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By W. R. Crane

THE effect of mining in the red-ore mines of the Birmingham district has been observed for some time, but, except in a few localities, little difficulty has been experienced from disturbance of cover. Cave-ins near the outcrop and fracturing of the surface at greater distances are the most pronounced manifestations of disturbance, while limited areas at points distant from the outcrop and under greater depth of cover have actually subsided. There is no doubt but that in time, because of failure of pillars, extensive fracturing and widespread settlement of the surface will result, particularly along the slope of Red Mountain, where mining has been under way for many years. Were it not that the orebed is overlain by one or more water-bearing formations, the fracturing or settlement of the surface would not be serious; but because of these formations, fracturing of the top rock may in itself be of sufficient importance to warrant the adoption of protective measures. Until development openings and surface plants are transferred to Shades Valley, protection of the surface will probably not be considered imperative, as the area involved is not of particular value for agricultural or building purposes. Further, the collapse of pillars over a wide area may develop squeezes that, if not controlled, may jeopardize the integrity of the mines and necessitate a change in development, from slopes to vertical shafts, at a much earlier period than is now contemplated. The occurrence of heavy beds of strong tough materials at varying distances above the orebed make it doubtful whether any serious disturbance of the surface will be experienced at any considerable distance from the outcrop, although some settlement will probably take place. It is certain, however, that no great volume of water will enter the mines from fracturing of the Fort Payne chert bed, as this is known to be a compact and practically impervious formation beyond the leached zone. Not so much can be said, however, regarding other possible sources of water, as pervious beds and through faults that may be encountered in future mining operations.

Jan 8, 1925

By Walter H. Bucher

This symposium is designed to lay the basis for a general discussion of the place of geophysics in the training of geologists. As there is danger that in the ensuing debate individual interests may be given emphasis out of proportion to their place, we shall do well to view the whole field of geological inquiry in order to see the problem in true perspective. The Nature of Geological Inquiry "Basic" and "Complex" Sciences It is convenient to divide all science into two major divisions, the basic and the complex sciences. The basic sciences separate out from reality such entities as "substances" and "movements," describe their behavior in terms of arbitrary units of measurement and derive from them by progressive abstractions concepts and patterns of behavior that exist between them, so-called general "laws" and "properties" of nature. The complex sciences, on the other hand, deal, with little or no abstraction, with those objects of reality that are accessible to man in the atmosphere, the hydrosphere, the lithosphere and the biosphere. Their work comprises two types of inquiry. One is concerned with abstractions to the extent of dealing with types rather than individuals—that is, with such things as plants, animals, protoplasm; clouds, streams, gla- ciers; volcanoes and mountain ranges. It comprises the search for general properties and patterns of behavior or "laws" that characterize the objects and their reactions to each other. These properties and laws apply always, everywhere. They are independent of the stream of time. We may call the results of this sort of inquiry timeless knowledge. The other type of inquiry is concerned with the objects themselves—that is, with this animal and that plant; this river system and that mountain chain; this glacier and that valley. Like all concrete objects in nature, they are subject to change with the passage of time, especially when it is measured in years, centuries, eons. The characteristics by which we recognize them —indeed, their very existence—are dependent on their position at this point in the stream of time. This we may call time-bound kntowledge. The so-called descriptive sciences are all bound to the past of which the objects of their study are the product and through which alone their present properties call be understood. They are historical sciences. This obvious fact is easily overlooked, which leads to serious misunderstanding, as we shall see later. Dynamic Geology With this broad picture in mind, let us now examine the nature of geological inquiry, defining, for the purposes of this discussion, geology as the science of rocks. Air is not a rock; water is. Meteorology and climatology are, correspondingly, gen-

Jan 1, 1946

By Joseph F. Shirley

A froth flotation plant to recover byproduct molybdenite must be designed specifically for the selected separation process and the type of ore being treated. However, some general rules concerning byproduct molybdenite plant design can be suggested that would be valid for most processes. The term byproduct molybdenite in this paper is limited to the recovery of molybdenite from copper porphyry ores, which essentially amounts to selectively separating molybdenite from copper and iron sulfide concentrates. In addition, most of the discussions would apply only to the almost universally used approach of floating the molybdenite and depressing the copper and iron sulfide minerals. Thickener It is considered essential that the feed to a byproduct molybdenite plant be thickened prior to being treated for molybdenite recovery for the following reasons: 1) Thickening allows the rougher and any preconditioning stages to be operated consistently at the optimum percent solids. 2) Generally, the size of equipment used for pretreatment and the rougher flotation is considerably smaller and less expensive than if the copper flotation concentrates were treated directly. 3) The removal of as much water as practical by thickening removes flotation reagents added in the copper flotation circuit, especially frother which can be quite troublesome in a byproduct molybdenite plant. Although thickening of the molybdenite plant feed has long been recognized as necessary to optimum metallurigcal results, very often this area has been designed poorly. The thickener should be sized so that it can produce a consistent thickened product containing 60 to 65% solids without the use of flocculants. Some plants are only able to thicken to 45 to 50% solids consistently while other plants let the percent solids vary from 45 to 60% over a 24-hr period. While the former is more desirable than the latter, in many cases better metallurgical results could be obtained if the percent solids could be held consistently close to 60%. Probably the simplest and most satisfactory system of handling the thickener underflow is to spigot it into a sump, using a sphincter type valve for the orifice, controlled by a density meter. Another satisfactory approach is to use an ODS type pump to meter the underflow. There are other methods of handling thickener underflow which work satisfactorily as long as the amount of copper concentrates entering the thickener is relatively uniform. However, they often fail to operate satisfactorily when there are large fluctuations in the thickener feed rate due to fluctuations in ore tonnage and/or copper grade. If the percent solids in the plant feed could be held close to 65%. There is the possibility the molybdenite plant tailing would not have to be thickened prior to the copper filter plant. This means that the molybdenite rougher float would have to be conducted at 45 to 50% solids with all the cleaner tailings returned to the rougher for dilution. Admittedly, in some situations this approach would be impossible, but if capital or plant area is limited, it should be considered.

Jan 1, 1981

By W. T. Allan

RAW bituminous coal has been in general use as a blast-furnace fuel in Scotland for the last century, and although its use has now been largely abandoned and it has been replaced by coke in the majority of the few furnaces which are at, present in blast in this country, coal-smelted pig iron is not yet a thing of the past; it is still being produced and mar-keted in competition with the more cheaply smelted product of the coke-fired furnace. Various factors have influenced this change in practice; the once plentiful deposits of coal of a suitable nature for the blast furnace are now not so easily obtainable; native blackband and clayband ironstones which are easily smelted in the coal-fired blast furnace, although still far from being exhausted, are not available except at a. cost that is somewhat higher than that of imported ores, making them unattractive to the ironmaster that is compelled by circumstances to smelt his iron at the lowest possible cost. Within the last 15 years overproduction of synthetic nitrogen has led to progressive reductions in the price of sulphate of ammonia, the recovery of which together with the other by-products before that time materially assisted in reducing the working costs of the coal-fired furnace. Now the sale of the by-products recovered yields a diminished profit. When the cost of the product is the only consideration the small, slow-smelting, coal-fired blast furnace cannot compare with its large, modern, coke-fired competitor. Other `considerations do not by any means all support the same side of the argument. In the smelting of pig iron to be used in the manufacture of steel where the quality of the final product depends so largely upon the control of the conversion process and so much less upon the physical quality of the pig iron used, the physical properties of the pig iron do not exert any appreciable influence upon the quality of the steel produced, therefore the methods employed in the smelting of the pig iron matter but little so long as the requisite chemical composi-tion is reached. On the other hand, in ironfounding where the simple melting of the pig iron, which is the only treatment it receives before being cast into its final form, does little or nothing to modify its original charac-

Jan 1, 1937

By F. C. Stanford

The work of an engineer is to direct natural forces so that the: bring about the results that he wishes to secure. Heretofore he ha concerned himself chiefly with physical forces and inanimate objects until he has secured a truly marvelous degree of control over them The great problem of the present age is to secure a like degree of know1 edge and control of the human factor. Progress has already been made along this line, but it is only a beginning. Wilhelm Ostwald says tha scientific knowledge enables a man to be a true prophet; but it must be remembered that a good many people do not seem to be able to main tain a high average in prophecy. In short, 'the average of knowledge is not equal to the average needs of the present time, but continually fails to keep pace with it. It has been aptly said that the really essentia need of the period is for more brains; if we only had sufficient knowledg and sagacity we could not only solve all difficulties, but prevent then from arising. This generalization holds good for an industrial organization. Th most vital need of the management is for more brains. The logica course for an engineer in charge of an industrial organization is, therefore to direct whatever forces may be at his command toward the development training, and guiding of all the brains in his organization. This is easie said than done, for it involves the carrying on toward two objective: the maximum of productive work, and the development of the individual who perform it. This is essentially like the rebuilding and enlarging of plant, keeping it in full operation the while. On the other hand, if th aim is merely for maximum production from an organization, withou offering opportunity for development, the final outcome will necessari be like that of a plant that is driven at full capacity without stoppin for repairs or improvements; it eventually becomes so run down th either a complete rebuilding is necessary or else it has to be abandone

Jan 1, 1918

By Thomas Read

PERSONNEL work is a term recently introduced to cover the great variety of activities in industrial work that deal with the human factor. Much attention has been focussed upon individual phases of personnel work, such as accident prevention, sanitation, "welfare" work, reducing labor' turnover, and so on. In most cases these activities have been carried on as though they were distinct and separate fields; as a matter of fact, they are only different phases of the single problem of human engineering, and each has important and fundamental relations with the others. Thus, for example, high labor turnover is one of the most .important causes of a high accident rate, and unsatisfactory housing conditions are an important cause of labor turnover. In the early stages of the study of these problems, it was necessary to take them up separately; the time has now arrived at which it is desirable to consider them as a whole in order to bring them into the right relation to each other. When thus considered as phases of an interrelated whole, they may be grouped as personnel work. A discussion of the importance of personnel work as a means of in creasing dividends in industry may be objected to by some as a too materialistic way of looking upon work that is humanitarian. Nothing could he more mistaken than such an opinion. Humanitarianism, per se, has no place in industry, and nothing is gained and much is lost in pre tending that it has. The only reason why a corporation engages in business is to make profits, and any activity of the corporation that does not tend either directly or indirectly toward that end is poor business. It is equally poor business to overlook any activities that do tend indirectly to the making of profits. On this basis, personnel work can be justified as a corporate activity; there is no justification whatever for abstract humanitarianism from the business standpoint. One characteristic of the American workman is a general high level of intelligence, and it is an insult to intelligence to ask a man to believe that anything so impersonal as a corporation is really desirous of benefiting

Jan 10, 1917

By H. S. McQueen

The insoluble-residue method for the examination and correlation of limestones and dolomites, or other sedimentary rocks containing calcium and magnesium carbonates, originated and was developed in the laboratory of the Missouri Geological Survey. The numerous and ever-increasing problems in the field of applied geology, and the need for a tool or aid in the solution of them, led to experimental work with samples collected from deep wells, in the early part of 1924. The success attained, almost at the outset, with this method was so great that the method has now been developed from the state of the experimental to the realm of large-scale, every-day routine. In a previous paper the writer1 described the procedure in detail and the characteristics of the residues obtained from certain Paleozoic formations in Missouri. The purpose of the present paper is to discuss the economic application of the insoluble-residue method. Developmental History Within the Ozark region of southern Missouri the geologic column consists of Lower Ordovician (Canadian of Ulrich) and Upper Cambrian formations, which are composed mainly of dolomite with subordinate amounts of sandstone, shale and limestone. Chert is found to some extent in all except one of the dolomite formations. The stratigraphy of the region is complex because the dolomites have lithologic similarities, fossils are few and often poorly preserved, and identifiable horizons within the comparatively thick formations are not common. Although considerable stratigraphic work of an areal nature had been done for a period of many years by the Missouri Geological Survey, the detailed geologic succession had not, until a few years ago, been systematically worked out. The problems of subsurface stratigraphy were even more complex. This region constitutes the main ground-water province of the State of Missouri and within it wells of varying depths are drilled in order to obtain supplies of ground water. In the work of the State Geological Survey in connection with the drilling of water wells for public supplies * Published with the permission of the Director, Missouri Geological Survey and Water Resources. Manuscript received at the office of the Institute Feb. 20, 1936. Assistant State Geologist of Missouri; Missouri Geological Survey, Rolla, Mo. References are at the end of the paper.

Jan 1, 1937

By Walter H. Bucher

This symposium is designed to lay the basis for a general discussion of the place of geophysics in the training of geologists. As there is danger that in the ensuing debate individual interests may be given emphasis out of proportion to their place, we shall do well to view the whole field of geological inquiry in order to see the problem in true perspective. The Nature of Geological Inquiry "Basic" and "Complex" Sciences It is convenient to divide all science into two major divisions, the basic and the complex sciences. The basic sciences separate out from reality such entities as "substances" and "movements," describe their behavior in terms of arbitrary units of measurement and derive from them by progressive abstractions concepts and patterns of behavior that exist between them, so-called general "laws" and "properties" of nature. The complex sciences, on the other hand, deal, with little or no abstraction, with those objects of reality that are accessible to man in the atmosphere, the hydrosphere, the lithosphere and the biosphere. Their work comprises two types of inquiry. One is concerned with abstractions to the extent of dealing with types rather than individuals—that is, with such things as plants, animals, protoplasm; clouds, streams, gla- ciers; volcanoes and mountain ranges. It comprises the search for general properties and patterns of behavior or "laws" that characterize the objects and their reactions to each other. These properties and laws apply always, everywhere. They are independent of the stream of time. We may call the results of this sort of inquiry timeless knowledge. The other type of inquiry is concerned with the objects themselves—that is, with this animal and that plant; this river system and that mountain chain; this glacier and that valley. Like all concrete objects in nature, they are subject to change with the passage of time, especially when it is measured in years, centuries, eons. The characteristics by which we recognize them —indeed, their very existence—are dependent on their position at this point in the stream of time. This we may call time-bound kntowledge. The so-called descriptive sciences are all bound to the past of which the objects of their study are the product and through which alone their present properties call be understood. They are historical sciences. This obvious fact is easily overlooked, which leads to serious misunderstanding, as we shall see later. Dynamic Geology With this broad picture in mind, let us now examine the nature of geological inquiry, defining, for the purposes of this discussion, geology as the science of rocks. Air is not a rock; water is. Meteorology and climatology are, correspondingly, gen-

Jan 1, 1946

By Earl S. Greiner, Eric R. Jette

The literalure on the binary alloys of iron and silicon has been reviewed by Stoughton and Greiner.1 Another even more extensive and detailed survey of the present knowledge has been prepared under the auspices of the Alloys of Iron Research Committee by Greiner, Marsh and Stoughton. Since the latter surrey has already been issued in its preliminary form, it will be unnecessary to review the literature in the present article. However, in this connection there should be noted the important work on the crystal structures of the iron-silicon alloys by Phragmén,2 who investigated the entire system, identified the various phases and determined the homogeneity ranges of these phases. It was evident in the surveys cited above that in the range from 0 to 15 per cent silicon, which includes the commercially most important, alloys, the results obtained by thermal analysis, microscopic examination and the determination of electrical, magnetic and mechanical properties were extremely confusing. From time to time various compounds between iron and silicon have been postulated to account for the results yielded by the classical methods, and much argument has ensued. It was presumed that if compounds occurred which are sufficiently diverse in their properties to account for the characteristics of the alloys, they should be recognizable as separate phases but satisfactory proof of this sort has not been found by thermal or microscopic methods. Contributing to the confusion is the fact that the electrical, the magnetic and some of the mechanical properties are "structure sensit'ive"; i. e., they are influenced to a marked degree by the presence of minute amounts of impurities, the specific characters of these impurities, the grain size, the character of the grain boundaries, small general or local strains, etc. Thus interpretations of the discontinuities in the various property versus composition curves that identified these discontinuities with phase changes or compound formation have always been open to question.

Jan 1, 1933

By W. Francis

OF THE methods that have been used for studying the chemical composition of coal, attack by reagents has not, in general, yielded much information. Most of the reagents used have been strong oxidants such as nitric acid or Schulze's solution. The use of a milder oxidizing agent, such as air at low temperatures, enables progressive changes in the character of the coal substance to be studied and thus helps toward an understanding of its constitution. British bituminous coals frequently have a banded structure. These bands (of four types) can be separated one from another and have been found to possess markedly different chemical characteristics, even when taken from contiguous portions of the same lump coal. It has been found convenient to give each of the ingredients of banded coal a distinctive name, more or less descriptive of its appearance, and the study of the chemistry of bituminous "coal" in England has resolved itself into a study of each ingredient separately. . The coal chosen for this work was taken from the Top Hard seam at East Kirkby colliery, Nottinghamshire, a detailed chemical analysis of which has been recorded by Baranov and Francis.1 The banded structure was well marked and the bands could readily be separated. The research was confined to the brilliant vitreous bands (vitrain), the dull hard bands (durain) and the "sooty partings" (fusain); for previous work had shown that the fourth type, to which the name clarain has been given, is intermediate in character, chemically, between vitrain and durain.

Jan 3, 1925

By M. C. Fuerstenau, J. D. Miller

The response of calcite to flotation with saturated fatty acids and alkyl sulfonates of various chain lengths is presented. The amount of collector re-quired for flotation is shown to decrease systemati-cally with increasing carbon content from 8 to 12-carbon atoms per molecule. This systematic flotation response is correlated with the solubilities of the calcium-collector salts, which were established with a nephelometer. The 14-carbon collectors deviate from this systematic behavior, and no flotation is possible with the 16-carbon homologs. As determined by infrared analysis, the mechanism of collector adsorption involves a specific chemical reaction be-tween the collector and the surface. A reaction of the form CaCO3(s)+ 2 RCOO"=*=Ca(RCOO)2(s) + C03= is suggested. The pH of the system is also shown to be a most important parameter as it controls the carbonate, calcium, and collector ion concentrations in solution and thus controls flotation response. The importance of hydrocarbon chain length of collectors was recognized early, and various studies have been made on this aspect of flotation. Wilkinson, ' for example, noted that as the chain length of alkyl xanthates is increased, the amount of collector required for flotation of sphalerite is decreased. The same effect has been shown in the flotation of galena.2 Similar results were obtained when malachite3 and calcite4 were floated with various fatty acids. DeBruyn5 has shown that a similar phenomenon occurs when quartz is floated with amines at constant pH. Recently, Fuerstenau, Healy, and Somasundaran6 correlated this phenomenon with the van der Waals cohesive free energy of association of the hydrocarbon chains. It seems unlikely, however, that chain association could be involved in the sulfide and carbonate systems with the collector additions employed, especially with the short-chain xanthates. Rather, it would seem that the decrease in collector concentration with increase in chain length noted for flotation is related to the solubility of the metal-collector salt. The purpose of this investigation is to verify this premise and also quantify this phenomenon if possible. Calcite was selected for study with both alkyl sulfonates and saturated fatty acids as collectors. EXPERIMENTAL MATERIALS AND METHODS The collectors used in this investigation ranged from 8 through 14 carbon atoms per molecule. The fatty acids had a reported purity of greater than 99%. The sodium alkyl sulfonates were provided by the Marathon Oil Cot, Littleton, Colorado, and had the

Jan 1, 1968

By E. A. Holbrook

Research, primarily, is finding out the truth. Research applied to enigeering opens the door to new principies and processes, the application of which benefits mankind in a material way. The engineer believes that investigation instituted with the primary view of making the results directly applicable to the industries is the highest type of research. Coal is essentially the basis of modern industrial civilization; therefore, any considerable research pertaining to coal must link itself to the industry by practical application of the results of the research. In other words, all investigational work connected in any way with coal leads to conclusions that permit a better understanding of the origin, nature of occurrence, composition, better and safer mining, more careful preparation, or greater efficiency in utilization of coal. Modern engineering research has been fostered essentially by universities and in the laboratories of institutions of learning. Coal problems that lend themselves to solution in the laboratories have been first attacked and are perhaps the farthest toward solution. For example, a great amount of research work has been carried out with the various phases of chemistry connected with coal. On the other hand, the equally important problems connected with methods of mining have received but little attention, primarily because their solution involves the continued use of a great and expensive laboratory, which is none other than the mine itself. As many of the problems already solved have had chemistry as their background, so many of the problems unsolved have physics as their background; there are also unsolved problems that deal in coal economics. Even psychology must be called upon in future coal-mining research as a basis for solving those great problems that deal with human relationships. 'In general, considerable advance has been made in coal research dealing with chemistry, not so much progress has been made with problems having physics and engineering as a background, while there is a tremendous range of untouched problems that deal essentially with business and psychology. Research in coal mining is not a new development. In the chronicles of the northern coal trade as published in the Transactions of the North

Jan 1, 1920

By R. S. Handy

DOES hand-sorting of mill feed pay? The fact that the practice is so general would seem to indicate that there must be good reasons for following it; yet, to my mind, the advantage in many cases is doubtful enough to invite a thorough discussion of the subject, in an effort to determine under what conditions hand-sorting does pay. A typical sorting plant in the Coeur d'Alene district handles about 800 tons of mine-run ore per day. The material is run over a grizzly with about 4-in. opening; the oversize is crushed to about 4-in. size and joins the undersize, and the whole product is washed and screened on trommels with about 1 ½ -in. openings. The oversize from these trommels is spread on a belt and the waste and first-class ore are sorted out by hand, the residue being further crushed, and passes, together with the trommel undersize, into the mill feed bins. About 50 tons of shipping ore and 150 tons of waste are sorted out per day, leaving about 600 tons of mill feed. To sort out this material requires 20 ore sorters and five bosses and repairmen. The normal cost of hand-sorting is about 16 c. per ton of run-of-mine ore, or 65 c. per ton of material sorted out. I believe that straight crushing and milling of the run-of-mine ore, in this case, is not only cheaper, but is metallurgically moree canonical and efficient than hand-sorting followed by milling of the residue. At one of the Bunker Hill rock-houses, 1250 tons of run-of-mine ore are reduced to pass 30-mm., or about 1 ¼ -in. opening in six hours, requiring five men. The equipment and the power consumed are not greatly different from that required in a sorting plant of the same capacity, and the normal cost of thus preparing the feed for milling is under 3 c. per ton of mine product. The relative cheapness of this method as against hand-sorting is thus clearly established, the saving being about 13 c. per ton. If there is any virtue in hand-sorting, then, it must lie in the metallurgical results achieved.

Jan 4, 1918

By W. T. Cardwell, R. L. Parsons

This paper discusses the practical problem of estimating a single equivalent permeability for an oil reservoir, or a portion thereof, whose actual permeability varies in an irregular manner. Limiting averages for general types of permeability variation are developed, and illustrated by examples involving important, specific types of variation. Introduction The theory of the flow of fluids through porous media1"4 is becoming increasingly important in predictions of oil-reservoir behavior. In practical applications, however, reservoirs are seldom found to which simple theory strictly applies. Actual reservoirs have complicated shapes and nonuniform permeabilities and porosities. This paper discusses the problem of estimating a single equivalent permeability for an oil reservoir, or a segment of an oil reservoir, whose actual permeability varies in an irregular manner. The equivalent permeability of a reservoir segment is defined as the permeability of a homogeneous segment of the same dimensions that would pass the same flux under the same pressure drop- It is the permeability value that can be used in simple theoretical formulas to calculate the reservoir behavior. To the authors' knowledge, previous theoretical calculationst on systems of nonuniform permeability have been carried out only by Muskat'"; and he has not dealt with irregular variations, except in writing down the general differential equation for the pressure in variably permeable systems.lb In practical work, many calculations necessarily have been made to estimate equivalent permeabilities from the permeabiiity profiles obtained by core analyses. Regarding such calculations, Johnston and Sherborne6 say: Simple arithmetic and weighted averages have been tried on many wells and it has been found that, where frequent sampling has occurred, the arithmetic average is as satis- factory as a weighted average. It is possible that the application of statistical methods to the analysis of permeability data as recently presented by Law8 may prove fruitful. L,, has made a valuable contribution in showing how statistical analyses may aid in picturing the characteristics of a reservoir from those of a necessarily limited number of core samples. It is believed however that the particular problem of the estimation of equivalent permeabilities can be most directly approached from a fluid dynamical viewpoint as given in the present paper. An example is presented of the use of the conclusions herein in conjunction with Law's method. Theory In order to approach the problem of heterogeneity simply, it is interesting to consider a square block composed of four smaller, homogeneous, square blocks of porous medium, two of which have a

Jan 1, 1945

E. E. THUM,* Salt Lake City, Utah (written discussion?).-While the present paper is confined exclusively to the microstructure of fusion welds, it may be of interest to draw attention to certain appearances existing in resistance welds such as spot or butt-welded joints produced by the Thomson process. For instance, a butt weld between two pieces of carbon tool steel (carbon about 0.90 per cent.) will show concentric ellipsoids of the various materials from pearlite to martensite. The surfaces of demarcation are quite well defined, the center of the ellipsoid being at the intersection of the axis of the piece and the plane of the weld. Often these unannealed welds show a troostitic center; evidently this core was not quenched as rapidly as the surrounding shell. Such specimens are beautiful samples for instruction purposes. An annealed butt weld of this kind will show a very well defined central ellipsoid of decarburized, materials. It is interesting to consider the reason why this change takes place. It must be understood that the heat is on the metal for a very short time, possibly 30 sec. It is therefore evident that the decarburization, or migration, of the carbon takes place with extreme rapidity. Since no blowholes are evident in a well-made butt weld, the deoxidizing air and the products of combustion must migrate with the highest speed; second, the carbon might migrate back into the stock; or, last, a large proportion of the pearlite may be extruded with the hot metal, which forms a fin at the plane of weld. Examining these possibilities in detail, it is not probable that such deep-seated decarburization, extending with maximum effect to the very center of a 2-in. round bar, is done by reaction with the oxygen of the air. This would postulate entrance of oxygen and egress of carbon oxides in large quantity without leaving behind traces in the form of oxides or

Jan 5, 1919

By W. B. Price

AT the New York meeting of the American Institute of Mining-and Metallurgical Engineers held in February, 1926, W. H. Bassett and J. C. Bradley presented a paper entitled "Exudations on Copper Castings."§ The purpose of the present paper, as the title suggests, is to call attention to somewhat similar phenomena which the authors have encountered in brass and bronze. From a study of the examples given, a more-or-less speculative theory of "inverse segregation" is advanced. PROTUBERANCES ON ADMIRALTY BRASS In the rolling mill of the Scovill Manufacturing Co., there have been found quite commonly bars of certain alloys which had a sort of shaggy roughness on the surface due to slight metallic protuberances. No special attention was paid to these until some bars were found on which these protuberances were heavy enough at the bottom of the bars to produce a blistered appearance. A sample of the protuberances was milled off the surface of the bar illustrated (Fig.. 1a) and upon analysis was found to contain 66.66 percent. copper, 4.02 per cent. tin and .03 . per cent. lead, whereas the average composition of the bar was 70.21 per cent. copper, 1.21 per cent. tin, and .01 per cent. lead. A sample of the shaggy-rough protuberances at the -very top of a bar was also analyzed and was found to contain 2.45 per cent. tin, indicating that it was probably of the same origin as the blistered areas. These results were not entirely unexpected for previous analyses of this alloy had -revealed that the surface was richer in tin than the rest of the bar. This, of course, is contrary to what we would expect from a consideration of the equilibrium diagram and has been called "inverse segregation."

Jan 10, 1926

By K. Huessener

This paper attempts a survey of the principles involved in the combustion of blast-furnace gas in boilers and stoves. I do not expect to be able to give much information which is actually new, since the laws and methods of calculation pertaining to this problem are contained in a number of handbooks; but, so far as I am aware, they have nowhere been treated exclusively with reference to this one problem of gas economy. The road which I follow is less that of strictly scientific research than that of the practical engineer, faced by operation problems which require a quick solution by easily accessible means without a prolonged search in scientific handbooks. For this purpose I give a number of tables and diagrams, as well as the results of many years1 practical working experience as combustion engineer, which I trust will prove useful to my readers. HlSTORICAL Considering the tremendous efforts made during the last 15 years to increase the efficiency of all kinds of power plants, it is highly surprising that until a comparatively very recent period, progress in the economical combustion of blast-furnace gas has been so slow, The explanation generally put forth, that fuel has been so cheap that it was hardly worth while to bother about this economy, will not hold good, for the greatest trouble was taken to improve the combustion of coal and to reduce the consumption of steam, The most plausible explanation appears to be the general impression, held as an accepted fact, that gas, especially hot, uncleaned, blast-furnace gas, was not a good boiler fuel. Many managers of high repute had tried unsuccessfully to improve the conditions of its use, and the dictum went forth that efficiencies of over 60 per cent., particularly with high loads, were impossible. This was the situation not only in the United States, with very cheap fuel, but also in Europe, where fuel prices are twice and three times as high.

Jan 1, 1916

By H. H. Uhlig

In our study of the mechanism of and the prevention of corrosion in stainless steels, it was considered of fundamental importance to obtain knowledge of the surface structure of such alloys. If corrosion resistance is due to a self-healing oxide layer, which like a paint film protects the underlying metal, it would be obviously relevant were the effort made to make the film less permeable and more adherent; for example, the surface might be expected to respond to an anodizing process, which is found successful in increasing the film thickness and corrosion resistance of aluminum. However, if passivity and corrosion resistance of stainless steels are due to another cause, the attack of the problem would follow another path. One of the most effective techniques for studying passivity and corrosion tendency is the measurement of the electrochemical potential. Not only can one determine by potential measurements whether a metal is active or passive, but also one can determine the degree of passivity and rate of transformation of passivity with time. Chemical media that build up or destroy passivity when in contact with the steel can also be classified by potential measurements. Something can be learned, too, of the effect of alloy additions such as molybdenum to 18-8, known to decrease corrosion of the alloy in chloride solutions. A study of alloys in previous investigations has sometimes included data on the electrochemical potentials. Tammann and Sotterl measured the electrochenlical potentials of alloys of iron-molybdenum and iron-chromium and reperted the critical concentration of molybdenum or chromium at which passivity initiates. Strauss2 made similar measurements for the iron-chromium system. The electrochemical potential3 has also been used to indicate carbide precipitated 18-8. In 18-8, heat-treated to precipitate carbide, active metal exists at the region of the grain boundaries, contrasted with passive metal within the grains, the active metal accounting for a resultant active potential. Several

Jan 1, 1940

By H. H. Uhlig

In our study of the mechanism of and the prevention of corrosion in stainless steels, it was considered of fundamental importance to obtain knowledge of the surface structure of such alloys. If corrosion resistance is due to a self-healing oxide layer, which like a paint film protects the underlying metal, it would be obviously relevant were the effort made to make the film less permeable and more adherent; for example, the surface might be expected to respond to an anodizing process, which is found successful in increasing the film thickness and corrosion resistance of aluminum. However, if passivity and corrosion resistance of stainless steels are due to another cause, the attack of the problem would follow another path. One of the most effective techniques for studying passivity and corrosion tendency is the measurement of the electrochemical potential. Not only can one determine by potential measurements whether a metal is active or passive, but also one can determine the degree of passivity and rate of transformation of passivity with time. Chemical media that build up or destroy passivity when in contact with the steel can also be classified by potential measurements. Something can be learned, too, of the effect of alloy additions such as molybdenum to 18-8, known to decrease corrosion of the alloy in chloride solutions. A study of alloys in previous investigations has sometimes included data on the electrochemical potentials. Tammann and Sotterl measured the electrochenlical potentials of alloys of iron-molybdenum and iron-chromium and reperted the critical concentration of molybdenum or chromium at which passivity initiates. Strauss2 made similar measurements for the iron-chromium system. The electrochemical potential3 has also been used to indicate carbide precipitated 18-8. In 18-8, heat-treated to precipitate carbide, active metal exists at the region of the grain boundaries, contrasted with passive metal within the grains, the active metal accounting for a resultant active potential. Several

Jan 1, 1940

By J. D. Shaw, E. B. Gebert, D. O. Noel

It is, of course, expected that manufacture of the various metal powders should involve numerous methods adapted to the specific characteristics of the metals themselves. Several methods for powdering a particular metal may be available, but the physical characteristics of the powder as produced by the several methods may be quite different. In the final analysis, the application of the metal powder dictates the physical properties that the metal powder must possess, and this, to a very large extent, will determine which of several possible methods of manufacture is adopted. Sometimes powder of the same metal is produced by more than one method, each powder having specific characteristics that make it particularly suitable for its application. For purposes of classification, the various methods of powdering metals can be grouped as follows: 1. Machining. 2. Milling (by ball mills, stamps, attrition mills, etc.). 3. Shotting (pouring molten metal into water, air, etc.). 4. Granulation (by stirring molten metal while solidifying). 5. Atomizing (disintegrating by steam, compressed air, etc.). 6. Condensation of metal vapor. 7. Reduction of oxide powders. 8. Chemical precipitation. 9. Electrolytic deposition. 10. Sintering (for producing alloy powders). 11. Formation of an alloy followed by dissolving or otherwise removing one of the alloying constituents. Machining Turnings, cuttings, filings, etc., are, of course, produced as by-products in machine work of various kinds, and find certain applications as metal powders. For example, iron powder so produced is used extensively as a reducing or precipitating agent and as a constituent in certain hard-finish cements.

Jan 1, 1938