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By G. H. Wilson

INTRODUCED in 1946 to serve a need in power- plant operation, closed-circuit TV has been used by well over 200 organizations in approximately 25 different industries. Known as industrial television, or simply ITV, it can be described as a private system wherein the television signal is restricted in distribution, usually by confinement within co-axial cable that directly connects the TV camera to one or several monitors, Figs. 1, 2. The picture is continuous and transmission is instantaneous, permit- ting an observer to see an operation that may be too distant, too inaccessible, or too dangerous to be viewed directly. Destructive testing or the machining of high explosives can now be conducted hundreds of feet away by personnel who still have close control through the eyes of the TV camera. It is also possible for one man to control operations formerly requiring the co-ordinated efforts of several workers. For example, at a large midwestern cement plant conveyance of limestone from primary crusher to raw mill and loading into five storage bins once necessitated the work of two men, one having little to do but prevent spilling of material by manually moving the tripper on the belt conveyor as occasion required. TV cameras mounted on the tripper now provide bin level indication to the conveyor operator at the crusher position so he is able to control the entire loading operation remotely, Fig. 3. By means of a switch, the picture from either camera is alternately available on a single viewer, or monitor, Fig. 4. Each camera is mounted on the tripper by means of a simple adjustable support and looks down into the bin, which is identified by the number of cross members on the vertical rod. Each associated power unit is located on a platform above the camera, Fig. 5. This centralized control by means of TV often has produced superior results, and in many instancés saving in operating costs has been sufficient to write off equipment costs within six months to a year.

Jan 7, 1954

By B. Woyski

Many writers, in discussing defects caused by oxidation and gassing of bronzes and red brasses advocate substantially the same cure for both. But from its nature, oxidation cannot take place if there is an excess of fuel in the furnace, while the gases absorbed by some alloys are products of incomplete combustion of the fuel. Hence the metal can be either oxidized or gassed, but it is doubtful whether these actions can take place simultaneously. Oxidation can be easily overcome by the use of deosidizers or it may be avoided by protecting the molten metal with suitable fluxes. Absorption of gascs is more difficult to overcome: the regulation of the air and fuel, so as to produce complete combustion, and the protection of the bath by mineral fluxes arc the most important factors. Gas expulsion, resulting in gas holes, porosity, unsoundness, and swollen or cauliflower-headed risers, is said to have several causes. One writer1 lists the most common causes in the order of their importance, as follows: Superheated metal, dirty or slaggy furnace conditions, using metals low in quality or those previously subjected to bad melting practice, poor grade of fuel, use of newly lined or damp ladles, indiscriminate mixing of scrap or illogical combinations of metal. Superheating the metal usually occurs when the heat is ready to be poured but for some reason must be held in the furnace. In this case, a careful furnace tender tries to avoid overheating the metal by keeping a mild fire; that is, a reducing fire which, unfortunately, results in gassing the metal. A dirty, slaggy furnace may result in gassing the metal by retarding the heating and prolonging the time necessary to bring the metal to the proper temperature, thereby increasing the chances of gassing in uncertain furnace atmosphere. It is doubtful whether rnetals of low quality have anything to do with gassing molten metal, except, possibly in the case of metals containing

Jan 1, 1923

By N. Lilienberg

Refractory materials play much the same part in the producion of metals as houses and shelter for men, and it therefore seems useful to discuss sometimes the ways of manufacturing them. In fact, it appears to me that too little has been said on this important matter, probably because the manufacturers of fire-brick do not care to publish details for the benefit of competitors, but perhaps, also, by reason of the indulgent indifference of consumers. Judging from the revolutions in the manafacture of iron and steel caused by using calcareous materials for the furnace-bottoms, it does not seem improbable that in the future basic bricks may be produced suffciently strong for building also side-walls and arches, and perhaps, also, for use in blast-furnaces. But the existence of the present difficulties of great shrinkage in burning and small strength against compression, which limit the possibility of using basic bricks to Bessemer converters and such open-hearth furnaces as permit the bottom to be separated from the superstructure, seems to indicate still a long and extensive use of silica fire-bricks. I am not prepared to say anything about American fire-brick making, but knowing that industries abroad are watched with increasing interest by American manufacturers, I have imagined that this association would like to hear some facts about the way firebricks arc made in my country—Sweden. Well-known as it is that Sweden produces a high quality of iron, it is perhaps not so universally known that the same country produces a very high grade of silica fire-brick, whereby most of its own wants are supplied. In giving the following sketch I can, of course, not claim that all the facts are entirely new, but shall consider my object attained if American manufacturers can derive some benefit from the comparison of the following methods with their own, and if some discussion on this important subject can be aroused which will contribute to further progress. In order to show the extensive use of domestic fire-bricks in Sweden, where English bricks are easily obtainable, I mention the fact that about twelve millions of all kinds of fire-bricks (reduced to

Jan 1, 1885

By Gustav Egloff

THE treatment of emulsified crude oils has been a problem for years in the petroleum industry. Until comparatively recently various methods of settling with and without chemicals have been used with indifferent success. Since wells have been acidized, emulsified crudes have been produced, which acid considerably to the need for improved methods of treatment. The presence of large quantities of salts in the oils from acid-ized wells has presented several new problems to the industry. The use of hydrochloric acid in well treatments has caused the formation of sodium, magnesium, and calcium chlorides by interaction with the dolomitic limestones. These salts dissolve readily in the water normally present in the oil, and they are therefore incorporated in the emulsified oil. The crystalline salts have also been found in the oil, prevented from settling by protective films such as asphalt, resins and petrolatum. In, some instances, free hydrochloric acid has been found. The salts may be present in crude oil in amounts ranging from a few pounds to over 1000 lb. per 1000 bbl. of oil. The transportation of these crude oils through pipe lines has led to erosive and corrosive effects, which are a tremendous cost to the petroleum industry. During 1937, more than 1,200,000,000 bbl. of crude oil was transported through pipe lines. Of this quantity approximately 10,000,000 bbl. was water, and considerably more than 50,000,000 lb. was salts. If the crude oils were treated at the producing wells to remove the salts and water, an appreciable saving would be possible. The treatment would not be difficult, since it has been found that these oils are more easily treated at the time they are produced than after the aging and more stable emulsification that occur before they reach the refinery. Since great costs are involved in the use of these salty crudes at the refinery, treated oils essentially free of salts would naturally command a premium.

Jan 1, 1938

By AIME AIME

THE session on milling methods on Monday afternoon.* with G. H. Clevenger, chairman of the Mining Methods Committee presiding, was well attended. However, none of the authors of the papers presented were present except Messrs. Taggart and Ince. The paper on "Elements of Operations of the Pneu¬matic Table," by Messrs. Taggart and. Lechmere-Oertel, was presented by Professor Taggart as was the paper on "Calculations in Ore Dressing," by Luyken and Bierbrauer, due to the absence of the authors.

Jan 1, 1929

By A. T. Beckwith

THE Lehigh Navigation Coal Company Inc. operates steep-pitch, relatively deep mines in the Panther Creek Valley, at the eastern end of the southern anthracite coal field. Commercially minable coal beds are the Mammoth,† Primrose, Orchard, and Buck Mountain,‡ their respective thicknesses average 50, 15, 1o and 12 ft. Sand slates immediately overlie and underlie these beds, though in some locations sandstone or conglomerate beds occur. Underground operations extend to a depth of 1200 ft. below the surface, and comprise a bulk of virgin work on the lower levels, and a small amount of remining on the upper levels. With increase in depth, ventilation has become a more important factor. DEVELOPMENT In early days slopes or drifts were driven in the outcropping coal on the hillsides. Subsequent development was by water-level tunnels, with portals above high water in Panther Creek. These tunnels have been maintained because they intercept and drain much water that enters the mined-out portion of the bed and otherwise would follow down to the deep workings. Below these tunnels, the coal was customarily developed by slopes. Muleways, which are zigzag chutes easy to travel, were also driven to connect lower openings with the water levels. When it became necessary to go still deeper, the slopes were abandoned, and vertical multicompartment shafts were sunk from the surface. Levels have been at vertical intervals of from 195 to 250 ft. Recent practice has been toward the latter spacing; splitting the total lift, however, by starting to mine from chutes extending halfway up to the level above. Chutes customarily are spaced at 50, 60 or 70-ft. centers along the gangways. At some mines, additional shafts have been sunk from the surface to the level containing the main pumping station, and these carry the discharge lines from the pumps. As the mines are ventilated by the exhausting system, both the hoisting and so-called water shafts serve as intakes. The main fan is always on the surface, and is connected with the return airways from the various levels by an air hole or a vertical shaft. For economy, when the present deepest levels were developed, main return-air shafts or air holes were not extended to the new level, but connections were made from the new level to that above by two or more holes. It is doubtful that this method will be continued, as complications in the system, increased resistance to flow, and other difficulties undoubtedly will counterbalance any economies this provision may afford.

Jan 1, 1942

By Paul A. Schafer

BALATOC mine, the principal gold-producing mine in the Philippines, is 10 miles southeast of Baguio, in the Cordillera Central of northern Luzon.1 The region is a deeply dissected plateau, ranging in altitude from 3000 t0 5000 ft. above sea level. The rocks consist chiefly of granodiorite, diorite, and remnants of metamorphosed sediments, cut by dikes of andesite porphyry and quartz-diorite porphyry. All are intruded by a volcanic breccia plug, oval in horizontal section, about 3200 ft. long and 2300 ft. wide, which is the north central part of the mineralized area. Three main vein systems have been developed (Fig. 1): q6, 231 and 364, which strike about N.70°E. and dip 5o to 90°S. Each system is a braided zone consisting of many individual components. They are disturbed by a series of premineral faults or shear zones striking about N.45°E. Twelve of these produce important effects on the persistence, character, and quality of veins. From west to east the faults are named (after claims): Hog, Big Gun, Bull, Pine, Lolita, Bar No. I, Bar No. 2, Curt, Sun, Helen, Itoe, and Frog. They are early breaks formed prior to the N.70°E. vein fractures. Mineralization occurs on them but, with several prominent exceptions, they are too low grade to mine. A number of northwesterly striking faults complete the structural pattern. Although they are relatively abundant, the effect on the veins is so small that they do not present any problems in mining or development. All of these faults that have been observed are later than the N.70°E. veins and offset them to the left. NORTHEAST FAULTS The early northeast faults* are notably continuous in spite of their small displacements, 20 to 100 ft. Frequently they appear so weak that their importance is masked and their identity clouded. The gouge along any of these faults may vary from exceedingly weak at one point to very strong at another point only a short distance away. In other words, the amount of gouge depends on the changes of attitude of the fault plane, and is no indication of the extent of the movement. Places where walls are spread apart are filled with gouge squeezed from tight places. Also, mineralization sometimes obscures fault gouges by replacement. The mineralization of northeast faults has produced several important ore bodies; namely, 231 west on Pine fault and q6 vein on the same fault. To a smaller extent, Lolita, Curt, Bull, Bar No. I, and Sun

Jan 1, 1942

By L. E. Wilsey, W. G. Bearden

This paper presents results of analysis of the effect of fracturing on initial flow rates and on ultimate recoveries from low capacity oil formations. This analysis shows that even in formations of permeability as low as 0.1 md, large fracture treatments can yield oil recoveries and production rates approaching those of high permeability formations. Field production information is shown which supports the analytical work. INTRODUCTION Often hydrocarbon bearing formations are discovered which, while they are known to contain large quantities of oil, will not produce at commercially attractive rates without special well stimulation. Attempts to solve this problem led to the development of such techniques as underreaming, shooting, acidizing, and recently hydraulic fracturing. These methods of stimulation have been highly successful in many fields. All of these treatments, however, affect only the pay section near the well bore and therefore owe their success to circumventing and overcoming local permeability reduction about the well bore. It has been the belief that in treating wells to stimulate production in which there is no permeability reduction near the well, the maximum possible production rate increase would be of the order of two or fourfold. Hence, it has been concluded that fracture treatment of uniformly low capacity (permeability times thickness) formations could meet with but limited success. It is the purpose of this paper to show that the use of fracture treatments much larger than usually used can yield commercially attractive producing rates and high recoveries even in formations of permeability less than 0.1 of a md. PROCEDURE In order to illustrate the effects of fracturing, an analytical study of some hypothetical systems was made in which one factor at a time was varied to show what is important in recovering oil from fractured wells. It was assumed that a horizontal fracture of relatively high fluid-carrying capacity extended from a well bore. The presence of such a fracture will cause a marked influence on the flow pattern and pressure distribution in the formations, with the net effect being to reduce tremendously the resistance to flow into the well bore. A diagram of the resulting flow pattern and pressure distribution is illustrated in Fig. 1. Immediately after production commences, the principal flow of fluid is vertically from the formation flanking the fracture, into the fracture, and then into the well. After sufficient oil and gas have been produced to lower the pressure in the formation adjacent the fracture, oil and gas will begin to flow in a radial manner into the fracture from the formations beyond the end of the fracture. In calculating the performance under such conditions. the material balance or conservation of matter equation and equations of flow were solved simultaneously by a stepwise method of calculation. Flow rates were found by determining the pressure distribution, as illustrated

Jan 1, 1955

By Don M. Jackson

The techniques for the growth and controlled, graded doping of silicon epitaxial overgrowth layers were established. Grading of- impurities such as arsenic or boron in arbitrarily chosen profiles oiler four orders of magnitude (from I X 10Lg to 1 X 10L5 cm) was accomplished. The graded structures were grown in a stepwise manner where in the profiles were approximated by growing many separate layers with small doping-level changes between layers. Masked-area growth of silicon through windows in a SiO2 masking film was acconiplished through the simultaneous injection of HCl gas 102th Sic14 in the epitaxial reactor. The HCl served to inhihit the growth of silicon on the Sz02 surface, and also to control the cross-sectional profile of the silicon mesas. silicon from the substrate was etched out through the windows, and then epitaxial material was used to fill the holes hack in to form planar diodes. Simullaneous HCl injection was adapted to control the cross-section profile of the hack-filled regions. Arsenic-huried regions beneath in te- In recent months, the epitaxial growth process in semiconductor materials technology has evolved into a complex system directed at both material improvement for better monolithic integrated-circuit characteristics and the development of new silicon structures for future integrated-circuit needs. The advent of high-temperature HC1 gas etching1 grated-circuit transistors reduced V(SAT) by slightly more than one third, bringing this parame-ter to that of an isolated component transistor. When arsenic was diffused into the starting sub-stvate, it was necessary to remove any excess arsenic in order to avoid excessive audodoping of the subsequent epitaxial layer. Oxide isolation of single-crystal regions in a substrate provided complete electrical isolation of integrated-circuit components, thereby eliminating parasitic capacitance which is inherent in standard integrated-circuit processing. The process involved the etching of deep mesas on silicon Wafers, the formation of an oxide over the mesa surface, and then the deposition of several mils of polycrystalline silicon over the oxide. The original substrate was lapped and polished allay until the mesas were left isolated in the polycrys-talline matrix. The Final components were fabri-cated in the single-crystal islands. Speed and power-handling capabilities of standard circuits were improved through the process. wherein work-damaged material is removed from the surface of the silicon wafer just prior to the silicon deposition step has made it possible to grow silicon films with structural quality that approaches that of the substrate. HBr used in the same volume ratio as HC1 etches silicon at the same rate and with the same results as HC1. Recent developments in epitaxial materials technology have occurred in the areas of precise doping control, buried prediffused regions between over-

Jan 1, 1965

By B. W. Frazer

In the numbers of the Engineering and Mining Journal of June 27th and July llth, 1874, there appeared some very complete statistics of the working of some anthracite blast-furnaces belonging to a large establishment in this country, followed by calculations of the heat requirements of the furnaces, similar to those which have been made for European furnaces by Mr. I. Lowthian Bell, Prof. Gruner, Prof. Akerman and others. To the author of these valuable papers, Mr. John A. Church, of New York, the thanks of American iron metallurgists are due for this attempt (the first, to my knowledge at least), to attack systematically and scientifically the problem of economy of fuel in our anthracite blast-furnaces, by applying the formulas obtained from European practice and from the experiments of European metallurgists, to the determination of the amounts and the modes of distribution of the heat production and absorption in our furnaces. In order to facilitate a comparison of the results thus obtained for the anthracite furnaces in question with those obtained for the best types of European coke furnaces, I have reduced 60 the same standad of heat units (the product of the ton and the degree Centigrade), and placed side by side, the calculations of the heat requirements of one of the furnaces of the Clarence works, as given by Mr. Bell, of a furnace at Pouzin, on the banks of the Rhone, given by Prof. Gruner, and of the anthracite furnaces for 1869-73, as given by Mr. Church. Table I shows the different conditions of working of the three furnaces, of which Table II gives the respective heat requirements. I have made this latter table in such a manner as to give for each furnace its heat requirements, both according to the views of Mr. Bell and those of Prof. Gruner. Mr. Bell assumes that all the carbonic acid produced by the decomposition of the carbonate of lime of the charge, is reduced to carbonic oxide by contact with solid carbon ; also, that the carbon of t,he pig iron is a portion of that deposited in the ore in the upper part of the furnace, by the dissociation of carbonic oxide. Prof. Gruner, on the other hand, assumes that all the carbonic acid of the carbonates of the charge escapes unreduced, and that the carbon deposited in the upper part. of the furnace, by the dissociation of carbonic oxide, is again converted into carbonic oxide or

By M. Gensamer, B. Lustman

A recent paper described, by means of stereographic pole figures, the preferred orientations produced by cold-rolling low-carbon steel of automobile-body grade. It was found that the surface of the sheet exhibited a deformation texture significantly different from the texture possessed by the inside of the sheet. Efforts to produce the surface texture by buffing a sample exhibiting the normal or inside texture, using a copper lap, have not been successful. In view of the data collected by Kurdjumow and Sachs2, it was suggested that the surface texture might be the result of partial recrystallization of the normal or inside texture. The recrystallization texture of cold-rolled mild steel was studied by Goss3, but he did not use the pole-figure method, so that his conclusions were in need of verification. For these reasons the work reported in here was undertaken. It had two objectives: (1) to study the general behavior of cold-rolled mild steel on recrystallization below the critical temperature Al, and (2) to attempt experimentally a demonstaration of the genesis suggested above for the surface texture in cold-rolled steel. The material was that used by Gensamer and Mehl, cold-rolled to 97.5 per cent reduction in thickness. Fig. 1 is an X-ray pinhole photo-gram of this material, taken with the beam transmitted perpendicular to the plane of the sheet, using a molybdenum target at 35 kv. with no filter. It is typical of the inside texture, but in it the deformation texture is better developed than in the samples that showed a well developed difference between the inside and surface samples. Specimens from this sheet, which was 0.005 in. thick, were annealed for 5 min. at various temperatures in a lead bath. After about 0.0005 in. had been etched from both surfaces, X-ray photograms were prepared, using the technique described in the earlier paper1. Figs. 2 to 6 are photograms of the annealed sheet, at 566, 571, 577, 580 and 650" C. (1050' to 1202" F.), in order. Fig. 2 shows that 5 min.

Jan 1, 1937

By George M. Fowler, F. E. Gregory, William M. Agar, Joseph P. Lyden

The fact that most of the zinc-lead ores of the Tri-State district are associated with abundant chert in the Boone formation has led us to give much consideration to the manner of occurrence of the chert throughout the formation and to its relationship to the structural and other geologic features having bearing upon the sulfide mineralization. Necessarily the question of the source and the manner of deposition of the chert has come up in the course of these studies. We do not pretend to have arrived at the answer to all the questions regarding the chert. However, we have made a very large number of field observations, which present certain facts about the chert in this district that may be worth elaboration. Whatever theories may be drawn upon to explain the presence and distribution of the chert must necessarily be capable of reconciliation to these facts. The more important theories that have been presented are briefly summarized, and some of them discussed, in this paper. This paper is in three distinct parts, each complete in itself, wherein is recorded the evidence gained from three separate methods of attack. In an earlier paper,(3)‡ we briefly described the chert and its relation-ship to the ore deposits. Chertification, as used in this paper, means the replacement of limestone by introduced silicic acid. It is a common phenomenon in many widely distributed limestones. The products of chertification may be chert, cotton rock, or tripoli, depending upon the extent to which the replacement has been carried. Chertification is used instead of silicifica-tion in order to reserve the latter for the siliceous emanations so common in connection with the sulfide ore deposits of this and many other districts. Broadly, it is meant to include all silicification in this district prior to the introduction of the jasperoid, the latter being contemporaneous with the ore-bearing solutions.

Jan 1, 1935

By William M. Agar, F. E. Gregory, Joseph P. Lyden, George M. Fowler

The fact that most of the zinc-lead ores of the Tri-State district are associated with abundant chert in the Boone formation has led us to give much consideration to the manner of occurrence of the chert throughout the formation and to its relationship to the structural and other geologic features having bearing upon the sulfide mineralization. Necessarily the question of the source and the manner of deposition of the chert has come up in the course of these studies. We do not pretend to have arrived at the answer to all the questions regarding the chert. However, we have made a very large number of field observations, which present certain facts about the chert in this district that may be worth elaboration. Whatever theories may be drawn upon to explain the presence and distribution of the chert must necessarily be capable of reconciliation to these facts. The more important theories that have been presented are briefly summarized, and some of them discussed, in this paper. This paper is in three distinct parts, each complete in itself, wherein is recorded the evidence gained from three separate methods of attack. In an earlier paper,(3)‡ we briefly described the chert and its relation-ship to the ore deposits. Chertification, as used in this paper, means the replacement of limestone by introduced silicic acid. It is a common phenomenon in many widely distributed limestones. The products of chertification may be chert, cotton rock, or tripoli, depending upon the extent to which the replacement has been carried. Chertification is used instead of silicifica-tion in order to reserve the latter for the siliceous emanations so common in connection with the sulfide ore deposits of this and many other districts. Broadly, it is meant to include all silicification in this district prior to the introduction of the jasperoid, the latter being contemporaneous with the ore-bearing solutions.

Jan 1, 1935

The fact that most of the zinc-lead ores of the Tri-State district are associated with abundant chert in the Boone formation has led us to give much consideration to the manner of occurrence of the chert throughout the formation and to its relationship to the structural and other geologic features having bearing upon the sulfide mineralization. Necessarily the question of the source and the manner of deposition of the chert has come up in the course of these studies. We do not pretend to have arrived at the answer to all the questions regarding the chert. However, we have made a very large number of field observations, which present certain facts about the chert in this district that may be worth elaboration. Whatever theories may be drawn upon to explain the presence and distribution of the chert must necessarily be capable of reconciliation to these facts. The more important theories that have been presented are briefly summarized, and some of them discussed, in this paper. This paper is in three distinct parts, each complete in itself, wherein is recorded the evidence gained from three separate methods of attack. In an earlier paper,(3)‡ we briefly described the chert and its relation-ship to the ore deposits. Chertification, as used in this paper, means the replacement of limestone by introduced silicic acid. It is a common phenomenon in many widely distributed limestones. The products of chertification may be chert, cotton rock, or tripoli, depending upon the extent to which the replacement has been carried. Chertification is used instead of silicifica-tion in order to reserve the latter for the siliceous emanations so common in connection with the sulfide ore deposits of this and many other districts. Broadly, it is meant to include all silicification in this district prior to the introduction of the jasperoid, the latter being contemporaneous with the ore-bearing solutions.

Jan 1, 1935

By F. E. Gregory, George M. Fowler, William M. Agar, Joseph P. Lyden

The fact that most of the zinc-lead ores of the Tri-State district are associated with abundant chert in the Boone formation has led us to give much consideration to the manner of occurrence of the chert throughout the formation and to its relationship to the structural and other geologic features having bearing upon the sulfide mineralization. Necessarily the question of the source and the manner of deposition of the chert has come up in the course of these studies. We do not pretend to have arrived at the answer to all the questions regarding the chert. However, we have made a very large number of field observations, which present certain facts about the chert in this district that may be worth elaboration. Whatever theories may be drawn upon to explain the presence and distribution of the chert must necessarily be capable of reconciliation to these facts. The more important theories that have been presented are briefly summarized, and some of them discussed, in this paper. This paper is in three distinct parts, each complete in itself, wherein is recorded the evidence gained from three separate methods of attack. In an earlier paper,(3)‡ we briefly described the chert and its relation-ship to the ore deposits. Chertification, as used in this paper, means the replacement of limestone by introduced silicic acid. It is a common phenomenon in many widely distributed limestones. The products of chertification may be chert, cotton rock, or tripoli, depending upon the extent to which the replacement has been carried. Chertification is used instead of silicifica-tion in order to reserve the latter for the siliceous emanations so common in connection with the sulfide ore deposits of this and many other districts. Broadly, it is meant to include all silicification in this district prior to the introduction of the jasperoid, the latter being contemporaneous with the ore-bearing solutions.

Jan 1, 1935

By F. A. Crossley

The key to disagreements between Blackburn's findings and mine is the word equilibrium". My work attempted to define the equilibrium diagram of the titanium-rich end of the Ti-A1 system. It can readily be shown that Blackburn's conclusions are based primarily on the examination of structures substantially removed from equilibrium. The diagram presented in Fig. 16 is properly labeled a "phase diagram". However, it appears that Blackburn either does not understand or does not accept the difference between "phase diagram" and "equilibrium diagram" as defined in the Metals Handbook.17 The conflict lies not in Blackburn's data but in his interpretation of it, and his use of "transformation", "phase diagram", and "equilibrium diagram" as synonymous terms. I share his view that the light microscope is much inferior to the transmission electron microscope for the study of transformations; but this fact does not render the light microscope useless or untrustworthy. The difficulties experienced with the Ti-A1 system have not been due to the limitations of the light microscope, but rather to the extreme sluggishness in achieving equilibrium at temperatures below 1000° C. Were it not for the light microscope employed with polarized light, the twin phase syndrome' might still be unrecognized and, as a consequence, still adding to the confusion of Ti-A1 investigations. (Ref. 1 should read ... Contract No. N161-25952 ... vol. 236.) Other, more sophisticated techniques, including electron transmission, simply confirm the erroneous tentative conclusions drawn from observations of structures due to the twin-phase syndrome. By the standards of most of the investigations of the Ti-A1 systems, seven of the fifteen compositions investigated by Blackburn were seriously contaminated with oxygen. The writer has found that 0.1 wt pct 0 shifts the a + Ti3A1 boundary to 1 at. pct lower A1 content at 700°C. At constant aluminum content, this corresponds to a temperature shift of the boundary of +25°c.18 Blackburn advises that the first group of alloys contained 0.1 to 0.15 wt pct 0, bur he does say whether the analyses were performed on as-received material or on specimens in their final state of heat treatment. This is especially important considering the 20-mil-thick starting materials. If specimens had been annealed in the two-phase a + 6 region it would have provided an indication of the final degree of oxygen contamination since up to about 12 at. pct A1 the boundaries of this region are well-defined for low-oxygen alloys. Blackburn questions the capability of light microscopy in determining phase boundaries in the Ti-A1 system. I submit that the a/a + Ti3A1 boundary in Fig. 1 of Ref. 1 over the composition range from 10 to 18 at. pct A1 was determined by dilatometry and supported by electron diffraction. Specimens of alloys containing 8, 10, 12, and 14 at. pct A1 were aged at 550°C for 1000 hr (under stress of 5000 psi to accelerate the tendency to equilibrium) and then fractured in tension at room temperature. Collodion was applied to the as-fractured (unetched) surface and, when stripped, carried away particles identified by electron diffraction as Ti3A1. Perhaps Blackburn will explain why these electron diffraction data were ignored. At this time, a technique for revealing or indicating

Jan 1, 1969

By G. R. M. Del Giudice

The term "slime-coating" is not new in the art of flotation; the phenomenon has been observed and described by Taggart;(l)† Taggart, Taylor, and Ince;(2) and by Ince.(3) Notwithstanding that flotation was introduced for the treatment of finely crushed ore, the adverse effects of slimes have been recognized since the earliest days of the process, and the Elmore, Delprat, Potter, and other processes actually specified desliming of the ore prior to treatment. The cause of this trouble has been studied and described by Taggart;(1) Taggart, Taylor, and Ince;(2) Ince;(3) Morrow and Griswold;(4) and by Gaudin and Malozemoff.(5) Old Theory of Slime-coatings At present, so far as published work shows, there seems to be but one theory for the mechanism of slime-coatings. Ince(3) states that they are due to attraction between electrostatic charges of opposite sign on the sulfide and on the slime particles, supporting this theory by migration experiments in the Burton tube. He also used the microscope in conjunction with a glass cell employed by Beans and Eastlack(6) in studying migration, but met with interference from endosmosis. Several attempts have been made in the Department of Mineral Dressing at Columbia University to duplicate Ince's experiments with the Burton tube, but the results have never been convincing. Formation of precipitates which settled through the pulp levels, and evolution of gas at the electrodes, which disturbed the interface between the pulp and the distilled water above it, seriously interfered with observations. However, by use of the migration cell shown in Fig. 1, endosmosis effects and the disturbances due to precipitation and gas evolution were avoided, and distinct and reproducible migrations or absence of migration were observed. The cell was made of bakelite and had platinum electrodes. Objectives were employed which had a working distance of at least three millimeters,1 and the parts of the mounting which came in contact with

Jan 1, 1935

By Frank C. Appleyard

Gypsum, the dihydrate form of calcium sulfate, has a history of usefulness to man dating back several thousand years, and a worldwide industry has been built on the mining and processing of this versatile industrial mineral. However, anhydrite, the other principal calcium sulfate mineral has very limited use, so much so that separate statistics for it are not always kept, but are usually included with those for gypsum. Although often found in close association, the two minerals have important chemical differences in that anhydrite is the anhydrous form of calcium sulfate (CaSO,) whereas gypsum is the dihydrate (CAS0;2H20). These two molecules of combined water result in significant differences in hardness, density, and solubility of the two minerals. However, of most importance is the difference in thermal properties wherein gypsum, upon the application of a modest amount of heat, can be converted to the hemihydrate of calcium sulfate (CaS0;Vi H,O) or plaster of paris, an intermediate product upon which is based over 90% of the value of all calcium sulfate end products. Anhydrite, on the other hand, is inert at these temperatures and its uses have been limited to only those few cases where calcium sulfate in the anhydrous form may have an advantage. The earliest known use of gypsum plaster dates back some 5000 years to the time of the Pharaohs of Egypt who had discovered that gypsum rock, when exposed to fire, broke down into a powder which when mixed with water would form a putty that could be "plastered" on a rough mud brick or stone wall to make a smooth finish. It was used down through the centuries in a limited way for ornamental purposes, but did not achieve wide acceptance because of its quick (25 to 30 min) setting or hardening time which made it difficult to use. The first real understanding of gypsum chemistry was developed in France about 1755, and the gradual growth of its present utilization dates from that time. In the United States, the first utilization of gypsum was to grind it to a fine material for use as a soil conditioner at about the time of the Revolutionary War, and the term "land plaster" for ground gypsum has remained in use. Another cementituous material-lime or calcium oxide-had become the usual plastering material, but by about 1870 a method for retarding the set of gypsum plaster was discovered and it has today almost completely replaced lime as a plastering material. In recent years, gypsum products sold in the United States have reached a total valuation of approximately $500 million per year as illustrated in [Table 1].

Jan 1, 1975

By O. W. Simmons, L. W. Eastwood, C. M. Craighead

Eighty-four quaternary titanium-base alloys from the following systems were investigated: 1. Titanium-chromium-carbon-nitrogen. 2. Titanium-chromium-carbon with copper, vanadium, molybdenum, manganese, iron, or nickel. 3. Titanium-chromium-nitrogen with vanadium, molybdenum, or nickel. The tensile properties, minimum bend radii, hardnesses, response to heat treatment and aging treatment, and phase relationships of these alloys are reported. HIS paper is the third in a series describing J- titanium-base alloys. The first paper describingdescribed titanium binary alloys, and the second contained data on a large number of titanium ternary alloys. Eighty-four heats, comprising three groups of quaternary titanium-base alloys, are described in this paper as follows: 1. Titanium-chromium-carbon-nitrogen alloys. 2. Titanium-chromium-carbon alloys containing copper, vanadium, molybdenum, manganese, iron, or nickel. 3. Titanium-chromium-nitrogen alloys containing vanadium, molybdenum, or nickel. The methods of preparing, fabricating, and testing the alloys are described in the paper Binary Titanium Alloys. Quaternary Titanium - Chromiurn - Carbon -Nitrogen Alloys The properties of titanium-chromium-nitrogen and titanium-chromium-carbon ternary alloys have been described in the paper Ternary Alloys of Titanium. Because small amounts of nitrogen and carbon both appear to be somewhat beneficial, these additions have been investigated fairly completely in quaternary alloys containing chromium at the following levels of composition: 2.5, 3.5, and 5.0 pct chromium 0.25 and 0.5 pct carbon 0.1 and 0.2 pct nitrogen Mechanical Properties: The mechanical properties of these alloys are listed in table I. Fig. 1 and 2 show graphically a comparison of the tensile properties and hardnesses of quaternary alloys with those of the titanium-chromium binary alloys. Fig. 1 shows the comparison at 0.25 pct carbon, whereas fig. 2 shows the comparison at 0.5 pct carbon. It is concluded from these data that 0.25 pct carbon and 0.1 pct nitrogen are desirable additions to the 5 pct chromium-titanium base. It is further concluded that most of this improvement is produced by the nitrogen and that carbon is either harmless or mildly beneficial, at least up to 0.25 pct. Structure and Transformation Range: The effects of carbon and nitrogen on the transformation range of the titanium-chromium alloys were determined as part of the routine investigation. Additions of 0.25 pct carbon and 0.1 pct nitrogen had no appreciable effect upon the transformation range. However, the addition of 0.25 pct carbon and 0.2 pct nitrogen definitely raised the beta solvus temperature, as shown by fig. 3.

Jan 1, 1951

By C. F. Baes, H. H. Kellogg

The effect of dissolved sulphur on the surface tension of liquid copper has been measured by a sessile-drop method at 1120°C. Sulphur is highly "surface active" in liquid copper; the surface tension lowering is about 650 dynes per cm for a sulphur content of 0.6 pct. The degree of adsorption of sulphur on the liquid copper surface has been calculated, and various models of the surface layer have been tested against the results. THE science and technology of surface chemistry and physics at room temperature are relatively advanced, and the engineer possesses a background of information that allows him to predict and control many phenomena—such as frothing, emulsifica-tion, wetting of solids by liquids, flow through capillaries, adsorption, mineral flotation, penetration of porous bodies by liquids—which are related to the behavior at interfaces. Surface phenomena in high temperature systems are probably of equal importance to the metallurgist and ceramist, but at present are incompletely understood. Frothing of liquid slags, penetration of refractories by liquid metals and slags, infiltration of powder metallurgy "skeletons" by liquid metals, bonding of metals to ceramic oxides in the manufacture of "cermets," wetting of one metal by another for purposes of soldering and welding, are but a few of the many phenomena of metallurgy that are controlled by surface behavior. Concerning the most elementary of surface properties—the gas-liquid surface tension—the existing data on liquid metals are inadequate. For the surface tension of "pure" metals the results of different investigators differ by 10 or 20 pct. The role of surface-active agents in liquid metals is relatively unknown, and it is not unlikely that the discrepancy in the values for the surface tension of pure metals is due to the presence of traces of surface-tension-lowering impurities in the samples. Based on analogy to room-temperature systems, the highly surface-active impurities in liquid metals should be elements or compounds of limited solubility in the liquid metal and possessing considerably weaker in-termolecular bonding forces than the metal itself. The nonmetals of the V, VI, and VII groups of the periodic table might be expected to act in this way. The experimental work in this paper represents a study of the surface tension of pure liquid copper in hydrogen at 1120°C, and the effect of dissolved sulphur (which is a strongly surface-active agent in liquid copper) on the surface tension of copper. The Gibbs equation has been applied to the results and an attempt made to correlate the surface tension behavior with two models of the interfacial layer. The sessile-drop method for surface-tension measurement at high temperatures which was used in this investigation has been described by several investigators.1,2 It involves the measurements of the dimensions of a stationary liquid drop on a horizontal surface. From these dimensions and the liquid density, the surface tension of the liquid may be calculated either by means of various approximate formulas, or more accurately by means of the Bash-forth and Adams tables.- or liquid drops which exhibit a contact angle greater than 90°, by far the simplest dimensions to measure are those indicated in Fig. 1, i.e., the diameter of the maximum horizontal cross section (2X) and the maximum height (Z) above this plane. In order to calculate the contact angle and the volume of the drop, the diameter at the base of the drop (2a) and the total height (h) also must be measured. Upon investigation of the literature, the authors failed to discover a concise statement of the accuracy of the method when used in conjunction with the Bashforth and Adams tables, hence a careful examination of the tables was made and the curve shown in Fig. 2 was constructed. The "error factor," plotted as the ordinate, is the factor by which the

Jan 1, 1954