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By AIME AIME

ON the morning of Monday, Nov. 9, 1936, two motorcycles, with sirens screeching, - escorted a procession of 70 automobiles from the Colonia Railway Station in Mexico City to the Hotel Geneve. Riding in' the cars were just over 200 visitors- members of the A.I.M.E. and their guests. They had come, via St. Louis, in two special trains from 24 different states for the 146th General Meeting of the Institute. During the morning they and 200 others, who had come from the United States by automobile or from various cities and mining camps in Mexico, duly registered with !efficient Mme. Irma Ordoiiez de Obregon and her assistants. Then started a week of strenuous but delightful activity that will never be forgotten by the participants. They were to cover more than 500 miles by automobile, always with a motor escort, and often

Jan 1, 1937

By T. T. Chen, P. Pint

Based on the mineralogy, phase characteristics and compositions of the smelter feed, the smelter products and the smelter wastes, the sources and distributions of mercury and arsenic in the Afton copper smelter, Kamloops, British Columbia have been determined. Of the total mercury In the feed, approximately 33% is in solid solution in tennantite, 51% is in native copper and 16% occurs as mercurian silver. Arsenic in the feed occurs mainly as tennantite. Under current smelting conditions, 99.6% of the total mercury In the feeds enters the off-gas cleaning system. From this off-gas, about 1% of the total mercury, occurring as dust, is recirculated to the flotation concentrate; 4.6% of the total mercury is contained in SO2 scrubber sludge which is discharged to tailings. Approximately 78% of the total arsenic in the smelter reports in the copper products; 20% is incorporated in the dust and slag which are subsequently recirculated to the mill. Only 1.8% is rejected as scrubber sludge, and less than 0.2% 1s released to the mercury scrubber.

Jan 1, 1984

By B. Silliman

The experiments detailed by Dr. Hunt,* having demonstrated the fact that the copper contained in the "clay ore" of Jones's Mine, was rendered completely soluble in the bath of ferrous chloride, used in the Hunt and Douglas process, after heating in contact with carbonaceous matter in a close vessel, I set myself to devise a form of muffle furnace adapted to the treatment of large quantities of these and similar ores by a continuous process. The result is shown in the diagrams on Plate X, reduced from the working drawings, after which this furnace was built early in 1876, at Phœnixville, by the Chemical Copper Company on their works at this place. The peculiar character of this ore determined the form, dimensions, and position, with reference to charging and discharging of these muffles. The ore arrived from the mine with from 20 to 25 per cent. of moisture, and when dried at 21o F., or more slowly at lower temperature, it falls to a light incoherent powder, with occasional lumps of undecomposed rock. In this condition it is readily mingled with coal-dust or any like reducing agent, and requires no other preparation for the muffle than the use of the shovel, to mix it well with the reducing agent. As it is a remarkably good non-conductor of heat, it was obvious that the mass, to be heated through in a reasonable time, must not be too thick, while the weight of the mass must be sustained in a way to avoid undue strain upon the walls of the muffle. These walls must be as thin as practicable, to favor the more rapid transmission of heat, and must, therefore, be so constructed as to admit of being stayed on the sides at frequent intervals to resist the lateral thrust of the very mobile mass of pulverulent ore, which, for obvious reasons, must be charged at the top and drawn from the bottom of each chamber. These considerations led to the form adopted, viz., two vertical muffles, standing upon very strong bridge tiles, seen in longitudinal section, on the line E, F, and in plan in Fig. 3, on the same plane. (Plate X.) The vertical section of the muffle is seen in Fig. 4, drawn in the plane G, H, of the longitudinal section, Fig. 6, which is the key to all sections. The walls of the muffles are built of the best firebrick, very care-

By G. E. Archie

THE usefulness of the electrical resistivity log in determining reservoir characteristics is governed largely by: (I) the accuracy with which the true resistivity of the formation can be determined; (2) the scope of detailed data concerning the relation of resistivity measurements to formation characteristics; (3) the available information concerning the conductivity of connate or formation waters; (4) the extent of geologic knowledge regarding probable changes in facies within given horizons, both vertically and laterally, particularly in relation to the resultant effect on the electrical properties of the reservoir. Simple examples are given in the following pages to illustrate the use of resistivity logs in the solution of some problems dealing with oil and gas reservoirs. From the available information, it is apparent that much care must be exercised in applying to more complicated cases the methods suggested. It should be remembered that the equations given are not precise and represent only approximate relationships. It is believed, however, that under favorable conditions their application falls within useful limits of accuracy.

Jan 1, 1942

By W. J. Taylor

IN making heating gas with anthracite coal for roasting ore during the past few years, I hare tried many forms of gas generators. So far, the most successful and satisfactory one has been what we call a fluxing producer, which is simply a small cupola or blast furnace, in which we charge with the coal, say, 30 or 40 per cent. of basic blast-furnace cinder, to unite, when melted, with the ash or earthy matter in the coal, and carry it off as cinder. The producer we have in use at Chester, N. J., has pore of the lines of a blast furnace than a cupola, the hearth being 24 inches diameter and 24 inches high. It then enlarges on an angle of about 25 degrees from a perpendicular to 4 feet, and then is drawn into 3 feet on top ; total height, 12 feet. We use one water coil-tuyere 12 inches above the bottom, and blow through a 11/2-inch nozzle. The depth of coal above the tuyere averages about 6 feet. The producer. is blown with

Jan 1, 1881

By J. T. Mackenzie

Henry Marion Howe, in whose memory we are gathered together, was one of the great thinkers who develop from time to time to whom is given the rare gift of synthesis. Analysis is given to few, but synthesis, the ability to show the relation of all parts to each other and thus to give a clear picture of the whole, is reserved for the very few. Analysis can be achieved by honesty, intelligence, and industry, but synthesis is only given to genius. Professor Howe's crowning achievement is the picture of the whole iron-carbon series shown in Fig. I, which places steel, malleable, gray iron, mottled and chilled irons in their proper relation to each other and shows the essential unity of the series. Perhaps his best statement of the case is found on page go of the Metallography of Steel and Cast Iron in these words: " Each member of the gray cast-iron series consists of the metallic matrix approximately equivalent to that member of the steel-white-cast-iron series to which it corresponds in percentage of combined carbon with its continuity broken up—by masses of graphite ..." Apparently he had taken considerable interest in this idea around the turn of the century, for he refers to a discussion at the Franklin Institute in I900 in which he said: "Though many others had probably conceived this relation between the steels and cast irons, it was here enunciated for the first time, so far as I know. It was received with great incredulity." The concept was explained in some detail in a paper on "The Constitution of Cast Iron" presented before the A.S.T.M. in 1902 when Professor Howe was retiring president of that young society. In the discussion Dr. Sauveur stated that he was "very well acquainted with Professor Howe's theory of the constitution of cast iron," and went on to say that while he "shared it to the fullest extent, some foundrymen . . . claim cast iron is a metal entirely different from steel . . . that steel and cast iron have very little in common, and that therefore the knowledge gained in the study of steel is of little or no value in the study of cast iron." Dr. Moldenke, in discussing the same paper, said he had been working on the same theory for 12 years but he laid no claim to publication. Discussing the difference in the micro-structure of the metallic matrix, Professor Howe pointed out that "such minor structural differences are indeed to be expected, because of the difference in the conditions under which these constituents are generated. "One difference in these conditions is that the steel of most micrographs has been either forged or at least treated thermally in such a way as to give a new structure radically different from that which formed during the initial solidification, whereas the cast irons have not. Hence what we see in the steels is a transformation structure, but in the cast irons a solidification structure. By giving the cast

Jan 1, 1944

By J. T. Mackenzie

Henry Marion Howe, in whose memory we are gathered together, was one of the great thinkers who develop from time to time to whom is given the rare gift of synthesis. Analysis is given to few, but synthesis, the ability to show the relation of all parts to each other and thus to give a clear picture of the whole, is reserved for the very few. Analysis can be achieved by honesty, intelligence, and industry, but synthesis is only given to genius. Professor Howe's crowning achievement is the picture of the whole iron-carbon series shown in Fig. I, which places steel, malleable, gray iron, mottled and chilled irons in their proper relation to each other and shows the essential unity of the series. Perhaps his best statement of the case is found on page go of the Metallography of Steel and Cast Iron in these words: " Each member of the gray cast-iron series consists of the metallic matrix approximately equivalent to that member of the steel-white-cast-iron series to which it corresponds in percentage of combined carbon with its continuity broken up—by masses of graphite ..." Apparently he had taken considerable interest in this idea around the turn of the century, for he refers to a discussion at the Franklin Institute in I900 in which he said: "Though many others had probably conceived this relation between the steels and cast irons, it was here enunciated for the first time, so far as I know. It was received with great incredulity." The concept was explained in some detail in a paper on "The Constitution of Cast Iron" presented before the A.S.T.M. in 1902 when Professor Howe was retiring president of that young society. In the discussion Dr. Sauveur stated that he was "very well acquainted with Professor Howe's theory of the constitution of cast iron," and went on to say that while he "shared it to the fullest extent, some foundrymen . . . claim cast iron is a metal entirely different from steel . . . that steel and cast iron have very little in common, and that therefore the knowledge gained in the study of steel is of little or no value in the study of cast iron." Dr. Moldenke, in discussing the same paper, said he had been working on the same theory for 12 years but he laid no claim to publication. Discussing the difference in the micro-structure of the metallic matrix, Professor Howe pointed out that "such minor structural differences are indeed to be expected, because of the difference in the conditions under which these constituents are generated. "One difference in these conditions is that the steel of most micrographs has been either forged or at least treated thermally in such a way as to give a new structure radically different from that which formed during the initial solidification, whereas the cast irons have not. Hence what we see in the steels is a transformation structure, but in the cast irons a solidification structure. By giving the cast

Jan 1, 1944

By Evan Evans

IT is appropriate to evaluate 1947 in review as a year of a peacetime record production of about 676,000,000 tons of coal (anthracite and bituminous), closely approaching the extraordinary wartime output in 1944. Considering the general price-wage inflation, it is in point to note that the coal industry sustained the highest wages paid to workers in any major industry, but that coal prices at wholesale levels have risen much less percentage wise than the average for all commodities. The sellers' market continues to prevail. In addition to serving our own country's enormous needs, our coal industry is exporting extraordinary tonnages overseas. This unusual export demand is likely to continue for a while. Moreover, the demand in Europe for American coal mining machinery is a real tribute to the management efficiency of our modern mechanized coal industry. Competitively, the petroleum industry is concerned over its long-term supply, and already a synthetic fuels industry is being publicly advocated. In due time coal and lignite are bound to be

Jan 1, 1948

By J. C. Kerkering, P. M. Daling

This paper discusses a study performed to evaluate the feasibility of transferring formal system safety assessment technology to the mining industry. A representative listing of formal techniques was evaluated to select the most useful methods for the mining industry to implement. Criteria for selecting methods included the interests, needs, and requirements of mine safety officials. This paper describes one of the selected methods, preliminary hazards analysis (PHA), and illustrates the analysis procedure for a mining example. This study also includes an assessment of the adaptability of selected methods to a user-interactive computer system for use by mine safety personnel. This paper includes a description of a conceptual computerized PHA-type safety program that facilitates performance of the safety analysis and can accommodate updates and revisions as necessary.

Jan 1, 1983

By R. D. Carnahan, J. E. White

A study of dispersion strengthening in TD-Nickel (nickel plus 2 vol pct Tho2) was conducted employing microstrain techniques at ambient room temperature. It was found that optimum strength was due primarily to the incorporation of stored energy developed by a variety of thermal-mechanical treatments. The relatively low strength of the recrys-tallized condition implies that the dispersed particles themselves offer only token resistance to deformation. The development of resistance to large-scale recovery or recrystallization at temperatures near the melting point requires a more extensive sequence of strain-anneal cycles than does the development of optimum strength. A micro-Bauschinger effect was observed which appears to be related to the lattice resistance to the movement of free dislocations. The effect was nearly identical to that in pure nickel indicating that the presence of the dispersed phase and considerably increased dislocation density (stored energy) only alters the number or effectiveness of barriers. THE early stages of deformation of engineering materials can be conveniently studied by utilizing strain-gage techniques which permit resolution of strains less than 5 X 10-7 in. per in. for testing in four-point bending (Carnahan and white1). The present investigation, part of a continuing study on the very early stages of deformation, was designed to reveal the true role of a dispersed phase in promoting high strength in a commercially available dispersion-strengthened alloy. Although this technique has been used for some time to study microdeformation in pure metals and alloys, it has just recently received attention as a means of investigating dispersion strengthening. Studying the very early stages of deformation in alloys which depend upon a finely dispersed inert phase for strength may prove to be a very important method for a better understanding of these materials. It is essential to obtain considerable clarification of actual dislocation movement and the kinds of deformation barriers which exist before optimum properties can be designed into this type of material with any degree of confidence. Considerable research on a variety of dispersion-strengthened materials has resulted in two different schools of thought regarding the strengthening mechanism. One faction2-4 favors the idea that the particles themselves resist the motion of dislocations. The criterion for yielding is the fracture of the dispersed second-phase particles due to an array of piled-up dislocations. Other invesfigators5-a have shown that particles are effective primarily by allowing a greater buildup of stored energy or dislocation density through thermal-mechanical treatments in the composite than the pure matrix material. The particles themselves, then, are not exclusive obstacles, but the complex network of particles, dislocation tangles, subboundaries, and grain boundaries are strength determining. The development of such a complex dislocation network in SAP has been studied recently in some detail by Goodrich and Ansell. The ability of dispersion-strengthened alloys to resist softening or recrystallization is also of considerable importance; however, the criteria for maximum stability may not necessarily be those for maximum strength. In this study, in addition to the evaluation of the microstrain properties of TD-Nickel, it is felt that considerable clarification of the true dependence of strength and stability on the dispersed phase is shown. I) MATERIAL AND PROCEDURE TD-Nickel is a dispersion-strengthened alloy developed by the E. I. DuPont de Nemours Co., which contains 2 vol pct thoria (Tho2) in a pure-nickel matrix. The average ThO2 particle size is approximately 0.1 p and the interparticle spacing is less than 1 u. The material was supplied by DuPont in two conditions: hot-extruded bar stock, and stress-relieved cold-rolled sheet 0.025 in. in thickness. The bar was extruded at 2200°F from a cold-pressed and sintered billet. The sheet stock was prepared from the extruded material by a process involving ten or more 50-pct cold reductions by rolling with intermediate anneals at 1800° to 2000°F. Test specimens used in this study were prepared in the form of rectangular parallelepipeds measuring 0.375 by 1.375 in. in thicknesses ranging from 0.025 to 0.040 in. Samples prepared from sheet and extruded stock were mechanically polished before heat treatment and were handled with extreme

Jan 1, 1964

AS you have been able to observe, I have up to the present demonstrated as, well as I knew how in writing the art of casting- and the methods of making moulds and of baking them; then the arrangements of the furnaces for melting the materials, including those made for melting by reverberation of flames or with bellows and charcoal, and the hearth, basket, ladle, and other similar instruments customary in such operations. Now I wish to show you how to bring to their conclusion the works for which these instruments are made, and show

Jan 1, 1942

By AIME AIME

ON MAY 22 the American Institute of Mining and Metallurgical Engineers will commemorate the sixtieth anniversary of its founding at Wilkes- Barre, Pa., in May, 1871. The Directors have transferred the May meeting of the Board to Wilkes-Barre, and the Pennsylvania Anthracite Section has invited as many members of the Institute as can to be present at this time and to join with their fellow-engineers at Wilkes-Barre in the inspection trip through a portion of the anthracite district that has been planned. Ac- cess to Wilkes-Barre is easy, from nearby points, over excellent automobile roads, or by train. The distance from New York is only about 140 miles. , It is hoped to engage a special car for those travelling by train from New York, which will leave the Pennsylvania Station over the Lehigh Valley Railroad at 11:50 p.m., arriving in Wilkes-Barre the next morning. Return can be made from Wilkes-Barre by sleeper the same evening, arriving in New York Saturday morning. Other trains are available for those who prefer a daylight journey.

Jan 1, 1931

By Alan M., Bateman

MR. JORALEMON'S dispassionate discussion of this subject in TECHNICAL PUBLICATION 340 of the Institute shows clearly some of the failures and successes of geology in the discovery of ore deposits. He forces us to recognize, with humility, that chance has played a greater part than geology in the recent discovery of several great copper deposits. I think, however, he wrongly ascribes to unexpected or chance discovery some deposits that were found as a direct result of geological investigation. I refer to the Rhodesian copper deposits,, particularly Roan Antelope and Mufulira, both mentioned by him as having been found by chance. Also,. I think Mr. Joralemon's paper, inadvertently, does not- give the proper credit for the early recognition of the possibilities of these deposits. I feel sure that Mr. Joralemon and the gentlemen given credit by him will welcome any further information on this subject that will throw light on what will some day- be of. historical interest and importance. Consequently, I should like to set forth some additional data that throw light on who should receive the most credit, and' to indicate that, in my opinion, sound. geological reasoning and not chance is to be, credited for the development of the. Roan Antelope and Muf ulira mines.

Jan 1, 1931

By H. Herbert Hughes

ECONOMISTS have predicted that the present business depression ultimately may pay big dividends to industry through the cumulative savings resulting from technical improvements and merchandising advances that might never have been developed under normal conditions. Waste prevention is a sound medicine for economic ills. In theory, this prescription may be applied not' only to raw materials, but also to labor, fuel, over- head, and other phases of production. Actually, how- ever, regardless of the efficiency of operating practices, waste is inevitable in the production of many commodities. The problem then becomes one of profitable utilization of waste rather than prevention.

Jan 1, 1932

By John B. Pearse

IN view of the great importance of accurate knowledge respecting the chemistry of iron and steel, as related to their physical properties, I come before you with a paper showing the great mass of work which has been heretofore done on the subject. I have tabulated the more important data I bring at this time, so as to draw out the results clearly. This information is accessible to all who will seek for it. I have made it the basis of my own practice throughout, and such knowledge is undoubtedly the only foundation, for the successful practice of metallurgy. As is well known the ordnance corps of our army, after 1841, made exhaustive experiments on the properties of cast-iron. The investigations were undertaken in order to obtain necessary information on the reorganization of the corps. I wish to call your attention to the results obtained by a comparison of the chemical and physical properties of cast-iron for guns, to describe certain characteristic peculiarities of steel, and to give a brief history of the chemical work relating to carbon in iron. The Reports on Experiments on the Strength and other Properties of Metals for Cannon, published by H. Carey Baird, Philadelphia,

Jan 1, 1876

By John B. Pearse

In view of the great importance of accurate knowledge respecting the chemistry of iron and steel, as related to their physical properties, I come before you with a paper showing the great mass of work which has been heretofore done on the subject. I have tabulated the more important data I bring at this time, so as to draw out the results clearly. This information is accessible to all who will seek for it. I have made it the basis of my own practice throughout, and such knowledge is undoubtedly the only foundation for the successful practice of metallurgy. As is well known the ordnance corps of our army, after 1841, made exhaustive experiments on the properties of cast-iron. The investigations were undertaken in order to obtain necessary information on the reorganization of the corps. I wish to call your attention to the results obtained by a comparison of the chemical and physical properties of cast-iron for guns, to describe certain characteristic peculiarities of steel, and to give a brief history of the chemical work relating to carbon in iron. The Reports on Experiments on the Strength and other Properties of Metals for Cannon, published by H. Carey Baird, Philadelphia,

By Frederick Mark Becket

DOCTOR Albert Sauveur, distinguished scientist and Honorary Member of this Institute, predicted in the first Howe Memorial Lecture that the privilege of delivering this annual address would be considered a highly significant honor. The intervening years have well borne out Sauveur's prophecy. I wish to assure the American Institute of Mining and Metallurgical Engineers that I also deeply appreciate this honor, recognizing at the same time the present and even more the future responsibilities with which it is accompanied. Several of the previous lecturers had the good fortune to attend the classes of Professor Howe and to work in his laboratories. I was similarly favored, although in my instance and to my great regret the period was all too short. However, Howe's book, published in 1903, "Iron, Steel and Other Alloys," afforded me abundant opportunity to continue these studies. How well I remember the inspiration I derived from this famous book by Howe, the metallurgical master, pioneer, and educator! Remembering that Professor Howe contributed numerous papers to The Metallographist, a magazine supported from a technical point of view by the world's pioneers in metallography, I was curious a few days ago to learn the nature of Howe's early contributions to this magazine. The first paper by Howe in the first year of The Metallographist (1898) dealt with the allotropic theory; the second also treated of allotropy, and I quote the first sentence of that paper: The allotropic theory of the hardening of steel may, like so many other important theories, have to be accepted or rejected not on direct proof or disproof, but on the accumulation of circumstantial evidence for or against it. Howe's ability to stimulate others by his deep understanding and clarity of expression was truly remarkable; but just as striking was his intuitive judgment concerning the implications of metallurgical data in the arts and sciences. It therefore seems fitting that this lecture comprise a broad treatment of the subject chosen, rather than a closely documented thesis on any one phase of the problem; that in it attention be focused

Jan 1, 1938

By Frederick M. Becket

DoctoR Albert Sauveur, distinguished scientist and Honorary Member of this Institute, predicted in the first Howe Memorial Lecture that the privilege of delivering' this annual address would be considered a highly significant honor. The intervening years have well borne out Sauveur's prophecy. I wish to assure the American Institute of Mining and Metallurgical Engineers that I also deeply appreciate this honor, recognizing at the same time the present and even more the future responsibilities with which it is accompanicd. Several of the previous lecturers had the good fortune to attend the classes of Professor Howc and to work in his laboratories. I was similarly favored, although in my instance and to my great regret the period was all too short. However, Howe's book, published in 1903, "Iron, Steel and Other Alloys," afforded me abundant opportunity to continue these studies. How well I remember the inspiration I derived from this famous book by Howe, the metallurgical master, pioneer, and educator! Remembering that Professor Howe contributed numerous papers to The Metallographist, a magazine supported from a technical point of view by the world's pioneers in metallography, I was curious a few days ago to learn the nature of Howe's early contributions to this magazine. The first paper by Howe in the first year of The Metallographist (1898) dealt with the allotropic theory; the second also treated of allotropy, and I quote the first sentence of that paper: The allotropic theory of the hardening of steel may, like so many other important theories, have to be accepted or rejected not on direct proof or disproof, but on the accumulation of circumstantial evidence for or against it. Howe's ability to stimulate others by his deep understanding and clarity of expression was truly remarkable; but just as striking was his intuitive judgment concerning the implications of metallurgical data in the arts and scienees. It therefore seems fitting that this lecture comprise a broad treatment of the subject chosen, rather than a closely documented thesis on any one phase of the problem; that in it attention be focused

Jan 1, 1938

By Frederick M. Becket

DoctoR Albert Sauveur, distinguished scientist and Honorary Member of this Institute, predicted in the first Howe Memorial Lecture that the privilege of delivering' this annual address would be considered a highly significant honor. The intervening years have well borne out Sauveur's prophecy. I wish to assure the American Institute of Mining and Metallurgical Engineers that I also deeply appreciate this honor, recognizing at the same time the present and even more the future responsibilities with which it is accompanicd. Several of the previous lecturers had the good fortune to attend the classes of Professor Howc and to work in his laboratories. I was similarly favored, although in my instance and to my great regret the period was all too short. However, Howe's book, published in 1903, "Iron, Steel and Other Alloys," afforded me abundant opportunity to continue these studies. How well I remember the inspiration I derived from this famous book by Howe, the metallurgical master, pioneer, and educator! Remembering that Professor Howe contributed numerous papers to The Metallographist, a magazine supported from a technical point of view by the world's pioneers in metallography, I was curious a few days ago to learn the nature of Howe's early contributions to this magazine. The first paper by Howe in the first year of The Metallographist (1898) dealt with the allotropic theory; the second also treated of allotropy, and I quote the first sentence of that paper: The allotropic theory of the hardening of steel may, like so many other important theories, have to be accepted or rejected not on direct proof or disproof, but on the accumulation of circumstantial evidence for or against it. Howe's ability to stimulate others by his deep understanding and clarity of expression was truly remarkable; but just as striking was his intuitive judgment concerning the implications of metallurgical data in the arts and scienees. It therefore seems fitting that this lecture comprise a broad treatment of the subject chosen, rather than a closely documented thesis on any one phase of the problem; that in it attention be focused

Jan 1, 1938

By T. MacDONALD

ATHOUGH flotation has been a commercial process for over twenty years, the last two years have witnessed a sudden and phenomenal increase in our knowledge of how to separate minerals heretofore not considered amenable to flotation at all. As remarked by Professor Locke in the January issue. "Either commercial or laboratory flotation is reported on zircon, ilmenite, carnotite, kyanite, scheelite, chromite, fluorite, feldspar, cassiterite, wolframite, barite, and clay. Attractive patents on soap flotation are U. S. Nos. 2,000,656 and 2,040.187. A survey by Ralston in the February E. & M. J. adds many other minerals to this impressive list. The simple but pregnant fact is that any mineral can be coated, directly or indirectly, with a water-repellent coating, and since this is true, it follows that any mineral can be floated. Fundamentally, this is no new discovery, where, for instance, is the mineral that cannot he washed from a pair of dirty hands by means of soap and water, given the absence of refractory greases or oils which would have no proper place in flotation ?

Jan 1, 1937