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MANY are the salts produced. by Nature in various regions and parts of the world, as Pliny shows in his History. Likewise, many are the differences among things that are salty and from which salt can be extracted, as, for instance, all the lyes from any kind of ashes and the urine of all animals. But because these are not things that give men the useful elements necessary to life, I shall omit speaking of them in detail with the exception of some of the more notable ones, and I shall tell you that I find that men proceed in only two ways in order to have a sufficiency for their needs. One is that of extracting it from the salty waters of the sea itself, or from springs, with a certain technique [34v] adapted to the places, either by congealing or by evaporation; and the other is that of mining it from the earth. The latter salt is clear and beautiful, and it is mined from mountains, already made by Nature in the form of stone without the aid of art. All these salts have more or less efficacy* according to the fineness or coarseness of their earthy elemental mixture, and according to the provinces and places where they are found generated. All are of an earthy

Jan 1, 1942

By W. H. Adams

During the years when Americans were most active in investigations of the many substances containing nitrogen or ammonia, viz.: 1869 to 1875, my connection with certain chemical industries led me to experiments in the direction of the recovery of wastes from coal-gases. I take from my notes such memoranda as I think will be of interest, in the hope that some benefit may be derived therefrom by engineers at present attempting to utilize the waste products from coke-oven and blast-furnace gases. An examination of the conditions governing the manufacture of gas along the Atlantic seaboard, and an intimate knowledge of the mine-products used by the different large works, naturally led me at first to consider the well-known foreign methods of concentrating the available soluble salts in a modicum of water. The result was sufficiently promising to warrant a full line of experiments. At that time, no attention seemed to have been paid to the values of " gas-liquors." Nearly every gas-works in the United States wasted its wash-water in the sewers. The nitrogen in bituminous coals varies in quantity from 0.75 to 1.50 per cent. of the total weight. In the process of distillation in

Jan 1, 1887

By Max W. Bowen, A. J. Weinig

The important part that dissolved oxygen plays in the cyanide treatment of gold and silver ores is commonly recognized by most metallurgists and mill men. But heretofore there has been no simple method on which the mill man could rely for determining the amount of oxygen in the various mill solutions. A few methods are adaptable to the laboratory, such as the gasometric1 determination by actually measuring the oxygen, Winkler's2 iodometric method, and Schutzenberger's3 method, which depends on the reducing action of sodium hyposulfite on a blue solution of indigo carmine; but these are not readily adaptable to the needs of the mill man and cannot be applied to cyanide solutions without modification. The gasometric method is the most accurate but it takes too long to complete a determination. White's4 method (a colorimetric method that depends on the degree of coloration imparted to a solution of pyro-gallic acid in the presence of caustic soda) although much more rapid than any of the methods named, often gives misleading results on account of grading of colors of different solutions, which nearly always contain various kinds of salts. The method herein described was devised for the use of the mill man, the aim being to develop a simple, practical, accurate method. It is a modification of the Schutzenberger method and depends on the reducing

Jan 1, 1925

By D. O. Ehrenburg

DURING the earlier period of electrical prospecting, the search for orebodies was by far the most important application of this method of geophysical prospecting. In the past few years, however, increasing attention has been paid to the possibilities of this method in the investigation of subsurface structures. Not only have fault zones been located, but attempts have been made to determine the depth to certain strata and thus contouring on some bed which proves to be a good "electrical marker." Many workers have published the results of field tests showing how their particular interpretations have agreed with the actual field conditions, but very few have stated their method of interpretation. Weaver, Hummel and Stefanesco and Schlumberger1 have given a more theoretical discussion of the resistivity methods. Hummel and Stefanesco and Schlumberger have published mathematical solutions for the flow of electricity in a medium involving four layers. In this paper the authors present a solution for the flow of electricity in a medium of any number of horizontal strata. By means of this solution, curves showing the relationship between the apparent resistivity and the electrode spacing can be computed for ideal cases.

Jan 1, 1931

By G. V. Sullivan, B. E. Davis, T. O. Llewellyn

The Bureau of Mines, US Department of the Interior, conducted studies to recover phosphate from four dolomitic southern Florida deposits not currently mined. The samples contained 5.8-10.2% P205 and 1.7-4.8% MgO. Chemical analyses of sized fractions indicated that no pebble concentrate, +1.2 mm (+14 mesh) could be produced from these samples. A scheme was developed that consisted of desliming, grinding, scrubbing, and redesliming the ore to produce a flotation feed. Conventional one-step fatty acid fuel oil batch flotation tests on the samples resulted in concentrates containing 29.0-31.3% P205 at flotation recoveries ranging from 72.4 to 96.1% of the flotation feed. The MgO content of the concentrates ranged from 0.47 to 1.36%. Continuous flotation of the Manatee No. 2 sample indicated that commercial-grade phosphate concentrates analyzing 31.3% P205 and 0.55% MgO could be produced with a flotation recovery of 89.9%. The MgO content of concentrates obtained from the Manatee No. 1 and Hardee samples was 1.20 -1.36 %, respectively. Leaching with aqueous SO2 reduced the MgO content of these phosphate concentrates to 0.5 and 0.8%, but with a concomitant loss in phosphate recovery of about 10%.

Jan 1, 1985

By Irving Fatt, R. M. Weinbrandt

Efforts have been made for many years to observe pore structure of sedimentary rocks on a microscopic scale. A better description of the pore structure in reservoir rock would aid in the development of relations between flow through tube network models and flow in consolidated reservoir rock. The unique qualities of the scanning electron miscroscope (SEM) make it the ideal tool to use in a study of pore structure. Previous methods of studying pore structure included plastic casts of pore space and optical microscopy.l-7 There is now available a new method to observe three-dimensional flow channels in reservoir rock: a scanning electron microscope having variable magnification from X20 to X20,000 and approximately 1000 times the depth of focus of the conventional light microscopes. This microscope also can obtain stereoscopic images and can measure and diagram flow channels so that it is possible to construct a network of tubes that will model consolidated reservoir rock. THEORY OF THE SCANNING ELECTRON MICROSCOPE The scanning electron microscope (SEM) functions by projecting a beam of electrons through magnetic focusing lenses at a specimen and recording secondary electrons excited by the primary beam. The amount of secondary electron emission portrays the topography of the specimen because more secondary electrons are emitted from high points than from low points. A schematic of the SEM is shown in Fig. 1. The property of the SEM that is of most importance in this study is its great depth of focus. The depth of focus results from using electrons

Jan 1, 1970

By E. Gybbon Spilsbury

It is not my purpose in this paper to describe all the different contrivances which have been devised, during the last quarter of a century, for the purpose of Iessening the expense of mining and tunnelling operations; I wish merely to call your attention to the crying want of the Western miners for some cheap and effective machine, capable of economizing on the heavy item of hand-drilling, and to enumerate a few of the latest improvements which have been made in machines of this class. This necessity for the introduction of some kind of labor-saving machinery in mining, especially in the West, begins to make itself felt more imperatively every day. No branch of industry has remained so conservative to the old customs and systems of working, as has mining; and yet no branch is so entirely dependent on economical working for a successful issue; and in very few is the proportion of cost of hand-labor to profits obtained so preponderantly heavy. Perhaps the chief reason for this seeming apathy towards progress in this direction arises from the fact that nearly all mining operations, especially in this country, are carried on in regions more or less remote from the great centres of civilization, thereby rendering the carriage and erection of machinery extremely difficult and expensive. Another reason, however, exists in the fact that a large number of men in charge of mining operations are greatly prejudiced against the introduction of machinery underground, from the idea that it cannot be made to adapt itself to the various positions and

By D. A. Dahlstrom

THE necessity for slime elimination from valuable mineral and coal products has become increasingly significant within the past 5 years.1,2 Most of the mechanized mining and present beneficiation methods have resulted in larger tonnages of extreme fines, silts, and clay, commonly called slimes, processed by the preparation plant. Economics in turn have forced the plant operator constantly to lower the bottom size of effective beneficiation, necessitating an almost complete recovery of valuable solids regardless of particle size. When these important factors are considered, the need for an efficient slime removal method for fine solids becomes self-evident. Ordinarily slimes have been classified as ranging from 75 microns, or 200 mesh, down to colloidal dimensions of less than one micron. At the same time there is general agreement that the most troublesome slimes are primarily clays, silts and extreme fines, so that the actual top size may be placed at approximately 30 to 40 microns. This immediately restricts any desliming operation to classification, as screening or other methods would be both uneconomical and grossly inefficient at such dimensions. The liquid-solid cyclone has been recognized as one of the most efficient fine size classifiers available to the mining industry. Applications of cyclones to thickening, high efficiency solid recovery, degritting,

Jan 1, 1952

By R. H. Johnson

The Manual of the Oil and Gas Industry, under the Revenue Act of 1918, published by the Treasury Department for the guidance of oil companies in preparing their estimates of future recoverable oil for the purpose of calculating depletion, gives the first large public collection of comparative decline curves for the whole country. It is a matter of both scientific and practical interest to so arrange these data that the pools can be readily compared. There are certain difficulties in such a comparison, however: (1) The economic limit varies from 50 to 2000 bbl. a year in different pools taken. (2) Because of this variation in economic limit, the range of data shown makes comparison possible only for wells of intermediate size. In order to be as inclusive as possible, I have taken as an expression of the rate of decline the amount of oil produced in the period during which a well drops from 3000 to 2000 bbl. a year. No period of smaller production could be used because of the high economic limit in California; and no period of larger production and yet include the small well areas of the Appalachian. As it is, the Lima-Indiana wells are excluded. In a few instances, curves were extrapolated to obtain the reading, where the curve seemed regular enough to warrant it. In general, the amount of oil, in barrels, produced while a well declined from 3000 bbl. to 2000 bbl. a year is shown in Table 1.

Jan 1, 1921

By Mack H. Shumate

1 Raw coal from Truax-Traer Coal Co.'s Burning Star Slope mine, Jackson County, Ill., is brought to the surface by the new 42-in. slope belt haulage conveyor at the rate of 850 tph. The loading system shown above employs four storage tracks, two tail tracks for loading, and four 25-hp hoists, operating in pairs, and coupled to two dolly cars to move the trains of cars through the tipple. The system has a capacity for loading 1800 tph. One operator is needed to load on each of two shifts. A third man working for a few hours on night shift sets up for the morning cycle. Railroad crews bring in empties placing them in the storage yard, twenty cars to the track. Trains of empties are pulled through to the tail track and loaded on the return; hoists at opposite ends pull the trains in each direction. [ ] 2 Pairs of hoist drums are interconnected electric- ally by a Trench lay cable buried between the tracks. When one hoist operates moving the cars, the tail hoist idles with brake released. The operator, situated in the tipple over the cars, views the storage yard at the end of the first shift (left). When returning loaded cars to yard, four or five cars are held on the dolly to couple the next string of empties. Empties are ready for loading on the tail track (right). Differing from a gravity system in which empty and load tracks are on a slight grade, this system is designed for 80 railroad cars for a two-shift operation and one rail service per day.

Jan 6, 1962

By Mark Malamphy

DURING colonial times, Brazil was famous for the richness of her alluvial gold deposits. Paul Ferrand has estimated that the gold produced during the period from 1700 to 1820 was the equivalent of some 64 million pounds sterling. Since that time, most of the more prolific alluvial deposits have been exhausted. A few gold mines are still func-tioning, notably the Morro Velho mine, which is one of the deepest mines in the world. Today, the gold production of Brazil is insignificant when compared with world figures, but there are still many gold-bearing regions and it is probable that in at least some of them profitable returns would result from an exploitation program taking advantage of all the most modern innovations in gold mining and ore treatment on a large scale. In order to demonstrate the value of some of these abandoned pros-pects and stir up interest in increasing the national gold production, the government has stimulated research. Experimental plants have been and are being established in various places, and tests on large quantities of ores are being carried out on a semicommercial basis. The Geological Survey of the State of Minas Geraes is very active in this line and the Federal Institution is also showing an increased interest in the matter.

Jan 1, 1934

By B. Ladanyi, B. Hoyaux

A first requirement for assessing the safety of a rock slope, either artificial or natural, particularly if the rock behaves in an elastic-brittle manner, is a propw knowledge of the distribution of stresses within the slope and their development with time and advancement of workings. There are a uumber of different methods that can be used, in principle, for obtaining this information, such as (1) stress measurement in situ, (2) photoelasticity,1 (3) analytical methods, and (4) numerical methods. In cases where the stress distribution cannot be obtained by classical analytical methods, as in the one considered herein, either photoelasticity or numerical methods are norrnally used. However, actually, due to the rapid development of high-speed computers, increasing preference is given to the numerical methods. Among the latter, the most successful ones, to date, for determining the stress distribution in slopes have been (1) the finite difference method,2-4 (2) the lumped parameter method,5 and (3) the finite element rnethod.6 However, for determining gravity stresses in a natural rock slope, only the finite difference method has been used until now.7,8 A solution of the same problem by the finite element method will be shown here in which a particular reference is given to the development of tensile fracture zones within the slope. FINITE ELEMENT METHOD The stress analysis using the finite element method originates from an extension of the matrix analysis of structures.9 It consists in decomposing a continuous medium, assumed herein to be homogeneous and isotropic,

Jan 1, 1972

By E. H. Lovitt, A. C. Skerl

After nine years of continuous operation it is a good idea to take stock of the geological concepts that guide the working of a mine. This is a welcome opportunity to discuss the Lovitt gold mine, which has been a challenge in both the geological and operational fields. The occurrence belongs to the extensive group of epithermal gold-silver deposits once worked so vigorously in the western states, Hungary, and New Zealand and still producing in Central America and the Philippines. These deposits are characterized by a relatively shallow vertical range up to 2000 ft, and often much less, and by bonanza orebodies of even more limited range. The area in which they occur is frequently widespread, so that exploration must be directed along and across the strike of known favorable structures in search of repetitions.

Jan 9, 1958

Striving to do a better job of ad- ministering the letter and spirit of the Federal Coal Mine Health and Safety Act of 1969, the Interior Department recently invited criticism-and got it. The criticisms were voiced on July 1 and 2 at the first of a series of public meetings being held by the Office of Hearings and Appeals at the Department's behest. Later meetings, at which all interested parties are invited to comment, are to be announced in the press and the Federal Register. Persons wishing to participate in the meetings should contact the Director, Office of Hearings and Appeals, 1015 Wilson Blvd., Arlington, Va. 22203. At the first Hearing, USBM Director Elburt F. Osborn outlined the progress his agency has made to date in implementing the law on three fronts: enforcement, education and research. Since the Health and Safety Act became law on December 30. 1969, he said, the Bureau's force of inspectors has grown from a mere 300 to almost 1100, while mine inspections have increased from 10,265 in 1970 to 11,021 for the first six months of 1971. On the educational front. Osborn said, the Bureau now has some 60 instructors who have trained about 50,000 miners in safety procedures since March 30. 1971. Classes at the new Federal Mine Safety Academy for both government and industry personnel begin on September 1, 1971. he added. Health and safety re- search, meanwhile, has been allot- ted $20.1 million for the 1971 Fiscal Year. Of this, $8.1 million is assigned to the Bureau and $12.3 million to contracts with universities and private companies. Admittedly, Osborn said, the mine fatality rate is still unacceptable, hut it was lower in the first half of 1971 than ever before---0.73 per million man hours and 0.31 per million tons of coal.

Jan 1, 1971

By Arthur Knapp

OIL-WELL depletion curves, to be of value, should show when a well or lease may no longer be operated at a profit. The difference, at any time, between the total expenditures and the total income of a lease or well may be called the lease status. Plotting this lease status against time will give a curve subject to more accurate and different interpretations than the barrels-time curves. According to the hypothetical barrels-time curves shown in Fig. 1, well A, at the end of 16 mo., is producing twice as much oil as well B and will continue to produce for another year whereas well B will cease producing in about 6 months. DATA FOR LEASE STATUS-TIME OR DOLLARS-TIME CURVE TIME LEASE MONTHS STATUS Lease purchased for $3000 0 -$ 3,000 No expenses chargeable to lease for 3 mo 2 - 3,000 Well A is started; cost of drilling for month is $16,000 3 - 19,000 Well is completed at additional cost of $10,000 4 - 29,000 Well A is brought in and flows 10,000 bbl. first month (see Fig. 1). Necessary to invest in tanks, boilers, pipe lines, etc.: difference between expenditures and receipts gives profit for month of $5,000 5 - 24,000 Investment is small, cost of operating well A is small, so profits are $15,000 6 - 9,000 Well ceases to flow so there is additional investment for pumping equipment and additional operating expense; net earnings from 6,000 bbl. of oil produced is $4,000.... 7 - 5,000 Lease operation now becomes normal and curve becomes smooth 8 - 500 9 2,000 10 4,500 11 6,000 12 7,700 13 8,700 14 9,000 15 9,500 16 10,000

Jan 1, 1921

By I. N. Zavarine

THE present paper is a continuation of the work on the relationship between the magnetic and the phase transformations in carbon steels during quenching. An account was given by the author in a previous paper It of an investigation of this relationship during a continuous quench. The experimental difficulties then encountered prevented a conclusive proof of the existence or absence of such a relationship. The conclusions of the previous paper were derived indirectly. The present paper deals with the same problem, but the method of attack is modified. The technique developed by Davenport and Bain2 in their well-known study of austenite transformation at subcritical temperature was adopted in the present investigation. They have shown that the austenite to martensite transformation can be caused to proceed at a relatively slow rate by quenching steels into a hot metal bath. Slowing down of the rate of transformation, together with an observation by Lewis3 that a eutectoid steel can be preserved in the nonmagnetic state by such quench-ing, pointed out a possibility of a study of both transformations under more favorable conditions than previously described. The preliminary steps were connected with the technique of the hot bath quench. To study this phase of the present work a modification of the apparatus previously describe1 was used. The modification con-sisted in the use of a hot quenching bath instead of brine, and in fixing the secondary and the primary coils of the apparatus in a stationary position in and around the bath. Tubular specimens, as in the previous investiga-tion, were heated in a suitable furnace to a temperature in the austenitic.

Jan 1, 1935

By R. B. Lincoln

THE function of a pyrometer protecting tube is to maintain an atmosphere about the thermocouple most favorable to its continued accuracy and long life, and at the same time permit the weld of the couple to attain the full temperature of the area or object being measured. In addition to protecting the thermocouple from the chemical or alloying effects of the products of combustion or bath being measured, the tube must also protect the couple from mechanical injury. The conditions met in practice vary so much that no one material is suitable for all applications. The usefulness as well as the expense of maintenance of a pyrometer system are influenced greatly by a choice of the most suitable protecting tube. The tube must protect the couple without itself becoming too great an expense item. The protecting tube should have the following qualities: (1) A melting point well above the highest temperature to be encountered. (2) Sufficient strength through the entire range of temperatures to hold up its own weight and resist such shock and jar as are unavoidable. (3) It must be impervious to the atmosphere or bath to which it will be subject. (4) It must not give off any vapor injurious to the couple. (5) It must not form any oxides fusible below the highest temperature to be measured. The proper location of the tube in the furnace is almost as important as the choice of material. The tube must be placed as near to the work to be heated .as possible. It must be kept out of the direct path of flame, both because that would give too high temperature readings and because partly burned fuel will destroy the tube faster than the quiet products of combustion.

Jan 9, 1919

By R. S. Lewis

IN a recent study1 of the evolution of engineering education 1870 was taken as the initial point, as it is said to mark the transition from the poineer era in American engineering education to an era of rapid growth and consistent development. Prior to the founding of Rensselaer Polytechnic Institute in 1824, West Point Military Academy was the principal source of formal engineering training. In 1849 Rensselaer revised its program on the model of the leading French technical schools. Lawrence Scientific School was estab-lished at Harvard and Sheffield Scientific School at Yale in 1847. The University of Michigan pioneered in en-gineering instruction in the West, offering its first course in 1853 and awarding its first degree in 1860. Other important steps in -the progress of engineering education were the founding of Columbia School of' Mines in 1864, the opening of Massachusetts Institute of Technology in 1865, and the founding of Cornell Uni-versity and the Thayer School of Civil Engineering at Dartmouth in 1867. From its organization in 1852 until 1871 the Ameri-can Society of Civil Engineers was virtually the only national society of engineers. In 1871 the American Institute of-Mining and Metallurgical Engineers was founded, to be followed later by the Mechanical En-gineers in 1880 and the Electrical Engineers in 1884. This expansion and diversification of the engineering profession was paralleled in the colleges, and by 1885 the plan of different curricula in the major branches of engineering was soundly established.

Jan 7, 1927

By Augustus Locke

Two Opposed Interpretations of the Tonopuh Structure.—The important geological publications concerning the Tonopah min-ing-district are those of Spurrl aud of Burgess.² In these publications are presented fundamental differences of interpretation, which are the more interesting because both authorities have had ample opportunity for observation, and because both are geologists of proved ability. I was vastly puzzled to know which had the better of it, and in order that I might reach a conclusion in my own mind, I recently spent some time in the district going over the physical evidence. Surprising as it may seem, this evidence looks conclusive. A review of it will, I believe, be of interest to those who are familiar with the previous publications. The general geological features of Tonopah are shown in Fig. 1, and the differences of interpretation referred to are outlined in the accompanying notes. Brieflyj Burgees regards the various rocks as flows, lying in the order of their deposition. Spurr regards them in part as flows, and in part as flat-lying intrusives. The disagreement, then, concerns the rocks regarded on the one hand as intrusives, and, on the other hand, as flows. These rocks are chiefly the so-called calcitic andesitc, the upper rhyolite, and the lower rhyolite. Economic Importance of the Question of Interpretation.—The economic importance of the question of interpretation is, of course, limited to its bearing on the probable distribution of

Jan 1, 1913

By Gerald Edmunds

THE development of "fiber" or preferred orientations, during the plastic deformation of metals, and the relation of such structures to the anisotropic characteristics of worked metals has become a subject of common knowledge among metallurgists. Very little has been published, however, relative to variations existent throughout the cross-sections of rolled strips,1 and the influence that such variations may have. This paper presents such a study on a rolled zinc alloy.2 The significance of small differences in surface structure is shown in relation to bending properties. Experience with zinc and its alloys has shown that the outer radius of the bend, which is subject to tensile deformation, is the common region of failure. In considering relations of structural characteristics to bending properties it will suffice, therefore, to consider the ease and possible extent of tensile deformation resulting from various orientations. It is necessary in this connection to assume that on the average the individual crystals of a polycrystalline material act substantially as if their movements were unobstructed by the surrounding grains. This assumption is not strictly valid, but the error involved is unlikely to affect seriously the qualitative conclusions derived from its use. The mechanism of the plastic deformation of zinc crystals has been described by Mark, Polanyi and Schmid3 and by Mathewson and Phillips,4 and is regarded as ' being accomplished by block movements or

Jan 1, 1931