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By S. B. Christy

Jan 1, 1902

By Kenneth Robertson

THEREi9 probably less known of this subject than of any other connected with the metallurgy of iron. In all the books that treat of this mattes, there are given analyses of slags, their chemical formulae, the loss of iron, etc. ; but few, if any, give the character of the iron made at the time ; none give analyses and physical characteristics of the ores and limestones used, and they present merely isolated examples from various furnaces, and consequently one is more frequently puzzled than enlightened after reading them. During two years I have had occasion to analyze the slags and many of the pig-irons from two furnaces, and for this article I have made analyses of all the different grades of pig made by them. A

By H. Foster Bain

Probably no more significant change has come into the lives of men in the past two hundred years than their shift from major dependence on plants and animals to major dependence on minerals. From the dawn of history, nay from long before that dawn, food and clothing had been man's main concern. The wandering of the tribes in pastoral ages was in search of grass for their cattle; the patient work of the "man with the hoe" has ever been to supply food for himself and family and if he accomplished so much he had little strength, energy, or ambition for other things. The great civilizations of the past arose in the fertile valleys where food supply was abundant or on shores where by grace of the wind and primitive wooden ships food could, if needed, be imported. Provision for the "seven lean years" by storing the abundance of the seven fat years was long held up as the highest example of statesmanship and the ambitions of the Roman populace did not go beyond bread and circuses, the former the product of a plant and the latter involving essentially contests of men and other animals. Through all those centuries of want, misery, and warfare it was, for example, an axiom that "an army fights oh its belly." Now an army rides to the battle line in trucks; its members stand up and fight with tons and tons of metal and other minerals. Food supply is assumed, and rightly so, for in this modern world of ours shortage of food is chargeable at once to poor organization or deficiency of transport. The areas in which famines occur are those in which the one or the other

Jan 1, 1932

By A. A. Venghiattis

A rational approach to the selection of the appropriate perforator to use in each specific zone of an oil well is presented. The criteria presently in use for this choice bear little resemblance with actual down-hole condilions. These environmental conditions affect the elastic properties of rocks. One of these elastic properties, acoustic velocity, is suggested as the leading parameter to adopt for the choice of a perforator because, being currently measured in the natural location of the formation, it takes into account all of the effects of compaction, saturation, temperature, etc., which are overlooked in the laboratory. Equations and curves in relation with this suggestion are given to allow the prediction of the depth of perforation of bullets and shaped charges when an acoustic log has been run in the zone to be perforated. INTRODUCTION When an oil company has to decide on the perforator to choose for a completion job, I wonder if it is really understood that, to date, there is no rational way of selecting the right perforator on the basis of what it will do down-hole. This situation stems from the fact that the many varieties of existing perforators, bullets or shaped charges, are promoted on the basis of their performance in the laboratory, but very little is said on how this performance will be affected by subsurface conditions such as the combination of high overburden pressure and high temperature, for example. The purpose of this paper is to show the limitations of the existing ways of evaluating the performance of perforators, to show that performances obtained in laboratories cannot be extended to down-hole conditions because the elastic properties of rocks are affected by these conditions and, finally, to suggest and justify the use of the acoustic velocity of rocks, as the parameter to utilize for the anticipation of the performance of a perforator in true down-hole environment. EVALUATING THE PERFORMANCE OF A PERFORATOR It is natural, of course, to judge the performance of a perforator from the size of the hole it makes in a predetermined target. Considering that the ultimate target for an oilwell perforator is the oil-bearing formation preceded in most cases by a layer of cement and by the wall of a steel casing, the difficulties begin with the choice of an adequate experimental target material. For obvious reasons of convenience, the first choice that came to the mind of perforator designers was mild steel. This is a reasonable choice for the comparison of two perforators in first approximation. Mild steel is commercially available in a rather consistent state and quality, and is comparatively inexpensive. The trouble with mild steel is that it represents a yardstick very much contracted; minute variations in depth of penetration or hole diameter and shape may be significant though difficult to measure. The penetration of projectiles in steel being a function of the Brinell hardness of the steel (Gabeaud, O'Neill, Grun-wood, Poboril, et al), it is often difficult to decide whether to attribute a small difference in penetration to a variation on the target hardness or to an actual variation on the efficiency of the projectile. Another target material which has been widely used for testing the efficiency of bullets or shaped charges in an effort to represent a formation—a mineral target as opposed to an all-steel target—is cement cast in steel containers. This type of target, although offering a larger scale for measuring penetrations, proved so unreliable because of its poor repeatability that it had to be abandoned by most designers. The drawbacks of these target materials, and particularly their complete lack of similarity with an oil-bearing formation, became so evident that a more realistic target arrangement was sought until a tacit agreement was reached between customers and designers of oilwell perforators on a testing target of the type shown on Fig. 1. This became almost a necessity about seven years ago because of the introduction of a new parameter in the evaluation of the efficiency of a perforator, the well flow index (WFI). The WFI is the ratio (under predetermined and constant conditions of ambiance, pressure and temperature) of the permeability to a ceitain grade of kerosene of the target core (usually Berea sandstone) after verforation. to its vermeabilitv before perforation. The value of this index ;or the present state if the perforation technique varies from 0 to 2.5, the good perforators presently available rating somewhere around 2.0 and the poor ones around 0.8, There is no doubt that, to date, the WFI type of test is by far the most significant one for comparing perforators. It is obvious that a demonstration of a perforator

By C. G. Dunn, F. W. Daniels, M. J. Bolton

IN recent papers on interface energies in metals¹,² the concept of an equilibrium of forces has been used in the measurement of interfacial tensions. Mathematically the equilibrium of three forces is given by the relations: where the 2's are the interfacial tensions (interface energies per unit area of interface) of three phases or grains meeting at angles 21 22 and 23 (212 relates to the 1-2 boundary formed by grains 1 and 2;223 to the 2-3 boundary, etc.). If these relationships are valid, one can calculate relative values of the interface energies from measured boundary angles on specimens which have been brought to equilibrium. Since Eq 1 may be derived through a mathematical process of minimizing the grain boundary energy under the restriction that the ?'s be independent of boundary orientation: the concepts of surface tensions and equilibrium of forces are not particularly essential. To deal with the general case involving dependence of boundary energy on boundary orientation, it becomes desirable to drop certain concepts formerly held (namely that energy per unit area is identical with force per unit length or surface tension) and to use the energy concept alone. It is appropriate, therefore, to use E in place of ? in deriving and using the more general equations that express the anisotropic nature of the grain boundary energy. Herring3# ' recently has derived the required general equations using the principle of minimization of energy. Specifying the boundary orientations in terms of angles (4) measured with reference to crystal axes within the grains, Herring's equations take the form E23 + E21 cos?8 + E12 cos?2 — sin ?12 + sin?2-?E12/?12 =O [2] where the partial derivatives are measured in the direction of counterclockwise rotation of the boundaries. Eq 2 implies that an infinitesimal displacement of the triple point along the 2-3 boundary produces no change in the boundary energy. Similar equations apply for infinitesimal displacements along each of the other two boundaries. From such equations Herring obtains the following general relationship (1 + E1 E2) sin?8 + (E2 — E1) cos?3 ________ E38______________ = (1+ E2 E8) sin ?1+ (E3— E2) cos ?1 __________^5____________[3] (1 + E sin ?2, + (E1 — E8,) COS ?2 1 E28 where E1 = 1/E23- E25 and PC and c8 have similar expressions. It is apparent that Eq 3 reduces to Eq 1 when the c's vanish. Eq 3 also reduces to Eq 1 when the E'S are all equal. Shockley and Read' have pointed out one limitation to these equations. When E plotted versus 4 appears as an energy cusp, as their theory requires, for example, for the energy near a twin boundary position, then Eq 3 (and therefore Eq 1 also) no longer applies if one boundary is in the minimum energy position. One of the equations of form Eq 2, however, applies if the infinitesimal displacement is along the boundary associated with the energy cusp. From the foregoing treatment it will be apparent that equilibrium angles alone are not sufficient in general for calculating relative interface energies.

Jan 1, 1951

Application of Kutter's Formula to Gases Discussion of paper by F.-ERNEST BRACKETT, presented at the Pittsburgh Meeting and issued, as Pamphlet No. 1578-A-F, with MINING AND METALLURGY, June. 1926. C. S. WITHERELL, New York, N. Y..(written discussion).-There is no reason to doubt that the relationship between the rate of, flow and. the impelling force of all fluids can be expressed by a general typical equation that takes cognizance of all relevant factors such as density, viscosity (or its reciprocal, mobility) and nature of channel-walls. Most fluids that are commonly conveyed by flow in confined channels are so highly mobile that they may be considered non-viscous, hence for these fluids the factor of viscosity does not need to appear in the equation. Water is the outstanding example of this class of fluids and its dynamic behavior has been so thoroughly investigated that proven formulas pertaining thereto, be they rational or empirical, would naturally serve as prototypes for the other non-viscous fluids. As non-viscous fluids can be classed all gases and vapors, most unsaturated aqueous solutions, gasoline, alcohol, etc. Viscous fluids comprise those that have a sluggish flow such as most oils, tar, molasses, etc., the' high viscosity of which is due to shearing resistance between molecules, a force that must betaken into account in figuring the flow of fluids of this class.

Jan 10, 1926

By William Hurst

This is a presentation of the diffusivity theory for the calculation of the water drive on an oil reservoir in which the history of reservoir pressure with time are the essential parameters for the determination of the rate and cumulative water encroachment into a field. The main body of the paper is essentially the application of the principles underlined here to actual field data. It consists of the work plots of the radial-flow case, and includes a discussion of an illustrated problem for which the water-drive calculations are treated in conjunction with the volumetric-balance equation. The appendix is a mathematical treatment of the linear, radial, and spherical cases of water influx into a reservoir. Introduction The evaluation of oil reserves and the prediction of pressure behavior with different rates of production are related to the volumetric balance of the fluids entering and leaving the space occupied by the oil and gas originally present in the formation; that is to say, important information can be gleaned from a volumetric study of the oil, gas, and water produced from a formation as it affects the extent of change in volume of oil zone, the gas cap, and the amount of water influx from the adjoining water sands. It is not the purpose of this paper to enter into a discussion of the equation of volumetric balance, in which such pertinent information as subsurface sampling and the measurement of reservoir pressures play a predominant part, as this has been discussed in detail by others.1,2 However, there is an inherent difficulty that has limited the general application of this equation to a study of oil reservoirs; that is, the insufficient knowledge of the analytics for expressing the water drive on a field as a function of reservoir pressure. This to a large degree has been overcome and it is the purpose of this paper to present this theory in such form as to be applicable for reservoir calculations. Water Drive If the amount of oil originally in place and the gas space are known, it is a relatively simple matter to determine, by the volumetric equation, the cumulative water influx into a reservoir from the adjoining water sands. Often, however, the oil reserve as well as water influx must be 'determined, and in order to be able to make this calculation it is essential to assign a mathematical relationship for the varying water term that is compatible with conditions known to exist in the formation and gives an accuracy acceptable for engineering calculations. Various equations have been employed empirically by different investigators in making reservoir studies of water drive. One form used by Schilthuis2 expresses the rate of water influx into a reservoir at any time as proportional to the pressure

Jan 1, 1943

By William Hurst

This is a presentation of the diffusivity theory for the calculation of the water drive on an oil reservoir in which the history of reservoir pressure with time are the essential parameters for the determination of the rate and cumulative water encroachment into a field. The main body of the paper is essentially the application of the principles underlined here to actual field data. It consists of the work plots of the radial-flow case, and includes a discussion of an illustrated problem for which the water-drive calculations are treated in conjunction with the volumetric-balance equation. The appendix is a mathematical treatment of the linear, radial, and spherical cases of water influx into a reservoir. Introduction The evaluation of oil reserves and the prediction of pressure behavior with different rates of production are related to the volumetric balance of the fluids entering and leaving the space occupied by the oil and gas originally present in the formation; that is to say, important information can be gleaned from a volumetric study of the oil, gas, and water produced from a formation as it affects the extent of change in volume of oil zone, the gas cap, and the amount of water influx from the adjoining water sands. It is not the purpose of this paper to enter into a discussion of the equation of volumetric balance, in which such pertinent information as subsurface sampling and the measurement of reservoir pressures play a predominant part, as this has been discussed in detail by others.1,2 However, there is an inherent difficulty that has limited the general application of this equation to a study of oil reservoirs; that is, the insufficient knowledge of the analytics for expressing the water drive on a field as a function of reservoir pressure. This to a large degree has been overcome and it is the purpose of this paper to present this theory in such form as to be applicable for reservoir calculations. Water Drive If the amount of oil originally in place and the gas space are known, it is a relatively simple matter to determine, by the volumetric equation, the cumulative water influx into a reservoir from the adjoining water sands. Often, however, the oil reserve as well as water influx must be 'determined, and in order to be able to make this calculation it is essential to assign a mathematical relationship for the varying water term that is compatible with conditions known to exist in the formation and gives an accuracy acceptable for engineering calculations. Various equations have been employed empirically by different investigators in making reservoir studies of water drive. One form used by Schilthuis2 expresses the rate of water influx into a reservoir at any time as proportional to the pressure

Jan 1, 1943

By Colin C. Rae

The absence of paraffin and other oil hydrocarbons in the soil although they are concentrated in extensive deposits in some localities, the common distribution of plant remains through many formations that are not productive for oil, and many other factors, seem to indicate the existence of an intermediate organic compound between the complex plant compounds and the petroleum hydrocarbons; and much evidence points to the humus acids or associated organic compounds, which are probably collected by surface waters and concentrated in certain areas by means of precipitation by electrolytes, which would be contained in sea water or possibly in various inland seas or lakes. Present-day Evidence There are many present-day evidences of the association of petroleum with humus acids. Binney, in 1912, made observations without explanations on the peat mosses of Down Holland, England, where he found petroleum being formed by decomposition in the presence of an infiltration of sea water. The analysis of a typical peat will show its relationship to the humus acids under consideration. Sample No. 1, SamplE No. 2. PXr Cent. PER CENt. Water......................... 20.0 29.6 Ash.......................... 3.0 3.05 Fiber.......................... 47.0 54.95 Humus acids................ 30.0 12.50 J. D. Haseman and others have noted the association of asphalt and hydrocarbons with the swampy, boggy areas, particularly adjacent to the sea. Many of the rivers carry much humus acid in solution, and some tropical rivers carry in the aggregate millions of tons of humus each year. The amount of humus is a variable factor, depending on climatic conditions, and on the salts and alkalies present in the water, also on the density and temperature.

Jan 1, 1923

By Colin C. Rae

The absence of paraffin and other oil hydrocarbons in the soil although they are concentrated in extensive deposits in some localities, the common distribution of plant remains through many formations that are not productive for oil, and many other factors, seem to indicate the existence of an intermediate organic compound between the complex plant compounds and the petroleum hydrocarbons; and much evidence points to the humus acids or associated organic compounds, which are probably collected by surface waters and concentrated in certain areas by means of precipitation by electrolytes, which would be contained in sea water or possibly in various inland seas or lakes. Present-day Evidence There are many present-day evidences of the association of petroleum with humus acids. Binney, in 1912, made observations without explanations on the peat mosses of Down Holland, England, where he found petroleum being formed by decomposition in the presence of an infiltration of sea water. The analysis of a typical peat will show its relationship to the humus acids under consideration. Sample No. 1, SamplE No. 2. PXr Cent. PER CENt. Water......................... 20.0 29.6 Ash.......................... 3.0 3.05 Fiber.......................... 47.0 54.95 Humus acids................ 30.0 12.50 J. D. Haseman and others have noted the association of asphalt and hydrocarbons with the swampy, boggy areas, particularly adjacent to the sea. Many of the rivers carry much humus acid in solution, and some tropical rivers carry in the aggregate millions of tons of humus each year. The amount of humus is a variable factor, depending on climatic conditions, and on the salts and alkalies present in the water, also on the density and temperature.

Jan 1, 1923

By Alexander Bowie

In many places throughout the Western mountain plateau regions of the United States coal beds in place have been burned over very extensive areas, the fire evidently originating on the nakedly exposed outcrop of the coal bed and gradually burning its way into the bed for considerable distances under very heavy cover. The surface evidences of the burned-out coal beds are seen in the calcined and discolored rocks overlying the places of the outcrops. The greater the mass of the burned coal the higher the results of its combustion can be seen in the overlying strata. I have noted many instances of this condition in the States of South Dakota, Wyoming, Colorado, New Mexipo, and Arizona. In the lignite fields of Dakota and Wyoming I noted stretches of level country many square miles in extent where the surface rooks were roasted and vitrified by the burning of a great bed of lignite lying nearly level and with a light cover; this is probably the most favorable natural condition for the burning out of a coal bed. The less the depth of the rock covering overlying the coal bed, the better the chance for a continuous supply of air to the fire; but when the coal bed dips heavily into the ground, or even if level, if it passes under a hill or mountain which gives the bed a heavy covering of strata, the fire has more chances of being extinguished from natural causes than in the first condition described. The distance which a crop fire may extend into a coal field is very much influenced by the dip, the thickness of the coal bed, and the nature of the rock covering immediately overlying it. In reasoning on this subject, it would seem logical to assume in the case of a coal-bed cropping at the base of a hill and dipping into it, with an extensive drainage surface above the crop line, that a crop fire would be promptly extinguished by the caving in of the overlying strata and the precipitation of the rainfall from the drainage surface above the outcrop through the breaks formed in the caving strata. This consideration would be more or less effective according to the climate of the location and the nature of the overlying strata. In a humid climate where the rainfall was heavy the water from the natural precipitation alone would probably extinguish a crop fire before it could work its way very far under cover, but in an arid climate this preventive does not seem to be effective.

Jan 1, 1915

A development which could prove significant was the announcement on September 18 by Lone Star Industries, Inc., Greenwich, Conn., that the Snyder process which utilizes shock phenomena to break down ore in seconds, is operational. J. R. Kringel, chairman and president of Lone Star, says this about the process: "This new approach to the comminution of ores not only provides better mineral liberation at lower capital and operating costs, but it also makes a significant contribution toward the more efficient utilization of the country's rapidly depleting mineral reserves." The Snyder process consists of loading the material into a chamber, introducing a compressible working fluid such as steam under 300-500 psi, or as low as 80 psi, and then opening a millisecond-action discharge valve, causing the material to become entrained in the expanding fluid. The mixed fluid moves through a duct toward a discharge zone at near-sonic velocity, and is subject to a variety of extreme shock phenomena which accomplish the desired size reduction and mineral liberation.

Jan 11, 1972

By R. V. Norris

LAST October, Mr. R. V. Norris and Mr. Matthew C. Fleming were appointed to represent the Institute at the Second National Industrial Tax Conference, which was held in New York City on Oct. 22 and 23. After reading the report submitted by the Committee, Mr. Norris and Mr. Fleming addressed the following to the Tax Committee of the National Industrial Conference Board: The tentative report of the Tax Committee of the National Industrial Conference Board was received too late to make it possible to lay it before the Board of the Institute, and the undersigned themselves have not had sufficient time to digest its interesting contents and recommendations carefully. So that we desire to make it clear that the comments we make on the report are the expression of our personal opinion only. In the first place, we feel that the Committee which drew this tentative report is entitled to the commendation and thanks of the country for what has been manifestly a work of tremendous labor and for the able and conservative report which they have presented. With

Jan 1, 1921

By C. Richard Tinsley, Norman Miskelly, S. James Hodge

Construction of the Ranger uranium project, located 230 kms east of Darwin in the Northern Territory, Australia, commenced in January 1979. Energy Resources of Australia Ltd (ERA) was incorporated in February 1980 to acquire all the rights in the project. The total cost to ERA of these rights was A$407 million, made up of A$125 million in cash to the Federal Government and the issue of 125 million A$1.00 shares at par, plus a payment of A$16 million in cash to each of Peko-Wallsend Ltd. (Peko) and EZ Industries Ltd. (EZ). ERA's cash requirements to complete the project were estimated in October 1980 to be A$553 million. Project loans, secured by first ranking debenture stock, were arranged for a total of US$390 million, while second-ranking debenture loans totalling A$60 million were [ ] obtained from the vendors, Peko and EZ. Overseas participants (power utilities who had agreed to purchase uranium yellowcake under contract) arranged to take up 25% of the equity capital for A$102.5 million; Peko and EZ were allotted 30.5% each as satisfaction of vendors' consideration; and 14% representing A$57.5 million was issued to Australian residents in an underwritten public flotation in November, 1980. The loan and equity financing arrangements required the successful resolution of many complex and interlocking factors, including technical and economic feasibility, agreement with Aboriginal interests, compliance with Government policies, and securing of sales contracts.

Jan 1, 1985

Jan 1, 1882

By A. S. Dwight

Taking up first the lead field, flotation concentrates offer serious difficulties in handling and in preparing for the blast furnace, quite aside from the problems presented to the furnaceman by the necessity of smelting smaller tonnages of material higher in grade and usually basic in character, with the consequent changes in flux requirements and furnace operation. As received at the smelter, these concentrates are always wet and usually of the consistency of sticky mud. Difficult enough to handle in warm weather, they are worse in winter, when it may be necessary to blast them out of the cars. They hang up in bins and chutes and stick to conveyors, requiring the constant attention of the operators. If dried they become like wheat flour, involving heavy dust losses in handling and in furnace operations. Roasting in hearth furnaces is more difficult than with coarser materials. Dust losses are increased and, what is more serious, the moist concentrates tend to form balls or nodules, which harden and pass almost unaltered through the furnace with consequent high sulfur in the product, while the unballed fine particles lie on the hearth in a dense bed, practically impenetrable to the oxidizing gases, so that roasting takes place only on the surface of the bed. A more prolonged roasting period is therefore required and the capacity of a given furnace is decreased. They are entirely too fine to be charged into the blast furnace, even if thoroughly roasted; excessive flue-dust losses, irregular operation and slowing up of the furnace would be the obvious result. Consequently, it was early recognized that flotation concentrates would have to be put in coarser condition for smelting and the universal method adopted has been the Dwight & Lloyd process of sintering. This did not usually

Jan 1, 1928

By E. A. Steigerwald, G. L. Hanna

The influence of work-hardening exponent on the variation of fracture toughness with material thickness was studied for high-strength steel, aluminum, and titanium alloys. The results indicate that, when materials are compared at similar fracture toughness to yield strength ratios, the material with the lower work-hardening exponent undergoes the transition from flat to slant fracture at a larger thickness than material with a high work-hardening exponent. In the thickness range where complete slant fracture is obtained the reverse is true and a lower work-hardening exponent results in a lower fracture toughness. The influence of work-hardening exponent on fracture toughness is, therefore, dependent on the particular fracture mode. In the transition region a low work-hardening exponent is beneficial for fracture toughness while in the 100 pct slant region it is detrimental. THROUGH the use of fracture mechanics analyses, the influence of geometric variables on the crack propagation resistance of structures can be interpreted with reasonable consistency. However, in order to gain a more complete understanding of the fracture process, the influence of material parameters on crack propagation must be defined and coupled to the macroscopic fracture mechanics approach. The work-hardening exponent, which characterizes specific material behavior, may serve as an effective parameter to allow some degree of coupling to be accomplished. In the extension of a crack in a specimen of suitable dimensions the propagation process occurs in a stable manner when the crack extension force is balanced by the resistance to crack extension, which exists in the material at the crack tip. As the applied stress, and therefore the crack extension force, on the specimen increases, the resistance also increases primarily because the effective plastic zone at the crack tip, which is the main energy absorption process, becomes larger. Since the work-hardening rate of a material influences the stress-strain relationship, it will also influence the energy absorption process in the plastic enclave at the crack tip and hence should have an effect on crack propagation. A number of studies have been made correlating the strain-hardening exponent or the strain to tensile instability with the ability of a material to resist fracture. Gensamer1 concluded that a low-strain-hardening exponent would result in a steep strain gradient at the base of a notch. He reasoned that a large work-hardening coefficient would result in high-energy ab- sorption due to the increased area under the stress-strain curve. Larson and Nunes2 experimentally observed in Charpy tests on steels heat-treated to below 200,000 psi yield strength that the energy to failure in the fibrous mode, i.e., above the brittle-to-ductile transition temperature, was logarithmically related to the strain-hardening exponent. In order to avoid the complicating effects present in studying materials which undergo a brittle-to-ductile transition, Ripling evaluated the notch sensitivity of a variety of fcc metals with varying work-hardening exponents.3 The results indicated that the relative notch sensitivity, as determined from tests on specimens with a sharp notch, decreased with increasing values of strain hardening. Although the energy required for ductile or fibrous fracture increases with increasing work hardening, high-strength steels often exhibit improved crack propagation resistance when heat-treated to obtain low values of strain hardening.4,5 An analysis of whether low strain hardening is beneficial or detrimental to crack propagation resistance must depend on the particular fracture criterion involved. At temperatures where the material is relatively ductile and the development of a critical strain is required for fracture, high strain hardening increases the energy required to produce failure. In the transition region and below, however, a critical stress law appears to be valid6 and a low rate of work hardening may produce superior resistance to semibrittle crack propagation. The experimental program is aimed at studying these possibilities and determining the specific influence of strain hardening on the crack propagation resistance of several high-strength materials. MATERIALS AND PROCEDURE The alloys, chosen as representative of various classes of high-strength materials, are summarized in Table I. The heat treatments evaluated along with the smooth tensile properties are presented in Table 11. Pin-loaded sheet tensile specimens were employed to determine the smooth tensile properties. A strain gage extensometer (measuring range 0.200 in.) was used at a strain rate of 0.02 in. per in. per min. The work-hardening exponents were determined from the stress-strain curves generated in the smooth tensile tests and the assumption that the portion of the stress-strain curve beyond the yield point can be described by the power relationship: where a is the true stress, P is the true plastic strain,

Jan 1, 1969

By P. H. Griffin

The manufacture of iron in the Province of Quebec forms one of the most interesting subjects in the development of this great industry in America. It began soon after the first steps taken in the New England colonies, where iron was first practically made in America. In both cases the ores smelted were bog-ores. In Qaebec the first work was done in and about, the town of Three Rivers, and many interesting facts in connection with the development of this industry may be found in the paper read at the Halifax meeting, September, 1885, by Mr. James Herbert Bartlett, of Montreal,* which traces the industry from its inception, about 1730, down to 1883, at which time the St. Maurice forge is declared to be the oldest active furnace on the American continent. A few years later the Canada Iron Furnace Company, Ltd., became interested in the enterprise, the extent of which has been greatly enlarged beyond all former limits. In fact, the manufacture of this particular class of iron has never been attempted on the scale now practiced by this company. This work has been carried on for the purpose of supplying a grade of iron hitherto procurable only at heavy cost for Canadian consumption from the United States, and for English consumption from Sweden. The manufacture of iron in the Province of Quebec was based entirely on bog-ores during the period referred to; and as the supply of iron made elsewhere from cheaper ores became more abundant, the local manufacture, handicapped by want of shipping facilities, lack of capital, and other natural causes, was gradually discontinued. It was always admitted that for certain purposes the iron made in the Province possessed special value; but the demand for articles requiring such special virtue was limited, and cheaper grades were gradually substituted for general uses. Some years ago we were led to test, in our car-wheel shops at

Jan 1, 1893

By R. W. Raymond

THE question, what is the best proportion among weight, fall, and speed of stamps, is one which has not yet received thorough and systematic examination. In considering the economical application of stamping machinery, we meet, at the beginning, with serious difficulties in obtaining accurate data for comparison. The weight and fall of stamps vary as the shoes and dies wear out; and this may lead to a change of speed also. Moreover, defects in engines, boilers, or machinery for the transmission of power, may occasion serious losses, which cannot fairly be charged to the arrangements of the stamps proper. Again, the capacity of stamp-mills is directly dependent, in some degree, upon the nature and extent of discharge, fineness of screens, and other peculiarities of the battery. Finally, the hardness and tenacity of the rock crushed varies so much that comparisons between different localities cannot be implicitly trusted. The safest experiments are those made in the same mill, by changing first one and then another condition of working; but this is seldom possible for such conditions as weight and lift of stamps, and only within narrow limits for their speed. We may eliminate questions of friction, transmission, and generation of power, in the case of stamps, by measuring the power actually developed by their fall. Thus, the weight, multiplied into the fall in feet, and the number of drops per minute, gives us exactly the number of foot-pounds exerted by each stamp. Dividing by 33,000, the number of foot-pounds per minute in one-horse power, we have the horse-power per stamp, from which the effective power of the whole mill may be obtained. Dividing the amount of rock crushed daily by the effective horse-power, gives us the daily amount per horse-power; and this is the best measure that can be obtained for the effectiveness of the stamps. A complete discussion of the subject would require us to determine the exact influence of the discharge, etc., and the exact resistance offered by different classes of rocks, for both of which points the data are wanting. Professor J. D. Hague, in the third volume of the United States Geological Exploration of the Fortieth Parallel, gives a valuable

Jan 1, 1873