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By Masayuki Otagawa

THE mining methods adopted in Japanese mines are less known to the mining world than those of other countries, owing to the geographical remoteness, but they present many features of interest to mining engineers. The Ashio copper mine is at the village of Ashio, in Tochigiken, about 109 mi. (175 km.) from Tokyo by the Imperial Government railroad. The area of the concession owned by the Furukawa Mining Co. is 5000 acres (5023 ha.). The mine was formerly divided into three, viz.. Honzan, Kotaki, and Tsudo, which are distant 3 mi. (4.8 km.) from each other as shown in Fig. 1. However, in 1914, when the writer was general manager, the three mining plants were amalgamated into one with the result of simplifying the working projects and increasing the operat-ing efficiency. The mine was visited-by the Institute party in November, 1911, when Mr. K. Inouye was the general manager. Shortly afterward, the writer was appointed manager, and, in 1915, he was succeeded by Dr. K. Asano. At the end of 1917, Mr. K. Kibe became general manager and, after two years, was succeeded by the present manager, Mr. I. Sugimoto-. For some time Dr. J. Kojima was acting general manager. It is needless to say that the gentlemen mentioned are all members of the Institute, as is also Baron T. Furukawa, president of the company. Since the discovery of the enormous masses, called "kajika" or "bullhead" deposits; which the writer has described elsewhere,' the mining methods have been varied to meet the different conditions presented by these deposits.

Jan 2, 1922

By E. C. Wright

FOR many years the cost of making pig iron and steel in the Birmingham district has been about the lowest in the United States. The close proximity of the important raw materials such as coal, iron ore, limestone, and the large available scrap supply made it possible to assemble all of the important ingredients necessary for steel- making with only nominal costs for transportation. Both iron ore and coal were being mined in this district at one time for about $1 per ton from underground operations. At that time mining wages were low everywhere and the labor rate in the South was considerably below that of other mining districts. This situation persisted until the emergence of labor unions as an economic and political force, emigation of southern labor to northern plants, and continued growth of industry in the South in the years following the depression of 1932. Since that time union organizing of miners and steel workers throughout the nation has increased labor costs in mining and steelmaking. This influence has been felt particularly in underground mining operations since the proportion of labor cost to total cost is still high. The previous advantage in basic labor rate in the South has been almost entirely eliminated by the equalization of labor rates in basic industries by national unions. Since 1945 these influences have been especially noticeable in increasing the cost of mining coal and iron ore in the South. The northern steel districts are still being largely supplied with iron ore from the Minnesota open-pit mines and the cost of this ore has not increased nearly as much as the cost of ore obtained from underground mines in Birmingham. A similar situation exists in coal mining; the thinner seams in Alabama are not so amenable to mechanization as the northern mines and, as a result, the output per man-day in southern mines is only about three tons of coal as compared to five or six tons per man-day in the large captive mines of West Vir-

Jan 1, 1950

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Jan 1, 1946

By Danforth R. Hale

Minerals for electronic and optical uses divide easily into two sections: (1) quartz and (2) minerals other than quartz. Quartz Quartz, having a great usefulness discovered by the radio communication enthusiasts about 1918, has become a subject of amazingly expanded interest in the U.S. over the past decade as a man-made mineral and a $3 million crystal-growing business. An economic summary of the commercial growing of quartz crystals has a place in a handbook directed to the mineral engineering industry when it is remembered that quartz crystals have long been an important commercial mineral, and that the raw material for “cultured quartz”- that is to say, quartz crystals grown through the ingenuity of man-is still natural quartz. Nearly all the natural crystals come from Brazil. The larger pieces which meet rigorous standards of quality are used for electronic and, to a lesser extent, optical components. Smaller pieces and fragments are used for vitreous silica. The need for high quality material in quantity led to U.S. government-sponsored research programs in the 1940s that have resulted in the factory growing of beautiful crystals of prescribed shape, size, and quality. The development of the cultured quartz crystal is typical of man's success in adapting the product of the mine to increasingly sophisticated uses. A remarkable achievement perhaps, but foreshadowed by experiments in 1908 by Giorgio Spezia (1908), an Italian geologist studying the relative effects of temperature and alkaline environment on the solubility of quartz. Modern radio equipment is most often controlled as to frequency by the presence in the circuit of a separately added "crystal"-the 1918 discovery responsible for the existence and growth of the quartz industry. The "crystal" is quartz, but this component is a carefully oriented and prepared slice from a crystal, but not a crystal as recognized by a rock hound or seen in a museum. How quartz operates to control frequencies is not a proper subject for a handbook on industrial minerals, and references should be consulted (Cady, 1964; Mason, 1964). Quartz belongs to that class of materials called dielectrics: those that do not conduct an electric current but permit electric fields to exist and act across them. Quartz shows the "piezo-electric effect," which means that when a quartz plate is mechanically deformed against its natural stiffness, one of its surfaces becomes negatively charged, the other, positively charged. When the plate is released from the stress quickly, the charges disappear as the plate regains its original shape, but because of mechanical momentum the plate deforms in the opposite direction (to a lesser amount) and the surfaces correspondingly become charged in the opposite direction. By coating the two surfaces thinly with metal and attaching flexible wires, these charges may be brought into an electronic circuit. If the surfaces are suddenly electrically charged by movement of current through the wires, the "converse piezoelectric effect" occurs -the plate deforms. Carry the thought further and it is realized that an alternating current flowing through the wires responds to the mechanical oscillation of the plate and is keyed to this oscillation. By controlling the thickness of the plate its mechanical vibration frequency can bevaried through a wide range. One type of quartz plate, called the AT-cut, having a precisely defined orientation with respect to the crystallographic axes of the crystal, vibrates on a microscopic scale much as a book would deform when placed flat on a table and the top cover moved parallel back and forth with the hand. There are at least 17 other orientations which have been studied, some of

Jan 1, 1975

By R. B. Mears, G. F. Sagar, R. H. Brown

There are well recognized procedures for determining the various tensile, fatigue, and other mechanical properties of the common structural materials. This makes it possible for engineers to design structures of various materials which have adequate initial strength to stand the stresses to which they are subjected in service. There is also considerable general information about protective measures suitable for protecting the usual structural materials from the effects of ordinary environments. However, often insufficient quantitative information is available on the combined effects of stress and corrosion to permit the designer satisfactorily to appraise the structure from the stress-corrosion standpoint. This situation is further complicated by the fact that the stresses causing stress¬corrosion failures are usually not the design stresses but rather the residual forming and assembly stresses which are generally of unknown magnitudes. Thus, tests which will rapidly evaluate the susceptibility of materials to stress-cor¬rosion failures are extremely useful. Of particular value are tests which can be applied to built-up structures as well as to simple specimens, since, as mentioned above, residual stresses often are caused by fabricating procedures and assembly operations. The present paper contains

Jan 1, 1945

By John Hays, Hammond

IT is both a pleasure and an honor to be a guest of the Institute and I thank you, Mr. President and fellow-members, for giving. me the opportunity of meeting you this evening. My esteemed friend, President Smith, has requested me to do a bit of "reminiscing" as to the earlier years of my career as a mining engineer, which has now covered a period of fifty years. Let me reassure you by promising that my narrative will not include all the experiences I have had over that long period. You will, I trust, pardon what might seem egotistical but I do not see how a personal narrative could well be otherwise.

Jan 1, 1928

CONTENTS PAGE Rae, Colin C.-A Possible Origin of Oil. Discussed by S. Linker, Colin C. Rae... 2 Cottingham, Kenneth.-Subsurface Conditions on Portion of Arches Fork Anticline. Discussed by David B. Reger 6 Moyer, W. Irwin.-Time to Pay Out as a Basis for Valuation of Oil Properties. Discussed by H. J. Smith 9 Pogue, Joseph E.-Future Demands on Oil Industry of United States. Discussed by James O. Lewis 11 J. J. Walsh.-Coa-lmine Ventilation. Discussed by W. B. Daly, J. J. Walsh, R. R. Sayers, H. H. Stock, George S. Rice, James W. Paul, D. Harrington, T. D. Thomas 15 Longyear, Robert Davis.-Diamond-drill Sampling Methods. Discussed by Ira B. Joralemon, J. J. Rutledge, E. C. Harder 19 Joralemon, Ira B.-Sampling and Estimating Disseminated Copper Deposits. Discussed by J. Parke Channing, John E. Hodge, E.E. Hunner, B. B. Gottsberger, W. Y. Westervelt, W. O. Hotchkiss 20 Boericke, W. F.-Sampling and Estimating Zinc and Lead Orebodies in Mississippi Valley. Discussed by J. Parke Channing, Arthur Thacher 24 Daly, W. B. and Linforth, F. A.-Organization of Mine Sampling at Anaconda. Discussed by George A. Packard, W. B. Daly, B. B. Gottsberger 25 Norris, E. M. and Rahilly, H. J.-Mine Fires. Discussed by R. Dawson Hall, W. B. Daly, Frank Haas, D. Harrington, Robert E. Tally 26 Raymond, R. M.-Safety Practice for Hoisting Ropes. Discussed by B. F. Tillson, Graham Bright, Rudolph Kudlich, J. F. Howe, Robert Peele, H. G. Davis. 30 Howe, J. F.-Use of Wire Rope in Mining Operations. Discussed by Horace F. Lunt, J. F. Howe, B. F. Tillson 36 Tanner, W. N., and Jaccard, F. C.-Wire Rope and Safety in Hoisting at Butte Mines. Discussed by Horace F. Lunt, W. B. Daly, C. L. Colburn, William Kelly, Robert Peele, B. F. Tillson, Graham Bright, Charles E. Locke 38 Richardson, A. S.-Ventilation of Butte Mines of Anaconda Copper Mining Co. Discussed by D. Harrington, Chas. A. Mitke 42 Stuart, Charles E.-Storage-battery Locomotive as Applied to Mine Haulage. Discussed by Howard N. Eavenson, Charles E. Stuart, William Kelly, Arthur Thacher, W. H. Patton, Graham Bright 45 Woodward, C. D.-Electric Haulage Systems in Butte Mines. Discussed by William Kelly, Graham Bright, Howard N. Eavenson, C. E. Arnold, Gerard B. Rosenblatt, K. A. Pauly 47 Harrington, D.-Efficient Ventilation of Metal Mines. Discussed by R. E. Simpson 52 Otagawa, Masayuki.-Mining Methods at the Ashio Copper Mine. Discussed by Horace V. Winchell, D. W. Brunton 52 Stoek, H. H. and Clagett, Thomas H.-Coal Mining Methods. Discussed by P. D. Browning, G. L. Cox, Erskine Ramsay, Frank Haas, George S. Rice.

Jan 6, 1922

THE CHAIRMAN (F. K. COPELAND,* Chicago, Ill.).-At this particular time conditions existing in this, country, and elsewhere, make all questions of milling or smelting or mining, or anything else, absolutely secondary to the one question of labor. We have always devoted our attention largely to the efficiency of machinery, and to reductions in costs, etc., and have let this tremendous problem of our relation to labor more or less take its own chances. There has never been a time when those who are responsible for the operation of business of different kinds were as com-pletely at a loss as they are now, so that anything that can be brought out that relates to labor is, to my mind, of utmost importance. T. T. READ, Washington, D. C.-This formulation of a method of curtailing forces at the Copper Queen is a notable step in advance of our treatment of personnel in the mining industry. So far as I know, it is the

Jan 12, 1919

By T. L. Joseph

The extent to which hot metal from the blast furnace affects open-hearth practice and the quality of steel produced has been discussed widely. Open-hearth operators have attributed difficulties experienced in making satisfactory steel to characteristics of the pig iron not disclosed by ordinary analysis. The commonest criticism of the iron has been that it is "physically cold" or "dirty." Often when the blast furnaces are working irregularly the quality of the iron is questioned. A cold hearth, slipping and hanging, the use in the past of unsintered flue dust, and the use of ores difficult to smelt have been associated with the production of iron of poor quality. The difficulty of the situation is that we have no proven yardstick for quality aside from ordinary analysis. Uniformity in analysis is recognized as being important, but the difficulty of changing the open-hearth practice when the iron analysis varies widely may not always be fully appreciated. Although the problem of correlating the characteristics of steel with those of pig iron is admittedly obscure, the effort of producers of quality steel to investigate all factors that may have a bearing on the final product is justified. This report contains data on the oxides in several hundred casts of basic iron produced in a furnace during the course of normal operation on Lake ores. Incidental to the study of the oxides in the iron, it was desirable to follow closely the temperature of the iron. The effect of temperature of the iron upon the silicon and sulphur present is discussed. A general relation between the basicity of the slag and the sulphur in the metal was developed. The amount and composition of oxides in the hot metal and in the steel bath during various intervals between melt-down and tap are discussed. Heats of rimmed steel, killed steel, and semikilled steel were investigated. The hot metal on individual heats was either all taken from a mixer or consisted partly of direct metal and partly of metal from the mixer. Samples of the iron for oxide determinations were

Jan 1, 1937

By L. L. Oriard

In order to predict the influence of blasting on slopes, one must first understand the action of explosives, the manner in which rock is broken or displaced, and how seismic waves are transmitted, and the nature of these seismic waves. In this paper, the author describes the action of high explosives on rock masses, beginning at the source of the explosion, extending through the zone of rupture to a distance where only elastic waves of low energy persist. The paper describes the relationships between explosives charge quantities and distances, including the character and intensity of the seismic waves in various types of terrain. In looking at the analysis of slopes subjected to seismic waves, it has been common practice to assume a simplified model in which the anticipated acceleration is applied horizontally to the slope as an equivalent static force, or a model in which there is a rigid base subjected to mechanical shaking. Such models do not accurately portray blasting activity taking place within or near the slope in question. In dealing with blasting effects, it is important to under- stand seismic wave types, wave lengths, attenuation and transmission paths, as well as vibration intensity. In most cases, those slopes that are the least stable under static loading will also be the least stable under dynamic loading, although there may be rare exceptions. Thus, the more that is known about a slope statically, the better will be the assessment of it dynamically.

Jan 1, 1983

By Robert M. Grogan

Fluorspar is the commercial name for fluorite, which is the mineral having the composition CaF2, calcium fluoride. Its valuable properties are due to its content of fluorine, and it is the only important commercial source of that element. The name is derived from the Latin fluere, to flow, because the mineral melts easily and is a good flux. History The mineral has been known since Greek and Roman times, when it was used for drinking cups and ornamental slabs. Various peoples including the Chinese and the American Indians have carved ornaments from large crystals. Its usefulness as a flux was known to Agricola, who wrote about it in 1546.1 Mining began in England about 1775 15 and at various places in the United States during the period 1820 to 1840.28 Substantial production was achieved first in the period 1888 to 1900 in consequence of the development and widespread adoption of the basic open hearth method of making steel, in which fluorspar is used as a flux. After that, production and usage was stimulated by growth in the steel, aluminum, chemical, and ceramic industries and accelerated by World Wars I and II. The organic fluorides called "Freons" entered the picture in 1931, and the use of anhydrous HF as a catalyst in the manufacture of alkylate for high octane fuel blends began in 1942. The development of the froth flotation process in the late 1920's, a differential flotation scheme for separating fluorspar from galena, sphalerite, and other minerals in the 1930's, and the application of heavy-media concentrating methods to the treatment of low-grade ores in the 1940's were outstanding technological contributions that enabled increased production of fluorspar concentrates. Composition and Properties Fluorite in its purest form contains 51.1 pct calcium and 48.9 pct fluorine. Substitution of small percentages of cerium and yttrium for calcium have been noted.4 Mechanical inclusions of gases and fluids such as petroleum and water, and of other solid minerals such as pyrite, marcasite, and chalcopyrite are common. The fluorspar of commerce contains attached and admixed mineral impurities, chiefly calcite, quartz, barite, celestite, and various sulfides. It is interesting that the purest commercial form in which the mineral is sold, acid grade concentrate, contains a minimum of 97 pct CaF2, and as such is of comparable purity to many reagents used in chemical laboratories. Fluorite has a marked tendency to occur in large, well-formed crystals sometimes six to ten inches on a side. It crystallizes in the isometric system, frequently forming cubic and octahedral crystals or combinations thereof. The mineral also occurs in massive and in earthy forms, and in crusts or globular aggregates with radial fibrous texture. Crystalline fluorspar exhibits a great array of colors, from colorless and water clear to yellow, blue, purple, green, rose, red, bluish and purplish black, and brown. The colors are often arranged in alternating bands parallel to cube faces. They may be altered by exposure to X-rays, heat, ultraviolet light, and pressure, and are caused by a variety of factors including the presence of trace impurities and displaced ions in the lattice. Sometimes the changes induced by X-rays can be reversed by ultraviolet radiation. The mineral has a hardness of 4, and is the model of that hardness on the Mobs scale.

Jan 1, 1960

By Brehon B. Somervell

SOMEONE has called this war a war of gadgets. Someone else says it is an engineers' war. It is a war of production, transportation; a war in the sky; a war on wheels; a civilians' war. Let us not quarrel about nomenclature. Call it what you want. If four motored bombers and thirty-ton tanks are gadgets, then it is a gadget war. Engineers, scientists, shop laborers, air-raid wardens all have their highly important jobs to do. The fact remains that this war, like all others, is a soldiers' war. The basic strategy employed today is the same strategy that Philip of Macedon used on the Plains of Thessaly twenty centuries ago. His phalanx was a striking force armed with every known weapon. It was armored with breastplate and casque. It depended for success on superior man power and mobility, upon superior weapons and supply, and upon superior discipline. It executed commands faster than its enemies; it had more catapults and spears, more men in the back areas bringing up supplies. It was a new idea. It used what today we call the scissors movement to cut up its foes. It took sharp advantage of surprise. It introduced terror as a weapon-terror inspired by a vast, moving, shouting army with banners. It laid waste the cities by fire. The Greeks had a word for it but that word wasn't "blitzkrieg."

Jan 1, 1942

By Dozier Fircley

SOME nonmetallic minerals and their products, such as portland cement, common brick and hollow tile, sand, gravel, crushed rock, vitrified salt-glaze clay pipe, and the like, are a necessity in every community. They are mineral in nature but the establishment of plants for their production is usually a local and elementary problem. Yet it is probable that an economic study of the problem in every locality will show that such nonmetallic mineral commodities are not always obtained in the most economical way, or in the best quality. Other nonmetallic minerals are of such value that they may be shipped for long distances and sold in sufficient quantities to establish prosperous commercial ventures. Among these are phosphates, barium compounds, borates, nitrogen compounds, magnesium compounds, sulfur, asbestos, and potash. Success in marketing such products depends on quality, production cost, transportation, and similar conditions.

Jan 1, 1932

By D. B. Hobbs, L. W. Kempf, R. S. Archer

SILICON is one of the most important elements in the metallurgy of aluminum. It is always present in small amounts in the ordinary grades of "pure" aluminum, and hence in all alloys made therefrom. Within the last few years binary alloys containing up to 13 per cent. of silicon have come into extensive use for castings. Silicon is also added, beyond the amount present as an impurity, in alloys containing one or more other elements such as copper, manganese, magnesium and nickel. The binary aluminum-silicon alloys are not yet heat treated to any extent in commercial practice, although, as will be shown, their properties are affected to a very considerable degree by heat treatment. There are other aluminum alloys that develop higher strength, but the special characteristics of the silicon alloys may well lead to the application of heat-treating processes on a commercial scale. The role of silicon in the heat treatment of aluminum alloys is more important than would be indicated by consideration of the binary alloys alone, because many of the alloys that are heat treated in regular commercial practice contain some silicon in addition to that derived from the aluminum ingot as an impurity. Among these may be mentioned the heat-treated 195 alloy castings, and the wrought alloys 25S, Special 17S and 51S of the Aluminum Co. of America, and the German wrought alloy, Lautal. It is the purpose of this paper to present the results of experimental work and the conclusions derived therefrom regarding the heat treatment of the binary aluminum-silicon alloys. The products heat treated included forgings, chill castings and both "normal" and "modified" sand castings. REVIEW OF LITERATURE The literature on the heat treatment of aluminum-silicon alloys is not very extensive. The following review gives the principal references of which the authors are aware, in which appreciable information may be found.

Jan 1, 1928

By J. A. Singmaster

A REPORT that it did not pay to use present-day galvanized iron on account of the short life of the material, accompanied by proofs of the state-ment in the form of a tabulated history of the first costs of various kinds of building materials and their main-tenance expense, started an investigation of modern galvanized products. At the very outset it was apparent that our experience with galvanized products was by no means unique. Correspondence with the State Agricultural Depart-ments, the Agricultural Experiment Stations, the County Agents and State Granges all over the United States brought a mass of complaint on this same score. Visits to large buyers of galvanized sheet and wire revealed the same condition coupled with an ever-increasing use of substitutes for galvanized iron. We believe, therefore, that the title of this article is fully warranted by the experience of the consuming public. A study of the proceedings of the various societies having to do with the testing and use of sheet iron and steel products revealed a tremendous amount of work on the life of the base metal itself. Great stress was laid on differences in life of various types of iron and steel, the difference amounting at best to months rather than years. Very little recent attention has been paid to a study of the life of the zinc coating and the causes of its present-day lack of durability. There have been some real exposure studies published, how-ever, which show that the weight of the zinc coating determines the protection afforded by the galvanizing, which is of far greater influence on the life than the base-metal composition. An interesting paper was published by the Phillipine Journal of Science in 1916, entitled: "Galvanized Roofing in the Phillipines," a contribution from the Bureau of Science of the Phillipine Island Government. The author, Mr. Arguelles, found on 18 old galvanized sheets, after from 30 to 35 years' exposure, from 2.3 to 4.1 oz. of zinc per sq. ft. of sheet and sums up the study by saying: Of the various factors influencing the durability of galvanized iron which have been studied with a view towards accounting for the difference in behavior of old and modern sheet, it appears evident that the greater weight of zinc per unit of area on the former accounts for the greater durability.

Jan 10, 1922

By A. Hultgren

PAGE Outline of Progress of Knowledge and Theories about Gas Evolution in Steel Ingots, and Its Influence on Crystallization and Segregation 2 Object of Present Investigation 16 theoretical Discussion of Process of Solidification 17 Gas Given Off from Rimming Steel during Solidification 17 Equilibrium Diagram of the Iron-carbon-oxygen Alloys 19 Solidification of Pure Iron-carbon-oxygen Alloys 25 Solidification When Carbon Monoxide Is Given Off at Constant Pressure... 25 Solidification When Gas Evolution Is Suppressed 26 Schematic Application on Solidification of Rimming-steel Ingots 27 Influence of Manganese, Sulphur and Phosphorus 28 Experimental Work 30 Liquid Steel and the Mold Gas 30 Ingots Investigated and Methods Used 33 Ingot Structure 42 Structure of Rim Zone 42 Structure of Core 49 Structures Obtained under Special Conditions of Freezing 50 Distribution of Metalloids 55 Other Observations Made 60 General Discussion of Solidification Process 63 Condition of Liquid Steel before Casting 63 Rimming Period 70 Composition of Rim Zone 93 Freezing after Top Is Closed 96 Slag Inclusions and Ingot Scum 102 Reaction between Gas in Blowholes and Surrounding Solid Steel during Cooling 103 Summary 105 Appendix-Preparation and Etching of Ingot Sections 106 References 107 IN 1934, Jernkontoret (The Swedish Ironmasters' Association) appointed a committee for the study of the structure of rimming-steel ingots and the various phenomena associated with their solidification. The members of the committee, including those who have joined it later, have been: I. Bohm, B. D. Enlund, B. Kalling, M. Tigerschiöld, 1. Wohlfahrt and the authors. The present paper? is a somewhat

Jan 1, 1939

By AIME AIME

ADDRESSING the Ohio Section at a recent meeting in Columbus, Ohio, R. C. Allen, executive vice-president for Oglebay, Norton & Co., Cleveland, spoke on "The Iron-Ore Industry of the Lake Superior Region in Prosperity and Depression." The speaker considered this region in connection with the problem of national security. This is the age of minerals; progress depends on them; and next to agriculture, the mineral industry is of prime importance. The United States has no shortage of minerals rather an over-supply; but many mines have been and are being exhausted. The shifting of the sources of supplies of minerals so important as copper, petroleum, and iron to other countries would create internal strains and affect international relations. There will be no early decline of ore mining in the Lake Superior region unless it is forced by unwise public policies. Iron ore is industrial strength and self-sufficiency. A study of economic geography is important for statesmen and mining men, because the minerals essential for peace and war are haphazardly or irregularly distributed throughout the world. Of these minerals, 75 per cent are owned by 10 per cent of the population, mainly peoples of Anglo-Saxon origin.

Jan 1, 1934

By George Mixter

MINING, in contrast to manufacturing, deals with a wasting asset. That which is taken out of the ground is gone, the property is depleted to that extent, and will eventually become exhausted of profitable ore. So the life of a mining company is dependent upon the ability of its management to develop improved methods to permit extraction at a profit of the lower-grade ores which remain, to extend by intelligent exploration the limits of its known ore bodies, and to find and acquire new properties to take the place of those that, for one reason or another, are no longer operated. Its history is a story of constant change, of the working out of properties here and the acquisition and development of properties there, to maintain the vitality of the whole. It is a story of estimating with the tools and the knowledge available the location and extent of hidden ore bodies and of devising the means of extracting

Jan 1, 1948

By H. O. Hofman

WITH the exception of lead sulphate, all common metallic sulphates are completely decomposed upon heating into metallic oxide, sulphur trioxide, sulphur dioxide and oxygen. Some give up their trioxide readily at a low temperature, others require considerable heat and much time to be completely freed from sulphur. Kerl in 1881 arranged the principal metallic sulphates as they are decomposed by a rising temperature in the following order: silver, iron, copper, zinc, nickel, cobalt, manganese and lead, lead sulphate being decomposed only slightly at a white heat. The researches of Bradford, published in 1903, show, however, that ferrous sulphate is decom¬posed at 590° C., cupric sulphate at G53° C. and argentic sulphate at 1,095° C. By the present investigation it will be seen that zinc sulphate is decomposed at 739° C. As far then as our present knowledge goes, the order in which the decomposition of the leading metallic sulphates takes place is the one given in Table I.

Jan 1, 1905

G. A. Moore—The tin-fusion method has been a very favorable possibility for many years. The authors apparently have settled the question that delayed the method for a long time by showing that no hydrogen is absorbed in the tin. This, of course, is very important. I want to make a few remarks concerning the absolute accuracy of analysis, which must be the final basis for deciding among the various methods. From the figures in the paper, there seems to be some re-maining slight discrepancy on the actual amount of hydrogen present in various samples which may be presumed essentially identical. (This is of the order of the precision of individual analyses but appears in averaged results.) From the analyst's viewpoint, the tally of hydrogen content can be regarded as occurring in three portions. First is a large portion which comes off easily and automatically during sample storage and later on heating in the apparatus. This is fairly easily analyzed. Second is an item which may be either positive or negative in the tally sheet. In warm or hot evolution, this is a portion which, in practice, can never be re-

Jan 1, 1951