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By Louise Barton Freeman, Iley B. Browning, Coleman D. Hunter

During 1942, production of oil in Kentucky reached a total of 4,169,163 bbl. of which 1,807,809 bbl. came from eastern Kentucky. This was more than a million barrels less than in 1941, owing partly to the low price of crude oil, which almost eliminated wildcatting, and partly to spacing regulations, which limited the number of wells drilled in small, shallow pools where the pressures are not sufficient to maintain maximum recovery in widely spaced wells. In eastern Kentucky much of the oil was produced from outliers of the Mauch Chunk series at the disconformable contact of the Mississippian and Pennsylvanian. Although wells producing from this horizon, known as the Maxon, are sprinkled over the entire area, the greatest concentrations are in Martin, Floyd, Knott and Pike Counties. A new 30 to 40-bbl. well has been completed in this formation in ,Pike County, where the carbon ratio is so high that ordinarily oil would not be expected. Pike County is one of the largest producers of Maxon gas, and the offset well to this oil well produced gas. Of the 412 gas wells drilled in Pike County, 12.2 per cent produced gas from the Maxon horizon. During 1942, the old Menifee " Cornif-erous" field, the Mariba-Denniston field, was redrilled between old wells, and although it did not produce any large amount of oil it did contribute 2018 bbl. In the oldest oil field in eastern Kentucky, the Ragland pool, operators are cleaning out abandoned wells and are using this oil for fuel oil. There is a possibility that some of this may be used in the future as distilled fuel oil. Eight wells were completed in 1942 in the Jackson County gas field. The development of Jackson County, which was started in 1934 and in which commercial quantities of gas were encountered at a depth of 1100 to 1200 ft., has become of importance in 1942 with the completion of eight wells, making a total of 24 commercial producing wells with an average rock pressure of 140 lb. At this time the gas is not being marketed. In the last year it has been found that these wells, which produce from the Niagaran dolomite ("Cornif-erous"), respond to acidizing and the production has been thus greatly increased. There has been less development in Estill and Lee Counties than for several years. Two wells were drilled in Greenup County, one of which had a show of oil in the Berea sandstone. One deep test, drilled by the Owens-Libbey-Owens Co. in Lawrence County, was dry. This well was drilled to a depth of 4975 ft. into the top of the Clinton shale sequence. Of the 202 wells completed in Floyd, Martin, Knott and Pike Counties, 187 were gas wells, 3 oil wells and 12 dry holes. In Floyd County 66 per cent of the gas production was from the Devonian-Mis-sissippian black shales, 53 per cent in Martin, 79 per cent in Knott and 65 per cent in Pike. This is probably the largest continuous gas field east of the Mississippi

Jan 1, 1943

ASIDE from the John Fritz Medal, in which the Institute participates through its representation on the John Fritz Medal Board, the Institute itself has three major awards to make annually and one special prize for excellence in technical papers, as follows: The Robert W. Hunt Medal and- Prize, The J. E. Johnson, Jr., Award, the James Douglas Medal, and The Lewisohn Platinum Prize to senior members. ROBERT W. HUNT MEDAL AND PRIZE The partners of Robert. W. Hunt established a fund which was presented to the Institute at a fitting ceremony on May 27, 1920, to establish an annual medal and a sum of money to be awarded under the following rules: 1. The award shall consist of two prizes; first of a gold medal, second of a sum of money; a certificate to accompany each prize. The money prize shall not be awarded to a member over 40 years of age, but under unusual circumstances, both prizes may be allotted to one person provided that he is not over 40 years of age. In general it will be understood that the Committee shall award the money prize to the younger men, rather than the medal. 2. The awards shall be made not oftener than once a year to that person or persons contributing to the Institute the best on al paper or papers on iron and steel. The scope of the term "iron and steel" shall determined by the sub-committee considering the awards. In general, papers dealing with the practical side of the subject have preference over those dealing with the theoretical side in recognition of the fact that Captain Hunt's main contributions to the industry have been in the improvement of production and quality of material. 3. A sub-committee of three to five, including the Chairman of the Iron and Steel Committee, shall be appointed by the Iron and Steel Committee annually to adjudge the award subject to approval. 4. The awarding committee shall submit its report to the Iron and Steel Committee at its October Meeting, and the award be certified to the Secretary of the Institute in time to permit the presentation to be made at the Annual Meeting of the Institute. 5. The recipient of the award shall be designated "The Hunt Medallist." This prize is administered by the Iron and Steel Committee. J. E. JOHNSON, JR., AWARD This award is made from' the income of a. fund of $3000 donated by Mrs. Margaret Hilles Johnson in memory of her husband, J. E. Johnson, Jr., who was a prominent engineer, author of two valuable volumes on iron blast-furnace construction and practise, vice-chairman of the Institute's Iron and Steel Committee, and a frequent contributor of papers. to the Institute's Transactions. This prize is administered by the Iron and Steel Committee. The intent of the donor is to encourage young men in creative work in branches of the metallurgy or manufacture of pig iron with which the professional activities of Mr. Johnson were chiefly concerned. The control of the fund and distribution of the awards having been vested in the Board of Directors of the Institute, this Board has made the following regulations concerning it:

Jan 1, 1925

By C. S. Smith, K. K. Ikeuye

In an earlier paper1 one of the authors called attention to the significance of the relative free energies of grain boundaries and interphase boundaries in alloys in determining the shape and distribution of micro-constituents. The ratio of the interphase and inter-crystalline boundary energies (that is, —?12, where ?12 is the energy of the interface between a crystal of phase 1 and a crystal of phase 2, and ?11 is the energy of the boundary between two crystals of phase 1) will be denoted by F. It is this ratio that determines, by the simple triangle of forces relation, the dihedral angle, ?, of phase 2 where it adjoins a boundary between two grains of phase 1. On a metallographic sample various angles are actually obtained because of the random orientation of the plane of observation, but the statistically most frequent angle is the true one. These basic principles were discussed in detail in the earlier paper. The experiments described below show the effect of both composition and temperature on ? and T for some alloys containing a liquid phase, and provide data on the rate of approach to the equilibrium angles in both solid and liquid phases. All the alloys were melted in a graphite crucible and cast into ingots 3/4 by 11/8 in. cross-section. Some of the aluminum alloys consisted of two immiscible liquids from which uniform castings could not be obtained. The amount of liquid phase varied locally to a considerable extent and the analyses were meaningless. Nevertheless, the composition of the liquid would not differ from that in an alloy of the intended gross composition, and the synthetic composition of the alloys was therefore used in considering the surface energy results. The ingots were given initial deformation by cold-rolling to 50 pct reduction, annealed, and given a second 50 pct reduction prior to cutting into small samples for heat treatment at the times and temperatures subsequently reported. The resulting micro-samples were carefully prepared metallographically and examined at magnifications of 650, 1280, or 2500. The objectives used were 21X, 0.40 NA (dry); 41X, 0.65 NA (dry); and 80X, 1.40 NA (oil emulsion). The appropriate angles were measured by rotation of the stage of a Bausch and Lomb metallograph to align the appropriate boundaries successively with a cross-hair in a micrometer eyepiece. About 250 angles were measured on each phase. Though the angles were read to 1°, the accuracy is probably not above 3°, because of uncertainty in setting the cross-hair tangent to the sometimes curved boundary. The corners of very small particles, particularly in early stages of adjustment after cold-rolling, were difficult to measure and the results were slightly dependent on the magnification used (compare Fig 1-C and 1-D). With particles of larger size and more nearly equilibrium shape, magnification made no difference (vide Fig 1-F and 1-G). The measured angles were grouped in 10° intervals (5° if ? was less than 20°) and plotted in bar

Jan 1, 1950

By Iley B. Browning, Louise Barton Freeman, Coleman D. Hunter

During 1942, production of oil in Kentucky reached a total of 4,169,163 bbl. of which 1,807,809 bbl. came from eastern Kentucky. This was more than a million barrels less than in 1941, owing partly to the low price of crude oil, which almost eliminated wildcatting, and partly to spacing regulations, which limited the number of wells drilled in small, shallow pools where the pressures are not sufficient to maintain maximum recovery in widely spaced wells. In eastern Kentucky much of the oil was produced from outliers of the Mauch Chunk series at the disconformable contact of the Mississippian and Pennsylvanian. Although wells producing from this horizon, known as the Maxon, are sprinkled over the entire area, the greatest concentrations are in Martin, Floyd, Knott and Pike Counties. A new 30 to 40-bbl. well has been completed in this formation in ,Pike County, where the carbon ratio is so high that ordinarily oil would not be expected. Pike County is one of the largest producers of Maxon gas, and the offset well to this oil well produced gas. Of the 412 gas wells drilled in Pike County, 12.2 per cent produced gas from the Maxon horizon. During 1942, the old Menifee " Cornif-erous" field, the Mariba-Denniston field, was redrilled between old wells, and although it did not produce any large amount of oil it did contribute 2018 bbl. In the oldest oil field in eastern Kentucky, the Ragland pool, operators are cleaning out abandoned wells and are using this oil for fuel oil. There is a possibility that some of this may be used in the future as distilled fuel oil. Eight wells were completed in 1942 in the Jackson County gas field. The development of Jackson County, which was started in 1934 and in which commercial quantities of gas were encountered at a depth of 1100 to 1200 ft., has become of importance in 1942 with the completion of eight wells, making a total of 24 commercial producing wells with an average rock pressure of 140 lb. At this time the gas is not being marketed. In the last year it has been found that these wells, which produce from the Niagaran dolomite ("Cornif-erous"), respond to acidizing and the production has been thus greatly increased. There has been less development in Estill and Lee Counties than for several years. Two wells were drilled in Greenup County, one of which had a show of oil in the Berea sandstone. One deep test, drilled by the Owens-Libbey-Owens Co. in Lawrence County, was dry. This well was drilled to a depth of 4975 ft. into the top of the Clinton shale sequence. Of the 202 wells completed in Floyd, Martin, Knott and Pike Counties, 187 were gas wells, 3 oil wells and 12 dry holes. In Floyd County 66 per cent of the gas production was from the Devonian-Mis-sissippian black shales, 53 per cent in Martin, 79 per cent in Knott and 65 per cent in Pike. This is probably the largest continuous gas field east of the Mississippi

Jan 1, 1943

• A new curriculum for combined liberal arts-engineering education has been announced by 6 middle western colleges. The plan involves three years of ;study at one of the 5 liberal arts colleges and two years and a summer of 'engineering work at Case; graduates receive both the A.B. and B.S. degrees. * A new kind of mining is being pioneered by a pest Virginia coal operator which enables four men to produce 800 tons of coal a day. The machine that makes this possible is a giant auger, 5 ft in diam and 100 ft long. Together with the carriage in which it is moved about, it weighs 60 tons. A mobile, but separate power plant of 1000 hp drives it. ' * The Sorel smelter, which will reduce Allard Lake titanium ores, will utilize five 6-electrode rectangular electric furnaces. Furnace hearth size will be about 18x50 ft, and the furnace will smelt about 300 tons of ore per day, producing 100 tons of iron and 130 tons of 70 pct Ti02 slag. The furnaces will be fed continuously by gravity from charge bins, and tap at intervals of 4 hr or more. Slag will be transferred to a high speed casting machine, using cast iron molds, then crushed for shipment to pigment producers. The iron will be treated to reduce its sulphur content to 0.03 to 0.05 pct, and then cast into small pigs or ingots for shipment to steel mills. • Flying of North Africa's first airborne mangetometer survey was completed this month, covering approximately 20,000 sq km in north central Tunisia for Gulf Exploration Co.'s program there. Mapping was completed in less than 30 days. •Yore than 9000 employees of 11 electric companies are enrolled in a 6-hr program that successfully informs workers on the principles of the American economic system. The course is given by the Middle West Service Co. which claims that before and after employee opinion polls show that the course instilled a better understanding of free enterprise and consequently a favorable response to it. •According to a report issued by the American Geological Institute there will be 2865 graduates in geology, including advanced degrees from U.S. colleges in 1950. This supply of geologists compares with requirements for 1278 at the professional and subprofessional levels. The report contains a detailed statistical study of the supply and demand situation for geologists in the 1949-50 period. •The dark cloud of over-production in the bituminous coal industry has a silver lining, according to Natural Resources Notes. Closing marginal mines, mostly strip and truck mines, will result in lower average costs and higher quality of the coal still produced. The producers that will then constitute the industry will be properly equipped and adequately financed to carry forward an intensive campaign to holdd and increase the markets for bituminous coal. •A light, compact, highly reliable blasting machine which does not rely for its effectiveness on the operator's skill is being tested by the Army Engineers. Operating under all climatic conditions from -65 to 125F, the 50-cap machine consists of a springwound do generator and is waterproof.

Jan 8, 1950

By D. R. de Fontaine

By computing the values of the resolved shear stress for a great many orientations of the tensile axis on all 12 (111) <110> slip systems, Taylor and Elam&apos; were able to map out a stereogram of slip systems, given here, Fig. 1, in Diehl&apos;s notation (see, for example Hauser and Jackson&apos;). The purpose of the present note is to derive such a stereogram by mathematical reasoning and to give a simple method of defining the system with highest resolved shear stress for any direction of the tensile axis, thereby eliminating tedious computation of the Schmid factor. Let the tensile axis, of direction cosines [xyz], make the angles 0 and relative to the slip plane normal [HKL] and the slip direction [hkl] respectively. Fig. 2 shows a simple cubic cell whose edges define a Cartesian coordinate system. Let A be a unit vector of origin 0 supported by the tensile axis. Its end point [xyz] then lies on a sphere of unit radius, on the positive hemisphere of which the planes z = 0, x = y, y = z limit the so called primitive triangle of a standard [loo] stereographic projection. For any point of this triangle, the following hold: 0«2 «y *sx « 1 [l] Now, for given [xpz], the most highly stressed system will be the one for which the following expression of the Schmid factor has the largest possible value: (HKL) belonging to the form (111) and [hkl] to the form <110>, the denominator on the right hand side of Eq. [2] is equal to 1.fi.a. The unknowns H, ... h, . . . can now be determined by correctly distributing +1 and -1 to H, K, L, and +1, -1,O to h,k, 1 giving the numerator of Eq. [2] its greatest positive value (the angles 0 and cpare chosen acute) subject to the condition: Hh+Kk+Ll = 0 [3] since the slip direction must lie in the slip plane. Condition [3] can be satisfied only by having one of its terms vanish and the other two equal to +1 and -1. Taking the case of the tensile axis lying in the primitive triangle, x2y, z and therefore Hh will be chosen equal to +1 with H = h = +1 in order to retain a maximum of + signs. There remain two alternatives: either 1 = 0 or k = 0. 1) take 2 = 0 Then Kk = -1 and the numerator of [2] becomes: Retaining a maximum of + signs gives L = k = +1 and becomes: 2) take k = 0 Then L1 = -1and, likewise, the numerator of [2] becomes: xz - z2 + xy + yz [5] But the difference [5] - [4] can be written: (y - z)(x+y +z) [6] positive or zero by virtue of [I]. If [6] is positive (y > z), then the largest possible value for the numerator of [2] for any xyz inside the primitive triangle is given by [5], i.e., for: That is to say, the active slip system corresponding to an orientat:~on of the tensile axis inside the primitive triangle is:

Jan 1, 1962

By Jon J. Connor, Richard J. Ebens

The trace element geochemistry of the cherty clay-rich carbonate residuum cover in much of southern Missouri and adjacent parts of Arkansas was investigated during the earl 1970&apos;s as part of a statewide geochemical survey of Missouri.1-8 The study was environmentally oriented and focused on the character of the "natural" geochemical environment of the state. A great deal of effort was made to collect samples that would represent the geochemical variability of the near-surface environment in an unbiased way. In general, this was accomplished by use of randomization procedures in both collection and analysis. Most of the sampling sites were selected randomly to prevent personal bias from entering into sample selection. In the laboratory, samples were analyzed in a randomized sequence to circumvent the effects of any systematic bias that may have entered into the laboratory procedures. Several residuum samples contained 1000 parts per million (ppm) or more of lead, zinc, and barium. All these samples were collected in Washington County in or near the barite district. The frequency distributions shown in [Fig. 1] indicate just how unusual the residuum in Washington County is with regard to these three metals and copper. The shaded parts of the histograms represent the samples from Washington County. The histograms are based on analyses of 141 samples from 38 localities scattered over the subcrop of the Cambrian and Ordovician formations of southern Missouri and northern Arkansas. Eight localities were selected randomly from over each of four bedrock units-Bonneterre dolomite; Potosi and Erninence dolomites; Roubidoux formation; and the Jefferson City, Powell, and Cotter dolomites. Six localities were selected randomly from over the Gasconade dolomite. The geochemical "background" for these elements in residuum is defined by samples from outside of Washington County (unshaded part of the histogram); lognormal distribution curves have been fitted to the corresponding parts of each histogram. Clearly, these lognormal models (curves) describe well the background distributions of zinc, barium, and copper. The background histogram of lead concentrations is notably skewed to the right compared to the model. Lognormal distribution curves were also fitted to the data on lead, copper, and zinc in the residuum of Washington County. No model was fitted for barium in Washington County because of the distinct bimodality in the data. All samples containing more than 1000 ppm were collected in the barite mining district and obviously reflect the elevated levels of barium in the district. The frequency distributions for Washington County are clearly anomalous with respect to the background data, those for lead, zinc, and barium being exceptionally so. The models for anomalous lead, zinc, and copper seem to fit reasonably well, although the scatters in the lead and zinc anomalies are considerably larger than the scatters in the corresponding background data. The copper anomaly, although probably real, is greatly subdued compared to that of lead and zinc. Also, it has a scatter similar to that of the copper background, rather than being enhanced like the scatters of the lead and zinc anomalies. On the basis of techniques described by Miesch,4 the chemical abundance of copper, lead, and zinc in residuum in

Jan 1, 1980

By E. Stamboliadis

Dithiophosphates are reaction products of phosphorous pentasulfide with various organic compounds such as phenols, alcohols, mercaptans, dioalcohols, amines, and nitrides. The products with alcohols are commercially known as "aerofloats" and these are investigated in this presentation. It appears that the formation of insoluble metal dithio phosphates is responsible for their collecting properties with minerals." In this aspect they are very similar to xanthates.3 The solubility of metal dithiophosphates depends on the number of carbon atoms in the organic chain of the corresponding alcohol. An empirical mathematical model is presented here. It allows one to predict the number of carbon atoms necessary to ensure that a certain metal dithiophosphate will form at a selected pH value of the water solution. The Nature of Dithiophosphates Dithiophosphoric acid is the product of the reaction of phosphorus pentasulfide with an alcohol, as shown in the following equation: [P2S3 + 4 ROH - 2 (RO)2 PS2H + H2S (1)] where R stands for a hydrocarbon chain. The acid so produced can be neutralized by a base to produce the corresponding salt as shown in the following: [(RO), PS2H + NH- (RO)2 PS, NH,. (2)] In this aspect dithiophosphates are similar to xanthates, the only difference being the substitution of the tetravalent carbon atom in the xanthate polar group by a pentavalent phosphorus atom in the dithiophosphate group. This difference implies at least two characteristics: (1) that there are two hydrocarbon chains associated with the polar group so that an increase in the number of carbons of the single chain is expected to have a pronounced effect on the flotation properties, and (2) that the bond between the sulfur and the central atom is stronger than in the xanthate group. This probably leads to a decrease in both the polarizability of the electronic cloud of the sulfur and the interaction with cations.3 However, what is lost in the dithiophosphates by having a weak polar group can be gained by an increase in the number of carbons as will be seen later. Taking into account the size of the atoms involved in a dithiophosphate molecule, as listed in Table 1, It is possible to draw an approximate diagram of its structure as shown in [Fig. 1]. It is assumed here that the length of the single hydrocarbon chain is equal to that of the corresponding alcohol. Preparation and Purification Acid dithiophosphates can be prepared, as previously mentioned, in accordance with Eq. 1. The rate of this reaction is too slow at room temperature and can be improved by increasing the temperature to about 60° or 80°C7 or by evacuating the system. In our investigation evacuation was performed by a water aspiration pump. The dithiophosphoric acid so produced is liquid and dissolves in the alcohol. At the end of the reaction the product is filtered from the remaining P2S3; and dissolved in petroleum ether. By blowing anhydrous ammonia gas into the ether phase the ammonium salt forms as a white precipitate and can be sepa-

Jan 1, 1977

By D. W. Fuerstenau

MEASUREMENT of zeta potentials is a useful tool to study the surface chemistry of minerals under flotation conditions.1,2 Because there is continued interest in this approach, the apparatus for obtaining zeta potentials of nonconducting solids by the streaming potential method is outlined here. Fig. 1 illustrates the streaming potential apparatus." The streaming potential cell or plug consists of two 24/40 standard ground joints (4) joined with a piece of pyrex tubing 60 mm long and 12 mm in diam (5). The electrodes are made of bright platinum disks 19 mm in diam and 1 mm thick through which 0.5-mm holes have been drilled (6). To the surface of each is welded a piece of 80-mesh platinum gauze. Each electrode is permanently mounted on the ends of the inner parts of the two standard joints by means of a platinum wire (7) which connects it to the tungsten seal at the end of the cell (8). For ease in cleaning and handling the apparatus, the streaming cell is fastened to the 500-ml reservoir flasks (1) by means of two 18/9 ball and socket joints (2). This particular arrangement permits passage of the solution in either direction through the plug of particles. Flow of solution can be stopped by a stopcock (3). One of the reservoir flasks has a large opening to permit insertion of either a thermometer or a pair of electrodes for measuring pH of solutions within the system. In making the experiments, the plug is filled with 48 to 65-mesh particles, but a layer of 28 to 35-mesh particles is placed at each electrode to prevent any of the finer particles from passing through holes in the electrodes. The assembled apparatus is shown schematically in Fig. 2. To eliminate CO2 from the solutions, all experiments are conducted in a nitrogen atmosphere. Nitrogen, used to drive solutions through the plug, is passed through a bottle of concentrated KOH solution to remove CO2 (9). A 9-liter ballast reservoir (10) is used to maintain a more nearly uniform pressure. A series of stopcocks controls the direction of flow nitrogen to the flasks (11). Tubes of as-carite prevent backflow of CO2 into the system (12). Driving pressure, which can be set at any desired value, is measured with either a water manometer (13) or a mercury manometer (14). Reservoir flasks have side arms for making pressure corrections for the difference in water levels in the flasks. Streaming potentials are measured by the circuit illustrated in Fig. 2. The electrodes from the plug are connected through mercury wells (15) to a reversing switch (16), which reverses the polarity of the electrodes depending on the direction of flow of solution through the plug. The streaming potential is measured with a Leeds and Northrup type K2 potentiometer (17). Proper choice of null instrument is important because Eq. 1 assumes that the current which escapes through the measuring instruments is negligible. An ordinary galvanometer cannot be used to determine the null point because

Jan 1, 1957

ASIDE from the John Fritz Medal, in which the Institute participates through its representation on the John Fritz Medal Board, the Institute itself has five major awards to make annually for excellence in technical papers, as follows: The Robert W. Hunt Medal and Prize, The J. E: Johnson, Jr. Award, The Lewisohn Platinum Prize to senior members, and the James Douglas Medal. ROBERT W. HUNT MEDAL AND PRIZE The partners of Robert W. Hunt established a fund which was presented to the Institute at a fitting ceremony on May 27, 1920, to&apos; establish an annual medal and a sum of money to be awarded under the following rules: 1. The award shall consist of two prizes; first of a gold medal, second of a sum of money; a certificate to accompany each prize. The money prize shall not be awarded to a member over 40 years of age, but under unusual circumstances, both prizes may be allotted to one person provided that he is not over 40 years of age. In general it will be understood that the Committee shall award the money prize to the younger men, rather than the medal. 2. The awards shall be made not oftener than once a year to that person or persons contributing to the Institute the best original paper or papers on iron and steel. The scope of the term" iron and steel" shall be determined by the sub-committee considering the awards. In general, papers dealing with the practical side of the subject have preference over those dealing with the theoretical side in recognition. of the fact that Captain Hunt&apos;s main contributions to the industry have been in the improvement of production and quality of material. 3. A sub-committee of three to five, including the Chairman of the Iron and Steel Committee, shall be appointed by the Iron and Steel Committee annually to adjudge the award subject to approval. 4. The awarding committee shall submit its report to the Iron and Steel Committee at its October Meeting, and the award be certified to the Secretary of the Institute in time to permit the presentation to be made at the Annual Meeting of the Institute. 5. The recipient of the award shall be ,designated "The Hunt Medallist." This prize is administered by the Iron and Steel Committee. J. E. JOHNSON, JR. AWARD This award is made from the income of a fund of $3000 donated by Mrs. Margaret Hilles Johnson in memory of her husband, J. E. Johnson, Jr., who was a prominent engineer, author of two valuable volumes on iron blast-furnace construction and practise, vice-chairman of the Institute&apos;s Iron and Steel Committee, and a frequent contributor of papers to the Institute&apos;s Transactions. This prize is administered by the Iron and Steel Committee. The intent of the donor is to encourage young men in creative work in branches of the metallurgy or manufacture of pig iron with which the professional activities of Mr. Johnson were chiefly concerned. The control of the fund and distribution of the awards having been vested in the Board of Directors of the Institute, this Board has made &apos;the following regulations concerning it:

Jan 1, 1925

By I. Fatt

Laboratory relative permeability data on reservoir rock are obtained on samples which are not subjected to overburden pressure during the permeability measurements. These data are then used for calculating the performance characteristics of reservoirs in which the rock is under the pressure of the overburden. Recent observations have shown that the permeability and porosity of reservoir sandstones are decreased by application of overburden pressure. These observations led us to a study of the effect of overburden pressure on the relative permeability characteristics of sandstones. A previous note from this laboratory1 showed that overburden pressure, simulated by applying hydraulic pressure to the outside of a plastic mounted core. caused a reduction in permeability of the core by as much as 50 per cent at 10,000 psig. In a multiphase fluid flow system, the relative permeability at a given saturation will change if the permeability or the effective permeability changes but not if both permeability and effective permeability change by the same ratio. The tests described in this note were made to determine the effect of overburden pressure on permeability and effective gas permeability in the gas-oil system. The gas-oil system was chosen because the available equipment was best suited for studying this system. The resultant data can be applied to other systems of interest because the gas permeability in the gas-oil system is the permeability of the nonwetting phase and, as such, is equivalent to the gas permeability in the gas-oil-water system and to the oil permeability in the oil-water system. EXPERIMENTAL METHOD Cylindrical test plugs, one in. in diameter and one in. long, were cut from sandstone core samples from three different reservoirs. After extraction in toluene, the plugs were mounted in Lucite by conventional core mounting methods.3 The core properties are given in the legend in Fig. 1. The mounted cores were machined to fit the apparatus shown in Fig 4. Air permeabilities as a function of overburden pressure were measured by connecting lines (1) and (2) to a conventional air permeameter. To measure porosity changes as a function of overburden pressure, the lines leading to (1) and (2) and the core were saturated with kerosene; line (1) was capped and a small bore precision calibrated pipet was connected to (2). Changes in pore volume of the core as overburden pressure was applied were noted by reading the amount of kerosene produced into the pipet. To correct for the change in volume of the lines inside the hydraulic cell as a function of pressure, a pressure-vs-volume run was made with a solid Lucite cylinder substituted for the core. The change in volume of the lines was about 10 per cent of the change in pore volume of the core. No correction was needed for the permeability measurements because there was no measurable pressure drop in the lines at the maximum overburden pressure. Relative gas permeabilities were measured by the stationary liquid method described by Osoba, et al.&apos; Gas saturations were obtained by allowing the kerosene from a kerosene saturated core to evaporate out. This procedure was followed

Jan 1, 1953

By W. M. Fox, D. P. Detwiler

IN the course of research on semiconducting inter-metallic compounds, it became necessary to obtain gallium metal of greater purity that that available commercially. Several methods were considered for further purification, including acid leaching,&apos; fractional crystallization,&apos; and zone-refining.3-5 The method of fractional crystallization was discarded as being equivalent to zone-refining in purification but inefficient in material and time. Both acid leaching and zone-refining were tried, and the method finally adopted is a combination of the two. The acid leaching technique has been reported&apos; to produce gallium in which no impurities are detectable spectroscopically. Although this method is very effective in removing oxides and surface contaminants, semiconducting material made of gallium subjected only to leaching indicated little reduction in the concentration of metallic impurities. Zone-refining, however, appears very effective in removing trace metallic impurities, but comparatively ineffective in removing the surface oxide film. Consequently, the method evolved consists of acid leaching to thoroughly clean the surface, followed by zone-refining to remove metallic impurities. The low melting point and relatively high thermal conductivity of gallium introduce some difficulty in maintaining frozen and molten zones in zone-refining. To accomplish this, it is found necessary to reduce the effective ambient temperature by circulating ice water in coils about the regions that are to be kept frozen, while heat is supplied to the molten regions by resistance coils. The power supplied to the heating coils is regulated by a constant-voltage transformer and a variable autotransformer. Both heating and cooling coils are mounted on a transite base. The gallium ingot is held in a closed pyrex tube sliding inside the heating and cooling coils, the reciprocating method of Tanenbaum et al. being employed to move the molten zones through the ingot at a rate of 2 in. per hr. This apparatus is shown in Fig. 1. The results of a spectroscopic analysis f a zone-refined ingot, as well as of the material as-received and after acid leaching, are shown in Table I. The ingot was 32 cm in length, and received 37 molten-zone passes, the molten zone being about 4 cm long. The only impurity found was lead, the following elements being reported also as checked but not found in the pure material: Al, Sb, As, Ba, Be, Bi, B, Cd, Ca, Cr, Co, Cb, Cu, Ge, Au, Fe, Mg, Mn, Mo, Ni, Pt, Si, Ag, Na, Sr, Sn, Te, Ti, W, V, Zn, and Zr. There thus appears no indication of pickup of Al, Mg, or Si from the pyrex boat as reported by Zimmerman&apos; in his fractional crystallization. Thus it appears that definite removal of lead from gallium occurs during the zone-refining process. It also may be concluded that a more sensitive analytical procedure than spectroscopy is required to evaluate quantitatively the purity of zone-refined metals. One such procedure which is proposed for use in the near future is the measurement of very low temperature resistivity. Although this will not identify the impurities present, it offers a very sensitive check of total impurity. Acknowledgment This work was supported by the Air Research and Development Command, United States Air Force.

Jan 1, 1956

By E. H. Crabtree, Neil S. Parker

The custom milling plant of the Eagle-Picher Mining and Smelting Co. is at Sahuarita, Arizona, approximately 20 miles south of Tucson. It is connected by a 2-mile railroad spur to the main line of the Southern Pacific Railroad between Tucson and Nogales. The capacity of the plant is 500 tons per day. The mill is conventional except perhaps in the rather wide variety of ores treated. These vary from straight copper ores, from which only one concentrate is produced, and lead-zinc or copper-zinc ores from which two concentrates are produced, to complex gold-silver-copper-lead-zinc ores, which require the simultaneous production of three or lour concentrates. Custom ores are received in lots varying in size from a few truckloads to several carloads. Similar ores, after crushing and sampling, may be commingled, or individual lots may be milled individually. The ores are first dumped either into one of two 200-ton railroad bins, or into one of the two 75-ton truck bins. From these bins the lot of ore is individually crushed in a 24 by 16-in. jaw crusher to 3-in. size, and then to ½-in. size in a 3-ft Symons shorthead crusher. After crushing to ½-in., the ore is conveyed to the automatic sampling plant. This consists of three Vezin samplers in series, each successively cutting out 10 pct, 10 pct and 5 pct of its feed. After No. I sampler, the material passes through a mixing barrel and is then crushed to -in. in a set of rolls before passing to No. 2 sampler. Between No. 2 and No. 3 samplers, the ore is again mixed in a mixing barrel. The final sample, consisting of one pound per ton of ore, is taken to the laboratory, where it is further crushed to 1/8-in. in a coffeemill, and then riffled down to the size required for grinding in a pulverizer. The capacity of the crushing and sampling plant is up to 100 tons per hour, depending upon the character of the ore. After sampling, the ore is stored in five ore-storage bins, consisting of four 200-ton bins and one 175-ton bin. Each of these bins is discharged by means of belt feeders and conveyor to the ball mills, so that ores may be composited for milling in any required ratio, or milled separately by themselves. Fine grinding is done in one 6 by 4-ft Allis-Chalmers ball mill and one 8-ft by 36-in. Hardinge mill. These two mills both discharge to one 54-in. Akins Simplex High weir classifier. The classifier sands can be returned to either or both mills, so that flexibility in grinding for different ores is easily obtained. Flotation equipment consists of four 66-in. Fagergren machines for copper-lead roughing and six similar machines for zinc roughing. Lead-copper bulk concentrate is cleaned and recleaned in eight No. 18-S Denver machines, and zinc concentrate is cleaned in three 66-in. Fager-grens. Copper-lead differential separation

Jan 1, 1949

By E. H. Edwards, J. Washburn

Zinc crystals were deformed in simple shear and it was found that anisotropic strain hardening occurred in which the inactive slip systems were hardened more than the active system. The formation of dislocation barriers by dislocation interaction was discussed as a possible explanation of the hardening of the latent systems. STRAIN hardening which accompanies slip in a metal crystal is not limited to the slip systems actively contributing to the plastic strain. There is also a strengthening of the latent slip systems which are crystallographically equivalent to the active system. In the case of aluminum deformed in tension, Taylor and Elam1 found that plastic flow on one set of octahedral planes caused either the same or a slightly greater hardening on an inactive set. Similar results have been obtained for crystals of a brass2 and of Cu-A1 solid solutions.3 Experiments by Rohm and Kochendorfer4 indicated that the hardening of the active system exceeded the hardening of any latent system for aluminum crystals deformed in shear. On the other hand, strain hardening in zinc and cadmium crystals tested in simple shear at —196°C was recently found to be greater in the latent than in the active slip direction." When the strain direction was shifted during testing to a direction 60" from the original, a higher stress was required for glide to continue than would have been needed for flow to proceed in the original direction. The relation between the hardening of active and latent systems must be complex, depending upon the relative orientations of the systems and upon the experimental techniques used to deform the crystal. A detailed knowledge of the hardening produced in latent systems would be valuable in choosing between possible dislocation models of the strain-hardening process. The experimental data now available are incomplete and even contradictory. The present study was undertaken to provide quantitative information regarding the relative amount of hardening of active and latent systems for a particularly simple case. Zinc crystals were deformed in simple shear along one of the three crystallographically equivalent directions [250], [1210], and [1120] in the slip plane, and the relative hardening produced in each of these directions was compared. Experimental Procedure and Results The single crystals of 99.99 pct purity zinc used in this investigation were grown from the melt in the form of 1 in. diam spheres. Shear specimens were acid-machined from the crystals by a method which has been described previously. The gage section of the test specimen was a cylinder having a height of 1/8 in. and a cross-sectional area of approximately 1/3 sq in. All specimens were machined with the axis of this cylindrical gage section aligned with the [0001] axis of the crystal. An innovation in the design of the shearing apparatus for these tests was the provision for a rapid shift in the direction of the applied stress from one slip direction to any other slip direction lying in the same slip plane. Fig. 1 shows a section through the specimen and shearing apparatus, and Fig. 2 is a

Jan 1, 1955

By N. A. McLeod

BALL wear in wet grinding mills has been the subject of considerable discussion in the last few years. Its importance to millmen is obvious in view of the fact that ball wear may cost from 2 to 4¢ per ton of ore for the more fortunate operators and many times this cost when a refractory ore must be reduced to a fine state of comminution. Consequently, any factual information that may be obtained on the nature of ball wear may be applied to introduce changes leading to lower ball consumption and therefore also to lower costs. In 1940, while employed with the Britannia Mining and Smelting Co., Britannia Beach, B.C., I had occasion to investigate factors that might affect ball consumption. We performed a number of tests, which will be briefly described. These tests originated as a result of changing from a 3 1/2-in. ball to a 2-in. ball of different type of manufacture and were motivated by the desire to obtain the best possible type of 2-in. ball. Our testing was helped by the fact that the company operated a one-ton electric furnace, so that it was quite easy to make steel changes. It should be emphasized at the beginning that these tests produced results that in their general application to milling should be interpreted qualitatively rather than quantitatively. As will be evident in the description of the method used in testing, the balls were subjected to an intermittent batch grinding treatment, which may have produced results in rate of steel wear that may not have an accurate correlation with steel consumption in full-scale mill operation. However, with this fixed and rather arbitrary method of testing, results were obtained that may be of some interest and may stimulate further work on this subject. Unfortunately, owing to pressure of war work, our tests, which we had intended to repeat on a continuous grinding operation, had to be discontinued. METHOD OF TESTING Tests were made in a small cylindrical mill, rotating at 72 r.p.m. Internal dimensions of the mill were 10 1/2-in. dia. by 9 in. The cylindrical inner surface was lined with rubber and the two ends were formed by steel plates. A charge of 2000 grams dry feed and 2000 c.c. of water was added every 2 hr., the mill being drained of pulp before the addition of each charge, by tilting and sluicing with water. The mill was run on afternoon and night shift for daily periods of about 15 hr. total grinding time, and each test lasted from 60 to 150 hr. This batch method of testing involved a higher average pulp temperature in the mill, which undoubtedly affected comparative results in some of the tests. HARDNESS OF BALL VS. WEAR In these tests, special "eutectoid" steel balls were used, some of which were chill-cast and quenched, some sand-cast and quenched, and some sand-cast and annealed to a dead soft condition. The results obtained, using as mill feed an ore containing considerable free quartz and

Jan 1, 1945

By C. E. Morris, S. R. Pollack

Current -vo1tage -temperature characteristics were studied for Al-A12O3-Al, Au structures. The oxide film was grown by gaseous oxidation in an 0, glow discharge. The electron-transfer mechanism was identified as tunneling and the barrier heights and thickness were determined. It was found that the barrier height at the parent aluminum-oxide interface is 1.5 ev and the built-in vloltage with an aluminum counter electrode is 0.35 v. The growth mechanism of the oxide is also discussed and it is suggested that Mott&apos;s theory is not applicable in describing the growth. Discrepancies were observed in the detailed comparison of tunneling theory, based on a trapezoidal model, with the data, and several possible explanations are discussed. THEORETICAL analyses of electron tunneling from one nonsuperconducting metal to another through an extremely thin insulating film have been presented.1-6 These calculations relate the current density, J, to the voltage, V, between the two metals, and to the temperature, T. The results of these calculations indicate that the magnitude of J and the detailed shape of the J-V characteristic will in general depend most strongly upon such properties of the insulating film as the thickness, the dielectric constant, and the structure of the electron energy barrier profile. The experimental results of many7-11 workers have corroborated the main features of these calcu- lations and have in fact been used to determine properties of the thin insulating film. It has been demonstrated, for example, that the tunneling current formulation of simmons4 is adequate to describe the observed J-V characteristic over approximately 10 orders of magnitude of current. Furthermore, from these observations and analyses, insight into the nature of the A1-A12O3 (thermally grown) interface region has been obtained.&apos;&apos; The temperature dependence of the tunnel current has also been studied and, although a self-consistent set of tunneling parameters can be chosen to describe these data at low voltages (i.e., <0.5 v), the tunneling parameters are different from those obtained from higher voltage (i.e., of the order of 1 to 5 v) measurements." We have measured the effect of temperature and voltage upon the tunnel current at higher applied voltages and find that the theory is inadequate to describe all of the effects reported here. A discussion of the origin of this inadequacy is presented following a description of the samples used for these experiments, and the experimental results. SAMPLE PREPARATION Metal-insulator-metal structures were fabricated in the following way. A 99.999 pct A1 charge was used to deposit, in vacuo, thirty films, 2000Å thick, onto a 1 by 2 in. glass substrate (7059 Corning glass). Prior to deposition the substrate was glow-discharged for final cleanup and then baked at 200°C for 2 hr at a pressure of 5 x 10-7 torr. The pressure during deposition of the metal films was 2 X 10-6 torr and the deposition rate was 50 to 100Å per

Jan 1, 1965

By E. W. Hart, W. R. Hibbard

The room temperature flow characteristics of a series of Cu-Cr alloys are found to be related to the amount and characteristics of the chromium-rich precipitate. The results are consistent with the theory of Fisher, Hart, and Pry, which considers the trapping to dislocation loops around precipitate particles. THE use of dispersed phases for hardening metals, particularly high temperature alloys, has been practiced for several years. Current theories describing the effects of dispersions on the basis of dislocation theory have been proposed by Mott and Nabarro.l-4 rowan," and Fisher, Hart, and Pry.8 These theories recently have been discussed by Hart,&apos; who pointed out that the experimental data available for comparison with theoretical calculations for overaged alloys are confined to studies by Gensamer, Pearsall, Pellini, and Low,8 Shaw, Sher-by, Starr, and Dorn,9 and some hitherto unpublished data on Cu-Cr alloys which will be described herein. Certain difficulties were associated with the interpretation of the first two studies. Gensamer, Pearsall, Pellini, and Low were concerned principally with interparticle spacing and did not document particle sizes. Shaw, Sherby, Starr, and Dorn included all the data in their report which was necessary for the theoretical evaluation, but their study is subject to some question1" due to difference in prior history of various specimens and due to systematic differences in particle characteristics" which appeared to be associated with differences in the magnification of their microscopic examination. The current study was undertaken to obtain critical data in a manner which avoids some of these limitations. Specimens of eight Cu-Cr alloys remaining from a previous investigation&apos;&apos; were available in the form of 100 mil sheet of the compositions shown in Table I. At 200 mil this material had been previously an- nealed ½ hr at 1000°C, water quenched, and cold rolled 50 pct. Samples were further cold rolled to a thickness of 20 mil for a total reduction of 90 pct. Sheet tensile specimens of standard geometry with a gage length 2½ in. long and 0.20 in. wide were machined from this sheet. These specimens were then annealed in a dried N2-H2 atmosphere for the times and temperatures indicated in Table I. This anneal served two purposes: 1—to obtain a fairly uniform and nearly constant grain size of 0.015 to 0.022 mm average diameter, and 2—to precipitate a fairly uniform, nearly spherical over-aged dispersion of essentially pure chromium. A typical microstructure illustrating the grain size and the uniformity of the dispersion is shown in Fig. 1. A typical dispersion illustrating the range of sizes and shapes of the particles is shown in Fig. 2. The tensile specimens were tested in the Instron equipment described in ref. 11 at room temperature at a strain rate of 0.04 in. per in. per min. Three tests were run on each alloy with sufficient repro-ducibility that a single true stress-true plastic strain curve could be drawn through the three sets of data for each alloy. Typical curves are shown in Fig. 3.

Jan 1, 1956

By P. Marier, T. R. Ingraham

When anhydrous cupric sulfate is heated in a stream of nonreactive gas, cupric oxysulfate is formed. When this reaction is complete, the cupric oxysulfate then decomposes to cupric oxide, which is the normal end product of reaction. The kinetics of each of these reactions has been studied using pellets prepared from finely divided cupric sulfate and from finely divided cupric oxysulfate. In each case, the reactant-product interface within the pellet is well-defined, and by normalizing the decrease in inter facial area with the weight fraction of the pellet decomposed it has been shown that the interface migrates into the pellet at a uniform rate at constant temperature. The activation energy estirnated for the decomposition of cupric sulfate is 57 ± 7 kcal per mole and that for cupric oxysulfate is 67 ± 8 kcal per mole. The rate of interfacial reaction is flow-sensitive, increasing with increasing flow of a sweep gas in the range from 50 to 2000 cu cm per min. The rate of decomposition is retarded by sulphur trioxide in the sweep gas. The relationship between sulfur trioxide Partial pressure and rate is consistent with the Langmuir Adsorption Isotherm governing the retention of sulfur trioxide in the interfacial layer. MOST of the work reported on the thermal decomposition of cupric sulfate and of cupric oxysulfate is related to the thermodynamics of the individual decompositions.&apos;-4 No information is available on the rates of the individual reactions, on their activation energies, or on the effects of gas flow or of partial pressure of sulfur trioxide on the reaction rates. Some dubious conclusions based on relative reaction rates have been drawn from studies on the oxidation of sulfides. For example, on the basis of the products observed in a quenched system, it has been suggested5" that, when copper sulfide is roasted, the cupric oxide which is formed arises from the decomposition of either cupric sulfate or cupric oxysulfate. This is very difficult to reconcile with the thermodynamics of the C-S-O System,3 which support the probability that both cuprous oxide and cupric oxide precede cupric oxysulfate and cupric sulfate in the sequence of products formed during the oxidation of cuprous sulfide. In this paper the individual sulfate decomposition reactions will be examined and suggestions will be advanced for the mechanism of reaction. This will be based on the effects on reaction rate of changes in interfacial area, flow rate, and back-pressure of sulfur trioxide. EXPERIMENTAL Materials. The copper source material used in all experiments was Fisher Certified Reagent Grade anhydrous cupric sulfate, for which the following analysis was supplied by the manufacturer: chloride, 0.002 pct; alkalies and earths, 0.2 pct; insoluble, 0.002 pct; iron, 0.020 pct. Cupric oxysulfate was prepared by roasting cupric sulfate for 48 hr, with frequent rabbling, in an open tray in a muffle furnace maintained at 725°C. At this temperature, cupric sulfate develops about 0.16 atm pressure of combined sulfur trioxide, sulfur dioxide, and oxygen. Cupric oxysulfate develops only about 0.05 atm pressure, and is stable until

Jan 1, 1965

By D. B. Jugle, J. B. Darby

The equilibrium solubility limits of the transition elements Ti, V, Cr, Fe, and Co in liquid tin were determined in the temperature range from 827" to 1211°K. Since the equilibrium concentration of Ti, V, or Cr in liquid tin is moderately dilute in the temperature range investigated, the solubility data were employed to estimate the partial molar enthalpy and the partial molar excess entropy of solution for the three solutes in liquid tin. The reference state s for titanium or vanadium were selected relative to the solute in an intermetallic compound. The thermodynamic quantities for chromium were calculated relative to pure chromium. RECENT experiments1 have shown that the rate of solution of several transition elements in liquid aluminum can be qualitatively predicted from a knowledge of the temperature dependence of the solvent-rich liquidus. In order to extend the analysis to binary tin systems,&apos; it was necessary to know the equilibrium solubility of several of the first-long-period transition elements in liquid tin. Since solubility data for the tin-rich portion of binary systems are meager, the present investigation was undertaken to determine the equilibrium solubility limit of Ti, V, Cr, Fe, and Co in liquid tin in the temperature range from 850" to 1200°K. EXPERIMENTAL PROCEDURE A useful technique3 to determine the equilibrium solubility of a solute in a liquid-metal solvent consists essentially of placing a pure solute in contact with a pure solvent and allowing sufficient time for equilibrium to be attained at the temperature of interest. Subsequently, the solvent is removed and the equilibrium solute concentration in the solvent is determined by an appropriate analytical procedure. The technique can be applied very successfully to relatively simple systems such as the copper-germanium system.3 However, in many binary systems of transition elements with tin, several intermediate phases are known to exist and precipitation of the phases from solution, in solubility experiments, can lead to an erroneously large solubility. The difficulty was avoided in the present work by equilibration of the most solvent-rich intermediate phase with the pure solvent over a range of temperatures. The compounds employed in this investigation, and the temperature range over which each compound is in equilibrium with liquid tin are listed in Table I. No stable intermediate phases are reported in the chromium-tin system4 and, therefore, pure chromium was utilized as the solute. The stoichiometric compounds were prepared by arc-melting on a water-cooled copper hearth in a helium-argon atmosphere. The elemental tin employed in.this investigation was 99.998 pct pure, and typical lot analyses of the transition elements were reported elsewhere.&apos; A sample of an appropriate solute, in the form of a button and in sufficient quantity to exceed the equilibrium solubility, and the pure tin solvent were placed in a high-purity recrystallized-alumina crucible. The crucible and contents were placed in a horizontal furnace under a high vacuum (10-6 torr) and held at temperature for periods varying between 24 and 72 hr. A water-cooled quench tank, partially filled with diffusion-pump oil, was attached close to one end of the

Jan 1, 1970

By Robert C. Linares

Cubic zinc sulfide has been grown from molten salt solutions substantially below the hexagonal-cubic phase transition of 1020°C. Crystals free of birefringence have been grown from molten lead chloride at temperatures from 500° to 800°C. Factors affecting the optical transmission and the birefringence are discussed. CUBIC zinc sulfide is of interest for electrooptic devices and as an optical coating material. However, it cannot readily be produced as large crystals which are free of birefringence. The birefringence arises from the fact that the cubic ZnS is usually grown as the high-temperature hexagonal phase and is transformed to the lower cubic phase by annealing.&apos; This results in stacking faults, stress, and birefringence. A requirement for the growth of cubic ZnS is that it be grown below the phase transition of 1020°C.2 Crystals of cubic ZnS have been grown below 1020°C by the hydrothermal,3 flux,4 and vapor transport5 techniques. However, these all appear to have limitations in size or quality of material produced. It was felt that a new flux method might have a good chance of overcoming some of the previous problems. Mita6 reported the growth of hexagonal ZnS from molten NaCl and wilke7 reported the growth of iron sulfides from molten lead chloride solution, indicating that molten chlorides make good solvents for sulfides. An investigation of a number of possible molten chlorides as solvents showed that molten PbCl2 has an appreciable solubility for zinc sulfide and that crystals can be grown at temperatures from 500° to 800°C. EXPERIMENTAL Crystal growth was performed in open or sealed Vycor or fused silica tubes, in an argon atmosphere or vacuum. There were no deleterious effects due to using vacuum; however, a sealed essentially isothermal system must be used to prevent vapor transport mechanisms from dominating. This will be discussed later in detail. Noble metal containers were not usable as they were severely attacked by these melts. The materials used were: reagent-grade PbC12, reagent-grade ZnS, optical-coating-grade ZnS, and Irtran 2 (ZnS). Crystal growth was accomplished by both slow cooling techniques and gradient growth techniques. In the slow cooling techniques, 15 g of ZnS and 100 g of PbCl2 were used. The components were placed in the silica tube, heated at 800°C for 2 hr, and then slowly cooled (l° to 10° C per hr) to 500°C. The furnace was constructed so that the tube could be inverted, thus allowing the liquid to drain off the crystals at the end of the run. The gradient runs were made by placing the above mixtures in a silica tube at 550° to 600°c, Fig. 1. A temperature gradient was maintained such that the floating mass of undissolved sulfide was 10° to 50°C warmer than the bottom of the tube. Growth occurred on spontaneously nucleated sites at the cooler bottom. RESULTS When using high cooling rates (5° to 10°C per hr), crystals form in thin sheets perpendicular to the {111} face. Crystals 5 by 5 by 1.2 mm, Fig. 2, have been ob-

Jan 1, 1969