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By T. R. Scott

The acid pressure leaching of zinc-lead flotation concentrates from the McArthur River deposit, Northern Territory, Australia, has been studied in a three-stage, continuous, co-current system, using titanium reactors of 6 gal capacity. The starting pulp contained 2.7 lb solids per gal of synthetic spent electrolyte and the final liquors contained 120-125 gpl Zn. Parameters investigated included temperature (95-120°C), oxygen pressure (30-100 psi), acid addition (80-130% of theoretical), and leaching time (35-65 min per stage). Technical factors studied included mixing and pumping of feed, agitation, settling and washing and control mechanisms. The chemistry of liquor impurities, of scale formation in autoclaves and of lead jarosites in residues was studied in some detail. Results indicated that 90-93% zinc recovery could be obtained with a "low- acid" process, using 113°C and 70 psig with oxygen as the favored operating conditions. Residues contained 16-18% elemental sulphur and 15% lead, together with unreacted pyrite and gangue minerals. Pelletizing of residues was impracticable, and alternative suggestions for the recovery of lead, sulphur and silver are discussed. Preliminary estimates for plant and operating costs are given and enable some comparison to be made with conventional procedures.

Jan 1, 1973

By J. H. Nead

OBJECT THE experiments herein described were undertaken with a view to investigating thoroughly the influence of carbon on the tensile and impact physical properties of carbon steel. The original comprehensive plan included investigation of a series of steels with varying carbon contents over a wide range of heat treatments. These were to be studied as to their static tensile qualities, and also their resistance to shock as measured by the Charpy impact bending test. A thorough metallographic examination was likewise included in the schedule. The Charpy tests and the metallographic examination have not been completed to date, and are accordingly withheld for another report. All heat treatments, however, have been made, and the static tensile tests have been completed. A description of the procedure of the experiment and the results thus far obtained are therefore reported herein. CONCLUSIONS No attempt is made to draw general conclusions from these experiments, but the curves and the data are submitted as being of general importance and wide applicability.

Jan 12, 1915

By M. J. Sheriff, D. H. Smith, W. Macdonald

The paper outlines the basic procedure used in electrical system planning and design. Consideration is given to the use of applicable codes and standards, development and use of a system One Line Diagram, power availability, load requirements and power factor. Also discussed are the factors influencing the selection of power supply and distribution arrangement, voltage levels, system grounding, distribution and utilization equipment such as switchgear, transformers, motor control, cable systems, motors. Short circuit calculation methods and system protection are discussed.

Jan 1, 1978

By Thomas Kesler

THE Cartersville mining district, 35 miles northwest of Atlanta, Ga., has been of varying but continuous importance in the southern mineral industry during the past century. Noted chiefly for its production of brown iron ore, manganese oxide ores, barite, sienna, and magnesian limestone, the district and its environs have produced brick and tile clays, slate, gold, bauxite, and graphitic schist. Minor deposits of serpentine, sericite schist, copper ore, and red iron oxide have been prospected. The obvious deposits of brown iron ore, together with some associated specular hematite, were mined out years ago, although a little ore was left in the workings. Moderately steady production of sienna reached a peak about 1930, then declined rapidly. Manganese mining passed through a relatively active period from the World War to 1931, but has subsided to a small but rather constant output for the Birmingham market. How-ever, the White Manganese Corporation has prepared for possible increased production by constructing a new washer capable of handling about 300 tons of ore per day. Principal activity in the district proper has centered for some years in the production of barite and magne-sian limestone.

Jan 1, 1940

By L. C. Reese

The ultimate resistance against a rigid cylinder which is moved laterally in a cohesionless soil is a function of the geometry of the cylinder and the properties of the soil. An approximate method is developed for computing this resistance and is tested against results of laboratory experiments. Satisfactory agreement between the method and experiment was obtained. Not only was the ultimate resistance against the cylinder measured, but measurements were made of the shape of the rupture surfaces. These measurements should allow the development of a more rigorous computation procedure. INTRODUCTION A critical aspect in the design of offshore drilling platforms is assuring the stability of the platform during a hurricane. The large horizontal loads from waves and wind make a severe loading condition. Piles are generally employed as the foundation since they can be effective in resisting both horizontal and vertical loads. Spuds are sometimes used with a mat foundation, where the spuds are designed principally to resist horizontal loads and the mat designed principally to resist vertical loads. The research reported in this paper is related to one aspect of the problem of laterally loaded piles or spuds in sand. The complete solution to the problem of the laterally loaded pile in sand would require the prediction of soil resistance against the pile as a function of pile deflection; only the ultimate resistance against short piles is considered in this paper. A considerable amount of additional research will be necessary in order to obtain a complete solution to the problem of the laterally loaded pile in sand; however, the work reported here should be useful as a guide in the performance of some of the additional research. ULTIMATE LATERAL RESISTANCE AGAINST A LONG FALL IN SAND To aid in the understanding of the theory which is developed for a cylinder, the theory for earth pressure against a wall is reviewed. In Fig. l(a), a long wall of height H is shown embedded in soil. Soil resistance will develop as the wall is deflected, and the soil resistance will increase with deflection until some limiting value is reached. In this discussion, and those following, it is assumed that all points on the wall deflect equal amounts. A possible shape of the real curve which relates soil resistance to deflection is shown by the dashed line in Fig. l(b); however, as a means of simplifying the discussion, an idealized curve (shown by the unbroken lines) is drawn. If such a wall as this were furnishing the horizontal support for an offshore structure, the dashed curve in Fig. 1 would be the information needed in performing a foundation analysis, with the idealized curve possibly being an acceptable substitute. For the idealized curve, the soil resistance is linear with deflection for the early portion of the curve such that

By C. E. Jr. Reistle

ALL crude oils become more viscous when chilled, but the only oils that congeal and precipitate paraffin to such an extent as actually to cause production troubles are those that contain an appreciable amount of wax. In handling these oils of high wax content, three distinct problems may be encountered before the oil reaches the refinery. The first problem is the precipitation and accumulation of paraffin in the well, either in the oil string or on the face and in the pores of the sand. The second problem is the accumulation of paraffin and the congealing of oil in the transportation lines. The third problem is the precipitation of paraffin and the formation of tank bottoms.

Jan 1, 1927

By W. J. Taylor, H. J. Mutz, A. F. Brock

THE International Kickel Co. of Canada Ltd. operates five underground mines and an open pit. Four of the mines, the Frood-Stobie, Creighton, Murray, and Garson, are on the south range of the Sudbury Basin, map above, within a radius of 10 miles of the city of Sudbury, Ontario. The fifth mine, the Levack, is on the north range of the Sudbury Basin, 30 miles to the northwest of the city. The open pit is operating on surface ores of the Frood-Stobie orebody. Two pits were opened at the Frood-Stobie mine; the Frood section was started in 1938 and the Stobie section in 1942. To meet the heavy demand for nickel during World War 11, open-pit production was accelerated until it constituted over 40 pct of Inco's total tonnage. As a consequence open-pit ore was depleted considerably alhead of schedule; the Stobie pit was completed in the summer of 1951, and it is expected that mining at the Frood pit will be completed in 1953. The major program launched 10 years ago to develop additional underground production as a replacement of open-pit tonnage thus had to be greatly speeded up. This conversion to all-underground mining will be completed within the next two years, and the underground mines will then have an annual hoisting capacity of 13,000,000 tons. One of the new mines in the underground expansion program, the Murray, was brought into production in 1950. Ore production from the new Stobie section of the Frood-Stobie mine was commenced on a limited scale in 1951 and will be increased as the program progresses. Delivery of ore to the new Creighton mill was started in the summer of 1951 from the caving project launched at Creighton mine. When mining was started in the Sudbury district 65 years ago the ore deposits were opened on a small scale and mining methods conformed to a general pattern of small open cast pits, followed by open stopes as mining was extended below the pits. The open stoping methods used were heading-and-bench and shrinkage. In certain cases a type of cut-and-fill mining was used with drywall tramways and dry-wall chutes in the fill. As the mines were deepened,

Jan 1, 1954

By H. C. Howard

Reaction of oxygen and bituminous coal starts as soon as the coal bed is exposed to air and, with some coals, proceeds with significant velocity even at normal temperatures and at normal oxygen partial pressures of one-fifth of an atmosphere. At higher temperatures, the reaction is greatly accelerated and ultimately a condition is reached where the process is very rapid and we then speak of combustion. It is the purpose of the present paper to discuss the reactions of oxygen and coal at temperatures below those of active combustion. It is these low temperature oxidation reactions which are responsible for heating in storage and for marked changes in agglutinating proper-ties. These reactions may also be employed for the preparation of organic acids, which are of direct interest to the chemical industry. For convenience in discussion, the low temperature reactions of oxygen and bituminous coal can be roughly divided into three stages though there is, of course, overlapping. Stage I is a surface oxidation stage, characterized by the addition of oxygen, with the formation of oxygen containing groups some of which have acidic properties. Carbon dioxide, carbon monoxide and water may be formed con-comitantly and are always liberated at higher temperatures, and in cases where the oxidation is prolonged. Superficially, the coal is little affected by this primary stage of oxidation and usually only minor changes in ultimate composition result. There may be definite changes in coking and coking properties, and heat of combustion susceptibility to further oxidation. The presence of acidic groups can be demonstrated by specific reactions. These groups may show cation exchange properties like the mineral zeolites. The formation of oxalic acid has been reported. If the oxidation is continued, a large fraction of the organic material of the coal is converted ultimately into alkali soluble, acid insoluble products, which have been given the name "regenerated humic acids" and which are the characteristic products of Stage 2. These humic acids, in the solid stage, do not differ greatly in appearance from the original coal, but show large differences in chemical composition and chemical and physical properties. Along with the humic acids, carbon dioxide and some of the water soluble types of Stage 3, are also formed. If the oxidation is carried still further, the humic acids may be degraded completely to the simpler, lower molecular weight acids of Stage 3 which are characterized by solubility in acid as well as in alkaline media, and by their orange, yellow or white colors. Additional carbon dioxide is formed in the transformation from Stage 2 to Stage 3 and, for a number of American coals, a maximum yield of the water soluble types of acids is reached when about 50 pct of the carbon of the coal is converted to carbon dioxide. Primary Oxidation The initial step in the reaction of gaseous oxygen on coal, like that on carbon,

Jan 1, 1949

By Sherwin Kelly

IN presenting this brief historical perspective, it is not my purpose to address myself to the geophysicists, to most of whom the story is already well known. My objective is to draw the attention of those who hold the belief that geophysics is something new, typically twentieth century, to the fact that fundamentally, whether it was known by the name of geo-physics or not, the science is an ancient and an honorable one. It began many centuries ago, and our modern civilization and its commerce owe a great debt to its founders, who today are likely to he overlooked and their names forgotten. The word "geophysics" means the physics of the earth, and is descriptive of a science that in many ways bears the same relationship to geology that astrophysics does to astronomy. When dealing with dis-tant stars or deeply buried rocks, the experimenter cannot reach them to obtain samples, which can be taken to his laboratory for study. He therefore exhibits the resourcefulness of Mahomet in the mountain episode, and makes the terrestrial globe or the cosmic universe his labora-tory, studying the effects of distant bodies on certain "fields of force"" which come to him across interstellar space, or through the rocks that make our earth. The application of these techniques of the physics laboratory to the study of the stars is the science of astrophysics, and to the investigation of the earth is geophysics. Yet the origin of the most valuable contribution to the world's trade and commerce ever made by geophysics remains lost in deep obscurity. Unknown even is the country wherein lived the unsung genius who invented the first geophysical instrument, the mariner's compass! Worse yet, it is not certain whether this invaluable guide of man had its begin-nings in Europe or in Asia. A Chinese legend tells of the Emperor Hwang-ti, who attacked his enemy Tchi-yeou on the plains of Tchou-lou in the year 2634 B.C., whereupon the latter magically raised such a fog that the Emperor could not pursue the retreating troops. Not to be outdone, the mighty ruler constructed a chariot that indicated the cardi-

Jan 1, 1938

ADVANTAGES OF LIFE MEMBERSHIP The Institute calls the attention of members to the following advantages of obtaining life membership: 1. One payment avoids the trouble of future payments. 2. The interest on $150 is less than the annual dues. 3. Provision is thus made early in life for the less productive years. 4. In case of in increase of clues at any time in the future life members are exempt from increased payments. Excerpt from, By-Laws. Article III. Section 3 Any Member or Associate not in arrears may become, by the payment of one hundred and fifty dollars at one time, a Life Member or Life Associate, and shall not be liable thereafter to pay annual dues. The money thus received shall be invested and only the income thereof used for current expenses of the Institute.

Jan 1, 1916

1. Healthy and active Local Section organizations are vital factors in promoting the vigor and growth of the Institute. 2. Activity on the part of Local Sections should be recognized and stimulated by appropriation of funds from the Institute's treasury; and these appropriations should be as large as is consistent with the relative needs for other activities. 3. As between different Sections, the amount of such appropriations should be based primarily on the extent of activities as reflected in the number and character of meetings held and the attendance of the members at such meetings. 4. In making a request for funds for any year, the officers of a Local Section should submit a report on the printed form approved by the Directors at their meeting on November 19, 1937. 5. A standing Committee on Local See-

Jan 1, 1943

1. Healthy and active Local Section organizations are vital factors in promoting the vigor and growth of the Institute. 2. Activity on the part of Local Sections should be recognized and stimulated by appropriation of funds from the Insti¬tute's treasury; and these appropriations should be as large as is consistent with the relative needs for other activities. 3. As between different Sections, the amount of such appropriations should be based primarily on the extent of activities as reflected in the number and character of meetings held and the attendance of the members at such meetings. 4. In making a request for funds for any year, the officers of a Local Section should submit a report on the printed form approved by the Directors at their meeting on November 19, 1937. 5. A standing Committee on Local See-

Jan 1, 1942

Recognizing the fact that the problems of the committee named by the Board to prepare the "official ticket" for officers and Directors of the Institute are various and difficult; and desiring to assist this committee by setting forth some of the principles that should guide the committee and some of the qualifications that should be required of candidates, the following instructions are formulated and the Secretary is directed to publish them in MINING AND METALLURGY concurrently with the publication of the names of each newly appointed Nominating Committee and to send a copy to each member of the Committee. Each year the Nominating Committee is to select "official" candidates for eight places, as follows:, (1) President and Director (2) Vice-President and Director (3) Vice-President and Director (4) Director (5) Director (6) Director (7) Director (8) Director

Jan 1, 1939

1. Healthy and active Local Section or¬ganizations are vital factors in promoting the vigor and growth of the Institute. 2. Activity on the part of Local Sections should be recognized and stimulated by appropriation of funds from the Insti¬tute's treasury; and these appropriations should be as large as is consistent with the relative needs for other activities. 3. As between different Sections, the amount of such appropriations should be based primarily on the extent of activities as reflected in the number and character of meetings held and the attendance of the members at such meetings. 4. In making a request for funds for any year, the officers of a Local Section should submit a report on the printed form approved by the Directors at their meeting on November 19, 1937. 5. A standing Committee on Local Sec-

Jan 1, 1944

POSITIONS VACANT (Under this heading will be published notes sent to the Secretary of the Institute by members or other persons.) Metallurgist wanted for research in iron and steel. Man with experience in mills preferred. Salary $4,000. No. 13. Opening for a few technical graduates to act as instructors in mining to men at the mines under the supervision of the State mine inspector. Salary $1,800 per year. No. 14. ENGINEERS AVAILABLE (Under this heading will be published notes sent to the Secretary of the Institute by members or other persons.) Mining engineer and metallurgist open for engagement, as superintendent of mines or constructing engineer. Technically educated, with 14 years' experience in United States and Latin America in concentration, amalgamation, cyaniding, constructing. Just finished building large modern all-sliming cyanide mill in Central America. No. 18.

Jan 4, 1914

By D. G. Russell

Two techniques have been developed with which the applicability of pressure build-up analyses can be extended to include pressure data which previously have been considered virtually unusable. One of the interpretation methods makes possible the analysis of pressure build-up performance during the wellbore fill-up or after production period which occurs soon after a well is closed in. The other technique is an extension of a method for analyzing pressure build-up performance during the late-time portion of the pressure build-up which occurs after boundary eflects first begin to alter the shape of a conventional pressure build-up curve. With both of these methods it is possible to obtain estitnates of the kh product, the skin factor and the reservoir pressure. In addition, with the late-time analysis technique it is possible to obtain an estimate of the contributory drainage volume of the well being tested. This means that in some cases a check on reservoir limit test and (or) material-balance calculations can now be obtained from pressure build-ups. Both methods are slightly more time-consuming than conventional pressure build-up analysis methods because trial-and-error plots of pressure data must be made. The late-time method for analysis of pressure build-ups is in principle applicable to the late-time portion of a two-rate flow test or a pressure drawdown test. The interpretation formulas and procedures for these types of tests are also outlined. In these cases, as with pressure build-ups, it is significant that an estimate of the contributory pore volume is also obtained. On the basis of limited experience with the new techniques, it appears that satisfactory estimates of the kh product, skin factor, reservoir pressure and, for late-time analysis, contributory drainage volume can be obtained. INTRODUCTION The analysis of bottom-hole pressure build-up behavior in closed-in wells has been a a subject of interest in petroleum engineering circles for many years. In fact, few other subjects have received as much attention as pressure buildup analysis methods have. The cause for this interest is essentially twofold in nature. First, the pressure behavior of a well can normally be measured with a reasonably high degree of accuracy so that good data for analysis can be obtained. Secondly, over a fairly wide range of operating conditions, valuable information as to the quality of the reservoir rock and completion efficiency of the well can be obtained at a nominal cost. In recent years, numerous papers have been prepared on the effects of various operating conditions and reservoir heterogeneities on pressure buildup behavior. Very little work has been done, however, on extension of pressure build-up analysis methods to those pressure data which are not amenable to analysis by the present methods. The theory upon which the analysis of shut-in bottom-hole pressure build-up data is based is derived from the solution of the radial flow equation for a slightly compressible fluid for constant-rate conditions. It requires that the well be closed in for a sufficient period of time to obtain a clearly defined linear portion on the plot of observed bottom-hole pressure vs log (t + ?t)/ ?t (where At is shut-in time, and t is producing time to the instant of shut-in). From the slope of the plot and other normally obtainable data, the formation permeability, the well damage or skin factor, and the reservoir pressure at infinite shut-in time (if the reservoir were infinite) can be estimated. The successful application of this procedure depends on being able to recognize the straight-line section on the basic pressure build-up plot. The presently used pressure build-up interpretation theory also assumes that a well is closed in at the sand face and that no production into the well occurs after shut-in. In practice, of course, the well is closed in at the surface, and inflow into the well continues until the well fills sufficiently to transmit the effect of closing-in to the formation. This adjustment period is commonly referred to as the "afterproduction" or "fill-up" portion of the pressure build-up. During the period that the well fill-up effect is most pronounced, the basic pressure build-up plot is nonlinear. At later shut-in times after the effects of a drainage boundary have been felt at the well, deviation from the straight-line behavior of the pressure build-up plot also results. In many cases either of these effects or a combination of both can make the straight-line portion on the pressure build-up plot difficult to recognize. Obviously, an extension of pressure build-up analysis methods to include the afterproduction period and the period in which boundary effects are being felt would be desirable and might render valuable pressure data which for years have been considered virtually unusable. The principal reference of note concerning pressure buildup analysis during the afterproduction period is a paper by Gladfelter, Tracy and Wilsey.1 In the approach of these authors it is necessary to measure the rate of influx into the well during the afterproduction period. This is done through sonic measurements or through measurement of tubing-head and casing-head pressures simultaneously with

Jan 1, 1967

By J. A. Woolf, E. S. Leaver

The presence of soluble base metals in precious-metal ores usually precludes cyanidation as the best method of treatment. The laboratory experiments described in this paper show the possibility of cyanidation of gold-silver ores containing less than 0.5 per cent. of cyanide-soluble copper and the effect of zinc in the cyanide solution. Part I.—Copper in Cyanidation The proposed process of cyanidation of precious-metal ores containing copper is based on the regeneration of about 80 per cent. of the cyanide used in the dissolution of the copper. The method of regeneration involves a combination of the sulfide and the acid precipitation of the copper and silver. The resultant solution is made alkaline with lime, and the gold is precipitated with zinc dust. Solubility of Copper Minerals in Cyanide Solution In order to determine the solubility of copper minerals, including metallic copper, under the usual conditions for cyanidation, experiments were conducted with synthetic ores. Each ore sample was prepared by mixing the particular pure copper mineral with barren sea sand. Both the mineral and sand were ground to pass 100 mesh before they were thoroughly mixed. The percentage of copper in each head sample was determined by direct assay, excepting the metallic copper sample, which was computed on weights before mixing. Table 1 gives the results. Azurite, bornite, chalcocite, cuprite, malachite and finely divided metallic copper are readily and completely soluble under the usual conditions for cyanidation. Enargite and tetrahedrite are sufficiently soluble to cause an excessive loss of cyanide, and they also cause fouling of solutions with arsenic and antimony. Precious-metal ores containing small percentages of chalcopyrite or chrysocolla may give satisfactory returns with the usual cyanidation.

Jan 1, 1930

By Walter Harvey Weed

The Republic of Mexico is traversed by many mountain ranges, and presents a great diversity of climates, soils and geographical features, yet its grander geographic provinces are few and peculiarly well defined. The Gulf plain, the Cen tral plateau, the Sierra Madre, and the lowland or Tierra Cali ente of the western coast are the main features of the geogra phy of the Republic, and in the northern half these provinces are particularly well defined. The Sierra Madre separates the Republic into eastern and western parts, and from the City of Mexico north to the Texas line presents an almost impassable barrier to east and west travel. On the north, the first wagon road pass from east to west is at El Paso del Norte, the site of the Texan city of El Paso. Southward for many hundreds of miles the Sierra Madre, traversed by well-worn trails, over which all travel from the west coast to the interior must pass, is a stupendous barrier to social and commercial intercourse. The Sierra Madre is commonly described as a range or con geries of mountain ranges. In fact, it is, in Chihuahua at least, a great plateau, fringed by mountains on the east, trenched by deep canons in its center, and bordered by a wild and rugged complex of mountains carved out of the plateau on the west. Professional duties took me across this region from Parral westward to the Gulf of California via Guadalupe y Calvo. As it includes some of the great ore-deposits of Mexico, and its geological features have never, so far as I am aware, been described, I have prepared a diagrammatic section made from my observations on a horseback trip across the Sierra, and added such notes as seem to be of general interest.

Jan 1, 1902

By Henry Louis

Henry Louis, Newcastle-upon-Tyne, England (communication to the Secretary*).—In this paper Mr. Simons derives the various forms of revolving slime tables, of which the Harz and the Linkenbach tables are typical examples, from the old rectangular or box buddle. This I believe to be an error, at any rate if Mr. Simons attaches the same meaning as I do to the ((evolution" of a dressing appliance. By the '(evolution" of such an appliance I understand the progressive development and improvement of an appliance acting on a definite principle, such improvements having usually for their object the economy of labor in working the same, or the increase of its capacity; when an entirely new principle is introduced, I no longer look upon this as evolution from the old type, but as the origination of an independent type of appliance. The box buddle was no doubt the predecessor of the old Cornish round buddle, which was evolved from it with the object of saving the labor required to work the box buddle; both machines are horizontal-current separators, in which the separation of sands of different densities is effected by their differential rates of fall in a horizontal current of water of considerable depth. These appliances, though well suited to sands, are for obvious reasons not adapted to the treatment of slimes. The revolving tables of the Harz and similar types, on the other hand, act on the principle which I have called separation in thin films of water, and which Mr. Simons calls the film sizing principle, in which the resistance of the surface over which the pulp flows plays an essential part in determining the separation of the particles, and which is well suited to the treatment of slimes. Unlike the last principle, it will not work in deep bodies of water and cannot be used where considerable depth of material accumulates in the appliance, as in the box buddle and round buddle. As I have shown in my book, The Dressing of Minerals, p. 326, these revolving tables are a development of the appliance known variously as the flat buddle, flat table, or frame, the last name, which is the old Cornish one, being the one that I personally prefer. These primitive appliances, as well as the continuous-acting round tables described by Mr. Simons (his Figs. 10 et seq.) all work on the principle of separation in thin films, and are all adapted for the treatment of slimes; his buddles and round tables (Figs. 1 to 9) do not work upon this principle, and should therefore be sharply differentiated from the former. The evolution in each case of the continuous acting, more or less automatic, circular appliance from the primitive, intermittent, hand-worked, rectangular appliance has proceeded upon strictly parallel lines. The question of the evolution of the respective types involves a point of some importance as regards the principles of ore dressing.

Jan 1, 1915

By Norman Goss

IT is generally agreed that cold-working mechanically refines the grains into smaller fragments and with continued working these are oriented with certain crystallographic directions bearing a relation to the direction in which the metal is worked. Some of the energy expended on the metal during plastic deformation appears in the form of heat, but a very small portion remains in the metal as stored energy. The entropy, specific heat capacity, temperature at which recrystallization will just begin, density, ductility, elasticity, tensile strength, and resistance to corrosion are affected. These properties have been studied extensively and some of the changes in the physical properties due to cold-working were attributed to lattice distortion.1-8 The broadening of the K. lines on the X-ray diffraction diagrams of plastically deformed metals is believed to indicate lattice distortion, and consequently the existence of internal stresses. The evidence supporting this theory rests solely upon the observed experimental fact that the dif-fraction lines are broadened and the K a doublets are completely diffused. Elam9 has reviewed the matter of lattice distortion in relationship to the hardening of metals by plastic deformation. The X-ray diagrams of plastically deformed metals differ in general from annealed metals. The hardening of a metal was believed due to lattice distortion.9 The resolu-tion of the doublet is lost when a metal is cold-worked and the Lane spots are elongated. At one time this elongation was thought to indicate the elastic bending of the crystal planes. However, more careful work showed that the asterism was due to new orientations developed within the fragmented grains during plastic deformation. Some theories attrib-uted the hardening to fragmentation of the grains into smaller units.

Jan 1, 1940