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By Bernard E. Fernow

About eight years ago a comprehensive study of American timbers was begun in the U. S. Division of Forestry with a twofold object. On the one hand, it was desired to deternliiie the working-qualities of our numerous economically important timbers, and to furnish reliable standards of strength. 011 the other hand, it was intended to get a clearer insight into the properties and behavior of wood in general, with a view of establishing more rational methods in its use, and to furnish data for physical inspectioil which would permit an intelligent application of the standards of strength, and place upon a rational foundation the so-called " factor of safety," which is at present a mere baseless guess. The first object, namely, the establishment of standards for any given species, requires a very large series of tests, since Wood is an exceedingly variable substance, so much so that in the same tree a variation of 50 per cent. in strength may be found; hence the greater need of rational data of inspection. So far, the insufficient appropriations and facilities at our disposal have permitted us to establish really reliable standards for five species of southern conifers only. These have been deduced from nearly 20,000 tests. Besides these, 10,000 other tests have furnished indicatious regarding some two dozen other species. This work is now entirely abandoned, waiting for more prosperous times. The study of wood in general, however, can be carried on with smaller means, and has this year yielded not only very interesting, but highly important results, which will soon be published in detail. It is the purpose of this paper to make to the Institute the

Jan 1, 1899

By Robert W. Hunt

THE first pump of this character, made by H. R. Worthington, and, so far as the writer is informed, the first and only one of this kind ever constructed, is now in daily use in the above-named works. The water-pressure necessary for the working of the hydraulic machinery of this plant had been supplied, up to the time of the building of this pump, by two Worthington Duplex High Pressure Pumps, having steam-cylinders of 20 inches diameter and 12-inch stroke, with water-plungers of 72 inches diameter; eight inlet and eight outlet valves of 22 inches diameter, and pumping into a 6-inch pipe. These pumps required a large amount of steam, and, in consequence of the various additions to their duty, their capacity became far short of the work required. In preference to putting in another engine of the same class, it was decided to accept Mr. Worthington's proposition to build the compound one under description, he guaranteeing that it should be equal to the demands of the works, and at the same time cause a saving of from 5 to 6 tons of coal per day from the amount required to run the two old pumps. The new engine has been in operation about one month, and so far has exceeded the most sanguine expectations. It consists of two high-pressure cylinders of 21 inches and two low-pressure ones of 36g inches diameter, by 36-inch stroke, with water-plungers of 91 inches diameter. There are two air-pumps of 20 inches diameter by 18-inch stroke; the condenser being 24 inches diameter by 60 inches high. Both cylinders are jacketed with wood and felt, and the low-pressure cylinder also with live steam. The high and low pressure steam-cylinders are in line and immediately adjoining each other, while the inconveniences attending an internal stuffing-box are avoided by having two piston-rods for each of the low-pressure cylinders, running through stuffing-boxes on the outside of the smaller high-pressure ones. The steam-valves are very ingeniously designed balanced

Jan 1, 1876

By Joseph Hyde Pratt, Douglas B. Sterrett

Monazite is one of the minerals which, for a long time, was considered somewhat rare in its occurrence, but, upon a commercial demand arising for it, prospectors and engineers soon located large deposits of it in the Carolinas arid Brazil, and the supply has always been able to meet the demand. During 1908 further sources of supply of monazite have been discovered and developed in Idaho. North and South Carolina, however, are the only States that have thus far put any monazite on the market. Monazite is essentially an anhydrous phosphate of the rare-earth metals,ceriunl, lanthanum, and didymium,(Ce,La,Di)PO,. There is nearly always present a varying but small percentage of thoria, Tho2, and silicic acid, SiO2,, which are very probably united in the form of a thorium silicate, ThSiO4. Some mona-zites contain but a fraction of a per cent. of thoria, while others have been recorded that showed the presence of from 18 to 32 per cent.; but the majority contain from 3 to 9 per cent. of this oxide. It is the presence of the thorium oxide that gives the monazite its commercial value. The analysis occasionally shows also the presence of other constituents, as the yttrium and erbium oxides, zirconia, alumina, magnesia, lime, iron oxides, manganese oxide, and titanium oxide. Monazite is light-yellow, honey-yellow, reddish-, brownish-, or greenish-yellop. in color, with a resinous to vitreous luster, and is translucent to subtransparent. It is brittle, with a con-choidal to uneven fracture, and is from 5 to 5.5 in hardness, and from 4.64 to 5.3 in specific gravity. It crystallizes in the monoclinic system, and some crystals have been observed that werc 6 in. in length. The more perfect crystals are,-however,

Jan 1, 1910

By K. L. Meissner

IT is well known that the so-called pure aluminum contains noticeable amounts of impurities, chiefly iron and silicon, and many investigators have studied the forms in which these impurities exist. Hanson and Archbutt1 state that iron exists in aluminum as FeAl3 and silicon as elementary Si. The solubility of FeAl3 in solid aluminum is practically zero, or at, least so small that the smallest trace of this compound is always visible as a separate constituent. Under the microscope an untrained eye can hardly distinguish, without etching, the two constituents FeAl3 and Si, but they can be differentiated by suitable etching reagents. Anderson2 also found the same results. At the same time, Merica, Waltenberg, and Freeman3 found a constituent of unknown composition. They found a small thermal effect, at 610° C., on the cooling curves of aluminum with small amounts of iron and silicon. The intensity of this effect increased with increasing silicon content, until an effect occured at 576° C. due to the eutectic between aluminum and silicon. The authors ascribed the effect at 610° C. to a compound, which they call "X constituent." It was thought to be a ternary compound containing iron and silicon and could be observed under the microscope as dark particles. Dix4 has published unetched photomicrographs of an aluminum with 0.51 per cent. iron, 0.99 per cent. silicon, and 0.32 per cent. copper that shows three constituents: the dark Si (black in the figure), the lighter FeAl3, which appears in half tone and crystallizes in needles, and a constituent of the same color as FeAl3 but of different crystal form, often resembling Chinese script. This last constituent, Dix thought, is a compound of Fe and Si; not the compound FeSi but a compound containing a relatively small amount of silicon. Therefore an alloy of aluminum, iron, and silicon (the copper should not be regarded in the following considerations) must contain the following four constituents: Al, FeAl3,

Jan 1, 1926

GRAHAM BRIGHT,* East Pittsburgh, Pa.-Bee-hive coke ovens are usually located at the mines, where the gases from the ovens are not strongly objectionable because the communities are not thickly built up. The byproduct oven will naturally he located near centers of industry, to which the coal can be brought from different directions and desirable mixtures can be made; where also the byproducts can be readily marketed, while the gas can be utilized for industrial and domestic purposes. Not much thought seems to have been given to the gases escaping from the byproduct coke oven, which are more or less objectionable in thickly populated sections. When the byproduct oven shall have been more widely installed, this question is likely to become serious, and it will be necessary to apply remedies. May I ask what has been done, or is going to be clone, in this direction? S. A. Moss, ? Lynn, Mass.-One cause of escaping gas is that the gas exhausters do not supply the proper suction. If a satisfactory regulating governor is applied and the correct kind of gas exhauster is used, the trouble will be eliminated. J. I. THOMPSON,? Pittsburgh, Pa.-The hoppers Co. has made a careful study of the question of smoke prevention. The smoke caused by the operation of the byproduct coke ovens is infinitely less than that caused by bee-hive ovens.

Jan 11, 1918

By John Roberts

THE Federal income tax law permits as a deduction in determining net income "in the case of mines, . . . a reasonable allowance for depletion and for depreciation of improvements, according to the, peculiar conditions in each case, based upon cost, including cost of development not otherwise deducted: Provided, that in the case of such properties acquired prior to Mar. 1, 1913, the fair market value of the property (or the taxpayer's interest therein) on that date shall be taken in lieu of cost up to that date." The law provides for a reasonable allowance but the regulations provide for a definite method of computation that possesses more the virtue of simplicity than that of reasonableness. Article 210 of Regulations 45. reads: "When the cost or value as of Mar. 1, 1913, or within 30 days after the date of discovery of the property shall have been determined, and the number of mineral units in the property as of the date of acquisition or valuation shall have been estimated, the division of the former amount by the latter figure will give the unit value for purposes of depletion, and the depletion allowance for the taxable year may be computed by multiplying such unit value by the number of units of mineral extracted during the year." This is simple, but is it reasonable? The intent of the law is clearly that the cost of the ore in the ground shall be considered as part of the cost of the same ore when removed and sold. The regulations fail to carry out that intent, because of the unwarranted assumption that all the ore in the mine cost the same amount per ton. This is what gives the Treasury Department's method its simplicity, but at the same time robs it of its reasonableness because the assumption is contrary to fact.

Jan 1, 1921

By J. Paces, E. Miller, K. L. Komarek

The resistivity was determined as a function of temperature over the composition range from pure cadmium to 40 at. pct Cd. Melts with cadmium contents less than 85 at. pct had negative temperature coefficients of resistinity. On cooling below a transition temperature close to the liquidus temperature, the slope of the resistivity-temperature curve changed sharply. The activation energy calculated from the slope was 0.07 ev above the transition temperature and 0.14 ev below. The resistivity vs composition curve shows two maxima corresponding in composition approximately to CdSb and Cd3Sb2. THE relationship between the structure of a liquid and that of the crystal formed on solidification is at present not well-under stood. Various experimental determinations of the properties of liquids indicate that deviations from random atomic arrangements in liquids occur and that the properties of a solid and of its melt are closely related. Thermody-namic activities of liquids usually show negative deviations in systems where compound formation occurs in the solid,' and X-ray data indicate that close-packed solids and their melts frequently have nearly the same coordination number. Electrical resistivities and viscosities of liquids frequently exhibit maxima at compositions corresponding to compounds in the solid state. It should be of interest to study systems which have both stable and metastable compounds in the solid, and to determine if the short-range order in the liquid is affected by the existence of the metastable solid phase. The Cd-Sb system exhibits such a metastable phase. The phase diagram is shown in Fig. 1.3 The stable system has one intermetallic compound, CdSb, crystallizing in the orthorhombic crystal structure, with a melting point of 456°C. The metastable system also has one compound, Cd3Sb2, melting at 420°C and crystallizing in the monoclinic structure. Metastable alloys transform to the stable crystal structure in the temperature range from 250o to 350°C. Several distinct indications of very strong short-range order in the liquid phase have been reported in this system, with a close relation between the ordering in the liquid and the existence of both the stable and metastable solid phases. Scheil and Baach4 have observed distinctly different vapor pressures for liquid Cd-Sb alloys depending on whether the liquid solidified to the metastable- or stable-phase configuration. They observed an unusually sharp increase of the activity in a limited temperature interval immediately above the liquidus temperature of stable alloys, followed by a sudden decrease in slope to what they considered normal values. On cooling, the activity data reproduced the values in the normal range but then deviated from the values obtained on heating. They also observed that specimens of the stable phase upon melting and resolidifying always crystallized in the stable crystal structure as long as the melt was not heated to more than 485° to 525°C; otherwise solidification to the metastable phase occurred. However, in a later investigation, these results were not reproduced (13). The resistivity of liquid Cd-Sb alloys has been investigated by Matuyama 5, Oleari and Fioram, 8 and Belaschenko (141, but only above 500°C, the temperature region where Scheil and Baach observed no vapor-pressure anomalies. The data of Matuyama and of Oleari and Fiorani are reproduced in Fig. 5 and show a maximum in resistivity at 50 at. pct Cd. The data of Oleari and Fiorani, however, show the maximum as being rounded, and their values in general are slightly higher than those of Matuyama.

Jan 1, 1964

By George S. Rice

Instantaneous outbursts of gas in underground workings are similar in effect to great blasts of explosives, but without heat effects. Fortunately they occur only in a few localities in exceptional coal fields of the world and under exceptional geologic conditions. Such violent outbursts should not be compared with the ordinary outflows of gas into coal mines or with explosions of gas and dust. The phenomenon is essentially one of gas held in circumscribed areas under very high pressure and as a mining face or heading approaches such a place and the mining excavation sufficiently weakens the natural surrounding dam or shell, this is burst by the pressure just as by the discharge of a mass of explosives. The outbursts, so far as known to the writer, have been confined to coal beds and have not occurred in other mineral deposits. Hence, as discussed later, he believes that it is the relation of the gases to the coal material that is a factor in conjunction with others in producing conditions which permit the phenomena to occur when mining is done. The gases in most instantaneous outbursts have been hydrocarbon gases but in two coal fields they have been definitely found to be chiefly or wholly carbon dioxide. One of these localities in which CO2 outbursts have been frequent and have caused loss of life is in the southern part of the Gard basin, near Alais, in southern France. In 1919, the writer visited the Fontaine mine in this field the day following the occurrence of an outburst by which two men were smothered by carbon dioxide and fine dust. After 24 hr. the CO2 had not been entirely removed by the ventilating current. Occasional outbursts of CO2 have also occurred in other small basins in France, causing accidents, as in Puy-de-Dome. However, mines in the Gard basin, north of those in which CO2 outbursts have occurred, have experienced hydrocarbon gas outbursts. In the Lower Silesian coal field, Germany, there is a group of mines which have been subject to many instantaneous CO2 outbursts, some causing serious accidents, but the greatest disaster occurred recently

Jan 1, 1931

By J. H. Lightfoot, Stuart E. Buckley

DEEP drilling has led to the development of numerous pools which yield products consisting predominantly of natural gas accompanied by high-gravity water-white or slightly straw-colored liquid. Yields of this "condensate" or "distillate," as it is commonly called, vary from traces to over a hundred barrels per million cubic feet of gas. The fact that this liquid exists in the reservoir as an integral part of the gas phase and is formed by condensation attending simultaneous reduction of pressure and temperature after its entry into the well was apparently first recognized about 1932.1 The nature of the physical phenomena involved in this condensation was clarified for the petroleum industry in 1933 by a report by Sage, Schaafsma, and Lacey2 of the results of an experimental investigation of the behavior of mixtures of methane and propane. Search of the literature has revealed that the condensation of liquid from gaseous mixtures by isothermal pressure reduction is not a new discovery. Kuenen was led by theoretical considerations to expect such a phenomenon, and in 1892 reported3 the results of experimental verification of his deductions. This was followed by a considerable amount of work on the phase relations of mixtures by Kuenen4,5,6 and by others,7,8 mostly in European universities. Since 1930 investigators in this country have reported experimental data on the properties and behavior of a number of hydrocarbon systems.9-17 It is now generally known that in the presence of natural gas the solubility in the gas phase of the heavier and normally liquid hydrocarbons increases rapidly with increasing pressure above 500 to 1000 lb. per sq. in. Thus, at pressures of 2500 lb. per sq. in. or higher a gas may contain appreciable quantities of hydrocarbons with normal boiling points as high as 600°F., which in turn may be condensed from the gas phase by the reduction of their solubility therein attending pressure reduction. The combined effects of pressure and temperature on condensation and vaporization of mixtures are most readily visualized by the study of phase diagrams. Since the construction, application, and interpretation of such diagrams have been described fully in readily available literature, 18-20 this paper will not review the theoretical aspects of this subject. While the behavior of gas-distillate systems is now clearly understood, at least in a qualitative way, most of the published work deals with the results of laboratory studies of binary systems or of synthetic mixtures of hydrocarbons, and although several systematic investigations of the effects of separator pressure and temperature on the yields of liquid product from gas-distillate wells have been made21.22 it appears that in all cases the limitations have precluded the construction of even approximately complete phase diagrams for naturally occurring systems. There has

Jan 1, 1941

By William G. Schultz

Sylvite’s potash mine probably ranks as one of the most highly mechanized and automated mining operations in the world. Employing, on a normal 10-hr production shift, one supervisor and a crew of seven operators, Sylvite is able to mine at an average rate in excess of 600 tph. The ore is produced by two Marietta miners weighing 258 tons, making them the largest and heaviest piece of equipment ever taken underground. The ore produced by these two Marietta miners is conveyed to the shaft area, cycled through a 15,000 ton storage system and hoisted to surface completely automatically. The operation of all equipment in the mine can be monitored and controlled from a central control panel located underground.

Jan 7, 1972

By Arthur L. Christenson, Clarence E. Jackson

In the establishment of the relationship between weldability and hardenability, two methods have been employed in correcting for the grain growth produced in the heat-affected zone: first, the hardenability calculated from chemical composition* may be corrected to the grain size observed in an actual weld? or, second, a hardenability test may be made on the steel quenched from a temperature high enough to produce a grain size comparable to that found in the heat-affected zone.8 In order to obtain grain sizes in the end-quench hardenability bar comparable to those resulting in the base metal from the welding cycle, a quenching temperature of 2Ioo°F. has been used. In studies of the end-quench hardenability specimen quenched from 2Ioo°F. instead of from a lower temperature of I7OO°F., it is impor-TaiiT to ascertain The relative cooling rates for various distances along the bar. It is a question as to whether the cooling occurs at the same rate or whether there is any significant difference from the standard cooling-rate curve published by Jominy and confirmed by others.4,5 This paper reports experimental evidence concerning the effect of quenching temperature on the cooling rates in the end-quench hardenability test. The effect of quenching temperatures on cooling rates has been studied by a number of investigators.6'7 French has considered this effect from both theoretical and experimental aspects. In French's studies on complete quenching of spheres and rounds, an increase in the quenching temperature caused an increase in the cooling rate at 720°C. at the center of the specimen. The center cooling velocity also has been shown to be dependent upon the surface per unit volume for the type of specimens studied; the velocity of cooling increases with an increase in the surface per unit volume. Three methods of indicating the rapidity of cooling of a body of metal during a quenching operation have been propped: I. The time it takes for the metal to cool from the quenching temperature to a temperature halfway between the quenching temperature and the temperature of the quenching medium (half-temperature time): Grossmann, Asimow and Urban7 justify the use of this criterion by the fact that the half-temperature time includes the temperature and time of incubation as well as the zone of formation of pearlite and, further, the data so derived accord very closely with experimental values. 2. The time interval the metal remains in a given temperature range; for example,

Jan 1, 1944

By Arthur L. Christenson, Clarence E. Jackson

In the establishment of the relationship between weldability and hardenability, two methods have been employed in correcting for the grain growth produced in the heat-affected zone: first, the hardenability calculated from chemical composition* may be corrected to the grain size observed in an actual weld? or, second, a hardenability test may be made on the steel quenched from a temperature high enough to produce a grain size comparable to that found in the heat-affected zone.8 In order to obtain grain sizes in the end-quench hardenability bar comparable to those resulting in the base metal from the welding cycle, a quenching temperature of 2Ioo°F. has been used. In studies of the end-quench hardenability specimen quenched from 2Ioo°F. instead of from a lower temperature of I7OO°F., it is impor-TaiiT to ascertain The relative cooling rates for various distances along the bar. It is a question as to whether the cooling occurs at the same rate or whether there is any significant difference from the standard cooling-rate curve published by Jominy and confirmed by others.4,5 This paper reports experimental evidence concerning the effect of quenching temperature on the cooling rates in the end-quench hardenability test. The effect of quenching temperatures on cooling rates has been studied by a number of investigators.6'7 French has considered this effect from both theoretical and experimental aspects. In French's studies on complete quenching of spheres and rounds, an increase in the quenching temperature caused an increase in the cooling rate at 720°C. at the center of the specimen. The center cooling velocity also has been shown to be dependent upon the surface per unit volume for the type of specimens studied; the velocity of cooling increases with an increase in the surface per unit volume. Three methods of indicating the rapidity of cooling of a body of metal during a quenching operation have been propped: I. The time it takes for the metal to cool from the quenching temperature to a temperature halfway between the quenching temperature and the temperature of the quenching medium (half-temperature time): Grossmann, Asimow and Urban7 justify the use of this criterion by the fact that the half-temperature time includes the temperature and time of incubation as well as the zone of formation of pearlite and, further, the data so derived accord very closely with experimental values. 2. The time interval the metal remains in a given temperature range; for example,

Jan 1, 1944

By R. J. Jones, L. D. Clark, R. C. Howell

This research provides an empirical approach toward further analysist10 of the variables in rock breakage under direct, hydroimpact (impacting on fluid) and explosive impulse loading. That the strain on the face of a block of rock, below an impact pin or explosive charge, is directly proportionate to the rupturing force F and inversely proportionate to the product of the burden W and the hole periphery S, is borne out in the laboratory using electrical resistance strain gages to measure a peak strain during rupture by small explosive charges detonated in boreholes. Furthermore, such findings established the validity of the expression F = Ss • Wy • R as a useful relationship from which, it is believed, can be derived practical applications in commercial rock blast design.

Jan 1, 1972

By Chester Lee

Introduction THE Atlin Mining District is in the northwest corner of the Province of British Columbia. Ruby Creek, where the operation to be described is situated, is 17 miles east of the town of Atlin and about 18 miles south of the south line of Yukon Territory (Fig. 1). Gold was discovered in the district in January, 1898, and the production to date from placer mines has been $4,518,000, according to the reports of the Minister of Mines for-the province. Geology The essential points in the regional geology are given in the following paragraphs. Long erosion produced a plane-like surface slightly above sea level with a few peaks and ridges.1 A gradual uplift followed and. erosion increased, the streams cut deeper, the cuts so made being afterward increased by glaciation. The ice straightened and planed the slopes of the main valleys and widened and lowered their floors, in some cases flooring the valleys with silt, sand, gravel, and clay. As the glaciers rapidly retreated, lakes were formed.

Jan 5, 1916

By Frank Harwood Riddle

Products made from the ores of the sillimanite group, and synthetic substitutes for them, have unique properties, and service tests prove that they are playing, and will continue to play, a major part in improvements in metallurgical processes. Also, they are examples of how comparatively useless, rare, or "museum" minerals have been made available in commercial quantities. Until research developed uses for them, the minerals had been observed only in small, scattered masses, or crystals. Improvements in ceramic processes and compositions have come about very gradually. In the last 10 or 15 years, several outstanding developments have been made. Of greatest interest to the mining and metallurgical engineers are those affecting the composition, necessitating the mining of new minerals, and improvements in ceramic products used in metallurgical processes. Sillimanite and Mullite Sillimanite (Al2O3.SiO2), then known as Fibrolite, according to Dana,' was first reported in 1792. In 1796, cyanite (Al2O3.SiO2) was first described.2 In 1873, Behrens published results of his microscopic study8 of porcelain. He showed that it contained what appeared to be crystals, which dissolved less readily than quartz and glass in hydrofluoric acid. Hussak4 described the presence of needlelike crystals as occurring in some instances in small amounts in certain porcelains. In 1908, Plenske and Zoellner both studied porcelain structure.5 Plenske observed that "sillimanite" might be present in masses of exceedingly minute grains which apparently were amorphous. Zoellner advanced the theory that the needlelike crystals were formed by a molecular change in the clay,

Jan 1, 1932

By C. K. Ferguson, J. A. Klotz

This paper describes experimental investigations conducted at the California Research Corporation's model oil well. The first part describes filter loss from several drilling muds through bore hole walls during mud circulation and drill string rotation. The effect of mud properties and drill string rotation with mud circulation is described. Filtration from a bore hole full of drilling mud, not circulating, but under pressure for extended time periods, is also discussed. The second part describes filter loss to permeable formations from beneath a drilling bit where filter cuke has no opportunity to develop appreciable thickness. If potential flow theory is applied to predict filtrate invasion from this hole bottom, targe invasions arc calculated. But model well experimentation shows that filtrate invasion from the hole bottom is controlled by mud particles that penetrate the formation ahead of the bit. This experimentation provides data to estimate the effect of mud particle penetration on fluid loss to formation. The third part presents an estimate of mud filtration during drilling of a well. INTRODUCTION As oil wells are drilled by the rotary method, drilling mud circulates up the annulus between drill pine and well wall. Drillers adjust mud density so that the pressure at the bottom of the mud column is several hundred psi greater than the pressure of reservoir fluid. As a result of this pressure difference, the liquid part of the mud filters into the rock around the bore and mud solids deposit as a filter cake on the well wall. For many reasons the petrogleum industry, within the past 20 years, has spent much money and energy to determine the volume of mud filtrate that enters rock around the well bore and dedicated much research effort to reduce this volume. Among the reasons for attempts to determine the volume of mud filtrate and to reduce this volume are the following: 1. If filtrate damages the permeability of oil sand, the resultant damage to oil well productivity will depend on the distance that the filtrate invades the oil sand; reduction of filtrate volume may, therefore, increase well productivity. 2. Filtrate that penetrates shale sections may cause the shale to swell and to slough into the well bore. Uncontrolled sloughing may stick drill pipe. Reduction in filtrate volume may reduce drilling trouble. 3. Electric log resistivity curves are changed by invasion of a mud filtrate; the change depends on the depth to which filtrate invades. Knowledge of this depth is necessary before resistivity logs can be interpreted accurately. For these reasons, specifications the place an upper limit to drilling mud filter loss are now written into almost all drilling programs. These specifications are based on APT Recommended practice 29, Standard Field Procedure for Testing Drilling Fluids,' which describes a static filtration test operated at 100 psi filtration pressure and at ambient temperature. Although this test is adequate for mud control, it cannot be used to compare filtration properties of different muds. Schremp and Johnson' showed, for example, that mud with a low API filter loss does not necessarily have low filter loss at bottom hole temperature and pressure. Also, no information has been available about the effect of bottom hole mechanics (mild circulation, drill string rotation, and bit action) on mud filtration. This paper discusses filtration data measured in the California Research Corporation's model oil well, which models closely oil well bottom hole geometry and hydrodynamic conditions. The filtration processes that

Jan 1, 1955

By C. F. Floe, M. Cohen, M. B. Bever, V. G. Paranjpe

P. Coheur and L. Habraken—We read this paper with great interest and are glad to congratulate the authors for their valuable work, supplying an important contribution to the mechanism of tempering on the carbides in vanadium steels. We are in a good position to appreciate this work since we have been studying, for more than a year, Cr-Mo steels of a composition similar, but less highly alloyed (namely 0.1 pct C, 3 pct Cr, 1 pct Mo). Our results are quite in concordance with the authors', however, we wish to point out that it is very interesting to use equally the electron microscope in order to observe the variations of microstructure in steels. We have studied simultaneously the evolution of the carbides in situ with the electron microscope, and, after extraction, again with the electron microscope, and then with X-rays. The first results which we have obtained have been communicated at the Congress of Delft (July 1949) and at the "Journees de la Metallurgie" in Paris (October 1949). These may be summarized as follows: After tempering with varying either the tempering temperatures or the tempering times, the carbides show two evolutions. The first one is connected to the carbides existing in the steels, principally in the boundaries of the grains. For some groups of steels these carbides may coalesce and for other groups they may

Jan 1, 1951

By N. J. Grant, D. S. Bloom

P. Coheur and L. Habraken—We read this paper with great interest and are glad to congratulate the authors for their valuable work, supplying an important contribution to the mechanism of tempering on the carbides in vanadium steels. We are in a good position to appreciate this work since we have been studying, for more than a year, Cr-Mo steels of a composition similar, but less highly alloyed (namely 0.1 pct C, 3 pct Cr, 1 pct Mo). Our results are quite in concordance with the authors', however, we wish to point out that it is very interesting to use equally the electron microscope in order to observe the variations of microstructure in steels. We have studied simultaneously the evolution of the carbides in situ with the electron microscope, and, after extraction, again with the electron microscope, and then with X-rays. The first results which we have obtained have been communicated at the Congress of Delft (July 1949) and at the "Journees de la Metallurgie" in Paris (October 1949). These may be summarized as follows: After tempering with varying either the tempering temperatures or the tempering times, the carbides show two evolutions. The first one is connected to the carbides existing in the steels, principally in the boundaries of the grains. For some groups of steels these carbides may coalesce and for other groups they may

Jan 1, 1951

By C. B. Alcock, R. A. Oriani

Some simple models of solutions are described; these include the regular solution, the subregular solution, and the quasichemical model. The assunzption underlying these models, the physical signzficance thereof, and the experimental manifestations are discussed. Examples are presented from the fields of liquid and solid metallic solutions, liquid slags, mattes, liquid and solid ionic solutions, and mixed carbides to show under what conditions and for which systems these solution models are fair descriptions. The deviations of real solutions from the models are of theoretical interest. Some such deviations, both for dilute and for concentrated solutions, arc pointed out and their Physical sigtzzficance discussed. DURING the past half century there has been a gradual accumulation of thermodynamic data for systems of interest to the metallurgist. There remain many gaps in the data, however, and the metallurgist must often face the problem of estimation of thermodynamic quantities where measured values do not exist. One might hope that the experimental progress would be matched by theoretical advances which would make such estimations possible with a high degree of confidence. However, theoretical progress has been disappointingly slow even for the simplest kinds of solutions, and since the multicomponent systems in which the metallurgist is interested are very complex, one cannot expect theory to be of much help to the metallurgist. In this situation, therefore, it seems worthwhile to examine some simple models of solutions from two points of view: firstly, to see if such crude models represent the thermodynamic facts in as many types of solutions as possible sufficiently well for the needs of the metallurgist, and secondly to see what the deviations from such models show to be important for consideration by theorists. BOND ENERGY MODELS OF SOLUTIONS The simple models that we will examine from these points of view may be termed statistical models, in that they are concerned with the thermodynamic consequences of some simple assumptions about the energy of an assembly of atoms, molecules, or ions, and do not inquire into the physical basis of the interaction. The underlying assumption of these models is that the energy of an assembly of molecules (by which we include also atoms or ions) is given by the sum over all interaction energies of molecules taken two at a time; we will discuss only those models in which the pairwise interactions are restricted to those between nearest neighbors. Thus, in a pure substance of bond energy EAA, the internal energy (with respect to some specific reference state) will be expressed as NAA EAA where NAA is the number of nearest-neighbor pairs. A solution of molecules A and B will be characterized by NAA EAA + NBB EBB + NAB EAB where the Eij represent the bond energies of the nearest-neighbor i-j pairs. If one assumes that the EAA and EBB are the same in the pure components as in the solution, and that the coordination numbers in the two pure substances and in the solution are the same, then the energy of the solution with respect to the pure components (i.e., the energy of solution) is a function of the following linear combination of the bond energies: EAB - 1/2(EAA +EBB) = w. The thermodynamically ideal solution is defined as one in which the activity of each component is equal to the mole fraction of that component at all concentrations and all temperatures. It follows that

Jan 1, 1962

By Alan T. Gorton, T. L. Joseph, Gust Bitsianes

High-temperature X-ray diffraction techniques were used to determine thermal expansion coefficients of iron and its oxides. Lattice parameters of a and iron, wiistite, magnetite, hematite, and goethite were determined and plotted as a function of temperature. From these results, the true and mean linear thermal expansion coefficients were calculated. In the case of noncubic crystals, the expansion coefficients were determined along each of the crystallographic axes. The effect of the magnetic transformation on lattice parameter was measured for a iron and magnetite at their respective curie temperatures. COEFFICIENTS of expansion for iron and its oxides were determined from the temperature dependence of their lattice parameters. From these data, the true linear coefficients were derived by means of the formula: at =[(l/ao )(dao/dt)] [1] where at is the true linear coefficient of expansion, a, is the lattice parameter in angstrom units, and all variables are referred to the temperature, t, in OC. Thus the true expansion coefficient represents the instantaneous change in lattice parameter on a unit basis and at a particular temperature. A second expansion coefficient is also often used. It is termed the mean linear coefficient and is defined in the following way: am = [ao(t) - ao(O)]/ao(0) l [21 This coefficient represents the average change in lattice parameter on a unit basis but at a specified parameter length, ao at O°C, and over a specified temperature range,1 to 0°C. Generally the true co-

Jan 1, 1965