Search Documents

By George J. Young

DR . JOHN A . CHURCH, in his treatise on the Comstock Locle 1 gave a full and clear account of the conditions of the mine during the period of greatest activity. The difficulties in the way of deep mining at that time were excessive water and high temperature. The drainage of the mines taxed the financial resources of the mining companies, and the high temperatures restricted the capacity of the miners for underground labor. In spite of these difficulties exploratory work was continued until the financial burden of removing the water became too great. The companies then restricted the work to the upper levels. The years 1883 to 1886 marked the period of cessation of deep mining. For 12 years thereafter mining was confined to the levels above the Sutro tunnel; and, while the question of drainage was more or less agitated, nothing of importance was done until the formation of the Comstock Pumping Association in 1898. Since that time successive levels have been drained until, at present, on the north-end mines, a depth of 700 ft. below the Sutro-tunnel level has been reached. Mining is now carried on in the Ophir mine from the 1,700- to the 2,200-ft. levels, and a winze is being sunk to make connection with the 2,300-ft. level (the 2,450 ft. of the C. & C. shaft). In 1903-the Ward Shaft Association was formed to undertake the draining of the Central and Gold Hill group of mines, and at the present time a depth of 2,500 ft. has been reached in the Ward shaft. The situation at the Ward looks promis¬ing, and the 3,000-ft. level may be reached in the near future. It is proposed to establish a large pumping-station on this level, and then begin the opening of known ore-bodies and the prospecting for new ones. The main factors which have contributed to the successful solution of the drainage problem are the Sutro tunnel, the use of the hydraulic elevator as a sinking-pump, the concentration of pumping-units, and cheap electrical power. The question of high temperature and its control still remains as a minor but important problem. The temperatures encountered in the new workings are as great as those in the earlier periods. The Comstock was considered the hottest group of mines in the world, and I am not aware of similar conditions in any other mining-district. A water-temperature as high as 160° F. has been reported from the Ward shaft, and temperatures below the Sutro tunnel are very high in many instances.

Nov 1, 1909

Extremes in temperature and weather, along with the highly corrosive nature of acid leach solutions used at open-pit copper mines, necessitates the use of pipeline systems that are both corrosion resistant and impervious to the environment.

Jan 6, 1976

Large equipment for quarrying and for the various stages of crushing and grinding are the trend for new and existing operations. Included are large size haulage units, fast drilling equipment, impact crushers and large mills capable of high tonnage rates for metallic and nonmetallic minerals. In grinding, large-size mills continue as the choice in industries where grinding constitutes a major portion of the processing. Typical is a 10 x 34 ft two-compartment mill in closed circuit with an 18-ft diam air separator for cement. Other cement mill sizes are in the order of 12 x 36 ft, 2500 hp; 10 x 37 ft ball and rod (wet), 1400 hp; 13 x 36 ft, 3000 hp; 13 x 40 ft (wet), 3000 hp. Several installations of combination ball and rod mills have been made, and one of the largest is 12 x 45 ft. In connection with the wet grinding of raw materials, the DSM 270-degree screen has been installed in several cement plants with the intention of producing a material finer than 50 mesh. In ore processing, large autogenous mills (121/2 x 20 ft) are being installed.

Jan 2, 1964

By O. C. Wheeler

There was a marked increase in the investigation of undeveloped areas in Colombia during 1936. The Shell company commenced geological and geophysical investigations on an intensive scale in the Upper Magdalena Valley and at the end of the year had several geological and geophysical parties working in that area. These investigations were supplemented by aerial photography and it is understood that negotiations are under way for having this work continued. The Shell is reported to have acquired some options and leases on private properties in the Upper Valley region and in the western part of Cundinamarca. The Socony Vacuum was making preparations to begin seismograph work on its property north of the Sogamoso River, acquired in 1934 from Sefior Luciano Restrepo. This company will probably start drilling on the property during 1937. The Richmond Petroleum Co. (Standard of California) is said to have renewed geological investigations in the Upper Magdalena Valley above Honda. Local Colombian interests took an active part in applying for concessions on nationally owned lands in the area between the Carare and Magdalena Rivers. The application of the Sociedad National del Carare for a concession in this area was granted during the year. Subsequently an agreement was reached between this

Jan 1, 1937

By C. Dinis da Gama

Because of the growing importance of back analysis for the interpretation of rock slope failures, particularly in open pit mines, it is suggested a methodologic sequence of activities for dealing with those problems. The principal mathematical tools for the interpretation of the most common mechanisms of slope failures are reviewed, including methods of stress and strain analysis, which seem to be more powerful for parametrization studies, and for developing more realistic explanations of slope behaviour, such as the measurement of displacements. An application of those methods is described, using slope failures detected in a Brazilian uranium mine (Cercado), thus providing reliable shearing strength parameters for the rock mass discontinuites, which were used in the final pit design. The concept of using backanalysis results to supply input data for pit design was implemented by means of the excavation of an experimental trench within mine limits, where specific instruments were installed, and several slope failures were monitored and backanalysed, in order to yield information about sliding mechanisms in the future open pit.

Jan 1, 1983

By Oliver B. Hopkins

During the year 1936, a new high record was established for Peruvian production, the total amounting to 17,594,689 bbl., which brought the cumulative production of the country up to 205 million barrels. The 1936 figure represents an increase of 530,288 bbl. over that of 1935. The property of the International Petroleum Co. contributed 369,577 bbl. of this increase and the Lobitos property 158,233. Exploration work in the country was continued. The Selden Breck Co. examined a strip of the National Reserve in eastern Peru from Tambo del Sur to the Rio Pachitea. This company was granted a concession for a term of four years embracing approximately 50,000 acres near the confluence of the Rio Pachitea and the Rio Ucayali. During the year, the Peruvian Government commenced drilling a well on one of the reserved zones at Zorritos. At the end of the year, this well had reached a depth of 1300 feet. La Rrea-Parinas Estate.—Production on the La Brea-Parinas Estate of the International Petroleum Company, Ltd., reached an all-time high in 1936 of 15,126,491 bbl., an increase of 369,577 bbl. over the 1935 record. The total production from 1890 to 1936 was 163,668,014 barrels.

Jan 1, 1937

By W. F., Dietrich

THIS paper deals with the- methods of mining the high-grade clays of California. Although the majority of the clay pits in the state are operated on a scale that is small by comparison with most metal mines, this very fact results in a diversity of methods and gives rise to problems of selection of the method best suited to given conditions. Two or three operators in California produce approximately 500 tons per day of a single kind of clay from a single pit. About five varieties of clay are mined on a scale of 200 to 400 tons per day; not over fifteen varieties are mined on a? scale of 50 to 200 tons per day; and more than 50 varieties are mined at a rate of less than 50 tons per day. It is the aim of this paper to delimit, insofar as the data at hand permit, the conditions and scale of operations that favor the selection of each dominant method of mining that is actually being applied at California properties. Details of the occurrence and utilization of the clays of California have been given in a recent bulletin and are not considered here.

Sep 1, 1928

By Fleming, R. C.

ONE OF THE NEWEST developments of industry rising from the commercial application of scientific knowledge is in the making of solid carbon dioxide from the gas about 1925 the first efforts were made to manufacture "dry ice" on a large scale and at a price to permit widespread use. From that beginning the industry has grown to a consumption of 40,000 tons in 1930. Carbon-dioxide ice, as the name implies, is merely the gas compressed and cooled to a solid. The ice has a temperature of 109° F. below zero and is in many ways superior to water ice. It evaporates to a gaseous form so it is not wet and leaves no trace; in fact, one suggested minor use is as coasters under water glasses on the dining table. The gas is harmless except in large concentrations and. when the ice is used as a refrigerant, the resulting gas actually becomes a preservative, keeping oxygen away from perishable products. Not only does the ice have a greater amount of cold in a small volume than water ice but cooling is effected by direct contact of the resulting gas with the materials to be refrigerated rather than by convection air currents.

Jan 1, 1932

By Daniel T. Brian, O&apos

Exploration targets and results in the mining industry are commonly summarized in terms of tonnage and grade. Business appraisals require, as additional information, the expected profit or loss implied by the physical summay. The early incorporation of knowledge gained through financial analysis computations can provide a means for economically resolving many common exploration and development problems. Examples of such applications from the activities of exploration planning, reconnaissance, land acquisition, and development planning are presented. While prospecting for mineral deposits, geologists are frequently asked what they hope to find or have found. The response is usually descriptive, such as "50 million tons of 1% copper," and the economic implications are deferred until a capital investment decision is required. At that time, a financial analysis integrating the four analysis components is completed. These components are: 1) Tonnage and Average grade above cutoff grade 2) Capital and operating costs 3) Product value 4) Appropriate profit or loss accounting Close examination of these components reveals that there is no intrinsic reason for avoiding financial analyses at earlier stages in exploration, as long as the uncertainty of the estimate is realized. Tonnage and average grades are commonly estimated at early stages in exploration. For this component, the appropriate cutoff is the major uncertainty. Capital and operating costs are difficult to estimate before detailed quantitative information is available, but estimates useful for the types of applications pertinent to earlier exploration stages are possible. Product value estimates may or may not be difficult, depending on the pricing structure of the particular commodity. A simplified accounting procedure usually may be adopted without introducing any significant loss of validity. This paper describe some of the financial analysis applications which are pertinent during mineral exploration and deposit development. These applications lend additional insight during exploration planning, land acquisition, physical exploration, and development. The examples are oriented toward a hypothetical management investment policy which is based on a single criterion, a minimum 15% discounted cash flow rate of return. In reality, managements use multiple criteria. This simplification is convenient for purposes of presentation and does not invalidate the examples. Computers are useful, but not a requirement, for the applications described. The use of computers provides the results on a more timely basis at costs lower than equivalent manual computations. UNDERLYING PRINCIPLES AND ANALYSIS METHODS Data estimates are subject to uncertainty. The analyst may choose to assess this uncertainty by using one of two principles. Each principle has some advantages. The principle most commonly employed is "assumed certainty." Each financial analysis is based on one set of selected data, which may represent the average estimates, minimum expected conditions, etc. The critical data is identified by making successive calculations, varying the values used. Such studies, called sensitivity analyses, isolate the economic effect of various uncertainties, and guide the allocation of future efforts toward improving the overall accuracy of the analysis. A second principle, "assumed risk," examines the interactive effect of the current uncertainties by qualitatively assigning probability distributions to each data element. These probability distributions indicate the currently appraised chance that a given numerical value will prove to be true. The corresponding procedure, risk analysis, consists of processing many individual financial analyses, each analysis being based on randomly selected numerical values from the probabilistic distributions. The result is a numerical presentation of the uncertainty, but care must be exercised in the interpretation of results. The advantage of this procedure is the direct measurement of economic uncertainty caused by the interaction of uncertain estimates. Kennecott Copper Corp. has developed computer systems for accomplishing sensitivity and risk analyses.

Jan 1, 1970

By AIME AIME

THE following brief description of the main features of the, engineering work was prepared for the use of members of the American Society of Civil Engineers and members of the American Institute of Mining Engineers on the occasion of their visits to the tunnels at the time-of their respective. annual meetings in New York, January and February, 1905. DESCRIPTION. Those portions. of the Pennsylvania Extension into Manhattan and Long Island, lying east of the Terminal Station and west of the East River, have been designated as the " Manhattan ?Cross-town:. Tunnels." They traverse a section of the city second in importance only to the financial district, and one that includes the larger hotels, retail shops and theaters and the residences of many of the best known citizens. Section "D," consisting of twin tunnels for west-bound express and local passenger traffic, lies under Thirty-third Street from a point 400 ft. west of the west line of Sixth Avenue, eastward to the river shaft, situated in the block between Thirty-third and Thirty-fourth Streets east of First Avenue. Beginning at the east end, the tunnels are in separate excavations, leading westward from the subaqueous tubes, on a curve of large radius, gradually closing together until it is found more appropriate to drive them in a single excavation. At a point just west of Second Avenue they reach the tangent, aid from there westward lie directly under Thirty-third Street. At a point about 180 ft. west of the west line of Sixth Avenue, the center concrete-wall between the twin tunnels is omitted, and the excavation somewhat widened to make room for a third storage-track, and the tunnel continues to tile station portal in three-track section. Here reprinted through the courtesy of The United Engineering and Contracting Co. The half-tone blocks used for the illustration of this paper have been kindly supplied by the Chasmer-Winchell Press of New York, Pittsburgh and Cleveland.

Mar 1, 1908

By Sinha D. K.

As the main source of indigineous energy, coal has a big role to play in the development of national economy of India. Nationalization of the coal mining has brought the entire industry under the unit control of the Central Government following which an ambitious plan for increasing the coal production in the next few five year plans has been undertaken. In order to achieve best all round results, economy-mathematical models of Planning the total system, right from the highest to lowest hierarchial levels of decision making, have been proposed through a Global Model which is detailed in Local Models in stages right up to a mine. Optimum obtained by computer solution of the models would provide basis for objective decision making in the fields of selection of optimum plan for developing the industry, the coal fields and the mines with construction and/or reconstruction of mines, capacity optimization of enterprises and mines therein. Different types of Models and the optimization processes are presented.

Jan 1, 1977

By Joseph D. Weeks

Manganese has, until recently, been most highly esteemed as a good thing to keep out of steel. Its value in the process of mannfacture has been fully recognized, but after it has played its part in the crucible or the converter, then the less of it the better. It is true that the mission of this metal and its influence upon the character of steel has been a source of much controversy. Our own Holley, in one of his special reports on ferromanganese: I, states that ''it has been suspected by some, and believed by a few, while it is still denied by many, that manganese as an ingredient in steel has not only a body-giving and toughening influence, but a positive neutralizing influence upon any excess of hardening or cold-shortening substances, as phosphorus." In another paper on the same subject he states that " it should appear from such facts as we have that manganese toughens" the structural steels, "increases their soundness and prevents red-shortness." Notwithstanding these rather guarded assertions as to its value, the general belief, it will be found, is with Dr. Siemens, that manganese is " merely a cloak to hide impurities," and its presence in steel has been endured, not welcomed. But whatever may have been the difference in opinion as to the

Jan 1, 1885

By Robert S. Dewey

AS a result of drilling operations during 1943, West Texas again added sufficient new oil reserves to replace the oil produced during the year, but failed to maintain its position in currently available reserves because the deeper discoveries will require years for development. Drilling failed to provide the additional oil necessary to meet the increase in current and anticipated market demand. Although 13.3 per cent of the total footage drilled was in wildcat exploration, the ratio of oil discoveries to total wildcats was less in 1943 than in 1942, but comparable to that in 1941. Of the 732 field wells completed, 270 were at Slaughter, 55 at Wasson, 45 at Mascho and 31 at North Cowden. As of Dec. 31, 1943, there were 361 drilling wells including 71 wildcat and 290 field wells; 19.7 per cent were wildcats. It is anticipated that the percentage of wildcats of the total wells will be higher during 1944 than in either 1942 or 1943. Tables 3 and 4 present a three-year comparison of drilling activity and illustrate the downward trend of development that has been in effect during that time. Because of development lag in the deeper Ordovician fields, several years elapse before 2 sufficient number of wells is completed to give a substantial producing rate. As these new oil reserves cost more to find, and will cost more to produce on a barrel basis than the oil marketed during the year, their reserve replacement value to the industry is less in money. Costs While complete costs for deeper drilling are not yet available for analysis, it is evi- dent from the data on drilling rates to comparable depths, contract prices, and general increases in costs, that the cost of drilling has risen approximately 20 per cent during the year. One representative drilling contractor estimates that the average drilling time on a 5000-ft. field well has increased nearly one third and that out-of-pocket costs have increased a dollar per foot. Three major factors contribute to this increased cost: (I) less experienced labor, (2) deterioration in mechanical equipment and expendable material, and (3) increased contract prices. In the past, when there were more drilling rigs than wells to be drilled, some contractors would cut their drilling profit to keep their personnel and rigs working. As this practice is no longer necessary, the contract prices are adjusted upward to assure a profit. On deep and difficult drilling, contracts are let on a cost plus basis. A number of mechanical difficulties have become evident. Inferior quality of steel used in drill pipe and rock bits has added appreciably to drilling time and cost. Contractors are experiencing delay in obtaining repair work and repair parts for prime movers. As the length of drilling time required an shallow-field wells has not increased in proportion to that on deeper wells, it seems that the medium-sized drilling rig is better adapted mechanically than the heavy one to the work imposed. One of the main deficiencies in the heavy rig equipment is inadequate pump capacity. Drilling Mud The increasing amount of deep drilling has emphasized the importance and relationship of good mud to efficient and suc-

Jan 1, 1944

By Robert S. Dewey

AS a result of drilling operations during 1943, West Texas again added sufficient new oil reserves to replace the oil produced during the year, but failed to maintain its position in currently available reserves because the deeper discoveries will require years for development. Drilling failed to provide the additional oil necessary to meet the increase in current and anticipated market demand. Although 13.3 per cent of the total footage drilled was in wildcat exploration, the ratio of oil discoveries to total wildcats was less in 1943 than in 1942, but comparable to that in 1941. Of the 732 field wells completed, 270 were at Slaughter, 55 at Wasson, 45 at Mascho and 31 at North Cowden. As of Dec. 31, 1943, there were 361 drilling wells including 71 wildcat and 290 field wells; 19.7 per cent were wildcats. It is anticipated that the percentage of wildcats of the total wells will be higher during 1944 than in either 1942 or 1943. Tables 3 and 4 present a three-year comparison of drilling activity and illustrate the downward trend of development that has been in effect during that time. Because of development lag in the deeper Ordovician fields, several years elapse before 2 sufficient number of wells is completed to give a substantial producing rate. As these new oil reserves cost more to find, and will cost more to produce on a barrel basis than the oil marketed during the year, their reserve replacement value to the industry is less in money. Costs While complete costs for deeper drilling are not yet available for analysis, it is evi- dent from the data on drilling rates to comparable depths, contract prices, and general increases in costs, that the cost of drilling has risen approximately 20 per cent during the year. One representative drilling contractor estimates that the average drilling time on a 5000-ft. field well has increased nearly one third and that out-of-pocket costs have increased a dollar per foot. Three major factors contribute to this increased cost: (I) less experienced labor, (2) deterioration in mechanical equipment and expendable material, and (3) increased contract prices. In the past, when there were more drilling rigs than wells to be drilled, some contractors would cut their drilling profit to keep their personnel and rigs working. As this practice is no longer necessary, the contract prices are adjusted upward to assure a profit. On deep and difficult drilling, contracts are let on a cost plus basis. A number of mechanical difficulties have become evident. Inferior quality of steel used in drill pipe and rock bits has added appreciably to drilling time and cost. Contractors are experiencing delay in obtaining repair work and repair parts for prime movers. As the length of drilling time required an shallow-field wells has not increased in proportion to that on deeper wells, it seems that the medium-sized drilling rig is better adapted mechanically than the heavy one to the work imposed. One of the main deficiencies in the heavy rig equipment is inadequate pump capacity. Drilling Mud The increasing amount of deep drilling has emphasized the importance and relationship of good mud to efficient and suc-

Jan 1, 1944

By Zay Jeffries

OF the new production of non-ferrous metals in 1930 gold will rank first in value. We usually think of copper as the most important non-ferrous metal. The copper industry as a whole, that is, adding copper production to copper fabrication, is the largest non-ferrous metal industry. Prior to the world war; however, gold led in value of new metal produced. During the war copper passed gold in value, but gold regained its position during the 1921 depression. For the past several years copper has again passed gold, but in 1930 gold promises again to regain the lead. The gold producer has at times been called a social parasite, largely because we ' cannot eat or drink gold, or because we cannot use it for clothes or for the construction of buildings. Let us briefly examine this accusation.

Jan 1, 1930

By D. M. Wade, F. F. Redfield

PRODUCTION at Aguilar started in 1936 and by 1942 the mine had reached a peak of 25,000 tons a month. Present production is only about 60 per cent of this capacity because of difficulties in railroad transportation and the rationing of fuel oil brought about by the war. In the early years, cut-and-fill stopes were tried, but square sets were found to be the most practical method in the southern section of the mine, where blocky, treacherous ground and greater mining widths are prevalent. Square sets and opencut mining were the rule until 1942, when it became increasingly difficult to get mine timber. The ore beds in the northern section of the mine were found amenable to cut-and-fill stoping as the rock was firmer and the veins narrower. At present 69 per cent of the ore comes from cut-and-fill stopes, 27 per cent from opencut, and only 4 per cent from square-set stopes. Massive galena and sphalerite with comparatively little quartzitic gangue constitutes the higher-grade ore. The gangue minerals that can be detected by eye in low-grade ore are rhodonite, wollastonite, and pyrrhotite. Wall rocks range from shale to quartzite, with occasionally a little limestone.

Jan 1, 1947

By C. D. Broadbent

Open pit blasting can be a low cost routine or a high cost bottleneck depending on geology, environment and the operator's ability to master site conditions. Because blasting is a repetitive operation, there should be ample opportunity to optimize the process; but ordinarily this optimization is rarely achieved and then only if conditions remain consistent and predictable. Often, however, and particularly with porphyry coppers, hidden differences in rock characteristics nullify the operator's best efforts. At a porphyry copper deposit being mined by Kennecott Copper Corporation, all of the following rock types occur; oxidized and fresh porphyry, altered and silicified limestone, explosion breccia, rhyolite, sandstone, shale and several others. The units can cover large areas or be limited to a few tens of feet in maximum dimension. They are rarely visible on the bench surface and often do not show up in the bench slope. Even though the blastability of these rocks varies substantially, a generally-uniform blasting pattern was formerly used with disappointing results. Secondary blasting was often required and high bottoms occurred frequently, overblasting wasted drilling time, and explosives caused excessive throw.

Jan 4, 1974

By A. M. Radigan, W. G. Prast

Various industrial minerals that are traded internationally receive support from governments, enabling these materials to be more competitive. The role of government in encouraging nonmetallics exports ranges from the ownership of an integrated mining company to partial or selective government ownership, to the sponsorship of exporter organizations. In certain cases, regional governments have a direct stake in the industrial minerals industry. This paper assesses the commercial impact of these involvements.

Jan 1, 1984

By W. M. Weigel

LESS advances in the technology of non-metallic minerals than for several years past mark 1931, and the cause is easily found. The universal depression and decreased markets for non-metallic as well as other mineral commodities has forced the producers to cut out all unnecessary expense and reduce operating costs to a minimum in order to keep going, even on a reduced output, and to prevent insolvency. The result. has been that but 'little research has been carried on, and such as has been completed has in but few cases been put into commercial practice on account of the expense involved in new equipment and plant changes. The trend in the industry has been more economic than technologic, and the greatest effort put on market studies and sales attempts to expand markets and scrutiny of present operating 'practice leading to reduction of cost of production. This tendency has been increased by highly competitive conditions and the buyer's market which has prevailed and to the fact that price has been a greater factor than quality in placing orders. Only in cases where improvements in technology would immediately and effectively reduce costs or where in special cases there was but little competition with almost a monopoly control has actual technical development taken place.

Jan 1, 1932

By Edwin Hopkins

THE year 1923 started a few days after the Venezuelan Oil Concessions, Ltd., discovered a 140,000-bbl. well at. La Rosa and a well of between 2500 and 5000 bbl. at La Paz, on the opposite side of Lake Maracaibo. These nearly simultaneous events changed, overnight, the general aspect of oil affairs in Venezuela. Up to that time, big things had been expected by the companies then in the district, but many major companies had shown little interest in the country. Within a few weeks the Pure Oil. Co. and the Gulf Oil Corpn. entered the field and acquired large properties. The Texas Co. purchased several concessions and the Standard of California, Atlantic Refining Co., and Mexican Petroleum Co. established offices. Representatives of many other companies visited the district during the first few months of the year. The sudden influx of buyers naturally caused a great rise in prices and this, together with overproduction in the United States, doubtless caused the slowing up of concession transfers in the latter part of the year. The following property transfers occurred: (1) The Gulf Oil Corpn. contract with the Maracaibo Oil Exploration Corpn., whereby the Gulf acquired the right to select 100,000 acres from the Maracaibo's zones. (2) The Gulf Co. purchase of one-quarter interest in seven concessions of the New England Oil Corpn., Ltd. (3) The Gulf Oil Corpn. purchase of several concessions of Kunhardt and others in the Perija district. (4) The Gulf Oil Corpn. purchase of certain portions of the one-kilometer Lake zone that were not covered by parcels or Government reserves (namely the "sobrantes"). (5) Pure Oil Co. purchase of all Government reserves turned back by Maracaibo Oil Exploration Corpn. in the districts of Mara and Miranda. (6) Standard Oil Co.: of New Jersey deal with the British Controlled Oilfields, Ltd., for control of approxi-mately the eastern third of the .district of Buchivacoa, state of Falcon. (7) Royal Dutch deal with the British Controlled Oilfields, Ltd., for the control of the central third of the district of Buchivacoa, Falcon. (8) The Texas Co. purchase of several concessions in Perija and one west of Mene Grande on the east side of Lake Maracaibo. (9) Purchase by the British Equatorial Oil Co., Ltd., of Goverment reserves corresponding to certain Creole Syndicate parcels under the margin of Lake Maracaibo near La Paz. (10) The Lago Petroleum Co. acquired a concession on all of Lake Maracaibo except a 1-Km. strip along the shore.

Jan 3, 1924