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By Merlin H. Aylesworth

THE subject assigned to me is peculiarly appropriate to the anniversary of the birth of Abraham Lincoln. If we applied to our present problems the ideals and methods of the Great Emancipator, the future of American institutions would be so definitely assured that there would be little need to discuss the matter. The only inquiries would relate to the pace of progress, not to the possibility of progress. As a nation we have grown more and more to revere the memory of Lincoln, to honor his character, to extol his teachings and to eulogize his concepts of democracy. We rec-

Jan 1, 1940

By Harold C. Price

One year ago, that is in January, 1923, there had not been constructed a single oil-storage tank of 55,000-bbl. or more capacity with a completely electric welded roof and bottom. Today, there are at least fifty 80,000-bbl. storage tanks completed, or nearing completion, on which both the roofs and the bottoms are electric welded. It is the purpose of this paper to describe, in a general way, the construction of these welded roofs and bottoms, and to give their advantages over riveted construction. All of the following data and conclusions were obtained from observations made during the welding of tanks by the Welding Engineering Co. at Texas City, Tex., and Tonkawa and Burbank, Okla. As far as can be determined, the first electric welding on large tankage was completed in May, 1922. At that time the Empire Companies of Bartlesville, Okla., discovered a badly leaking bottom in a 55,000-bbl. tank at El Dorado, Kans. They had considered concreting this bottom, but because of the much smaller cost, decided to try electric welding; so a contract was given the Welding Engineering Co. of Bartlesville, Okla. In this instance, no new sheets were added, the bottom being repaired by electric welding of all seams and rivets, Fig. 1. In some places where the original rivets were missing, the holes were filled by welding; patch plates were also added at certain badly worn spots. This tank has since been used for over a year and a half, but no other

Jan 1, 1924

By L. G. Austin, R. R. Klimpel

This article demonstrates that the Gilvarry and Klimpel-Austin equations for the random fracture of solids are incorrect by deriving intuitively correct expressions for simple cases and showing that the foregoing equations do not reduce to right answers. It is the purpose of this article to point out serious errors in some existing treatments of the random fracture of solids. Gilvarry ' gives the equation where B(y,x) is the cumulative fraction by weight of particles which fall below size y when particles of size x are broken. The constants i, j, k contain shape factors and densities of flaws leading to propagating fracture surfaces. The authors believe this equation to be incorrect. Klimpel and usttin' give where r~ is the number of fracture planes originating from edge flaws (per L where L is the edge length of the original particle), rs is the number of fracture planes originating from flaws on the particle surface (per S where S is the surface of the original particle) and rv is the number of fracture planes originating from flaws within the particle volume. This equation is also incorrect. The failures of these equations will be demonstrated by deriving intuitively correct expressions for simple cases and showing that the Eqs. 1 and 2 do not reduce to the correct answer. In this process, the flaws in statistical reasoning inherent in the derivations of Eqs. 1 and 2 become apparent. THE KLIMPEL-AUSTIN EQUATION Eq. 2 was derived by considering a set number of fracture planes occurring spatially at random within a given particle. This case will be treated here in its simplest form: a line with 1, 2, 3, etc., fractures occurring at random. This is illustrated in Fig. 1, with the original length of the line as Vo. The breakage of a long, thin, brittle fiber is a corresponding physical case, with the volume of a fragment proportional to its length. Assuming independence of the occurrence of the fractures, the probability of any one fracture occurring in length dV is dV/V0. The probability of the first fracture occurring at a length V to V + dV is dV/Vo. For the case of only one fracture per particle, formation of a number-size distribution of the left-

Jan 1, 1969

The world's production of petroleum in 1926 amounted to nearly 150 million long tons, of which India contributed 0.72 per cent. In 1927, this figure jumped to some 172 million long tons, of which the Indian proportion, on a practically stationary production, fell to 0.64 per cent. In 1928, there was another substantial rise in the world's production, which reached the figure of over 181 million tons. In 1929, there was another jump to over 202 million tons, but in 1930 the world's production fell to about 193% million tons, in 1931 to about 187 million tons, and in 1932 to about 183 million tons, while in 1933 the production rose again to about 202 million tons, in 1934 to about 215 million tons, and in 1935 to 233 million tons1. Decreases were shown by Poland, Sarawak, Egypt, Rumania and France. All other important producers showed an increase in production, by far the largest being due to Iraq, as a result of the opening of the pipe line to the Mediterranean. The United States contributed 60.9 per cent of the world's supply in 1935, Russia 10.7 per cent, Venezuela 9.4 per cent, Rumania 3.9 per cent and Iran 3.1 per cent. In 1928, India contributed 0.64 per cent, which fell to 0.60 per cent in 1929 and rose to 0.62 per cent in 1930, 0.63 per cent in 1931, and 0.64 per cent in 1932, and fell again to 0.62 per cent in 1933, to 0.60 per cent in 1934 and to 0.50 per cent in 1935; her position on the list of petroleum-producing countries fell from eleventh in 1929 to twelfth in 1930 to 1933, her place being taken by Trinidad and to thirteenth in 1934 and 1935, owing to the production by Iraq. The production of petroleum in India (including Burma2) increased slightly from 322,025,280 gal.3 in 1934 to 322,662,336 gal. in 1935, the highest figure in the history of the industry. The increase in 1935 is due to an increase of some 4 million gallons in Assam, almost offset by a decrease of 31/2 million gallons in Burma. This increase in output in 1935 was accompanied by an increase in estimated value amounting to Rs. 22,73,550 (£170,944).

Jan 1, 1937

By William Marsh Baldwin

TWO of the most useful and important equations available to the metallurgist for the study of plastic deformation of metals are the Huber-von Mises-Henckyl-~ and the St. Venant7-10 equations. Huber-von Mises-Hengky Equation The Huber-von Mises-Hencky equation answers the question: When does plastic flow occur in metal that is subjected to a multi-axial stress? It occurs, according to this equation, when the three principal stresses,t UI, u2, and u3 satisfy the equation: (<ri - <r2)2 + (<r2 - <rsY + (ff! - <r3)* = 2Ki [i] Here K is the yield strength of the material as determined in an ordinary tensile test. If the quantities ul, 52, andas are assigned to the coordinates of a Cartesian three-dimensional system, this expression describes a cylinder whose axis of symmetry is inclined at equal angles to the three coordinate axes4s6 (Fig. I). The radius of this cylinder is .\/%K. For the purpose of simplicity, it is sometimes advantageous to ascribe the values al/K = sl, az/K = s2, UD/K = SJ to the three coordinate axes instead of the principal stress alone. In this case, Eq. I becomes (*i - s*)1 + (s2 - S3)2 + (si - SiY = 2 [2] and the radius of the cylinder becomes \/%. In the latter method of representation, a point lying inside the cylinder indicates that the metal will react elasti-cally, whereas a point lying on the cylindrical surface indicates that the metal will behave plastically. Some of the geometric features of this cylinder are worthy of study. Let us inquire first as to what interpretation may be placed upon what we will choose to call the "circles of latitude" of the cylinder (L in Fig. I) and the "meridians" of the cylinder (M in Fig. I). Circles of Latitude Circles of latitude are formed by allowing a plane, passing perpendicular to the cylinder axis, to intersect with the cylinder. Any point, P, on this circle is presumed to have the coordinates sl, SZ, and s3. The coordinates of the point resulting from the intersection of the plane and the cylinder axis will be a, a, and a (since the cylinder axis is equally inclined to the three coordinate axes). L?t US now pass a line through the point on the circle and the point on the axis.

Jan 1, 1946

By William Marsh Baldwin

TWO of the most useful and important equations available to the metallurgist for the study of plastic deformation of metals are the Huber-von Mises-Henckyl-~ and the St. Venant7-10 equations. Huber-von Mises-Hengky Equation The Huber-von Mises-Hencky equation answers the question: When does plastic flow occur in metal that is subjected to a multi-axial stress? It occurs, according to this equation, when the three principal stresses,t UI, u2, and u3 satisfy the equation: (<ri - <r2)2 + (<r2 - <rsY + (ff! - <r3)* = 2Ki [i] Here K is the yield strength of the material as determined in an ordinary tensile test. If the quantities ul, 52, andas are assigned to the coordinates of a Cartesian three-dimensional system, this expression describes a cylinder whose axis of symmetry is inclined at equal angles to the three coordinate axes4s6 (Fig. I). The radius of this cylinder is .\/%K. For the purpose of simplicity, it is sometimes advantageous to ascribe the values al/K = sl, az/K = s2, UD/K = SJ to the three coordinate axes instead of the principal stress alone. In this case, Eq. I becomes (*i - s*)1 + (s2 - S3)2 + (si - SiY = 2 [2] and the radius of the cylinder becomes \/%. In the latter method of representation, a point lying inside the cylinder indicates that the metal will react elasti-cally, whereas a point lying on the cylindrical surface indicates that the metal will behave plastically. Some of the geometric features of this cylinder are worthy of study. Let us inquire first as to what interpretation may be placed upon what we will choose to call the "circles of latitude" of the cylinder (L in Fig. I) and the "meridians" of the cylinder (M in Fig. I). Circles of Latitude Circles of latitude are formed by allowing a plane, passing perpendicular to the cylinder axis, to intersect with the cylinder. Any point, P, on this circle is presumed to have the coordinates sl, SZ, and s3. The coordinates of the point resulting from the intersection of the plane and the cylinder axis will be a, a, and a (since the cylinder axis is equally inclined to the three coordinate axes). L?t US now pass a line through the point on the circle and the point on the axis.

Jan 1, 1946

By Thomas L. 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. However, 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 magnesian limestone. General Geology Geologic relations of the ore deposits of this district are more or less similar to those of many Appalachian districts. The lowermost Cambrian formation, heretofore called Weisnerl in this region, supposedly partly or. wholly equivalent to the Erwin and Hesse quartzites as recognized to the northeast, is overlain conformably by the Shady† formation, also of Lower. Cambrian age. In the Cartersville district, the sedimentary rocks of these formations were folded with increasing intensity eastward, and were recrystallized.

Jan 1, 1941

By Thomas L. 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. However, 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 magnesian limestone. General Geology Geologic relations of the ore deposits of this district are more or less similar to those of many Appalachian districts. The lowermost Cambrian formation, heretofore called Weisnerl in this region, supposedly partly or. wholly equivalent to the Erwin and Hesse quartzites as recognized to the northeast, is overlain conformably by the Shady† formation, also of Lower. Cambrian age. In the Cartersville district, the sedimentary rocks of these formations were folded with increasing intensity eastward, and were recrystallized.

Jan 1, 1941

By J. W. Buch

IN THE FIELD of track haulage, interest has seemed to center on the question of larger mine cars both for handling material from loading point to shaft bottom or surface, and for shuttle service. Saving of time in car changing is obvious if larger cars are used. In addition, shorter trips result where car transportation is from face to opening without transfer. This also brings about side-track and equipment savings. Track shuttle service, using large automatic-dump cars (10 tons) between loading machines and trip loading point, has been a satisfactory solution for the operator who mechanizes a working mine regularly equipped with a large number of small mine cars. This development in track shuttle haulage, has made track installation and maintenance increasingly important, requiring closer supervision.

Jan 1, 1942

By Joseph E. Pogue

FOR a number of years the petroleum department of The Chase National Bank has been making a continuing study of the financial aspects of thirty oil companies. (See Pogue and Coqueron, "Financial Analysis of Thirty Oil Companies," pamphlet, The Chase National Bank, November 1945, for data covering eleven years, 1934-1944, and the list of the companies making up the group. See also "Capital Employed in the Petroleum Industry," by the same authors, M&M, November 1944.1 This group represents a large sample of theAmerican petroleum industry, covering about two thirds of the business. Certain aspects of this study concern the capital employed in crude oil production, the main features of which arc presented in this paper.

Jan 1, 1946

By Eric R. Jette

In order to control a chemical process by other than empirical, rule of thumb methods, two types of knowledge concerning the reactions involved must be available: (1) the thermodynamics of the reactions, and (2), by no means less important for efficient operation, the mechanisms and kinetics of the reactions. Information on the thermodynamic side enables the operator to decide upon initial and final conditions, whether heat must be added or removed from the system, whether the reactions proceed farthest in the desired direction at high pressure or low, etc. Knowledge of the mechanisms involves the determination of the individual steps by which an initial set of reactants, under given conditions, proceed to give the desired final products and kinetic studies upon which the mechanisms are based give the speed at which each of these reactions or steps take place. Thus thermodynamic studies of a reaction enable the operator to control the direction and extent to which the reaction can proceed, while kinetic studies enable him to control rates and thus the time efficiency of the operations. The thermodynamics set the limit to which the reacting system approaches; the kinetics tell how fast the system actually approaches this limit. The two types of information are complementary and not antagonistic even though in discussing the mechanism the introduction of thermodynamics is entirely needless and generally of no assistance, while in thermodynamic studies mechanism need not even be mentioned. Heterogeneous Reactions The thermodynamic side of metallurgical reactions has received much attention in the past; the mechanisms, relatively, very little. The main reason for our present lack of information on the mechanisms of these reactions lies in the fact that every one of importance is a heterogenkous reaction; i. e., the substances involved in the reaction exist in more than one phase, while, if we neglect the large amount of work which has been

Jan 1, 1931

By George W. Maynard

(Pittsburg Meeting, March, 1910.) AT the Pittsburg meeting of the Institute, May, 1879, I made the first announcement in America of the results obtained by Sidney Gilchrist Thomas and Percy C. Gilchrist, ill their efforts to eliminate phosphorus in the manufacture of steel in the Bessemer converter and the open-hearth furnace.1 The first published statement in an American newspaper was a reprint of the first Thomas-Gilchrist paper, 2 which I sent to J. C. Bayles, at that time the editor. At the suggestion of many friends who were present at the Pittsburg meeting, and others who are cognizant of the beginnings of the process in the United States, and for the information of the younger generation of the iron and steel fraternity, I have thought it eminently proper that the history of the process in detail should be given where I made the first announcement and where the process has had its largest development. During my residence in England, from April, 1873, to February, 1879, and as a member of the Iron and Steel Institute since 1874, I was present at many of its meetings during those years. At nearly -every meeting the burden of discussion was the question of the use of pig-iron containing phosphorus in the. manufacture of steel by the Bessemer or the open-hearth process. In my biographical notice of Thomas;3 read at the New York meeting of, the Institute, February, 1885, I show that the working-out of the process was not a hap-hazard or accidental inspiration, but the culmination of many years of investigation of experiments and theories which had been carried on and advanced by chemists and metallurgists at home and abroad. 1 Trans., viii., .5 (1879-80). 2 The Iron Age, vol. 22, No. 17, p. 3 (Oct. 24, 1878). 3 Trans.. xiii., 785 to 791.

Jul 1, 1910

By PERCY E. BARBOUR

SECONDARY copper1 has &come more or less of a bugbear generally. What is its influence is often the subject of heated argument. The inedapable fact usually quoted is that since in 1929 primary production of copper in the United States was 1,026,348 tons and secondary production was 626,550 tons, there- fore, 0.6 lb. of secondary is produced for every pound of primary, and "How can you get around that?" The matter seems very plain, now that I have reached my conclusions, but they are the result of much laborious study and research. I shall show that&apos; the production of secondary copper is not 0.6 per lb. of primary, in spite of statistical appearances; that the production of secondary is a function of primary production rather than of price; that secondary production has &apos;only a sub-. ordinate influence on the price of copper and then only in abnormal times; that there is not an accumulating reservoir of secondary from which the country is some- time to be drowned in copper, as is believed by some, or a reservoir from which we are going to draw much needed and more or less inexhaustible stores in the future, as is believed by others; and finally, that the United States always produces more copper than it uses and exports the surplus. These are all controversial points, and for that reason and to anticipate argument I have set forth my reasoning in considerable detail.

Jan 1, 1931

By E. J. Ripling

TUBES may be produced by a large number of forming processes, the most common of which will be discussed analytically in this paper. In no case will the stress analysis for any given tube producing process be derived formally for where such analyses are available, they may be referred to readily. Rather, emphasis will be placed on the interpretation of the theory of the different processes, few of which are developed to a state that will allow rigorous mathematical analyses, in an attempt to give a rational description of the effects of the different variables involved in each method. Tube producing methods can be divided into two groups: Those used to form shells, and those used to further work these shells into a shape more suitable for their final use. Among the first group are included roll piercing, extrusion and cupping for seamless shells, and bending with welding for welded tubes. The re-forming processes include sinking, drawing with a plug, and drawing with a rod. Only the plastic forming operations will be discussed here; other forming processes such as casting shells will not be considered. PRODUCTION OF SHELLS Shells for Seamless Tubing Piercing: The extremely important process of forming an axial hole in a billet by oblique rolling never has been analyzed satisfactorily, although a certain amount of experimental work relating to this process has been conducted. There are a number of factors that make piercing difficult to analyze; one of these is the fact that piercing is not a problem in plasticity, but one in fracturing, and the laws of fracturing are even less well understood than those of plasticity. If, however, it is assumed that fracturing occurs on a surface as a result of tensile stresses acting normal to this surface, piercing can be analyzed qualitatively by examining the stresses established in the oblique rolling process. To determine the origin of the tensile stresses that are thought to effect piercing, it will be necessary to know the angular relationships between the maximum stresses that are established in piercing. These angles quite frequently can be determined in a plastic deformation process by an examination of the deformed product. For example, consider the stresses established when a tensile test is conducted on a rectangular cross-sectional specimen of pearlitic steel. When stretched, this material first flows plastically, exhibiting the well-known yield jog on a stress-strain curve. The formation of the slip areas that give rise to the yield jog can be detected during the straining, since these flowed areas cause depressions on the specimen surfaces which can be seen if the surfaces are polished highly. The plastically strained areas also can be found after the specimen has been stretched to a strain not exceeding the yield jog, by sectioning the test piece and. etching these sections with Fry&apos;s etch. With this etchant, it is possible to dis-

Jan 1, 1951

By Arthur Crowfoot

Page IntRodUction ................... The Round Table in Lake Superior Practice .........420 Early Use of Revolving Round Table in Butte District...... Use oF the Round Table at GREat Falls foR Sand-Slime Feed ., . The Round Table for Fine Slime........,.... Construction of Slime Plant at Great Falls..... &apos;..... 424 Tests on Wood, Linoleum, and Cement Decks.........426 Central Feed Apron Removed ....&apos;......... Re-treatment of Round-Table Tailing........... Determination of Conditions for Round-Table Treatment of Slimcs ... 430 Variation in Slope of Round-Table Deck........ ,... The Steel-Frame Cement-Deck Round Table ........ Tests on Cement and Canvas Dock Surfaces ..: ..... Conoidal Deck Round Tables............. Results with Sand-Slime Feed on Conoidal Deck....... Conclusions from Preliminary Tests on Conoidal and Conical Decks ... 446 Discussion of Results of Four-Day Test on Conical and Conoidal Decks . 452 Discussion of Results of Eight-Day Test.......... Qualitative Sampling of Concentrates Across Conical Deck.... Summary of Slime-Plant Practice............ Suggested Flow Sheet for Slime Classification and Treatment.... Conclusion...................467 Introduction The principal object of this paper is 60 presest, data on the development of the revolving convex round table as a concentrator for the through 0.07-mm. slimes from the ores of the Butte district, although some brief notes on the earliest recorded use of this type of concentrating table in the ore-dressing plants of the Lake Superior region and of the Butte district are also presented. The revolving convex round table belongs to the class of concentrating tables known as film-sizing. tables, these tables using the relative transporting power of a film, or thin sheet of water, as it flows over a quiet inclined surface, to separate the minerals of a sorted product. The grains of heavy mineral move down the slope of the table deck slowly, or, in some cases, not at all, after the initial force of the feed entry VOL. XLIX.—27

Jan 1, 1915

By Augustus Locke

WHY should I, a geologist, be coming before you to talk about finding ore? Certainly, the great discoveries of the past have not been made by geologists, but by men of very different tastes and training. If, in the year 1800, the course of ore discovery could have been foreseen, there would have been no reason to put it into the hands of geologists or other men of technical preparation. It was not geologists but explorers, Indian fighters, prospectors, manual laborers, and hardy financiers, who initiated the American mining industry. Then why this association of geological technique with ore finding? Why this feeling that the way to find ore is to apply to the problem what we call geo- logical principles? Well, to put it broadly, the old method has run out on us. It no longer works. Or, to put it another way, the cost of finding ore by the old method has mounted so high that one old district after another has become, practically speaking, dead, and various other old districts that are still going apparently at full strength are actually beginning to limp, and, with the cost of discovery mounting yearly, to fear, more than they will acknowledge, that the end is approaching.

Jan 1, 1926

By C. W. Goodale

I. INTRODUCTION. In the summer of 1909 the Boston & Montana reduction department of the Anaconda Copper Mining Co. completed a new flue system, at a cost of about $1,100,000, and -is this includes the largest and highest chimney in the world, and some new features of flue construction, a description will be of interest. At the Spokane meeting of the Institute in September, 1909, a brief mention was made of this flue system, in discussing Mr. Brunton&apos;s presidential paper on the Progress of Metallurgy in the West, and a promise was given that when a long enough time had elapsed, so that operating results could be given, a paper would be offered. The smelting plant includes blast furnaces, MacDougall roasters, gas-fired reverberatories, and converters.

Jan 8, 1913

By A. L. Holley

THIS process is performed in the Pernot puddling furnace; it removes from 75 to 80 per cent. of the phosphorus, most of the sulphur, and practically all the silicon, from crude iron, in from five to eight minutes. It has been in regular use since March, 1877, and has prod uced over seventeen thousand tons of washed metal for the open-hearth furnace. During two years, nearly all, and lately, all the open-hearth steel produced in these works has been made from about 5 tons of washed pig and 2 tons of scrap per open-hearth furnace heat. There are 12 open-hearth furnaces, of which 4 to 9 are running, according to the state of orders. A large amount of highly phosphoric iron from France and Belgium has been also washed and then puddled for parties who have taken, or are expected to take, licenses. The washing of pig for puddling, however, is not a practice at Krupp&apos;s works, because pure pigs are nearly as cheap as impure ones. The author and his assistant, Mr. Laureau, spent, during the last month, three days at Krupp&apos;s works, examining this process. They copied out of the office books characteristic analyses and physical tests, some of which are given herewith. They also brought hone many samples of pig, cleaned metal, puddle bar, and steel, which they saw treated. Analyses of some of these samples appear in Table IV. As there are no blast furnaces at Essen, the iron is melted in two Bessemer cupolas with fore-hearths; they melt 12g pounds of iron with 1 pound of coke. The metal is run by a spout from the fore-hearth into an opening at the side of the main door of the washing-furnace. The Washing furnace.-This is a regenerative gas furnace. It has a Pernot revolving-hearth of 12 feet external diameter and 3 feet depth. (See Plate.) The four regenerator chambers have 780 cubic feet capacity, which is about the same as the average regenerator capacity of open-hearth steel furnaces of equal tonnage. The lining is 13 inches thick on the sides and 9 inches on the bottom, thus giving a hearth 9 feet 10 inches by 2 feet 3 inches deep. The lining is composed of lumps of highly refractory ores

Jan 1, 1880

By A. L. Holley

This process is performed in the Pernot puddling furnace; it removes from 75 to 80 pel. cent. of the phosphorus, most of the sulphur, and practically all the silicon, from crude iron, in from five to eight minutes. It has been in regular use since March, 1877, and has produced over seventeen thousand tons of mashed metal for the openhearth furnace. During two years, nearly all, and lately, all the open-hearth steel produced in these works has been made from about 5 tons of washed pig and 2 tons of scrap per open-hearth furnace heat. There arc 12 open-hearth furnaces, of which 4 to 9 are running, according to the state of orders. A large amount of highly phosphoric iron from France and Belgium has been also washed and then puddled for parties who have taken, or are expected to take, licenses. The mashing of pig for puddling, however, is not a practice at Krupp&apos;s works, because pore pigs are nearly as cheap as impure ones. The author and his assistant, Mr. Laureau, spent, during the last month, three days at Krupp&apos;s works, examining this process. They copied out of the office books characteristic analyses and physical tests, some of which are given berewith. They also brought home many samples of pig, cleaned metal, puddle bar, and steel, which they saw treated. Analyses of some of these samples appear in Table IV. As there are no blast furnaces at Essen, the iron is melted in two Bessemer cupolas with fore-hearths; they melt 124 pounds of iron with 1 pound of coke. The metal is run by a spout from the forehearth into an opening at the side of the main door of the washingfurnace. The The washing-furnace.—This is a regenerative gas furnace. It has a Pernot revolving-hearth of 12 feet external diameter and 3 feet depth. (See Plate.) The four regenerator chambers hare 780 cubic feet capacity, which is about the same as the average regenerator capacity of open-hearth steel furnaces of equal tonnage. The lining is 13 inches thick on the sides and 9 inches on the bottom, thus giving a hearth 9 feet 10 inches by 2 feet 3 inches deep. The lining is composed of lumps of highly refractory ores

Jan 1, 1880

By A. H. Geisler, F. Keller

Some of the important changes that take lace in the structure of aluminum alloys are largely submicroscopic in character. This is especially true of the changes that accompany age-hardening and recrys-tallization. Although improved metal-lographic practices have been helpful in indicating some of these changes indirectly, results are limited by the resolving power of optical microscope lenses. The electron microscope, however, provides a new and important means for investigating the fine structure of metals in a range not possible heretofore. It is anticipated that this microscope will yield new and useful information to metallurgists when suitable techniques are developed to utilize its very high resolving power. Several unique methods have been devised to permit the examination of the structure of opaque samples by the electron microscope. These are all based 011 the principle of producing a very thin film that represents the prepared surface of the opaque metal sample, which can be examined in the transmission microscope; however, the available methods fall into three categories, depending on the manner in which the film is obtained. With the oxide-film method developed by Mah13-l7 a very thin surface layer of the metallographic sample is converted into oxide by a thermal, chcmical or anodic treatment. .After removal from the metal sample by one of the special techniques described by Evans,l9 this oxide film is examined in the electron microscope, and is found to portray the structure of the original metal surface. Films formed on aluminum,8,l7 nicke1,7 iron3,8,9 and a nickel-beryllium alloyl1 by heating; films formed on iron8,9 by chemical action; and films formed on aluminum3-&apos;" by anodic oxidation, have been examined. The other two are more recent methods developed principally in this country; they consist in making the thin film in the form of a mold or replica of the surface contour of an etched sample. With the negative replica method the thin film is made directly on the sample; with the positive replica method it is made on a negative reproduction of the sample. With both methods, variations in the contour of the metal sample, caused mainly by etching, produce variations in the thickness of the surface replica. Because of the direct dependence of the amount of scattering of the illuminating electrons upon the thickness of the film penetrated, only the variations in thickness of the replica are responsible for tones in the electron image. Negative replicas are made by forming a thin film of some suitable material directly on the polished and etched metal sample, and derive their name from the fact that after removal from the sample they have the high and low points in the sample reversed, as shown in Fig. I. Nega-

Jan 1, 1944