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By H. R. Collins

The purpose of pulverizing coal before burning it is to make available every heat unit it contains. Machinery has been developed which will pulverize coal in one operation, delivering it to bins in front of the furnaces at an expenditure of about 17 hp.-hr. per ton, in a medium-sized plant. The cost of the operation depends upon the amount of moisture that must be expelled before pulverizing, the cost of labor, and the cost of coal delivered at the plant. At a small plant, requiring a pulverizer with a capacity of only 1/2 ton per hour, the cost per ton pulverized will naturally be greater than at a plant requiring the largest pulverizer, with a capacity of 7 tons per hour. :The first step is to reduce large lumps to a size suitable for drying uniformly, before passing to the pulverizing mills; this is done in rolls, at a single pass. The second step is the elimination of moisture, in order to facilitate pulverizing to great fineness, while also increasing the heating effect and the temperature attainable when the coal is burned. There are other mechanical advantages in the handling of dried coal. Driers are now manufactured which are able to eliminate moisture without distilling any of the volatile combustible matter in the coal; they are fired by hand or with pulverized fuel. The heat first surrounds the shell of the drier, being confined within a chamber where complete combustion takes place; the heated gases are then led through a duct to the discharge end of the drier and enter the inside of the shell at a temperature not exceeding 300" F. This temperature is maintained by the operator and is indicated by a pyrometer. Volatile combustible matter is not likely to be distilled until the temperature rises above 400" F. On discharging from the drier, the coal is usually passed over a magnetic separator in order to prevent pieces of iron from going to the pulverizer. Two types are used: a magnetic pulley which automatically discharges its collection of iron, and a lifting type, from which the iron is removed by hand when convenient. In the operation of pulverizing, the coal should preferably be reduced until 95 per cent. will pass through a 100-mesh and 70 per cent. through a 300-mesh sieve. Such a product is obviously an almost impalpable powder.

Jan 1, 1920

By J. Jordan, D. K. Denton, D. Tesarik, D. F. Scott, T. J. Williams

Personnel from the Spokane Research Laboratory of the National Institute for Occupational Safety and Health integrated the results of studies from a seismic tomographic survey, a finite-difference analysis, laboratory measurements of compression wave (ultrasonic) velocities in rock cores, and site geology to evaluate the use of seismic tomography for identifying induced pressures in an underground pillar at the Edgar Mine, Idaho Springs, CO. The key findings were that (1) the seismic tomograms showed that seismic velocities in rock adjacent to mine openings were low, (2) a difference tomogram in which in situ stresses on the east and west sides of the slot were compared showed that velocities increased west of the slot but decreased east of the slot, (3) geologic features (rock types and a fault) identified through geologic mapping were recognizable in the seismic tomograms, (4) ultrasonic velocity measurements on the rock cores agreed with seismic velocity measurements in the tomograms, and (5) results from a finite-difference analysis compared well to the seismic tomograms west of the slot but not east of the slot. The significance of this research is that seismic tomography is a useful tool for determining relative stress in underground pillars.

Jan 1, 2004

By Ingersoll Olmsted

Mr. D. H. BRowne's paper upon " The Distribution of Phosphorus in the Ludington Mine" (Trans., xvii., 616) has interested me very much, and perhaps I cannot give a better proof of that, interest than an account of my work and observations in the same direction while chemist of the Hudson River Ore and Iron Company. The ores of this company lie in a chain of low hills running northwest and southeast, about three miles back from the eastern bank of the Hudson river, below Hudson, N. Y. They occur in thick veins, with the characteristic Hudson river slate formation as hangingrock and foot-wall, and dip about 45' east, outcropping in many places near the top of the western slopes.

Jan 1, 1890

Gold recovered on the strikes at the Central Norseman mill, Norseman, Western Australia, has an approximate assay fineness of 850. Bullion recovered from the cyanide plant at the mine is of much lower value, and occasionally its assay fineness has been as low as 250. This indicates either that the fine gold particles in the ore consist of an alloy richer in silver than the coarse particles or else that a silver mineral, as well as the gold, is dissolved by the cyanide solutions.It had been observed at the mine that the amount of silver in the bullion appeared to increase when galena appeared to be more abundant in the stoped ore. Interest was, therefore, attached to the possible occurrence of a silver mineral associated with galena and, at the same time, soluble in cyanide.Four specimens of ore from different horizons in the mine were collected by the mine staff for examination as to whether any marked difference in the fineness of gold was apparent on a polished surface and for determination of the silver minerals. As the Norseman ore-body is a quartz reef containing a very small percentage of sulphide, the specimens were selected either because they cont;:lined free gold or because they were, relatively rich in sulphides. They were obtained from the following localities at the Phoenix shaft.1. Level 16, section 28.2. Level 16, section 31.3. Level 8, section 31.4. Level 14, section 38.Specimens Nos. 1 and 2 were thus obtained from different positions at the same mining horizon, while specimens Nos 2 and 3 were obtained from different levels in the same vertical section of the mine.All the specimens consist of quartz characterized by thin, discontinuous seams of sericite and the presence of a little ankerite. Gold and sulphides tend to be localized along these seams, but particles of gold and sulphides are also scattered throughout areas of white quartz. This scattered distribution of the sulphides in relatively wide areas of quartz has involved the preparation of two or more polished sections from each specimen.The outcome of the microscopical examination of these specimens has been to determine that there is no appreciable variation in the colour of the polished particles of gold and, therefore, no marked difference in the amount of silver alloyed with the coarse and fine particles. The presence of small quantities of the tellurides sylvanite, hessite and altaite has been revealed, and found to vary in abundance with the abundance of galena.

Jan 1, 1944

By I. Mc Dougall

"The matte/slag tidal zone in a platinum smelting furnace is subject to severe process conditions which can often lead to premature failure of the lining. The MgO-FeO-Si02 slag is aggressive to refractory bricks, whilst the Ni-Cu-Fe-S matte is aggressive to water-cooled copper cooling elements, and can penetrate and sulphidize refractory bricks, particularly at the high matte temperatures often experienced in the PGM industry. A novel approach to the lining design was taken at Lonmin's new 10MW Furnace 2. An indirectly-cooled graphite ring was applied in the matte/slag tidal zone, with refractory bricks on the hot face. Thermal Finite Element modeling was conducted to determine the optimal lining design in this region of the furnace. The resistance of two graphite grades to damage by slag and matte was evaluated experimentally. The graphite lining is not wet by the matte, and is resistant to slag attack at operating temperatures. In comparison to water-cooled copper in various configurations, cooled graphite shows promise as an indirect refractory cooling system in the tidal zone area of furnaces.IntroductionIn South African Platinum Group Metals (PGM) smelting operations, the PGMs are associated with nickel-copper sulphides in magmatic rocks. After ore is mined, it is concentrated by means of a flotation process prior to smelting. Both rectangular 6-in-line and circular 3 electrode AC submerged arc furnaces are used for this purpose. A new 10 MW round furnace is currently under construction by Tenova Pyromet at Lonmin's Marikana Smelter Division. An overview of Lonmin's smelting operations and Lonmin's approach to smelting high chromite containing PGM concentrates is given by Eksteen et al. [1]"

Jan 1, 2012

By J. W. Halley, G. L. Plimpton

BECAUSE of the two distinct stages in the solidification of rimmed steel, segregation in the rimmed ingot is more complex than that in the killed or semikilled ingot. In the earlier stage, chemical reactions, resulting in evolution of gas and vigorous stirring of the metal, effect a degree of negative segregation unique to rimmed steel. The composition of this zone constitutes the principal quality advantage of this type of steel. In the later stage of solidification, after the evolution of gas has ceased, the segregation follows the general pattern of a more completely deoxidized steel. However, the composition of the liquid remaining after the first solidification stage varies markedly from that of the original melt, some constituents having been partially removed as reaction products while the concentration of others has been intensified by rejection from the metal solidifying in the first zone. The aim, from the standpoint of segregation, in rimmed steel of high quality is to effect a maximum negative segregation in the rim zone without excessive concentration of undesirable elements at the center of the ingot. To achieve this aim, the composition of the melt may be varied and the furnace and pouring practice may be adjusted within certain limits. It is the purpose of this study to discuss segregation in rimmed steel from the standpoint of the mechanisms that produce it and to survey the phases of open-hearth practice that influence those mechanisms. MECHANISMS PRODUCING SEGREGATION The mechanisms that determine the degree of segregation in the rimmed ingot are closely interrelated, making it difficult to select the primary factors and to determine a satisfactory order for presenting them. For instance, the question of sulphur segregation is relatively simple, since sulphur is not directly involved in chemical reactions in the ingot; but its concentration in the rim zone is dependent not only on its original analysis in the melt, its segregation coefficient, and the freezing rate, but also on the rate of its removal from the impure film on the solidifying surface. This washing action involves all the factors (such as freezing rate, the carbon-oxygen product, pressure, etc.) that determine the rate of gas evolution and hence the efficiency of film removal. Sulphur distribution between the rim and core is affected by the volumetric ratio between the two zones, and its segregation in the core is a function not only of the freezing rate of the core but also of all the foregoing factors that determine its concentration in the metal when solidification of the core starts. To simplify the presentation, it is proposed to treat the mechanisms affecting segregation independently in this section, reserving a discussion of their over-all effects for the section in which actual segregation data are given. The factors affecting segregation will be treated in the following order: (I) differential solidification, (2) removal of constituents as

Jan 1, 1944

By R. F. Mehl, G. V. Smith

THE decomposition of austenite in steels, because of its immense practical importance, has been subjected to extensive study in recent years from the point of view of the mechanism of the process.1-3 Although much information has been acquired, a number of questions, principally of theoretical interest, remain. One is that of the atomic-crystallographic mechanism by which each of the various reaction products forms. The isothermal reaction products of the eutectoid decomposition in plain carbon steels (to which this study is restricted) have conveniently been classified in three general groupings-pearlite, bainite, and martensite. Of these several products, pearlite and martensite have been studied extensively, but bainite has received only scant attention. As a result, the mechanism of the formation of pearlite and that of martensite are now fairly well understood while a great deal of uncertainty exists regarding bainite. PEARLITE Pearlite forms from austenite by the precipitation of alternate platelets of cementite and ferrite, which grow into the austenite matrix .2-5 The rate of reaction may be described in terms of a rate of nucleation and a rate of growth.2.3 Mehl and Smith6 have attempted to determine the lattice relationships existing between the ferrite in pearlite and the parent austenite. Using a pole-figure method of analysis, it was found that a limited number of ferrite orientations resulted from the decomposition of a single grain of austenite; it was not possible, however, to decide between two assumed ideal relationships, both of which appeared to account for the experimentally determined pole figure. It was definitely shown, however, that the relationship obtaining was quite different from that determined for the proeutectoid separation of ferrite.7 No attempt was made to determine the habit plane (matrix plane to which the precipitate lies parallel) of the pearlite lamellae. Belaiew8 earlier had stated that the number of directions assumed by the pearlite lamellae in a single grain of austenite was 12 (no details were given) and concluded wrongly, as Mehl and Smiths have pointed out, that the lamellae delineate the [210] planes of ferrite.* MARTENSITE It is known that martensite is a transitional constituent of body-centered tetrag-

Jan 1, 1942

By A. R. Denison

The area discussed in this report comprises a group of 38 counties lying in the northeast corner of Texas. It covers all, and extends beyond, the borders of what is commonly described as the East Texas Basin. It includes two major oil fields, Van and East Texas; two major gas fields, Bethany and Waskom; and a number of fields, both oil and gas, of lesser importance. All commercial oil production comes from beds of Upper Cretaceous age and almost exclusively from the basal member, the Woodbine sand. Gas is produced from both Upper and Lower Cretaceous beds with the newer production from the older beds. East Texas Field This field continued as in 1932 and 1933 to dominate the drilling and production situation throughout the oil business. A total of 3681 producing wells was completed in this field during 1934. This is an increase of 1215 over the 2466 producers completed during 1933. Total wells

Jan 1, 1935

By B. K. Sternberg

Since 1986, we have developed a series of electromagnetic (EM) sounding systems at the Laboratory for Advanced Subsurface Imaging (LASI). These may be categorized by their frequency ranges: low frequency (LF, 30 Hz to 30 kHz), medium frequency (MF, 1 kHz to 1 MHz), and high frequency (HF, 30 kHz to 30 MHz). We have applied these EM systems to a variety of targets, including: mapping of plumes of contaminated groundwater, tracing leachate for an in-situ leaching operation, locating buried hazardous waste, identifying subsidence-prone zones and detecting buried voids. These systems are also applicable to exploration for ore bodies. Currently, our sounding system uses a vertical magnetic field vector. Previous systems of this type required a slow and relatively inaccurate manual rotation of the sensing coils. The systems also used occasional calibrations of the measuring system. We have developed a 3-dimensional mathematical rotation procedure for the data, as well as a simultaneous, high-accuracy, calibration method. These new developments have greatly increased the speed of the measurements, as well as improving the accuracy of the ellipticity data. We use stepped-frequency measurements along with narrow-band filtering to allow accurate measurements, even in high-noise areas. We typically obtain ellipticity measurements at eleven frequencies and along densely sampled profile lines. We use neural networks to help interpret the measured ellipticity patterns. Neural networks can be trained to relate the measured ellipticity patterns to earth resistivities or to discrete targets buried in the earth. The neural network training may use theoretical EM responses calculated from computer codes for relatively simple structures. The theoretical EM response for many complex targets that are of interest cannot currently be reliably calculated, even with the largest supercomputers available. We have therefore chosen to do some of the training using theoretical EM responses generated in a full-scale modeling tank located at our Avra Valley Geophysical Test Site. We have also developed data-visualization software to help interpret the large data sets produced by this system.

Jan 1, 1997

By R. F. Mehl, G. V. Smith

THE decomposition of austenite in steels, because of its immense practical importance, has been subjected to extensive study in recent years from the point of view of the mechanism of the process.1-3 Although much information has been acquired a number of questions, principally of theoretical interest, remain. One is that of the atomic-crystallographic mechanism by which each of the various reaction products forms. The isothermal reaction products of the eutectoid decomposition in plain carbon steels (to which this study is restricted) have conveniently been classified in three general groupings-pearlite, bainite, and martensite. Of these several products, pearlite and martensite have been studied extensively, but bainite has received only scant attention. As a result, the mechanism of the formation of pearlite and that of martensite are now fairly well understood while a great deal of uncertainty exists regarding bainite. PEARLITE Pearlite forms from austenite by the precipitation of alternate platelets of cementite and ferrite, which grow into the austenite matrix.2-5 The rate of reaction may be described in terms of a rate of nucleation and a rate of growth 2 3 Mehl and Smiths have attempted to determine the lattice relationships existing between the ferrite in pearlite and the parent austenite. Using a pole-figure method of analysis, it was found that a limited number of ferrite orientations resulted from the decomposition of a single grain of austenite; it was not possible,[ ]decide between two assumed ideal relationships, both of which appeared to account for the experimentally determined pole figure. It was definitely shown, however, that the relationship obtaining was quite different from that determined for the proeutectoid separation of ferrite.7 No attempt was made to determine the habit plane (matrix plane to which the precipitate lies parallel) of the pearlite lamellae. Belaiew8 earlier had stated that the number of directions assumed by the pearlite lamellae in a single grain of austenite was 12 (no details were given) and concluded wrongly, as Mehl and Smith' have pointed out, that the lamellae delineate the {210} planes of ferrite.* MARTENSITE It is known that martensite is a transitional constituent of body-centered tetrag-

Jan 1, 1942

By Eric D. Marks

Fatalities resulting from ground workers colliding with objects and construction equipment accounted for approximately 18% of the total construction fatalities experienced in 2010. Current injury and fatality measuring methods have proven to be inadequate due to their use of passive measures of safety rather than a more active approach, such as the use of leading indicator data (also called near misses) of hazardous proximity situations between ground workers and heavy equipment on construction sites. The objectives are to create and evaluate the effectiveness of a reliable algorithm for collecting and analyzing the resulting leading indicator data from hazardous proximity situations. Numerous experiments emulating typical interactions between workers-on-foot and heavy equipment are used to evaluate the proximity sensing and detection technology. Safety leading indicator data (also called near misses) generated by the proximity sensing and detection technology during the experimental trials are used to create and assess the resulting algorithm. Results from the experiments indicate that leading indicator data generated from these systems can be processed and analyzed to identify hazardous proximity situations and incidents on construction sites.

Aug 1, 2013

By H. Saridikmen, C. S. Kucukkaragoz

In the present study, the measurement of sulphur distribution ratios between the slag and metal phases encountered in the ferromanganese smelting has been carried out at 0.83 atm of partial pressure of CO at 1773 K by using classical gas-slag-metal equilibrium quenching technique as a function of composition. The distribution results were employed in calculating the sulphide capacities of SiO2-Al2O3-CaO-MgO-MnO slags in equilibrium with the Mn-Fe-Si-Csatd.-S metal phase. It is shown that the sulphur transfer from metal to slag phase increases with increasing the basicity of the slag. As expected, the sulphur distribution ratio decreases by increasing the silica content of the slag system. The effect of metal composition on the sulphide capacities of the slag as well as on the sulphur distribution ratios between the slag and metal phases have been discussed. Emprical relationships were developed to express the sulphur distribution ratios and sulphide capacities of the above slag system.

Jan 1, 2007

The income of the Institute is derived from dues, subscriptions to MINING AND METALLURGY and sale of publications. These sources are fortunately supplemented by the interest from invested funds now amounting to over $500,000, a considerable portion constituting endowments for especial purposes. Aside from the medal funds the principal endowments are the James Douglas Fund for support of the Library, the Rocky Mountain Fund and the Seeley W. Mudd M.emoria1 Fund. The income from the two last named is available for the support of research and a variety of other purposes. It is allocated by the Board of Directors upon recommendation of standing committees in each case. An active effort is being made to increase the endowments of the Institute, it being felt that unusual opportunities exist for research and public and professional service through the organization and at a minimum of expense.

Jan 1, 1932

By D. G. Bishop

This paper is intended as a review and update of the use of Pressure Injected Footings as deep foundation units in North America. We will discuss various aspects of this pile and then discuss a particular project - the Mobile Alabama Convention Centre which is currently under construction. Pressure Injected Footing is a generic name used to describe a foundation unit that has been in use around the world for some 80 years. It has been used on all types of structures. It is an excellent pile in both compression and tension. It is particularly economic where a layer of granular soils can be found at relatively shallow depths. Other types of piles would penetrate these layers. Caissons are often difficult to construct in these soils because of their lack of cohesion and the often present water table. PIFs can density these shallow layers and carry relatively heavy building loads on them.

Jan 1, 1992

By Xun Luo

In this paper we report on the use of microseismic monitoring techniques to investigate the fracturing process associated with longwall mining. The study was carried out at three mines in Australia and concentrated on some major concerns of the mines, such as failure patterns and growth rate associated with mining progress, their implications to water ingress and gas emissions, caving processes in the goaf and precursors of roof falls. The results have shown that a zone of shear fracturing has occurred further ahead of the longwall face than predicted using conventional longwall geomechanics theory. Failure patterns in the roof and floor vary from mine to mine and this appears to be dominated by geological structures. The reaction of faults, the formation of fractures which allow gas emissions and precursors roof falls have also observed. Results from this work have opened up new understanding of longwall caving processes and proved that microseismic monitoring is a very useful technique for studies of longwall geomechanics and hazard controls.

Jan 1, 1998

By M. W. Franklin, D. W. Hendriks

"Changing ore types, feed grades and c1rculat1ng loads are some of the many factors that can make flotation feed-back control difficult. To control a flotation circuit using conventional fixed-parameter control algorithms, one must either tune the controllers very often or tune the controllers to the middle of the normal operating range. The former approach is very time consuming, while the latter approach can lead to long periods of either very sluggish responses or highly reactive responses which can lead to instability. The problem becomes compounded if feed-forward variables are introduced, creating even more variables to tune. An alternative to a fixed-parameter control algorithm is an adaptive control algorithm. An adaptive control algorithm continuously retunes itself based on previous reactions to its changes. Feed-forward control also becomes much more viable because the algorithm will tune the feed-forward parameters and the feed-back parameters simultaneously. Using the combination of feed-forward and feed-back tuning is an effective way to decouple the loops needed in flotation circuits where one circuit feeds into another. The advantages of adaptive controllers over conventional controllers will be introduced through the use of a simulator. Also discussed will the be the implementation of adaptive controllers at Brunswick Mining and some of the modifications that are available to help solve more difficult control problems.Brunswick Mining is located just outside of Bathurst, New Brunswick. The concentrator processes approximately 10250 tonnes per day of ore that assays at approximately 8.9 %zn, 3.6 %Pb, 0.3 r.cu and I 00 gram/tonne of Ag. The four products produced are zinc concentrate assaying 51 %Zn, lead concentrate assaying 34 %Pb, copper concentrate assaying 21 %Cu, and a bulk concentrate assaying 32 %Zn and 18 %Pb."

Jan 1, 1986

By J. Linhart

In vertical airways, falling material - solids-or water - may cause undesirable disturbances in the ventilation in the airway itself and also in neig¬bouring airways unless precautions are taken to stabilize the air flow. Such cases can occur, for example, - in shaft sinking by drilling from a pilot hole, - during the filling up of shafts, and - during the introduction of water into shafts in the case of mine fires. In an airway with upward ventilation the falling material will reduce the air flow and may even re¬verse its direction. In an airway with downward ventilation the air flow can only increase, but a reversal of the direction of ventilation may result in a parallel airway. These disturbances in the normal ventilation are undesirable as it must be the aim to have ventilation that is stable in quantity and direction throughout a mine. In order to be able to prepare suitable stabilization measures one must know the pressure generated by the falling material; this pressure will henceforth be called "aeromotive" pressure. The main factors determining the influence of falling material on the ventilation are - the amount of falling material and its height of fall, - the cross sectional area of the airway, - the pressure. difference prevailing in it, - the-position of the. airway in the ventilation. network, - the air velocity, and - other parameters, e. g. the density and grain size of the falling material. To determine the aeromotive pressure-measurements have been made underground during the sinking and filling of shafts and systematic studies have been carried out during the supply of water into a staple shaft. The present paper deals first with some fundamental theoretical considerations and then describes the measuring arrangements and the results of the series of experiments that have been carried out.

Jan 1, 1980

By Peter Shuttleworth, Chris Fesq, Eddie Woods

Precast concrete segmental linings for tunnels have traditionally been designed with conventional steel bar reinforcement. In many cases, this has been satisfactory in service, but in others, major problems have occurred with the durability of the linings. Commonly this has resulted from corrosion of the reinforcement, mainly from chloridesin ground water, causing spalling of the concrete and leading to very expensive and disruptive repair programs. This paper discusses the relative merits of designing tunnel linings with steel fiber reinforcement to provide long-term durability, improved impact resistance and toughness for greater load capacity across joints, enhanced robustness during transportation and erection, plus improved fire resistance with the addition of polypropylene fibers. Guidance is also given in the selection of the correct fiber type, mix design and testing methods to establish the optimum dosage required and production techniques to ensure even distribution and compaction.

Jan 1, 2005

The Olympic Dam Project constitutes a major resource of Copper and Uranium and has been under intensive evaluation since the discovery in 1975.A 500 metre deep rectangular shaft has been sunk into the deposit and this has been followed by 8400 metres of level, incline and decline development. 5 surface ventilation raises have also been constructed.Large scale trackless equipment is used to carry out the development, and productivity statistics are given.The paper describes the functionalised system used in the development program and discusses the maintenance support, and services required to carry out these works.The objectives of the Exploration Development program and the satisfactory results obtained from this work are also discussed.

Jan 1, 1985

By Leo F. Reinartz

It was with humility that I accepted the invitation of the Board of Directors of our Institute to deliver the Twentieth Howe Memorial Lecture. Many previous lecturers could speak from personal experience of the great work done by Professor Howe. It was not my privilege to be one of his students but, indirectly, I came under the influence of his work many years ago. My mentor in Metallurgy at Carnegie Institute of Technology, Prof. Fred Crab tree, was an ardent admirer of Professor Howe and his work. Professor Crabtree taught me early to appreciate Professor Howe's love of truth and keen desire to find a scientific reason for every metallurgical phenomenon. In this early search, Professor Howe encountered many unexplainable facts. Nevertheless, in the classic text, "The Metallurgy of Steel," published in 1891, he indicated that he believed Research could light the way. Under the heading of "The Treachery of Steel" he said: "In the early use of Bessemer and Open Hearth Steel, many then unexplained and hence mysterious failures occurred. With our present knowledge, an easy explanation of most of them would probably have been seen. But even today certain unexplained and apparently inexpli- cable failures occur in steel; inexplicable in spite of full and intelligent investigation." Then Professor Howe continued to talk about "the trustworthiness of steel" in the following manner: First, the steel-maker has learned by experience. He knows today far better the effects of a high percentage of carbon or of phosphorus; of cracks, pipes and blow-holes; of segregation and imperfect mixing; of over-heating; of finishing too hot or too cold. Knowing, he guards against them more effectually, and keeps at home much steel that he would formerly have sent into the market. Those who would not, or could not learn and do, have been driven out of the business; the conditions necessary for producing good sound steel by the acid Bessemer and the acid Open Hearth processes have been mastered. By and by, the basic process came along with new conditions, new liabilities to unsoundness, a great hue and cry about mysterious fractures followed, and Lloyd's register provisionally forbade the use of basic steel. Much basic steel was irregular and brittle throughout; too much carbon, too much phosphorus, too cold teemings—imperfect mixing. Still there was little doubt that, with further experience, these difficulties of the basic process would be mastered as those of the acid process had been. This shows that Professor Howe could not take anything for granted. Believing that careful research would find the answer to all mysterious phenomena, he was several generations ahead of the practical acceptance and adoption of this principle.

Jan 1, 1943