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By Richard J. Fruehan

ThE thermodynamic activities of nickel and chromium in liquid Ni-Cr alloys have not been previously reported. There have been several investigations on the solid alloys.1-3 In the present investigation the activity of chromium in liquid Ni-Cr alloys at 1600° C was determined by the use of the following galvanic cell, The use of galvanic cells employing solid oxide electrolytes for determining the activity of metals in solid alloys was first demonstrated by Rapp and Maak4 on Cu-Ni alloys between 700° and 1000°C. Recently Schwerdtfeger5 tested the performance of the ZrO2(CaO) electrolyte at 1600°C and found it satisfactory for oxygen pressures as low as 10"12 atm. He also demonstrated the use of solid oxide electrolytes for determining the activities in liquid metal systems in measuring the activity of manganese in Fe-Mn alloys at 1500°C. Extensive investigations have been carried out in this laboratory, exploring the oxygen partial pressure lower limit at which ZrO2(CaO) electrolyte can be used satisfactorily in oxygen galvanic cells at 1600°C. In a paper to be published at a later date,9 it is demonstrated conclusively that ZrO2(CaO) exhibits insignificant electronic conductivity at oxygen pressures down to about 3 x 10"13 atm which is lower than the oxygen partial pressure in equilibrium with Cr-Cr2O3 at 1600°C. Therefore, the activity of chromium can be related to the measured reversible electromotive force of the cell in the present investigation since no electronic short circulating will occur. Fig. 1 is a schematic diagram of the cell used. The Cr-Cr2O3 electrode was made of equal weights of chromium and Cr2O3 powders which were mixed and packed into a recrystallized alumina crucible. A Pt-wire lead was embedded into the Cr-Cr2O3 compact to insure good contact. A ZrO2(CaO) crucible, supplied by the Zirconium Corp. of America, contained the Ni-Cr melt equilibrated with solid Cr2O3. The ZrO2(CaO) crucible was placed on the Cr-Cr2O3 electrode and additional Cr-Cr2O3 mixture was packed around it. Contact with the Ni-Cr alloy was made with a Cr2O3 tube, which is a weak electronic conductor. A platinum wire lead was attached to the Cr2O3 tube. The galvanic cell was lowered slowly into the hot zone of the furnace tube in order to avoid too large a thermal shock which could break the ZrO2 (CaO) crucible. The furnace was con- tinuously flushed with purified argon during the experiment. The temperature was measured with a Pt-Pt/10 pet Rh thermocouple and maintained at 1600° ± 5°C. The electromotive force was measured with a recording potentiometer. The furnace was turned off when measurements were being made in order to avoid induction effects and the reversibility of the cell was demonstrated in the usual manner. The electromotive force was measured several times over a period of approximately 1 hr. During that period the electromotive force remained constant within ± 3 pet and did not continuously drift in any one direction. After the experiment the alloys were analyzed for chromium in the usual manner. The measured electromotive forces of the cell at 1600°C, (2912°F), are listed in Table I. The activity of chromium, with solid pure chromium as the reference state, (a), was calculated using Eq. [l], , n F E I, n lna RT- U] where E is the measured electromotive force, F is the Faraday constant, and n is equal to 3, the number of equivalents per mole, (nF/RT = 18.59 volts'1 at 1600°C). The resulting activities are listed in Table I. The activity of chromium relative to pure liquid chromium was also calculated. The free energy of fusion of chromium at 1600° C was calculated using

Jan 1, 1969

By A. C. Stevenson

THE hoisting equipment selected for use at the Hecla mine in 1907 was one of the first Ilgner type Ward-Leonard controlled hoists put into ser- vice. Development of the Hecla below the 2000-ft. level, which is the ultimate depth of the old equipment, and the additional service required by the "Star," necessitated additional hoisting capacity. It will be our endeavor to give j70u a brief summary of the engineering which determined the selection of the new equipment. The engineer in making his decision as to size, speed, etc., must .make a duty study approximating as closely &s possible the actual opePating conditions which will eventually result. Primarily, it is necessary to know what work must be done. The amount of material which must be hoisted under the maximum condition, as well as its distribution from the various levels of the mine was carefully studied by the mining engineering department, as the ore reserves, their relative-position and the probable method of working them had to be considered. The final figures reached, taking into consideration four different operating conditions, were, in tons per day, as follows:

Jan 1, 1930

By F. Garofalo

It has been shown by various investigators that during constant stress creep the dependence of minimum creep rate, 6,, on stress, o, is given by em = A onat low stress levels, md by 6, = A' exp [ß s] at high stress levels. In these relations A, n, A', and ß are constant at constant temperature. A single relation has been found which satisfies conditions for both high and low stresses and agrees well with experimental results. This relation is 2, = AN (sinh a s)n, where A" is a constant at constunt temperature and a = p/n. This relation also satisfies the linear relation, 6, = k s, found at temperatures near the melting point at low stresses. EXPERIMENTAL creep results have led to a number of empirical relationships between minimum creep rate, 6,, and the applied stress, s. Under conditions of constant stress it is generally found that at low-stress levels,'-' the dependence of minimum creep rate is given by 6, = Asn. At high-stress levels'74 the experimental results fit the relation, 6, = A' exp [po l. In these relations A, n, A' and ß are constant at constant temperature. A model based on climb-of-edge dislocations from a pile-up array leads to a relation similar to that found experimentally at low stresses.' On the other hand. theories based on chemical-reaction rate,5 nonconservatively moving dislocation jogs, and jog migration and climb-of-edge dislocations4 lead to a relation similar to that found experimentally at high stresses. No difference in mechanism between low and high stress levels has been clearly defined; it is questionable whether such a difference really exists. In any event, the major argument usually given in substantiation of a change in mechanism from low to high stresses is that no single relation exists for defining the stress dependence of the creep rate over wide ranges in stress. However, such a relation has been found and is of the form, dm = A" (sinh a s)n, where A" is a constant at con- stant temperature and a = ß/n. This relation agrees well with experimental results over wide ranges in stress and temperature for copper, aluminum, an A1-3.1 pct Mg alloy, and an austenitic stainless steel. STRESS DEPENDENCE OF MINIMUM CREEP RATE At low stress levels the minimum creep rate, gm, depends on the stress, 0, under conditions of constant stress creep through the relation em=Aon [1] The quantities A and n have been defined previously. In the range in which this relation applies, a linear dependence is found in a log em,-log o plot. Above the stress range of application of relation [I], the minimum creep rate increases much mar; rapidly than predicted by relation [I]. This behavior is shown in Fig. 1 for a series of creep tests on copper4 at various temperatures ranging from 673 o to 973°K. Relation [I] is satisfied at the lower stresses, although the results at 973°K are quite limited. In all cases the transition beyond the applicable range of relation [I] is a gradual one indicating no abrupt change in mechanism. For all test temperatures, values of n have been determined from the results in Fig. 1. These are reported in Table I under Alog tm/hlog o. At high stress levels the stress dependence of minimum creep rate under conditions of constant stress is given by im = A' exp [ß a] 2] All factors have been defined previously. In a log em-0 plot, relation [2] predicts a linear function. Experimentally, a pronounced deviation from the prediction of relation [2] is found at lower stresses. As the stress is lowered, the minimum creep rate decreases more rapidly than predicted by relation [2]. This shown for copper in Fig. 2. Again it is found that the transition from high to low stresses is gradual and no really sharp change is found. Values of p determined from the high stress results are given in Table I. The dependence of minimum creep rate on stress at constant temperature for all ranges in stress

Jan 1, 1963

By G. W. Healy, L. F. Sander

was investigated by reacting thin discs of calcium oxide with gas mixtures of CO2, CO, and Son. Its value was 19,300 * 300 cal independent of temperature in this range. No solid solubility of sulfur in calcium oxide was detected within the limits of the experimental method and it is estimated to be below 0.025 pct by weight. The importance of lime in desulfurization is well-established but complete information on the pure phase equilibrium: CaO + 1/2 s2 = CaS + +02 [11 is not yet available. The goal of this work was to evaluate solid solubility of CaS in CaO and to determine the free-energy change associated with Reaction [I] at temperatures of 1400" to 1650°C. The equilibrium constant for Reaction [1] can be written: It is convenient to rewrite Eq. [2] in the form: where A = {Ps /PqJ1'2 has been referred to' as the "sulfurizing power' of a gas mixture. In this work, thin discs of CaO were suspended in a vertical tube furnace and exposed to CO + CO2 + SOz gas mixtures having known values of A. The samples were then analyzed for sulfur. As expected, X-ray diffraction confirmed that CaS was the only sulfur-bearing phase formed at the relatively low oxygen pressures used. EXPERIMENTAL PROCEDURE Reagent-grade CaCO3 was pressed in a 3/8-in.-diam pill die and prefired in air to produce CaO discs weighing between 0.004 and 0.01 g. Several discs were used to provide a suitable weight for chemical analysis while maintaining a large surface area to react with gas mixtures. These were placed in a platinum mesh basket and suspended in the gas stream in the hot zone of a vertical tube furnace. Desired gas mixtures were prepared from cp grade CO and CO2 and anhydrous grade SO2. The method of soap bubble displacement was used to calibrate capillary flow meters. While this gave excellent results with CO and Con, some problems with bubble insta- bility and soap film "drag" arose with the use of SO2 at low flow rates. Hence, frequent sampling and analysis of gas mixtures was carried out to insure proper control of the ingoing SOZ. The furnace used for gas:solid equilibration was a vertical mullite tube externally wound with 60 pct Pt-40 pct Rh wire having a diameter of 0.028 in. An inner tube of $ in. ID served as the reaction chamber having Pyrex ground joints sealed to the mullite to provide gas-tight connections at top and bottom. A Pt-Pt 10 pct Rh thermocouple was inserted into a protection tube adjacent to the sample basket to measure sample temperature during a run. Constant-temperature control to 2C was observed at any desired set point within the range of this investigation. This was accomplished by a control thermocouple imbedded in the furnace windings which served to actuate an electronic controller wired for high-low operation. The sulfur analyses of the solid samples were carried out using a stoichiometric combustion technique based on the method of Fincham and Richardson. Some analyses were done using a modified evolution method3 but these were used primarily to check the results of the combustion method. The results were in good agreement but the combustion technique of-ferred an advantage in economy of time and material. CALCULATION OF GAS EQUILIBRIA Heating a given mixture of CO + CO + SO2 to high temperatures gives rise to a large number of product species. The details of calculating the partial pressures of these products of interaction and dissociation can be found in several references4,5 and need not be repeated here. The thermodynamic data selected for the major species in the gas mixtures are shown in Table I. Equilibrium constants from these reactions were combined with oxygen, carbon, and sulfur balances and a computer program written to facilitate the calculations. Some early difficulties in reproducing experimental results were finally traced to the effect of atmospheric pressure changes. No reference to consideration of this question had been found in the

Jan 1, 1969

By E. A. Steigerwald

E. A. Steigerwald (Thompson Ramo Wooldridge, Inc.1— he authors' results clearly indicate that cracking can be produced by the hydrogen pressure developed during a charging operation. This type of cracking or blistering has also been observed in polycrystalline materials24"28 when the charging conditions are sufficiently severe and is often referred to as irreversible embrittlement since it cannot be removed by a baking treatment. There are additional data, however, which must be considered before a pressure theory can be generally employed to account for all failures which occur as a result of hydrogen. In many cases, hydrogen embrittlement in a tensile test or in delayed failures under static loads is a reversible phenomena which cannot be simply explained on the basis of preexisting cracks generated by the charging operation. It is this aspect of the problem which has prompted many investigators to seek mechanisms other than hydrogen pressure to explain their results.24'n728 Fig. 15 indicates an example where, under specific experimental circumstances, hydrogen embrittlement can occur at liquid nitrogen temperatures. In this case, which has been previously decribed,'' specimens were charged with varying quantities of hydrogen, immediately quenched, and tested in liquid nitrogen (-320°F). A companion set of identical specimens were charged, aged at 300°F to remove the hydrogen, and also tested at -320°F. When the current density was greater than lo-' amp per sq in., embrittlekent occurred in both sets of specimens, indicating that cracking had occurred during charging and the embrittlement, as in the case of Fe-Si single crystals, was irreversible. At current densities between approximately 103 and lo-' amp per sq in, the embrittlement was present only for those specimens which contained hydrogen during the testing sequence. The embrittlement was therefore reversible with respect to the aging and charging operations. Since extensive hydrogen movement would not be expected at -320°F, it is difficult to reconcile these data with a mechanism which requires pressure and pressure dependent growth of preexisting cracks. There are other features of hydrogen embrittlement such as the reversibility of the incubation time for delayed failure with respect to applied stressg0 and the influence of prestraining31 which are also difficult to explain using a pressure model. Any general mechanism of hydrogen embrittlement will have to consider the reversible aspects of the embrittlement data as well as the irreversible portion which has been clearly presented for the Fe-Si crystals and which is consistent with a pressure model. A. S. Tetelman and W. D. Robertson (authors' reply)—he authors agree with Dr. Steigerwald that a general mechanism of hydrogen embrittlement must be applicable in all cases where embrittlement occurs. Dr. Steigerwald's experiments were performed on an iron alloy which has an extremely complex microstructure, and therefore does not lend itself to the direct and detailed observations that can be made in Fe-Si. The change in the characteristics of cracks as a consequence of annealing at 300°F is not really known in detail but it is probable that stress-relaxation (blunting) occurs, dislocations produced near the crack tips will be pinned by carbon atoms, and hydrogen will be lost to the atmosphere. Any, or all of these effects of annealing will alter the ease with which a crack subsequently propagates under applied stress. A quantitative treatment of the problem must take these effects into account. Since diffusional processes are presumably eliminated at -320°F, the general mechanism proposed by Dr. Steigerwald's colleagues cannot be operative at this temperature. A detailed discussion of the general' inapplicability of this mechanism has been presented elsewhere. However, the data presented by Dr. Steigerwald in his discussion can be explained in terms of a pressure model. Crack propagation under internal pressure P and applied stress occurs when where is the total energy expended in creating new surface area and by plastic work at the crack tip. The total crack length increases with increasing current density, since we have shown that it systematically increases with hydrogen concentration and Dr. Steigerwald has shown that hydrogen concentration increases with current density. For large L (high current density) Eq. [I] can be satisfied even if P = 0 and the embrittlement process does not require the presence of hydrogen. Specimens charged at a lower current density will con-

Jan 1, 1963

By Owen F. Jensen

CONSTRUCTION of a ground-water supply includes many operations, which do not end with completion of facilities. Evaluations must be made of the quality of water in various areas and the history of production. Following an analysis of geologic, hydrologic, and chemical data there must be an exploratory drilling program and a study of resulting information. When the well is completed a continuous survey of operating records and basic data is necessary, since designs for future wells are varied as more data becomes available for those already completed. As the following discussion must be limited to a single undertaking, the customary procedure will be outlined for development and construction of a ground-water supply in which more than three wells are involved. Parts of this procedure are applicable for all ground-water supplies. Three possible sites were selected for construction of a paper mill. The problem was that the industry daily required approximately 15 million gallons of water of the best quality available; however, if water of the best quality were not available in the desired amount, water of a poorer quality could be used up to half the required amount, about 7 million gallons. In the preliminary survey approximately 1500 to 2000 square miles were covered for each site. Collected data consisted of several hundred electric logs of oil and gas wells; reports by the U. S. Geological Survey on ground-water resources of localities in and near the area; unpublished records of several hundred water wells including chemical analyses of the water produced and drillers' logs of the wells; records of periodic water-level measurements made in observation wells by the USGS; topographic maps drawn up by USGS and by army engineers; and highway and county road maps. A preliminary report based on study and evaluation of these data was presented to the client, recommending the site with the most favorable and economical ground-water conditions. The study indicated that water of the quality and quantity desired could be developed. In this particular area there were indications that the aquifer could be separated into two zones con- taining water of different chemical character. This chemical character varied somewhat with area, but principally with depth, a factor which later proved an economic advantage in design of the well field. After studying the preliminary report, the client weighed other economic factors as well as ground-water advantages and selected a plant site. Authority was given to proceed with detailed study of the chosen area. Evaluation of preliminary data concerning the area indicated that it should be supplemented with additional information derived from actual exploratory drilling and testing. A flexible plan of exploratory drilling was devised so that data obtained as each test hole was drilled could be correlated with existing data and additional test holes could be located and drilled accordingly. Specific data to be obtained from each test hole were: samples of all formations penetrated; the driller's descriptive log of formations; electric logging surveys; one or more samples of water from selected water-bearing formations; temperature; and water levels and their recovery after periods of production. The area studied in such detail was approximately 400 square miles. Choice of location for the original test holes was based on the preliminary study. The pattern for these test holes was designed to require a minimum number of holes and to allow for interpolation of data between two, three, and four holes. Geologic, hydrologic, and chemical data gathered after completion of the first four test holes showed that the north section was the most desirable in the area, which was then reduced from the original 400 square miles to about 150 square miles for more detailed and intensive study. On the basis of findings from the current test a tentative well field was laid out and a drilling program devised. One test hole was located on the actual plant site and later developed into a small pilot production well equipped with a deep well turbine pump. Water from this well was used for general construction requirements. Another test hole drilled near the pilot production well and adjacent to the proposed route of the well-collection system was used during the pumping test of the pilot production well to determine the degree of interference. From the data thus obtained, calculations were made to determine the coefficients of transmissibility and storage. Three additional holes

Jan 1, 1955

By J. D. Doherty

That America's great coal deposits eventually will be our principal source of liquid as well as solid fuels is generally accepted. Moreover, the day when synthetic oil from coal will begin to supplement our petroleum supplies does not appear to be far off. The American petroleum industry has not spared effort or expenditure in its attempt to keep pace with the demand for oil, and recent production has exceeded expectations. However, the rapidly rising demand for liquid fuels plus the increasing difficulty of finding and developing the new oil needed even to maintain present production rates make it highly unlikely that oil from domestic wells can fully meet future oil requirements. Therefore, it appears that one or more of the following courses must be followed: 1. Curtail oil consumption. 2. Incr ase imports. 3. Develop new sources such as synthetic liquid fuels. All three courses may well be needed, as it is doubtful that any one of the three alternatives alone can satisfactorily solve the problem indicated by the prevailing trend in demand for oil. Curtailment of oil consumption is not a constructive policy, except where oil is being wasted or coal can be readily substituted as in stationary steam plants. Reduced oil supplies for most uses will curb our economic advancement and, in addition to inconveniencing consumers, will have a pronounced adverse effect on American industry. The oil-burner-manufacturing industry already has been dealt a hard blow. Shipments in the first 5 months of 1948 decreased 70 pct from those in the same period in 1947.1 The effect of a similar cut in the automobile industry can be imagined. A severe prolonged shortage of gasoline could seriously disturb our present economic well-being. It might be pointed out also that even the prospect of a shortage or lack of assurance for the future can discourage buyers of equipment, as occurred in the case of oil burners. An increase in our imports of oil seems to be a necessary expedient for the immediate future. Its advantages are that it will require a minimum of manpower and steel in a time of critical shortages and will conserve domestic reserves. Any major dependence upon foreign sources for our oil supplies should be avoided, however. Other nations are increasing their oil consumption more rapidly percentagewise than the United States and eventually will compete with us for the not unlimited world supplies. In peacetime, foreign countries might restrict ship- ments of oil to this country or impose exhorbitant prices. In the event of war, there is serious danger that such sources would be cut off, and American-developed oil fields overseas might even be used against us. Although synthetic fuels cannot relieve any oil shortage that might develop within the next year or two, an immediate start toward a substantial synthetics industry to supplement petroleum not only could help relieve shortages several years hence but also would help establish the much needed "know-how" for large-scale production. By assuring ample future supplies, such a start would permit sound planning by industries dependent upon oil and maintain or restore the confidence of prospective customers for oil-con-suming equipment. If it is agreed that domestic production of crude oil cannot be expected to meet future domestic demands, that oil rationing in general is undesirable. and that too great dependence on foreign oil should be avoided—and the weight of the evidence supports such conclusions—it is inescapable that commercial synthetic fuel production should be developed to supplement domestic petroleum supplies, which, of course, will furnish the bulk of our requirements for yean to come. Sources of Synthetic Oil The three principal sources of synthetic oil are natural gas, oil shale, and coal. A commercial plant using natural gas is under construction, and expansion of this industry is expected.

Jan 1, 1950

By A. V. Bradshaw, R. I. L. Guthrie

The behavior of large bubbles in the size range 4 to 25 cm3, rising through molten silver, has been studied. It was found that rising velocities were equivalent to those in aqueous systems of low viscosity. Mass transfer coefficients for oxygen bubbles dissolving in silver were found to be 0.036 ± 0.007 cm sec-1, being close to those predicted for transfer through the front surface of the spherical cap bubble only. It is suggested that the surface active nature of oxygen in silver could account for the relatively low coefficients obtained. MANY metallurgical processes involve interactions between gas bubbles and liquids. Examples include the removal of carbon monoxide in Open Hearth Steelmak-ing, the removal of sulfur by blowing air through copper matte during converting, and the removal of hydrogen from steel during vacuum degassing or inert gas flushing. The steps involved in such refining processes include; transport of the dissolved species to the bubble interface, adsorption and chemical reaction of the species at the interface, desorption of product molecules from the interface, and transport of product gas into the bulk gas phase of the bubble. It has been concluded1 that all the interfacial steps involved proceed so rapidly at steelmaking temperatures that transport of the solutes, present in the metal, become the important rate controlling factors provided nucleation phenomena are not restrictive. The O-Ag system was chosen for the investigation into gas bubble-molten metal interactions due to the relatively high solubility of oxygen that enables rates of oxygen transfer to be measured from changes in bubble volume. Other advantages of this system include the absence of a stable oxide phase at an oxygen pressure of 1 atm and the relatively low melting point of the metal which permits the use of a metallic container, providing that it is resistant to oxidation. In those metallurgical processes where bubbles have an important influence, bubble volumes are usually greater than 5 cm3. For this reason the present study relates specifically to single large bubbles of oxygen rising in silver. These bubbles adopt the characteristic spherical cap shape similar to that shown in Fig. 1 for a 30 cc bubble rising in water. After an initial investigation to determine the velocities of inert (nitrogen) bubbles rising in molten silver, experiments were carried out with oxygen and the rates of mass transfer between the oxygen bubbles and the silver were measured. EXPERIMENTAL Apparatus. The apparatus, Fig. 2, for containing molten silver, was constructed from "Nimonic 75" Alloy (75 pet Ni, 20 pet Cr, 5 pet Fe, Mn) and provided for the release of single bubbles from an hemispherical cup, situated at the bottom of the column. The cup was turned by translating the rotation of the drive shaft through 90 deg. This was accomplished by the use of a bevelled gear system, and a smooth drive was provided by the lubricating action of the silver on the gears. Since reliable high temperature seals at 1000°C were found to be impracticable, the filling and drive shaft tubes were extended outside the 3.5 kw resistance wire tube furnace, where connections were made using easily accessible O-ring seals. The apparatus remained gas tight to the atmosphere at pressure differentials far in excess of those used. The filling tube was connected via a small bore tube to the differential pressure transducer. Gas could be bubbled into the inverted cup from two i-in. tubes which passed down the inside of the column to preheat the gas. The temperature of the silver was maintained at 1020°C during all experiments. Measurement of Bubble Volume. In order to calculate mass transfer rates, it was necessary to obtain a continuous record of the bubble's volume during its passage through the column of molten silver. The method adopted for measuring the bubble volume involved closing off the top gas space to the atmosphere prior to each experiment, and recording the variation in gage pressure of this space during the formation and rise of the bubble. Since any change in bubble volume results in an equal change in top space volume, Boyles Gas Law may be applied (for isothermal con-

Jan 1, 1970

By J. S. Aronofsky

The first step in a quantitative analysis ot the mechanism of oil displacement by water in a fractured reservoir is usually conceded to be the solution of the differential equation describing the saturation distribution of two immiscible fluids flowing in a porous medium, where the capillary pressure is taken into account. In such a system the production mechanism may consist of displacement of oil both by the flow of water due to natural or artificially imposed pressure gradients and by imbibition, which implies a flow of water not due to external pressure gradients. Owing to the presence of the two oil displacement mechanisms, the mathematical model given by the differential equation intended to describe the system may not properly represent the behavior of the physical system. In fact, in the reservoir the rate of water advance may be very slow, and in the case of a fractured reservoir with a great number of large fractures, the pressure difference determining the flow of water through the matrix may be much less than 1 lb/'psi over lengths of a few feet. In such a case, imbi-bition (the exchange between oil in the matrix and water in the fractures resulting from capillary forces) may become, with time. a significant element of the production mechanism. It occurred Lo the authors, however, that without going into a physical analysis of the process of production, it might be possible by means of simple abstract reasoning to throw some light on the variation of recovery with time under conditions occurring in a highly fractured oil reservoir with rising water table. The object of this paper is to present both the reasoning and its application to a reservoir of the highly fractured type. Specifically, the analysis given here was undertaken to try to explain the increase of recovery (as defined later) with time as observed in this reservoir, without having to assume unlikely variations in the reservoir parameters with depth. This attempt has been successful as will become clear upon comparison of the computed recoveries with the actual field data. ABSTRACT MODEL Let us consider a small volume. of porous matrix saturated with oil at time, t = 0. Let the process of oil displacement by water start at time, t = t,,. At some time, t, the process will have terminated. Then a volume of oil equal to or smaller than the original oil contained in the matrix will have been produced. The first basic assumption that describes the model and guides the forthcoming reasoning is that the oil production from the small volume. dv, is a continuous monotonic function of time and that it converges to a finite limit. Such an assumption is not inconsistent with the results of laboratory waterflood tests as well as with results of imbibition tests where this is, in fact, observed. The second basic assumption is that none of the properties which determine the rate of convergence change sufficiently during the process to affect this rate or the limit. Let it be assumed that the form of the function of time relative to production from the matrix volume. dv, is given by where V,(t) is the volume of oil produced up to that time t. R is the limit toward which the recovery converges, A is a constant giving the rate of convergence, and V,(t) is the volume of oil originally in place in the volume, dv. It should be noted that recovery at time I will be understood here to he It follows that r. tends to R as t tends to infinity. CONSTRUCTION OF RESERVOIR FROM ABSTRACT MODEL Let the reservoir consist of a series of identical blocks of porous matrix stacked vertically and separated by fractures. Let each of these blocks satisfy the conditions of our abstract model. These conditions are: (1) that recovery is a continuous mono-tonic function of time converging to finite limit, and (2) none of the properties that determine the rate of convergence change sufficiently to affect the rate or the limit. Let water be rising in fractures so that oil production from any part of the block starts when the water comes in conLact with it. TOTAL RECOVERY FROM THE RESERVOIR COMPARED TO RECOVERY FROM A SINGLE MODEL ELEMENT As stipulated in Eq. 1, in the case of the abstract model,

By W. B. Price

AT the New York meeting of the American Institute of Mining and Metallurgical Engineers held in February, 1926, W. H. Bassett and J. C. Bradley presented a paper entitled "Exudations on Copper Castings."' The purpose of the present paper, as the title suggests, is to call attention to somewhat similar phenomena which the authors have encountered in brass and bronze. From a study of the examples given, a more-or-less speculative theory of "inverse segregation" is advanced. Protuberances on Admiralty Brass In the rolling mill of the Scovill Manufacturing Co., there have been found quite commonly bars of certain alloys which had a sort of shaggy roughness on the surface due to slight metallic protuberances. No special attention was paid to these until some bars were found on which these protuberances were heavy enough at the bottom of the bars to produce a blistered appearance. A sample of the protuberances was milled off the surface of the bar illustrated (Fig. la) and upon analysis was found to contain 66.66 per cent. copper, 4.02 per cent. tin and 0.03 per cent. lead, whereas the average composition of the bar was 70.21 per cent. copper, 1.21 per cent. tin, and 0.01 per cent. lead. A sample of the shaggy-rough protuberances at the very top of a bar was also analyzed and was found to contain 2.45 per cent. tin, indicating that it was probably of the same origin as the blistered areas. These results were not entirely unexpected for previous analyses of this alloy had revealed that the surface was richer in tin than the rest of the bar. This, of course, is contrary to what we would expect from a consideration of the equilibrium diagram and has been called "inverse segregation." Fig. 16 is a cross-section of a bar through the protuberances on the surface. It reveals that there is a decidedly different structure through the raised areas and seems to indicate that the bar originally solidified

Jan 1, 1927

By HAROLD E. WHITE

LONG before the Stone Age, when man first sought shelter where there-were no natural shelters, such as caves and clefts in the rock, he uprooted trees and planted them upside down so that the roots formed the roof. By selecting trees whose roots grew out in a horizontal direction and; by planting these trees close enough - together, a crude shelter was formed. He then took mud, formed a plaster and covered over the' roots. Later the walls were made by using sticks and twigs and plastering between them. It is natural then, that he wiped his muddy hands on- his own hairy body and soon found that the mud was difficult to remove when, dry. It is due, to this discovery that we mix animal hair in 'our modern plaster to increase its strength. The use of fibrous asbestos in some refractory cements has followed this same principle.

Jan 1, 1929

John Birkinbine, Philadelphia, Pa.: We have in the Institute two Dudleys—Dr. Charles B. Dudley, who has so thoroughly studied the chemical composition and physical behavior of rail-steel, and Dr. P. H. Dudley, whose investigations and

Jan 1, 1900

By Wm. R. Dotson

Forty years ago the atom was split and the Age of Fission dawned. Uranium was the element used in this earth-shaking accomplishment. Thitherto almost unknown to the man in the street, uranium soon became widely and persistently sought. And the quest for this unique material is not likely to diminish during this century. To find is one thing; to own is another. Who owns uranium in the ground? Where no mineral rights in the land have been severed by devise, grant, reservation or lease, the uranium belongs to the fee simple owner of the land. But where there has been a conveyance or reservation of all or part of the "minerals", determining WHAT a substance is has been the traditional way of determining WHO owns it. What, then, is this element called uranium? The 1907 edition of Watts Dictionary of Chemistry calls it "a lustrous, hard, silver-white metal". Of nature's three prime divisions it falls within the embrace of the mineral kingdom - substances neither animal nor vegetable. In its natural state uranium always is combined with other elements or substances in the form of an ore mineral. May we, then, put to rest any doubt or question as to the nature of uranium and classify it for all purposes, including that of ownership, as mineral? Not quite! That self-same logic would find oil and gas primly ensconced in the animal or vegetable kingdom. Technically, oil and gas are not minerals but legally they have been classified as such. Why? The Supreme Court of Tennessee sought the answer in 1897 in the case of Murray v. Allard, 43 S.W. 355. After citing authorities pro and con, and while admitting their origin to be "decomposition of marine or vegetable organises" that court firmly concluded that since they were obtained by a form of mining, oil and gas were minerals. From the above example two elementary truths emerge. First, for purposes of ownership, uranium is and will be whatever the courts say it is. Secondly, the courts historically and currently favor a practical rather than technical test to determine the "mineral" character of a substance. So now we turn to the jurisprudence for enlightenment and definition. EARLY CASES ALLOT URANIUM TO MINERAL OWNERS Two early cases involving the ownership of uranium followed what had been well-settled mineral within the meaning of the conveyances involved, confirming ownership in the mineral owners. In 1956 the U. S. District Court for New Mexico in the case of New Mexico and Arizona Land Company v. Elkins, 137 F. Supp. 767, appeal dism'd 239 F.2d 645 (10th Cir. 1956), found that a 1946 deed reservation of "all oil, gas and minerals underlying or appurtenant to said lands" included uranium and thorium. The court reasoned that uranium and thorium, being minerals within the scientific, geological and practical meaning of the term, would certainly constitute minerals within the purview of the reservation. While agreeing that uranium and thorium were "minerals", defendants argued that at the tine of execution of the conveyance it could not have been the intention of the parties to reserve them because they had no commercial value in the locality and were, in fact, not known to there exist until their later discovery in 1950. The court re¬jected, as a matter of law, this "lack of knowledge" theory citing the Supreme Court of Kentucky holding in Maynard v. McHenry, 113 S.W. 2d 13, that: "The mere fact that a particular mineral has not been discovered in the vicinity of the land conveyed or is unknown at the time the deed is executed rules of construction and held that uranium was a does not alter the rule . . ." that a grant or exception of "mineral" in a deed includes all mineral substances which can be taken from the land unless restrictive language is used indicating that the parties contemplated something less general than all substances legally cognizable as minerals. Further, argued the defendants, the only feasible mining procedure for such substances was open pit or strip mining, which would destroy the value of the land for grazing or agriculture. Finding that the language of the reservation was clear and unambiguous, the court would not permit the admission of extrinsic evidence as to mining procedures required. Elkins is the first uranium case construing the granting clause involved. In 1958 the Texas Court of Civil Appeals at San Antonio, in Cain v. Neuman, 316 S.W. 2d 915, no writ, held that a 1918 lease conveying "all of the oil, gas, coal and other minerals in and under" the land involved covered uranium. The lease provided a royalty of 1/10th on "other minerals." "We find no Texas precedent which discusses uranium," said the court, "but the usual arguments that uranium is not embraced within a lease are that the ejusden generis rule excludes uranium from the meaning of the lease

Jan 1, 1979

By E. Lifshin, R. E. Hanneman

QUANTITATIVE applications of the electron micro-beam probe frequently involve the evaluation of complex mathematical expressions and/or the analysis of large amounts of experimental data. The purpose of this communication is to describe briefly a versatile and useful computer program system that is applicable to analyze rapidly a wide variety of practical microprobe problems. This system consists of a group of ten FORTRAN programs that can be stored on tape, cards, or in the memory disc of the computer. These programs, or links, can be run individually or in any prespecified sequence without interrupting the operation of the computer or without destroying information which is being transfered from one link to another. For the program system described here a GE-235 computer with disc storage was used, so that the DCHAIN method of program linking was employed. Included in the library are programs to: 1) initiate analysis of a new set of data and transfer control between all other programs in any predetermined manner; 2) generate theoretical calibration curves of composition vs relative intensity; 3) generate empirical deviation parameters from least-square fits of experimental calibration data from standards of known composition; 4) convert raw X-ray data to corrected composition; 5) determine inter diffusion coefficients by Matano analysis of con centrat ion -distance data on a uniaxial diffusion couple; 6) determine activation energies and frequency factors of temperature-activated processes such as diffusion; and 7) generate calibration curves for determination of the thickness of thin films using microanalysis. A detailed description of these computer programs and their underlying principles is available on request from the authors."' The first program to generate theoretical calibration curves of corrected relative intensities vs composition uses the Poole and Thomas atomic number correction' and the Philibert absorption factor' with a voltage-dependent mass absorption coefficient for electrons in the alloy. A modified Castaing fluores- cence correction is also used which includes the effects of both Ka and KO radiation and over voltage.' Once the theoretical curves have been calculated in 1 wt pct intervals, these results are least-squares fit to obtain Ziebold deviation parameters' which are stored in COMMON in the computer memory. The net discrepancies between the original theoretical calibration curve and the regenerated curve using the Ziebold parameter are computed. Although this link is explicitly written for K-K fluorescent interactions, it can be applied to K-L, L-K, and L-L interactions as previously disc~ssed."~ Similar programs have also been written to utilize the Wittry fluorescence correction, Birks combined corrections, and various other corrections.' These modified programs have proved to be quite useful for quantitative comparisons of the results of the various theories. The program for conversion of raw X-ray data to corrected composition includes corrections for drift, backround, and instrumental dead time. The corrected intensities are converted to composition by use of the Ziebold equation"2 and parameter obtained from the program system. The results can be obtained for either atom or weight fractions. In addition to accurately computing interdiffusion coefficients the Matano analysis program calculates least-square smoothed values of concentration, concentration gradient, and curvature for each point on the raw input concentration profile. In order to obtain high accuracies a unique method of performing a least-square polynomial fit to incrementally advancing profile segments which overlap is used.' This program has been successfully modified for use in ternary diffusion problems3 and can readily be modified to handle analysis of diffusion profiles which include phase boundary discontinuities. This link is generally applicable to analysis of interdiffusion data obtained by other techniques as well as by the microprobe. The primary function of the next program is to least-squares fit experimental diffusion data to the normal Arrhenius function: D = Doexp(-Q/RT), to obtain values of Do and Q. In addition the probable error and one, two, and three u statistical confidence limits of DO, Q, and log D are evaluated. This program is also directly useful for analysis of any other simple temperature-activated processes including conductivity, and certain deformation and chemical processes. The program to generate calibration curves for film-thickness determination using the microprobe is based on a numerical integration of the equation derived by Cockett and ~avis.' Values of film thickness obtained by this program for copper on various substrates are in good agreement with measurements made by other techniques. Versions of the above program system have been prepared for use with or without a remote teletype connection to the computer for processing on either a real-time or time-share basis. The instrumentation coupling a microprobe to a teletype for automatic data collection and analysis by the presently described program system has been reported elsewhere by the authors.' If teletype equipment is not used to communicate with the computer, standard methods of card reading and tape reading can be used. In either

Jan 1, 1967

By R. L. Dietrich

Magnesium alloy sheet has less ability to accept bending at room temperature than most of the heavier metals. In work designed to improve the bend properties, the preferred orientation of the sheet is of major importance as it is in all studies of the properties of wrought magnesium products. When rolled into sheet, all of the common magnesium alloys form an orientation texture having the basal (002) planes approaching parallel to the surface of the sheet. This texture is only slightly affected by annealing. Magnesium single crystals are highly anisotropic, and, as might be expected, so are magnesium alloy wrought products in which a strong preferred orientation is developed. It is therefore not surprising that bend properties are affected by orientation. Ansel and Betterton1 reported that the orientation of AZ3lXt sheet varies from surface to center and that bend properties are improved by etching away the sharply oriented material at the surface of the sheet to reach the more broadly oriented structure below. This paper covers a study of that orientation, either during the rolling process or by treatment of the finished sheet, in an effort to improve the bend properties and toughness of sheet. Literature The orientation texture of magnesium and magnesium alloy sheet has been studied extensively. Early determinations2 showed that pure magnesium sheet has a preferred orientation in which the basal planes are parallel to the sheet surface within very narrow limits. J. C. hIcDonald3 and J. D. Hanawalt4 reported that sheet containing a small amount of calcium develops a "double" texture, that is, the majority of the basal planes are a few degrees from parallel to the surface and there is a noticeable vacancy at the parallel position. Bakarian5 made careful quantitative pole figures of both pure magnesium sheet and MI alloy SEPTEMBER 1949 sheet which show these features. In all of these studies, however, the orientation was determined by transmission methods in which the resulting pattern is an average through the thickness of the sheet. The tendency of wrought metal to exhibit a different orientation at the surface from that in the center has been reported by many investigators. G. von Vargha and G. Wasserman6 found that with copper, aluminum, iron, and brass the textures of rolled compared to drawn wires were the same at the center but differed markedly at the surface. It was also reported by investigators7 that the orientation of rolled aluminum varies from surface to center. Har-greaves8 found that the surface texture of AM503 (magnesium alloy similar to MI) sheet was different from the center texture. It is reported by Edmunds and Fuller9 that zinc alloy sheet sometimes had a thin layer at the surface with a strong orientation of the basal planes parallel to the surface, which, if present, impaired the bend properties of the sheet. Part1 Surface Orientation ofMag- nesium Alloy Sheet and the Effect on Properties Attempts to correlate the bend properties of magnesium alloy sheet with tension ductility over short gauge lengths proved unsuccessful and the subsequent investigation showed that nonuniformity in orientation is a con- tributing factor as the properties of the surface material have a much more important effect in bending than in tension. A program to study the relationship between surface orientation at the surface and bend properties was then undertaken. First, the effect of etching away the surface of sheet on the bend properties and the orientations at the various depths were studied. Sheet samples of M1, AZ31X, and AZ61X were etched in dilute nitric acid to remove the surface material for various depths to 0.015 in. As may be seen in Table 1, the minimum bend radius improved considerably as the surface layers were etched away but it was necessary to etch the sheet quite deeply, much more so than was found necessary by Edmunds and Fuller9 on zinc sheet. It is also apparent that the amount of etching required is a function of the sheet thickness. In all of this work, radii were measured as R/t, the radius divided by the sheet thickness, in order to eliminate the effect of the reduction in sheet thickness produced by the etching. To determine the orientation texture of the sheet, X ray reflection patterns were taken using copper radiation with the bearn striking the specimen at an angle of 17' to the surface, which is the Bragg angle for the (002) planes of magnesium. Two exposures were made of each specimen, one with the beam perpendicular to the rolling direction and the other with the beam parallel to the rolling direction. The symmetry of the preferred orientation in magnesium sheet is such that these two photographs gave an approximation of the pole figure sufficiently accurate for qualitative work and it was not thought worthwhile to make complete pole figures. These X ray patterns show that the orientation has a much narrower spread at the original surface of the sheet than below the surface. The narrow spread is found in sheet having the majority of the basal planes (002) parallel to the surface, and since this is an unfavorable position for slip, it is

Jan 1, 1950

By John Fritz

TROUGH it is not a condition of the Award, the fact is that the John Fritz Medal never has been given to an engineer who had not already received one or more similar awards. This "medal for medalists," on the evening of April 20, was presented to Daniel C. Jackling at a special dinner held at the Union League Club in New York. The citation read "For notable industrial achievement in initiating mass production of copper from low-grade ores through the application of engineering principles." The present award recognizes the same accomplishment-the launching and guiding to the port of marvelous success of the Utah Copper Co., first of the so-called "Porphyries"-as did the award of the William Lawrence Saunders Gold Medal by the A.I.M.E. in 1930, and before that the Award of the Gold Medal of the Mining and Metallurgical Society of America in 1926. Following the custom a biography of the Medalist had been published in a small pamphlet as a supplement to the John Fritz Medal Book. T. A. Rickard was the au¬thor of the sketch of Mr. Jackling, an innovation being the placing of a copy of the booklet at the place of each of the diners. The committee in charge of the dinner consisted of two past-presidents: R. E. Tally, of the A.I.M.E., who was chairman; Bancroft Gherardi, of the A.I.E.E.; and Thaddeus Merriman, director of the A. S. C. E., the John Fritz Medal being a joint award of the four societies. Frederick M. Becket, President of the A.I.M.E., as chairman for the occasion, briefly stated the purpose of the dinner. He stressed his satisfaction that the award was symbolic of the cooperative professional activities of the four great national organizations of engineers. He introduced Francis Lee Stuart, past-president of the A.S.C.E. and now chairman of the John Fritz Medal Board of Award. Mr. Stuart outlined the history and purpose of the Medal established in 1902 in memory of John Fritz, of Bethlehem, Pa., one of the great pioneers of America's iron and steel industry, metallurgist, and president of the A.I.M.E. in 1894. Mr. Stuart called the roll of former John Fritz Medalists, three of whom, Ralph Modjeski, J. Waldo Smith, and Ambrose Swasey, were present to do honor to Mr. Jackling. He then introduced George Otis Smith, whose privilege it was to present the Medalist for 1933. Dr. Smith was the senior of the four A.I.M.E. representatives on the Board that last year selected Mr. Jackling for the honor. His speech follows in full.

Jan 1, 1933

By N. A. Zeigler

GRaphitization phenomena occurring in solid cast iron have principally been studied from the angle of the reactions taking place during annealing of white castings in the manufacturing of malleable iron. The selected bibliography at the end of this paper presents the high spots of the published information in this field. Graph-itization of gray iron upon reheating has received much less attention, primarily because only on rare occasions is this material subjected to any kind of industrial heat-treating. Moreovcr, articles made from gray iron are seldom used commercially at temperatures when any graphitization can take place. When used in such conditions, it is assumed that the articles can be replaced at frequent intervals, which can be afforded because of the low cost of gray iron. However, there is at least one commercial process in which articles made from gray iron, during their manufacturing processing, are subjectcd to rather high temperatures; that is, manufacturing of cast-iron enamelware, which is glazed at about 1600° to 1700°F. (870' to 930°C.) From practical experience, it has been found that one of the convenient and economical compositions of gray iron suitable for enameling is, in round figures, as follows: Si, 2.50 per cent; Mn, 0.35; S, 0.07; P, 0.80; T.C., 3.35; C.C., 0.70. Since this iron usually is cast into thin-walled sections, the percentage of com- bined carbon in it is relatively high. Upon heating in the enameling furnaces, this combined carbon graphitizes, which causes permanent dimensional changes of the articles. Obviously, from practical considerations, it is desirable to maintain these dimensional changes as constant as possible. In the course of experimentation with this iron, two series of experimental heats were prepared in which the manganese to sulphur ratio of the standard cupola metal was offset by ladle additions of: (I) progressively larger amounts of sulphur, and (2) progressively larger amounts of manganese. Each one of these ladle charges was cast into experimental plates 8 by 4 in. and about 5/16 in. thick. All told, 13 ladle charges were thus treated. All of them are listed in Table I, together with their chemical analyses. It may be noted that the manganese to sulphur ratio in these samples ranges between 1.2 and 30.2. Every one of these compositions was subjected to thermal allalysis, using an automatic, self-recording differential dila-tometer. The specimens used in this instrument are 50 mm. long and 4 mm. in diameter. During the dilatometer cycle they are kept under a vacuum of about 3 microns. Each one of them was subjected to a thermal cycle by heating it to I830°F. (1000°C.) in 3 hr. and cooling to room temperaturc in 5 hr. Figs. I, 2 and 3 present three automatically recorded dilatometer curves for irons: Serial No. I (normal composition), Serial No. 6 (high sulphur), and Serial No. 13 (high manganese). All three of these figures are

Jan 1, 1945

By E. Breinan, M. Salkind

Al3Ni whiskers were chemically extracted from unidirectionally solidified Al-A13Ni eutectic ingots, bent into loops, and heated for 0.1 to 10 hr at 320°, 415", and 510°C. The initial strains ranged from 0.003 to 0.055. In all cases, permanent plastic deformation was noted after heat treatment. The deformation consisted of relatively uniform bending at low stresses and temperatures and short times and kinking followed by fracture at high stresses and temperatures and long times. After kinking, the whisker segments adjacent to the kinks were found to have straightened, which is evidence of a dislocation condensation mechanism. The range of temperatures and strains at which time dependent plastic deformation was found indicates that creep of whiskers probably plays a role in the creep of A13Ni whisker-reinforced aluminum. WHISKERS may be defined as nearly perfect single crystals which exhibit high strength. Because they can support high stresses at relatively low strains, they have been successfully employed in reinforcing metals at both ambient and elevated temperatures. In studying the creep behavior of A13Ni whisker-reinforced aluminum at elevated temperatures,1,2 it was noted that the composites exhibited measurable creep deformation. This investigation of the creep relaxation of individual A13Ni whiskel, extracted chemically from the composite was initiated to determine if creep of whiskers could con. "bute to the overall creep of the composite material. Many observations of plastic deformation of metal and halide whiskers have been made. Brenner3-8 noted that copper, silver, and iron whiskers exhibited heterogeneous plastic deformation at room temperature when strained beyond their yield points. Gyulai9 and Gordon10 observed plastic deformation of relatively large (>3 µ) NaCl and KC1 whiskers, although the smallest, most perfect whiskers were completely elastic. Eisner" noted plastic deformation and microcreep of iron and silicon whiskers at room temperature after straining beyond the yield point. Whiskers reported to exhibit creep at stresses below the yield point were zinc1'-" and Silicon.15 Cabrera and price" observed some zinc whiskers which crept at room temperature after a short incubation period but then stopped creeping after a short time. Because some of their specimens exhibited no creep, they concluded that those whiskers that crept were relatively imperfect. Pearson, Reed, and Feldman15 observed similar creep behavior of silicon whiskers at 800°C. They also concluded that creep of the whiskers was a result of imperfections in their crystals. Brenner16 observed delayed failure of A12O3 whiskers at elevated temperatures but found no evidence of plastic deformation up to 2030°C (99 pct of E.EREINAN and M.SALKIND,JuniorMembers AIME,are Research Scientist and Chief, respectively, Advanced Metallurgy Section, United Aircraft Research Laboratories, East Hartford, Conn. Maunscript submitted April 5, 1968. IMD the melting temperature). Brenner also noted7 that some copper and iron whiskers exhibited delayed kinking above 350°C while others did not. One can conclude from these observations that small relatively perfect whiskers could exhibit completely elastic behavior during sustained elevated-temperature loading of composites. Since A13Ni whiskers tested in both bending and tension were found to exhibit no evidence of plastic deformation at room temperature'7'18 this study was initiated to determine whether or not creep of A13Ni whiskers occurred at the elevated temperatures at which creep in the composites was observed. Whiskers were chemically extracted from ingots of unidirectionally solidified A1-A13Ni eutectic, constrained in bending to various elastic strains and heat-treated. The bending constraints were removed after heat treatment and the amount of permanent set was taken as a measure of the time-dependent plastic deformation. EXPERIMENTAL PROCEDURES Ingots of eutectic Al-A13Ni containing nominally 6.2 wt pet Ni were unidirectionally solidified at approximately 11 cm per hr using a process described elsewhere.19,20 The starting materials were 99.99 pct pure. Cylindrical sections cut from the center of each ingot were placed in a 3 pct aqueous solution of hydrochloric acid and the whiskers were extracted as described previously.17 The whiskers nearest the surface were blackened somewhat due to overexposure to the acid while the center of the ingot was being dissolved These partially attacked whiskers were discarded. An intermediate zone of silver-gray-colored whiskers was collected and stored in methanol for use in relaxation experiments. Individual long pieces of A13Ni whiskers were placed on Fisher Precleaned Microscope Slides. These normally straight whiskers were bent elastically into arcs or loops of varying radii by manipulating their ends with a slender probe. The mass attraction between the whisker and the probe was sufficient to cause the whisker to follow the probe. The whiskers were retained in the elastic bend by the surface tension of a fine residual film on the slides. By using long whiskers, the action of the surface tension on the unlooped ends of the whisker allowed high elastic strains to be maintained in the loops. After each whisker was bent, a photomicrograph was taken for use in measuring the bending strain. The range of strains studied was 0.003 to 0.055. The bent whiskers were then encapsulated in Pyrex tubes at pressures between 10"6 and 5 x 10"6 mm of mercury and heat-treated at 320°, 415°, and 510°C (respectively 53, 61, and 70 pct of the peritectic decomposition temperature). After each heat treatment, the liquid film on the slides was found to have dried, but the whiskers were held in their original shapes by a residue on the slide. The minimum radius of curvature of each bent whisker was measured before and

Jan 1, 1969

By E. F. Evoy

The uranium deposit of Gunnar Mines Ltd. is on south shore of Crackingstone Peninsula in the Beaverlodge area of northern Saskatchewan. The property spans St. Mary's Channel, a narrow waterway separating the mainland from a group of islands in Lake Athabasca. The mine property, consisting of 12 claims and 7 fractions, was staked in July 1952 by A. O. Zeemel and W. J. Blair. Diamond drilling commenced in the fall of that year and continued until the spring of 1954. In that interval, some 70,000 ft of drilling outlined an orebody plunging from the surface south-ward to a depth of 1000 ft below the shore of St. Mary's Channel. The last 9000 ft of drilling was through lake ice, and when this was interrupted by spring breakup, sufficient ore reserves had been established to warrant the present operation. Surface drilling was therefore terminated.

May 1, 1956

By Martha Teach Gnudi, Cyril Stanley Smith

Jan 1, 1942