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By Walter P. Jenkey

[ ] I. THE REDUCING ACTION OF CARBON AND OF HYDROCARBONS. Carbon has long been recognized as one of the most powerful reducing agents in the deposition of ores. Investigations, made by myself, of the zinc- and lead-deposits in Southwest Missouri, in the region centering about Joplin, where the formation of the metallic sulphides has been due to the action of bitumen, carbonaceous shales and bituminous coal, Lace afforded abundant evidence that the solid oxygenated hydrocarbons, particularly, when in fine powder and in suspension in the waters circulating through the ore-bodies, are the most energetic and powerful reducing agents known. Bitumen, liberated by the decomposition of the ore-bearing limestone, is found in the Joplin mines in all degrees of fluidity and hardness, dependent on the amount of oxidation it has undergone. From semi-fluid maltha it grades into partly oxidized mineral-pitch, which, by further oxidation, changes to hard asphalt, finally breaking up, from continued absorption of oxygen, into a fine powder resembling in appearance powdered coal. In this condition oxidized bitumen, from its light gravity, is transported readily in suspension in the underground circulating-waters. Bituminous coal and black carbonaceous clays and shales occur as surface formations, often in intimate association with

Jan 1, 1913

By J. Jones-Parra

In previous Technical Notes, W. R. Rose' and W. Purcell have discussed the capillary pressure data presented by Welge.' Welge obtained capillary pressure curves of the imbibition type in which it was necessary to apply to the apparent wetting phase a greater pressure than that of the non-wetting phase to complete the cycle and reduce the non-wetting phase saturation to low values. Rose suggests in his Note that conditions of equilibrium could not have prevailed, since the. non-wetting phase pressure must always be the greater. Pur-cell in his Note, proceeds to postulate a pore system consisting. of a series of "holes in a doughnut," in which he contends that under equilibrium conditions it is necessary to resort to negative capillary pressures before significant wetting phase displacement can take place. There is a remarkable similarity between the shape of the capillary pressure curve calculated by Purcell and those measured by Welge. It is the purpose of this Note to show that, because Purcell neglected to account for the behavior of the residual wetting phase saturation, his system was not in equilibrium during imbibition; and, furthermore, that if his system had been in equilibrium, negative capillary pressures would not have been possible. In Purcell's pore system, the residual wetting phase will form pendular rings at the interstitial spaces existing somewhere within the system, for example, such as those spaces between "doughnuts" as shown in Fig. 1. The true capillary pressure is that across the pendular ring interface, and for the system to be in equilibrium the pressure drop across all interfaces must be the same, including that across the interface in the tight pores A of diaphragm B (Fig. 1). As the pressure across the cell is reduced, the advancing interface will move into the pore from the diaphragm, but at each pressure, the curvature of the pendular rings must be the same as that of the advancing interface if equilibrium is to prevail. Since equilibrium conditions are the basis for the entire argument, it follows that pendular rings must grow as wetting phase enters the pore, that is, as the pressure across the cell is lowered. In Purcell's calculated curve, the residual wetting phase saturation remains constant as the capillary pressure decreases. Thus, his curve does not represent an equilibrium process.

Jan 1, 1953

By J. F. Nester, J. B. Schroeder

COMPOUNDS of rare-earth and iron-group elements are of technical interest because of their unusual magnetic properties. To date, however, all magnetic measurements1-4 have been made with polycrystalline, often polyphase, samples. For the measurement of anisotropic properties, single-crystal samples are necessary to avoid the averaging effect of randomly oriented grains. The purpose of this note is to describe a technique with which we have grown relatively large single crystals of YCo5, NdCo5, DyCo5, and "YFe9". Crystal growth of these materials is complicated because: 1) the binary equilibrium diagrams are, in general, not well-established; 2) in those cases where phase-equilibrium data are available, the compounds of interest are generally formed by peritectic reaction; 3) the molten component metals are chemically very reactive, making contaminaticn of the melts by the crucible material a serious problem. Techniques such as arc or levitation melting followed by strain annealing have been tried5)' in the past with these materials, but with little success because of the peritectic reactions and the inherently poor process control. For this reason we chose to use the zone-melting technique of Mason and cook7 for our work, since past workers8 have had some success in preparing single crystals of peritectic compounds by this method.

Jan 1, 1965

By L. W. Eastwood

THE structure of eutectics has been studied by a number of investi-gators, and the complexity of the structural relationship of the compo-nents has been agreed upon, especially that of the "eutectic colony," type III of Portevin's1 classification. This paper does not attempt to alter the present classifications of eutectics; rather, it discusses the relationship between the macrostructure and the microstructure of the copper-cuprous oxide eutectic, and describes in detail the mechanism of the formation and the structure of the eutectic. Further, throughout the entire discussion it attempts to point out certain misconceptions in regard to the interpretation of the observed structure of the copper-cuprous oxide eutectic, one of the so-called "eutectic colony" types, and to correlate as much as possible the work done by the writer with that done by other investigators. Of the three types of eutectics listed by Portevin,2 the eutectic colony type has presented the greatest difficulty in interpretation. Although the copper-cuprous oxide eutectic is typical of the eutectic colony type in appearance, it may not be truly representative because the copper forms about 96 percent of the eutectic and the cuprous oxide about 4 per cent. The interpretation of the origin and structure of the "eutectic colony" given here is strictly limited, therefore, to the copper-cuprous oxide eutectic.

Jan 1, 1933

By A. L. Holley

The three principal mines from which the celebrated Salisbury iron ores are obtained are called respectively the "Old Hill," "Davis," and "Chatfield" ore beds, and are situated in the town of Salisbury, Litchfield County, Conn., on the eastern slope of the Tocconuc range of hills.* The Old Hill Ore Bed is a tract of land of 100 acres, originally granted by the General Court in October, 1731, to be laid out by Daniel Bissell of Windsor. It mas Boon after surveyed and located by Ezekiel Ashley and John Pell. The descendants of Ashley are still proprietors in the mine. The supply of ore has been very abundant, and for many years was easily obtained, but latterly the cost of raising has been greatly increased. Up to about 1840 the average yield was estimated to be about 4500 tons per annum. The production has gradually increased until the average yield at present is estimated at 15,000 tons annually. The largest production in any one ymr was about 20,000 tons. The proprietors of this mine were incorporated many years ago under the style of " The Salisbury Ore Bed Proprietors." The Davis Ore Bed, named after an early owner, was originally called Hendricks Ore Bed, and was owned before the organization of the town of Salisbury by Thomas Lamb, one of the first settlers

Jan 1, 1879

By Ta M. Li

Recent start-up of the Pinto Valley mine and mill is expected to add to domestic copper mine capacity by some 62,500 tpy. Owned and operated by Cities Service Co.'s Miami Operations, the complex lies approximately 5% miles west of Miami, Ariz. The estimated $100- million project, the largest single construction project ever undertaken by Cities Service, includes the Pinto Valley open pit mine, a 40,000-tpd concentrator, and a 10-mile slurry pipeline that will transport a 28% copper concentrate slurry to a new filter plant located in Miami. Concentrate will be treated nearby at Inspiration Consolidated Copper Co.'s new smelter complex. The current pit design contains reserves of approximately 350 million tons of ore averaging 0.44% Cu. Based on an initial production target of 40,000 tpd ore and 60,000 tpd waste, mine life is estimated at 24 years. The current stripping ratio is 1.5: 1, requiring the ultimate removal of more than 500 million tons of waste and leach-grade material.

Jan 6, 1975

By R. P. Rothwell

Instruction by correspondence is certainly one of the most important and useful of modern educational methods. The paper on the " Scranton International Schools," by Prof. Stoek (Buffalo meeting, October, 1898),* gives an elaborate description of a single private enterprise in this direction, ignoring all others, and cannot be said to present a fair or impartial view of

Jan 1, 1900

By A. L. Holley

(Read at the Amenia Meeting, October, 1877.) THE three principal mines from which the celebrated Salisbury iron ores are obtained are called respectively the "Old Hill," "Davis," and "Chatfield" ore beds, and are situated in the town of Salisbury, Litchfield County, Conn., on the eastern slope of the Tocconuc range of hills.* The Old Hill Ore Bed is a tract of land of 100 acres, originally granted by the General Court in October, 1731, to be laid out by Daniel Bissell of Windsor. It was soon after surveyed and located by Ezekiel Ashley and John Pell. The descendants of Ashley are still proprietors in the mine. The supply of ore has been very abundant, and for many years was easily obtained, but latterly the cost of raising has been greatly increased. Up to about 1840 the average yield was estimated to be about 4500 tons per annum. The production has gradually increased until the average yield at pres¬ent is estimated at 15,000 tons annually. The largest production in any one year was about 20,000 tons. The proprietors of this mine were incorporated many years ago under the style of "The Salisbury Ore Bed Proprietors." The Davis Ore Bed, named after an early owner, was originally called Hendricks Ore Bed, and was owned before the organization of the town of Salisbury by Thomas Lamb, one of the first settlers *The data from which the historical portion of these notes has been compiled were collected by the Barnum-Richardson Company, of Lime Rock (Salisbury), Conn.

Jan 1, 1878

By C. B. Jordan

LAVES and Wallbaum' have described TiRu and TiOs as having the same structure as TiFe; they had previously described the latter compound as having the CsCl structure. On the other hand, a careful investigation of the structure of TiFe by Duwez and Taylor- ailed to reveal the ordered CsCl structure, finding instead a random arrangement of titanium and iron atoms on the points of a body-centered-cubic space lattice. Consequently, it is not clear whether Laves and Wallbaum proposed the ordered or the disordered structure for TiRu and TiOs. In order to settle this question as to the structural type and to obtain values of the lattice para- meters (thereby completely determining the structures), the present investigation was undertaken. Samples having the compositions TiRu and TiOs were weighed out accurately from iodide titanium supplied by the New Jersey Zinc Co., ruthenium powder from Goldsmith Brothers Smelting & Refining Co., and osmium powder from Wildberg Brothers Smelting & Refining Co. No analysis was made of any of these metals. According to the respective analyses of the suppliers, total impurities amount to less than 0.03 pct in the titanium and to less than 0.5 pct in the osmium. The purity of the ruthenium is not known. The alloys were prepared by arc melting in a furnace of the type described by Schramm, Gordon, and Kaufmann.9 pecimens for X-ray diffraction were obtained by crushing the ingots and passing the resulting powders through a 200 mesh screen. Diffraction patterns were made with a powder

Jan 1, 1956

By Richard L. Gordon

Minerals long have been important commodities in international trade. As an inevitable result, the governments of the world have employed a wide variety of programs that affect the flow of trade. Roughly speaking, we may distinguish between the desire of more developed countries (MDCs) like the United States, western Europe, and Japan to control imports of minerals and the concern of less developed countries (LDCs), like India, about exploiting and exporting their minerals. The terminology used to describe different countries and the classification of specific countries into groups is unsettled and often changing. The poorest countries have been characterized as backward, undeveloped, underdeveloped, and developing. The problem seems to be in selecting a term that is both accurate and polite. Less developed seems, for reasons outlined by Hagen [pp. 51-57], the most convenient term. The borderline between an LDC and an MDC is always open to dispute. Objective measures are difficult to develop because of deficiencies in basic data, and enormous conceptual problems arise in making valid comparisons from even good data [see Hagen, pp. 7-28]. Thus, policies of the MDCs can be evaluated chiefly by using a few basic arguments for protectionist attitudes towards international trade. In dealing with the LDCs, a more far-ranging evaluation that covers general economic policy goals, the role of foreign investment, and the indirect effects of trade is required. This duality breaks down when trying to deal with the depressed areas in an MDC; here the issues are more akin to those associated with problems in an LDC. Similarly, variants of arguments used in LDCs appear in debates about foreign investments in MDCs. The whole discussion of minerals in LDCs, moreover, has obvious implications for MDCs like Canada and Australia. They, too, must face problems about the best utilization of their resources. THE RESTRICTION OF MINERAL TRADE BY DEVELOPED COUNTRIES[a] At least to some extent, the world's leading industrial nations have intervened to control the inflow of minerals. Such regulation is particularly pronounced for energy. Both the United States and western Europe employ

Jan 1, 1976

By Vincent T. Ricca, Kurtis Chow

When dealing with acid mine drainage as to treatment levels, costs, and evaluation of abatement schemes, predictions of the quantity and quality of the discharges are needed. An acid mine-drainage model is presented in this paper. In essence, the model is a hybrid of computer programs for stream flow simulation and acid mine drainage. Two major aspects of the model are discussed: mine-water generation and acid-load production. The former is based on hydrologic concepts and the latter on pyrite oxidation kinetics and oxidation product removal. The total model is programmed for the high-speed digital computer. The major inputs are: climatological, basin characteristics, and mine characteristics data. By the use o f the hydrologic model the amount of water that flows through the pyritic system is determined. From this information, acid loads removed by leaching, inundation, and gravity diffusion are then predicted. The outputs from the total model are: average daily mine-water discharge, the associated acid concentration or load, plus the average daily flow in the receiving streams or at basin outlets. The capabilities of the separate models have been tested individually and the joint model has been applied to a small drift mine in southeastern Ohio.

Jan 1, 1975

By J. Ostachowicz, B. Holynska, M. Lankosz

The paper presents an analyzer and the method for the continuous determination of weight percentage of ore grains with diameter smaller than 75 µm in mineral slurries. The method is based upon the measurement of characteristic x-rays of copper excited by primary radiation of two different energies 16.5 keV and 60 keV from Pu238 and Am241 sources respectively. Additionally the backscattered primary radiation is measured in order to correct the variations of the solids content in the slurry. Since the particle size distribution of slurry can be described by the Rosin-Rammler formula, some calculations have been carried out in order to evaluate the influence of distribution parameters upon the results of the measurements of weight percentage U75 of particles smaller than 75 µm. The influence of solids content and of the copper concentration variation on the results has been also evaluated.1 It resulted from the calculations that the ratio rl/rz, where rl and r2 are the relative intensities of copper characteristic x-rays excited with 16.5 keV and 60 keV photons respectively does not depend on the copper content within the range 1 % to 4% of copper and is slightly dependent on the solids weight fraction and its chemical composition. The change of the dispersion parameter of the Rosin- Rammler distribution from 0.5 to 0.9 results in a change of value of U75 of approximately 3.0%. The results of calculations have been confirmed by the results of laboratory experiments. Therefore, a prototype of industrial analyzer for continuous determination of weight percentage of particles smaller than 75 µm has been designed and made. Its schematic drawing is shown in [Fig. 1]. Slurry is flowing down through steel flow-cell of the length equal to approx. 2 m. In the center, two XRF measuring heads (1) and (2) are located. Each of the heads comprises a rigid waterproof cover (3) with the mylar window (4), in which a proportional counter of resolution 15% for 6.4 keV is mounted with a preamplifier (5). The low- energy isotope source (6) is centrally located above the detector

Jan 1, 1980

TITANIUM is one of the most abundant elements in the minerals that make up the earth's crust but its use in industry is only a generation old; yet probably no other important commercial mineral raw material (except possibly magnesium) has undergone more changes and developments in sources of supply, in processing techniques, in uses and applications, in the past 10 years, or stands on' such a threshold of still more advances. Its outstanding use today is as the oxide, and because of its extreme whiteness, high refractive index, chemical stability, and relative cheapness, it has become the white pigment used in the largest volume. New developments in the uses of titanium metal, potential and actual, may surpass the pigment use of the oxide before many years. TITANIUM-BEARING MINERALS Although a number of minerals contain titanium as the principal metal, only a few are of commercial importance. These are arizonite, ilmenite, and rutile. The other oxides, brookite, pseudobrookite, and anatase, occur in a few deposits, one at least of minor importance. The silicate titanite, and the double oxide of calcium and titanium, perovskite, occur in a few deposits in quantities sufficient to be considered as potential ores were not richer deposits of the oxides available elsewhere. Arizonite is a name given by Palmer46a to a mineral found some years ago in minute quantities in Arizona, which has the formula Fe203.3Ti02. Unexpectedly, it was found that the black titaniferous iron oxide found in large quantities on the beaches of many continental land masses corresponds in chemical composition to this formula (although ferrous oxide is always present). No one has yet been able to prove that the commercial mineral on the beaches is truly arizonite, or an allotropic modification of it, since X-ray investigations by Howard Carl and A. F. Gabriel, of the U. S. Bureau of Mines, and by the X-ray laboratory of the Chemical Department at the Experimental Station of the du Pont company, have shown only that the sand mineral gives just a jumble of lines, rather than an identifiable pattern. Lack of a better name,

Jan 1, 1949

By P. Stark, B. S. Lement

ACCORDING to Hanemann1 the hardness of retained austenite in a 1.7 pct C steel is increased by subsequent tempering. He reported that the hardness of this constituent increases only slightly on tempering to 300°F, rises more rapidly above this temperature, and attains the same value as the tempered martensite present in steel at approximately 480°F. The variation of hardness of both retained austenite and martensite with tempering temperature as obtained by Hanemann1 is shown in Fig. 1. Hanemann attributes the increase in hardness of the retained austenite essentially to continued formation of fine needles of martensite on tempering. Although he did not explain the actual mechanism involved, work hardening of retained austenite by the plastic deformation associated with such martensite formation appeared to be a possibility. Recently Lement, Averbach, and Cohen2 reported the existence of subgrains, about l000Å in diameter, in retained austenite and suggested that they may be delineated by a subboundary carbide. This raised the possibility that carbide precipitation might be responsible for the hardening reported by Hanemann. In view of these conflicting possibilities, an investigation" was carried out on a high purity, Fe-C alloy containing 1.7 pct C in order to clarify the nature of the phenomenon involved in the reported hardening of retained austenite. This investigation involved correlation of changes in microhardness and microstructure of the austenite as a result of tempering. Microhardness tests were made with a Tukon tester using a 25 gram load and a Vickers diamond. It was found that two groups of austenite hardness values were obtained after tempering at a series of temperatures up to 450°F, which was the highest temperature at which retained austenite regions could be identified microscopically. One group represents a high hardness level which in-

Jan 1, 1955

The regular activities of the Institute are financed mainly by income derived from members' dues, from advertising in MINING AND METALLURGY, and from the sale of publications to the public. In addition, collateral activities and special projects are financed each year by means of income from endowed funds controlled and administered by the Institute. In the aggregate, the amount of these endowments totals more than $684,000. An active effort is being made to increase the endowment funds of the Institute through a standing committee, of which Henry Krumb is Chairman, and of which the other members are: George D. Barron, Cleveland E. Dodge, John V. N. Dorr, Howard N. Eavenson, D. %. Jack- ling, Harvey S. Mudd, Wallace E. Pratt, Milnor Roberts, and Wilfred Sykes. This committee believes that there exists a tremendous opportunity for the Institute to be of evergrowing service to the public, to the mineral industries, and to the profession. It welcomes suggestions as to names of men of means who are vitally interested in the mineral industries, and to whom the opportunity to make a contribution or bequest might appeal favorably if presented in the proper light.

Jan 1, 1946

By D. J. Bourne, G. E. Atwood

The new potash refinery of Duval Sulphur & Potash Co. produced its first tonnage of muriate of potash in November 1951. Full capacity was attained in early 1952. Excellent extraction efficiency is being obtained by the process, which is basically froth flotation. System temperature control is practiced and has proved to be of great metallurgical value through high potassium recovery and. low reagent cost. WHEN Duval Sulphur and Potash Co. recently entered the established potash industry, the vast amount of pioneer work essential in an entirely new endeavor was unnecessary. Thus it was possible to screen and assemble proved techniques into a highly efficient process based on the combined knowledge of the industry. It is hoped that the refinements Duval has added to these cumulative achievements will contribute to the rapid advance of the potash industry and related enterprises. The process selected utilizes as raw material syl-vinite ore typical of the Permian Basin. This ore is principally comprised of interlocked crystals of potassium chloride, about 40 pct, and sodium chloride. Also there is as much as 1 1/2 pct of dispersed clay slime which, because of its nature, highly complicates beneficiation of these ores. The refining method is basically flotation in which the mineral sylvite is floated away from the halite-clay gangue to produce a 60 pct K,O muriate of potash product for the plant-food trade. It departs from established practice in the use of an improved reagent scheme, developed by the company's technical staff, and in

Jan 1, 1954

By R. H. Jacoby, V. J. Berry

Future depletion performance and ultimate oil recovery from reservoirs producing under volumetric control are often predicted with the aid of a material balance equation. When the reservoir fluid is very volatile, however, certain assumptions implicit in the use of the conventional methods are no longer valid. This is became laboratory differential vaporization test procedures do not adequately represent the reservoir depletion process and the performance of surface separation facilities. In such cases recovery of stock tank oil per unit of pressure decline can be predicted only from a detailed knowledge of the separator conditions and the over-all composition of the fluid entering the wellbore at each stage of depletion. Surface recovery is not simply related to the total quantity of liquid flowing into the well under reservoir conditions. In order to improve predictions for reservoirs which produce volatile oils, a step wise method of calculation has been developed. This method uses relative permeability data and multicomponent flash calculations to predict oil and gas production as a function of reservoir pressure. Calculations are presented for a reservoir containing a volatile crude oil, and predicted tank oil recovery by primary depletion is more than twice that predicted by conventional methods which are known to be adequate for ordinary black crude oils. Calculated maximum produced gas-oil ratio is less than one-fourth of the conventional prediction. Wellstream compositions have also been used to determine variation in stock tank oil composition and liquid content of the separator gas. This information is of particular importance for crude stabilization calculations and for design of gasoline plant facilities to recover LPG and natural gasoline. INTRODUCTION The estimation of oil reserves and the prediction of future recovery performance of petroleum reservoirs is a frequent task of the petroleum engineer. If the reservoir produces under volumetric control, performance calculations for primary depletion are made by combining oil and gas material balances with the gas-oil flow characteristics of the reservoir rock. For black oil reservoirs, the Schilthuis1 type material balance is commonly employed. For gas or gas-condensate reservoirs, where only one phase is flowing under bottom-hole conditions, a more simplified material balance is used. In the period in which these material balance methods were conceived and put into practice, it was common to classify reservoirs according to the type of fluid produced as (1) black oil reservoirs, or (2) gas or gas-condensate reservoirs. Recently, however, deeper drilling and more extensive studies of reservoir fluid properties have led to the recognition of reservoir fluids with phase characteristics between those of ordinary black oils, and gases or gas-condensate fluids. These intermediate fluids contain relatively large amounts of the hydrocarbons ethane through decane and are found in deep, high temperature (250°F) reservoirs. Such fluids are often referred to as high shrinkage crudes or "volatile oils." They are usually characterized by tank oil gravities above 45° API. high solution gas/oil ratios,

Jan 1, 1958

By M. R. Pickus, C. H. Mathewson

THE study of the plastic deformation and recrystallization of metals has been the subject of many investigations. In regard to the simple deformational processes, such as tension and compression, the early knowledge gained from studies of polycrystalline material has been supplemented by many significant researches on the behavior of single crystals. Unfortunately, this has not been true for more complicated deformational processes. As far back as 1927, G. I. Taylor1 wrote: It is impossible in the present state of knowledge to do more than give a possible reason why (face-centcred cubic) crystals set themselves with a (110) direction in the plane of rolling, and at right angles to the direction of rolling. The explanation of why the orientation of the crystal axes round the transverse direction is what it is, must be left till the distortion of metals, and particularly single crystals of metals in the process of rolling, has been studied in greater detail. That this gap in the systematic study of deformation and recrystallization has not yet been filled was indicated by C. H. Samans,2 who wrote in 1934 that "only four investigations upon cold-rolled single crystals of any of the face-centered cubic metals have been reported in the literature." Of these four studies, only those of S. Tanaka3 and T. Sakao,4 both of whom worked with aluminum crystals, had quantitative significance. The other two, carried out by F. Wever5 and W. G. Burgers," were of a qualitative nature. It is our hope that the present investigation may contribute something to the knowledge necessary for a rationalization of the origin of rolling textures in terms of the known behavior of single crystals, and may add pertinent information concerning the recrystallization characteristics of deformed single crystals.

Jan 1, 1938

By Wallace W. Key

Chalk is a natural calcium carbonate occurring as the remains of soft, friable, minute marine organisms. Whiting can be either finely ground calcium carbonate prepared from chalk, marble, or limestone or the product obtained by chemical precipitation from a solution or suspension containing lime. Until relatively recently, whiting made from limestone was termed "whiting substitute," but it is now usually designated as limestone whiting. Precipitated calcium carbonate, sometimes called "precipitated whiting" or "precipitated chalk," is a finely divided calcium carbonate product obtained by chemical precipitation from a solution or suspension containing lime. Considerable quantities of precipitated calcium carbonates are produced from many chemical processes. Naturally occurring calcium carbonate in a variety of crystalline forms and in all degrees of chemical purity forms a substantial part of the earth's crust. Exactly where a chalk grades into a marl or calcareous shale through increase of clay or silt or into a hard limestone through consolidation and crystallization is difficult to determine because no rigid specifications have been promulgated for classifying them. Composition and Properties Once considered to be amorphous, chalk was later found to be cryptocrystalline. In the pure state it consists entirely of CaCO3, but many deposits are impure. When impurities are removed and the material is reduced to a finely divided state, it is known as chalk whiting. Much confusion attends the use of the term "chalk" as well as the classification of whiting materials. For instance, blackboard chalk is not necessarily chalk but is sometimes plaster of paris or a form of talc. Colored "chalks" may be true chalk colored and compressed with a binder but are probably such materials as hematite, clays, or carbonaceous matter. The term whiting was applied exclusively to the product derived from true chalk before World War I. Chalk imports were difficult to acquire during World War I, and whiting substitutes, a term applied to the products derived from natural rock deposits and precipitated calcium carbonate, were introduced. Substitute whitings were not acceptable at first, but it was found that blending true chalk with substitutes often created an improved product; eventually by selection of limestone and finer grinding, products not only acceptable, but for some uses superior to chalk whiting, were developed. Gradually the term "substitute" was dropped because chalk whiting had lost its importance, being largely supplanted in the United States by other whiting materials. Whiting is now made in ever-increasing quantities from limestone, marble, dolomite, marls, vein calcite, oyster-shell, as well as primary and byproduct precipitated calcium carbonates. Distribution of Chalk Europe-In England, France, Belgium, Denmark, and other European countries highpurity chalk occurs in extensive beds. The Cretaceous period, or the "age of chalk," in geologic history receives its name from the great deposits of chalk exposed on either side of the English Channel. It has been estimated that oceans in which chalk and allied deposits were formed covered more than 500,000 square

Jan 1, 1960

W. ROWLAND Cox,* New York, N. Y. (written discussion?).-The process described by Mr. Malcolmson undoubtedly represents a great stride toward conservation of our natural resources. Without discussing the subject from an economic standpoint, I wish further to emphasize the fundamental principles of the Smith process in order that its economic value may be fully appreciated. The process is essentially a means of producing an ideal fuel, as regards its combustion qualities, by the removal of the so-called volatile matter from the coal, in the form of byproducts, which have value for other purposes far in excess of their fuel value. In other words, coals which contain. large amounts of gas, tar, and ammonia, and are not suitable for domestic or industrial fuel, or for treatment in byproduct coke ovens or gas retorts; because they possess poor coking qualities, can he prepared for commercial use by the. Smith process with a very high degree of efficiency. Much work has been done along this line, both in this country and in Europe, in developing a means of preparing coal, as the economic advantages have long been recognized. To the best of my knowledge, the Smith process is the only one that has proved its commercial adaptability. Distillation of coal at 900° to 1000° F. (480° to 540° C.) yields a large amount of tar and oils. The residue of the distillation, however, is a very friable semi-coke, wholly unsuitable for use as a fuel, unless it can be charged directly into a byproduct gas producer. The problem which confronted the inventor was then to convert this carbon residue into a commercial product, and it is in this step that the Smith process has overcome the obstacles which prevented a number of other methods from becoming commercially practicable.

Jan 10, 1918