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By E. R. Force, W. F. Cannon

Many large high-grade manganese deposits occur in marine-transgressive sedimentary sequences deposit fed on stable platforms, although the manganese mineralogy varies from carbonate to oxide facies and host lithologies vary from carbonate- to clay-dominated sections. Examples include the Nikopol and related deposits of the Soviet Union and Groote Eylandt, Australia. Recent work has shown that high sea-level stands are synchronous with stratified and stagnant oceans. We suggest that during transgressions and consequent anoxic events, the anoxic deep waters rich in dissolved manganese were dilute ore-forming fluids. Manganese was precipitated on the oxidized side of oxidation and alkalinity interfaces on shallow shelves. Where the precipitate was preserved, manganese ac- cumulated into ore deposits. Sedimentary manganese deposits have not been widely explored for in North America, nor are they always obvious in outcrop. Large areas of North America are underlain by rocks that we consider broadly favorable for such manganese deposits, and the disparity between the high potential but significant reserves of the United States is difficult to reconcile. Important undiscovered deposits seem likely. An area of Cretaceous rocks in South Dakota is presented as a possible location for a United States deposit analogous to foreign deposits described herein.

Jan 1, 1983

TO THE BOARD OF DIRECTORS AND THE MEMBERS OF THE AMERICAN INSTITUTE OF MINING AND METALLURGICAL ENGINEERS Gentlemen -It is pleasant to be able to report that the year just closed has been a prosperous and successful one for the Institute As is shown by the reports of the Treasurer and the Finance Committee, the business affairs of this organization are in excellent condition With property valued at more than three-quarters of a million dollars, and with con¬siderable sums in various funds and endowments, it is possible to spend on each member of whatever class $22 65 each year, more than the maxi¬mum amount of dues received from any one, and substantially twice the average amount, $10.94, received from all To do this has required close management and a strict regard for our limitations In 1926, when the Budget was made up, the estimated expenditures for the work which it was felt the Institute must do exceeded the estimated receipts by some $14,000. At the close of the year, despite a` number of unexpected decreases in receipts, it had proved possible to accomplish substantially all the work laid out and close the books with the usual transfer of initia¬tion fees to the General Reserve, and still only reduce the cash balance $2,074 54. This was made possible by the hearty and loyal cooperation of the whole staff of employees and the extremely large amount of gratui¬tous service rendered by the officers, the members of the Divisions and technical Committees, and the membership generally Even so it was impossible, because of limitations of funds, to undertake many things it is highly desirable for the Institute to do, and it was necessary to refuse the publication of important papers and committee studies, because of the lack of funds.

Jan 1, 1923

By R. Crnojevich, J. L. Blanco, C. Nikolic, W. G. Sherwood

This paper describes the process used for cobalt purification and recovery at the AMAX Nickel Refining Co. plant In Port Nickel, Louisiana In the first stage, cobaltic precipitate produced in the Outokumpu electrolytic nickel cobalt separation process is dissolved using methanol and sulfuric acid liquor produced in this step is converted to an ammoniacal complex, and sufficient ammonium sulfate is added to facilitate cobalt oxidation to cobaltic pentammine Nickel is then selectively precipitated as nickel-ammonium sulfate double salt at pH 2 5 Final purification of the pentammine liquor is effected by pH adjustment with ammonia and removal of divalent nickel by ion exchange Purified liquor is then advanced to hydrogen reduction to produce cobalt metal Although similar to other cobalt refining processes used in the nickel industry, the Port Nickel process is unique because of a single point chemistry adjustment for a number of unit operations that occur in succession.

Jan 1, 1981

By A. E. Worthington, R. F. Meldau

An analog computer study was made of the reduction of the magnitude of the SP by formation geometry and resistivity effects. Practical field .situations were studied. The analog data were converted to the form of departure charts. These charts may he used to determine the reduction in the SP due to the above eflects pith good precision Quantitative interpretation of the SP log in terms of formation water resistivity is presently based on the premise that the observed SP is equal to the electrochemical potential developed across a shale between the mud filtrate and the formation water. This procedure inherently assumes that, first, no electro kinetic (streaming) potential is present, and, second, that the SP is not reduced by resistivity or geometry effects in the formation. When, however, such a reduction of the observed SP does occur, one may write, SP = b,E, b, E, (1) where SP is the observed self-potential opposite the center of the bed under consideration. In this case, E, is the electrochemical potential, E, is the electrokinetic potential, b, is the electrochemical reduction factor, and h, is the electrokinetic reduction factor. The first assumption above is equivalent to assuming E, = O in Eq. 1 and the second assumption is equivalent to h, = b, = 1. Examination of electric logs shows that for many formations of interest the observed SP is reduced below its maximum value. The object of this work is to aid quantitative SP interpretation in at least some of these situations by obtaining values for b, and b, in Eq. 1 as functions of realistic combinations of bed thickness, depth of invasion, and formation resistivity. The only previously published work in this field known to the authors is by H. G. Doll' in 1948. He evaluated b, under conditions permitting exact analytical solution. His work clearly established the importance and qualitative nature of formation geometry and resistivity effects upon the SP, but the necessity of obtaining analytical solutions restricted his study to situations of limited practical interest. In order to extend such studies to practical combinations of formation parameters which do not lend themselves to feasible analytical solutions, the results reported in this paper were obtained by use of a special analog computer. THE ANALOG MODEL The analog model used for this study was the Guyed Analog Computer which originally was designed and built for resistivity log departure curve studies. It consists of a two-dimensional mesh of resistors, with the vertical mesh corresponding linearly to vertical distance along the borehole, and the horizontal mesh corresponding to radial distance from the borehole axis. By proper choice of horizontal resistor values, a three-dimensional, axially symmetric, borehole-formation problem can be modeled with this two-dimensional array. These and other details of the model are contained in a paper by H. Guyod'. The geometry used for the SP studies with the analog is depicted in Fig. 1. This configuration has a horizontal plane of symmetry, and, hence, the model, and the following discussion, need only to be concerned with one quadrant such as shown in Fig. 2. A further simplification arises by considering that both the natural potential sources and those used in the model have fixed internal impedance. Therefore, the current flows produced by these sources can be separated and studied independently ( i.e., the superposition theorem can be applied). SP = SP, i SP, = h,E, + b,E, ,(7)

By J. V. Richards

The Altar district, State of Sonora, Mexico, is for the most part a desert with but little rain-fall and few running streams. On account of this scarcity of water it is necessary for the natives to " dry-wash" the placer-gravel, and the object of the present gaper is to describe some of the more commoil Mexican dry-mashing devices. My observations were confined to a property known as Las Palomas placers, 15 miles from the Gulf of California and about 150 miles south of the United States border; a brief description of which property may be of interest as illustrating what is, perhaps, a typical Sonora dry placer. It is said that as long as a century ago the Yaqui Indians discovered rich cement-gravel, known as argo masa, at Las Palomas, and that there has been a more or less steady production of gold from the property ever since. The argo masa, is a fairly-coarse gravel, the pebbles being quite firmly held together with a lime cement. Gold is scattered through this cement in particles ranging from fine specks to pieces several grams in weight, and occasional large nuggets are encountered. The contents vary so widely that it is difficult to estimate the average value, but returns of from $10 to $50 per cubic yard are common, and it is doubtful if the Indians considered anything less than from $4 to $5 a yard as "pay dirt.'' This ar-90 masa, occurs in channels varying in thickness from a few inches to several feet, and in width up to 300 ft. These channels are continuous and are probably ancient stream-beds. They are for the most part covered with an over-burden of a more recent gravel, varying from 30 to 50 ft. thick, and the fact that this over-burden contains values as high as $1.50 per cubic yard, and yet was not worked by the Indians, shows that their idea of what constituted mas high.

Jan 1, 1911

By Eugene Guccione

For at least a decade, the energy crisis was accurately predicted by a small number of industry people who were ignored until last year, when they suddenly found themselves accused for their "lack of planning" and "greed." With the worsening shortage of natural gas and oil, the current scramble is for alternate energy sources-which means: a big rush into coal and uranium mining. (Some big plans are also on the drawing boards regarding geothermal steam, oil shale, tar sands, and even solar energy. But developing such new industries from scratch would be difficult enough even in a healthy economic climate-which is not exactly what the country currently enjoys.)

Jan 8, 1974

By Grant Buma

The purpose of this paper is to present arguments and evidence that there are natural processes at work which tend to minimize the impact of solution mining on the environment. The contaminants have two sources. First are elements which were present in the roll-front deposit in insoluble compounds, for example, uranium in uraninite and coffinite, molybdenum, arsenic, iron, cobalt, nickel, etc. in sulfide minerals, vanadium in micas and clays, etc. Second are elements introduced by the leach liquor. Precipitation of reduced compounds, scavenging of heavy elements and absorption by quartz and clays, can all reduce the amount of heavy elements in solution. If a roll can be demonstrated to be actively precipitating uranium and heavy metal elements, then the presence of precipitants (pyrite and carbon) can be assumed. Criteria for recognizing an active roll are described.

Jan 1, 1979

Jan 1, 1920

By L. H. Marshall

MALLEABLE-IRON castings frequently are made brittle by hot-dip galvanizing. The castings may be and usually are perfectly normal before the hot-dip treatment, in that they will stand a remarkable amount of distortion and punishment before fracturing, yet, after galvanizing, a single blow with a hammer will often cause a break. One such casting broke when accidentally dropped on a concrete floor. Such weakness causes galvanizers to view malleable cast iron with misgivings, and, in turn, is a source of worry to the manufacturer of the castings. It is felt, therefore, that a practical method of overcoming this embrittlement, a method that has already been used on several thousand tons of castings, will be of general interest. The purpose of this paper is to describe this immunizing process. DEVELOPMENT OF THE PROBLEM In the early days the trade was not much concerned with the finish of the castings and in most cases the only protection given to the parts placed in service was a coat of paint. It was soon found that this form of protection was inadequate and the user demanded a better type of rustproofing. In compliance with this demand, the use of zinc for coating gradually spread until it became general practice. More than half of all the zinc produced today is used for coating iron and steel, and, in spite of the recent use of cadmium and chromium, zinc coatings are still recognized as among the best general rust inhibitors for atmospheric exposure.

Jan 2, 1926

By Louis Katona

The practical execution of the design for rolling-mills presented by the writer at the Paris meeting* of thc Iron and Steel Institute in 1900 involves the determination of some questions not yet discussed, among which is the determinatioir of the amount of power required to perform the rolling of pieces of iron and steel of given dimensions. It is necessary to know this factor if we would put motors of proper capacity to the respective pairs of rolls, or, rcciprocally, if, having standard motors at our disposal, we would design grooves to suit them. Moreover, this factor is involved in giving right dimensions to every part of the rolls and housings. Expert designers of engines for driving rolling-mills of the present type receive very indefinite directions, such as: that the motor is to drive a light, medium or heavy train; that it must work with fly-wheel or reversing gear; that the number of revolutions per minute should not exceed 40 or 60, and that at a given speed the power developed should be from 100 to 200 H. P., or from 1,000 to 2,500 13. P. It frequently happens, however, that an cngine of 200 H. P. is forced under the circumstances to press or develop as much as 300 H. P., while, on the other hand, the ,1,500-11. P. engine may be rolling-stock which could be worked with a maximum expenditure of 60 to 80 H. P. Of course such variatior~s as these do not permit the best adjustment of parts or the best economy of power and fuel. The design of roll-trains is even more vaguely limited. Every part of a train, from the point where it connects with the engine to the last groove in the rolls, bears evidence that there are no rules for calculating even approximately the dimensions of the main-shafts, couplings, pinions, gears, rolls, trunnions,

Jan 1, 1904

By Donald E. Cummings

Measures appropriate for the control of the silicosis hazard in mining cannot be formulated precisely, but sufficient knowledge1-l9 has accumulated during the past quarter century to permit the suggestion of useful, though partly empirical, rules for its alleviation. The industrial hygienist today recognizes that the peril incurred by the inhalation of harmful dust is a function of two variable factors—the degree of harmful exposure and the specific susceptibility of the exposed individual to pulmonary injury. Control of the danger arising out of prolonged contact with pernicious airborne particulate matter is consequently best exercised by influencing both of these recognized variables. Obviously the problem has two broad aspects—one, medical; the other within the province of the engineer. I—Factors Comprising Degree of Individual Susceptibility Thorough investigations conducted among miners who have labored for years in the presence of recognized silicosis hazards usually reveal an impressive difference in the injury incurred by men whose exposure to dust has been nearly identical. After a quarter century underground, one individual is short of breath and incapacitated with miners' complaint, while a fellow workman suffers no pulmonary embarrassment and is in good health. Physicians ascribe this oft-observed difference in reaction to individual susceptibility and express a universal regret when they deplore the fate that chose to make the predisposed youth a miner rather than a farmer. To trust the health of miners to fate at the present time is even more unfortunate, because many of the factors that influence man's susceptibility to dust are known, and can be accurately determined by competent medical methods. Among the most important factors comprising susceptibility to injury by dust are the anatomical peculiarities of the individual's respiratory mechanism, his physiological response to the inhalation of dust, his previous dust, exposure, the existence of pulmonary infections or other pathological processes in his lungs, his age,

Jan 1, 1940

By Donald E. Cummings

Measures appropriate for the control of the silicosis hazard in mining cannot be formulated precisely, but sufficient knowledge1-l9 has accumulated during the past quarter century to permit the suggestion of useful, though partly empirical, rules for its alleviation. The industrial hygienist today recognizes that the peril incurred by the inhalation of harmful dust is a function of two variable factors—the degree of harmful exposure and the specific susceptibility of the exposed individual to pulmonary injury. Control of the danger arising out of prolonged contact with pernicious airborne particulate matter is consequently best exercised by influencing both of these recognized variables. Obviously the problem has two broad aspects—one, medical; the other within the province of the engineer. I—Factors Comprising Degree of Individual Susceptibility Thorough investigations conducted among miners who have labored for years in the presence of recognized silicosis hazards usually reveal an impressive difference in the injury incurred by men whose exposure to dust has been nearly identical. After a quarter century underground, one individual is short of breath and incapacitated with miners' complaint, while a fellow workman suffers no pulmonary embarrassment and is in good health. Physicians ascribe this oft-observed difference in reaction to individual susceptibility and express a universal regret when they deplore the fate that chose to make the predisposed youth a miner rather than a farmer. To trust the health of miners to fate at the present time is even more unfortunate, because many of the factors that influence man's susceptibility to dust are known, and can be accurately determined by competent medical methods. Among the most important factors comprising susceptibility to injury by dust are the anatomical peculiarities of the individual's respiratory mechanism, his physiological response to the inhalation of dust, his previous dust, exposure, the existence of pulmonary infections or other pathological processes in his lungs, his age,

Jan 1, 1940

By O. C. Ralston

The use of copper sulfate for improving the flotation behavior of sphalerite is probably at least 15 years old. The original discovery of its activating influence is somewhat obscure. The story goes that in the mill at Mascot, Tenn., its favorable action was discovered by accident, early in 1914, as follows: The original laboratory test work on a sphalerite ore gave favorable flotation results, but after a mill had been built the flotation concentration of the ore was very unsatisfactory. In diagnosing the probable reasons, one fact pointed out was that the laboratory test machine had been constructed of bronze whereas the commercial machine allowed pulp to come in contact only with wood and iron. A plate of sheet copper was hung in the flotation machine and results immediately improved. At first fanciful explanations of electrolytic and electrostatic behavior were given credence, but when the copper plate was removed and a small amount of copper sulfate substituted in the pulp an even more favorable result was obtained. Toward the end of 1914 copper sulfate was also adopted in the acid flotation circuit of the Butte and Superior Copper Co. Just who is responsible for the original discovery the present writers do not know. It seems strange that in that era of flotation litigation this discovery was not patented. While for pragmatic purposes it [nay be sufficient to know that the mere addition of copper compounds to a flotation pulp is sufficient to activate the flotation of the sphalerite, for scientific purposes it is quite desirable to know more about how the action takes place. It is the purpose of this paper to present certain evidence dealing with the mechanism of the beneficial effect. The description of the effect as activation in contradistinction to depression is now common in both the English and German languages. It makes no assumptions as to whether the zinc sulfide surfaces have been filmed with copper compounds. In fact, the principal differences of opinion expressed in the literature deal with whether there is an actual formation of CuS (or even Cu2S) on the surface of the sphalerite. Activation of sphalerite takes place in alkaline, neutral or weakly acid solutions and whereas the present day flotation of sphalerite is usually in ah alkaline solution, the early use of copper sulfate was in a sulfate solution.

Jan 1, 1930

By Harry M. Conger

It is a pleasure for me to keynote this first Western Regional Minerals and Coal Conference here in the Black Hills of South Dakota. It is pleasing for two main reasons. First, Homestake Mining Company has been associated with the Black Hills since 1875 when gold was discovered following Custer's trek through the Hills during 1874. Second, the future mineral development of the Black Hills will depend, to a great extent, on minerals and metals covered in this conference. The metals and minerals that are featured in this conference have unique similarities--and important differences--and therefore, will be of great interest to all who are involved in our industry in this area of the country. Precious metals have always been, and likely will always be, subject to political influence; they are only partially affected by the demands of our industrial economy. Energy minerals, while more directly affected by industrial stimulus, are also politically sensitive. In this regard, the need for a minerals policy affecting the energy sphere has been made very clear to us in the last five years. More importantly, the lack of a national policy and purpose relating to our total future energy needs has severely affected the overall economy and security of this country. Very briefly today, I would like to outline for you my thoughts on the future of these most important minerals. I will start by a discussion of precious metals, primarily my favorite precious metal, gold. A brief history of gold will be helpful in setting a perspective for forecasting its future although it is difficult to give a brief description of a metal that has been prized by man for over 6,000 years. Until recently, as you know, gold was held by the Federal government as a metal to be owned by the government only and

Jan 1, 1983

By Kalanadh V. S. Sastry, D. W. Fuerstenau

Design and operation of a batch balling drum that can be used easily for experimental investigation of the balling or granulation behavior of particulate materials are described briefly. An experimental procedure for ascertaining the growth kinetics of iron ore concentrates or other particulate materials with this kind of apparatus is outlined.

Jan 1, 1972

By A. E. Back, K. E. Tame, W. F. Wyman, S. F. Ravitz

IN 1940, when it appeared that the United States soon might be cut off from foreign sources of high-grade manganese ore, the Bureau of Mines began an extensive series of investigations on the production of ferrgrade products from low-grade domestic ores by ore-dressing, pyrometallurgical, and hydrometallurgical methods. Among the hydrometallurgical processes for oxide ores investigated was a sulphur dioxide process in which the manganese was recovered from solution by precipitation with lime;1 this process is essentially as follows: The ground ore is suspended in water and leached with SO2 gas to extract the manganese as manganese sulphate. Calcium chloride is then added to the slurry to precipitate calcium sulphate and form manganous chloride solution, and the resultant slurry is filtered to remove the calcium sulphate together with the in- soluble portion of the ore. Calcium hydroxide is added to the filtrate and the mixture is agitated with air to precipitate hydrated oxides of manganese and regenerate calcium chloride. The precipitate is calcined, and the calcium chloride is recycled. To determine manganese extraction, reagent consumption, grade of product, and similar data for this process, a laboratory investigation was started. Two minor modifications in the process were soon made: (I) the ore was suspended in calcium chloride solution instead of in water in order to extract the manganese and precipitate the calcium sulphate in one step, and (2) the agitation with air after the addition of slaked lime to the filtrate was omitted because manganese hydroxide is readily precipitated without air agitation and can be nodulized or sintered to a satisfactory product. When the process was carried through a series of cyclic tests, it was noted that the concentration of dithionate ion (which is one of the products of oxidation of SO2 by MnOz) in the cycled solution gradually increased; at the same time the chloride content of the solution gradually decreased, owing to soluble losses in the leach residue and in the precipitate. After a number of cycles, the calcium chloride became virtually completely replaced by calcium dithionate, the quantity of dithionate ion formed during the leach being more than enough to make up for the losses of dithionate in filtering. The calcium chloride process thus developed into a calcium dithionate process. Since the latter eliminated the need for make-up calcium chloride, and the dithionate solutions appeared much less corrosive than the chloride solutions, work on the calcium chloride process was dropped in favor of the calcium dithionate process. ACKNOWLEDGMENTS The dithionate process was developed by the Bureau of Mines as part of a

Jan 1, 1946

By C. M. St. John

INTRODUCTION The stress redistribution accompanying the excavation of a deep tunnel may induce failure of the rock. The role of the support system is to control the extent of the failed region and hence to limit closure of the tunnel within an allowable amount. In such circumstances, the design of the support system is generally based on the Ground Reaction Curve (GRC). The GRC is the relationship between the support pressure and the induced displacement at the tunnel wall for a circular tunnel under hydrostatic loading. In the calculation of the GRC (see Brown et al. (1983) for an exhaustive list of reference), the rock is generally treated as an elastoplastic material characterized by cohesive-frictional yield strength and by dilatancy during plastic deformation. A recent analytical development (Detournay, 1983) has allowed the generalization of the GRC concept for some cases of non-hydrostatic in-situ stress fields (Detournay and Fairhurst, 1982). As an application of that development, this paper describes design charts that provide powerful means of performing parametric analysis for tunnels subject to non-hydrostatic loading. BACKGROUND The in-situ stress in a plane perpendicular to the tunnel axis can be decomposed into mean and deviatoric components, Po and So (see Fig. 1). Since it is assumed that the rock is characterized by a Mohr-Coulomb yield strength, the deviatoric invariant So must be less than the limiting value Sl0 given by

Jan 1, 1984

By Orson Cutler Shepard, Charles F. Skinner

THE leaching method that was first widely used with the cyanide process consisted of percolation leaching of crushed ore in vats or leaching tanks. It was frequently necessary to separate the sand for cyanide treatment and discard the slimes, because only granular material allows the necessary amount of solution to percolate through it in a reasonable time. Later a slime process consisting of agitation followed by thickening and filtration was developed, and is extensively used to the present day. Even though the agitation-leaching slime process is considered satisfactory, the cost of plant and of operation are both greater than for a percolation-leaching plant of equal capacity. This situation has been recognized in the hydrometallurgical treatment of copper-bearing slimes; and a considerable amount of work has been done at the Southwest Experiment Station of the U. S. Bureau of Mines in an effort to develop a percolation method of treating slimes. Experimental work on the copper-leaching problem was started by H. E. Keyes1, and later tests were made by J. D. Sullivan and A. P. Towne2. The Bureau of Mines work resulted in the development of a process by which slimes were moisture-agglomerated with sand and crushed ore, to form a permeable mass through which solution could be trickled without breaking down the glomerules. The agglomeration trickle-leaching method was developed on a small scale and finally tried out in a 12-ton vat. Successful results were obtained as long as the leach solution was added slowly, so that the agglomerated charge was never flooded. If the leach solution flooded the charge, the glomerules broke down and the charge became impervious. There are two important difficulties in the application of the agglomeration trickle-leaching method to the cyanide process for gold and silver ores:

Jan 1, 1937

By J. D. Edwards, C. S. Taylor, A. S. Russell

Solubilities and densities are reported for alumina hydrates in NaOH solutions under the conditions of the Bayer process employed to purify alumina for aluminum production. The equilibrium constants for reactions to form A102- accurately correlate the effects of NaOH concentration on the solubilities; the temperature coefficients of the equilibria lead to heats of solution of 7.34, 4.76, and 5.24 kcal for the a trihydrate, a monohydrate, and ß trihydrate, respectively. Moderate calcination does not change the solubility of the a trihydrate but increases that of the a monohydrate. At solution temperatures above 100°C, the trihydrates transform rapidly to a monohydrate. Hydro-thermally produced a monohydrate is the stable phase above 20°C. CORNERSTONE of the aluminum industry, the Bayer process for alumina production is based on the difference in solubility of hydrated alumina in NaOH solutions between 170" and 40°C. Solubilities and densities in this system were determined thirty years ago by M. Tosterudl under the direction of J. D. Edwards and C. S. Taylor. The solubility data, which still appear more concordant than those in the literature, are employed to sort out the complex equilibria in this system. The nomenclature for the alumina hydrates is that presented in The Aluminum Industry' and more recently summarized in Alumina Properties.3 a trihydrate is the purified phase analogous to gibbsite, a monohydrate is similarly akin to boehmite, and ß trihydrate is sometimes known as bayerite. Literature Goudriaan4 reviewed the early literature on alumina in NaOH solutions and presented data on the solubility at 30°C of several forms. The gel precipitated from aluminum sulphate or chloride with ammonia and dried at 130" to 140°C had the highest solubility but was unstable, its solubility being cut to one-tenth on standing in NaOH. The solubility of the gel was decreased one-third on calcination at 300" to 400°C, while that of the gel transformed in NaOH at room temperature to a crystalline trihydrate was unchanged on calcination. The preparation produced by slow hydrolysis of sodium aluminate solution with CO, in the air gave solubilities in rough agreement with later values for a trihydrate. The solubility of this form was increased slightly by the calcination. Fricke and Jucaitis5 extended the work to 30" and 60°C with a trihydrate. They also gave solubilities for ß trihydrate (bayerite b), although the residue belonging to the left branch of the solubility curve corresponded to a trihydrate. The residues at high NaOH concentrations were mono and trisodium aluminates, the latter being 3Na2O . AL2O3 • 6H2O. Solubilities of a trihydrate at 95°C and of a monohydrate at 150" and 200 °C come from the work of Magarchak.6 a trihydrate transformed to a monohydrate above 95°C. A few measurements on the solubility at 25°C of an alumina trihydrate prepared by slow hydrolysis of NaAIO, solutions were presented by Sprauer and pearce.? Their analyses showed the monosodium aluminate to have the composition Na2O.Al2O3-2.5H2O.

Jan 1, 1956

By Edgar S. Cook

Portions of this paper repeat in substance the statements made by me in an address before the meeting of the American Society for Testing Materials, held in June, 1903, at Delaware Water Gap, Pa. The views I then expressed, I still hold and believe to be pertinent to the present discussion of this subject. In doing my part, therefore, at the request of our Secretary, towards the further consideration by the Institute of the Physics of Cast-lron from a commercial as well as a theoretical standpoint,—a theme which received interesting treatment in our meeting some years ago, but has been somewhat neglected recently,—I make no apology for reiterating the views I have expressed elsewhere. Indications all point to the substitution of classifying pig-iron by chemical analysis for the old-time method of grading by fracture. Commencing with the larger users, and the makers of specialties, who require more positive information as to the composition than is afforded by the fracture; the use of pig-iron, guided by analysis, has spread with much greater rapidity to all classes of foundry-work than the most sanguine expected. Grading by fracture, as guided by experience with any particular brand of iron, has some points in its favor. The fact that, for so many years, castings of multitudinous forms, and for an endless variety of uses, were made in a fairly satisfactory

Jan 1, 1905