of aluminum by the addition of either lead or bismuth. He found no evidence of solid solubility in either case and made no attempt to determine the liquidus curves. Hansen and Blumen-thal4 reported that the addition of lead distinctly lowered the solidifica-tion point of aluminum. They also found that bismuth lowered the melting point of aluminum. Guillet5 reported almost complete mutual immiscibility for the aluminum-bismuth alloys in the liquid state. Bohner6 examined the effect of various concentrations of lead and bis-muth on the electrical conductivity of aluminum. He found decreases in conductivity on annealing at 500° C. as compared with the conductivity of the same alloys on annealing at 300° C.

Jan 1, 1938

By H. F. Yancey

Various criteria for evaluating the performance of coal washeries are discussed critically, with particular reference to ideas developed at the First International Conference on Coal Preparation held in Paris in June 1950. Criteria that relate only to the sharpness with which a cleaning unit separates coal from impurity are compared with those that reflect loss of coal or quality of products.

Jan 6, 1951

By G. Pizzi, G. M. Ciucci, G. L. Chierici

The use of the material balance equation to estimate the volume of hydrocarbons originally present in a reservoir, whose producing mechanism is partly due to water drive, has been discussed in the literature by several authors. There is no general agreement upon the possibility of obtaining reliable results by this method. Gas reservoirs in contact with an active aquifer are considered in this paper. Theoretical considerations based on the cybernetic principle of uncertainty (which states that the internal structure of a system cannot be uniquely determined from its observed external behavior) lead to the conclusion that the volume of gas originally present in a reservoir of this type cannot be uniquely determined from its past history. The range of values which encompasses the actual value of the reserves varies from case to case and must be determined by either numerical or analogical methods. Results obtained for six gas fields are reported. All these fields were produced with small fluctuations in their production rates, as is common practice for gas reservoirs; no gas storage fields were considered. Results obtained show that reserves values in a range of 1 to 2, associated with appropriate aquifers, allow the matching of the reservoir past history with mean-square deviations less than the experimental errors involved in pressure and produclion measurements. Similar results have been found in several other partial water drive gas reservoirs. From these results it is concluded that gas reserves cannot be uniquely determined from the past performance of partial water drive reservoirs, at least in cases where the reservoir has been submitted to small fluctuations in the production rates, and pressure data of normal accuracy are available. INTRODUCTION A number of authors have analyzed the problem of estimating the reserves originally present in a partial water drive reservoir from its past pressure-production performance. Literature which deals with this subject can be grouped, according to their conclusions, as follows. 1. A reliable value for the reserves can be obtained even if reservoir data (pressure and cumulative production) are affected by errors within the normal range.&apos;-&apos; 2. A reliable value for the reserves can be obtained only if reservoir data are very accurate&apos;- or if past production performance has been subjected to abrupt variations in the production rate."&apos; 3. No unique value for the reserves can be obtained from reservoir past production performance. This conclusion has been based upon theoretical considerations" and verified in several field cases. The purpose of this paper, which deals only with partial water drive gas reservoirs, is to test the above conclusions against actual field cases. Some theoretical considerations on this problem are also presented. THEORETICAL CONSIDERATIONS As the behavior of a gas reservoir communicating with an aquifer depends on both the aquifer and the reservoir characteristics, the physical system to be studied is the combined gas reservoir plus aquifer. The information which is available for studying the performance of such a system is the well production rates and bottom-hole pressures, all given as functions of time. The external behavior of the reservoir-aquifer system is therefore described by 2n input variables (Gp, Wp,) and n output variables (p,), n being the number of wells in the reservoir. In reservoir engineering it is common practice to consider the reservoir as a whole, disregarding the internal distribution of pressures and of producing wells. This practice is equivalent to substituting the above multi-variable system with a single-variable system, where the average reservoir pressure is the only output variable and the cumulative production G,(t) and W,(t) are the input variables. The internal structure of such a system, defined by initial gas reserves G, aquifer shape and dimensions, boundary conditions and petrophysical parameters distribution throughout the aquifer, is unknown. Therefore, from a cybernetic point of view the system is a "black-box It has been demonstrated" that for a blackbox the indetermination principle holds. Accordingly, the number of different internal structures (or set of parameters) which can account for the observed external behavior is infinite. As a consequence, the initial reserves cannot be uniquely determined from the reservoir past performance. When W,(t) is known, the determination of G from

By J. R. Campbell

A dozen years or so ago, the general superintendent of our company, now the president, Mr. W. H. Clingerman, asked me to study the coal-washing problem. This work brought me into contact with the best washery men of the country. I investigated many kinds of coal-cleaning schemes, made numerous tests, and collected voluminous data, yet I confess frankly that I have had little practical washery experience and that little has been at the Middlefork washery of the United States Fuel Co. at Benton, Franklin Co., Ill., which was put in operation last fall. While this washery installation may not be the "last word," I am quite sure it embodies some long steps in advance of the older designs and constructions. From the washery man&apos;s standpoint, the removal of pyrites or marcasite, a disulfide of iron, is the one vital problem, and the one productive of the most beneficial results, so far as elimination of sulfur is concerned. Sulfates and so-called organic sulfur occupy quite a sec-. ondary position and are generally lost sight of in coal washing. The elimination of sulfur in coal in the past has usually been accomplished by jigging in water, but lately concentrating tables have been successfully employed. The flotation process has been applied to fine coal, but is hardly considered practicable. Coal washing is rapidly coming into its own, due to the depletion of low-sulfur coals for coking purposes, and we predict that soon the same careful attention will be given to the design and construction of coal washeries that is now being given to byproduct plants and other allied industries. Heretofore, coal washing has been considered only an incidental and necessary evil instead of the big problem it is—one worthy of the most careful study by men well trained along technical lines and capable of delving into the fundamental principles. Preparation oF Coal It is usually necessary to crush the mine-run coal before sending it to the jigs, the degree of crushing depending on the occurrence of the sulfur and other impurities in the coal and the type of jig over which it is to be sent. The feldspar jig requires finer and more uniform crushing

Jan 1, 1920

By Gernot Kostorz

In a recent paper, Raffo and itcheell1 compared solid solution hardening of various bcc alloy single crystals at room temperature and concluded that the expression for localized elastic interaction between dislocations and solute atoms2 that gives the critical resolved shear stress (CRSS) 7,: to = Z . µE3/2 C1/2 where c = concentration, e = misfit parameter, (µ = shear modulus, Z = numerical constant Fig. 1—The slope dT0/dc1/2 for niobium alloy single crystals deformed at 570°K plotted against the misfit parameter € = In&apos; I + 1616 I. from Ref. 6, •estimated from Ref. 7. Table I. Plateau Hardening and Alloy Parameters for Niobium Alloys dT0/dc1/2, kg/mm2 Solute Ref. 6 Tantalum 3.7 ± 0.3 1.9 0.73 + 0.06 9 0.0 ± 0.5 15 Vanadium 16.1 ±1.4 - 0.69 i 0.01 9 -7.4 ± 0.5 16 Tungsten 12.5 ? 1.5 20.9 0.92 i 0.05 10 -5.0 t 0.4 17 Rhenium - 25.9 1.24 11.12 -8.5 ± 0.4 I5 Molybdenum - 14.6 1.04 13,14 -4.6 s†±?˜µ?fF?? 0.5 17 Hafnium - 13.9 0.37 12 4.8 ± 0.5 17 Table 11. Solid Solution Hardening and Alloy Parameters for Tantalum Alloys i)&apos; dTo/dc1/2 kg/mm2, dTp/dc1/2 kg/mm2, Ref. 22 1006 Solute ˜570°K Ref. 7 See Text Ref. 25 Rhenium 44.3 32.5 0.65 -8.5 Tungsten 32.1 24.3 0.34 -4.6 Molybdenum 29.3 19.1 -0.19 -5.9 Niobium 5.8 5.5 -0.43 0.I

Jan 1, 1970

By OTTO HERRES

UTAH has enormous deposits of high-grade bituminous coal. The United States Geological Survey estimates that there are 13,130 sq. mi. of land in Utah known to contain workable coal and these extensive fields contain 196,000,000,000 tons of coal. Growth in population and development of industry in the intermountain and Pacific coast regions will in time give Utah a place with the great coal producing states of the country. Even today, faced by adverse conditions in competition with cheap fuel oil from southern California, water-power throughout the western states in general, and comparatively high freight rates to its distant markets, the Utah coal industry is notable in many respects. In recent years, Utah has led the United States both in the percentage of its mines in class 1, mines producing more than 200,000 tons a year, and in average production per man per day, which was 6.01 tons in 1921. In Mineral Resources of the United States, 1921, Part

Jan 1, 1925

By W. H. Bassett, C. H. Davis

The late J. P. Sparrow, chief operating engineer of the New York Edison CO., carried out a series of practical tests on condenser tubes of several copper alloys and reported on the results to the Association of Edison Illuminating Companies at its meeting in September, 1913. In the preparation of these tubes the senior author had the pleasure of cooperating. Copper-zinc alloys in the proportions of 60-40,70-30,80-20, 90-10, and Admiralty metal, which is in effect 70-30 with 1 per cent. of tin, were tried. Monel metal and several copper-nickel alloys, and 8, 5, and 3 per cent. aluminum bronze were also tried. At the time of this report, the aluminum bronze had been in service for 4 1/2 years and seemed to be giving especially good results but later it began to fail and showed no substantial improvement over Admiralty metal. Monel metal was unsatisfactory and the nickel alloys apparently did not give better service than the Admiralty alloy. Previous to the publication of the report, and after considerable discussion, it was agreed that a test where tubes of different kinds could be under laboratory observation would be advisable, so the apparatus described here was set up in The American Brass Co.&apos;s Waterbury Laboratory. This was fitted with tubes of copper, brass, bronze, nickel silver, cupro-nickel and other alloys, and the test started on Oct. 11, 1912. Salt water from East River, New York harbor, was barrelled and transported to the laboratory for the test. A fresh supply, completely replacing the water in service, was obtained at the end of each six months period. Plan of Procedure In general, the procedure was to inspect the tubes at short intervals and to remove those that had begun to leak. The tubes removed were carefully examined and a photographic and microscopic record of the

Jan 1, 1925

By Virgil R. D. Kirkham

NoRth America has for many years led the world in phosphate production, but with development of African deposits and their marketing conditions with respect to European countries, this leadership will shortly pass to Africa. Algeria, Egypt, Tunis, and Morocco have large phosphate reserves and a correspondingly large production because of easy mining and a ready European market, which was developed during the war. An increase in home consumption is destined to develop for the eastern American fields, and the countries of the Pacific will provide a market for the western producers. New processes indicate a decrease in fertilizer costs, which will encourage a more widespread domestic use and assure better marketing conditions. The African deposits, although benefited by a water haul, have the disadvantage of being isolated from a source of acid so that the crude rock is shipped from Africa to its destination, whereas in the United States the chief product shipped is acidulated rock or various types of superphosphatic fertilizers, The principal types of phosphate deposits used in the manufacture of fertilizers are guanos, apatite, phosphatic marl, phosphatic limestone, phosphatic shale, and phosphate rock which is also known as phosphorite. Some of these deposits are found on each of the continents; Table 1 gives their occurrence, age, location, character, extent, etc. Most of the information found in this table represents a compilation of information published elsewhere in a different form and widely scattered.

Jan 1, 1925

By A. G. Loomis

IT is only within the past 10 years that serious attempt appears to have been made to improve rotary drilling fluids by the application of the principles of colloid chemistry, although the use of chemicals to control the rheological properties of clay slips has long been known in the ceramic industry. The main difficulty apparently lay in the lack of a complete analysis of all of the functions of a drilling fluid in the drilling of the well, together with the lack of adequate consideration of how colloid science could be applied to secure these ends, and particularly how apparent antithetical properties of the fluid could be compromised. Thus one analysis1 of the many requirements of a drilling fluid proved conclusively that the viscosity should be low, in order that cuttings and entrained gas might be eliminated effi-ciently in the settling ditch, while the loss in carrying capacity accompanying low viscosity could be regained by increasing either the density of the mud or the upward velocity of the mud stream in the annular space of the well, and the danger of sticking of the drill stem due to rapid settling in case of enforced suspension of drilling operations could be eliminated by enhancing the thixotropic properties of the fluid. The desired properties of the drilling fluid having thus been established, it was a natural step to treat the fluid with vis-cosity-reducing chemicals, such as salts of weak organic acids1,2-for example, sodium tannate or gallate-and to adjust the pH to the alkaline side to such a degree of thixo-tropy as would give low viscosity and low yield point under the conditions of flow prevailing in the settling ditch, but rapid gelation and high yield point when quiescent in the annular space during shut-downs. In fact, flow in the settling ditch should be just short of turbulent while flow in the well, together with the flow of mud past the cuttings, is practically always turbulent. The use of chemicals other than those mentioned, such as Calgon (sodium hexametaphosphate) and certain other phosphates together with sodium tannate, has now become standard practice and it is the consensus that this method of treatment has proved to be an important step in the development of the art of drilling oil wells.

Jan 1, 1940

By George W. Pawel

OWING largely to its value as a toughener and strengthener of steel for both industrial and military purposes, nickel is playing, an important role in the current war. It is fine of the metals in which the Allies enjoy a definite edge over the Axis nations and this time there is no place to which the Germans may send another submarine "Deutsehland" and expect to pick up a cargo of nickel to replenish their exhausted supplies. Total world nickel production thanks almost entirely to the expanded operation of the International Nickel Co. of Canada at Sudbury must now be at the rate of around 175,000 tons a year scarcely more than 5 per cent of which is accounted for by Germany, Italy and Japan. This represents more than four times the world output at the end of the first World War.

Jan 1, 1943

By Joseph L. Gillson

Bentonite, designating a distinct type of clay, is a young name in mineral nomenclature in the light of the age-old names of most other useful nonmetallics. The earliest references in literature are to "soap clay" (1873) "taylorite" (1888) and finally "bentonite" in 1897, from its occurrence in the Fort Benton series of rocks near Rock Creek, Albany County, Wyoming. Bentonite is a rock term and consists largely of montmorillonite clay. The latter name was proposed in 1847 for a plastic clay found at Montmorillon, France. A clay of apparently identical properties was described by Cronstedt of Sweden in 1788 and a number of other similar clays found in France were given other names in publications from 1853 to 1856. The mineral name montmorillonite was recognized by Dana in 1892. The recognition of "clay mineral" distinctions which led to the present-day classifications of clays by their chief mineral content, dawned in the early part of the twentieth century. Grim6 has aptly said: About 1924, Ross10 and some colleagues of the U. S. Geological Survey began a study of the mineral composition of clays that led to a series of monumental papers on the subject. By the early 1930&apos;s what has come to be known as the clay-mineral concept became firmly established in the minds of a great many people actively studying clay materials. The clay mineral concept designates the major clays as kaolins, montmorillonites and illites and by this concept bentonites are now defined as "fine-grained clays containing not less than 85 pct montmorillonite" and a wide variety of clays found all over the world are included in that classification. They could all properly be called "montmorillonite clays" but the common commercial name is bentonite. For a period of over forty years from the time of the earlier discoveries, bentonite was thought to be only the sodium type highswelling clay produced principally in Wyoming. By the clay mineral concept, non-swelling montmorillonite clays also became known as bentonite. In the trade there are two broad divisions-sodium bentonite, often called Wyoming or "western," which expands in water and carries sodium as its predominant exchangeable ion, and calcium bentonite often called "southern," which has negligible swelling and carries calcium as its principal exchangeable ion. There are many intermediate gradations. Properties The mineralogy and chemistry of the clays are so complex that the subject cannot be summarized briefly. The reader is referred to Chapter 12 of this volume in which the subject is treated at some length. Grim6 gave the formula for montmorillonite as (OH)4Si8AL4020.nH2O. He wrote: Montmorillonite is composed of units made up of two silica tetrahedral sheets with a central alumina octahedral sheet. . . . Exchangeable rations occur between the silicate layers. . . . The words "tetrahedral" and "octahedral" refer to the coordination number of the cations in the unit cell in the crystallographic lattice. Carroll5a stated: That the montmorillonite structure is the same as that of mica, but the layers are not held together by K+ ions; and water and other polar molecules, such as organic molecules, can enter between the unit layers and cause expansion. Ex-

Jan 1, 1960

By Bruce W. Gonser, Robert I. Jaffee

Recent work by the authors1 established the constitutional diagram of the gold-germanium system. Of particular interest in the simple euctectiferous system was the eutectic alloy at 12 per cent Ge, which melted at the very low temperature of 356°C and had an unusually fine eutectic structure. It was of interest to investigate the effect of third components on the melting point, microstructure, and strength of this alloy, and in this work the effect of copper is discussed rather completely, with less complete data on the effects of silver, platinum, nickel, and zinc. No reference in the literature has been found on ternary systems with gold-germanium. Materials and Alloying -4s in the work on the binary system, gold-germanium, the germanium used in this investigation was the cyanide-reduced, 99.9 per cent product, produced by the Eagle-Picher Co. Fine gold sheet from Handy and Harmon, pure platinum sheet from the American Platinum Works, copper magnet wire from Anaconda, nickel wire assaying 99.6 per cent Ni. and electrolytic zinc were used for alloying. To make the alloys, charges of the pure metals were put in a graphite crucible and melted in an atmosphere of pure hydrogen. The temperature was brought up to about I050 C, and the metal allowed to freeze in the crucible. Except with alloys containing zinc, melting losses were consistently less than a few milligrams. When zinc was a component, weight losses up to half the weight of the zinc present were incurred, and the alloy compositions were calculated by assuming the entire weight loss to be that of zinc. In all other cases the composition of the alloys could safely be taken as that of the charge. The ingots, as solidified, were segregated, the heavier primary phases being at the bottom and sides of the ingots and the lighter primary phases at the top, but by sectioning the entire ingot vertically for microscopic examination, this factor could be evaluated. Ingots for microscopic examination weighed one gram, and those for thermal analysis weighed three grams. Thermal Analysis In this work, the eutectic line composition and thermal arrests were desired, and, after microscopic exploration had established the position of the eutectic line at a given percentage of the third component, a thermal analysis was run at that composition. The method of thermal analysis used in the work on the binary Au-Ge system,&apos; a method particularly well suited for a small quantity of material, was used in this work. Clearly defined arrests were obtained, although with some alloys containing platinum

Jan 1, 1946