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By A. S. Eve

In the spring of 1930, the question was raised as to the possibility of estimating the depth to which the pyrrhotite-nickel deposit at the Falconbridge mine extended in the earth. This body is 7500 ft. long, it dips at 80° to the north, and it is fairly straight with slight sinuosities. Dr. F. W. Lee suggested that it might be possible to solve the problem by measuring the vertical magnetic intensity, with a good magnetometer, both near the surface of the earth and also at a level a few feet higher in the air. The writer regarded this suggestion with some scepticism, but it was decided to put the scheme to a practical test. In July, 1930, Dr. Lee, Dr. Keys and the writer, with Mr. Joyce and Mr. Belloc as assistants, made a firm, light wooden platform (Fig. 1) measuring 4 by 4 ft. on the top, which was 10 ft. above ground. This platform could be moved easily a few yards by four men, and carried across country in a wagon or by motor truck. Some iron nails were used in its construction, but we were not able to detect their influence on the Askania magnetometer. Nevertheless, in future work, the use of iron should be completely avoided. Readings were taken along a traverse at right angles to the orebody, at several stations, both on the ground and on the platform. The excess readings, over the dike, as compared with those about 800 ft. away, are shown in Table 1. The largest reading, 6.8, is open to suspicion and should be rejected. The depth of the top of the orebody is known by electrical survey, and by actual drilling, to be about 112 to 123 ft., and the covering is sandy glacial drift. Similar readings were taken over a long straight magnetic diabase dike. These also are shown in Table 1. The magnetic vertical intensity is consistently less at the higher level, which is 10 ft. above the lower level.

Jan 1, 1932

By Raymond E. Birch, Oscar M. Wicken

THE mineral magnesite, formerly the source of nearly all magnesia, now shares this role with brucite, dolomite, and the world's natural and artificial brines. The mineral magnesite is the normal carbonate of magnesium, MgCO3, composed when pure of 47.6 pct MgO and 52.4 pct CO2. It is one of the calcite (CaCO3) group of rhombohedra1 car- bonates, which also includes dolomite, CaCO3.MgCO3, and siderite, FeCO3. Magnesite does not form an isomorphous series with calcite or dolomite; consequently, these lime-bearing carbonates commonly present in magnesite deposits are there only as mechanical mixtures. Magnesite and iron carbonates form a continuous isomorphous series and therefore are inseparable mechanically. The variety of magnesite known as breunnerite is an isomorphous mixture of iron and magnesium carbonates. Magnesite may be either crystalline or amorphous (cryptocrystalline). The former, which includes breunnerite, is often termed spathic magnesite. Crystalline magnesite varies from finely to coarsely crystal- line in texture and has a hardness of 3.5 to 4. The color is white, yellowish, blue-gray to drab, red, pink, black, or mottled. It is seldom found pure but usually contains variable amounts of iron, lime, silica, and sometimes manganese. The color cannot be used as an index of purity. The cryptocrystalline variety is perhaps the more common type but the crystalline variety usually occurs in larger deposits. The amorphous type is fine grained and compact, showing no cleavage. It is usually snow white but sometimes is light to pale orange yellow or buff, owing to impurities. The fracture is conchoidal to uneven and the hardness 3.5 to 5. Silica may be present as inclusions of serpentine, quartz, chalcedony, or other minerals. The lime and iron contents are usually low. In general, amorphous magnesite is somewhat purer than the crystalline variety. The specific gravity of cryptocrystalline magnesite is 2.90 to 3.00. Pure crystalline magnesite has shown a specific gravity of 3.02 but iron

Jan 1, 1949

By E. C. Harder

BAUXITE is known mainly as the ore from which aluminum is smelted but it has large use also in the manufacture of artificial abrasives and as a basis for certain chemical industries. A small amount is used for refractories and for other purposes. COMPOSITION Dana and others give the mineral formula of bauxite as A1203.2H20 and the composition as A12037 73.9 pct; H2O, 26.1 pct. It has been definitely shown, however, that bauxite does not exist as a specific mineral but rather as a rock. The term is now used synonymously with aluminum ore and it embraces gibbsite (hydrargillite or alpha trihydrate), A1203.3H20 (A12037 65.4 pct; H2O, 34.6 pct); boehmite (alpha mono¬hydrate), A1203.H20(Al203) 85 pct; H2O, 15 pct); diaspore (beta monohydrate), A1203.H2O(A12037 85 pct; H2O, 15 pct), and mixtures in various proportions of any two of them. Bauxite of the Mesozoic and Cenozoic in Europe is predominantly a mixture of gibbsite and boehmite, subordinately a mixture of boehmite and diaspore, or gibbsite and diaspore. The bauxite of North and South America, tropical Africa, Asia, and Australasia consists largely of gibbsite. Corundum (A1203) is not included under bauxite, although gradations from bauxite to emery or corundum exist. All bauxite, irrespective of the aluminum minerals composing it, contains certain impurities, including silica, in the form of clay minerals (kaolinite, halloysite, and others) or quartz, iron oxide (as hematite or goethite), titania (as leucoxene or rutile), iron sulphide (as pyrite or marcasite), iron carbonate (siderite), and calcium carbonate (as calcite); the last three mentioned in minor amount and of local occurrence only. Bauxite belongs to a group of partly consolidated materials called laterites, formed by surface weathering. This group includes also impure siliceous and ferruginous bauxite and siliceous and

Jan 1, 1949

By T. Kunitake, H. W. Paxton

The self-diffusion coefficient of chromium in various alloys in the iron-chromium system has been measured. A variation in Dofrom 10-4 for pure chromium to a maximum of 102 near 60 pct Cr appears with a range of activation energy from about 50 to 80 kcal per mol. The general pattern of behavior observed is not consistent with present theories of diffusion by a vacancy mechanism. Suggestions are made for further clarifying experiments. RECENT work on the self-diffusion of chromium,' ?-uranium2-4 and ß-zirconium,23, 26 has indicated that these elements have very low Do (10-3 to 10-4) compared to that conventionally expected for vacancy diffusion. Pound et al.5 have suggested that this may be due to ring diffusion being operative, and have proposed a model which gives Do of the correct order of magnitude. The essential difference between this model and Zener's earlier model6 is that whereas Zener assumes tight coupling between atoms in a ring to establish a vibrational frequency, Pound's model allows the atoms to vibrate essen- tially each in their own normal modes. The probability of each atom moving in the correct direction to cause a ring of n atoms to rotate by 2p/n must then be calculated as a "synchronal entropy" which may be -20 e.u. for a 4 atom ring. In iron, the latest determinations of self-diffusion yield Do in the range 18 to 522.7-9 The most accurate is probably that of Borg and Birchenall8 which is 118 ± 3. This value is not inconsistent with that expected for a vacancy mechanism. Since iron and chromium are very closely similar in size, are both transition metals, and their solution is thermodynamically ideal at temperatures of interest in diffusion, it appeared that a determination of self-diffusion coefficients, Do and Q as a function of composition would be of substantial interest to diffusion theory. The following measurements were made with this purpose in mind.

Jan 1, 1961

By G. B. Gibbs

Equations are developed which describe the growth of graphite nodules during a-phase graphi-tization under various limiting conditions. When carbon diffusion is rate controlling a modified Birchenall-Mead equation predicts an "apparent activation energy" of 31 keal mole-1 for the parabolic growth constant. If reaction at the graphite or cementite interface is the slowest process growth kinetics are linear and the activation energy must be >50 keal mole-1. A comparison with the experimental observations confirms that carbon diffusion determines the rate of reaction. Apart from minor approximations associated with Lou! carbon solubility in a iron the theory may also be applied to I-phase graphitization. It is well-known that cementite exists as a meta-stable phase in Fe-C alloys and that if a specimen is held at diffusion temperatures for a sufficiently long period the cementite decomposes and graphite is precipitated. Graphitization occurs by the nu-cleation and growth of carbon nodules and several impurity elements catalyze the reaction when present in minute amounts.1 The growth kinetics of nodules have been extensively investigated in the fee ? range2, 3 and recently in the bee a range.1, 4 Experimental growth curves (nodule radius vs time) have slopes which decrease with time, but the scatter of points is generally too great for the precise shape of the curves to be determined with certainty. Birchenall and Mead5 concluded that they are parabolic in ? iron, indicating diffusion control, and that the migration of carbon atoms determines the growth rate. Harris et al, 1 advanced similar ideas for a-phase graphitization. On the other hand, Burke3 chose to regard the initial growth region as a transient followed by a linear law indicating interface control (i.e., cementite decomposition or graphite crystallization as the slowest process). Jeminson and Higgins6 originally considered the initial steep portions of "parabolie" to represent a linear growth law also. In support of these ideas it has been noted that the apparent ac-

Jan 1, 1965

By Homer W. Riley

ANTHRACITE SMALL power-driven, toothed, cast-iron rolls were used first to break anthracite in 1844. Prior to that time, men with hammers, who stood on perforated cast-iron plates, broke the large lumps into commercial sizes. In order to convert run-of-mine into the various sizes required by the anthracite industry, about 20 million tons must be broken, annually, into smaller sizes. This phase of anthracite preparation is of major importance, because the degradation accompanying reduction in coal sizes should be kept at a minimum. The exclusive use of toothed rolls for that purpose indicates that comminution by rolls is the best solution of the problem. Many improvements have been made in tooth design, but the most important was a reduction of the peripheral speed of the rolls from 1000 to 300 ft. per minute. The higher speed was based upon and approximated the velocity of a falling piece of coal when it entered the rolls, Exhaustive roll tests at the slower speed showed that the same size reduction could be affected with less degradation. The adoption, therefore, of slow-speed, compound geared rolls, especially for breaking the larger sizes, became quite general after 1912. A high-speed roll is shown in Fig. 1 and a slow-speed roll in Fig. 2. Anthracite Crushing Problems.-Crushing anthracite presents the problem of selecting a series of rolls that will produce the greatest percentage of the prepared sizes of nut and over. The size distributions to be expected are shown in Table 1. Coal breaking and crushing practices in anthracite breakers involve the use of equipment for comminuting the following classes of material: 1. Run-of-mine-plus 6 ½ -in. coal. 2. Sized coal-steamboat, broken, egg, stove, nut, and pea. 3. Flat coal--coal that is flat and hence not suitable for the market. 4. Bone--a piece of laminated coal and slate, crushed for the purpose of reclaiming the coal. 5. Breaker refuse, reduced to a size suitable for flushing into a mine for back-filling purposes.

Jan 1, 1950

By P. H. Brace, N. A. Ziegler

The study of the relations between gases and metals is one of pcren-nial interest to all who are connected with the production of high-grade metallurgical products. The data reported here are the outcome of work of which the object is to determine the effects of dissolved gases upon the properties of metals and to gain a more detailed knowledge of the reactions between gases and molten metals, particularly iron, under definitely controlled conditions. We have attempted to reduce our margin of error by dealing with relatively large quantities of metal, from 4 to 13 Ih. (2 to 6 kg.), and keeping the ratio of refractories to metal as small as practicable. The ingots produced are large enough to provide adequate material for making determinations of magnetic and other physical properties. In choosing the bell-jar type of furnace we were influenced by the results of considerable experimentation along the same general line which indicated that, for the scale on which we were to work, it was important to have the furnace structure independent of the vacuum enclosure. The use of a bell-jar surrounding the entire furnace accomplishes this and also gives great freedom of observation during operation and ready accessibility for the replacements which are necessary after each run. Our choice of analytical method was made in the light of the results secured by H. M. Ryder, who used a method similar in principle for the analysis of very small quantities of gas extracted from strips of metal heated electrically in high vacuum. We have presented some selected preliminary experirnental data as being illustrative of the quantity and nature of the gases which occur in iron of different origins, but do not urgc any hypothesis at this time. The Furnace Our furnace may be described as "a high-frequency induction furnacc of the bell-jar type." It is similar in a general way to that described by Cain and Peterson1 though we have introduced certain refinements of

By R. P. Rothwell

The milling of silver ores has arrived at a great degree of perfection in the mining districts of our Western States and Territories, and I hare thought the record of the practical results obtained at the present time, in a few of the principal districts, would prove of value arid interest to many of our members, both at home and abroad. An American silver mill is composed, in descending order from where the ore is dumped, of: 1st. A rock-breaker, usually of the Blake or Alden pattern; 2d. The battery of stamps, the number of which varies from 5 to 120, generally in batteries of 5 or 10 heads, so arranged that a single battery may stand while the others are running; 3d. The tanks where the crushed ore settles (if it is a met stamping-mill), or of a drying-floor if the crushing is done dry; 4th. Amalgamating pans ; 5th. Settling pans ; 6th. Agitators or pans in which mercury escaping in the tailings is caught; 7th. Blanket sluices, over which the tailings run, and where mercury and unamalgamated sulplides are saved. A reference to the engravings (see plate), which show one of the latest forms of an 80stamp silver-mill run by a turbine water-wheel, will show clearly the arrangement of the several parts. THE ONTARIO, UTAH, SILVER MILL. One of the best examples of a silver-mill, and at the same time one of the most successful concerns in the West, is the mill of the Ontario Silver Mining Company, near Salt Lake, in Utah. This mill treats the ore from the Ontario mine, ore which at present is very base, being composed of zinc, lead, and silver sulphides and silver chloride in a quartz gangue. This ore has become baser as the mine attained greater depth, though the vein holds its own, or rather increases, both in thickness and richness. The mill is managed in a skilful and economical manner, though the necessity for

Jan 1, 1880

By W. Mostowitsch

Lead sulphate occurs as anglesite, and is formed in every roasting of lead sulphides or sulpho-salts containing lead. In smelting in the blast furnace an ore containing natural or artificial lead sulphate, a large part of the sulphur present goes to the formation of the intermediary product matte which requires further treatment for the recovery of the values it contains. It is therefore of importance to study the behavior of lead sulphate at elevated temperatures, both without and with reducing agents, especially as the information available gives data which are more or less conflicting. 11. Decomposition of PbS04 by Heat The dissociation of PbSO4 into PbO and SO3 or SO2 and 0 has been discussed by many metallurgists. The following data are considered to be representative. Doeltz and Graumannl found that PbS04 was not affected-by heat at 800" C.; that dissociation began at 900" C., and was rapid at 1,000° when the salt lost in 1 1/2 hr. 14.3 per cent. of its weight, the dry salt containing 26.43 per cent. SO3. Hofman and Wanjukow2 summarize their work upon the dissociation of metallic sulphates with the statement that the decomposition of PbS04 begins at 195' C., but progresses very slowly, with the formation of the basic salt 6PbO.5SO3 at 705"; that this salt undergoes a transformation at 847") begins to be decomposed at 888") to sinter at 896", and to fuse at 910"; rapid dissociation begins at 952") and is accompanied by volatilization of PbO; retardations at 958" and 962" indicate an acceleration of decomposition which, however, is not complete. Proske3 found that PbSO4 gave off at 900" C. in 30 min. only 0.63 per cent. of its 803, and that the loss increased with

Jan 1, 1917

By J. B. Dyess, H. A. Miley

Tarnish films on some of the common metals (particularly on copper and silver) have been of much scientific and commercial concern for a long time, but before the development of the electrical method1 of measuring film thicknesses there was no satisfactory quantitative approach by which to study the separate parts of these complex films. This method has been adapted to the measurement of duplex (cuprous-cupric) oxide films on copper.2 In the present work it has been used to measure tarnish films on copper when they were mixtures of cuprous oxide and cuprous sulphide, and also when they contained cuprous oxide, cupric oxide and cuprous sulphide, each component part being measured at a different potential value. Oxide-coated copper specimens, prepared by heating copper in air at chosen temperatures for given periods, were exposed to moist hydrogen sulphide in air to forml the various oxide-sulphide films studied. The comparative resistances afforded by (I) different thicknesses of oxide films, and also (2) equal thicknesses of oxide and sulphide films, against severe attacks of hydrogen sulphide were measured. The electrical method requires that the time be observed for the cathodic reduction of each part of the film substance, and these respective time values multiplied by the constant current give the corresponding quantities of electricity expended. Then each millicoulomb per square centimeter represents a film thickness of M X 108____ 2DX 96,494 X 103 where M is weight of oxide (or sulphide) giving one gram-atom of oxygen (or sulphur) for cathodic reduction, D is density of the oxide (or sulphide) and t is the thickness in Angstrom units per millicoulomb per square centimeter. The value of t for cuprous sulphide (cubical) is 14.27, and is obtained by substituting 5.78 for D and 159.20 for M in equation a. Previous values hf t for cuprous and cupric oxides (12.36 and 6.39, respectively) were used in the present work.

Jan 1, 1939

By J. B. Dyess, H. A. Miley

Tarnish films on some of the common metals (particularly on copper and silver) have been of much scientific and commercial concern for a long time, but before the development of the electrical method1 of measuring film thicknesses there was no satisfactory quantitative approach by which to study the separate parts of these complex films. This method has been adapted to the measurement of duplex (cuprous-cupric) oxide films on copper.2 In the present work it has been used to measure tarnish films on copper when they were mixtures of cuprous oxide and cuprous sulphide, and also when they contained cuprous oxide, cupric oxide and cuprous sulphide, each component part being measured at a different potential value. Oxide-coated copper specimens, prepared by heating copper in air at chosen temperatures for given periods, were exposed to moist hydrogen sulphide in air to forml the various oxide-sulphide films studied. The comparative resistances afforded by (I) different thicknesses of oxide films, and also (2) equal thicknesses of oxide and sulphide films, against severe attacks of hydrogen sulphide were measured. The electrical method requires that the time be observed for the cathodic reduction of each part of the film substance, and these respective time values multiplied by the constant current give the corresponding quantities of electricity expended. Then each millicoulomb per square centimeter represents a film thickness of M X 108____ 2DX 96,494 X 103 where M is weight of oxide (or sulphide) giving one gram-atom of oxygen (or sulphur) for cathodic reduction, D is density of the oxide (or sulphide) and t is the thickness in Angstrom units per millicoulomb per square centimeter. The value of t for cuprous sulphide (cubical) is 14.27, and is obtained by substituting 5.78 for D and 159.20 for M in equation a. Previous values hf t for cuprous and cupric oxides (12.36 and 6.39, respectively) were used in the present work.

Jan 1, 1939

By L. C. Glenn

IN the preparation of this paper the writer has drawn freely upon the writings of Orton, Munn, Shaw, Mather, Miller, Hoeing, St. Clair, Jillson, and others, as well as upon his own personal knowledge of the fields of both states. It is to be regretted that certain data gathered by him and his assistants last fall are not available for publication. OIL IN TENNESSEE A few wells drilled for brine for salt making in Tennessee between 1820 and 1840 obtained oil, but no definite search was made for oil until just after the close of the Civil War. Active drilling was then begun in Overton and counties southwest of it on the eastern half of the Highland Rim. A number of strikes were made at shallow depths in the basal part of the Mississippian but the wells were soon exhausted and abandoned. Drilling was revived, about. 1892, when the Spurrier district in Pickett County was developed and was followed by the Riverton district in the same county in 1896. A pipe line was laid from the Wayne County, Ky., fields and about 60,000 bbl. of oil were run before a very heavy slump in the production, a failure to find an extension of the field, and excessive local taxation caused the removal of the pipe line in 1906. There was then no production in Tennessee until the discovery, in 1915, of oil near Oneida, Scott Co., at about 950 ft. (289 m.) in fissures in the Newman or St. Louis limestone. This field, however, soon failed and was abandoned. In 1916, oil was found at Glen Mary, Scott Co., in the Newman limestone at a depth of 1232 ft. (375 m.) A number of wells have since been drilled there, some of which were dry while others, close by, were producers. The largest one yielded, at first, about 340 bbl. per day and produced for several months, when it suddenly went dry. Several of the first wells began at 6 or 8 bbl. per day and are still maintaining that

Jan 1, 1920

By Karl Sundberg

ELECTRICAL investigations carried out in regions containing sedimen-tary rocks showed that sediments generally are good electrical conductors, a fact which at the present time is used for structural investigations by electrical methods. It is of fundamental importance, not only for these investigations but also for electrical prospecting in general, to know the electrical properties of various soils and rocks. It will be useful, there-fore, to discuss this question with the hope that the general points of view discussed in this paper will perhaps be, completed by further observations and determinations of material from various localities. This paper is based principally on the study of literature, and the purpose is primarily a discussion of the main factors that determine the electrical conductivity of soils and rocks. It will follow, however, that the factors discussed here also frequently decide how far a certain orebody can be regarded as a good electrical conductor compared with the sur-rounding rocks. All-rocks are more or less porous; and the pores are filled with liquids and gases. Their electrical conductivity, therefore, depends on the following factors: 1. The electrical conductivity of minerals composing the rock. 2. Electrical conductivity of the liquid filling the pores. 3. Proportion of the volume of liquid filling pores of the rocks to the solid rock material. 4. Shape of the pores. 5. Arrangement of the particles of gas and liquids. 6. Temperature. Dry minerals, with the exception of certain ore minerals, are complete nonconductors from the point of view of applied geophysics; in the present investigation we deal with rocks which have no conducting minerals, and factor 1, therefore, is not important. The same is true of soils. The liquids contained in soils and rocks in most cases are waters, some-times oil. As oil is a nonconductor of electricity, the impregnating waters will determine the electrical conductivity of soils and rocks.

Jan 1, 1932

By Douglas Bunting

IN THE anthracite fields of Pennsylvania, mine fires occur with more or less regularity and their existence is an ever-present hazard in coal mining. In all probability 90 per cent. of the mine fires can be ascribed directly or indirectly to the ordinary miner's open lamp. Other causes may be smoking, electrical installations, gas explosions, gas feeders, and the communication of fire to the outcrops from ash dumps, culm banks, timber and brush fires. Fires in pump rooms, engine rooms, and barns have been largely eliminated as a result of the Act of .Assembly, approved June 15, 1911, which provides that all inside buildings, including engine rooms, pump rooms, barns etc. shall be constructed of incombustible materials. Smoking of pipes, cigars, and cigarettes should be prohibited in the mines and too much care cannot be exercised in preventing fires by enforcing all rules designed for that purpose. Mine fires that involve underground fighting are invariably dangerous, and all fires, irrespective of the method pursued in extinguishing them, involve property loss and expense. Each fire generally presents a more or less original problem, dependent on the particular conditions. Generally mine fires may be divided into two classes: Those occurring in inaccessible workings and those occurring in accessible workings. The methods pursued in extinguishing or controlling mine fires are as follows: (1) direct attack, (2) smothering by sealing, (3) flushing with silt or other solids, (4) flooding with water, (5) cutting off, (6) surrounding with incombustible materials, (7) digging out by stripping from the surface. Most fires are extinguished in their incipiency by direct attack and failure to extinguish by this method is due to late discovery, lack of water, and facilities for fighting, or improper procedure in the initial attack. Should the method first pursued be unsuccessful, careful consideration should be given in determining next the method to be adopted; then the work should be carried on as rapidly as possible and under the supervision f the most competent persons. Materials and supplies should be fur-

Jan 9, 1921

By William E. Brewster

Dating back some five years ago, various foundries made inquiries as to the probable total carbon content in a given specification and grade of pig iron. Up to that time we had no data, and except for a few occasional determinations of total carbon, no attempt had ever been made to set up routine determinations of total carbon. In fact, at that time, a cast analysis was considered sufficient, without examining at further length into possible variations of analysis between ladles of the same cast. In view of the various inquiries as to total carbon, we sampled all piles of all grades of pig iron, making complete analyses. Finding some variation in carbon content, we secured more samples and plotted the carbon content with respect to silicon in each grade of iron except for the higher phosphorus foundry iron, where it was necessary to divide the group into twenty-point phosphorus ranges. This is easily understood, owing to the falling off of carbon content with the increase in phosphorus content, silicon in each case being the same. In addition, these curves clearly demonstrate the lowering of the carbon content as the silicon is increased. In order to insure accuracy and reliable determinations the following method of sampling and analysis was employed: Two pigs selected from each end of the car, each car containing iron from one 50-ton ladle, are drilled with a 5/6-in. drill all the way through from top to bottom in the center of one section of the pig. The drillings are collected and transferred to an 80-mesh sieve; the portion passing through and the portion retained are placed in separate envelopes and labeled accordingly. The amount of sample in each envelope is weighed to obtain the proportionate amount of coarse and fine drillings, then a 1/2 factor weight of sample (1.3636 grams) made up of proportionate

Jan 1, 1936

By William E. Brewster

Dating back some five years ago, various foundries made inquiries as to the probable total carbon content in a given specification and grade of pig iron. Up to that time we had no data, and except for a few occasional determinations of total carbon, no attempt had ever been made to set up routine determinations of total carbon. In fact, at that time, a cast analysis was considered sufficient, without examining at further length into possible variations of analysis between ladles of the same cast. In view of the various inquiries as to total carbon, we sampled all piles of all grades of pig iron, making complete analyses. Finding some variation in carbon content, we secured more samples and plotted the carbon content with respect to silicon in each grade of iron except for the higher phosphorus foundry iron, where it was necessary to divide the group into twenty-point phosphorus ranges. This is easily understood, owing to the falling off of carbon content with the increase in phosphorus content, silicon in each case being the same. In addition, these curves clearly demonstrate the lowering of the carbon content as the silicon is increased. In order to insure accuracy and reliable determinations the following method of sampling and analysis was employed: Two pigs selected from each end of the car, each car containing iron from one 50-ton ladle, are drilled with a 5/6-in. drill all the way through from top to bottom in the center of one section of the pig. The drillings are collected and transferred to an 80-mesh sieve; the portion passing through and the portion retained are placed in separate envelopes and labeled accordingly. The amount of sample in each envelope is weighed to obtain the proportionate amount of coarse and fine drillings, then a 1/2 factor weight of sample (1.3636 grams) made up of proportionate

Jan 1, 1936

By J. E. Burke, C. S. Barrett

THE fine lines shown in Fig 1 are typical of markings that may be detected after polishing and etching deformed specimens of alpha brass and other alloys. Although they have long been the subject of discussion by metallurgists their nature is still uncertain and the names that have been applied to them, such as deformation lines or strain markings, indicate this uncertainty. In this paper which reports the results of a further investigation of their nature, they will be called strain markings. INTRODUCTION Matthewson and Phillips1 in 1916 concluded that strain markings appeared only after deformations that exceeded 20 pct. They objected to the markings being called slip lines believing this term should be reserved for surface markings produced by plastic deformation. In 1921, Vogel2 described similar striations which appeared after polishing and etching the roughly ground surface of numerous alloys. He reported that the markings were crystallographic in nature, and since they resemble Neumann bands in iron, at least superficially, he assumed them to be mechanical twins. In 1928, Matthewson3 reported work by Phillips which indicated that the lines were more readily produced by impact than by slow deformation and that in many cases the twins inside recrystallized grains were parallel to strain markings in the original deformed grains. This was taken as evidence that the markings coalesce into annealing twins, and hence that they themselves are mechanical twins. Many attempts have been made to [ ] demonstrate directly that the markings are mechanical twins. In 1934, Samans4 described the results of X ray studies of two deformed crystals of alpha brass. Evidence was obtained which could be interpreted to indicate that the strain markings are mechanical twins, and this remains the only direct evidence to this effect. Several other attempts to obtain similar evidence by X ray diffraction have failed5,6,7 although in no case was the original method of Samans employed. An

Jan 1, 1948

By R. B. Tippin, J. S. Browning

The feasibility of multistage heavy liquid cyclone beneficiation of spodumene was successfully demonstrated in this investigation. The indicated recovery for the multistage circuits was mathematically estimated as continuous test runs would be necessary to determine the true influence of a middlings recycle. In the three-stage circuit, both the concentrate analysis and spodumene recovery exceeded 90%. The two-stage circuits were unable to simultaneously yield an acceptable produce with a satisfactory recovery. With the Nation's growing industrial mineral requirements, the U.S. Bureau of Mines has undertaken the task of investigating new mineral dressing techniques and improving the existing concentrating methods of ore beneficiation. One such project is the gravity concentration of minerals using heavy liquid separation (HLS).1-3 Heavy liquid separation is based on the simple principle that a material, whose specific gravity is less than the density of a solution, will float on top of the liquid and a material with a greater specific gravity will sink. Heavy liquid separation techniques were developed in the laboratory over half a century ago but the process has yet to be commercially adopted. In the past, commercial operations have failed because of numerous problems.4 Industrial interest has recently been reactivated because of engineering advances. The number and quality of the heavy liquids suitable for mineral processing has increased while the cost has sharply dropped. New and improved liquid recovery systems5,6 are under consideration with present emphasis on 1) solvent extraction, 2) thermo-evaporation, and 3) water washing. The toxicity of the heavy liquids7 presents a problem, but throughout the chemical and mining industries, many similar hazardous materials are safely handled. A distinct advantage of using heavy liquids is its ability to provide a near perfect separation of fine-sized mineral particles even when the specific gravities are close. Effective separations have been made on minerals down to 200 mesh and with a density

Jan 1, 1968

By Edward Keller

GOLD MOVEMENT ON SURFACE OF AURIFEROUS COPPER WHEN LATTER IS SUBJECTED TO OXIDATION SOME years ago the writer's attention was called to the fact that rolling-mill scales from auriferous copper do not have the gold content proportional to the gold contained in the copper from which they are derived. I So, later, he made a few simple experiments, which are described herewith. In: order to test the gold movement on the changing surface of a copper plate under the influence of oxidation, plates 6 in. by 8 in. by I in. (15.2 cm. by 20.3 cm. by 2.5 cm.) of converter copper, refined, of 99.29 per cent. purity, and leaded copper with a content of 95.65 per cent. copper, were obtained. Ten cuts were made through the thickness of the plates along the longitudinal center and the silver and gold content ascertained in each of the 10 samples in both plates, as shown in the accompanying illustration. The assay results, recorded in Tables 1 and 2, show that the gold distribution is relatively uniform in both plates, while silver has greater variations, especially in the leaded plate. The plates subjected to oxidation were placed in a red-hot muffle for about 2 hr., two small scorifiers being used as supports. Arranged alongside each other, they nearly filled the width of the muffle, and so were practically under equal conditions of heat and draft. The accurate observance of the time was not possible, however, because of other work, but the time of the exposure of each plate in a pair was identical. At the end of each period, each plate was plunged into water and completely freed of scale, which was carefully collected, dried, weighed, and analyzed. Samples of the plates had also been taken of the molten metal and duly analyzed. Table 3 contains the analytical data for the two plates and their several sheets, or layers, of oxide scales. These figures show that in the oxidations of the converter copper the silver is fairly uniform, while

Jan 1, 1919

By Eugene A. Stephenson, Leon J. Pepperberg

The natural gas industry is essentially a byproduct of the oil industry. When first discovered the gas was usually regarded as a nuisance, and even when found immediately associated with oil, or suspected to be so, it was customary to blow it freely into the air, in the hope that gas would shortly be replaced by a flow of oil. The early methods of production,' transportation, and utilization were neither economical nor efficient; the chief value of gas was based on its use as a fuel, with no regard to (1) its effect. upon the oil with which it was associated, (2) its importance as a lifting agent, or (3) to its possibilities for the manufacture of byproducts. The spread of scientific research among major gas and oil companies, manufacturers, and academic groups, has gradually brought recognition of the fact that many of the technical problems bearing on production, transportation and utilization are common to both the gas and the oil industry. A few of the problems that have received serious study, and from which highly gratifying results have been obtained, are: (1) gas measurement, (2) oil well and gas well capacity tests, (3) elimination of field waste, (4) design of pipe lines and compressor stations, (5) extraction of constituents which might interfere with the normal flow of gas through the line, (6) control of reservoir pressure, (7) estimation of reserves of both oil and gas, (8) control of water encroachment, (9) measurement of factors which influence fluid movement through sands, (10) solubility of gases in oils, (11) effect of dissolved gases upon the properties of the solution. These investigations have demonstrated that almost every problem relating to oil production also involves some phase of natural gas engineering. During the past 15 years the use of experimental methods for the discovery and measurement of obscure, influencing factors, which cannot be determined purely by hydrodynamic or thermodynamic analyses, have contributed much towards the progress made in solving the problems of the oil and gas industries. Most of the experimental work on

Jan 1, 1934