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W. Morton Webb, Germiston, Transvaal, South Africa (communication to the Secretary*):—The experience of Mr. Boeh-mer in the Leadville district and his reputation as an engineer assure the interest of anything he may write on the ore-bodies of that district; and all engineers who have operated in Leadville will agree that the theory of the origin of the Leadville deposits, as given by Mr. Emmons in his famous monograph, does not adequately explain the genesis of all the deposits. The solutiou of the problem does not, however, appear to be quite so simple as Mr. Boehmer would make it; and the advance pamphlet issued by the U. S. Geological Survey, pending the completion of the main report, shows that there is still much ground for controversy. No doubt the later eruptive0 had a greater influence on the deposition of the ore-bodies than was thought at the time of the first investigation by the Survey; but it has always appeared to me that the influence exerted by these dikes mas more in the nature of a physical than a chemical one. The weight of evidence in recent years is mostly in the direction of ascension rather than lateral secretion; and one of the strongest evidences is the fact that most of the ore-bodies lie under one of the comparatively impervious layers which help to make up the structure of these hills.

Jan 1, 1911

By Sumner M. Anderson

Any discussion of outside support to Latin American mineral industries must concede at once the pre-eminent role of U. S. industry and business. American capital has developed the great copper resources of Chile and Peru, the lead-zinc of Peru and Mexico, the bauxite of Surinam and Jamaica, the petroleum and iron ore of Venezuela. American consumers have provided the market for their products. U. S. companies operating south of the border have trained Latin American geologists, engineers, chemists, and skilled labor-including metal, mineral, and fuel technicians-to new and greater competence. The industrial demands of World War II drastically altered world economics and concepts of U. S. foreign mineral requirements. In this country discovery of vital mineral resources fell far behind the alarming depletion rates, and there was new appreciation of the actual and potential importance of the world's less extensively explored areas. During the war and afterward, the task of supplying the nation's mineral requirements became greater than private industry could carry alone, and the Government assumed a position of continuing support.

Jan 11, 1958

Mother Earth has had a long life extending over two billion years, during which time she has changed from a mass of incandescent gases to her present form, exhibiting a density stratification from the extremely tenuous gases of the stratosphere to the heavy central nickeliron core. Man is now mining all the principal divisions of Mother Earth except the centrosphere. Nitrogen, oxygen, neon, and other rarer gases are being recovered from the air; magnesium, bromium, potash, borates, and other salts from lakes and seas; brines, medicinal mineral waters, and great quantities of water for domestic and industrial uses from surface and subsurface reservoirs; and, from the rocky crust, many minerals and fuels for our present industrial civilization as well as plants and animals for food and shelter. Productivity of soil is influenced both positively and negatively by man. There is some cause to bewail what may be considered a wasteful influence of men on soil. The general situation is bad in spots but not hopeless. The passing of large areas of fertile land in some areas is merely to be noted and not to be mourned. These lands could not have been used without decrease in their fertility. The productivity factor is affected by human activities. Many soils in the eastern and southern states are far richer and more productive now than they were at any previous time. Arctic soils are not productive

Jan 1, 1950

By P. P. Gregory

NATURAL petroleum gas occurring in the oil-bearing reservoirs is found to exist either as free gas associated with the oil and/or in solution in the oil. In some virgin fields practically no free gas is encountered under the reservoir conditions of pressure and temperature, although in other fields a considerable section of the ``pay" horizon is occupied by free gas. In other words, a given oil field may or may not have a gas cap before the exploitation takes place. However, when the reservoir pressure is reduced to a point below the critical saturation pressure by withdrawals of fluids from the producing formation, the gas dissolved in the oil inevitably begins to come out of solution and becomes free gas. Under the con-trolled methods of production and drilling, a portion of this gas is pro-duced with the oil to the surface and a portion of it remains within the reservoir to accumulate at higher structural levels toward which it migrates by virtue of its low specific gravity. The rate of growth of a gas cap in a-given structure depends primarily upon the rate of decline in the reservoir pressure. If the rate of pressure decline is rapid, the gas cap likewise will grog rapidly. On the other hand, shrinkage in the gas-cap area was noted in some fields in which reservoir pressures were increasing.

Jan 1, 1938

FOLLOWING- the major explosion disaster in the Orient No. 2 mine of the Chicago, Wilmington and Franklin Coal Co., West Frankfort, Ill., on December 21, 1951, resulting in the death of 119 miners, an investigation was made by the U. S. Bureau of Mines under the direction of J. J. Forbes, Bureau director. The subsequent report concluded that the disaster. was caused by the emergence of a-large body of explosive gas from an abandoned area and simultaneous short circuiting of the ventilating current; the gas was ignited by an electric arc from nonpermissible electrical equipment and the flame was propagated throughout a large part of the affected area by coal dust and possibly by gas from other worked-out and abandoned areas. An immediate repercussion of the disaster was the opening of hearings by the. Senate Labor and Public Welfare Subcommittee on the Neely Mine Inspection Bill (S. 1310, introduced April 11, 1951) which would give federal coal-mine inspectors power to enforce safety recommendations by ordering the withdrawal of all employees where conditions constitute an imminent danger to their safety. Two days of testimony, January 24 and 25, disclosed that coal operators were not in agreement on the bill, although John L. Lewis, speaking for the UMWA, and J. J. Forbes, for the Bureau of Mines, were advocates.

Jan 1, 1952

By T. A. Rickard

The lodes of Cripple Creek, Colo., partake of the composition of the geological formation which they traverse. The prevailing rocks are andesitic breccia, lying upon granite, and also bodies of phonolite, trachytic phonolite, nepheline-basalt, etc., penetrating both the granite and the breccia. At Kalgoorlie, in West Australia, the prevailing rock is schistose, and has not been certainly identified, though microscopic sections indicate the probability that it was originally an acid eruptive. The lodes are essentially bands, more highly schistose than the encasing rock, and impregnated to a notable degree with disseminated pyrites and secondary calcite. During 1899 Cripple Creek produced 425,590 tons of ore, having a gross value of $15,658,254; during the same period the output of Kalgoorlie was 467,048 tons, valued at $17,724,587. In chemical composition, the ores at Cripple Creek and Kalgoorlie, respectively, present differences equally interesting to the petrographer and the metallurgist. In both cases we have to deal with altered eruptives as the matrix of the ore; but the much older rock of Kalgoorlie has undergone more decompo-

Jan 1, 1901

By Hobart M. Kraner

THE mineralogy of blast furnace sinter is of interest because its mineral content is one of the important factors contributing to its character. There are so many other factors affecting the properties of the sinter, however, that it is well to mention them here. The proportion and character of the raw materials, that is, raw ores, concentrates, returns, and fuel, as well as the mixing and the water content, all have a marked effect on the physical properties of the product and the degree to which sintering action can be carried on. The process of sintering is a relatively fast operation. In as much as appreciable time is required to carry on processes of fusion in such masses of low thermal conductivity, large lumps of hematite ore frequently remain unfused and partly unchanged in state of oxidation in the sintering process. The kind, the grain size, and the amount of fuel used affect both the completeness of the fluxing reaction and the prevailing atmosphere. The rate of reduction in laboratory tests is not only dependent upon the state of oxidation of the sinter but also upon the sizing and porosity.

Jan 11, 1953

By R. V. Whetsel, V. R. Garfias

Petroleum production in the Mexican fields during 1932, estimated at 32,400,000 bbl., was only 564,000 bbl., or about 2 per cent less than the 1931 total. Production in the northern fields declined approximately 1,100,000 bbl., the Tehuantepec output showed a drop of 340,000 bbl. and the South fields gained 865,000 barrels. Wildcatting continued at a reduced rate, the only successful completion being Presa No. 2 well which at a depth of 1535 ft. produced about 7,000,000 cu. ft. of gas. This well is an offset to Alberca No. 1 completed during 1931. General conditions in the petroleum industry coupled with the additional burden of the 21c per bbl. duty on oil imported into the United States further discouraged development activity in Mexico during 1932. Production of the Mexican fields in 1932 was distributed as follows: Production (U. S. Barrels) 1931 1932 _______________________________________________1________________________ Northern fields.................................... 14,092,000 13,000,000 South fields....................................... 10,535,000 11,400,000 Tehuantepec fields............................... .. 8,000,000 32,964,000 32,400,000 Since their discovery to the end of 1932, the fields have produced as follows: (U. S. Barrels) Northern fields..................................... 681,300,000 South fields........................................ 967,200,000 Tehuantepec fields.................................. 40,540,000 1,689,040,000 The tremendous productivity of the Mexican wells and the very small number actually drilled in the proven areas is shown in the following table:

Jan 1, 1933

By H. M. Howe, E. C. Groesbeck

Fig. 1 shows a volute aging break which developed spontaneously in a hardened and tempered steel helmet between 19 and 38 days after it had been tested ballistically. A similar break, shown in Fig. 2, developed spontaneously in a similar helmet about 40 days after the ballistic testing. In this case the rupture occurred abruptly and with a loud report. The path of rupture in this second case, though much the less regular, is the more interesting of the two, in that it is an approximation to two parallel volutes centered at the point of impact of the projectile, just below D. Several weeks later, after the photograph for Fig. 1 was taken, a similar doubling of the volute crack occurred in this helmet, starting from the end of the eyelash crack near A and spreading thence to the left contra-clockwise for about 1/2 in. The negatives from which these pictures are made have not been touched up in any way, save writing the letters on them. In both cases the trajectory of the bullet was normal to the initial surface at the point of impact, and in both the helmet passed the ballistic test without detectable cracking, under a velocity of impact not far below that which usually causes perforation. The initial surface itself was very nearly spherical throughout the region covered by the break.

Jan 1, 1920

The Mining Journal Annual Review. The Mining Journal, London. $1.00, 200 pp., 1952.-Contains 70 specially contributed articles reporting on events in the metalliferous mining industry throughout the world during 1951. The articles are written from the standpoints of: Economics, world mining fields, progress reports on Empire mining companies, and British mining taxation. The review has appeared for a period of 20 years. Technical developments in mining, ore treatment, refining, and metallurgy are covered. Dun & Bradstreet Reference Book. Dun & Bradstreet Inc. 4000 pp., 1952. -Changes, brought about by the expanding economy, have been made for the three million listings for the United States and Canada. Planning for the changes started more than 10 years ago. New listings have been included for the metals and mining industries on all levels. The rapid development and specialization of industry have made the old symbols used in previous editions outmoded and a new system is substituted. Atlas of World Mineral Resources, . Edited by William Van Royen and Dr. Oliver Bowles. Prentice-Hall Inc. $10.75, 180 pp., 1952.-Scheduled for publication this fall, the book contains information that has never been published in map form before, as well as much that has not been presented in map form for many years. Facts on 29 minerals most important in world trade are dealt with, along with interpretation of all data available on each mineral, discussion of the world's mineral economy from viewpoint of specific minerals related to mineral exploration, geographical distribution of world's consumption, and appraisal of the adequacy of world's mineral resources.

Jan 1, 1952

By Beverley S. Randolph

The coal-measures of George's Creek coal-region, in Maryland, lie in a comparatively flat synclinal basin, about 4 miles wide. The dip of the measures is, in places near the edge of the basin, as much as 20 feet in 100. The Pittsburgh seam, known locally as the " Big Vein," is the only seam worked at the present time. Ocean No. 3, one of the large mines of the Consolidation Coal Company, has its opening on the outcrop of the Pittsburgh seam, in a ravine which cuts into this seam to such an extent as to bring this opening to within a mile of the axis of the basin. After working all the coal to the rise of this point, the mine was further developed by extending a slope down the dip of the seam, making such an angle with the line of greatest dip as to give a grade varying from 1 to 10 per cent., down which the empty cars carry a rope from a single-drum winding-engine. The coal was worked from each side of this slope in successive Iifts during its progress. From the top of the slope, for a distance of 4000 feet to the fourth lift, the " make " of water is drained by gravity through a heading into the adjoining mine. Below this point the water was pumped into this same heading, at the fourth lift, from which point, as before mentioned, it flowed by gravity.

Jan 1, 1895

By Milton E. Wadsworth, W. Martin Fassell, William H. Dresher

A study of the rate of dissolution of molybdenite (MoS2) in alkaline solution was carried out under carefully controlled conditions. Effects of temperature, oxygen over-pressure, and KOH concentration were evaluated. Studies were made in the temperature range 100°C to 175°C and in the pressure range 0 to 700 psia of oxygen. Under these conditions molybdenite was found to leach according to a linear mechanism. Both oxygen over-pressure and KOH concentration were found to control the rate of leaching. The mechanism has been explained in terms of adsorption of oxygen at the molybdenite surface followed by configurational rearrangement of the adsorbed molecules. The hydroxyl ion dependency is believed to be diffusion-controlled. Laboratory batch studies have shown that molybdenite can be readily dissolved in alkaline solutions under moderate conditions of temperature and pressure. Commercial application of this process to the production of ferro-molybdenum and molybdenum chemicals is promising in view of the ease of dissolution of molybdenite and the relatively noncorrosive conditions involved in the process.

Jul 1, 1956

By G. K. N. S. Subasinghe

An attempt has been made to explain the behavior of a pinched sluice in terms of the established theories of fluid mechanics and mineral processing. A method has been developed to calculate the underflow discharge by assuming a logarithmic velocity distribution and free gravity fall through the discharge slot. The concentration profile of solids over the depth of flow has been shown to comply with Bagnold's theory of dispersive shear, rather than turbulent sediment transfer. Even although the results can be explained qualitatively by the Bagnold theory, their complete quantitative analysis will not be possible until more work is done. Consequently, an empirical equation has been developed to predict underflow pulp densities. It has been shown that the process of the segregation of the heavier mineral beneath the lighter can be described by a first order law. From the results obtained, a computer model of the pinched sluice has been developed. This predicts the underflow grade, pulp density and flow rate in terms of the feed and operating conditions. The model can also be used to determine the effect of a change in operating conditions, and for the optimization of rougher, cleaner, and scavenger circuits.

Jan 1, 1984

By Alan D. Randolph

INTRODUCTION The production of fines is an unwanted side-effect in most crystallization processes. The definition of “fines" is relative to the size of the desired product and varies from <30 mesh for coarse KC1 fertilizers to subsieve organic material produced by salting-out pro- cesses. Sometimes a well-developed fines distribution is necessary in the production of large crystals, e.g. the fines removal stream from a potash crystallizer. The production of fines is usually not desired in a crystallization separation step. However, product purity can either improve or degenerate with a decrease in crystal size depending on the relative importance of product washing vs mother liquor occlusions in determining over-all purity. Typically, both washing efficiency and mother liquor occlusions decrease with decreasing particle size. Fine crystal distributions have historically been difficult to measure and categorize; however this situation is changing rapidly with the use of electronic particle counters of the electrical zone- sensing or light scattering type. In fact, fine-crystal measurement is perhaps the key to better understanding and control of coarse- crystal crystallization processes. The fine-crystal distribution carries much useful information from which nucleation and growth rates can be inferred. The purpose of this paper is to briefly discuss a few crystallization processes in which production and/or measurement of fines is important and to categorize the process conditions which yield a fine- crystal product.

Jan 1, 1980

By Harry Seltz

INTERMETALLIC compounds are formed in many binary metal systems. Some compounds are stable to their melting points, and others decompose at lower transition temperatures. Even those of the first class are dis-sociated in the liquid state, as indicated by the continuous for in of their solubility curves at their melting points1. While the lattice structures of some of these compounds have been determined, their thermodynamic properties have not been investigated. In this paper is described the determination of the free energy and heat of formation of the compound CdSb, which is of the first class mentioned above, melting congruently at 455° C. This compound shows a rhombic structure, and the lengths of the edges of the elementary cell containing four molecules are: a =6.52, b = 8.60, c = 4.16 A.2 There are three possible methods of determining the free energy of formation of a compound of this type. The first method, applying the third law of thermodynamics, requires the measurement of its heat capacity preferably to liquid hydrogen temperatures, and a calorimetric determination of its heat of formation. The second method involves the study of the equilibrium of the compound in some gas reaction, such as: CdSb + CO2 = CdO + CO + Sb From the known free energies of formation of CdO, CO2 and CO the free energy of formation of CdSb could be calculated. The third method measures the electromotive force of a galvanic cell in which the cell

Jan 1, 1935

By George Laird

IF IT IS true that Sir Walter Raleigh lost his head for his failure to find gold in the Guianas, the trumped up charge of "treason" might better have been "con-tributory negligence." That systematic investigation and development of the gold-bearing areas of both Dutch and French Guiana have not been accomplished is not due so much to the lack of gold as to the geo-graphical, physical and climatic conditions of the two colonies. The Dutch, as a people, are not prospectors. The French look upon "Cayenne," or French Guiana, as DJOEKA BOATS USED IN RIVER TRANSPORTATION. just what it is: a penal colony, which produces a certain amount of balata, gold and essential oils, all of which can be purchased from the natives with far less physical exertion than they can be secured from the "bush" or jungle. The colonies have had their gold "booms," and dur-ing these periods the production has increased to a considerable amount, but the hardships to be endured in reaching the fields, the cost of transporting tools and supplies, the ever-present fevers, the bite of the "57 varieties" of insects and, lastly but not leastly, the abundance of rum in the seaport towns, dampen the ardor of even the strongest; the production of gold is left to the "pork knocker" or illegal gold digger and to the comparatively few producing "mines."

Jan 10, 1922

The Library of the above-named Societies is open from 9 A.M. to 10 P.M. on all week-days, except holidays, from September 1 to June 30, and from 9 A.M. to 6 P.M. during July and August. The Library contains about 55,000 volumes, including sets of technical periodicals and the publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library can render valuable service through correspondence; letters requesting information will receive special attention. The Library is prepared to furnish references and copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish general information as to the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape. The members of the Institute can be of service to the Library by forwarding copies of mining reports, maps privately issued, and similar material, which will be classified, indexed, and made available to other members. Suggestions for additions to the Library, either by purchase or personal solicitation as gifts, will be welcomed. It is hoped that members while in the city will use the Library freely, and assurance is given that most careful service will be rendered to them.

Jan 2, 1915

THE Institute assembled in Packer Hall of the Lehigh University, the President, Mr. David Thomas, of Catasauqua in the chair. Professor Henry Coppée, President of the Lehigh University, made an address of welcome to the Institute, and placed at its disposal a convenient hall for purposes of meeting. Mr. Thomas tendered his resignation as President of the Institute, as advancing years prevented him from actively participating in its meetings. The Institute declined to accept the resignation, and, on the assurance that active duties would not be expected of him, Mr. Thomas was induced to withdraw it. Invitations were received from Mr. B. C. Webster, President of the Lehigh Zinc Company, to visit the mines and works of the company; from Mr. Charles Brodhead, to visit the Chapman Slate Quarries; and from the Lehigh Coal and Navigation Company, to visit their works at Summit Hill and Mauch Chunk and the Nesquehoning Tunnel. The Council reported the names of persons already elected in the two classes of members and associates. The following resolutions were passed : Resolved, That a committee of three be appointed, who shall take into consideration the printing and publishing of papers originating with the Institute, and that a uniform system as regards size and execution be adopted. The committee appointed consisted of Messrs. R. W. Raymond, E. B. Coxe, and the Secretary. Resolved, That the Council design and prepare a seal for the Institute at the earliest practicable time. Resolved, That a committee of six, with power to add to its numbers, be appointed to examine into the question of the more economical production of iron in this country. The committee appointed consisted of Messrs. G. W. Maynard,

By Robert G. Van Nostrand, John H. Henkel

TRANSIENT potentials obtained in resistivity prospecting can be separated into two classes. The first is electromagnetic, has a comparatively short time constant, and increases in relative amplitude as the electrode separation is increased. These electromagnetic transient potentials, of which an excellent theoretical treatment is given by Yost,1 are the result of changes in the current and can be classed as differentiated signals. The second class is electrochemical, has a comparatively long time constant, and decreases in relative amplitude as the electrode separation is increased. The electrochemical signals are generated by the current flow itself and can be classed as integrated signals. The transient potentials due to electrochemical factors are the subject of this article. The phenomenon is referred to as induced polarization. Schlumberger2 was the first worker to observe induced polarization, but he was unsuccessful in attempts to apply the principles of induced polarization in electrochemical prospecting. Other workers, notably Bleil3 have studied polarization and in some cases pointed out its possibilities, but no theory has been presented that describes polarization and its time dependence adequately. It is the purpose of this discussion to present the essence of a theory to geo- physicists and to show that it leads to results consistent with experimental evidence. The theory on which this analysis is based has existed in electro- chemical circles since 1910.4

Jan 3, 1957

By Peter Hood

Data on worldwide geophysical activity in mining exploration programs is collected annually by the Geophysical Activity Committee of the Society of Exploration Geophysicists as part of a continuing service to the industry. The data is obtained by sending out questionnaires to all organizations (which are) known to be carrying out mining geophysical work; the organizations canvassed include mining companies, contractors, government departments and universities. The questionnaire is divided into three sections, namely ground methods, airborne methods and research. In 1968, 515 questionnaires were circulated throughout the non-Communist world and 283 replies were received which is a 55% return. A 67% return was received from the U. S. organizations surveyed so the statistics quoted in this report for the United States are reasonably reliable. This report is published in condensed form, but with emphasis on the United States statistics, with the permission of the Society of Exploration Geophysicists. It was presented at the 39th Annual International Meeting of the SEG in Calgary, Alberta, on September 15, 1969. Worldwide utilization of mining geophysical methods reached a new high in 1968 with total expenditures of United States $41.4 million, compared lo $32.3 million in 1967, representing a 28%, increase. The expenditure distribution by area and type of activity is shown in the graph on page 64. In terms of money spent, ground geophysical surveys accounted for 49% of the total, airborne survey&apos;s 36% and research 15%. The percentage of the money spent on ground geophysical surveys fell by approximately 7% from 1967, that for airborne surveys, increased by 5%, and for research the amount increased by 2%. Industry accounted for 79°1% of the total monies spent on mining geophysical activity in the world in 1968 and governments and universities 21 o%.

Jan 1, 1970