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By Bernard Rachlin

In the mineral industry measurement of density or specific gravity of slurries is often necessary or highly desirable. To date the most successful method of measuring the specific gravity of various media is to hand weigh a constant volume sample of the slurry. This method is time-consuming, however, and is intermittent rather than continuous. Most density measuring instruments in use today are variations of three basic systems: air bubble tube systems, radioactive methods, and displacer systems. The high cost of the radioactive cell, combined with the precision electronic measuring that is required, limits the practical utility of this procedure to a small percentage of critical processes. In the air bubble systems clogging of the bubble tubes with solids has rendered this type of measurement completely ineffectual for many applications. Continuous or intermittent purging of the bubble tubes with air or water to prevent tube clogging has been tried but has not been very successful, especially in the heavy media process.

Dec 1, 1956

W. L. Saunders, New York, N. Y. (communication to the Secretary*):—The Laramie tunnel, though a small one, compares very favorably in the speed of driving with the great Alpine tunnels which have the record so far. I think it safe to say that, taking all things into consideration, the record made at Laramie is the best American record, though it still falls short of the long-tunnel records abroad. In discussing tunnel-records it must always be borne in mind that there are conditions peculiar to each individual tunnel job, so that no comparisons are complete, fair and conclusive. At Laramie there is one point which stands out prominently, and which distinguishes this from any of the recently-built Alpine tunnels, and that is that here we have great progress in an American driven tunnel without the use of a carriage for mounting the drills. At the Arlberg and Loetschberg tunnels, the carriage was an essential condition for progress. All the heading-drills were mounted upon a bar which rested upon a small carriage. This carriage was withdrawn after the drilling and run into the heading after the blast without much disturbance of the drills, and with very little adjustment except that required in jacking the horizontal bar across the tunnel. The carriage was so small in its track-area that it required little mucking to run it in to the face; and as the rock-drills used were heavy machines 38 in. in diameter, progress in setting up and drilling was very much accelerated by the use of the carriage. At the Laramie tunnel hammer-drills were used instead of piston-drills, and here we have an important distinction which

Jan 1, 1913

THE LIFE and works of Alexander Agassiz, first president of the Calumet & Hecla Mining Co., were recalled to memory when a monument bearing his statue was unveiled in Agassiz Park, at Calumet, Mich., on Sept. 26, The statue is the work of Paul W. Bartlett, of New York, and was erected by George R. Agassiz, eldest son of Alexander Agassiz. We are indebted to Rodolphe L. Agassiz, now president of the Calumet & Hecla Consolidated, for the accompanying photograph of the statue. The principal address at the unveiling ceremony was delivered by Allen F. Rees, of Houghton, who said, in part: To the world at large Alexander Agassiz was preeminently the man of science. With all his devotion to the industrial life of this district, he found the time to devote to the con-tinuation of his work of scientific research which had been the life work of his fa-ther, Louis Agassiz. Not only did he acquire eminence for his scientific at-tainments and learn-ing, but he was recognized and hon-ored throughout the civilized world for his achievements and accomplishments in the realm of original research. His work in the fields of nat-ural science, in oceanography, in marine zoology, and in other similar lines of research, has added much to our knowledge of the world's mysteries. His life was one of accomplishment also in the industrial world. The union in one life of acknowledged achievement as a scientist and the accomplishment of great results in the prac-tical industrial world is a rare thing, and its possibility has never been exemplified in greater measure than in his life and its results.

Jan 11, 1923

By G. W. White

Over the past several years, the steady progress of gas lift from a mysterious art into a developing science has been traceable through the many fine papers that have appeared in Journal of Petroleum Technology. Consequently, this magazine has rightly become a standard for the serious students of gas lift all over the world. The following discussion is offered in a sincere attempt to accurately present certain topics covered in the subject paper in the light of acknowledged state of the art procedures. INSTALLATION DESIGN The first point to be questioned is the author's installation design, beginning with Eq. 6. The use of 1,200 psi in the spacing equation instead of the 1,275 psi noted as available seems, at first glance, to be a simple arithmetic error. Upon further examination, it appears evident that both this 75 psi plus the 100-psi safety factor must be subtracted from available kickoff pressure because of conditions imposed by the characteristics of the ASC valve (see Fig. B-1). Pressure-charged valve design is incorrectly penalized by spacing the first valve using only 1,100 psi. The use of such a high back-pressure makes it appear that a typical ASC installation would require no more valves than a comparable conventional valve installation. Using a value of 100-psi tree pressure, the well could be valved to 11,000 ft very conservatively with seven pressure-operated valves, but would still require 11 ASC valves. The use of 400-B/D spacing gradient for a 140-B/D rate is not an accepted practice using precharged valves. The author would have done well to note the advantages to be gained by reducing the 500-psi tree pressure, which is clearly explained by Beadle, Harlan and Brown.' In Step 1 of Part III of the continuous flow discussion, the author incorrectly applies the Poettmann and Carpenter curves.2 Item 2 is an incorrect statement. An excellent reference on this point is the paper by Baxen-dell and Thomas.' VALVE MECHANICS The next topic relates to the mechanics of precharged valves. Eq. 2 for the ASC valve can be used to describe the condition of equilibrium, wherein the valve is closed with opening pending. When this equation is used to determine relative values of casing, dome and tubing pressure with conditions approaching the transition value, some strange results are obtained. The following uses the author's symbols and values given on page 689. Fig. B-1 shows the condition that exists at the moment an ASC valve has been uncovered during the unloading process (Condition I). The obvious result is a locked condition. The basis for the curve is shown on the figure which includes 1,000 psig casing pressure to uncover the valve. If injection gas is not bled off the casing until the pressure is decreased by an amount exceeding the stabilizer discharging valve pressure, upward adjustment of the casing pressure is mandatory for the valve to open and unloading operations to continue. In Condition I the dome pressure exceeds the casing pressure by 20 psi, and the tubing pressure required to open the valve is 1,212 psig. This tubing pressure would not exist under the assumed conditions. In Condition I1 the casing pressure is increased to the dome pressure, and the tubing pressure required to open the valve is 1,102 psig. It is apparent that the casing pressure must be increased to a value exceeding the dome pressure before unloading operations could continue. In Condition I11 a maximum casing pressure of 100 psi (stabilizer charging valve set pressure) above the dome pressure is reached, and the tubing pressure required to open the valve is 549 psig. The author's statement after Eq. 5 that "the minimum tubing pressure required to open an ASC valve is equal to the casing pressure at depth less the transition pressure of the valve" is incorrect except for Condition I11 only. Otherwise, the equation is invalid.

Jan 1, 1965

By A. Q. Tool

THE necessity of accurate temperature measurements in the glass-making industries is today being much more widely appreciated than in the past. The introduction of the modern simplified and perfected pyrometric methods in connection with exact regulation of furnace temperatures has caused a marked improvement in the glass product with a quickened rate of production. An example of the processes in which much improvement has been and still can be made is that of annealing or heat-treating the glass. This is one of the most delicate processes in glass manufacture and one that requires a most careful furnace control. The heat treatment is undertaken to decrease the possibility of breakage and, in glass for fine optical instruments, to prevent serious warping of accurately ground and polished surfaces and to make the glass more uniform throughout to the passage of light waves. These objects are accomplished by removing all the harmful stresses that exist in a piece of glass when it has been cooled too quickly or unevenly. Such stresses exist, for example, after it has been pressed, cast, or otherwise worked. Thus the process of annealing consists of heating the glass evenly to the temperature at which it softens just enough to relieve these stresses in a reasonable time and then cooling slowly and uniformly until the glass hardens again. Accordingly, the things that must be investigated and determined in order to anneal glass without loss of time are, the annealing temperature, the time that the glass should be held at this temperature while the stresses relax, and the quickest cooling procedure that will give satisfactory results. After these characteristics of the glass are known the problem is one of pyrometry and temperature control entirely. In cases when it is known that a glass article will be required to withstand some definite type of heat or mechanical shock it is often possible, by a proper heat treatment, to produce such a distribution of the stresses in the glass that it will be enabled to resist these shocks more effectively.

Jan 9, 1919

By Colin C. Harris, Nathaniel Arbiter

Flotation kinetics is the study of the variation in amount of froth overflow product with flotation time, and the quantitative identification of all rate con- trolling variables. With such variables maintained constant, the algebraic relationship between the proportion of mineral floated and flotation time is a flotation rate equation. This contains the constant values of all the rate determining variables implicit in one or more rate constants which must be evaluated from experimental data. The form or forms of the rate equation can either be deduced from assumptions or facts established about the mechanism of the process, or, more commonly, determined empirically or by analogy with similar rate process. (See pages 215 to 226 and 221 to 227.) The earliest contributions on flotation kinetics came in the mid- ~hirties,3,27,31 with interest increasing in recent years. The broad goal of these studies is the reduction of the total variability of a flotation system to equations among the individual variables, or among a lesser number of dimensionless groups.43 Although the goal is at present far from realization, its attainment will yield many practical advantages. The quantitative under- standing of the process should lead to improvements both in metallurgical results and flotation cell design. It should lead also to reliable methods for scaling-up* of laboratory and pilot plant results to full size operation without the need for expensive and time-consuming mill tests on commercial machines. Finally, this type of quantitative information will assist the automation of flotation cells and circuits as well as control by computers. Replacing present methods of control based on post-mortem assays and trial and error manipulation of reagents and cell variables by control through exact process analysis should yield higher levels of grade and recovery through reduction of the large variability of present-day results. CHEMICAL ENGINEERING ANALOGIES: Industrial flotation always involves flow of pulp through a series of stirred tanks. It thus bears formal analogy to many chemical engineering processes, the kinetics of which in flow systems has been studied for many de- cades.38,39,73,83 It will be useful to review these studies before considering flotation kinetics. Batch and continuous treatment are classified in Fig. 1. Batch operation in the true sense is unknown in flotation where concentrate is always removed

Jan 1, 1962

W. 0. HOTCHKISS,* Madison, Wis.-When we began to do geological field work in the Lake Superior region, we found a correlation in existence, and, as youngsters, accepted all that as settled. Both Mr. Allen and I, since that time, have seen a great many things that were not apparent nor visible to Van Hise, and those who worked with him; we realize now that the correlation was not final and that much remains to be determined concerning geology of the Lake Superior region. My attitude on this matter is that we should not publish an amended correlation as a final thing. We should avoid, in every way possible, foreclosing the minds of those who follow us in working in the geology of this region. As a matter of fact, no correlation can be final at present, because facts and data are accumulating so rapidly that every classification must be immediately modified to fit further observation. Consequently, my attitude in this matter would be, instead of saying that the iron formations of the Lake Superior region are all Middle Huronian, to say that there may be three Huronians-or four or five- we do not know. I believe it is better policy to hold to our present correlation. I do not believe there is any economic benefit to the mining man or the geologist working on problems relating to explorations for iron ore, that cannot be just as well solved by maintaining our present correlation, with a. wholesome idea of our lack of knowledge and the necessity for further detailed work. Then, if any new horizons are discovered in any particular range, the minds of the investigators will not be foreclosed because some one has said that all the iron formation is in the Middle so that there is no use looking elsewhere for it. There is use looking elsewhere, in many cases, as the ore deposits become exhausted.

Jan 1, 1920

By J. W. Littleford

The Roan Antelope Copper Mines Ltd. are situated in the north central part of Northern Rhodesia, at an altitude of 4000 ft. and 13" south of the Equator. The town site (Luanshya) is well situated and enjoys among other things a really temperate climate for 10 months of the year. The two spring and summer months, October and November, while hot and humid, do not bring any great discomforts as compared with many other mining camps. Strictly modern brick homes, with electric lights, purified water, telephone and water-borne sewage, add to the comfort of the employees. A rainfall of approximately 60 in. per year furnishes ample water for both industrial and domestic purposes. The rainy season generally begins in October and lasts through until March. As much as 3 to 4 in. is recorded in 24 hr., but this offers no difficulties because the runoff is very rapid. The property is connected by a 24-mile branch line from Ndola with the main line of the Beira-Mashonaland and Rhodesia Railways Ltd. Practically all supplies from overseas are transported over this line from Beira, 1743 miles distant on the east coast in Portuguese East Africa. The mine output also leaves Africa from this port. Passenger service is principally via Cape Town or Durban, a distance of about 2100 miles to either port. The Imperial Airways maintain a service from Cape Town to Croydon, taking 9 days for the trip. Connections can be made with this service at Broken Hill, 150 miles south of Luanshya, by either rail or automobile. Thus, after several days of travel through virgin bush, a visitor arrives at a typically modern town site in the heart of Africa. Every development in mining, milling and smelting practice is used to advantage. Plan of Mill The practice in the three principal phases of the production of copper from the ores of this company have been published from time to time. Milling practice, however, is continually changing and what may be

Jan 1, 1935

By J. L. Sepulveda, R. F. Yap, R. Jauregui

INTRODUCTION The Third Theory of Comminution, oftentimes called the Bond Theory, was first published by Fred C. Bond in 1952. Since then, it has been widely used in the milling industry to size crushing and grinding equipment as well as to predict and evaluate their performance. Although two other comminution theories were advanced almost a century earlier, one by Rittinger, 1867, and the other by Kick, 1885, their use was limited because they did not agree with actual commercial comminution systems (Bond, 1961). According to Bond's Third Theory, the work input is proportional to the new crack tip length produced in particle breakage, and equals the work represented by the product minus that represented by the feed. For particles of similar shape, the crack tip length is equivalent to the square root of one-half the surface area, and the new crack length is proportional to [(1/vT - vF)]; where P and F are particles diameter of product and feed, respectively. For practical calculations, the particle diameter can be expressed in terms of the 80% passing sizes, P and F, respectively. Therefore, the work input is given by, [10 _ 10', W = Wi [7P_7F(1)] Where W = the energy input to the mill, (kwh/t) Wi = Work Index, (kwh/t) P = square sieve opening which 80% of the product passes, (microns) F = square sieve opening which 80% of the feed passes, (microns) Equation (1) is the mathematical statement of the Third Theory, or the Bond equation. Numerically, the work index is the energy required in kwh/t to reduce a given material from theoretically infinite feed size to 80% passing 100 microns. The work index of a particular material is determined in the laboratory by conducting the standard Bond grindability test. Bond developed separate tests for the rod mill and the ball mill. The simplified test method described in this paper, which is used at Anaconda Research Center to approximate the work index, is an alternative procedure to the ball mill

Jan 1, 1982

By Eugene R. Rice

(Canal Zone Meeting, November, 1910.) THERE are many methods for determining the meridian, but all of those in common use involve at least two separate observations, one for latitude and one for azimuth. Such observations made upon a south star at any hour are open to the objection of possible inaccuracy due to ignorance of the absolute refraction, and also to slow change in the altitude of the star when near the meridian. The method of observing a circumpolar star at elongation, besides requiring a separate observation for latitude, is open to the serious objection that clouds may obscure the star at the critical moment. Moreover, a tedious wait for the star to come to elongation is sometimes necessary. Many of us can recall long, cold, weary vigils, waiting for Polaris to reach elongation. For observing a circumpolar star at any hour, not only the latitude, but also the true time, must be known. This it is practically impossible to obtain, except in regions reached by the telegraph, and usually then one has to know the longitude also, in order to reduce "standard time" to "local time." The results obtained by this method, when the star is at culmination, are not very good, unless the true local time is absolutely known. The methods of obtaining the meridian from the sun, by means of a solar attachment, or by direct observation, while good, are not absolute, by reason of refraction, change in declination of the sun, and small change in vertical angle, when the sun is near the meridian. For these two methods, latitude, time, and approximate longitude have to be known. In the method here described, only one observation is needed, and from it azimuth, latitude, and sidereal time are computed. In other words, one can observe a circumpolar star-Polaris

Nov 1, 1910

By Adrien Berton

FOR nearly a century, the Corocoro deposit has been renowned among geologists from the fact that it shares with the Lake Superior deposits of the United States the distinction of being the only important copper districts where native copper is worked commercially. The Corocoro district, named after the city of Corocoro, the capital of the Province of Pacajes (Department of La Paz, Bolivia) is situated towards the western edge of the Bolivian high plateau, at an altitude of a little over 13,000 ft. The most interesting part of the district is that immediately surrounding the city of Corocoro, at a distance, by railway, of 65 miles from La Paz and 210 miles to the Chilean port of Arica on the Pacific Coast. The climate of the region is that of the semi-desert, dry and relatively cold, with big differences of temperature between day and night. The rainy season begins in December and ends in March. The cupriferous lodes of Corocoro have not attracted as much interest as the silver mines of Potosi but they have been known for a long time. In the precolonial period the Indians were using the charquis, or natural native copper sheets, to make small brass objects, and the beautiful pale green brochantite of the outcrops as a source of green pigments. During the colonial period, the oxidized ores of the outcrops were worked for copper, which was used by the mint at Potosi for making currency. The native copper ores were neglected because the Spanish miners were at a loss how to concentrate and smelt them. About 1830, work by rudimentary processes, which were improved little by little, was begun on the native copper ores. The total production of native copper in the following hundred years amounted to 100,000 tons. This native copper, which was remarkably pure, was much appreciated on the European markets before the introduction of electrolytic copper. It was useful for making special ornamental brass or bronze and the granular concentrates of native copper, called barrilla, containing 80 to 85 per cent copper were suitable for making copper sulfate by direct oxidation and subsequent leaching with sulfuric acid.

Jan 1, 1936

By G. W. Jones

THIS paper describes experiments in which eight test samples of gelatin dynamite were fired in three different types of apparatus and the quantity and composition of the gaseous products of detonation determined. The special dynamites were so prepared that the oxygen balance of the samples varied from -35.0 to +6.0 g. per 100 g. of explosive, including the wrapper. By means of this graded series of explosives, the relation between oxygen balance and gaseous products of detonation could be studied explicitly. The effect of varying oxygen balance on explosive strength has-been discussed in another paper.1 The apparatus employed in the work described in the present paper included (1) the Bichel gage, a steel bomb of 15-1 volume; (2) the Crawshaw-Jones confined detonation apparatus, a steel cannon from which the explosive is fired into a pipe of 904 volume; and (3) the Hercules tank, an apparatus in which the explosive is confined in a quartz block which is placed in a steel tank of about 4500-1. volume. A full description of the apparatus is given later. VARIABLES AFFECTING COMPOSITION OF DETONATION PRODUCTS The character of the detonation products of commercial explosives is governed in part by the same factors that affect the combustion products from explosive mixtures of air with gases or vapors. In either case, combustible materials-namely, carbon, hydrogen, and sometimes sulfur-are present and combined variously. In an exploding gas mixture the combustibles are oxidized by oxygen in the admixed air, whereas with explosives the necessary oxygen is provided by oxygen-carrying materials in the explosive ingredients.

Jan 1, 1928

By Sultan Amerie

PERSIA looms up more prominently each year as one of the richest oilfields in the world. The actual production in the south and the possibilities in both the north and the south are very great. The output in the south, where the Anglo-Persian Oil Co. operates a wide concession, is steadily increasing, the returns for the fiscal year 1922-23 being 2,957,028 tons. The estimated production for. 1923-24 is 3,775,000 tons. The figures for the past few years have been as follows: 1918-19 1,106,415 tons 1920-21 1,743,557 tons 1919-20 1,385,301 tons 1921-22 2,327,221 tons According to the company's last annual report, the production from the -Persian fields operated by its subsidiaries has been well maintained and is now being increased to deal with the expanding off-take of the company's refineries at Abadan, Persia, and Dandarcy, Wales. Test drilling in an entirely different area in Persia indicates the existence of a new oilfield, which it is intended for the time being to hold as a reserve.

Jan 3, 1924

By James Boyd

It is obvious that mining has been influenced to a high degree by political and economic events, many of which are of such a nature that the mining industry has relatively little influence in shaping them. I cannot present too optimistic a picture for the immediate future, although I feel that from the long-range standpoint one need not be pessimistic about the future of the mining industry. The population of the United States is continuing to increase and with it has come an expanded consumption of metals on a per capita basis. With this expansion there has and will continue to come the demand for more goods and in- creased products from our mines and our fabricating plants. World War

Jan 5, 1950

By Jacques B. Wertz

Even with the best geological maps, there is a constant need for further information and a constant demand for new clues, particularly in exploration work. New ideas and new thoughts are a necessity for progress. In the structural study of an area, be it in Arizona, Africa, or British Columbia, the basic fracture pattern has to be determined first. There is, however, no assurance that the trends shown on the map are really meaningful because they often are secondary in nature, having occurred as a consequence of an intrusion, of doming, or of gravity faulting. Thus, such trends often are a weak basis for assuming the presence of ancient and important zones of fractures that could constitute useful guides to mineral exploration.

Jan 6, 1969

By R. C. Mahon

THE importance of ground water control in glacial drift overlying mines is widely recognized. Adequate handling of the problem results in considerable saving in overall pumping costs, as the cost of pumping the larger quantity of water under low heads from surface wells is more than offset by the decrease in the quantity of water to be pumped from the mine under high heads. Eliminating or partly reducing seepage of water through the ledge reduces moisture content of the ore, a factor especially important in iron ore mines, where a reduction of 1 pct in moisture effects a very material saving. An important though indeterminate saving is also brought about by the elimination of water in the working places underground. The Homer and Wauseca mines of Hanna Coal & Iron Co. at Iron River, Mich., cover 480 acres. When these mines were started it was possible to operate on only one 40-acre tract, as the depth of water over the remainder of the property was too great to permit operation. Although the average depth of the ground water over the area being mined at that time was less than 50 ft it was necessary to pump 1200 gpm from the mine, the greater part from a depth of 750 ft. The slate footwall and graywacke hanging wall are almost impervious, and it was apparent that seepage into the mine was mainly through the iron formation in which the orebodies were located. Analysis of the water in the iron formation showed it to be of the same character as that in the glacial drift, while the water in both walls was heavily mineralized, also indicating that the water passed much more freely through the iron formation. The first attempt to take off the water above the ledge was by means of drainage drifts driven 15 to 20 ft below the ledge, Fig. 1. Various schemes were used to get the water into these drifts: 1—Holes 15 to 20 ft long were drilled from the back of the drifts to the ledge, but these were difficult to drill and blocked easily. 2—Sections of the drifts were blasted down. This gave a large flow for a time but eventually almost total blockup occurred. 3—Raises 4x4 ft were driven above the drifts to within 8 ft of the

Jan 1, 1955

The housing of labor and sanitation at mines in India are difficult problems to solve because-no more than two or three castes will accept the same conditions, and conditions suitable to one coal-field are not applicable to other fields. It is also necessary to consider the financial standing of the different companies. The European companies, which pay 30 per cent. and more dividends, can erect more suitable houses than the Indian companies, which are just able to keep their heads above water. The Santhal will not live in a bucca-roofed house as a permanent dwelling, and both the Santhal and Koras have an aversion to living in a line of attached huts. They have forsaken a whole, line of houses in one of which a case of sickness or death has occurred, and those houses were afterward considered unfit by all other classes of natives. The Santhals, Koras, and Douri castes will not take drinking water from a stand pipe; wells must be furnished. When well water is not available, these people will take water from the nearest pool or tank regardless of whether or not the water is stagnant. The well tops should not he completely enclosed, nor should there be a drain around the top. The ground should slope away from the well. In the Girieih coal fields, the miners have a great objection to pucca floors; they prefer earth which is lapped, easily cleaned, and renewed. As it is customary for the miner to build his own house, the company supplying the roofing material, he takes a special interest in it, keeps it in order, and hesitates to leave it. Each house is surrounded by its own bit of land, which the inmate cultivates.

Jan 12, 1918

By I. Ionel Gardescu

During the latter part of 1930 an agreement was reached among operators in Rumania to curtail the production of oil to about 100,000 bbl. per day. This agreement lasted only a few months and 1931 shows a new peak in production with an average yield of 136,900 bbl. per day as against an average of 116,600 bbl. per day for 1930. The total production for 1931 was 49,210,000 bbl.; an increase of 18.4 per cent over the previous year's production. It is interesting to compare the percentage production of the major companies to the potential production figures determined by the Government in September, 1930 (Table l), on the basis of which the proposed curtailment was to have been made. The three companies listed first in this table show an increase in average production for 1931 over their estimated potential production rating. This increase might be attributed at least in part to the recent development of the Boldesti field, which is controlled by these companies and of which the production at present is nearly 10 per cent of the total oil output for Rumania. Among the other fields, Moreni still holds first place with an output of 33.6 per cent, followed by Gura-Ocnitzei with 29.3 per cent. In both these fields the main source of oil is from the deeper Meotic sands. Other

Jan 1, 1932

By W. Rostoker

The process of diffusion alloying of mixed powders offers attractive possibilities both commercially and experimentally. It avoids the fabrication difficulties arising from high alloy contents. Indeed, the process is facilitated by larger alloy additions. The direct formation of the part or test piece and the opportunlity to perform machining operations under more favorable conditions are of no small importance. However, it is necessary to make only brief mention of the interesting features. As yet there have been few attempts to study this process in detail and to carry it to completion, if such is possible. It was intended not only to measure the intermediate and optimum magnetic properties of sintered alloys but to use magnetic testing itself as a means of following the progress of alloying under various condi-tions. Having established that alloys could be successfully synthesized by this tech. nique, the opportunity was taken to study the magnetic properties of several alloys of iron and silicon which had hitherto been too difficult to prepare in suitable test piece form. While avoiding some of the difficulties inherent in the fabrication of alloys by orthodox methods, the diffusion alloying process introduces a few of its own. The first of these is the evaluation of the approach to homogenization. In recent years some notable contributions have been made to this question, but considerable uncertainty remains in its definition and evaluation. This work has concerned itself with further study of this problem and it is hoped that more light has been shed on it. The second of these difficulties arises from the presence of porosity. It is inevitable that in the consolidation of a loose bulk of powder, there should remain some voids unless extremely high pressures are repeatedly applied. It was therefore of importance to investigate their effect on magnetic properties. Recently this effect has been studied and certain predictions made of its behavior. It is believed that the experimental results presented here provide a sound substantiation of the theoretical treatment. The attempt has been made to synthesize five alloys of the iron-silicon system and three each of the iron-nickel and iron-cobalt systems. A series of experiments was also conducted on some of these alloys to test their susceptibility to heat treatment. Some unfortunate experiences have provided opportunity to report data on the deleterious effects of nitrogen on magnetic properties when present as a a in protective atmospheres. MateRIALS, PREPARATION OF SAMPLES and Testing The purest materials available were em. ployed for this work. A specially purified,

Jan 1, 1949

By Y. C. Liu, G. A. Alers

The effect of rolling reduction on the textures of Cu-A1 alloys has been investigated both by pole figure and by modulus methods. In alloys which exhibit complete copper or brass types of rolling texture, the rolling reduction has little effect on the texture except to increase the degree of preferred orientation. In alloys which exhibit a transition texture, however, increased rolling reduction increases the amount of brass-type texture at the expense of the copper-type texture. The present experimental results show that there is no one-to-one correspondence between the SFE and the rolling texture of fcc metals. Additional data taken from the literature for fcc metals also support this conclusion. On the other hand, the present and previous experimental results are shown to be in good agreement with the suggestion that the texture transition occurs at a critical value for the separation distance between two partial dislocations—a consequence of the "dislocation interaction" hypothesis for texture. formation. This critical separation occurs when the parameter .r/ub is 3.75 x 10'3. From this, a value for the SFE of 39 ergs per sq cm may be deduced for a Cu-2.85 at. pct A1 alloy. ThE correlation between the rolling texture of fcc metals and the stacking fault energy, SFE, was one of the first attempts to relate atomistic properties with the type of rolling texture.' This correlation gives a qualitative explanation for the experimental observation that the addition of alloying elements, which generally lower the SFE, changes the copper-type texture to a brass-type texture. The simplicity of this correlation had led to its general acceptance and even its quantitative use.' However, it is only a correlation and is largely based on descriptive features of pole figures, and on the poorly known SFE values in dilute alloys. Quantitative verification of this phenomenologi-cal correlation is, in fact, completely lacking. One purpose of the present study is to test this correlation. Another atomistic description for the formation of rolling texture is the "dislocation interaction" hypothesis of texture formation.3 In this hypothesis, the factor controlling the type of rolling texture depends on whether or not the separation distance between two partial dislocations exceeds a critical value. Materials having a separation of less than the critical value are supposed to exhibit a copper-type texture while those with a separation above the critical value are supposed to have a brass-type texture. At the critical value, it is expected that the material should show equal amounts of copper- arid brass-type orientations in their textures, i.e., a 50 pct transition texture. The SFE appears in this hypothesis as only one of several factors which determine the separation distance between partial dislocations. It is possible to test the validity of these two concepts by studying the rolling texture as a function of rolling reduction. Since the SFE per se is an intrinsic property of the metal, it should not, by definition, be influenced by local irregularities, such as variable stress conditions. Thus, no change in texture-type is expected to occur with changes in rolling reduction. On the other hand, according to the "dislocation interaction" hypothesis, any factor that effectively influences the separation distance of partial dislocations would be expected to change the rolling texture. Since the separation distance between partial dislocations is known to depend upon local stresses,4-6 it is anticipated that there would be an effect of the degree of reduction on the texture-type. Also, since applied stresses are more likely to increase, rather than to decrease, the separation between partials,4'5 the overall effect would be to increase the amount of material in the brass-type orientations as rolling reduction is increased. Furthermore, this reduction dependence would be most prominent in alloys exhibiting the transition texture since the distance between partials in those alloys is thought to be close to the critical value. Experimental data in the literature is insufficient to distinguish between these two alternatives. Haessner studied the effect of rolling reduction on textures in a series of Ni-Co alloys by means of the X-ray intensity-ratio technique,' and found that while one texture parameter indicated no reduction dependence the other indicated a slight dependence of the rolling texture on reduction in the range of 96 to 99 pct. As has been noticed previously, the intensity-ratio technique is a convenient but controversial method7 because there is no a priori reason to suggest which intensity-ratio would describe the texture most meaningfully. A more quantitative method of describing textures is found in terms of the orientation dependence of Young's modulus. Here, the type of modulus aniso-tropy associated with the copper-type texture is sufficiently different from that observed for the brass-type texture to allow the two types to be easily distinguishable and a quantitative measure of the amount of each can be deduced from the numerical results. This ability to provide quantitative data is particularly valuable when the two textures occur simultaneously in one alloy as is the case for the transition textures. In this paper the modulus method, supplemented by pole figure data, is used to look for an effect of roll: ing reduction the texture. Also by combining the texture measurements with recent determinations of the SFE in Cu-A1 alloys'0'" it should be possible to test for a relationship between the SFE and textures.

Jan 1, 1970