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By Robert A. Rapp

The standard molar free energy of formation of MOO,was determined between 750o to 1050o C in galvanic cell measurements involving the solid electrolyte Zr0.85 Ca0.15 O1.85. Use of the reference electrodes Fe + FexO and Ni + NiO Provided two independent determinations of FoMoo2. The data may be represented by the equation FMoO2 = -137,500 +40.0T(°K) which is in good agreement with previous CO/CO, gas equilibrium measurements of Gleiser and Chipman. The standard molar free energy of formation of molybdenum dioxide has recently been reported over a large range of high temperatures from the calorimetric experiments of King, Weller, and christensen.' Gleiser and chipman2 have also recently determined ?FmoO2 from 926o to 1068oC in CO/CO2 gas equilibrium measurements. Earlier gas equilibrium studies have been made and reviewed by Gokcen.' Over the temperature range studied by Gleiser and Chipman their values for ?FoMoO2 differed from the calorimetric data by about 700 cal. This investigation was undertaken to resolve this difference and thereby establish the two phase mixture of Mo + MOO, as an electrode of well-known oxygen potential for galvanic cell applications at very high temperatures. The galvanic cell technique involving the Zr,.,, Ca,0.15 01.85 solid electrolyte was introduced for the

Jan 1, 1963

By H. L. Bilhartz, H. F. Dunlap, C. R. Bailey, Ellis Shuler

Data are presented which indicate that the saturation exponent, n, in the equation, R. = R100S-11, relating core resistivity, I:,. to the resistivity at 100 per cent saturation. R100. and to the saturation, S. may vary appreciably from the value of two which is usually assumed for this exponent when interpret ing well logs. Values ranging from one to two and one-half have been found on (.ore sample investigated to date. Attempts to correlate this saturation exponent with porosity or permeability of the core have not been successful. The saturation exponent is apparently not a function of the interfacial tension between the brine and the displacing fluid. Some evidence is given indicating that the resistance of the core is not a unique function of the saturation but depends upon the manner in which this saturation was achieved. Equipment and technique are discussed for measurement of resistivities in core plugs in which water saturation can be varied. lNTRODUCTION A number of investigations of the resistivity-saturation relationship for un-c~~nsolidated sands and consolidated (.ore samples have been reported in the literature. According to most of these: R. = R¹ººS², where R² = the resistivity of a formation at saturation S, and R¹ºº= the resistivity of the formation at 100 per cent water saturation. Much of this work was (lone on unconsolidated sands desaturated by gas or oil. Hen-clerson and Ynster worked exclusively with dynamic systems, flowing oil or gas through consolidated cores. There is some doubt as to how well this reproduces static reservoir conditions. Jakosky and Hopper³ onsidered also the case of consolidated core plugs, but the oil-water distribution in the emulsions which they used to saturate their cores is almost certainly different from that occurring in reservoirs. Recently Guyod quotes the results of some Russian work which indicates that n may vary from 1.7 to 4.3. No experimental details of this work are available. In connection with electric log interpretation it is important to know the value of the saturation exponent. For example, if in a given reservoir it is found that the resistivity is three time.; the resistivity observed when the reservoir is 100 pel. cent 'saturated with water, this fact would be interpreted as indicating a water saturation of 33 per cent if the saturation exponent were 1 and a water saturation of 6-1 per cent if the saturation exponent were 2.5. EXPERIMENTAL METHOD In the work to be described it was assumed that reservoir conditions are most nearly obtained when core plugs are desaturated by the capillary pressure technique referred to in numerous places in the literature, as for example. in Bruce and Welge's paper.' In this technique the core. saturated 100 per cent with brine, is placed in contact with a ceramic disc permeable to brine but not to the displacing medium for the displacement pressures used. Pres-ure is then applied to the displacing medium and brine forced out of the core through the ceramic disc. Fig. 1 shows the core plug in place in the cell in which resistivity and saturation measurements are made. Fig. 2 shows the schematic electrical diagram wed to make resistivity measurements on the core plug. A four-electrode type circuit is used, employing a Hewlett-Packard model 400A. AC vacnum tube voltmeter. The 60-cycle AC current througli the core is adjusted to 1 milliampere and measured by noting the voltage drop across the calibrated 100-ohm resistor. The vo1tages appearing at probes 1, 2, 3, and 4 are then successively measured. Voltage drops across the top, center, and bottom portions of the core are obtained by sublracting the voltages appearing at successive probes. This technique avoids any polarization or other high contact resistance phenomena which may develop at the current input electrodes. Resistances which may develop between the core and the probes, and which are small compared to the 1-megoam input impedance 01' the vacuum tube voltmeter will (obviously not affect the measurements allpreciably. Any very appreciable resistallces which may develop at any of the probe wires are detected and allowed for by inserting a 1-megohm resistor in series with the voltage measuring probe. If the probe resistance is actually zero, the new voltage measured after insertion of the I-megolim resistor will be approximately one-half of that previously measured. since the input impedance of the vacuum tube voltmeter is itself 1 megohm. If an! appreciable probe resistance has developed, the new voltage is found to be appreciably greater than one-half of the previously measured voltage. Such probe resistance; have been found to develop only occasionally and usually can be traced to poor connections betwern the core

Jan 1, 1949

By C. R. Bailey, H. F. Dunlap, Ellis Shuler, H. L. Bilhartz

Data are presented which indicate that the saturation exponent, n, in the equation, R. = R100S-11, relating core resistivity, I:,. to the resistivity at 100 per cent saturation. R100. and to the saturation, S. may vary appreciably from the value of two which is usually assumed for this exponent when interpret ing well logs. Values ranging from one to two and one-half have been found on (.ore sample investigated to date. Attempts to correlate this saturation exponent with porosity or permeability of the core have not been successful. The saturation exponent is apparently not a function of the interfacial tension between the brine and the displacing fluid. Some evidence is given indicating that the resistance of the core is not a unique function of the saturation but depends upon the manner in which this saturation was achieved. Equipment and technique are discussed for measurement of resistivities in core plugs in which water saturation can be varied. lNTRODUCTION A number of investigations of the resistivity-saturation relationship for un-c~~nsolidated sands and consolidated (.ore samples have been reported in the literature. According to most of these: R. = R¹ººS², where R² = the resistivity of a formation at saturation S, and R¹ºº= the resistivity of the formation at 100 per cent water saturation. Much of this work was (lone on unconsolidated sands desaturated by gas or oil. Hen-clerson and Ynster worked exclusively with dynamic systems, flowing oil or gas through consolidated cores. There is some doubt as to how well this reproduces static reservoir conditions. Jakosky and Hopper³ onsidered also the case of consolidated core plugs, but the oil-water distribution in the emulsions which they used to saturate their cores is almost certainly different from that occurring in reservoirs. Recently Guyod quotes the results of some Russian work which indicates that n may vary from 1.7 to 4.3. No experimental details of this work are available. In connection with electric log interpretation it is important to know the value of the saturation exponent. For example, if in a given reservoir it is found that the resistivity is three time.; the resistivity observed when the reservoir is 100 pel. cent 'saturated with water, this fact would be interpreted as indicating a water saturation of 33 per cent if the saturation exponent were 1 and a water saturation of 6-1 per cent if the saturation exponent were 2.5. EXPERIMENTAL METHOD In the work to be described it was assumed that reservoir conditions are most nearly obtained when core plugs are desaturated by the capillary pressure technique referred to in numerous places in the literature, as for example. in Bruce and Welge's paper.' In this technique the core. saturated 100 per cent with brine, is placed in contact with a ceramic disc permeable to brine but not to the displacing medium for the displacement pressures used. Pres-ure is then applied to the displacing medium and brine forced out of the core through the ceramic disc. Fig. 1 shows the core plug in place in the cell in which resistivity and saturation measurements are made. Fig. 2 shows the schematic electrical diagram wed to make resistivity measurements on the core plug. A four-electrode type circuit is used, employing a Hewlett-Packard model 400A. AC vacnum tube voltmeter. The 60-cycle AC current througli the core is adjusted to 1 milliampere and measured by noting the voltage drop across the calibrated 100-ohm resistor. The vo1tages appearing at probes 1, 2, 3, and 4 are then successively measured. Voltage drops across the top, center, and bottom portions of the core are obtained by sublracting the voltages appearing at successive probes. This technique avoids any polarization or other high contact resistance phenomena which may develop at the current input electrodes. Resistances which may develop between the core and the probes, and which are small compared to the 1-megoam input impedance 01' the vacuum tube voltmeter will (obviously not affect the measurements allpreciably. Any very appreciable resistallces which may develop at any of the probe wires are detected and allowed for by inserting a 1-megohm resistor in series with the voltage measuring probe. If the probe resistance is actually zero, the new voltage measured after insertion of the I-megolim resistor will be approximately one-half of that previously measured. since the input impedance of the vacuum tube voltmeter is itself 1 megohm. If an! appreciable probe resistance has developed, the new voltage is found to be appreciably greater than one-half of the previously measured voltage. Such probe resistance; have been found to develop only occasionally and usually can be traced to poor connections betwern the core

Jan 1, 1949

By George Smith

ChillaQoe is situated in latitude 17" S., about 138 miles from the port of Cairns, with which it is now connected by rail. A township has been established on the banks of Chillagoe creek, a perennial stream of irregular volume crossing the field almost at rightrangles, nearly midway between the mining-camps of Calcifer and Mungana, which have been formed at the southeastern and western extremes of the field respectively. This situation was selected because of the water-supply and its proximity to the site most suitable for the erection of reductionworks. By its central position it commands the whole of the mines. The altitude above sea-level is about 1200 ft., whereas that of Calcifer and Mungana is 1400 ft.—a difference sufficient to account for a materially higher temperature at Chillagoe. The surrounding limestone bluffis add by radiation to the heat, and, at the same time, prevent the cool breezes from passing freely through the town; consequently, the temper* ture, which is high throughout the year, and especially so during the summer months, is here ge~ierally very oppressive also. The general trend of the field is southeast and northwest, and its length about 18 miles, with an average width of 5 miles; the approximate area is thus 90 sq. miles. The surrounding mineral-district is, however, much more extensive, and numerous other mines, sprcad over wide areas and producing a variety of minerals, exist in the same or parallel belts of mineralized country, of which Chillagoe proper covers but a very small portion. Immense bluffs of limestone, wollastonite and conglomerate, rising in places to nearly 300 ft., and so~netimes nearly a quarter-mile across, give the field a very picturesque and interesting appearance. The limestone has been classified as Devo-

Jan 1, 1904

By Roy E. Dickerson, W. M. O Connor

The production of crude petroleum of the Bacuranao field, Cuba, fell off rapidly because no new wells Mere drilled. In December 1938, the total was 15 bbl. per day. The estimated average from this serpentine field for the year is 20 bbl. per day. The Motembo area produced an estimated average of 160 bbl. per day. Production in July was 215,946 gal of gasoline, or 165 bbl. per day. In August production was higher because a new well in the concession, the Luisa Marcela, produced 189 drums the first day and required pit storage. The Atlantic Refining Company of Cuba started a deep test upon a long, narrow, surface-defined anticline 3 km. south of Remedios, a town on the north coastal plain of Santa Clara province, in December 1938. The Atlantic Refining Co. is doing extensive seismograph arid gravity-meter work in Matanzas arid Santa Clara provinces. The Shell company was rigging for a deep test in western Havana province at a location about 2 km. west of the town San Antonio dc los Banos New Petroleum Law More serious attention was given by some of the major oil companies to the development of petroleum in Cuba as a, result of the passage of a Petroleum Law ill that country on May 9, 1938. Under the old mining lam of Cuba, which gave no special treatment to petroleum, the usual provisions giving reasonably satisfartory guarantees to encourage investmerit of foreign capital were either entirely lacking or were 30 ambiguously expressed as to require legislative action. Under the new law, Government royalty is fixed at 10 per cent with the provision that it will be reduced to 9 per cent on crude petroleum that is refined in Cuba. Royalty to the surface owner is 1 per cent. A surface tax on a sliding scale from 10¢ to 406 per hectare per year is applicable to all exploitation concessions granted under the law or adapted to its provisions. So export tax is payable upon petroleum. Stability of taxation

Jan 1, 1939

By W. M. O Connor, Roy E. Dickerson

The production of crude petroleum of the Bacuranao field, Cuba, fell off rapidly because no new wells Mere drilled. In December 1938, the total was 15 bbl. per day. The estimated average from this serpentine field for the year is 20 bbl. per day. The Motembo area produced an estimated average of 160 bbl. per day. Production in July was 215,946 gal of gasoline, or 165 bbl. per day. In August production was higher because a new well in the concession, the Luisa Marcela, produced 189 drums the first day and required pit storage. The Atlantic Refining Company of Cuba started a deep test upon a long, narrow, surface-defined anticline 3 km. south of Remedios, a town on the north coastal plain of Santa Clara province, in December 1938. The Atlantic Refining Co. is doing extensive seismograph arid gravity-meter work in Matanzas arid Santa Clara provinces. The Shell company was rigging for a deep test in western Havana province at a location about 2 km. west of the town San Antonio dc los Banos New Petroleum Law More serious attention was given by some of the major oil companies to the development of petroleum in Cuba as a, result of the passage of a Petroleum Law ill that country on May 9, 1938. Under the old mining lam of Cuba, which gave no special treatment to petroleum, the usual provisions giving reasonably satisfartory guarantees to encourage investmerit of foreign capital were either entirely lacking or were 30 ambiguously expressed as to require legislative action. Under the new law, Government royalty is fixed at 10 per cent with the provision that it will be reduced to 9 per cent on crude petroleum that is refined in Cuba. Royalty to the surface owner is 1 per cent. A surface tax on a sliding scale from 10¢ to 406 per hectare per year is applicable to all exploitation concessions granted under the law or adapted to its provisions. So export tax is payable upon petroleum. Stability of taxation

Jan 1, 1939

By K. G. Davis, P. Fryzuk

A study has been made of the effect of undercooling on the grain structure and solute distribution in small ingots of pure bismuth and of a 100 ppm Ag in bismuth alloy. Autoradiographic evidence shows that in undercooled melts a network of dendrites is formed throughout the melt immediately after nu-cleation. At large undercoolings the dendrites are very thin and closely spaced. The origin of the observed grain morphology can be explained on the basis of information about the mode of solidification revealed by the impurity substructure. WHILE a great number of studies of nucleation in undercooled molten metals have been made, comparatively little attention has been given to the mode of solidification from melts with large undercool- ings. Colligan and Bayles1 and Walker2 have measured the rate of advance of the solid-liquid interface in undercooled nickel melts, but the morphology of the solidifying material remained a matter of speculation. Fehling and Scheil3 have described the grain structure in ingots formed from undercooled melts of nickel, palladium, and copper, and a series of Ni-Cu and Ni-Pd alloys. At small undercoolings, equiaxed structures are observed, the grain diameter tending to increase as the temperature of nucleation is lowered. At greater undercoolings, a columnar structure is developed, while with still further undercooling there is a smaller grain size incorporating rather coarse subgrains. All-bright and Colligan4 examined the grain structure shown by ingots solidified from melts of nickel and of Ni-Ag alloy at an undercooling of 105°C, and concluded that considerable grain growth had taken place after solidification. The object of the present work is to correlate the mode of solidification from undercooled melts with both the grain structure and impurity segregation, using tracers to examine the latter.

Jan 1, 1965

By William Kelly, Frederick Laist

The slow, tedious and costly method of reducing copper matte to metallic copper in the reverberatory furnace, commonly known as the Welsh process, was displaced by the rapid and inexpensive converter process about fifty years ago. The art of refining copper was for many generations a carefully guarded secret among the Welsh furnacemen and was handed down among them from father to son. An attempt was made to apply it at Butte when the smelting of copper ore first started there but it proved too difficult and expensive under local conditions, and until the introduction of the converter process the entire output of copper was shipped to Swansea in the form of high-grade (60 per cent) matte. Before the construction of the Manhes converter, attempts had been made to reduce copper matte in the bessemer steel converter, but these failed, chiefly because the air was blown through the bottom of the vessel. The air holes became clogged with chilled copper as soon as the reduction started. Manhes partially overcame this difficulty by placing the tuyeres in the side of the vessel, some, distance above the bottom, thus allowing space beneath them for the copper to accumulate. Nevertheless the first attempts to operate such a converter at Butte were not successful, as no means had been provided for clearing away obstructions, which formed to some extent in front of the tuyeres. This difficulty was overcome by drilling holes in the outside wall of the air chamber directly opposite the holes in the shell and lining, so that these could be punched

Jan 1, 1934

By C. R. Kyle, R. L. Perrine

A transparent model of a reservoir has been used to study some characteristics of instability in miscible displacement. The linear model dimensions are 1/4 in. x 91/2 in. x 10 ft. The model is packed with spherical glass beads. Thee groups of experiments have been performed. The objectives were to measure, respectively, the rate of growth of the transition zone, flow velocity variations in the transition zone, and the effect of a graded viscosity zone on stability. All experiments were compared, where possible, with theory. The transition zone grew almost linearly with distance traveled, regardless of flow rate, where adverse viscosity ratios were used. At very adverse viscosity ratios and large distances traveled, some reduction below linear growth was noted. This could be attributed to the effects of mixing. General similarity in flow pattern was commonly shown in different tests, although exceptions occurred at the higher viscosity ratios. Injection of tracer spots permitted direct experimental measurement of velocity variations. Statistical methods were used to compare observed velocity variations with recently published theories. Surprisingly good agreement with some theoretical predictions was obtained. In the experiments using an initially graded viscosity zone, macroscopic stability was reached before predicted by theory. Under conditions theoretically considered to be slightly unstable, any fingering tendency was too slight to become observable within a 10-ft long system. The general correlation of all experiments with published theory was good, and suggests that theoretical predictions can be extended to reservoir problems. INTRODUCTION Early laboratory studies of miscible displacement demonstrated the high recovery efficiency possible with this method. Linear laboratory models showed that, under some circumstances, all in-place hydrocarbons could be recovered using as little solvent as 5 per cent of the pore volume. These results led to a series of pilot field projects. Under realistic conditions, however, other laboratory studies showed that a small solvent bank may not recover much more oil than a conventional gas drive. The cause of this lack of efficiency is unstable viscous fingering. The size of the solvent bank required to give optimum recovery is, therefore, a question of great economic significance. The object of the experiments described in this paper was the quantitative measurement of unstable flow parameters, the verification of present theories on the miscible displacement process, and correlation of these theories with ex peri mental observation. Of the theories which have been advanced, those by Dougherty, Koval and Perrine show promise of predicting reservoir performance with reasonable accuracy.l-7 The present experiments were correlated, where possible, with the theories of Koval and Perrine. Dougherty's theory was not used because of the additional computational difficulty it presented and the belief that no further information would result. EXPERIMENTAL EQUIPMENT A transparent reservoir model, consisting of a vertical reinforced plexiglass column, was used for the experiments. The column was packed with glass beads, which served as the porous medium. To induce a known velocity disturbance in the flow, a double cosine wave restriction in the transverse cross-section was placed at the top of the column. To mark the flow field and provide a means of measuring the local fluid velocity, a dye-spot injection system was provided. The column was 10 ft high by 1/2 in. wide by 1/4 in. deep. The cosine restriction was placed 16 in. from the top of the column. The glass beads were smooth and spherical and had a mean diameter of 0.0102 cm. Liquids entered the top of the column through a manifold allowing three points of entry (left, center, and right, or any combination of these). A positive-displacement pump with variable-speed drive was used to control liquid flow rates. The pump transferred viscous oil from a reservoir to an accumulator, which displaced the test liquid into

Jan 1, 1966

By John S. Alexander

THE typical block coal of the Brazil (Indiana) District differs in chemical composition but little from the coking coals of Western Pennsylvania. The physical difference, however, is quite marked ; the latter has a cuboid structure made up of bibuminous particles lying against each other, so that under the action of heat fusion through- out the mass readily takes place, while block coal is formed of alternate layem of rich bituminous matter and a charcoal-like substance, which is not only very slow of combustion, but so retards the transmission of heat that agglutination is prevented, and the coal burns away layer by layer, retaining its form until consumed. This property permits the use of raw block con1 in the furnace but theo-

Jan 1, 1876

By John S. Alexander

The typical block coal of the Brazil (Indiana) District differs in chemical composition but little from the coking coals of Western Pennsylvania. The physical difference, however, is quite marked; the latter has a cuboid structure made up of bituminous particles lying against each other, so that under the action of heat fusion throughout the mass readily takes place, while block coal is formed of alternate layers of rich bituminous matter and a charcoal-like substance, which is not only very slow of combustion, but so retards the transmission of heat that agglutination is prevented, and the coal burns away layer by layer, retaining its form until consumed. This property permits the use of raw block coal in the furnace but theo-

By W. M. Hirthe, E. H. Greener, D. R. McCann

It has been proposed1'2 that, at low temperatures, point defects are a strengthening factor in inter-metallic compounds whereas, at high temperatures, the deformation is diffusion-controlled and, therefore, an increase in the concentration of point defects tends to soften or increase the plasticity of a compound. More recent investigations, including those of Bloem and Kroger' on PbS, Kramers and smith4 on TiO, and Nadeau5 on LiF, have extended this concept to ionic crystals. Rutile (TiO2) is a tetragonal transition metal oxide which has a defect structure over at least the compositional range. The defect in near-stoichiometric rutile is either an oxygen ion vacancys or a titanium ion interstitial.' This investigation does not contribute to resolving the defect question but either defect would satisfy the results obtained. Six specimens having the same orientation, see Fig., 1, utilized in an independent investigation1' were cut with a diamond saw from a single-crystal boule purchased from the Linde Co. Three specimens were annealed in air at 1200°C for 4 hr and slowly cooled to room temperature in a period of 12 hr. The remaining specimens were reduced in a vacuum of l0 mm Hg at 1200°C for 4 hr and cooled at the same rate in vacuum. The reduced specimens were weighed before and after reduction and, assuming the weight loss to be oxygen, the corresponding oxygen-to-metal ratio is 1.998. All specimens were chemically polished and etched utilizing the techniques described by Hirthe, Adsit, and Brittain." The specimens were embedded in acrylic resin and mounted on a leveling vise in a Kentron micro-hardness tester. A 200-g load was applied to a Knoop indenter with a descent time of 18 sec and a dwell time of 20 sec. Eight indentations were made on a near (171) surface, approximately 3 deg from the (lii) plane, for each orientation of the major axis of the indenter relative to the crystal structure. The dependence of microhardness on orienta-

Jan 1, 1963

By R. W. Raymond

The tidings of Mr. Hewitt's death, cabled to me at Rome, Italy, brought me a great shock as well as a sincere sorrow. I had left him, a few weeks before, not indeed in vigorous health, but still quite able to command recognition as a continued power in public affairs; and I thought him destined to enjoy for many years that final stage of a long, active and honored career, in which, having passed beyond the struggles and rivalries of business and of politics, his life and character could be justly appreciated by all men, like some noble work of art, already crowned, and marked henceforward "hors de concours." Moreover, he was, and would be to the end, not merely the passive recipient of admiration and esteem, but the source of iuspiring appeals, effective warnings and wise counsel. His rich and varied experience he had placed at the service of his fellows. His lightest word was weighty, and those who contradiEted him only injured their own cause thereby. Great trusts (true " trusts," in the old and proper sense of the term), like the Cooper Union, the Carnegie Institution, and others, still commanded his disinterested services. Great principles of liberty and of justice continued to be reinforced in perilous crises by his powerful advocacy; great measures were daily receiving from him a decisive impetus. No wonder it seemed to. us that this happy period of reward so well earned, and of beneacence so welcome to innumerable recipients of its blessing, must continue yet awhile. We did not expect the night instailtly to engulf the full-orbed sun. Nor, indeed, has this been our experience; in this instance, the sunset has left an afterglow more luminous than many a noonday. For the principal data contained in the following brief sketch of Mr. Hewitt's life, I rely upon memoranda personally approved by hirn, some months before his death, for my use in

Jan 1, 1904

By W. A. Griffith

The fundamental principles and modern techniques of experimental planning and data analysis, applicable to any type of research, are particularly important in flotation experimentation. Since they constitute the modern science of experimentation, they should be among the working tools of any scientist, research engineer, or plant operator engaged in flotation investigates. This chapter is a review of these principles and techniques. Equipment and procedures for the actual conduct of experiments will not be discussed here since these subjects are well covered elsewhere in this volume. Neither will any attempt be made to impart a working knowledge of statistical methods of data analysis since this would be impossible in the space allotted, and many excellent texts are available to the diligent inestigator.1-4 The objective here is simply to interest the reader in the application of statistical techniques to flotation experimentation by illustrating their utility in situations frequently encountered, and to point out the principles of experimental planning necessary for their proper use. Any conscientious metallurgist engaged in flotation experimentation or operations is well aware of the inherent complexity of the flotation process, and of the often frustrating difficulties this introduces into experimentation. The raw materials normally treated by the process are complex both physi- cally and chemically, and often highly variable even when from the same source. The flotation process itself is characterized by a very large number of potentially important process variables. Many of these are beyond the con- trol of the metallurgist, and some cannot even be measured quantitatively with available instruments. Those which can be measured and controlled with reasonable precision often produce effects which are intricately interrelated. Not only are the variables many, but the physical and chemical mechanisms by which they function are imperfectly under stood. To compound the difficulty, experimental techniques are relatively crude. Controls are not very precise, and the human factor looms large in most flotation experiments. These situations lead inevitably to experimental data of a relatively low degree of precision or reproducibility. Some are inclined to think that these conditions are unique to flotation experimentation. They are not. The experimental problems met by the agronomist, the biologist, the social scientist, and others are equally complex. Investigators in these fields pioneered in the development of methods for handling just such situations by proper experimental planning and the application of statistical methods in the analysis of data. Their pioneering work has grown into a well established modern science of experimentation which has spread into every field of science. This science is based upon statistical

Jan 1, 1962

By C. G. Dunn

Identification of the kinds of orientation relationships that may exist among crystals is an important problem in the metallurgical field. As an aid to its solution standard orientations of several orders of twins would be very useful for rapid analyses to discover high-order as well as low-order twin relationships. Although data have been published that give orientations for three generations of twins, these data are not readily useful in the form presented; i.e., in a stereo-graphic projection with one pole per orientation.' However, accurate data based on calculations of the positions of all {1001 planes for such groups would be very useful when presented in tabular form. Therefore, calculations have been made for a group of four orders of twins and the data are listed in Table 3. Illustrative applications are considered briefly, with the idea of pointing out what may be done with large groups of orientations. Method of Computing Orientation OF a Twin It is common practice to describe the orientation of a crystal in terms of the positions on a stereographic net of the poles of certain planes of the crystal. A single position on a net may be given in terms of two angle variables, two sets of which appear in the following equations: Polar Net Wulff Net x = , sin ?p cos Fbp x = r COS ?w y = r sin ?p sin Fp y = r sin ?w cos Fw % = r cos ?p z = r sin ?w, sin +, The three numbers z, y and z determine a length r as well as a direction (0, 4) in an X, Y, Z coordinate system. In the present case, r will be set equal to (h2 + k2 + L2)1/2, where h, k and I are the usual Miller indices for a crystallographic plane, a restriction that facilitates determination of the positions of poles of new planes from those of old or known ones,2 as will become evident later. Furthermore, since twinned lattices have certain planes in common, it is an easy matter to determine the orientation of a twin of a crystal if the orientation of the crystal itself is known. We start therefore with a crystal of known orientation (positions of three {Ioo} poles given) and determine where the cube poles occur in first, second, third and fourth-order twins. Methods for identifying twinned lattices and for making the calculations to find the orientation of a twin have been published.3,4' Reference 4 will be illustrated in the calculation of the orientation of a twin, even though this method differs from the one used by the writer in obtaining the following data on four orders of twins. Consider a crystal S and its twin A1, A' being one of the four {112} or {III} type* first-order twills of S. The orientation of S—i.e., the positions of poles of (I00)

Jan 1, 1945

By Don Blackmar

THE production of non-ferrous secondary metals has become a large and important industry in the United States, and deals with practically every type of manufacturing concern.. Its business is unique in that it generally buys from its customers as well as sells to them, whether they are individuals, cities, corporations, or the United States government. Its operations are of vital importance to the success and prosperity of many of the nation's most important manufacturers; yet there are few industries about which less is generally known by those outside it, whether concerning the magnitude of its operations or the details of its actual technique. The industry itself is to blame for this meager publicity, because its technical men have made few attempts to openly exchange ideas, in spite of the excellent examples set by the iron and-steel or the copper and brass industries. Whether this is due to the ancient shroud of secrecy generally supposed to cover smelting operations, or because its technical men actually felt that the industry was too puny to be interesting, is hard to say. This paper will consider its subject in a 'general way, attempting to show something of the size and importance of the industry, as well as its fitness to do its work well. Attention will be called to the sound economic reasons for the handling of non-ferrous wastes by specialists, and to the often unseen losses of metals and labor which occur when manufacturers reclaim' their own metallic wastes.

Jan 1, 1928

By John Hays Hammond

This is an era of " expansion; and, conformably with the change in commercial conditions, the function of the mining engineer, as well as that of his confreres in many other professions, has also expanded. From the position of an engineer, limited to the determination of technical questions, the engineer of to-day has come to assume an economic importance in those branches of industry dependent upon engineering skill for their development. He is indeed an engineer of limited usefulness who does not go further professionally than to submit a purely technical report on subjects presented for his consideration. While he has the same responsibility as formerly in the solution of the technical problems involved, he is further expected to supplement his report with advice on the financial and commercial aspects of these problems. For the great majority of problems presented to the engineer ultimately involve the determination of the pecuniary, relations of the propositions under consideration. The great corporation lawyer no longer earns his fee by merely submitting his opinion as to the legal issues involved in law-suits affecting the corporation; he now assumes charge of the entire legal work, including both the organization of the corporation and the maintenance of its legal status thereafter. In like manner, the engineer, whose report was, as I have said, formerly confined to the determination of the geological and other cognate features of a mining enterprise, is now expected, not. only to embody information on these subjects in his report, but also to give his opinion whether the property offered for sale in pursuance of such an enterprise is worth the price asked for it. Moreover, if he recommends the purchase of a property, he incurs a certain moral responsibility for its efficient manage-

Nov 1, 1908

By J. M. Roberts, D. M. Barnett

The activation energy required to break a pinned dislocation line away from its condensed atmosphere of impurity atoms is calculated as a .function of applied stress, without neglecting line tension. Reasows are presented for not assuming the effect of line tension to be negligible when considering the problem of freeing a small segment of dislocation from an impurity atmosphere. The dislocation is considered to he pinned at each atomic size along its length and the pinning points are assumzed immobile. The development is a refinement of the origznal cottrell-bilby1 theory. The solution is compared to recent approximations developed by cottrell3 and Haasen5 in which line tension con- IN 1949 Cottrell and bilby1 considered the problem of determining the force required to pull a dislocation away from its condensed atmosphere of impurity atoms. They also examined the effect of thermal fluctuations on this force. The dislocation line was pictured as bowing out in a triangular loop under the action of an applied stress, and the activation energy necessary to free the dislocation from its atmosphere was calculated as a function of stress, line energy, and dislocation-solute atom interaction. siderations were neglected. A qualitative explanation of the yielding process in terms of the activation of Frank-Read sources is presented, but the lack of a realistic solution to the dynamic dislocation problem involved prevents an extension of the model at present. A self-consistent correlation between the present calculations and experimental data for delay time associated with yielding and the temperature dependence of the upper yield stress was made. Favorable agreement was noted. It is concluded that extension of the original Cottrell-~ilby' theory which includes line tension effects can just as well describe the yielding process as other approximations3,5 which neglect line tension. Cottrell and Bilby found the form of the activation energy vs stress curves to be almost independent of the line energy and the interaction energy (i.e., these parameters only affected the activation energy U by a scale factor). A check of the theory was accomplished by comparison with the experimental data of McAdam and Mebs2 for the lower yield stress as a function of temperature. cottrell,3 in 1957, attempted to obtain a simple closed-form solution for the activation energy as a function of stress by linearizing the quartic equation relating displacement of the dislocation line and applied stress. It was argued that since the contribution to the line energy/atomic plane of a dislocation is made by the long-range stress field of the dislocation through a term of the type (Gb3/2p)ln A/ro, where

Jan 1, 1963

FRED TURRELL GREENE Fred Turrell Greene was born in Brooklyn, N. Y., Nov. 22, 1872. His father, William A. Greene, was born in Providence, R. I., and his mother, Angenora Semlear, was born in Brooklyn, N. Y. Fred's early school clays were spent in Boston, whence his father moved to Canada in 1882. Attending first the Collegiate Institute in Toronto, .then the High School at Berlin (now Kitchener), Ontario, where he graduated, Fred progressed to the Toronto University and the Michigan College of Mines, at Houghton, where lie graduated in 1897. He secured employment almost immediately at Butte with the engineering force of the Boston & Montana Consolidated Silver Mining Co., under Chas. S. Batterman. In 1899 he went to Rossland, B. C., where he spent more than a year as mining engineer and assistant superintendent of the War Eagle Consolidated Mining and Development Co. and the Center Star Mining Company Ltd. Returning to Butte in 1900, he acted as assistant geologist for the Anaconda Copper Mining Co. until 1906, when he filled a similar position in St. Paul with the Great Northern Railway for about two years. From 1908 until his tragic death on Christmas day, 1917, his headquarters were in Butte, where he enjoyed an excellent reputation -as consulting mining engineer, with a rapidly widening circle of clients. During the past four years he had been consulting engineer for the Elm Orlu and other mines controlled by Hon. W. A. Clark, and was in charge of underground developments and law-suit preparations for the celebrated apex case between the Elm Orlu and the Butte & Superior companies. At the time of his death he was in charge of similar work for the Utah Metals Co., in connection with their mines at Bingham, Utah. He was also for some years active in the Coeur d'Alenes, as consulting geologist for the Federal and other companies there, and was considered an authority on this as well as the Butte district. Mr. Greene was unmarried, and is survived by his parents, a younger brother, who is in the army, and one sister, Mrs. James A. Hatch, of New York. Some of the most important and valuable ideas regarding the nature and origin of copper ores have originated in Butte, since that district is not only one of the greatest examples of mineralization known in any land, but has gone through a long course of mining litigation, and was, one of the first to be studied intensively by geologists. In connection with the early investigations, as well as with the most recent in that camp, Mr. Greene played an important part. His conscientious devotion to his duties and his intelligent handling of the problems presented for solution sufficiently explain the esteem in which he was held by his employers and his professional associates.

Jan 5, 1918

By Walter E. Duncan, Oscar F. Tangel, A. M. Gaudin, Franklin Dewey, R. A. Johnson

Xanthates have been used as collectors of sulfide minerals in the concentration of ores by flotation for over a decade, yet much remains to be done to elucidate the underlying reasons for the remarkable effectiveness of these compounds in this connection. Briefly stated, the known facts concerning the effect of these reagents on the floatability of minerals are as follows: 1. Xanthates are without effect on silicates, silica, and generally on minerals currently regarded as "gangues." 2. Xanthates in very small amount increase enormously the floatability of sulfides of copper, lead, silver, iron and mercury. 3. If zinc sulfides are first '(activated," as by treatment with a copper salt, they are readily floated by xanthates; otherwise not. 4. Elemental copper, silver and gold have their floatabilities increased by xanthates. 5. Sulfides of elements that are not typically metallic—e.g., stibnite, realgar, molybdenit—are not made to float markedly better by treatment with xanthates. 6. Oxidized minerals of lead and copper are floated if treated with large amounts of xanthates, but not so if treated with amounts of the same order of magnitude as required for sulfide flotation. Oxidized zinc minerals are not floated unless xanthates having unusually long hydrocarbon chains (e.g., eight carbon atoms or more) are used. Iron oxides and carbonate are not floated by xanthates. From a flotation standpoint the most striking feature about xanthates is the very small amount required to accomplish startling changes in the behavior of some minerals. The amounts used in practice to effect excellent concentration are frequently of the order of 0.05 lb, of agent per ton of ore; that is, of the order of one part of agent per forty thousand parts of ore. Changes in amount of agent of the order of 0.01 lb. per ton of ore (or 0.002 lb. per ton of pulp, on a 4:l basis) have marked effects on the metallurgical results obtained. Yet these changes represent a variation of but one part per million parts of pulp.

Jan 1, 1935