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By E. W. Pehrson, J. W. Furness

THE method of presentation in the accompanying charts is based upon the well-known formula: production plus imports minus exports equals apparent consumption. Thus for each area for which data are shown there are two columns of equal height, one representing production plus imports, the other apparent consumption plus exports. Usually no account has been taken of increases or decreases in stocks. All columns and flow lines are drawn to a linear scale which is supplemented by figures showing the actual quantities represented. Owing to the small area occupied by the European countries on the world map it was impossible to show the details of the trade of the individual countries. All of Europe (except Russia), therefore, is shown as a single unit. However, statistics of production and consumption indicated elsewhere on the charts show the degree of self-sufficiency enjoyed by the major European powers.

Jan 1, 1936

By T. Sterry Hunt

This remarkable mine, to which attention has lately been drawn, is situated not far from the New River, in Ashe County, North Carolina, on a spur of the Blue Ridge which lies between the main crest of this name and the so-called Iron Mountain, a part of the Unaka or Smoky Mountain range. It is on a true fissure-lode, which cuts the strata of gneiss and mica-schist of the region. These, which have the lithological characters of what I have called the Montalban or White Mountain series, have here a dip of about forty-five degrees to the southeast, while the lode is vertical, with a course north 60' east. Both the country-rock and the lode, as is usual in this region, are decomposed to considerable depths; and the latter exhibits a cap of hydrous peroxide of iron or gossan, blocks of which, left by the denudation of the softer inclosing rock, are scattered over the surface, and first called attention to the locality as a source of iron ore. In sinking upon this lode, it was found that the porous gossan at a certain depth became charged with carbonate and red oxide of copper, and lower down was replaced by sulphuretted ores of this metal of remarkable richness. This deposit was worked for copper, in an irregular manner, before the late civil war, but was afterwards abandoned, and only reopened during the present year, by Messrs. S. S. & J. E. Clayton, of Baltimore. The outcrop has been traced for 1900 feet, and the sulphuretted copper ores have been met with in five shafts in a distance of 661 feet, a drift having moreover been carried for the above distance through the solid ore. The breadth of the lode, so far as opened, varies from six to eight feet to fourteen feet in places, and that of the outcrop of gossan is, in some parts, twenty feet. After comparing this deposit with the copper mines of Ducktown, Polk County, Tennessee, and those of Carroll County, Virginia, it is evident that we have, at Ore Knob, to do with the same kind of black ores as were met with in these mines, and will be noticed further on, Beneath the gossan, at Ore Knob, is found, in some parts, an iron-black, friable, drusy, crystalline, sulphuretted ore, inclosing grains of quartz, garnet, and magnetite, besides a black non-magnetic mineral, not attacked by nitric acid. This ore contains about 36 per cent. of copper, and portions have the mineralogical charac-

By John Birkinbine

The early history of the mining and metallurgical industries of Pennsylvania is so intimately associated with the section of the State in which we meet, that a brief resume of a few of the important historical facts, and a reference to some of the more modern enterprises, in which members of the Institute have been largely concerned, seem appropriate to this occasion. It is just two hundred years since the publication of the earliest mention of the manufacture of iron in Pennsylvania. What kind of iron this was, or where or by whom it was produced, is uncertain. The only record of it is the following verse, quoted in the admirable work of Mr. James M. Swank,* from a poem published in 1692: " A certain place here is, where some begun To try some Mettle, and have made it run, Wherein was Iron absolutely found, At once was known about some Forty Pound." One who stood one hundred and seventy years ago on the summit of this Neversink Mountain † (had the atmospheric conditions been favorable, and the timber somewhat removed) might have noticed in the daytime the smoke, or at night the reflection, from the fires of the first successful Pennsylvania iron enterprises, scarcely 15 miles to the south, viz.: Rutter's bloomary forge, built in 1716, and the Colebrookdale blast-furnace erected in 1720, respectively 3 and 8 miles distant from Pottstown. Here the pioneers of iron production in the State which has so long led, and still leads all others in this manufacture, had their trials and successes ; and it may be a satisfaction to some who bewail a present depression in trade, and the low prices now ruling, to recall the fact that in 1731 pig-iron is reported to have been sold ''in large quantities" at the Colebrook-

Jan 1, 1893

By Henry M. Howe

In discussing the classification of iron to-day, we are to leave out of consideration the general division into non-malleable or cast iron and malleable iron, as to the adequacy of which no question has been raised; and to confine ourselves to the subdivisions of malleable iron. This has been classified, according to the extent to which the properties imparted by carbon are present (viz., resilience, hardness,strength, and, above all, the capacity for being hardened by sudden cooling from a high temperature), into (1) wrought iron which cannot be hardened, and (2) steel which can be hardened; and this classification I shall, for briefness, term the carbon classification. Until within a few years all authorities, both metallurgical and general, have concurred in explicitly recognizing the carbon-given qualities, and preeminently the capacity for being hardened, as the essential qualities of steel; this is laid down with clearness by every writer on the subject. For several years this old classification has not been sufficient to meet all our needs, since the genius of Bessemer, Siemens, and, I may add, Holley, has produced wrought iron which has been perfectly melted, and thus freed from certain mechanical adhering impurities. This causes what we call homogeneousness for want of a better word, and gives rise to many important qualities which the old wrought iron had not; qualities universally recognized, though not readily described. I shall, for briefness, style them the fusion qualities, and a classification based on them, a fusion classification. These qualities render the new product so vastly superior, for most purposes, to the wrought iron formerly known, that it is neces-

By John Furness Park

The mining district is located in the northeasterly part of Nevada, between the Jarbidge River on the west and the East Fork of the Jarbidge on the east. The northern boundary of the district is but a few miles south of the Idaho state line—the gold-bearing area extending from this point south, for 5 or 6 miles. • The Jarbidge Mountains, in which the ore deposits occur, range from 5000 to 11,000 ft. in elevation, the most important mines being situated about 7000 ft. or higher. The town of Jarbidge lies along the Jarbidge River and is reached by stage from Rogerson, Ida., the nearest railroad point. During the summer months, the camp may be entered from the south by way of Deeth, Nev., but no regular transportation facilities are available over this route. History The mineral deposits were not discovered until 1909, when D. A. Bourne, panning along the river bank, found gold in. the gravel at the mouth of a small stream flowing into the Jarbidge. He prospected in the vicinity of this stream, later known as Bourne Gulch, and shortly after located the North Star claims. During the following spring and summer (1910), the camp of Jarbidge grew from nothing to a town of 2000 people and the hills surrounding it were practically all taken up by mining claims. Most of the work done during the first year or two consisted of trenching and open-cut prospecting. Tunneling was started on a number of claims and many veins were uncovered. Mills were built and operated on a few properties, notably the Pavlak and the North Star. These ran only a few months, however, when they were closed down because of extraction and financial difficulties. A period of development followed in which the majority of the present producing mines were opened. The Elkoro Mines Co. acquired a number of claims in 1915 and started work on the present mill in 1917. Since that time other properties have been taken over until this company is by far the largest operator in the district. Only one other company is now actively engaged in mining, the Bluster Mining & Milling Co., which has

Jan 1, 1925

By Clarence A. Seyler

The object of all classification is to group together things which are alike, and separate those which are unlike. This object is essentially a practical one, enabling us to apply past experience to new conditions. Many costly large-scale experiments lose half their importance for want of proper description of the coal used, and the consequent impossibility of predicting that other coals will behave in the same way. I do not, therefore, make a fundamental distinction between "scientific'' and "use" classifications, except in so far as use depends on conditions, such as size or impurities which are not related to the nature of the coal substance itself. The characters chosen to define the classes of coal must be such as are accompanied by as many other properties as possible. It is not to be expected that any system of classification will enable us to predict every property of coal, since all specimens have an individuality of their own. But specimens can be grouped by a number of resemblances into species. Further, species which resemble each other can be grouped into genera. Elementary Composition as a Basis of Classification There can be little doubt that the ultimate or elementary composition of "pure coal" is the best basis of classification. It was soon after the perfection of the method of elementary analysis of organic substances by Liebig that Regnault, the distinguished chemist and physicist, laid down the principle that coals of the same kind vary only between narrow limits of elementary composition. This is still the widest generalization that can be made about coal. Upon it the metallurgist Gruner based his classification. In some quarters the value of the ultimate composition was denied, Stein going so far as to say that it teaches us nothing of importance about coal. One still hears statements that it is like crushing a work of art in a mortar and analyzing the powder, or like counting the number of times a given letter occurs in a sentence. Such comparisons are misleading, and the criticism might be applied to organic chemistry as a whole. Nor is the existence of isomerism, or of entirely different substances which

Jan 1, 1928

R.. B. T. KILIANI, New York, N. Y.-I do not care to discuss Mr. Taggart's paper in the light of theory, as that has been very well done by Prof. Bell,1 but I should like to criticize some of his conclusions, in the light of actual operating practice at plants all over the country. 1. Mr. Taggart's first conclusion is that in crushing average ore, the character of the gangue has little effect on the efficiency of the mill. This, I believe, is not in accordance with the usual practice, since in crushing a hard ore the capacity will be much reduced below what it would be with a softer ore, while the power consumed will be practically independent of the character of the ore, being proportional only, to the load of ore and balls in the mill. 2. Mr. Taggart's second criticism is that the Hardinge mill is not suitable for grinding soft, tough material. In answer to this I might mention that the mill is being used for grinding tough, dnctile material, such as metallic aluminum, and also for grinding licorice root. 3. He says that the ball-mill works more efficiently on material of intermediate size, say 1/2 to 3/4 in., than on either coarser or finer feed.. This is true as to coarser feed. For the most efficient work, I believe that a ball-mill should be fed with material not coarser than 1 1/2 in.; it' will handle material up to 3 and even 4 in., but the reduction from 3 or 4 in. to 1 1/2 in. can be done much more cheaply and efficiently by rolls or disk crushers than in the ball-mill. 4. As to Mr. Taggart's fourth conclusion, that a greater ratio of reduction can be expected with feed of an intermediate size than with a coarse feed, I have not enough information to express an opinion. 5. His next conclusion is that steel balls are much more efficient crushing media than pebbles. Steel balls are undoubtedly more efficient for crushing coarse feed. On fine material they are also more efficient as to tons per horsepower crushed to 10-mesh, but on fine material I think it will be found that flint pebbles are cheaper than cast-iron balls, per ton of ore, although there will be a saving in power per ton by using cast iron instead of flint. The increased cost of crushing with cast iron will be due to the higher cost of iron at the present time. 6. Mr. Taggart's sixth conclusion coincides with present practice, that steel balls will grind as fine or finer than pebbles when working on the same feed.

Jan 1, 1918

By Daniel M. Bass, Paul B. Crawford

Laboratory investigations have been made to study the effect of variations in fluid characteristics, gas saturation, water saturation, and water injection rate on oil recovery by water flooding. Three synthetic gas-saturated crude oils having bubble points of 860, 1,540 and 1,885 psi were used as reservoir fluids. Repeated tests were made in which a and pack, saturated with water and synthetic oil, was produced by solution gas drive followed by water flooding at various pressure levels. Oil recovery by solution gas drive and subsequent water injection is shown to vary with the pressure and rate at which the water flood is conducted. The pressure at which optimum flooding conditions exist is shown to be a functiotl of the physical characteristics of the reservoir fluid. For the systems studied, increases in oil recoveries of near 10 per cent were obtained by flooding at the most desirable conditions. Va- riations in initial water saturations gave results similar to those in the literature. INTRODUCTION Most of the waterflooding studies investigating means of improving present exploitation processes have been conducted at low pressures with little effort to simulate reservoir conditions. Holmgren and Morse' performed a waterflooding study at 300 to 500 psi wherein the gas saturation was created by injecting gas, letting dissolved gas evolve from the oil, and then flushing the core with "live" oil until the desired gas saturation was obtained. Their results show increasing oil recoveries with increasing gas saturations. Data presented by Guerrero' and Kennedy, et al, indicate that in some instances water flooding at approximately 500 psi below the original bubble point results in a lower residual oil saturation than is obtained when water flooding above the bubble point. In their work gas saturations were created by primary depletion. By correcting low pressure flooding data for fluid shrinkage, Dyes found that a maximum oil recovery may be obtained by flooding with initial gas saturations of from 7 to 12 per cent. The purpose of this work was to determine the variations in oil recovery caused by initiating a waterflooding program at various stages of primary depletion of a core. This is a part of a more comprehensive study of obtaining criteria for determining when to initiate a pressure maintenance program and what fluids to in-ject. EQUIPMENT A schematic diagram of the apparatus is shown in Fig. 1. Fluid transfer was accomplished with metering pumps. Pressure control was ob-

Jan 1, 1957

By Raymond B. Ladoo, C. A. Stokes

Bruce C. Netschert—It is unfortunate that the authors of this paper consider it necessary to begin with an expression of concern over possible false interpretations of the word "economics." In their preoccupation with the definition of economics, they have adopted a definition of mineral economics which is, to say the least, unduly narrow. Just as the broad field of economics is not confined to a study of the profitability of business concerns, but includes the problems of production, distribution, and consumption as they pertain to society as a whole; so an inclusive definition of mineral economics should not be confined to the determination of the profitability of mineral-producing and processing enterprises, but should include the significance of the unique characteristics of mineral resources as raw materials for the use of society. Such features as the exhaustibility and localized, haphazard occurrence of deposits, the existence of a secondary (scrap) supply, and the increasing cost of operation during the life of a mining enterprise are obviously factors which concern those businesses which are producing mineral raw materials, since they partially determine the profitability of such enterprises. They are also of concern to society as a whole, however, as characteristics of one of the basic elements of the economic system. In the last analysis, the contribution which mineral economics can make as a means of determining and guiding social policy with respect to the production and utilization of mineral resources is perhaps more important than its use as a basis for determining the cost accounting procedure of individual firms. The list of "economic factors peculiar to the industrial minerals" which the authors present is in reality an application of such a broad definition of mineral economics. An inconsistency appears, however, in the inclusion of items 8 and 9 in the list. As this writer sees it, the point in question is: What influences do the characteristics of industrial minerals have on the characteristics and operating procedures of industrial mineral enterprises which are not present in the metallic mineral field? In answering this question with items 8 and 9, Messrs. Ladoo and Stokes do not recognize that there are two distinct types of differences between the two fields of enterprise. There are, on the one hand, important basic economic distinctions due to inherent economic characteristics of industrial minerals which do not pertain to metallic minerals. On the other hand are those characteristics of the industrial mineral enterprises peculiar to them alone, but which are superficial and temporary, in that they may be changed or eliminated at the discretion of the managers of those enterprises. The lack of adequate research and development in industrial mineral production, processing, and marketing (item 8) is not due to an inherent characteristic of industrial minerals. It is true that one may perhaps describe the field of industrial mineral enterprise in terms of such a deficiency, just as one could, until recently, point to a similar lack of research and development in the coal industry; but unless it can be shown that the deficiency has been wholly or partially due to the very nature of industrial minerals themselves it is not an "economic factor peculiar to the industrial minerals" but a temporary characteristic peculiar to the industry. In the writer's opinion, the authors have not demonstrated that the former relationship exists. Similarly, item 9, the "influence of technologic developments," is also not inherently peculiar to industrial minerals. Nowhere in the discussion of this item do the authors mention anything that is not equally applicable to the field of metallic minerals. This is not meant to imply that the specific technologic developments which the authors list are of equal significance in both fields. It does mean that such a statement as, "technological advances together with new consuming areas to provide markets make deposits commercially valuable which once were of no interest" cannot be considered as an argument that technological developments have significance in the field of industrial minerals alone. In considering the problem of stockpiling, the authors note that the stockpiling of nonstrategic materials might be desirable if future wartime needs could exceed domestic production capacity, but dismiss this as hardly adequate to justify such stockpiling. The problem, however, can be stated in broader economic terms, i.e., the real costs (as distinguished from the money costs) of prewar versus wartime production. In other words, it might well be that the labor and capital required to produce a given amount of a certain mineral raw material could be used more efficiently in another industry. In such a case it is obviously advantageous to stockpile the material in prewar times rather than forego the benefits of additional production in another line of endeavor during wartime under conditions which demand the optimum use of all resources, including manpower and capital. To the writer's knowl-

Jan 1, 1951

By Raymond B. Ladoo, C. A. Stokes

Bruce C. Netschert—It is unfortunate that the authors of this paper consider it necessary to begin with an expression of concern over possible false interpretations of the word "economics." In their preoccupation with the definition of economics, they have adopted a definition of mineral economics which is, to say the least, unduly narrow. Just as the broad field of economics is not confined to a study of the profitability of business concerns, but includes the problems of production, distribution, and consumption as they pertain to society as a whole; so an inclusive definition of mineral economics should not be confined to the determination of the profitability of mineral-producing and processing enterprises, but should include the significance of the unique characteristics of mineral resources as raw materials for the use of society. Such features as the exhaustibility and localized, haphazard occurrence of deposits, the existence of a secondary (scrap) supply, and the increasing cost of operation during the life of a mining enterprise are obviously factors which concern those businesses which are producing mineral raw materials, since they partially determine the profitability of such enterprises. They are also of concern to society as a whole, however, as characteristics of one of the basic elements of the economic system. In the last analysis, the contribution which mineral economics can make as a means of determining and guiding social policy with respect to the production and utilization of mineral resources is perhaps more important than its use as a basis for determining the cost accounting procedure of individual firms. The list of "economic factors peculiar to the industrial minerals" which the authors present is in reality an application of such a broad definition of mineral economics. An inconsistency appears, however, in the inclusion of items 8 and 9 in the list. As this writer sees it, the point in question is: What influences do the characteristics of industrial minerals have on the characteristics and operating procedures of industrial mineral enterprises which are not present in the metallic mineral field? In answering this question with items 8 and 9, Messrs. Ladoo and Stokes do not recognize that there are two distinct types of differences between the two fields of enterprise. There are, on the one hand, important basic economic distinctions due to inherent economic characteristics of industrial minerals which do not pertain to metallic minerals. On the other hand are those characteristics of the industrial mineral enterprises peculiar to them alone, but which are superficial and temporary, in that they may be changed or eliminated at the discretion of the managers of those enterprises. The lack of adequate research and development in industrial mineral production, processing, and marketing (item 8) is not due to an inherent characteristic of industrial minerals. It is true that one may perhaps describe the field of industrial mineral enterprise in terms of such a deficiency, just as one could, until recently, point to a similar lack of research and development in the coal industry; but unless it can be shown that the deficiency has been wholly or partially due to the very nature of industrial minerals themselves it is not an "economic factor peculiar to the industrial minerals" but a temporary characteristic peculiar to the industry. In the writer's opinion, the authors have not demonstrated that the former relationship exists. Similarly, item 9, the "influence of technologic developments," is also not inherently peculiar to industrial minerals. Nowhere in the discussion of this item do the authors mention anything that is not equally applicable to the field of metallic minerals. This is not meant to imply that the specific technologic developments which the authors list are of equal significance in both fields. It does mean that such a statement as, "technological advances together with new consuming areas to provide markets make deposits commercially valuable which once were of no interest" cannot be considered as an argument that technological developments have significance in the field of industrial minerals alone. In considering the problem of stockpiling, the authors note that the stockpiling of nonstrategic materials might be desirable if future wartime needs could exceed domestic production capacity, but dismiss this as hardly adequate to justify such stockpiling. The problem, however, can be stated in broader economic terms, i.e., the real costs (as distinguished from the money costs) of prewar versus wartime production. In other words, it might well be that the labor and capital required to produce a given amount of a certain mineral raw material could be used more efficiently in another industry. In such a case it is obviously advantageous to stockpile the material in prewar times rather than forego the benefits of additional production in another line of endeavor during wartime under conditions which demand the optimum use of all resources, including manpower and capital. To the writer's knowl-

Jan 1, 1951

By A. J. Lanza

IN view of the immense amount of attention that silicosis has received in this country in the past few years, it is timely to review the status of the silicosis problem at present. Who gets silicosis? The individual exposed to the inhalation of free silica dust. The effects upon the individual depend upon the amount of silica inhaled or, in other words, the severity of exposure, rather than upon any special variation or susceptibility among those exposed. A considerable amount of study has been given to determine what may be the role of predisposing causes in the development of silicosis. To mention one instance, at the Picher Clinic careful records were kept of all previous illnesses of the men examined as well as abnormalities present at the time of examination. Examinations of over 27,000 miners were made during the years the clinic was conducted under governmental auspices-a very fair sized sample. The general conclusions from all this work were that the incidence of silicosis is not appreciably influenced by racial, structural, or other inherent qualities; it is influenced by acquired defects-particularly as these affect the lungs. That is to say, the average run of human beings respond similarly to similar exposures to silica dust and those whose lungs are already impaired by tuberculosis or other pulmonary disease acquire silicosis more readily than those with healthy lungs. It may well be, and there is some clinical evidence in support, that negroes acquire silicosis more readily than do whites, but the infection factor has not been so carefully studied among negroes exposed to silica as it has among whites. We know that tubercle infection is more prevalent among negroes than among whites. There may be other factors concerned in the development of silicosis in negroes as compared to whites, but there is not available information upon which to base positive statements. INFECTION AND COMPENSATION Our first ideas about silicosis in this country were derived from early studies in the mining industry where the silica exposure was severe and

Jan 1, 1937

By J. B. Austin, R. L. Rickett

MEASUREMENTS Of the rate of decomposition of austenite at constant temperature are commonly represented by plotting the percentage transformed on linear coordinates against time on either a linear or a logarithmic scale, a method that yields a curve that in shape resembles an integral sign (Fig. 1). A graph of this kind is not always convenient because extrapolation to the beginning or end of the transformation, or even interpolation, may be uncertain unless there are a large number of observations, which seldom happens; furthermore, the degree of consistency of a set of measurements is difficult to judge from such a curve. It is desirable therefore to find some mode of plotting, or even better to find a standard variety of graph paper, that gives a straight line instead of the integral shape. The straight line has many advantages; the number of readings required to fix the position of the curve is greatly reduced, interpolation is easy and rapid, extrapolation can be carried out with greater confidence and, finally, the consistency of the measurements is readily estimated from the scatter of the points. The last advantage is particularly valuable when the data are obtained by direct microscopic examination alone, because they are influenced by the skill of the observer in estimating the relative size of areas, possibly also by undetected inhomogeneity of the specimen. A search for ways of representing the observations as a straight line yielded two methods which are described in this paper. The paper also includes an account of some interesting relations brought to light in applying these methods to the available experimental data. Usually the best way to derive such a method of plotting is to base it on established principles of chemistry and physics, as has been done, for example, for the temperature variation of the equilibrium constant of a chemical reaction. But so little is known of the mechanism of the decomposition of austenite, and so little is available in the way of well established background for changes of this kind, that it is simpler to rely upon purely empirical means. The general plan therefore is to study existing data with a view to finding some function of the direct observations that will

Jan 1, 1938

By R. W. Waterfill

MANY existing ore deposits of valuable metals have been worked out in their upper surface levels and the continued productivity of these mines is dependent on their extension to greater depths in the earth. The maximum depths at present reached are about 6000 to 8000 ft. below the surface, with no evidence of an impoverished ore vein. These mines are widely distributed; some of the best known are in South Africa, Brazil, India and in the western sections of the United States. Among the factors which increase the difficulty of working these mines at increasing depths are hoisting, rock pressure and temperature. The manner and effectiveness with which these problems arc met will, no doubt, determine in a large measure the ultimate depths to which any mine can be profitably worked. The most critical of these three factors at present is the increase in temperature with depth. The high temperature and humidity in many of these mines at present are severely detrimental to the health of the workers and greatly hamper their efficiency. Some have almost reached a condition in which the human system cannot survive. The problems involved in the cooling and ventilation of mines have all been ably analyzed and presented in previous articles. For this reason, only a résumé of conditions affecting the cooling and conditioning of deep and hot mines will be given in this paper before attention is directed to possible methods of improving atmospheric conditions in the working levels. Physiological Effects of Temperature, Humidity and Air Motion Many data on the physiological effects of different atmospheric conditions on the human system have been compiled and published through the combined efforts of the American Society of Heating and Ventilating Engineers, the U. S. Bureau of Mines and U. S. Public Health Service. These data were not primarily developed around the conditions existing in deep mines, but the upper temperature limits of the investigations extend into, and are applicable to, mine atmospheric conditions. While the exact values of the standard comfort conditions, established for persons of such habits as those employed in detecting the different degrees of comfort, might not produce identical effects upon persons inured to

Jan 1, 1929

By E. A. Gulbransen, J. W. Hickman

INTRODUCTION DURING the past two decades considerable progress has been made in the art of manufacturing heater alloys. The conventional iron-chromium-nickel alloys have been improved by the addition of small quantities of other elements. Up to the present time, to our knowledge, there has not appeared a systematic study of these alloys where the newer tools of investigation have been brought to bear on the problem. It is not yet clear what roles the additional elements play in increasing life time in usage. As a first approximation one might guess that elements such as manganese, silicon, zirconium, calcium and aluminum would aid in the formation of a protective film on the alloy surface, thus retarding the oxidation rate and increasing lifetime. If these additional elements do form protective oxides in the outer surface of the oxide film, it may be possible to identify them by means of reflection electron diffraction. It is also possible that the additional elements may not diffuse to the surface but may remain at the interface between the oxide and the metal. Then, too, the major elements in the alloys undoubtedly form oxides which are stratified on the surface. If the minor elements concentrate in a layer in contact with the substrate where they undergo oxidation and if this oxide film offers resistance to the diffusion of iron, chromium and nickel ions, then the lifetime of the heater element might be expected to increase. It is also possible that preferential reduction in the diffusion rates of the several ions may occur to such a degree that oxides may form in the body of the film and on the outer surface which are different from those that would normally form if the additional elements were not present. The use of transmisson electron diffraction may aid us in interpreting these phenomena. Up to the present time all of the factors which influence the lifetime of a given heater element are not definitely known. Among these are: (I) The rate of oxidation of the alloy. This may be dependent upon the composition and the physical state of the alloy. (2) The stability of the structure of the coating which forms. Transitions from one structure to another or solid phase reactions resulting in a change of composition may occur. The tendency of the film to adhere to the substrate when heated and cooled successively will be important. (3) The evaporation of various constituents from the alloy such as the removal of carbon by oxygen in a decarburization reaction. With these possibilities in view, an electron diffraction study of the oxides occurring on six different nickel-chromium alloys was undertaken with the hope that the results of this study could be correlated with oxidation rate studies as determined by means of the vacuum microbalance method1 and with

Jan 1, 1948

By R. Q. Shotts

This paper is a review of recoverable reserves of bituminous coal in the Southern Appalachian area, according to the latest published estimates. A few comparisons are made, some apparent trends are discussed, and some comments are made regarding the limitations of present estimates. The definition of Southern Appalachian area used in this report is somewhat arbitrary. It includes all the bituminous coal deposits of Alabama, Georgia, and Tennessee. All of West Virginia has been excluded. The East Kentucky and Virginia counties included were selected in connection with a literature study the writer made in 1959 of possible coal supply areas for the Tennessee Valley Authority. The selected counties were considered to be the only ones from which TVA might expect to obtain coal. The availability of coal from some of these counties is doubtful, but no other East Kentucky counties were considered more than remote possibilities. With these limitations, the Appalachian area covered is that from which producers of electric power and steel and commercial coal users, located in the Southeastern U. S., may expect to obtain their supplies of coal. Of course, it is recognized that coal from the eastern interior fields is also available to many of these same organizations. RANK AND QUALITY OF THE COALS Practically all the coals in the Southern Appalachian region are of high volatile A bituminous rank. An occasional sample indicates a slightly lower rank, but such samples may be oxidized or otherwise not representative. Some thin beds in Lookout Mountain and Sand Mountain in Alabama and Georgia, are low volatile bituminous coals, but they have not been mined extensively in modern times. There is a possibility that some of the deeper beds along the southeastern edge of the Warrior field of Alabama are near the Low-medium volatile bituminous dividing line. The Sewanee bed and some other minor ones of the Southern Tennessee field, some of the lower beds in Virginia, many beds in Sand and Lookout Mountains in Georgia and Alabama, one or more beds in the Coosa field, possibly some lower beds in the Cahaba field, and most of the beds along the southeastern edge of the Warrior field and the southern end of the Sequatchie anticline of Alabama, are of medium volatile bituminous rank. The quality of the Southern Appalachian coals is highly variable. Some of them, particularly such prevailingly thin ones as the Black Creek bed of Alabama and the Straight Creek bed of Kentucky, are unusually low in mineral matter— probably the lowest in the U. S. With the exception of certain beds and local areas, Alabama and East Kentucky coals probably have as low average ash and sulfur content as can be found in any sizeable coal area in the country. The sulfur content of Southern Appalachian coals is also variable, but few beds are consistently high in sulfur. In Alabama, sulfur generally increases from southeast to northwest across the Warrior field, but this trend is not quite as clear in the other states. A few beds in Northern Tennessee are prevailingly high in sulfur. All Southern Appalachian coals are potential coking coals if they can be prepared to meet chemical requirements. Only a comparatively small part of the medium volatile A bituminous coal, but most of the medium volatile bituminous coal mined is actually used for coking purposes. An estimate of reserves of coking coal under the requirements of present practice, could be compiled comparatively easily, but this probably has never been done. The reserve of coal that can be coked as an ingredient of a suitable blend is probably many times the size of the reserves of coal that will yield suitable blast furnace and foundary coke without blending. WHAT CONSTITUTES ECONOMICALLY RECOVERABLE COAL RESERVES? When one first realizes the vast extent of the coal-bearing rocks in the Southern Appalachian area, (see Fig. 1) the thought is likely to occur that the supply of coal is inexhaustible. This is particularly true on realizing that in some of the basins of thicker coal-

Jan 1, 1962

At a meeting of the Board of Directors, held Jan. 21, 1916, the following resolution was adopted: Resolved, that this Board has learned with indignation and sorrow of the unprovoked and brutal murder of 18 American citizens on January 10, in the State of Chihuahua, Mexico, and laments especially the death of Messrs. C. R. Watson, C. A. Pringle, H. C. Hase, and W. J. Wallace, who were members of the American Institute of Mining Engineers. As these men and their companies were engaged, in the lawful prosecution of their work, we trust that nothing will be allowed to prevent or delay appropriate action by our Government concerning the outrage by which they lost their lives;

Jan 3, 1916

By J. F. Martin, L. M. Melnick, R. Rapp, R. C. Takacs

Recent studies on the determination of hydrogen in steel have shown that the hot-extraction method for removing hydrogen from a solid sample is preferable to its removal from a molten sample by vacuum fusion or by fusion in vacuum with tin. A number of techniques are available, however, for determining the hydrogen so extracted. They include: thermal conductivity, gas chromatography, pressure measurement before and after catalytic oxidation of the hydrogen to water and removal of the water, and pressure measurement before and after diffusion of the hydrogen through a palladium membrane. These techniques have been evaluated on the basis of initial cost, maintenance, speed and accuracy of analysis, and applicable concentration range. The results of this study showed that the palladium-membrane technique is best suited for routine use. FOR some time investigators have been concerned with the origin, form, and effect of hydrogen in steel. In such stdies', the analysis for hydrogen constitutes one of the most important phases. It is quite apparent that the results for hydrogen concentrations in a given steel are dependent on the method of obtaining the sample, storage of the sample until analysis, preparation of the sample, and analysis of the sample, including all the facets inherent in the calibration and operation of an apparatus for gas analysis. There are a number of means available for determining hydrogen. This is a critical study of some of the more common techniques in use today. In most conventional melting and casting methods, hydrogen concentrations of 4 to 6 parts per million (ppm) in steel are quite common. Because of the undesirable effects of hydrogen on steel there has been increased use of techniques such as vacuum melting,' vacuum casting, and ladle-to-ladle stream degassing, which lower the hydrogen content to levels on the order of 1 to 2 ppm. Therefore, the method used for determining hydrogen in steel must be sensitive and precise. In any analytical procedure for gases in metals there are two distinct operations—the extraction of the gas from the metal and the analysis of the extracted gas. To extract the gas from the steel, three methods have been employed: 1) fusion of the sample with graphite at high temperature; 2) fusion with a flux, such as tin, at a lower temperature; and 3) extraction of the hydrogen from the solid sample at a temperature below the melting point of the steel. Fusion with graphite is the least-acceptable method. The blank in this method is higher and more variable than in either of the other two methods. The hydrogen fraction of the total gas composition usually is between 10 and 50 pct; thus, a larger analytical error is possible. The vacuum-tin fusion4 extraction of hydrogen is probably the most rapid method in use today; the extraction time is usually about 10 min. However, with this system a bake-out of the freshly charged tin for 2 hr is necessary and a change of crucible and a charge of fresh tin are required after each day of operation whether one or thirty samples have been analyzed. In addition, frequent checks of blank rates are required since CO and Na are continually being given up by the steel samples dissolved in the tin bath. The composition of the gas in this method lends itself readily to analysis; although the hydroge concentration may fall to as low as 50 pct, more often it is above 90 pct, thus allowing a more precise analysis (because of less interference from other gases). In 1940 ewell' published the hot-extraction method for extracting hydrogen from the solid sample, comparing analysis for hydrogen extracted at 600°C with similar analysis for the gas extracted at 1700°C by fusion with graphite. Good agreement for hydrogen was obtained between these two methods, provided sufficient time was allowed for extraction at the lower temperature. carsone obtained good results in his comparison of this hot-extraction method with vacuum-tin fusion. Subsequent work by Geller and sun7 and Hill and ohnson' has shown that steel samples should be heated to at least 800°C to effect the release not only of the diffusible hydrogen but also of the "residual" hydrogen that may be present as methane. Since the rate of evolution of hydrogene9l0 depends on such factors as sample size and composition, thermal history, and extent of cold work, a fixed extraction time is not possible. Extraction times of 30 min are normal, but 2 hr are not unusual. Induction or resistance heating may be used in the hot-extraction method. With resistance heating the

Jan 1, 1964

By D. E. Norquist, J. E. Moeller

The results of wear on marked balls, 4, 31/2, 3, and 2 in. diam are given. All balls were forged steel of practically the same chemical analysis and hardness. The results indicate that balls in a given mill for a given length of time will have equal diameter losses, regardless of size.

Jan 1, 1950

By John W. Bell

In the introduction to an excellent pamphlet, John Gross' makes the following statements: Although marked progress has been made along mechanical lines, the theory and conception of underlying principles have not advanced so rapidly. This lack of advance in theory may be attributed to the unfortunate situation resulting from the controversy as to whether the Rittinger or Kick law is applicable to crushing. Many pages of the technical literature are burdened with theoretical discussions in favor of one or the other of these laws, which have tended to cloud rather than to clear the atmosphere. Realizing the situation, the Milling Committee of the American Institute of Mining and Metallurgical Engineers, through its secretary, E. A. Hersam, studied the milling industry and, because of the apparently hopeless lack of agreement in the Kick versus Rittinger dispute (5, 13, 14, 16, 18. 19. 21, 22, 23, 24, 30, 34). concluded that a foundation lor the theory of crushing was of primary importance. The numbers in the paragraph quoted refer to papers listed by Mr. Gross in his Bibliography on Crushing and Grinding.I One is obliged to infer that these papers show "hopeless lack of agreement in the Kick versus Rittinger dispute." No. 22 is a paper by Arthur 0. Gates2 and No. 23 is one by the writer.3 Employing the subject matter contained in papers Nos. 22 and 232,3 the writer will show that their authors formulated identical conclusions, based solely on experimental evidence. Exactly the same defect in the Stadler hypothesis was described in each of the two papers, although entirely different experimental methods were employed in uncovering it. Both of the authors, independently, formulated the conclusion that Rittinger's was a true hypothesis and Stadler's false. The evidence in a third paper4 will be employed to prove that Stadler's hypothesis, when examined experimentally, is worthless. Stadler's Hypothesis Worthless It is the writer's opinion that the evidence available in 1915 and the corroborating evidence in 1916 was amply sufficient to eliminate the need for any further consideration of Stadler's hypothesis. Certainly the evidence produced in 1918 dealt this hypothesis its coup de grace. It follows, therefore, that in the year 1918 there was only one credible hypothesis left—the Rittinger hypothesis. Gates' Opinion What information is available in Mr. Gates' paper?2 His conclusions are not consecutively summarized, none the less they are perfectly clear. On page 876, Gates says, and it is a very significant utterance: But my results show, among other things. that many more of Stadler's energy units are obtained per foot-pound-applied in coarse than in finc crushing. This suggests a doubt as to the correctness of his unit, since one would expect a foot-pound-applied to produce the same number of "energy units," whether the feed and resulting product were coarse or fine. When Rittinger's theory is applied, the number of mesh-tons (my unit of surface produced) is

Jan 1, 1943

By John W. Bell

In the introduction to an excellent pamphlet, John Gross' makes the following statements: Although marked progress has been made along mechanical lines, the theory and conception of underlying principles have not advanced so rapidly. This lack of advance in theory may be attributed to the unfortunate situation resulting from the controversy as to whether the Rittinger or Kick law is applicable to crushing. Many pages of the technical literature are burdened with theoretical discussions in favor of one or the other of these laws, which have tended to cloud rather than to clear the atmosphere. Realizing the situation, the Milling Committee of the American Institute of Mining and Metallurgical Engineers, through its secretary, E. A. Hersam, studied the milling industry and, because of the apparently hopeless lack of agreement in the Kick versus Rittinger dispute (5, 13, 14, 16, 18. 19. 21, 22, 23, 24, 30, 34). concluded that a foundation lor the theory of crushing was of primary importance. The numbers in the paragraph quoted refer to papers listed by Mr. Gross in his Bibliography on Crushing and Grinding.I One is obliged to infer that these papers show "hopeless lack of agreement in the Kick versus Rittinger dispute." No. 22 is a paper by Arthur 0. Gates2 and No. 23 is one by the writer.3 Employing the subject matter contained in papers Nos. 22 and 232,3 the writer will show that their authors formulated identical conclusions, based solely on experimental evidence. Exactly the same defect in the Stadler hypothesis was described in each of the two papers, although entirely different experimental methods were employed in uncovering it. Both of the authors, independently, formulated the conclusion that Rittinger's was a true hypothesis and Stadler's false. The evidence in a third paper4 will be employed to prove that Stadler's hypothesis, when examined experimentally, is worthless. Stadler's Hypothesis Worthless It is the writer's opinion that the evidence available in 1915 and the corroborating evidence in 1916 was amply sufficient to eliminate the need for any further consideration of Stadler's hypothesis. Certainly the evidence produced in 1918 dealt this hypothesis its coup de grace. It follows, therefore, that in the year 1918 there was only one credible hypothesis left—the Rittinger hypothesis. Gates' Opinion What information is available in Mr. Gates' paper?2 His conclusions are not consecutively summarized, none the less they are perfectly clear. On page 876, Gates says, and it is a very significant utterance: But my results show, among other things. that many more of Stadler's energy units are obtained per foot-pound-applied in coarse than in finc crushing. This suggests a doubt as to the correctness of his unit, since one would expect a foot-pound-applied to produce the same number of "energy units," whether the feed and resulting product were coarse or fine. When Rittinger's theory is applied, the number of mesh-tons (my unit of surface produced) is

Jan 1, 1943