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IDO not want to omit anything in which fire or its operation has a part, if I know or can tell it, and have already told you so many other useful, powerful, and ingenious effects (finally of powder and other' fire deadly and very injurious to all living things, indeed, composed for the destruction of those who possess it as well as those who do not) but I do not want the end of my writing to be in tragedy. Therefore I wished to tell you how, from these fires composed of forceful and horrible mate¬rials bringing harm and terror to men, a happy and pleasing effect is also produced and, instead of fleeing from it, the people willingly go to see it. Among others I remember that it was once customary to use these in Florence and in Siena, more than elsewhere. The chief feast day celebrated. by one of these cities is the day of the birth of Saint John, and the other is the Assumption of Our Lady, on the fifteenth of the month of August. In the morning they visit the shrines with great devotion and solemnity, displaying their pomp as much as possible, and later they hunt lions, wild bulls, untamed horses, and many other animals. In the same public squares there was also erected as a decoration an edifice fixed in the ground in the middle of this space, or hanging from a heavy rope crossing between the loftiest points of equal height that could be found in that place. This they have done and still do, and perhaps in time to come will continue to do when opportune. This structure was usually of wood; indeed it is necessary that the latticework of its construction be made only of this. It was covered and en¬larged by tying and fastening hay on top to bring it almost to completion and then papier-mâché was applied. [165v] The figures were first appropriately painted and made of a combination of vessels one above the other, developing various decorative figures in relief which should represent some fable or history and should not appear haphazardly made or without understanding. Now the master proceeded to arrange these figures in a composition according to his skill or art of design, and likewise planned

Jan 1, 1942

By Sidney H. Haughton

WHEN the white pioneers of the eighteenth and nineteenth centuries advanced from the coastal settlements of southern Africa into the interior of the subcontinent, they found it inhabited, more or less sparsely, by brown or black peoples mainly of pastoral habits but equipped with a fighting spirit and certain fighting weapons. Some of the tribes were smiths, others were miners and metallurgists; all used fuel, either industrially or domestically. Some of that fuel was wood, some cattle dung, and in some places the natives mined outcrop coal. Coal was first discovered by Europeans in Natal about 1840. After proper deliberation and after allowing due time for a consideration of all the implications, the Natal Government decided in 1881 (40 years after) to import an English expert to investigate and report on the discovery. Things then moved rapidly, and in what to a geologist is the remarkably short space of eight years, Natal collieries were producing at the rate of nearly 30,000 long tons per annum or 100 long tons per working day!

Jan 1, 1945

SOME days ago a visiting member from Pittsburgh who is an ardent supporter of the Institute remarked: "There are a lot of men who would be members of the Institute if it weren't so expensive. It is not so much the $15 dues as the $20 initiation fee. This makes quite a hurdle, especially for the younger fellows." A little further conversation developed the fact that the member had never learned of the changes in the By-laws regarding initiation fees and dues made by unanimous vote of the Board of Directors last November. As a great many others doubtless are unaware of these changes, the substance of two of the amendments is here repeated. They provide: (1) That the initiation fee for Junior Members (heretofore ten dollars) he abolished. (2) That the age limit for entrance as a Junior Member be increased from 27 years to 33; provided further, that the period during which the dues of a Junior Member are ten dollars shall be a maximum of six years but in no event shall extend beyond his thirty-third birthday. The Junior Member gets the identical privileges enjoyed by his seniors and he likewise assumes the same obligations with the sole exception of the financial payments. This one exception is justified by the fact that the engineers of more mature years, who are established in the profession, - are able and willing to assume a slightly greater financial burden. In effect, it is a small subsidy for the younger men; but these in turn will later enter the group of those that give instead of receive assistance. The practical result is that an engineer under 27 can obtain every privilege and benefit of membership for six years on the payment of only $10 per year without any initiation fee. A man of thirty can do the same for a period of three years. Incidentally, a candidate applying for membership (either as senior or junior) in the next few months need pay dues for the second half of 1935 only. A Junior Member -can be enrolled with an immediate outlay of only $5. The Institute does not seek-members indiscriminately merely to swell the number. These facts are not presented as a "bargain" offer in any sense. The standards for admission are high and are watched zealously. But it frankly-wants to give qualified men who can benefit from membership every encouragement to apply. Naturally, the Institute does not want lack of accurate information regarding initiation fees and -dues to be a stumbling block to any that are eligible and desirous of enrolling. Members are urged to take it upon themselves to clear up misapprehensions on this point, particularly among younger engineers.-Editorial reprinted from MINING AND METALLURGY, May, 1935.

Jan 1, 1935

By M. F. Trice

PYROPHYLLITE is a hydrous aluminum silicate (A12Si4010(OH)2)1 that occurs in both the foliated and the massive forms. The foliated variety resembles talc in that it has a greasy feel, a pearly luster, perfect basal cleavage, and usually is white, although in some deposits apple green, gray, brown, russet, and nearly black specimens may be found. The massive deposits of pyrophyllite yield pearl gray to light tan aggregates, some of which are so friable that they may be crushed with the hands into a fine gritty powder. Frequently specimens of the massive variety are studded with crystals of radial structure. The mineral has a specific gravity of about 2.7 and a hardness of 1 on Mobs' scale.1 The chemical composition of commercial pyrophyllite reflects the mineralogy of the deposits, which, according to Stuckey,2 contain pyro-phyllite and quartz, together with chloritoid, sericite, and a few other minerals of negligible importance. The latter, he says, "are noticed in but small quantities to the extent they might occur as accessory constitu-ents of an igneous rock or as products of regional metamorphism or weathering. . . . Quartz is abundant everywhere except in the very best grades of pyrophyllite." Analyses of specimens from several deposits are listed in Table 1, showing that the silica content varies from 57 to 73 percent and the alumina from 22 to 33 percent. Oxides of iron and the alkaline metals are collectively present, with one exception, to an extent of about 1 to 1.5 per cent.

Jan 1, 1940

By F. J. Cuddeback

For low-head pumping of small quantities of water, the water jet, or hydraulic educter, has been used to advantage by Eagle-Picher Mining and Smelting Co. in the Tri-State district. Water-jet pumps are used for draining sumps and pockets up to 15 ft. in depth. They have been used very successfully when only moderate amounts of water are encountered in taking up bottom. A small, easily handled unit is desirable in this work, especially while opening and deepening a new stope. Small air pumps are convenient but can be used only on the day shift, when air is available. Obviously, a jet pump of smaller capacity but operating 24 hr. prevents lost time at the start of each shift. No tests have been made on their power efficiency, but admittedly it is low. However, for certain kinds of work this is offset by their handiness, low initial cost, low upkeep, and reliability. They will handle slime and sand without ill effect, and will continue to pump indefinitely on air. This foolproof 24-hr. performance has led to their continued use at some places even after electric pumps with better power efficiency could have been installed. The success of jet pumps depends largely upon a cheap source of high-pressure water. Owing to mine depths in the Tri-State district, pump pressures range from 100 to 150 Ib. per sq. in. In many mines it is common practice to handle the normal inflow water with triplex pumps ranging in size from 3 to 8 in. The pumps operate 24 hr. per day, and, in order to handle emergency conditions, are speeded slightly faster than necessary to pump the normal inflow. The sump level is governed by controlling the by-pass water with a butterfly valve and float. This method is somewhat wasteful of power, but permits the pumps to operate with a minimum of attention. Such an installation is visited once a day to check lubrication. Hence, if some of this water, normally by-passed to the main sump, were used to operate a jet pump, the power cost could be considered low regardless of efficiency. Figs. I and 2 show two water jets that have done satisfactory work. The one in Fig. 2, made up entirely of pipe fittings, may be of interest partially because of its novelty, but does better work than its appearance indicates. The pipe fittings for this jet as shown cost $2.20. Some improvement in its design may be made by cutting out the 135 by 1¼-in. reducer to a smoother taper as shown by dotted lines. A 3-in. suction pipe is sometimes used in order that the discharge may be as straight as possible. A 2-in. discharge line has been used frequently, but 3-in. pipe is used where several hundred feet of discharge is required.

Jan 1, 1946

By F. M. Lewis, J. F. Myers

The paper reports the development of a large, slow speed ball mill closed circuited with a hvdro-scillator. This increased grinding efficiency 28 pct over conventional units. AS the title indicates, this is a progress report for the first year of experimental operation of a relatively large diameter, slow speed ball mill with 1-in. balls, with and without various classifiers, and including a hydroscillator. Several years ago the authors came to the conclusion that if any further progress were to be made in our flotation process, an understanding of the chemical and physical reactions and the control thereof, in the grinding circuit, was essential. It may be stated, at this point, that the preparation of a correct feed for the flotation process is still the number one objective of our grinding studies. This progress report deals with grinding "per se," and not with the chemical and physical reactions as the result of grinding. Prior to this time we had taken the naive position, that since grinding had been practiced by the industry for some fifty years or more, it had been well exploited and developed by a host of investigators. Consequently, we had given the matter only superficial attention. At the start of our study, we were aware of the fact that some difference in opinion existed, but we were not prepared for the controversial evidence that developed nor for the extent to which the experts differed in their viewpoints. There seemed nothing else to do but to tour the continent and decide for ourselves what was right and what was wrong, read all the published literature and visit with anyone who had ideas about the matter. This we did over the next few ensuing years. Since our study has met with some measure of success, we report, herewith, these data that ultimately they may be of help to other investigators. In 1944 it became necessary to increase our grinding capacity and at the same time to grind the sulphide portion a little finer. This provided the impetus to put our ideas into effect. As has been previously described, our grinding flowsheet at that time consisted of a 6x12 rod mill, followed by two 5x10 ft, and one 6x12 ft trunnion overflow ball mills, with conventional rake classifiers. Naturally, we first considered all the possibilities of altering or adding to the existing equipment. It became evident that if any appreciable increase in grinding efficiency could be obtained, it would pay to scrap the existing small mills and classifiers and install one big mill with adequate classification. Trying to determine just how much more efficient a big mill could be, in which were incorporated all

Jan 1, 1951

By J. F. Myers, F. M. Lewis

The paper reports the development of a large, slow speed ball mill closed circuited with a hvdro-scillator. This increased grinding efficiency 28 pct over conventional units. AS the title indicates, this is a progress report for the first year of experimental operation of a relatively large diameter, slow speed ball mill with 1-in. balls, with and without various classifiers, and including a hydroscillator. Several years ago the authors came to the conclusion that if any further progress were to be made in our flotation process, an understanding of the chemical and physical reactions and the control thereof, in the grinding circuit, was essential. It may be stated, at this point, that the preparation of a correct feed for the flotation process is still the number one objective of our grinding studies. This progress report deals with grinding "per se," and not with the chemical and physical reactions as the result of grinding. Prior to this time we had taken the naive position, that since grinding had been practiced by the industry for some fifty years or more, it had been well exploited and developed by a host of investigators. Consequently, we had given the matter only superficial attention. At the start of our study, we were aware of the fact that some difference in opinion existed, but we were not prepared for the controversial evidence that developed nor for the extent to which the experts differed in their viewpoints. There seemed nothing else to do but to tour the continent and decide for ourselves what was right and what was wrong, read all the published literature and visit with anyone who had ideas about the matter. This we did over the next few ensuing years. Since our study has met with some measure of success, we report, herewith, these data that ultimately they may be of help to other investigators. In 1944 it became necessary to increase our grinding capacity and at the same time to grind the sulphide portion a little finer. This provided the impetus to put our ideas into effect. As has been previously described, our grinding flowsheet at that time consisted of a 6x12 rod mill, followed by two 5x10 ft, and one 6x12 ft trunnion overflow ball mills, with conventional rake classifiers. Naturally, we first considered all the possibilities of altering or adding to the existing equipment. It became evident that if any appreciable increase in grinding efficiency could be obtained, it would pay to scrap the existing small mills and classifiers and install one big mill with adequate classification. Trying to determine just how much more efficient a big mill could be, in which were incorporated all

Jan 1, 1951

By Claude P. Heiner

While the title of this paper embraces the entire West Coast, the author, in the interest of simplification. has confined the discussion to California-particularly the central section. California's population has, risen 45 pct since 1940. Its electric requirements have also increased, not only because of the growth in industry and population but also because of the widespread tendency of all types of electric consumers to use more electricity than ever before. The growth of California's electric utilities is shown by published data covering operations, of three of its large systems and is given in Table 1.

Jan 1, 1949

By Arthur R. Still, Paul Gilmour

The ore deposit of the Iron King mine occurs in a group of steeply-dipping metamorphosed eugeosynclinal volcanic and sedimentary rocks of Precambrian age. Within this sequence, the ore deposit lies at the contact of a unit made up of rhyolitic tuff and interbedded andesite and a structurally underlying series consisting of andesitic tuffs, minor rhyolitic tuffs, and argillaceous sediments. Field evidence suggests that these rocks have been overturned. The ore deposit is made up of a series of overlapping, conformable or bodies consisting of massive pyrite and associated lenses of massive quartz. These contain recoverable amounts of gold, silver, lead, zinc, and copper. A parallel zone of copper mineralization occurs within the hanging-wall rocks. The deposit is considered to belong to a large and important group characterized by mineralogical composition and the lithology and structural type of the host rocks. Evidence regarding the origin of the deposit is reviewed, and it is concluded that the ore bodies were formed through the agency of volcanic hot springs on, or near, a submarine surface of deposition

Jan 1, 1968

By W. C. Lacy

This article is a progress report of a program designed to quantitatively evaluate geological parameters to predict stable slope angles. The author feels that, although there does not appear to be any one technique or characteristics that will suffice as an index to the determination of stable slope angles, a combination of seismic methods as outlined here, detailed geological mapping and logging of core, and a better understanding of the angle of internal friction in rock types will permit accurate estimation. A mining engineer friend once remarked, "If we don't have pit slope failures, the slopes are too flat." Since economic justification of an open pit project is based upon ultimate pit slopes, we cannot wait until the pit is developed and slopes established by trial and error. Some combination of geological and/or geophysical techniques must be developed to permit accurate prediction of stable slope angles and to suggest modification of pit outlines to result in slopes enabling maximum economic yield. This presentation is a progress report of a program designed to quantitatively evaluate geological parameters to predict stable slope angles. The principle of the weakest link applies to any slope stability evaluation and necessitates detailed geological examination and recording of observations. Physical failure will occur along any surface where shearing stress exceeds shearing resistance. Rock conditions are seldom uniform even within a single cut or pit face, so stability conditions will vary. Consequently, both plan outline and ultimate slope limits must be tailored to the specific situation. Economic advantages to be gained by slight increases in slope angles in deep pits are well recognized and stimulate efforts to obtain maximum permissible slope angles. MECHANICS OF SLOPE FAILURE Excellent reviews on the nature of slope failure have been presented+2,6,8,11 For the purpose of this study, the writer considers failure to take place by one or more of three processes: 1) ravelling, 2) translation or slope failure, and 3) rotation or base failure (Fig. 1). The effects of increased pore water pressure in soils were recognized in 1923 by Terzaghi in his development of the concept of effective stress, and he has applied the same principle to jointed rocks designating water pressure as cleft-water pressure.8 Cleft-water pressure in a rock slope reduces normal pressure on the plane of failure, thus reducing shearing resistance and resulting in slope failure. In the following discussion it is assumed that adequate drainage is supplied to prevent any build-up of water pressure. This is the first step in any program to establish maximum slopes. Ravelling: Ravelling occurs in rocks with low cohesion and entails the free movement of individual fragments ranging from single rock falls to running ground. Removal of lateral support wherever slope angle exceeds the angle of repose of the rock parti-

Jan 1, 1963

THE Institute of Metals Division of the A. I. M. E. has joined with the American Society for Steel Treating and the American Welding Society in support of National Metal Week in Philadelphia, Oct. 8 to 12. Individual and joint technical sessions, plant inspection trips, and a general exposition to be held in Commercial Museum have all been arranged. With the coming of the Institute of Metals Division into the circle, the scope of the exposition has been broadened to cover non-ferrous metals, and exhibits of much interest are promised. Headquarters for the Institute of Metals and the American Society for Steel Treating will be at the Benjamin Franklin Hotel, and for the American Welding Society at the Bellevue-Stratford. The American Society for Steel Treating and the Welding Society will hold technical sessions each forenoon at their hotel headquarters. The Institute of Metals Division will hold sessions Tuesday morning and Wednesday and Thursday afternoons; that for Wednesday being a joint session with the American Society for Steel Treating. The latter society will hold independent afternoon sessions on Thursday and Friday. Registration and information desks will be open at the hotels throughout the week, and an attractive program of entertainments has been arranged.

Jan 1, 1928

By Warren Smith

IT has been 5 years since the writer left the Philippine Islands and while in that country his chief work did not lie in this field, though he has visited all but one of the localities mentioned in this article. The principal field studies relating to oil were made by his colleague, Mr. Wallace E. Pratt. The writer's investigations dealt with the general stratigraphy and paleontology of the Philippines. With the exception of the investigations made by Mr. Pratt and the writer very little information on this subject is available. A number of geologists in the employ of large oil companies have visited the Islands from time to time but, following the general rule, the public has scarcely ever been permitted to learn anything of the results. The writer is indebted to the Bureau of Insular Affairs, Washington, for late information regarding recent legislation in the Islands relating to petroleum. All the known oil seeps, petroleum residues, such as ozocerite, and natural-gas emanations are associated with Tertiary sediments. The chief seeps and most promising prospects are located as follows: 1. Bondoc Peninsula (lower end), Tayabas Province, Southeast Luzon. 2. The west coast of the island of Cebú from Alegria north to, and perhaps beyond, Toledo. 3. Central Mindanao not far from Lake Lanao. 4. The ozocerite veins on the Island of Leyte in the northwestern part in the vicinity of the town of Villaba. 5. Natural gas from some deep wells in Tertiary shale formations on the eastern flank of the Cordillera and extending out under the plain on the island of Panay.

Jan 2, 1920

By C. C. Harris, A. Jowett, S. K. Ghosh

An equation derived from first-order kinetics and accounting for return from froth to pulp has correlated continuous flotation data. The concentration of floatable material in the pulp can be altered either by changing the feed concentration or the feed rate. The latter does not affect the flotation rate constant, the froth to pulp return constant, and the concentration of non-floatable material in both the pulp and concentrate. Both the return constant and the concentration of non-floatable material in the pulp are directly proportional to the feed concentration, while the concentration of non-floatable material in the concentrate is related to the feed concentration. The investigation of the froth flotation process by continuous test methods, previously used by Brown and smith,1 Jowett and Safvi2 and Jowett and West,3 is being continued. Recent tests, primarily concerned with flotation cell design, have yielded kinetic data suitable for testing an equation proposed by Arbiter and Harris4 which postulates that a flotation process is defined by two rate constants: 1) the rate constant for mass transfer from pulp to froth. Previous workers have regarded this as the flotation rate constant. 2) the rate constant for mass transfer from froth to pulp, which has previously been ignored. THEORY Under continuous flow conditions at the steady state in Fig. 1 the equation developed4 is Symbols are defined in Table I. The air-liquid ratio terms4 have been omitted, since they are substantially constant for a given set of conditions. Also, for a system operating at the steady state Vf and V, remain constant and Eq. 1 can be written: Cp/Cc=b'/a,+Qc/a' [2]

Jan 1, 1963

By R. R. Joseph, K. A. Gschneidner

The solid solubility of magnesium in the close-packed modifications of lanthanum, cerium, praseodymium, neodymium, gadolinium, dysprosium, and lutetium was determined from approximately 250°C to the eutectoid temperature by the X-ray parametric technique. The maximum solubility at the eutectoid temperature was found to be 9.4 at. pet in La, 8.2 in Ce, 9.2 in Pr, 8.2 in Nd, 14.1 in Gd, 13.5 in Dy, and 11.5 in Lu. The solubility when compared at a homologous temperature was found to increase in a smooth manner with decreasing size factor from lanthanum to lutetium. It was found that the apparent atomic radius of magnesium when dissolved in the lanthanide solvent was constant and could be accounted for by consideration of several models dealing with departures from Vegard's law. The eutectoid temperatures for the lanthanide-rich La-Mg, Ce-Mg, and Nd-Mg systems were found to be 544", 505°, and 551°c, respectively. A study of the solid solubility of magnesium in the lanthanide metals was initiated because the valency and electron egativity difference are essentially constant and favorable for solid-solution formation, and thus one could examine the effect of size on terminal solid solutions. The size factors based on metal radii range from 14.6 pet for lanthanum to 7.5 pet for lutetium. Since the electronegativity difference is small, 0.06 unit or less, application of the Hume-~othery' and Darken and Gurry2 criteria for solid-solution formation indicates that the solubility of magnesium would be expected to be small for lanthanum (between 5 and 10 at. pet) and to increase as we proceed along the lanthanide series. A search of the literature revealed no data on the solubility of magnesium in the lanthanide metals except for the solubility of magnesium in cerium at 450oCA typical phase diagram for the lanthanide-rich end of the lanthanide-magnesium phase diagram is shown in Fig. 1. EXPERIMENTAL PROCEDURES Preparation of Alloys. The lanthanide metals used in the preparation of alloys for this investigation were prepared from the corresponding fluoride by metallothermic reduction techniques previously described by Daane.4 The chemical analyses of the metals used are listed in Table I.

Jan 1, 1965

By H. B. FERNALD

THE interesting and carefully developed formula which Professor Bucky presents for answering the question of whether proposed new equipment will give a net return on investment equal to or greater than that on present equipment starts with an assumption that the management may make this relative return a determining factor in its decision whether or not the new equipment should be provided. I do not question that in some cases the management may take this position, but I would point out the error involved in so doing. The proper test is not a comparison of the return on new as compared with the return on old investment, but is rather a comparison of the return on a particular new investment as compared with the return which would be obtainable from some other new investment which now might be made. Then I would point out that I believe Professor Bucky is in error in using as a factor in his computations the item of unamortized cost of old investment. The financial advantage to be derived from a new investment does not depend on the extent to which we may in the past have written off the cost of old equipment, nor does it even depend upon what was the original cost of that old equipment. Even the salvage or resale value of the old equipment will only enter into the picture to the extent that the present salvage or resale value differs from the ultimate salvage or resale value otherwise to be obtained, after due allowance for the interest factor.

Jan 1, 1930

By F. C. Langenberg, J. Chipman

Jan 1, 1959

By AIME AIME

THE difficult problem of visitors is being met by the Hudson Coal Co. at Scranton in an ingenious fashion. The Company had long made it a point to have dealers selling its coal visit the mines, whenever possible. "The excellent reaction obtained from these dealer visits brought up the question of whether it would not be possible to open one or more mines to the public, and give the consumer an opportunity of seeing for himself how anthracite is mined and prepared. Ac-

Jan 1, 1929

By Graham Bright

T HE chairman of the Mines Committee of the A. 1: E. E. for 1920-21 has had the honor of being also the chairman of a similar committee, the Mine Equipment Committee, of the A. I. M. E. It has been the endeavor during the past year to have the two committees work together since the object of these committees is very much the same. A meeting of the committees was held in Chicago in November of 1920, at which time it was decided that one of the best ways to work together would be to foster joint meetings of the local sections of the A. I. E. E. and A. I. M. E. By these meetings, it was hoped that various engineers in the local sections interested in mining subjects could be brought together and not only become better acquainted but be greatly benefited by the interchange of ideas and by the discussion of papers presented on mining subjects.

Jan 1, 1921

By Francis T. Freeland

In the West many precious-metal mines are worked in patches by lessees, under conditions which closely resemble those of what is called " tribute-work" in Cornwall.* The company has its own foreman or inspector, and usually employs the engineman, blacksmith, pumpman, and perhaps other general workmen. As an inducement to work on a new piece of ground, where no ore is in sight, the company may advance a " footage"

Jan 1, 1896

Jan 1, 1961