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By G. W. Jones, G. S. Scott

Economic waste caused by mine fires may become considerable,l5 especially if a fire is allowed to spread or temporarily to get beyond control. It is important, therefore, to act promptly whenever a fire is suspected and to make every action count. To contribute toward its extinction effectively it is necessary to know at the earliest possible moment, and continuously thereafter, what is happening at the seat of the fire, which may be in a remote or inaccessible area, and also to recognize what may be expected as a result of any proposed combative measure. In combatting a fire the mining engineer and the chemist should cooperate, first deciding upon the course of action to be taken and then drawing upon the mining engineer's intimate knowledge of the physical structure of the fire area, the cost and time required to carry out proposed operations, and the probable efficiency with which these operations could be performed, and upon the chemist's knowledge for the results to be expected therefrom. After the initial steps to be taken have been decided, it devolves upon the mining engineer to see that they are carried out and upon the chemist to evaluate the results and to keep the mining engineer continuously informed in regard to a variety of matters—such as the composition and toxic or asphyxiating properties of the atmosphere in which the men may be working, whether the fire is increasing or decreasing in intensity and its probable temperature, the quantity of air leakage and the explosion hazards of the fire area. The purpose of this paper is to discuss what the chemist can and cannot contribute as a member of the fire-fighting personnel. The technical literature contains several hundred papers relating directly and indirectly to mine fires, and this fact alone is testimony to the complex nature of the phenomena involved in the birth, life, and final demise of a fire. A fire may be stopped (I) by preventing oxygen from reaching the coal or (2) by removing the conditions necessary for the rapid reaction of coal with oxygen; i.e., decreasing the temperature. All methods of prevention or control necessarily must be based upon one or the other, or both, of these two principles. The chemistry of a fire may be understood readily if the low-temperature oxidation of coal is considered as a starting point; then oxidation at higher temperatures (or combustion); and with these, the composition of the solid and gaseous products resulting from the oxidation or from the effects of the heat liberated. This discussion refers particularly to Pennsylvania anthracite, although much of the material applies equally well to coals of lower rank. Oxidation of Coal Oxidation of coal fundamentally is confined to the surface; that is, the rate at which oxygen penetrates into the interior of a solid block of coal is so slow that it may be ignored."16 Oxidation starts when a fresh surface is exposed, and the rate is

Jan 1, 1942

By G. S. Scott, G. W. Jones

Economic waste caused by mine fires may become considerable,l5 especially if a fire is allowed to spread or temporarily to get beyond control. It is important, therefore, to act promptly whenever a fire is suspected and to make every action count. To contribute toward its extinction effectively it is necessary to know at the earliest possible moment, and continuously thereafter, what is happening at the seat of the fire, which may be in a remote or inaccessible area, and also to recognize what may be expected as a result of any proposed combative measure. In combatting a fire the mining engineer and the chemist should cooperate, first deciding upon the course of action to be taken and then drawing upon the mining engineer's intimate knowledge of the physical structure of the fire area, the cost and time required to carry out proposed operations, and the probable efficiency with which these operations could be performed, and upon the chemist's knowledge for the results to be expected therefrom. After the initial steps to be taken have been decided, it devolves upon the mining engineer to see that they are carried out and upon the chemist to evaluate the results and to keep the mining engineer continuously informed in regard to a variety of matters—such as the composition and toxic or asphyxiating properties of the atmosphere in which the men may be working, whether the fire is increasing or decreasing in intensity and its probable temperature, the quantity of air leakage and the explosion hazards of the fire area. The purpose of this paper is to discuss what the chemist can and cannot contribute as a member of the fire-fighting personnel. The technical literature contains several hundred papers relating directly and indirectly to mine fires, and this fact alone is testimony to the complex nature of the phenomena involved in the birth, life, and final demise of a fire. A fire may be stopped (I) by preventing oxygen from reaching the coal or (2) by removing the conditions necessary for the rapid reaction of coal with oxygen; i.e., decreasing the temperature. All methods of prevention or control necessarily must be based upon one or the other, or both, of these two principles. The chemistry of a fire may be understood readily if the low-temperature oxidation of coal is considered as a starting point; then oxidation at higher temperatures (or combustion); and with these, the composition of the solid and gaseous products resulting from the oxidation or from the effects of the heat liberated. This discussion refers particularly to Pennsylvania anthracite, although much of the material applies equally well to coals of lower rank. Oxidation of Coal Oxidation of coal fundamentally is confined to the surface; that is, the rate at which oxygen penetrates into the interior of a solid block of coal is so slow that it may be ignored."16 Oxidation starts when a fresh surface is exposed, and the rate is

Jan 1, 1942

By H. B. Pulsifer

The unprecedented high price of zinc ore prevailing through the early months of 1915 caused great activity in the Joplin district of Missouri. The Media mill is conspicuous as one of the first of the new "big mills" of the district. The mill was built over a mine previously worked but abandoned in 1912 because of the leanness of the ore and the large quantity of water encountered. The ore prices prevailing—$100 a ton in June, 1915, as against $50 in 1912-—favored the new undertaking. The mill was designed for good recovery so that it might operate in times of depression. In design and equipment, the mill is exclusively local in conception and construction. Former Exploitation The tract of land is a part of the large Guinn holdings; 70 acres are comprised in this particular lot, which is situated just a mile north of the center of Webb City on the Alba line of the Southwest Missouri Electric Railway. The ore lies 242 ft. below the surface at the top of the knoll which is surrounded by the well known properties: Black Cat, Ground Floor, Florence, Hurry-Up, Electrical, and Mercantile. Since the abandonment, in 1913, of the Yellow Dog a bit farther to the north, the Black Cat, Ground Floor, and Florence workings had been flooded. However, as there was no cut through from this side into the area it was proposed to exploit, it was thought that moderate pumping facilities would take care of the water. Three shafts had already been sunk to the ore horizon during the previous operations; the ground was connected by wide drifts and possibly 10 acres mined out, principally about the two southerly shafts which at surface are 8 and 13 ft. lower, respectively, than the collar of the shaft at which the new mill was built. The former mill on the lease was known as the Bohemian Girl. This mill, built in 1910, was removed after some 3 years' work. A head frame and hopper still existed at the middle shaft, sometimes known as the lower Hold Out shaft, but at the most northerly

Jan 1, 1918

By P. Gobin, J. Perez, P. Peguin

The strain-amplitude- dependent part of the internal friction of alluminum after several ther momechanical treatments has been measured in the I-cycle range and at the ambient temperature. The internal friction in the outer layer of the torsional specimen us stress is computed from the experimental data. The curues obtained are analyzed in tevnzs of u coirzbinntion of AH and p, which aye, respectively, due to the vecersible unpinning from weak pills and to the plastic strain. Considerirlg the notion of thermally activated unpinning and repinning, it is shown that in our experimental conditions tlze dislocation lines acl as in the H model of Granato and Liiclze. It is also seen that the internal friction p which appears at higher- strains call be described by a simple expression which is in good agreement with our results. A qualitative interpretatiorz is proposed by combining these new types of intelpnal fviction. We define the internal friction 6 as half the ratio of the dissipated energy aW during one cycle to the maximum supplied strain energy W of a material submitted to a periodic stress. Experiment and theory show that internal friction varies with stress above a critical value.' Below this value the internal friction is strain-amplitude-independent and is often masked by an experimental background; so we shall call it AB. ~bove this critical value, the internal friction is strain-amplitude-dependent. This quantity is usually called aH:' and it can be explained as a thermal unpinning of dislocations.3-6 Furthermore, at higher stresses, a rapid increase of internal friction appears. This phenomenon could be caused by the plastic strain,' so we shall call it Ap. It seems interesting to us to study the influence of several t her momechanical treatments on the curve internal friction 6 vs strain E, in order to study the variation of AH and p with the concentration and the repartition of linear and point defects. In order to try to explain the results obtained, we shall propose and discuss models for H and hp and shall show that we obtain a combination of these two types of internal friction. 1) EXPERIMENTAL PROCEDURE 1) Preparation and Treatment of Specimens. We

Jan 1, 1968

By V. H. Wilhelm

In contrast with the previous year's activity, the California oil industry for 1938 showed a decrease in drilling, market demand, and discovery of new oil reserves, although there was an increase in oil production. Although additions to reserves from new fields and extensions were less than withdrawals during the year, reappraisals of discoveries in 1937 added to new discoreries during 1938 amounted to over 300,000,000 bbl. The following comparative statement shows the important changes in various phases of the industry: Throughout the year the storage situation became progressively more acute, owing principally to less Pacific foreign demand, and increased potential from drilling the newly discovered fields and pools (Fig. 1). California storage increased approximately 32,000,000 bbl. during 1938, most of which (approximately 18,000,000 bbl.) was heavy crude and residuum. The market demand for the year was around 600,000 bbl. per day. Because of the trend toward Diesel power for heavy transportation, the non-gasoline-bearing crudes arc fast becoming a drug on the market. New discoveries were instrumental in increasing the potential production of the state from 1,076,000 bbl. per day in January to an all-time high of 1,420,000 bbl. per day at the close of the year; although the indicated reserves of these new discoveries were not equal to the yearly withdrawal of 249,000,000 bbl. As of the end of 1938, the state was voluntarily curtailed about 58 per cent. As a result of prospecting during the year, six new fields were discovered, three fields were extended, and deeper zones were reached in five of the older fields.

Jan 1, 1939

By V. H. Wilhelm

In contrast with the previous year's activity, the California oil industry for 1938 showed a decrease in drilling, market demand, and discovery of new oil reserves, although there was an increase in oil production. Although additions to reserves from new fields and extensions were less than withdrawals during the year, reappraisals of discoveries in 1937 added to new discoreries during 1938 amounted to over 300,000,000 bbl. The following comparative statement shows the important changes in various phases of the industry: Throughout the year the storage situation became progressively more acute, owing principally to less Pacific foreign demand, and increased potential from drilling the newly discovered fields and pools (Fig. 1). California storage increased approximately 32,000,000 bbl. during 1938, most of which (approximately 18,000,000 bbl.) was heavy crude and residuum. The market demand for the year was around 600,000 bbl. per day. Because of the trend toward Diesel power for heavy transportation, the non-gasoline-bearing crudes arc fast becoming a drug on the market. New discoveries were instrumental in increasing the potential production of the state from 1,076,000 bbl. per day in January to an all-time high of 1,420,000 bbl. per day at the close of the year; although the indicated reserves of these new discoveries were not equal to the yearly withdrawal of 249,000,000 bbl. As of the end of 1938, the state was voluntarily curtailed about 58 per cent. As a result of prospecting during the year, six new fields were discovered, three fields were extended, and deeper zones were reached in five of the older fields.

Jan 1, 1939

By B. M. Larsen, W. E. Shenk

THIS paper describes a method of reversal control of the open-hearth furnace that obtains in practice those effects considered below as essential to a completely automatic control, without appreciable interference with the natural rise and fall in temperature of the regenerative portions of the furnace system. Growing out of some studies of radiation pyrometry in open-hearth regenerators, it was developed during 1934-1938, and has been successfully applied to a number of commercial furnaces. The goal of open-hearth furnace operation is the highest rate of production of steel of proper quality consistent with good refractory life and fuel economy. This requires rapid heat transfer from furnace to charge, which in turn is dependent upon heating the furnace refractories to the highest safe operating temperature. The greater the heat input to the melting chamber, the sooner this limiting temperature will be reached, so that control methods in general that are designed to protect against overheating of refractories should help to maintain maximum fuel input and production rate. For the typical open-hearth system, with fixed regenerator capacity and with rate of fuel input usually restricted in its range of variation, our basic assumption is the idea that the only other important variable that is, the time interval between successive reversals-should also be held constant or within a small range. The present reversal control was designed therefore so that, under normal operating conditions, no arbitrary limitation is imposed other than to keep the reversal interval within the optimum time range. However, since a near approach to completely automatic operation involves protection of refractories through the balancing of furnace end temperatures as well as emergency protection against temperature peaks above some upper limit, it was also felt essential to employ, as an integral part of the control unit, a temperature-measuring instrument to register the true temperature of the refractory surfaces at some critical region in the hot ends of the regenerative zones. As the basic elements of the control, we thus have one "maximum" and one "minimum" time relay and a potentiometer recorder-controller, combined with switches and relays to operate as follows: x. Reversal normally occurs within an optimum range limited by the maximum and minimum settings to about 4 to 6 min. variation, but the actual interval usually is less variable and closer to the minimum setting. 2. The margin between minimum and maximum time is utilized, together with a "floating temperature limit" in the potentiometric control instrument, to correct any

Jan 1, 1945

By E. F. Kingsbury

ONE of the well-known and important uses of the noble or precious metals has been for electrical contacts. In fact, the elements of this group, comprising gold, silver and the six platinum metals, have been called "noble" because of their ability to resist heat and corrosion, properties which were early found to be of importance in good contacts. Of these, platinum and its iridium alloys, palladium, and silver, have been extensively used. In recent years the electrical industry has been responsible for about one-eighth of the total consumption of the platinum metals in the United States. Information is not available as to what part of this one-eighth has been used for contacts but it is certainly an important one. SUBSTITUTES FOR PLATINUM During the past 20 years a considerable number of contact alloys have been proposed in the patent literature largely with the aim of more or less replacing platinum by gold or silver, and some of these alloys are finding increasingly widespread application as the reliability of their performance becomes established. From even the partial data-at hand it appears that this substitution by the less precious metals has replaced at least one-half of the amount of platinum that the entire electrical industry would otherwise be consuming at the present time. While the subject is of considerable interest to the metallurgist it is , even more so to the electrical engineer and it is surprising that the literature records no systematic and comprehensive investigation along these lines. Practically all the scattered work on noble metal contacts has centered around platinum as a Standard and has had two more or less distinct aims. One of these has been the replacement of platinum by cheaper materials, and the other, the development of materials of superior electrical performance. The merit of a contact metal has been assumed to be dependent on its infusibility, and since the more precious metals have the higher melting points there has naturally been an association of the two qualities in the sense that the more precious were

Jan 1, 1928

By H. M. Chance

The recent discoveries of important new gold-districts in limestone, granite, sandstone and porphyry have awakened the more intelligent class of prospectors to a realization of the fact that ally rock may be gold-bearing; that from the appearance of a rock it is impossible to judge whether it carries gold or not; and that gold-ores may occur in any geological formation. As a rule, the professional prospector limits his search to ores and conditions with which he is more or less familiar, and to formations which he regards as favorable to the occurrence of such ores. Hence it often happens that while the very thing he is searching for is in plain sight, he fails to recognize it, and some other individual, possibly less intelligent but more lucky, stumbles blindly upon it. Beginning with the discovery of the California placers by the finding of gold in the tail-race of Sutter's saw-mill—a tale so often told that nearly all have read it in some form—and following the discovery of district after district down to the present time, one is forcibly impressed by the fact that many of the important districts have been discovered by accident; that many such discoveries have been made by unskilled or inexperienced prospectors, and some by persons having no knowledge whatever of prospecting. Thus, the recent Klondike discoveries are said to have been made by a poor salmon-fisherman, who, with his Indian wife, was hunting, not for gold, but for good fishing-grounds; the Comstock lode is said to have been accidentally discovered, and the Ragged Top district in the Black Hills and the Pearce mine in Arizona* are recent notable instances of the same kind.

Jan 1, 1900

By J. A. Elias, R. H. Heyer, J. H. Smith

Plastic anisotropy determined by the ratio of width strain to thickness strain in tensile specimens of low-carbon steels is strongly related to crystallographic preferred orientation. Using(222) Pole figures, a method was developed which permits rapid Predictions of plastic anisotropy for any crystallographic texture or orientation. The method is applied to low-carbon steel sheets in which four different crystallographic orientations were produced by variations in cold rolling and annealing treatments. AnISOTROPIC behavior of metal sheets during plastic deformation has long been evident. A familiar example is earing in cup type draws. During tension testing of sheet specimens, anisotropy results in a difference in width strain as compared with thickness strain. Carpenter and Elam1 observed this phenomenon in single crystals of aluminum for both sheet and rod samples. Lankford, Snyder, and Bauscher2 made tension tests on sheet samples of aluminum-killed low-carbon steel to determine the ratio of the width-to-thickness strains, and showed that this ratio was related to drawing performance. Burns and Heyer3 calculated theoretical ratios of width strain to thickness strain for two specific orientations of the bee system, using <111> as the operative slip direction. These calculated values were in fairly good agreement with the ratios determined by tension tests of low-carbon steel sheets in which these preferred orientations existed. The high degree of plastic anisotropy of silicon steel sheets could also be predicted from their crystallographic structure by these calculations. The present study has been made to show that the anisotropy observed in plastic tensile straining is strongly orientation dependent and can be adequately predicted for many orientations and textures. PLASTIC STRAIN RATIO R In the region of uniform elongation of a tension test specimen the plastic deformation may proceed at different rates in the width and thickness directions. Such anisotropy has been described in the past by the plastic strain ratioR:

Jan 1, 1962

By A. C. Richardson

Troughs or launders are probably the oldest machines used for ore concentration, and their development was suggested no doubt by the natural segregation and stratification of materials that take place in the bed of a stream. Trough washers for coal cleaning were first used in France and Germany about one hundred years ago and have been used in some form or other ever since. The early launders were intermittent or batch machines, and only comparatively recent developments have made them continuous. The chief disadvantage of early launder systems as applied to coal has been that when a satisfactorily clean coal was produced the loss of good coal in the refuse was excessive. Other disadvantages have been the large quantities of water and the great lengths of troughs necessary to treat moderate tonnages of feed. One of the most widely used types of trough washers is the Rheolaveur, which has been developed in the last 25 years. Fig. 1 shows a more or less standard arrangement for fine coal. In this there are four trouglis placed one below the other and sloped a few degrees from the horizontal. Rheo-boxes or draws are provided at intervals in the bottom of the trough for the removal of material deposited from the stream. These draws are spaced substantial distances apart. Some of the rheo-boxes are provided with upward currents of water to modify the horizontal current stratification. In operation it is the function of the first two troughs to remove all refuse material and permit only clean coal to be discharged over the end. In order to accomplish this, large quantities of coal are drawn through the rheo-boxes. The third and fourth troughs are used to recover the coal discharged through the boxes of the first two troughs as a middling product and to discharge a clean refuse. The middlings are returned to the first launder and are usually about equal to 40 per cent of the raw coal being fed to the launder. In considering launder processes, one would reason that the conditions of extreme crowding under which stratification takes place in a flowing stream should effect complete separation in a single pass down a launder.

Jan 1, 1938

By A. C. Richardson

Troughs or launders are probably the oldest machines used for ore concentration, and their development was suggested no doubt by the natural segregation and stratification of materials that take place in the bed of a stream. Trough washers for coal cleaning were first used in France and Germany about one hundred years ago and have been used in some form or other ever since. The early launders were intermittent or batch machines, and only comparatively recent developments have made them continuous. The chief disadvantage of early launder systems as applied to coal has been that when a satisfactorily clean coal was produced the loss of good coal in the refuse was excessive. Other disadvantages have been the large quantities of water and the great lengths of troughs necessary to treat moderate tonnages of feed. One of the most widely used types of trough washers is the Rheolaveur, which has been developed in the last 25 years. Fig. 1 shows a more or less standard arrangement for fine coal. In this there are four trouglis placed one below the other and sloped a few degrees from the horizontal. Rheo-boxes or draws are provided at intervals in the bottom of the trough for the removal of material deposited from the stream. These draws are spaced substantial distances apart. Some of the rheo-boxes are provided with upward currents of water to modify the horizontal current stratification. In operation it is the function of the first two troughs to remove all refuse material and permit only clean coal to be discharged over the end. In order to accomplish this, large quantities of coal are drawn through the rheo-boxes. The third and fourth troughs are used to recover the coal discharged through the boxes of the first two troughs as a middling product and to discharge a clean refuse. The middlings are returned to the first launder and are usually about equal to 40 per cent of the raw coal being fed to the launder. In considering launder processes, one would reason that the conditions of extreme crowding under which stratification takes place in a flowing stream should effect complete separation in a single pass down a launder.

Jan 1, 1938

By C. R. Dale

The need for instruments to measure the movement of fluids and gas in wells has been recognized by engineers for many years. Information regarding flow in the producing interval has a direct bearing on completion practices in new wells and also provides information on the production characteristics of the well. Many hours of engineering time are spent in planning and completing wells but knowledge as to whether or not the original planning has produced the desired results has not always been complete. Many questions such as the following often arise: Why is it that two wells are completed under supposedly identical conditions, yet one well is a good one and the other is a poor one? Are the sands that look the best on the electric log contributing to the production? These and many other conditions in the producing well need to be under- stood in order to develop more efficient production practices and to improve on methods of completing new wells. It is the purpose of this paper to briefly describe one type of instrument, outline the methods of running the equipment and show the results of surveys made under various conditions. With an understanding of the use of this type of survey its importance can be evaluated in relation to the problems encountered by the operator. DESCRIPTION OF INSTRUMENT The instrument is a velocity recorder employing a clock-controlled 16mm film for recording the rpm of an extremely sensitive rotor which is rotated by the flow of fluids or gas in a well. The helical-vaned rotor and shaft, weighing one-half of one ounce are an integral unit exposed to the well fluids and are the only moving parts not enclosed in the fluid-tight housing. No packing or fluid seal of these parts is necessary and the shaft is mounted top and bottom on special jeweled bearings. Fig. A is the lower part of the instrument showing rotor and shaft with the protecting housing sleeve removed. The rpm of the rotor is recorded on the moving film by a combination electrical and optical system. The record is a series of dashes on the film, each dash and space representing twenty (20) revolutions of the rotor. (Film record of survey made in California well showing station recordings at various depths.) As the movement of the film is controlled by the clock the number of dashes and spaces in one minute of film travel represents the rpm of the rotor. The range of the instrument is from 0 to 2,500 rprn. The barrel or housing is 1-11/16 in. OD and seven feet long. Various types of expanding fluid traps are attached to the lower end of the instrument to direct the flow through the 1 in. orifice containing the rotor. The fluid trap for upward flow is shown in Figs. B and C. This assembly consists of eight arms with light spring

Jan 1, 1949

By C. R. Dale

The need for instruments to measure the movement of fluids and gas in wells has been recognized by engineers for many years. Information regarding flow in the producing interval has a direct bearing on completion practices in new wells and also provides information on the production characteristics of the well. Many hours of engineering time are spent in planning and completing wells but knowledge as to whether or not the original planning has produced the desired results has not always been complete. Many questions such as the following often arise: Why is it that two wells are completed under supposedly identical conditions, yet one well is a good one and the other is a poor one? Are the sands that look the best on the electric log contributing to the production? These and many other conditions in the producing well need to be under- stood in order to develop more efficient production practices and to improve on methods of completing new wells. It is the purpose of this paper to briefly describe one type of instrument, outline the methods of running the equipment and show the results of surveys made under various conditions. With an understanding of the use of this type of survey its importance can be evaluated in relation to the problems encountered by the operator. DESCRIPTION OF INSTRUMENT The instrument is a velocity recorder employing a clock-controlled 16mm film for recording the rpm of an extremely sensitive rotor which is rotated by the flow of fluids or gas in a well. The helical-vaned rotor and shaft, weighing one-half of one ounce are an integral unit exposed to the well fluids and are the only moving parts not enclosed in the fluid-tight housing. No packing or fluid seal of these parts is necessary and the shaft is mounted top and bottom on special jeweled bearings. Fig. A is the lower part of the instrument showing rotor and shaft with the protecting housing sleeve removed. The rpm of the rotor is recorded on the moving film by a combination electrical and optical system. The record is a series of dashes on the film, each dash and space representing twenty (20) revolutions of the rotor. (Film record of survey made in California well showing station recordings at various depths.) As the movement of the film is controlled by the clock the number of dashes and spaces in one minute of film travel represents the rpm of the rotor. The range of the instrument is from 0 to 2,500 rprn. The barrel or housing is 1-11/16 in. OD and seven feet long. Various types of expanding fluid traps are attached to the lower end of the instrument to direct the flow through the 1 in. orifice containing the rotor. The fluid trap for upward flow is shown in Figs. B and C. This assembly consists of eight arms with light spring

Jan 1, 1949

E. A. Loria (Product Metallurgical Engineer, Crucible Steel Co. of America, Pittsburgh)—In this interesting paper, our introductory work was quoted. We would like to call attention to our sequel paper on the experimental determination of oxygen in cupola-melted cast iron,20 which was not mentioned. Vacuum-fusion oxygen values (as well as hydrogen and nitrogen) were reported for nine heats of cast iron melted in the Battelle 10-in. cupola under normal operating practice and under oxidizing conditions. The oxygen analyses ranged from 12 to 68 pprn compared to the author&apos;s computed range of 10 to 80 ppm. The average amount of oxygen found in our irons was about 20 pprn and changes in the silicon content of the iron from 1.32 to 2.35 pct had no consistent effect on the oxygen content of the iron. The gas determination specimens were poured in split steel molds that produced a clean pin, 3/8 in. diam and 2 in. long. Because freezing was almost instantaneous, the pins were entirely white iron (nongraphitic). In the early stages of the investigation, the pins were transferred to a mercury-filled trap system immediately after pouring. This was done to collect gas evolved between pouring and analysis. However, it was found that during storage for 4 weeks gas evolution was negligible. Because the vacuum-fusion analysis was usually completed within 4 days of pouring, pins from later heats were not stored in the mercury-trap system. We found some evidence that cast iron picks up oxygen during long storage, because of rusting. Earlier work by the British Cast Iron Research Association has shown that cast irons may be stored for a long time without significant change in their oxygen content. The practical significance of this study (and our own) would be in the improvement of cast-iron quality. Has the author investigated this aspect and reached any conclusions on the effect of oxygen on the mechanical properties of cast iron? The second phase of our study was to determine the properties of the test bars poured simultaneously with the gas analysis specimens. We realize that there may be complicating factors attendant in this procedure.21 Results from many test specimens measuring chill depth, transverse flexure and deflection strength, spiral fluidity, and sensitivity to hardness of gray irons ranging from 12 to 68 pprn oxygen showed that the lowering of transverse strength was the only significant undesirable effect of high oxygen content. A statistical study of the chill test results21 showed that the iron containing 22 to 46 pprn oxygen had forced chill depths that were 2/32 in. below the expected value from their composition, and irons containing less than 16 ppm oxygen had forced chill depths averaging 1/32 in. greater than the expected chill depth. Higher oxygen contents, within the range of 12 to 68 pprn did not increase forced chill depth. With the wedge tests, there was a good linear relationship between carbon equivalent of the irons and their chill depth. The results indicated that oxygen contents below 50 ppm in the iron did not affect chill depth. With 50 to 70 ppm oxygen in the iron, oxygen appeared to have a slight graphitizing tendency. These results are in disagreement with the common belief in gray iron foundries that "oxidized irons" produce high chill depths. It would be appreciated if the author would comment on this subject. Gustaf Ostberg (author&apos;s reply)—In Fig. 1 the legend of line I should read 2 pct C, 1 pct Si. The author wishes to thank Mr. Loria for calling attention to his later work, which was published after the present paper was concluded. The range of oxygen contents quoted seems to agree well with the author&apos;s values. The lack of response to variations in silicon content is probably due to the fact that the oxygen content in most cases was below the saturation level. The absence of temperature dependence, even in the case of saturation, is understandable if the difficulty in formation and escape of the deoxidation products is taken into account.

Jan 1, 1960

By A. Raman

The Nb-Co system was nuestigated in the range 10 to SO at. pct Co with X-rays. A pt phase with the W6Fe.r-type structure occurs in the system between 46 and 52 at, pct Co. Its unit-cell dimensions are nearly identical to those of the p Phases found in the Nb-Fe and Nb-Ni systems. Two Laves phases, one having the MgZnz-type structure and the other the MgCuz-type structure, already t-eported in the literature, are found to exist in the system. The ,l.IgZnz-type phase occurs between 62 and 64 at. pct Co. A MgNi2-type Laves phase, reported in the literature, is no! obtained. A binalry phase is found to exist belozv I000C around 82 at. pct Co. THE cobalt-rich side of the system Nb-Co has been repeatedly investigated by previous inestiators" and the following intermediate phases are known to occur: NbCo, which crystallizes in the MgCu2-type structure and Nbc03,&apos; reported originally by Wall-bam, which has the MgNiz-type structre. Jordan and uwez&apos; as well as lliott&apos; were unable to find the MgNiz-type phase. Two phases, designated as x and y, were reported by Saito and eck.&apos; The phase x was inferred to have a narrow composition range near 77 at. pct Co. No published work is known to the author which reports the investigations in the niobium-rich portions of the system. This paper presents the results of an investigation in the Nb-Co system between 10 and 80 at. pct Co. EXPERIMENTAL PROCEDURE Two or three grams of the alloys under investigation were prepared using niobium (99.9 pct +) and cobalt (98.8 pct + with 0.14 pct Fe and and 0.03 pct C) in a tungsten-electrode arc furnace under commercial argon atmosphere. They were then wrapped in molybdenum sheets and annealed for a period between 5 days and 1 week at 1300°C in high vacuum (10-" orr) or in evacuated quartz amules for 2 weeks at 1000°C. Powders of -325 mesh size were prepared for X-ray work by crushing and grinding the specimens. Subsequent reannealing of the powders was not undertaken since most of the alloys were brittle and broke easily. X-ray powder patterns of the as-cast and annealed samples were prepared in a Siemens cylindrical camera (57.3 mm radius) with Cr-K, radiation. A Siemens diffrac to meter was used to get the X-ray patterns of some new phases. Metal log raphic examination of the alloys supplemented the X-ray findings. RESULTS The results of the X-ray and microstructural analysis Of the alloys are in in Table I. The lattice parameters of the phases are listed in Table 11 for quick reference. A set of micro photographs in Fig. l(n) to (j) show the microstructures of some alloys. A probable equilibrium diagram is drawn in Fig. 2

Jan 1, 1967

By James W. Halley

&apos; FINE-GRAINED " steels have been standard products for many years. This paper describes an investigation of the effects of some of the more common grain-growth; inhibitors used to produce these steels. The properties, response to heat-treatment, and the deoxidation practice necessary to produce "fine-grained" steels have been the subjects of numerous papers. It has been shown that a substantial quantity of&apos; aluminum is necessary to produce this type of steel, and it has been indicated that titanium and zirconium produce a similar result. For some time there was a lively argument between those who felt that aluminum refined the grain and those who felt that aluminum oxide was the effective agent. This argument subsided with an apparent victory for those promoting aluminum oxide. Most of the work on grain size has divided steels into two broad classifications based upon McQuaid and Ehn&apos;s original carburizing test at 1700°F. or some similar test at this temperature. If the steel coarsened at this temperature, it was coarse grained, while if it did not it was fine grained. Quantitative data concerning how much a certain amount of aluminum raised the coarsening temperature and affected the properties, all other factors being constant, are very meager. Similar information regarding titanium and zirconium is practically nonexistent. The published information on aluminum yields some quantitative information. Epstein, Nead and Washburn&apos; gave the first quantitative information on the amount of aluminum necessary to prevent grain growth at 1700°F. They showed that the addition of a pound to a pound and a half of aluminum per ton (0.05 to 0.075 per cent) would assure steel that would not .coarsen during a McQuaid-Ehn test at 1700°F. Herty, McBride and Hough2 reported that a steel containing 0.020 per cent acid-soluble aluminum coarsened between 1742° and 1832°F., while steels containing 0.016 per cent and 0.017 per cent acid-soluble aluminum coarsened between 1652~ and 1742°F. compared with similar aluminum-free steels that started to coarsen at 1580°F. Herty3 also showed a marked improvement in low-temperature notched impact resistance with increasing acid-soluble aluminum up to 0.030 per cent. McQuaid4 compared the coarsening of steels containing 0.011 to 0.204 per cent total aluminum and found a maximum coarsening temperature at 0.098 per cent aluminum. He had no samples between 0.015 and 0.098 per cent aluminum. Houdrement5 found a marked decrease in coarsening temperature with aluminum contents above 0.50 per cent. Kinzel, Crafts and Egan6 found that aluminum and zirconium improved thy low-temperature impact resistance of a low-alloy steel, while titanium was detrimental. Sims7 shows that sulphur increases the coarsening temperature and that the maximum coarsening temperature is between 0.04and 0.06 Per cent added aluminum. The

Jan 1, 1946

By David V. Ragone, James A. Craig, Richard E. Balzhiser

The Gibbs free energies of formation of UC2 and UC were measured by equilibrating two-phase mixtures of UC2 + C and UC, + UC with liquid bismuth. The measured equilibrium concentrations of uranium in the bismuth combined with available activity coefficient information yielded uranium activities in these two-phase regions. Measurements on UC2 were performed over the range 1015 to 1160 K and on UC over the range 1115° to 1165°K. The values obtained for UC2 are in excellent agveement with values determined using combustton calorimetry and low-temperature heat capacity measurements. The UC values are in fair agreement with the calorimetric values, differing by about 10 pct from the calorimetric determination. MUCH interest has been shown in the uranium carbides in recent years because of their potential as nuclear fuels. As nuclear reactor operating temperatures have been raised to increase thermal efficiency, new fuels have been required. The uranium carbides are of interest because of their high melting points, >2000°C, high thermal conductivity, and resistance to irradiation damage. The manufacture and use of uranium carbides are aided by a knowledge of their stability and reactivity under various conditions. In this regard the thermo-chemical properties of the carbides, i.e., heat capacity, heat of formation, free energy of formation, and so forth, are particularly important. A great amount of work has recently been done on the thermodynamics of the U-C system. Unfortunately, however, there has not been good agreement among the various investigations. This study of the free energies of formation of uranium monocarbide and uranium di-carbide in the temperature region 1100°-1200° K was undertaken to help clarify the situation. It should be noted that in the temperature range of this investigation, 1100°- 1200° K, the thermodynam-ically stable phase in equilibrium with graphite is U2C3, not UC2, Fig. 1. However, U2C3 is reported to be stable only under extremely low oxygen and nitrogen pressure. Although UC2 is metastable below 150O°C, it exists under most experimental conditions. It should also be noted that "UC," never exists as UC2 but with compositions near UC1.9. However, "UC2" will be used to designate the dicarbide phase except when the stoi-chiometry is necessary for clarity. METHOD The approach taken in this study of the free energies of formation of UC and UC2 was to determine the thermo- dynamic activities of uranium in the two-phase regions UC, + C and UC + UC, by equilibrating the two-phase mixtures with the liquid bismuth. When a mixture of solid UC2 + C is brought to equilibrium with liquid bismuth, the reaction that occurs is: Neither carbon nor UC, could be detected as dissolved material in the bismuth. The standard free energy for this reaction may be written: In the two-phase region UC, + C, Fig. 1, the thermo-dynamic activities of UC2 and carbon are unity. The activity of uranium in this region was determined by measuring the concentration of uranium in a liquid bismuth melt in equilibrium with the two-phase mixture. This concentration was then used in conjunction with the activity coefficient data of uranium in bismuth reported by Tien et al.&apos; to determine the activity of uranium in the two-phase region, UC, + C. All of the quantities in Eq. [2] were then known, and the AG; (uc,) was evaluated. UC + UC2. For the studies involving UC + UC,, the reaction taking place when the two-phase mixture is brought to equilibrium with liquid bismuth is: The standard free-energy change for this reaction is given by:

Jan 1, 1969

By C. W. Sherman, J. Chipman, H. I. Elvander

J. F. Elliott—This is an excellent piece of work and makes a chemical metallurgist more enthusiastic than ever about what can be done with multicomponent systems, if we have satisfactory data. I have a remark to make on the interpretation of fig. 5. First, I will comment on the problem of activities in solutions. The iron-sulphur system has in its phase diagram an intermediate solid phase FeS. The occurrence of an intermediate phase is normally associated with negative departures from Raoult&apos;s law over a portion of the activity curves in the liquid. (Perhaps it would be better to reserve the phrase "departure from ideality" to departures from Raoult&apos;s law line rather than to departures from Henry&apos;s law line). Fig. 5 indicates that the deviation of the sulphur activity curve from the Henry&apos;s law line is negative;

Jan 1, 1951

By M. J. McPherson

Having worked on the thermodynamics of air/liquid-water mixtures passing through the surface fans of deep mines, I find this paper of great interest and congratulate the authors on producing it. There are two matters, however, deserving discussion. First, the authors have described the classical theory of fog formation with fogging occurring at "supersaturation." In fact, the process of fog formation begins well below 100% humidity. The more strongly hygroscopic nuclei in the atmosphere will attract water molecules and begin to grow at a relative humidity perhaps as low as 70%. The process is a dynamic one with both condensation and evaporation taking place throughout the mixture on microscopic liquid surfaces. As saturation is approached, the rate of condensation accelerates rapidly producing the familiar reduction in visibility. Hygroscopic nuclei are present in all natural atmospheres and under the appropriate conditions of pressure and temperature, will produce clean fogs. However, if the air is polluted by particulates from combustion or other processes then the resultant coagulation with growing liquid particles may produce dense (and sometimes photochemical) smogs. It is this process that is likely to occur in underground mines when moist air is cooled below dew point. Second, the authors have summarized very well the individual measures that might alleviate the problem. In particular, I agree that neither heating nor refrigerating the air, by themselves, provides a satisfactory solution. However, there is a combination of these that provides a neat and effective control of fog formation. This involves a small, self-contained refrigeration unit within a duct but without the usual external heat rejection facility. The air is cooled below dew point and, hence, dehumidified on passing over the cold evaporator coils. The heat from the condenser is rejected back into the air down-stream from the water eliminator, as shown in [Fig. 1]. The duct configuration can be designed to create good mixing at the outlet.

Jan 1, 1984