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By K. R. Weller

The Ardlethan Tin Ltd. concentrator typically recovers 55% of the tin in a gravity concentrate at 51% grade from fresh ore assaying 0.5% Sn. Coarse gravity concentration is performed in a complex circuit involving Reichert cones, spirals, shaking tables and two regrind mills. The paper describes how flow and size-by-size sample data from a steady-state survey were used to construct a computer model of the plant involving 46 process streams. The data reduction involved a computer- aided mass balancing technique, recovery-size modelling of gravity concentrators and the use of a mineral dressing flowsheet simulator. The model was used to simulate possible rearrangements of the available equipment. Early simulations indicated that improved performance could be obtained by using spirals to-treat cone middlings or tailings rather than cone concentrates. A test spiral rig was used at Ardlethan to determine typical performances for all cone product streams and the results were incorporated in new simulations. A revised circuit was recommended and implemented by Ardlethan Tin as far as physical restraints within the plant would allow. Production figures show that a substantial increase in tin recovery and 10-15% increase in milling rate were achieved following the circuit changes, and these improvements were sustained over a six month period.

Jan 1, 1984

We, the undersigned, being all persons of full age and citizens of the United States and a majority residents of the State of New York, desiring to form a corporation pursuant to the provisions of the Membership Corporations Law for the purpose of incorporating, as provided in Section 5 of Article I of said law, the existing unincorporated association known , as American Institute of Mining and Metallurgical Engineers, Incorporated, do hereby make, acknowledge and file this Certificate for that purpose, and do certify as follows I That the American Institute of Mining Engineers is an unincorporated association organized and existing with the object of promoting the arts and sciences connected with the economic production of the useful minerals and metals and the welfare of those employed in these industries by means of meetings for social intercourse and the reading and discussion of professional papers, and to circulate by means of publications among its members and associates the information thus obtained II That the persons duly appointed or designated to manage the affairs of said association are designated by the rules thereof Members of its Council, that the undersigned are all members of said Council as the same was constituted on the 29th day of December, 1904

Jan 1, 1952

By M. G. Cheney

Careful estimates indicate that during 1942 new discoveries and extensions in West Central Texas added oil reserves slightly in excess of the eight million barrels produced. Drilling activity fell 40 per cent below 1941 and 82 per cent below the normal drilling activity of the late 1920's. Total production for the district continued its downward trend, now being less than % of the 42.7 million barrels peak in 1921. Rapid revival of activity is not probable under existing conditions, as costs of discovery, development and operations on the average probably now exceed current market price for the oil, the latter having remained constant since the spring of I941. Costs have advanced materially since the third quarter of 1941, when reports to the Tariff Commission indicated a margin of profit of 13.3 per barrel. Physical as well as economic conditions are holding back the amount of drilling in this district. The lenticular sands are not suited to 40-acre spacing regulations. There is no surplus of experienced oil-field labor. To reduce costs, much second-hand material is used for all except the deeper wells.. Price controls have retarded movement of used equipment by prescribing maximum prices that arc too low for the better grade materizl, thus making , owners reluctant to sell. On the other hand, buyers are unwilling to pay ceiling prices asked by sellers for poor material. Seventeen new oil fields and five new gas fields were found during 1942. Extensions and deeper 'drilling brought favorable results in eight older fields. The most significant new developments appear to have been in Coleman, Jones, Shackelford and Taylor Counties. A 5800-ft. completion in Wise County brought this county into the producing column for the first time. None of these new discoveries can he rated above one million barrel reserve on the basis of present development. Probably the most important development was discovery of a deeper pay (Gunsight lime) in the Wimberly field of Jones County, which shows promise of producing over an area of about 1000 acres. Jones and Shackelford Counties still lead the district in total annual production. Discovery of the Reddin pool, north central Taylor County, is credited to geochemical methods, making one success out of five or more wildcats based on such methods. Geophysical surveying increased decidedly during 1942 and returns from these studies are expected during coming years. Most of the wildcatting in the district is still based on surface and subsurface geological structural mapping, study of log data as to distribution of prospective producing reservoirs, and drilling in proximity to previous showings of oil and gas. Geological debate continues as to the proper correlation of the 100 to 300 ft. of gray lime that has produced more than 100 million barrels in the Parks, Brecken-ridge, Curry, Eliasville, Ibex, Pioneer and other important fields of this district. Fossils indicate that this limestone is younger than the Atoka beds of Oklahoma. On a structural basis most geologists include this formation with the Bend but a number of paleontologists believe it is more properly classified with the Strawn.

Jan 1, 1943

By M. G. Cheney

Careful estimates indicate that during 1942 new discoveries and extensions in West Central Texas added oil reserves slightly in excess of the eight million barrels produced. Drilling activity fell 40 per cent below 1941 and 82 per cent below the normal drilling activity of the late 1920's. Total production for the district continued its downward trend, now being less than % of the 42.7 million barrels peak in 1921. Rapid revival of activity is not probable under existing conditions, as costs of discovery, development and operations on the average probably now exceed current market price for the oil, the latter having remained constant since the spring of I941. Costs have advanced materially since the third quarter of 1941, when reports to the Tariff Commission indicated a margin of profit of 13.3 per barrel. Physical as well as economic conditions are holding back the amount of drilling in this district. The lenticular sands are not suited to 40-acre spacing regulations. There is no surplus of experienced oil-field labor. To reduce costs, much second-hand material is used for all except the deeper wells.. Price controls have retarded movement of used equipment by prescribing maximum prices that arc too low for the better grade materizl, thus making , owners reluctant to sell. On the other hand, buyers are unwilling to pay ceiling prices asked by sellers for poor material. Seventeen new oil fields and five new gas fields were found during 1942. Extensions and deeper 'drilling brought favorable results in eight older fields. The most significant new developments appear to have been in Coleman, Jones, Shackelford and Taylor Counties. A 5800-ft. completion in Wise County brought this county into the producing column for the first time. None of these new discoveries can he rated above one million barrel reserve on the basis of present development. Probably the most important development was discovery of a deeper pay (Gunsight lime) in the Wimberly field of Jones County, which shows promise of producing over an area of about 1000 acres. Jones and Shackelford Counties still lead the district in total annual production. Discovery of the Reddin pool, north central Taylor County, is credited to geochemical methods, making one success out of five or more wildcats based on such methods. Geophysical surveying increased decidedly during 1942 and returns from these studies are expected during coming years. Most of the wildcatting in the district is still based on surface and subsurface geological structural mapping, study of log data as to distribution of prospective producing reservoirs, and drilling in proximity to previous showings of oil and gas. Geological debate continues as to the proper correlation of the 100 to 300 ft. of gray lime that has produced more than 100 million barrels in the Parks, Brecken-ridge, Curry, Eliasville, Ibex, Pioneer and other important fields of this district. Fossils indicate that this limestone is younger than the Atoka beds of Oklahoma. On a structural basis most geologists include this formation with the Bend but a number of paleontologists believe it is more properly classified with the Strawn.

Jan 1, 1943

By T. W. Healy, P. Somasundaran, D. W. Fuerstenau

The flotation behavior of quartz in the presence of alkyl ammonium acetates as a function of alkyl chain length has been interpreted in terms of hemi-micelle formation at the solid-liquid interface. The van der Waals cohesive free energy that is responsible for hemi-micelle formation has been found from these results to be 1.0 kT per CH2 group. This is in excellent agreement with literature values obtained from research on the properties of micelles in bulk systems. Collectors of the type CH3(CH2)n-2CH2-P, where P is a polar group and n is the number of carbon atoms in the straight alkyl chain, will induce flotation of an appropriate mineral at lower concentrations as n increases. This reduction in collector concentration with increasing n has been reported for such systems as xanthates on sulfides1,2 and amines on quartz.' The effect of chain length of alkyl surfactants on such solution properties as conductivity,' surface tension,' and solubility6 and such interfacial properties of solids as contact angle7 and electrokinetic potential8 have received considerable attention, but only limited quantitative descriptions of the effects have been given. The electrokinetic studies of alkyl amine salts on quartz indicated that the solution concentration of collector at which the marked change in electrokinetic potential of quartz occurs decreases systematically as the length of the alkyl chain increases. The aim of the present work was to obtain a quantitative description in terms of current theories of flotation of the effect of the hydrocarbon chain of alkyl ammonium acetates on the flotation behavior of quartz. BASIC PRINCIPLES The marked changes in electrokinetic potentials of quartz in dodecylammonium acetate (DAA) solutions were postulated to result from the association of adsorbed collector ions into two-dimensional aggregates, called hemi-micelles.9 Subsequently, the rapid increase in flotation rate of quartz was shown to coincide with hemi-micelle formation." We would like to discuss briefly the concept of hemi-micelles in terms of recent interpretations of micelles in bulk solution. Micelle hypothesis: In dilute solutions, alkyl ammonium and related salts behave as ordinary strong electrolytes, but at a certain concentration there is a marked change in physical properties of the solutions, e.g., in equivalent conductance, transport number, freezing point lowering and viscosity. To account for these phenomena, McBainl1 introduced the concept of micelles, which are aggregates of long-chain ions. It is believed that the ionic heads of the constituent ions of the micelle are in contact with water, whereas the nonpolar groups turn away from it and are in contact with each other. Work must be done to bring these charged polar groups together, but energy is gained (i.e., so called van der Waals cohesive energy) when hydrocarbon chains are expelled from the water and allowed to associate. For a given polar group, the tendency to form micelles will therefore strongly depend on the hydrocarbon chain length. Theoretical treatments of micelle formation by Shinoda12 and Phillips13 and others lead to the following expression for the concentration at which micelles form (the critical micelle concentration or cmc) in aqueous solutions of long- chain electrolytes

Jan 1, 1964

By John Sasadi, Karl Heinz Zepter, Leonard Sugin, Roger L. Hulette

Mt. Newman Mining Co. is now completing an expansion program, begun even before initial construction was complete, which will result in the ability to ship up to 35 million tpy of iron ore by early 1973. Located in the Pilbara region of Western Australia, the mine at Mt. Whaleback is about 700 road miles north of Perth and 265 railroad miles south of the port facilities at Port Hedland. Development of the tertiary crushing and screening facilities best illustrates the orderly, but rapid, sequence through which the capacity of the port loading terminal has been expanded. When the present program is completed, crushing and shiploading capability will reach - - 35 million tpy. Operations commenced in 1969 with 3 crusher lines in service; and despite the 5-million annual ton rating, 6.46 million tons of ore were shipped during the first full year of operation. With continuing increase in ore sales, expansion to an annual capacity of 12 million tons was authorized, and installation of two more crusher lines was begun. As a part of this program, provision for installation of a sixth crusher at some future date was included in the planning; but before construction was completed, new ore sales contracts demanded further expansion to an annual rate of 20 million tons, and the sixth crusher line was authorized. The distributing and collecting conveyors had been designed for extension in length and increase in capacity, therefore, conveyor service was provided for the additional crushers with additional belting and hardware only.

Jan 6, 1972

By Albert J. Phillips

As EARLY AS 1824, Haidinger1 described crystals of native copper that were, according to Dana,2 "probably twinned parallel to the octahedral plane and normal to this axis." In 1837, Rose3 very clearly demonstrated that native copper crystals were commonly twinned on the octahedral plane. Lasaulx,4 in 1882, described polysynthetic octahedral twins and stated that enclosed twinning lamellae were observed. Even on crystals formed artificially by electrolysis, twinning was observed as early as 1886, by Brown.5 Many other descriptions of twinning in native copper and in gold and silver are to be found in the literature, and in every case with which we are acquainted the twinning is conformable to the spinel law; i. e., the octahedral plane is both twinning and composition plane. Metallurgists have long been familiar with the straight-sided bars or bands that commonly occur within the irregularly outlined grains of metallic crystalline aggregates. They are certainly found in nearly all metals of the face-centered cubic type after cold working and annealing. If a specimen showing these bands is rotated, keeping the angle of incidence of the illuminating beam constant, they usually exchange color contrast periodically with their respective matrix crystals. Also slip lines, when produced in these specimens, nearly always show a change in direction upon passing through the bands, giving rise to the "stairway" effect often illustrated in metallurgical textbooks. Apparently the only quantitative observations on bands of this sort were made by Osmond and Cartaud6 on austenitic steel. They selected,

Jan 1, 1928

By Kenzo Ikeda

The Kosaka smelter is situated in the extreme northern end of Hondo (the main island of Japan) 15 mi. east of Odate, on the government railroad, to which it is connected by a private railway. It contains ten blast furnaces having a maximum daily capacity of 1600 short tons of ore, conducting a slow pyritic smelting entirely without coke or limestone, and with a charge carrying over 50 per cent. of briquetted and agglomerated fines. The matte (35 per cent. Cu) is blown in two basic-lined barrel converters, the blister copper (98.8 per cent. Cu) being cast at once into anodes. The adjoining refinery contains 600 tanks with a maximum capacity of 1300 tons of cathodes per month, the byproducts being gold, silver, and bismuth. At present, working at about half capacity, the whole plant consumes 2000 kw. of hydro-electric power, and employs 850 men and women. The ores are derived from two principal sources: The relatively new Hanaoka mine, 20 mi. from the smelter, yielding copper pyrites by underground mining, and the old Kosaka open-cut mine, 1 1/2 mi. from the smelter, yielding three different ores: (a) kuromono, a compact finegrained mixture of barite (32 per cent.), zinc blende, galena, and pyrite, the whole carrying about 2.5 per cent. Cu; (6) cupriferous pyrites with 2.4 per cent. Cu; (c) siliceous ore with 2 per cent. Cu. The Hanaoka ore now constitutes approximately one-half of the charge, almost replacing the Kosaka kuromono which was the ore chiefly smelted until 1913.'

Jan 1, 1923

By Kenzo Ikeda

The Kosaka smelter is situated in the extreme northern end of Hondo (the main island of Japan) 15 mi. east of Odate, on the government railroad, to which it is connected by a private railway. It contains ten blast furnaces having a maximum daily capacity of 1600 short tons of ore, conducting a slow pyritic smelting entirely without coke or limestone, and with a charge carrying over 50 per cent. of briquetted and agglomerated fines. The matte (35 per cent. Cu) is blown in two basic-lined barrel converters, the blister copper (98.8 per cent. Cu) being cast at once into anodes. The adjoining refinery contains 600 tanks with a maximum capacity of 1300 tons of cathodes per month, the byproducts being gold, silver, and bismuth. At present, working at about half capacity, the whole plant consumes 2000 kw. of hydro-electric power, and employs 850 men and women. The ores are derived from two principal sources: The relatively new Hanaoka mine, 20 mi. from the smelter, yielding copper pyrites by underground mining, and the old Kosaka open-cut mine, 1 1/2 mi. from the smelter, yielding three different ores: (a) kuromono, a compact finegrained mixture of barite (32 per cent.), zinc blende, galena, and pyrite, the whole carrying about 2.5 per cent. Cu; (6) cupriferous pyrites with 2.4 per cent. Cu; (c) siliceous ore with 2 per cent. Cu. The Hanaoka ore now constitutes approximately one-half of the charge, almost replacing the Kosaka kuromono which was the ore chiefly smelted until 1913.'

Jan 1, 1923

By A. C. Heath, E. H. Dix

The importance of aluminum-silicon alloys in thc light alloy field is now generally recognized. Where silicon was once considered detrimental to the properties of aluminum, useful alloys now contain as much as 13 per cent. Furthermore, silicon is present as an impurity in aluminum of even the purest grades. Iron is another important impurity in aluminum and likc silicon is found in small quantities in the purest aluminum available today. The manner of occurrence of iron and silicon in commercially pure aluminum and many of its alloys exerts a very pronounced influence upon their properties. The effect of large quantities of iron in aluminum-silicon alloys is so detrimental that it has been found necessary to limit the allowable maximum percentage to as low a figure as is consistent with quantity production and satisfactory physical properties. The intimate relation existing between iron and silicon in aluminurn and alurninum alloys makes necessary a more complete knowledge of this ternary system. This paper is divided into two principal parts, dealing respectively with aluminum-silicon solubility equilibria and the constitution of aluminum-iron-silicon alloys. Part I.—Aluminum-silicon Alloys The early work on this system was largely confined to determining the general form of thc diagram and in this respect the results are in good agreement. Briefly, alulninunl and silicon form a simple eutectifcrous series without compounds. Until recently the solid solubility of silicon in aluminum had not been accurately determined. Ipraenkell (1908) stated that aluminum will retain 0.5 per cent. silicon in solid solu-t'ion. Rosenhain, Archbutt and Hanson2 gave the maximum solubility as about 1.50 per cent. and added that "this solubility docs not appear

By H. A. Baumann, A. J. Rostosky

EVER since the first installation of wet-washing methods of coal preparation, the removal of the water added by the washing process has created serious technical and operating problems. The rapid development and widespread adoption of wet washing has necessitated a corresponding development of dewatering methods and equipment. The amount of water retained by coal varies with the size of the coal. The moisture that is largely on the surface of the particles is easily shaken off coarse coal; thus coarse coal can be dried comparatively easily and quickly. Fine coal presents a larger surface area than does coarse coal, so its capacity for retaining moisture is greater. In fine coal, moisture below about 5 per cent is held between the coal particles and its removal is difficult. Draining and drying of the finer sizes is a major problem at many washeries. Two common problems of coal-washing practice that are intimately connected with dewatering and drying are the clarification of washery water and the prevention of stream pollution. The first field has been studied from many angles, including the use of coagulating and settling agents followed by vacuum filters to remove the solids, and the use of sludge tanks with dewatering screens incorporated therein. In many districts, the disposal of sludges into streams has been stopped by law. The lack of space for impounding sludges has created problems of disposal in other districts. Reduction in moisture means a saving in freight costs as well as the elimination of difficulties in unloading and storing. Excess moisture in coal causes it to freeze in localities where severe climatic conditions pre¬vail. Excess water in coals to be used in the production of coke and manufactured gas has a chilling effect on the walls of the oven or retort. Dryness of coal is important in producing good briquettes.

Jan 1, 1943

By Christopher H. Bierbaum

The first significant fact observed in the study of bearing metals is that not a single pure homogeneous metal has given satisfactory service; all bearing metals are alloys made up of two or more phases; that is, they consist of hard and of relatively soft microscopic particles intimately mixed. The function of the hard particles, or bearing crystals, is to support the load and resist the wear when actual metallic contact exists between the bearing surfaces. The functions of the softer particles are to allow the harder particles to adjust themselves to the surface requireinents of the journal and to wear down slightly below the surface of the harder, forming slight depressions on the apparently smooth wearing surface of the bearing, in which some of the lubricant is held when the bearing surfaces are brought into contact with each other. It is this characteristic of certain alloys to form these slight depressions, and thus provide the means for retaining a lubricant, that characterizes them as true bearing metals; in fact, a bearing metal has been defined as "an alloy that is capable of retaining a lubricant upon a bearing surface."' The extent to which the lubricant can be so held determines the most valuable characteristic of an alloy as a bearing metal. An alloy which, perhaps, most characteristically represents a bearing metal is the composition of copper and tin that contains sufficient tin to produce the tin-copper eutectoid, or delta crystal. The depressions worn upon the surfaces of the softer crystals of the teeth of a motor-truck worm wheel, made of an ll-per cent. tin bronze, in many cases were from 5 to 6 microns in depth; all other conditions remaining constant, this depth of wear increases with an increase of working pressure. This copper-tin bronze contains intercrystalline shrinkage cavities, which also

Jan 1, 1923

By Christopher H. Bierbaum

The first significant fact observed in the study of bearing metals is that not a single pure homogeneous metal has given satisfactory service; all bearing metals are alloys made up of two or more phases; that is, they consist of hard and of relatively soft microscopic particles intimately mixed. The function of the hard particles, or bearing crystals, is to support the load and resist the wear when actual metallic contact exists between the bearing surfaces. The functions of the softer particles are to allow the harder particles to adjust themselves to the surface requireinents of the journal and to wear down slightly below the surface of the harder, forming slight depressions on the apparently smooth wearing surface of the bearing, in which some of the lubricant is held when the bearing surfaces are brought into contact with each other. It is this characteristic of certain alloys to form these slight depressions, and thus provide the means for retaining a lubricant, that characterizes them as true bearing metals; in fact, a bearing metal has been defined as "an alloy that is capable of retaining a lubricant upon a bearing surface."' The extent to which the lubricant can be so held determines the most valuable characteristic of an alloy as a bearing metal. An alloy which, perhaps, most characteristically represents a bearing metal is the composition of copper and tin that contains sufficient tin to produce the tin-copper eutectoid, or delta crystal. The depressions worn upon the surfaces of the softer crystals of the teeth of a motor-truck worm wheel, made of an ll-per cent. tin bronze, in many cases were from 5 to 6 microns in depth; all other conditions remaining constant, this depth of wear increases with an increase of working pressure. This copper-tin bronze contains intercrystalline shrinkage cavities, which also

Jan 1, 1923

By Bradley Stoughton, Henry M. Howe

This paper presents an experimental verification of some of the predictions made by one of us1 concerning the influence of certain conditions of casting upon the size and position of the pipe, and the position of the segregate, in steel ingots. The predictions which we have been able to verify are the following: A. That the pipe is shortened and the segregate raised: 1. By slow casting; 2. By casting with the large end up instead of down; 3. By retarding the cooling of the top, e.g., by means of a sinking-head. B. That the pipe is shortened by slow cooling. C. That the pipe and segregate lie in the last-freezing part. Our procedure was to cast ingots of wax (commercially pure stearic acid) containing a little bright green copper oleate (usually 1.5 per cent.) under varying conditions; to saw each ingot open along a longitudinal plane passing through its axis; and to examine the longitudinal section thus laid bare. In order to make the segregate or enriched part more distinct in color from the impoverished part, a very little red cerasine was added. An experiment which will be described later showed that the cerasine itself does not segregate markedly, if at all. Hence we may assume that the strong contrasts between the green and red shown in so many of our ingots are due, not to segregation of cerasine, but to that of the green oleate, in the wax which in itself is uniformly reddened with cerasine.

Jan 1, 1908

By C. A. Heiland

For a long time it has been known that it is possible to deduce conclusions about the physical constitution of the interior of the earth from the records of natural earthquakes obtained by stationary seismographs. In view of this fact it is surprising how late, relatively speaking, geologic prospecting by seismic methods has been taken up, although the first suggestion was made 40 years ago—that travel-time curves of artificial explosions might be used for the study of the change of the velocity of seismic waves as depth. Further suggestions of practical applications of artificial explosions for geologic purposes were made by Belar12 by von dem Borne,3 by Benndorf and by Galitzin,5 but it was not .until 1919 that Mintrop obtained a patent on the seismic prospecting method which he has applied commercially on a large scale ever since. Dr. Mintrop came to this country with his method at about 1923. Since that time, several American oil companies have developed seismographs of the mechanical type for the vertical component similar to that of Mintrop's (Humble Oil Co., Dr. Ricker). Other consulting geophysical companies designed other types of seismic devices, the simplest of them for the recording of the first impulse being the geophone (McCol-lum Geophone Co.). The galvanometric recording method as first proposed by Galitzin is being used (Geophysical Research Corpn.?) and use is being made even of the piezoelectric properties of crystals for portable seismographs (F. Rieber). There is such an enormous variety of all kinds of portable seismographs, vibrographs, accelerographs, etc., that it is difficult to decide just what kind is preferable. Unfortunately, nothing has been published as yet about American designs of portable seismographs, except the Wood-Anderson torsion-seismometer. After Mintrop's design of portable seismographs, other constructions were made

Jan 1, 1929

By Auguste J. Rossi

We cannot expect, within the limits of this paper, to treat this subject exhaustively, but will endeavor, in the following, to present it in as concise a manner as is consistent with a clear exposition of its importance. Ores of titanium, titaniferous iron-ores (that is, iron-ores containing a notable amount of titanic acid, TiO2,, say not less than 5 per cent., generally 10 to 20 per cent., and frequently more, up to 40 per cent. or thereabout), occur all over the world in immense quantity, " in mountain masses," constituting in some localities, as in Sweden, Norway, Canada, the Adirondacks (N. Y.), in North Carolina and other States of the Union, the geological formation itself, the igneous rocks having, in many places, been so permeated with the metallic oxides as to justify their being called iron-ores. As a rule they are Bessemer ores, quite free from phosphorus and sulphur, though not invariably so. When the percentage of titanic acid is very high, that of the iron is low, but the proportions do not necessarily vary in the same ratio; that is, a rich ore may contain more titanic acid than one lower in iron. The percentage of iron varies, being as low as 35 to 36 per cent. in real ilmenite. It is more generally not less than 50 to 55 per cent., reaching often an average of 58 to 60 per cent., and as high as 63 to 65 per cent. It is obvious that if these ores were to be considered in the same light as other iron-ores, equally rich in iron, they would form an excellent stock for blast-furnaces for years to come, as their supply might be called inexhaustible, and they could

Jan 1, 1903

By Karl Sundberg

ElectRical investigations carried out in regions containing sedimentary rocks showed that sediments generally are good electrical conductors, a fact which at the present time is used for structural investigations by electrical methods. It is of fundamental importance, not only for these investigations but also for electrical prospecting in general, to know the electrical properties of various soils and rocks. It will be useful, therefore, to discuss this question with the hope that the general points of view discussed in this paper will perhaps be completed by further observations and determinations of material from various localities. This paper is based principally on the study of literature, and the purpose is primarily a discussion of the main factors that determine the electrical conductivity of soils and rocks. It will follow, however, that the factors discussed here also frequently decide how far a certain orebody can be regarded as a good electrical conductor compared with the surrounding rocks. All rocks are more or less porous, and the pores are filled with liquids and gases. Their electrical conductivity, therefore, depends on the following factors: 1. The electrical conductivity of minerals composing the rock. 2. Electrical conductivity of the liquid filling the pores. 3. Proportion of the volume of liquid filling pores of the rocks to the solid rock material. 4. Shape of the pores. 5. Arrangement of the particles of gas and liquids. 6. Temperature. Dry minerals, with the exception of certain ore minerals, are complete nonconductors from the point of view of applied geophysics; in the present investigation we deal with rocks which have no conducting minerals, and factor 1, therefore, is not important. The same is true of soils. The liquids contained in soils and rocks in most cases are waters, sometimes oil. As oil is a nonconductor of electricity, the impregnating waters will determine the electrical conductivity of soils and rocks.

Jan 1, 1932

By Robert Pike

THE first authentic description of an iron bath for the deposition of iron is probably that of Bottger in 1846, who used a bath containing ferrous sulfate and ammonium chloride. In 1861, Kramer deposited iron from ferrous chloride solution. Electrolytic iron was produced in 1.869 by Bietz, who used it for making some magnetic tests. In the same year, Klein is said to have worked out his process. Jacobi1 in 1869 described the results obtained in electroplating with iron on copper for making dies and plates for bank notes, by Klein's process. A letter from Klein to Jacobi describes the bath more fully. It consisted of FeSO4 + (NH4)2S04. Lenz2 described ?some properties of electrolytically precipitated iron. He used Klein's bath, FeSO4 + MgSO4 + MgCO3, to neutralize and obtained fine-grained and hard iron. His conclusions were as follows: 1. Electrolytic iron and copper contain gases, notably hydrogen. 2. The volume of gas absorbed by iron varies within wide limits, but it is easy for iron to take up very considerable quantities of gas. 3. The absorption of gas is principally in the first formed layers of iron. 4. When iron is heated, gas begins to come off below 100°, principally hydrogen. 5. Heated to redness, reduced iron oxidizes in water, in part at least at the expense of the oxygen of the water, decomposing it and setting free hydrogen, which is partly or wholly absorbed. Siemens,3 in 1889, was the first to propose a general process embodying a step for leaching a sulfide mineral with ferric chloride or sulfate and a step for regenerating the leach and depositing iron on a cathode in a diaphragm cell. So far as is known, Siemens did not carry out his patent

Jan 1, 1930

By David W. Brunton

Mine-drainage and the ever-increasing demand for water on the plains have within the past few years necessitated the driving of a great number of adits and tunnels, including many of considerable size and great length. In most instances, existing conditions have called for extreme rapidity of execution; and this necessity, coupled with the high altitudes at which most of the work has been carried on, excessive freight-rates, and difficulty of access, has involved many complex and interesting problems. One of the most rapidly executed undertakings of this class is the Laramie tunnel, recently completed for the Laramie-Poudre Reservoirs & Irrigation Co. This tunnel is driven through Green ridge, a spur of the Continental Divide, which separates the Laramie river from the Cache-la-Poudre in Laramie county, Colo. Green ridge is extremely persistent, and further northward in Wyoming is known as Sherman hill, the highest point on the Union Pacific railway. At the point where the tunnel is driven, two opposing bends bring these streams within 2.5 miles of each other, with a difference in elevation of 500 ft. The rock exposed on the banks of the two rivers does not differ materially in hardness; and, without a geological study of the conditions involved, it would appear that the difference in the depth of erosion of the two streams is due principally to the greater volume of water at this point in the Cache-la-Poudre, which has a drainage-area above the tunnel-portal of 110 sq. miles, as against 30 sq. miles of natural drainage for the Laramie. To increase the water-supply at the tunnel, however, this latter amount has been augmented by two side collection-canals, which bring the available drainage-area up to 84 square miles. The nearest railroad shipping-point to the eastern portal is

Jan 1, 1913

CHUQUICAMATA, as the Chile Copper Company's mine is known, has the largest developed deposit of copper ore in the world. Indeed, it is improbable that its equal will ever be found. The Union Miniére du Haut Katanga, operating in the Belgian Congo, may some day surpass Chuquicamata in the total amount of copper produced; or one of the companies developing the rich copper region of Northern Rhodesia may ultimately outdo it. But in each instance, the ore will come from a group of mines separated by 80 miles or more; whereas the deposit at Chuquicamata is one vast integral mass containing as a minimum probably 1,000,000,000 tons of ore, averaging better than 8.5 per cent copper, and as a maximum-well, most any reasonable figure might err on the low side. Utah Copper approaches Chuquicamata more nearly than any other in tonnage of exploitable ore; but Utah's ore is less than half as rich. The figure for the aggregate copper content of the reasonably assured ore at Chuquicamata is breath-taking at 50,000,000,000 pounds. Other distinctions has Chuquicamata: It was the first of the Porphyry Coppers to use leaching as the method of treating the ore; its plant cost for producing is lower than that of any of the others, only Braden and Utah being close rivals; and it was worked for its copper long before any of the others. According to an authentic article published in Ingeniería Internacional (May, v 1982) the Incas smelted copper ores from Chuquicamata prior to 1536. Diego de ALnagro, to whom Charles V, King of Spain, generously allotted a one-fourth portion of South America lying south of Cuzco, the Inca metropolis, made an expedition into Chile in 1534. Better known to history, perhaps, is Pizarro, who was awarded the area immediately north, and who proceeded

Jan 1, 1933