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Sykes, W. P.-Effect of Temperature, Deformation, Grain Size, and Rate of Loading on Mechanical Properties of Metals. Discussed by Zay Jeffries, W. H. Bassett, F. E. Carter 3 Evans, Geo. Watkin.-Alaskan Coal Fields. Discussed by P. N. Moore, H. H. Stoek, G. S. Rice, H. Emerson 4 Eavenson, Howard N.-Run-off and Mine Drainage. Discussed by J. R. Campbell, Andrew B. Crichton, J. B. Warriner, R. V. Norris, H. G. Moulton, H. B. Wright 7 Andrews, Allen, and Garcia, John A.-Skip Hoisting for Coal Mines. Discussed by R. V. Norris, Geo. S. Rice, H. N. Eavenson, E. A. Holbrook, Robert Obert, Andrews Allen, T. M. Chance 12 Rice, Geo. S.-Coal-pillar Drawing Methods in Europe. Discussed by Carl Scholz, D. Harrington; H. 1. Smith 16 Knapp, Arthur.-Modified Oil .well Depletion Curves. Discussed by Roswell H. Johnson 21 Alvey, Glenn H., and Alden W. Foster.-Barrel-day Values. Discussed by Roswell H. Johnson 22 Matteson, W. G.-Secondary Intrusive Origin of Gulf Coastal Plain Salt Domes. Discussed by Eugene Coste, E. W. Shaw, Joseph E. Pogue, F. G. Clapp, E. DeGoIyer, W. G. Matteson, H. W. Hixon, R. Van A. Mills 23 Reger, David B,-Carbon Ratio of Coals in West Virginia Oil Fields. Discussed by J. T. Singewald, Jr 33

Jan 5, 1921

By J. C. Fisher, J. H. Hollomon

The fundamental problem concerning the fracture of both crystalline and noncrystalline solids is the divergence between the actua1 and the theorcticallY computed fracture stresses; the stress required for fracture, computed from the forces between atoms, is many times that actually observed with commcrcinlly available materials. Computatiolls have been made,,2 indicating that the theoretical fracture stress should be from 100 to 1000 times that actually observed. There are other incidental problems that have arisen, perhaps the most importallt of which is the problem of size effect often observed in the measurement of the fracture stress of non-metallic solids, such as glass. Another effect conccrns the relation between deformation and the stress required for fracture, Experiments recently made with pearlitic steels indicate that the tensile fracture stress increases with increasing tensile deformation and decreases with increasing prior com-pressive deformation, This marked ani-sotropy of the effect of deformation on the fracture stress is in contrast with the essential isotropy of the flow stress. Early experiments on rock salt crystals by Joffe, et al.3 have illustrated the effect of tensile strain in increasing the tensile stress required for fracture. A consistent theory must be constructed that will explain not only the divergence, of the measured fracture stress from the theoretical value, the size effect, and the ergence of deformation; but will also explain and predict the effects of combined stress, of temperature, of strain rate, and of metallurgical structure. With respect to this last variable, it has now been relatively well established that the carbide particle is the clement of structure controlling the fracture of steels. In steels carbide particles vary in shape from plates to spheroids. It has been found that not only docs the magnitude Of the Fracture stress depend upon the size and shape of these particles. but also its dcpendencc upon strain is affected by changes in 'hap' an' size Or the particles. The precipitate resulting from the age hardening Of duralumin also modifies the fracture stress of this alloy. Nonmetallic inclusions greatly lower the fracture stress of all metals. The magnitude of the lowering depends 0' the size and shape of the included particles. In glass, the major source of the low fracture stress has been fairly conclusively demonstrate' by Griffith4 '0 arise from real flaws or cracks present in the material. He showed that the stress concentration at the end of a defect was of suficient magnitude to raise the stress at this location to a value comparable with the theoretical strength Of the material. If the cracks were reduced in size, Griffith showed that the observed fracture slrength the by virtue Of the decrease in stress concentration. He also pointed out that cracks disposed perpendicularly to the applied tensile stress would be more effective in lowering the fracture

Jan 1, 1947

By J. H. Hollomon, J. C. Fisher

The fundamental problem concerning the fracture of both crystalline and noncrystalline solids is the divergence between the actua1 and the theorcticallY computed fracture stresses; the stress required for fracture, computed from the forces between atoms, is many times that actually observed with commcrcinlly available materials. Computatiolls have been made,,2 indicating that the theoretical fracture stress should be from 100 to 1000 times that actually observed. There are other incidental problems that have arisen, perhaps the most importallt of which is the problem of size effect often observed in the measurement of the fracture stress of non-metallic solids, such as glass. Another effect conccrns the relation between deformation and the stress required for fracture, Experiments recently made with pearlitic steels indicate that the tensile fracture stress increases with increasing tensile deformation and decreases with increasing prior com-pressive deformation, This marked ani-sotropy of the effect of deformation on the fracture stress is in contrast with the essential isotropy of the flow stress. Early experiments on rock salt crystals by Joffe, et al.3 have illustrated the effect of tensile strain in increasing the tensile stress required for fracture. A consistent theory must be constructed that will explain not only the divergence, of the measured fracture stress from the theoretical value, the size effect, and the ergence of deformation; but will also explain and predict the effects of combined stress, of temperature, of strain rate, and of metallurgical structure. With respect to this last variable, it has now been relatively well established that the carbide particle is the clement of structure controlling the fracture of steels. In steels carbide particles vary in shape from plates to spheroids. It has been found that not only docs the magnitude Of the Fracture stress depend upon the size and shape of these particles. but also its dcpendencc upon strain is affected by changes in 'hap' an' size Or the particles. The precipitate resulting from the age hardening Of duralumin also modifies the fracture stress of this alloy. Nonmetallic inclusions greatly lower the fracture stress of all metals. The magnitude of the lowering depends 0' the size and shape of the included particles. In glass, the major source of the low fracture stress has been fairly conclusively demonstrate' by Griffith4 '0 arise from real flaws or cracks present in the material. He showed that the stress concentration at the end of a defect was of suficient magnitude to raise the stress at this location to a value comparable with the theoretical strength Of the material. If the cracks were reduced in size, Griffith showed that the observed fracture slrength the by virtue Of the decrease in stress concentration. He also pointed out that cracks disposed perpendicularly to the applied tensile stress would be more effective in lowering the fracture

Jan 1, 1947

By Donald H. McLaughlin

ALTHOUGH Cerro de Pasco was well known since the early sixteen hundreds as one of the major silver districts of the Andes, its development on a modern scale did not occur until the first decade of the present century when a syndicate organized by James B. Haggin initiated the enterprise that eventually grew into the complex and widespread operations of the Cerro de Pasco Copper Corporation. Options on a few claims in Cerro de Pasco that had been brought to New York in 1900 came to the attention of A. W. McCune, a mining man from Salt Lake City, who took them to Haggin and soon succeeded in interesting that creative mining financier in the possibilities of the district. James MacFarlane, an engineer well known to both Haggin and McCune, was sent to Peru early in 1901 to make the initial examinations which promptly led to acquisition of a substantial group of claims in the heart of the mineralized area. A syndicate to which Haggin turned over his rights was organized on Feb. 26, 1902 to provide the necessary funds. The original members were J. B. Haggin, who retained a 34 per cent interest, Edward H. Clark (for Mrs. Phoebe Hearst, the widow of Haggin's old associate, George Hearst), H. McK. Twombly, H. C. Frick, D. O. Mills, and J.P. Morgan.

Jan 1, 1945

By J. G. Early, F. V. Lenel, G. S. Ansell

The isothermal shrinkage rates of copper-powder compacts were determined in the temperature range from 760o to 1060oC. The rates for compacts fabricated from a pure spherical copper powder were compared, on the one hand, with those fabricated from a spherical powder containing a dispersion of aluminum oxide in the copper matrix and, on the other hand, with those fabricated from a pure copper powder having irregularly shaped particles. The irregular copper-powder compacts shrank much faster than the spherical copper-powder compacts and these, in turn, shrank faster than dispersion -strengthened copper -powder compacts. The experiments were run under a small external load. By varying this load, the stress dependence of the isothermal shrinkage rate could be measured for compacts from spherical-copper powders. This stress dependence was found to be approximately proportional to the 4th (dispersion-strengthened alloys) or 4.5th (pure metals) power of the stress. It is concluded that the material-trans port mechanism is due to dislocation climb rather than to Herring-Naharro creep. In this investigation the isothermal shrinkage rates of compacts made of copper powder with an average particle size of 70 g in the temperature range from 780o to 1060°C were studied. The aim of the investigation was to determine the mechanism of material transport responsible for the shrinkage of these compacts. Since the phenomenon observed in this investigation was shrinkage of compacts at high temperatures, it will be necessary to consider all the material-transport mechanisms possible in sintering. It is unlikely that evaporation and condensation, surface diffusion, or even volume diffusion of vacancies, in which surfaces of small radius of curvature are vacancy sources and those of larger radius of curvature vacancy sinks, will materially contribute to a sintering process involving shrinkage, i.e., one in which the centers of adjacent particles move towards each other. The two principal mechanisms which were considered were the so-called Nabarro-Herring mechanism and a plastic deformation mechanism by dislocation movement. Both of these mechanisms were originally conceived to explain creep, i.e., the plastic deformation of metals at elevated temperatures under a constant applied stress. The shrinking of metal-powder compacts which was studied in this investigation can be readily treated as a creep process. This means that the shrinkage rates observed are considered as creep rates under the influence of an applied stress. It is true that the stresses in sintering experiments are generally not constant but decrease continually with time, but, by considering creep rates or shrinkage rates over a relatively short time interval, the small changes in stress during this time interval can generally be neglected. Nabarro-Herring microcreep is a high-temperature deformation mechanism which is caused by a diffusional flow of vacancies from boundaries under a tensile stress towards those under a compres-sive stress. Herring1 has shown that in this type of microcreep the strain rate e is proportional to the applied stress and follows an equation of the form ma, aexp(-Q/RT) [l| where <j is applied stress, Q is the activation energy for self-diffusion, R is the gas constant, and T is the absolute temperature This type of creep can explain the shrinkage of a porous compact. The surface of the pores are subjected to the tensile stress of surface tension, while the grain boundaries are under a compressive stress also due to surface tension. Vacancies diffuse from the pore surface through the lattice to the grain boundaries, where they are eliminated. In order to maintain vacancy equilibrium at the pore surface the vacancies leaving the region of the pore surface are replenished from the volume of the pore, which means that the pores shrink.

Jan 1, 1964

By R. D. Pehke, J. F. Elliott

The solubility of nitrogen in liquid pure iron has been measured as a function of pressure and temperature. Sieverts&apos; Law is obeyed at all pressures up to 1 atm and the temperature coefficient of solubility is 8 x 106 %/°C. The solubility of nitrogen in liquid iron alloys has been studied by the Sieverts&apos; method and by the sampling method. The solubility is decreased by Al, C, Co Cu, Ni, 0. Si atzd Sn, and it is increased by Cr, Cb, Mn, Mo, Ta, W, and V. Interaction coefficients eN, for the effect of these elements on nitrogen dissolved in liquid iron, are reported. 1 HE effect of nitrogen upon the properties of steel may be desirable or not, depending upon the composition, processing treatment, and the use of the product. To understand the behavior of nitrogen in the various steelmaking processes, it is necessary to have reliable fundamental data pertaining to the solubilities, rates of solution, and chemical reactions of nitrogen in steel, particularly in the liquid state. In an effort to extend our knowledge in these areas, an investigation of the thermodynamics and kinetics of the solubility of nitrogen in liquid iron alloys was undertaken. The thermodynamic aspects of the study are presented in this paper. The solubility of nitrogen in liquid pure iron has received the attention of several investigators whose results are summarized in Table I. Reasonable agreement among the more recent researches1-l8 is found for the solubility of approximately 0.044 wt pct at 1600°C and 1-atm pressure of N,, for the temperature coefficient of solubility being small but positive, and for adherence to Sieverts&apos; law for pressures up to 1 atm. The solubility of nitrogen in a number of binary liquid iron alloys has been studied: Fe-A1,3 Fe-As,16 Fe-C,3, 71 18, 19, 20 Fe-Cr ,5,7, 10, 11, 15 21 Fe-Co,&apos;4, &apos;6 Fe-Cu,&apos;6 Fe-Mn,10, 11, 18 Fe-Mo,13, 16 Fe-Ni,10, 11, 13, 15, 16 Fe-O,16, 17, l9 Fe-p,7 Fe-S,l6 Fe-Sb,16 Fe-Se,lg Fe-Si,4) 97 &apos;77 187 19>2° Fe-Sn,16 and Fe-v.51 &apos;3 A few ternary systems have been studied, most of which were reviewed by ~angenberg" who applied the methods suggested by WagnerPz3 Chipman,24 Darken and G~rry, and Morris and Buehl26 for predicting solubilities in multicomponent alloys. Langenberg22 and Humbert and Elliott15 compared the solubilities computed from simple binary alloy systems with experimental measurements of nitrogen solubilities in liquid iron containing two or more alloying elements. The interaction coefficients for nitrogen in

Jan 1, 1961

By T. A. Rickard

The writing that is effective is woven with a fine texture into an agreeable pattern; it is free from knots, loose threads, and stray fluff. The instrument that weaves this literary fabric, whether it produce a homely sock or a lordly tapestry, a simple story or a learned &apos;Itreatise, is a disciplined intelligence, as sure as a steel needle, as precise as a swift loom. The simile breaks down at this point, for the product of the pen is instinct with the human spirit and therefore transcends in beauty anything made by a mere machine. If words are to be woven into eloquent meaning, they must be well knit. Upon the relation of words to each other and of groups of words to other groups, known as phrases, clauses, and sentences, depends the success of writing as a means of trans¬mitting thought from man&apos; to man. To be understood beyond question, you should know not only what your words denote but how to build your sentences; you must not only choose your words aright but construct your sentences properly. A sentence is a combination of words that makes complete sense; it says something about something. &apos; A clause is a subordinate sentence or a sentence within a sentence. A phrase is a group of words without a predicate; it makes sense, but not complete sense. For example: I shall wait for a few minutes before I go home: The whole statement is a sentence; "I shall wait" and "before I go home" are clauses; "for a few minutes" is an adverbial phrase. The orderly arranging of words and of combinations of words is called `syntax&apos;; and from the original Greek form, ouvaeis (suntaxis), is derived the Greek name for an editor,

Jan 1, 1931

By W. P. Haynes

ESTIMATED United States crude-oil production during 1943 established a new annual peak of 1,500,000,000 barrels, a daily average of 4,118,000 barrels. This would be an increase of 315,000 barrels per day, or 8 per cent over 1942 and 7 per cent over 1941, the previous peak. During the first ten months of the year, production jumped from 3,782,000 barrels per day in January to 4,400,000 in October. Available data for the last two months of the year indicate a leveling off of this trend, with daily rates slightly above 4,400,000 barrels.

Jan 1, 1944

By Arthur L. Walker

In June, 1893, while I was with the Old Dominion Copper Co. at Globe, Ariz., I received an offer to take charge, as manager, of the Baltimore Electric? Refining Co. which had recently built a plant at Baltimore, Md., having a capacity of about 1200 tons of electrolytic copper per month, using the Hayden series system. This was a very large output, for in those days the plants were small and the art was in its infancy. At the beginning of 1893 there were 11 electrolytic refineries in the United States, most of them using the multiple system. The Hayden series system was used at Baltimore and Bridgeport and the Smith series system was in operation at the Electrolytic Copper Co. at Ansonia, COM., and at the Pennsylvania Salt Co. at Philadelphia. In the latter system the plates were placed in a horizontal position, but the operating difficulties were so numerous it was soon discarded. The total production of these 11 plants in 1892 was very small; I have not been able to discover reliable figures of production. There were about thirty electrolytic copper refineries in the world that year, according to Titus Ulke, and the entire production of these

Jan 1, 1932

By F. S. Crawford

IRON and copper are mined in the Lake Superior district. The iron mines of the district have the best safety record for that industry in the country as a whole, while the copper mines of the district rank second in two of the four years recorded (Table 1). In Utah copper comes mainly from open-pit mines, which enables that state to lead easily in safety. All of the Michigan production comes from deep under-ground workings. About 60 per cent of the iron miners in St. Louis County, Minnesota, are employed at open-pit mines; this favorably affects the combined open-pit and underground accident-frequency rate, as this county pro-vides most of the Minnesota-mined iron ore. In Michigan, however, there are few open-pit mines, the bulk of the production coming from underground mines, while all of the Wisconsin production, just across the state line from Michigan, is from underground mines. In spite of the fact that fewer mines in Michigan use the safer open-pit method, the iron-mining industry of that state maintained a consistently low record from 1931 to 1934; however, it was many points behind its nearest com petitor, Minnesota, with its much greater production from open-pit mines.

Jan 1, 1939

By Leonard Grimshaw

THE idea of bonding two dissimilar ferrous metals, and making use of both, is an old one. Tips have been brazed onto tool shanks for many years. The bonding of larger pieces to form whole bars and sheets has also been accomplished, but has received little attention in the technical literature, although a number of patents have been issued covering various methods for its accomplishment. There are three main motives behind the manufacture of composite steels. One is that the physical properties of one steel may supplement those of another; a useful, but at the same time, hard, brittle steel may be backed by a soft ductile one, or a stainless steel may be backed by a steel possessing greater strength. Another motive is direct lowering of cost; an expensive steel may be backed by a less expensive one, bringing down the cost of the piece as a whole. The third motive is an indirect lowering of cost, as when a useful steel is backed by a steel that is easier to machine, so that machining cost on a finished product is lowered considerably. Often more than one of these motives lead to a decision to use a com-posite steel.

Jan 1, 1936

By C. A. Heiland

MEASUREMENTS of gravity with gravimeters have come into increased use in this country and abroad in the past five years. Probably 100 to 125 gravimeter parties are working in the United States alone. In oil exploration, gravimeter methods have relegated the gravity pendulum definitely to second place, if not third, and now closely rival and possibly surpass the torsion balance in many applications. Gravimeters have lately been applied in mining, although it is doubtful whether they will ever replace electrical or magnetic methods in this work. Notwithstanding the widespread application of gravimeters, there has been no article covering the entire field in the domestic or foreign literature. The purpose of this paper is to meet the demand for com-prehensive engineering information on the subject. The working principles of a number of gravimeters will be, illustrated and treated in relation to the action of corresponding seismometers and astatization methods. The mathematical discussion of theory has been confined to the most necessary fundamentals and been given in as ele-mentary form as possible. A description of calibration methods con-stitutes the last part of the paper. The symbols shown at the top of page 2 will be used in equations throughout the paper.

Jan 1, 1939

By A. L. Mular

lnput energy-size modulus relation at small reduc-tion ratios is expressed by Et = (M, -Mt) k;. In some cases 13 is close to Schuhmann&apos;s distribution modulus a in value. Experimental results in conjunc-tion with the equation demonstrate the fact that energy input which produced fracture is not expended on unbroken starting material inside the mill at any time. Recently, schuhmann1 derived the Charles equation2 using the postulate that complex com-minution operations can be considered as a summa- tion of many comminution events. The fragments resulting from each event are assumed to follow the Gaudin-Schuhmamn distribution. In his derivation, Schuhmann implies that the size distribution of the total mass of a material is determined by the fraction of that mass actually subjected to comminution. Consider a feed to contain a volume, Vo, of uni- formly sized homogeneous material. After t seconds of grinding, let the volume of broken material be Vo - Vt where Vt is the volume of starting material not yet broken. The size distribution of the broken material is given by: where V is the cumulative volume less than size X, and k, is the size modulus of the broken material at time t. The distribution for the total volume at this

Jan 1, 1962

By William M. Shepard

The Tintic mining districts of central Utah com- prise one of the major silver-lead producing areas in the United States. Ore valued at nearly $450 million has been produced from these districts since the initial discoveries, in 1869, of veins cutting the Silver City monzonite stock. Subsequent production from the famous manto-type "ore runs", which characterize the Main Tintic district, was followed during the past 40 years by discovery of the blind orebodies of the East Tintic district, including the famous Tintic Standard mine and the most recent discovery, the Burgin mine, currently being brought to full production by Kennecott Copper. The occurrence of blind orebodies of exceptional size and grade in both the Main and East Tintic districts has made this area a field laboratory of major importance for the study of geochemical dispersion halos and alteration features associated with known ore, and has led to the discovery of additional concealed orebodies. The larger share of the basic data-gathering and interpretation has been done by members of the U.S. Geological Survey who have been studying the Tintic mining areas since before the turn of the century. These studies have been supplemented and expanded by the geological staffs of the local operating mining companies, by exploration geologists and by students.

Jan 4, 1966

By Samuel Taylor

IF I LIVE another fourteen months and am still con-nected with the coal industry, I shall then have com-pleted a half century with it. Since May, 1874, when .I first entered the bituminous workings as a miner, I think I have held almost every position connected with a mine except possibly that of mule driver, for which I was unfitted by reason of my religious upbringing. We are all agreed, at least I have not heard it contra-dicted, that there is serious over-production in the bituminous industry. This has come about in various ways and is easily explained. During the Fuel Admin-istration, I recall making an estimate of the possible output of the bituminous mines of the country provided they were given a full force of men and a full-car supply; my estimate was a little over a billion tons a year. A few months ago, the late Francis H. Peabody, of Chicago, made a practically identical estimate. If, however, both of these conditions should happen con-currently, there would very soon be no market for the coal, and many of the mines would close down. Even today, if 10 per cent. more cars were furnished, to the bituminous mines, market prices would drop very seriously.

Jan 4, 1923

By W. A. Vine

When a hole is made in a stressed solid, such as rock pierced by mine openings, equilibrium of the solid is destroyed. To restablish that equilibrium the stress condition in the rock surrounding the opening becomes rearranged. This rearrangement may or may not develop local stresses in the vicinity of the opening which exceed the elastic strength of the rock. Since stability of the opening depends, therefore, on the strength of the naturally occurring rock surrounding the opening, this rock is an engineering material of construction, and all rock affected by the associated opening or system of openings may be considered a structure. The term invert is chosen to describe the formation of the structure built from the inside, as it were, and a consequence of mining rather than an entity built for a purpose. By definition, an invert structure is formed when openings are made underground and is com- posed of that material on the solid side of a rock-air interface wherein the stress condition is affected by the associated opening or system of openings. The shape of an invert structure is never clearly defined; the skin of the structure may be mapped, and even described, but the boundary of the structure within the solid rock mass must be arbitrarily set.

Nov 1, 1955

By AIME AIME

ON Thursday, Oct. 9, oil men from far and wide gathered at Beaumont, Texas to participate in a three-day celebration of the fortieth anniversary of the completion of the famous Lucas gusher well at Spindletop field just south of Beaumont, and to pay tribute to Anthony F. Lucas, for whom the Lucas Medal of the A.I.M.E. is named. In the afternoon the gathered host drove to the site of the discovery well to dedicate a 58-ft. granite monu¬ment erected on the spot where the original derrick stood. Representatives of the A.I.M.E. took a prominent part in the dedication ceremonies, giving the two principal addresses of the afternoon&apos;s program. Everette DeGolyer, past President, paid a personal tribute to Capt. Lucas, as a pioneer producer, an engineer, and a friend and well wisher of all young engineers. He gave a splendid picture of the useful and full life of Capt. Lucas who always took a great interest in the activities of the Petroleum Division of the Institute, from its inception to the time of his death.

Jan 1, 1941

AT the Tulsa meeting of the A. P. I., the following reso-lutions, expressive of the policy of that organization, were among those adopted: RESOLVED, That we endorse the conclusion of the Federal Oil Conservation Board in its report of September, 1926, that the prevention of the waste of gas incident to the pro-duction of oil is of paramount importance in the conserva-tion and economical production of oil, and the president of the Institute is requested to appoint a committee of seven to devise and suggest to this board, or the executive com-mittee, such measures as will enable the industry, while continuing to meet the consumption requirements for pe-troleum and its products, to conserve in its natural state such reserves of petroleum as may not then be required for consumption. RESOLVED, That the president of the Institute appoint a committee of seven to formulate and recommend to this board or its executive committee, at the earliest practicable date, a program of legislation; Federal and State, to be advocated by the Institute giving sanction and effect to agreements by oil producers for the curtailment of produc-tion in pools where and during periods when there is over-production, having for their purpose the economical and orderly production of oil.

Jan 1, 1927

By Philip D. Wilson

SPEED is essentiaI in this war program and it is hard to keep up with developments. When the title of this paper was chosen, the contemplated magnesium production for which plants were then under construction was some 200,000 tons of metal per year or sixty times the 3350-ton production in prewar 1939. A few- days later an analysis of the President&apos;s 185,000-plane pro-gram, incendiary bomb schedules, and the additional requirements of the Army. Navy and Maritime Commission made it apparent that a much greater amount of magnesium must be provided in 1943. The new figures are huge but the censor will not per-mit their disclosure.

Jan 1, 1942

By Reynold Q. Shotts

Data are presented which show that fractions of varying densities-from the same coals are oxidized at different rates by nitric acid. From oxidation data, the approximate quantity of "bright" and "dull" components may be calculated. Definite relationships between oxidation rate and rank are shown for density fractions from at least two bituminous coals.

Jan 1, 1950