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By C. E. Feltner

In a recent note, Meleka and Hiarris1 have reported that the application of a constant strain rate Ad a superimposed cyclic stress to 99.99 pct polycrystal-line zinc at room temperature produced some marked effects in the resultant behavior. In their work, one end of the specimen was pulled in tension at a constant strain rate while the other end was subjected to a sinusoidally varying load (20 cps) of constant amplitude. For the slower strain rates and the larger superimposed cyclic loads, it was observed that the specimen could withstand strains prior to failure more than 100 pct greater than the fracture strains obtainable in simple unidirectional straining. This ductility effect was interpreted as being due to a cyclic stress enhanced thermal recovery process. It is the purpose of the present note to describe some related effects in 99.99 pct polycrystalline cadmium. Specimens were loaded in repeated tension at room temperature with a stress of sufficient magnitude to cause failure in about 1000 cycles and the accumulated strain was measured as a function of cycles and time. In addition, some specimens were subjected to a steady creep stress equal in magnitude to the peak value of the cyclic tensile stress. The resultant strain-cycle and strain-time curves for both types of test are shown in Fig. 1. It should be noted that the static creep specimen failed in about one third the time required to produce a cyclic failure but in the cyclic test the specimen was able to withstand a uniform strain before necking more than 50 pct greater than that possible

Jan 1, 1963

By J. V. Emmons

THE processes of hardening and tempering steel tools within the past 15 or 20 years have been so developed that the forward strides of the industry can scarcely be followed by the average observer. No small part of the credit for this phenomenal advancement is due to the improved methods of measuring the high temperatures necessary. Pyrometry has made possible the discovery and use of the many special alloy steels the wonderful properties of which are revolutionizing the industrial world. So sensitive are these steels to changes of temperature that often a variation of only 10° F. at a critical point of the heat treatment will cause the failure of the tool. In the tool-manufacturing industry today, accurate control of the many heating operations is imperative. The principal processes in the manufacture of tools that require accurate high-temperature measurements are annealing, carburizing, hardening, tempering, and laboratory research. Several other operations, such as forging and straightening, use rougher and correspondingly less accurate methods. These operations are usually performed in the following approximate ranges of temperature: DEGREES F. DEGREES F. Annealing 1000 to 1700 Tempering 200 to 1200 Carburizing 1400 to 1000 Forging 1400 to 1800 Hardening 1400 to 2500 Straightening 300 to 1300 Laboratory research covers the entire range. Annealing and carburizing are usually done in muffle or semi-muffle furnaces, heated with coal, coke, oil, gas, or electricity. Many of them are of large size, holding several tons of steel at one charge. Both indicating and recording pyrometers are used. The recording instruments are generally of the thermoelectric type, while for the indicating, both optical and thermoelectric are used.

Jan 9, 1919

By A. E. Nehrenberg

IN an earlier publication' it was shown that the.. shape assumed by a volume of growing austenite is inherited from the prior structure. The matrix grains of pearlitic microstructures are equiaxed, and austenite grows in an equiaxed manner in these prior structures. Martensite and bainite, on the other hand, have an acicular grain structure, and the austenite produced in such structures grows in an acicular manner. In the discussion of this paper' it was pointed out that in cold-rolled tempered martensite, austenite grows in an equiaxed, rather than an acicular manner. The results of an experiment carried out to arrive at an understanding of this behavior are illustrated by the micrographs. Fig. 1 shows the acicular microstructure produced by heating tempered martensite to a temperature within the Ac1-Ac3 range, 1350°F. When tempered martensite is cold rolled, then heated to the same temperature, the equiaxed structure shown in Fig. 2 is produced. A sample of cold-rolled tempered martensite heated at 1350°F just long enough for the formation of a small amount of austenite is shown by Fig. 3 to have an equiaxed (recrystallized) ferrite grain structure. The small particles of. austenite which formed at 1350°F in the equiaxed ferrite matrix are likewise equiaxed. Thus, the equiaxed growth of austenite in cold-worked tempered martensite is not a contradiction of the principles described in the previous paper, for the growth pattern reflects the matrix grain structure existing at the time of austenite formation. References A. E. Nehrenberg: The Growth of Austenite as Related to Prior structure. Trans. AIME (1950) 188, pp. 162-174; Journal of Metals (January 1950). 2 J. R. Vilella and R. A. Grange: Discussion of ref. 1. Trans. AIME (1950) 188, pp. 1378-1381; Journal of Metals (November 1950).

Jan 1, 1953

By H. E. Rowen

As high grade iron ore deposits dwindle and costs rise, sintering becomes more and more important. The steel industry is now faced with beneficiation problems once peculiar to nonferrous work. Succeeding articles describe recent advances in this field. Here is presented the first chapter of a history still being written. SINTERING, for the purpose of this discussion, is defined as the art of burning a solid fuel with 90 to 95 pct ash content. Considering problems of combustion involved in keeping a home furnace burning properly with 12 to 20 pct ash in the fuel, it is evident that combustion represented by the definition has to be right or nothing is going to happen. Our forefathers discovered that many ores containing metals essential to the steadily rising standards of living were associated with elements such as sulfur and arsenic, which had to be removed before refining. This they did by utilizing the solid fuels they had available-the sulfur or other readily combustible components-to create roasting heat. One of the early methods is demonstrated in an old woodcut of the roast heap, Fig. 2. Ore was broken into chunks, piled on an ignition layer of solid fuel-logs in this case-and then. ignited. The sulfide ores roasted as the sulfur burned out. As shown in the background, the countryside was rapidly denuded of all vegetation by the great quantities of SO2 and other liberated gases.

Jan 1, 1961

By Albert F. J. Bordeaux

This paper briefly describes the general outline of cyaniding silver-ores in Mexico, with special reference to personal experiments made in the Temascaltepec district. The most important papers on the subject deal with cyaniding gold-silver ores, the gold predominating in value, so that the treatment is nearly the same as for gold-ores, the losses of silver being considered of little importance. I describe here the treatment of silver-gold ores containing very little gold, which is more general in Mexico than elsewhere. The cyanide treatment, which was so successfully applied to gold-ores, did not succeed immediately with silver-ores on account of their varying composition. Gold occurs in nature usually in the native state, while silver occurs generally in combination with sulphur (argentite), and various combinations of sulphur, antimony, and arsenic. In former times there mas a complete difference in the treatment of gold-ores and silver-ores. Amalgamation, which was successful with gold-ores, was generally inadequate with silver-ores. The usual treatment in Mexico for silver was the patio process, the theory of which was satisfactorily explained only quite recently by Mr. Ortega and others. General Outline of the Cyanide Treatment. The general tendency of the present practice is to slime the silver-ore as much as possible, and in order to obtain a higher efficiency, with less loss of cyanide, and greater speed, the following lines are observed: 1. Crushing by stamps with 30- or 40-mesh screens, then crushing by Huntington or Chilean mills, through 60- or 80-mesh screens. 2. Concentration upon vanners.

Jan 1, 1910

By Frank Firmstone

WE found it necessary, in December, 1874, to repair the upper part of the lining in No. 5 furnace at Glendon, and, as we succeeded in doing it with comparatively little trouble, a description of the plan followed may be of service to those having a similar operation to perform. On two opposite sides, as shown by the sketch, the lining was completely gone for a height of about four feet, below which it increased gradually in thickness, being nine inches thick about three feet lower down. On a plane at right angles to the section drawn, the brick were nowhere entirely gone, but were in some places not more than two or three inches thick, being still sufficient to sustain the upper part, where the brick, being above the level of the stock, were not at all worn. The furnace was blown down, so that when we cast and closed the tuyeres, about 7 A.M., on December 8th, the top of the stock was about twenty-four feet below the filling-plates. The walls were quite hot, and a good deal of gas was given off for several hours after the tuyeres were closed. The hopper and bell were thrown into the furnace, and were covered by filling several charges of cold stock over them, which at once greatly cooled off the top of the furnace. A wrought-iron pipe, thirty inches in diameter, in five sections, each six feet long, was then put down, and made to stand upright, as nearly as possible in the centre of the furnace. Around this we filled a double charge of coal, taking care to heap it up next the pipe, and let it get thinner as it got to the walls. This was covered with about two feet of fine ore, leaving the lowest joint in the pipe entirely uncovered. We were now ready to put in our scaffold to get at the

Jan 1, 1876

By Paul C. Ragland, P. Geoffrey Feiss

The Piedmont province of the southern Appalachians is the focus of interest for many exploration geologists. In the past, only those deposits with significant surface exposure were exploited. Thus, few deposits have been found and relatively little exploration has been conducted in recent years. Modern geochemical and geophysical techniques can alleviate this problem of concentrating on exposed ore bodies by allowing us to "look through" the soil and saprolite to detect the presence of significant mineralization at depth. This paper will attempt to evaluate the feasibility and effectiveness of several geochemical exploration techniques in the Piedmont province of Cabarrus and Stanly counties, N.C. The area chosen for study is shown in Fig. 1, lying almost wholly within the Mt. Pleasant quadrangle, N.C. The area is on the eastern boundary between the Charlotte belt, a zone of plutonic and intermediate grade metamorphic rocks, and the Carolina Slate belt, a series of complexly interbedded volcanic and sedimentary rocks of predominantly low metamorphic grade. The area is considered to be an early Paleozoic active, continental margin. 1 As is typical of most of the piedmont, outcrop is sparse. Figure 2 is a sketch map of the general geology of the area under study, showing the Charlotte belt rocks in the north-western quadrant and slate belt rocks to the east. Within the area are a number of old mines and prospects, the most famous of which are the Furniss and Phoenix mines in Cabarrus County. All are reported to have contained Au and Cu. Ag and Pb were reported from some. A summary of the deposits is given in Table 1.

Jan 6, 1979

By A. S. Learoyd

THE Anthracite Division, Bureau of Distribution, of the United States Fuel Administration, came into existence about Oct. 20, 1917. There had been no definite policy determined upon and the distribution had been carried out by the producers and distributors of this fuel as under normal conditions. The domestic sizes had been shipped from the beginning of the coal year on Apr. 1 in about their usual proportions to the various sections of the anthracite consuming territory of this country, which, in a general way, extended as far west as Nebraska and Montana, and in the south along the Atlantic seaboard to Florida. With the advent of cold weather, about the middle of November, acute shortages commenced to develop all over the northeastern section of the country, due to largely increased demand by the public in general, to enormously increased population in centers where industrial war activity was concentrated, and by the needs of the war industries themselves. Commencing with the early part of December, this demand was aggravated by extreme low temperatures and heavy snow; and the production decreased for the same reasons. From that date until the change in the weather, about the latter part of February, it was simply a question of getting coal into communities as emergencies occurred, to take care of individual cases. No definite plan of distribution could be followed. The coal mined between Apr. 1 and Nov. 1 had been distributed as mined and, therefore, only current production was available for distribution. The Anthracite Division, during this period, consisted of a Director, two assistants, together with an office force of seven or eight clerks and stenographers.

Jan 8, 1919

By John E. Udd

Introduction During the very long period in which man has mined minerals from the crust of the earth, falls of ground and collapes of under- ground workings have been the causes of a significant part of those accidents which have resulted in either death or in injury. At present, because of improvements in the approaches to the design of underground structures, in equipment, and in attitudes towards accident prevention, the proportion of accidents due to instability of rock is probably far less than it was historically. Nonetheless, in spite of the many advances which have been made, instabilities still account for about one-quarter of all fatalities, and one-tenth of all of the injuries, in the minerals industry. The means must be found whereby both the numbers of accidents and the accident rates due to falls of ground can be reduced to the lowest levels possible. At the outset it should be stated that, short of suspension of all mining activity, it will probably never be possible for us to eliminate accidents completely. Most human enterprise involves unknowns and risks, and mining is no exception. A certain number of accidents, then, must be viewed as the inevitable consequence of our attempting to work with unknowns and to make decisions that involve uncertainties. However, in retrospect, many instabilities can be attributed to factors which could have been within our control. The preventable accident must be eliminated. It should be our goal that we make every effort to direct our skills and technology to the creation of a safer working environment and should be constantly striving to

Jan 1, 1983

By J. B. Umpleby

The subject of reservoir energy and its efficient utilization has been well explored in many papers. The present effort, therefore, is limited to a summary of existing information combined with an emphasis of the probability that the relative importance of controlling factors will change with advancing knowledge. Consequently the necessity for flexibility in laws and regulations, inherent in the problem, is emphasized. Definitions Many terms have been widely used in the literature without having been specifically defined. For example, confusion exists in the use of ((reservoir energy" and "gas energy." The latter is much more limited in meaning than the former. Other terms have been variously used. Consequently, I shall preface my remarks with definitions of a few of the more pertinent terms. Reservoir energy is that force or forces, active or potential, that is native to the reservoir and has the power to move oil through the reservoir rock. The energy may result from expanding gas, from hydrostatic head, from the weight of overburden, or from any other source. Gas energy is the expansive power of gas when pressure is reduced. It is one type of reservoir energy. An oil reservoir is that part of a geologic formation or formations in which oil occurs in commercial quantities wholly surrounded by nonproductive rock. The essence of this definition is effective separation rather than remoteness and under it oil reservoirs may be superimposed in the same oil pool. Conservation of reservoir energy means primarily its maximum use in the production of oil. Unit operation is a plan of development and production, which embraces an entire oil reservoir under a unity of engineering control. It is distinct from unitization, which has to do with arrangements of organization and equities to make unit operation possible in areas of divided ownership.

Jan 1, 1934

By Carl H. Beal, E. D. Nolan

In February, 1918, the conclusion was published by Lewis and Beal "that wells of equal output on the average will produce equal amounts of oil in the future, regardless of the ages of the wells." This conclusion was based upon the study of data collected principally in Oklahoma and was not known at that time to be true for other oil fields. An abundance of statistical proof was later collected by the senior author of the present paper, which showed that the conclusion was undoubtedly well founded and that it applied to other fields as well. Accordingly, it was later restated2 as the "law of equal expectations" as follows: "If two wells under similar conditions produce equal amounts during any given year, the amounts they will produce thereafter, on the average, will be approximately equal, regardless of their relative ages." Although only scanty data from the California oil fields were available at the time this publication was prepared, sufficient information was analyzed upon which to base the insert on Fig. 80, which showed beyond a doubt that the law held at least for a part of the Midway oil field in California. Recently the authors have collected more complete data in California, and it is the purpose of this paper to explain the method used in demonstrating the truth of the law and, in addition, to give several methods by which curves constructed in accordance with this law can be used in a practical way with ease and accuracy. The Family Curve The law of equal expectations means that each individual of a group of wells producing under similar conditions will decline along approximately the same type of curve, the rapidity of decline varying with the output

Jan 1, 1921

By Dever Ashmead

ENGINEERS, operators, miners, and others di-rectly interested in mining will readily agree that more of well-directed illumination in mines will result in a reduction of accidents and general im-provement in the working conditions, comfort, and effi-ciency of those employed underground. Progress has been made in the amount of illumination from individual lamps carried by miners. The candle, which a great many of us can remember as the general method of lighting, was replaced by the oil lamp or torch, later by a specially prepared oil known as "Sunshine," and eventually by the carbide cap lamp. The metal mines still present a field for progress from the standpoint of general illumination, particular-ly those mines having high stopes. Attention is being more and more focussed upon the advantages of im-proved lighting in mines, in order that the underground employee may benefit as the factory workers have al-ready done. The management is vitally interested in the morale of its employees, the reduction of costly accidents and increased production, all of which, judging by results in other industries, will be sub-stantially benefitted through the means of improved general illumination. From data available to the writer, 40 to 50 per cent of the accidents in the metal mines occur at the face; they may be due to roof falls, movement of loose ore, loading of cans, handling of tools, etc. Very probably a large proportion of these accidents may be attributed to lack of light. If sufficient illumination had been present the employee could have seen what was happen-ing and taken the proper precautions. The introduc-tion of better illumination means better visibility, de-crease in accidents, and increase in efficiency.

Jan 6, 1928

By Albert Walcott

THE success of various operations in the manufacture of optical glass depends, in a large measure, on the ability to maintain proper heat control. A good pyrometer system is, therefore, a very necessary part of the equipment needed. Men of long experience in dealing with high temperatures, who have acquired through constant practice the ability of judging approximate temperatures by means of color, are undoubtedly valuable, but even the most competent are not as reliable as a good pyrometer system. They admit that their ability to judge accurately varies from day to day and that their judgment is affected considerably by the condition of the sky, whether it is clear or cloudy. Besides, where it is a matter of only a few weeks to train a man to operate a pyrometer system, it takes about as many years to train him to judge temperatures by the state of incandescence. The pyrometer outfit in use in the glass plant of the Bausch & Lomb Optical Co. consists of the following: Platinum elements, optical pyrometers; base-metal elements, indicators, potentiometers, and recording pyrometers. Platinum Elements and Optical Pyrometers.-Temperature control in - the melting operation is of such great importance that it is very desirable to know the exact temperatures, relative temperatures being of little value. The use of the platinum element is to determine the rate of heating or cooling of the furnace. The platinum couple is installed in either the crown or the wall of the furnace. It is placed first in a porcelain protecting tube and this is placed in a permanently fixed fireclay tube projecting from 1 1/2 to 2 in. into the fire-chamber. It has been found impractical to use the platinum couple for determining exact temperatures of the melting furnace, for the platinum element deteriorates rather rapidly at the high temperatures used, 2500° to 2700° F. (1371° to 1482° C.). When protected and installed as described, though,

Jan 9, 1919

By Roswell Johnson

WHAT becomes of the water which must have filled the oil and gas sands at the time of deposition, has long puzzled students of oil and gas and has found expression in Munn's well known article on the hydraulic theory. Both Munn and Clapp have pointed out that in the Appalachian field the deeper sands carry increasingly less proportionate amounts of water. It seems to me probable that the principal source of oil and gas has been in the shales in proximity to the sands which now contain these products. The sand spits which mark off the lagoons from the sea comply particularly with the requirements of a limited sand imbedded in shales rich in organic matter. Cunningham Craig has objected to this view that the rich organic muds of lagoons are found only at the surface. That such muds do extend to considerable depth 1 am assured by Prof. Douglas W. Johnson, who has made an extensive study of the Atlantic Coast marshes. As any particular sand body becomes weighted by a heavier and heavier overburden, the result of increasing deposition, a part of the very large percentage of water in the uncompacted sand and mud is forced pout. The water percentage of freshly settled mud is vastly higher than that of the resultant shales, or even of a very porous sand. If beds of less compressible material meet or underlie the shales in question, there will. frequently be a lateral motion along such beds to some point where the upward movement will be resumed. We find in our laboratory work here that oil, gas, and water have extremely slight capacity for gravitational sorting while in a state of rest but when moving the gravitational sorting is readily accomplished. As the oil, gas, and water pass a body of larger pores, the gas, owing to its lack of capillary attraction, is retained in .the large pores.

Jan 2, 1915

By Lawrence Addicks

AT the San Francisco meeting of the Institute last year, I presented, through the courtesy of Dr. James Douglas; some results of experiments on the roasting and leaching of concentrator tailings. After it became apparent that flotation rather than leaching was clearly the better method of handling the particular problem under consideration, before dismantling the experimental equipment, some data were secured on roasting and leaching the concentrate itself in competition with smelting. Some of the results obtained are given in the following paper and they a re of particular interest at this time in. view of the large quantities of flotation concentrates with their somewhat difficult smelting characteristics now being produced. A complete wet process? consists of roasting and leaching the calcines in dilute sulphuric acid produced from the roaster gases, roasting the residue with salt and leaching with dilute tower liquors (the well-known Longmaid-Henderson process) and recovering the copper, silver and gold by cementation or electrolysis or a combination of both. It is evident, however, that the residue from the first leaching, carrying about 20 per cent. of the copper and all of the silver and gold, can be smelted if preferable. In considering the application of the scheme to individual cases, it must be remembered that freight plays a. large part in any reduction process wherein smelting is not conducted at the, mouth of the mine, and that it is not practicable today to build small smelting plants for individual operations. The experiments may be grouped under four main heads: Roasting, leaching, chloridizing residue, and recovery of copper from solutions. The products of two concentrators were used: The Nacozari concentrates were the product of a large modern mill not using flotation, the copper mineral being largely chalcopyrite; and the Tyrone concentrates, the product of an experimental mill including flotation, the copper mineral being chiefly chalcocite. Typical analyses would be as follows:

Jan 9, 1916

By N. B. Pilling, R. E. Bedworth

The corrosion of metals is one problem on which time and thought have been expended for many years. In the effort to avert the destructive action of a hostile environment, attention has been directed almost entirely to the conditions under which most metallic structures are called upon to perform, and the extensive and complicated phenomena attending the corrosive action of atmospheric agencies, acting at the ordinary atmospheric temperatures, have been studied, but there is unanimity of opinion regarding many fundamental facts. One neglected phase is the corrosive action of various gases upon metals exposed to temperatures considerably higher than the atmospheric range, and more especially the attack of atmospheric oxygen upon exposed metallic surfaces. That the problem is difficult is connoted by the practical dominance of industrial electric heating by alloys of one type (nickel-chromium). Proprietary interest may account, in part, for the paucity of information available upon even the most general factors determining the behavior of metals and alloys when exposed to such exacting conditions. The present paper gives some conclusions reached as the result of experimental work, extending over several years, on the mechanism and contributory factors of the high-temperature oxidation of a number of simple unalloyed metals; it is free from experimental detail and proof. High-temperature metallic oxidation may be considered as a phase of metallic corrosion. The scheme outlined below, in which corrosive agent and environment are the principal criteria, is one way of analyzing the several groups of corrosion phenomena. Erosion.—Disintegrating or destructive action by physical causes. Corrosion.—Disintegrating or destructive action by chemical causes. Low-temperature Corrosion.—Solid participating phases essentially immobile: (a) Gaseous agent; (b) liquid agent: action electrolytic and action non-electrolytic. High-temperature Corrosion.—Solid participating phases possess diffusive mobility: (a) Liquid agent; (b) gaseous agent: reducing gases, oxidizing gases. (1) Water; (2) miscellaneous elemental and combined oxygen.

Jan 1, 1923

By R. E. Bedworth, N. B. Pilling

The corrosion of metals is one problem on which time and thought have been expended for many years. In the effort to avert the destructive action of a hostile environment, attention has been directed almost entirely to the conditions under which most metallic structures are called upon to perform, and the extensive and complicated phenomena attending the corrosive action of atmospheric agencies, acting at the ordinary atmospheric temperatures, have been studied, but there is unanimity of opinion regarding many fundamental facts. One neglected phase is the corrosive action of various gases upon metals exposed to temperatures considerably higher than the atmospheric range, and more especially the attack of atmospheric oxygen upon exposed metallic surfaces. That the problem is difficult is connoted by the practical dominance of industrial electric heating by alloys of one type (nickel-chromium). Proprietary interest may account, in part, for the paucity of information available upon even the most general factors determining the behavior of metals and alloys when exposed to such exacting conditions. The present paper gives some conclusions reached as the result of experimental work, extending over several years, on the mechanism and contributory factors of the high-temperature oxidation of a number of simple unalloyed metals; it is free from experimental detail and proof. High-temperature metallic oxidation may be considered as a phase of metallic corrosion. The scheme outlined below, in which corrosive agent and environment are the principal criteria, is one way of analyzing the several groups of corrosion phenomena. Erosion.—Disintegrating or destructive action by physical causes. Corrosion.—Disintegrating or destructive action by chemical causes. Low-temperature Corrosion.—Solid participating phases essentially immobile: (a) Gaseous agent; (b) liquid agent: action electrolytic and action non-electrolytic. High-temperature Corrosion.—Solid participating phases possess diffusive mobility: (a) Liquid agent; (b) gaseous agent: reducing gases, oxidizing gases. (1) Water; (2) miscellaneous elemental and combined oxygen.

Jan 1, 1923

By Wolfram Ruff, H. A. Schwartz

THE spheroidal form of the temper carbon nodules in malleable cast iron and of the graphite mottles of "mottled" cast iron suggests that in both all the graphite in a given mottle or nodule grew from a single center of crystallization or nucleus. ‡ There is, however, a distinct metallographic difference between the mottle and the nodule; the area of mother metal impoverished in combined carbon by the crystallization of graphite in a mottle is practically coextensive with the ramifications of the graphite, while the impoverished zone of metal corresponding to a given nodule is always larger, and usually much larger, than the approximately spherical mass of graphite crystals forming the nodules. Furthermore, the mottle probably is formed during freezing and the nodule almost always at a considerably lower temperature. Assuming that the nodules or mottles can be used as a measure of the existing nuclei (capable of germination) we propose to record certain observations as to the graphitizing reaction in the light of the number and habits of growth of these nuclei. The present authors, in cooperation with others 1-7, have reported upon various cognate aspects of the problem. The fact that temper carbon is a mass of flakes and not a solid granule has become well recognized since the introduction of an improved polishing technique8,9,10 for cast iron. The problem of deriving from the circular planar intercepts

Jan 1, 1935

By John Birkinbine

Modern advances in practically all lines of industrial develo1)ment have occurred in such rapid succession, and have been accepted so readily as accomplished facts, that a retrospect surprises us, by showing how comparatively few of the acknowledged factors of improved conditions may be considered as old. While these advances have not been confined to any country, they have been more pronounced in some than in others, and nowhere more so than in the United States, the population of which, having multiplied nearly three-fold between 1870 and 1910, demanded a proportionately greater increase in materials, supplies, and manufactured products. It therefore appears desirable to discuss mainly conditions in the United States, as concrete evidence of industrial progress throughout the world. Looking backward for but three generations, me mar trace the introduction and developmerit of canal- and steamboat-narigation ; railroad-transportation; artificial illumination beyond that f'urnished by candles and animal-oils; quick communication by mail, and subsequently by telegraph or telephone; the manufacture of iron, beyond forms of small dimensions; the production and utilization of steel in large quantities; the economic use of mineral fuel, oil and gas, etc. The practical coincidence of the fortieth anniversary and the 100th technical meeting of the American Institute of Mining Engineers, offers temptation to recall and compare the conditions of milling and metallurgy in or about the years 1871 .and 1911. A complete résumé would cover phenomenal changes in mining-methods and equipment by which the output of individual exploitations has grown from scores to hundreds and even thousands of units in equal time-intervals. Extension of operations in depth and area, demanding machinery of great power and efficiency, high percentage of extraction, utilization of what

Jan 1, 1912

By Frederick Crabtree, A. R. Powell

When Professor Stoek asked for a paper on the above subject, it was too late to prepare by June 1, or near that time, one that would invoive any appreciable amount of experimental work or original research; but the suggestion was made that a review of the literature bearing on the subject might be submitted in good time, and that later this could be supplemented by any experimental data obtained during the summer, if experiments were carried out. In accordance with this suggestion, there are submitted the following notes on references found in the literature of recent years bearing on sulfur in gas. It is to be understood that, in general, these notes express the opinions of the authors whose papers are abstracted, not necessarily the opinions of the abstractors. Very little published information was found bearing directly on producer-gas sulfur, so this has been supplemented, in certain phases of the subject, by references to illuminating gas. Methods of analysis and processes for the elimination of sulfur from the gas are, without much doubt, very closely related in these two products. As in illuminating gas, sulfur is found in producer gas mainly as hydrogen sulfide, mixed with a much smaller and variable quantity of carbon bisu1fide.l The presence of minute quantities of other organic-sulfur compounds has been intimated, but no definite statement is made concerning these. The amount of sulfur present in producer gas is variable and depends on several conditions. The primary factor is the quantity of sulfur in the fuel, but the form in which the sulfur exists, the temperature of the producer, the air-steam ratio, and the efficiency of the scrubbing process are all determining factors. When the coal used contains less than 0.5 per cent. of sulfur, the sulfur in the gas will not exceed the quantity found in the average illuminating gas.2 Sulfur in producer gas may safely run higher than that in coke-oven gas, due to the lower-flame temperature

Jan 1, 1920