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By E. A. Holbrook

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

Jan 1, 1920

By B. W. Adams, R. W. Shilling

9.4-1. Basic principles. DESCRIPTION AND BASIC FUNCTIONS. The concept of inclined skip haulage is not new. The basic idea has been in use at least 400 years. The system is essentially a steeply inclined railway utilizing a hoist to pull the skips to the top or intermediate positions. Inclined skip haulage is often justified where high lifts would require long hauls for other haulage systems. The basic system types are as follows: 1. Single skip, single drum. This system is a single car pulled by a simple hoist system. 2. Balanced skip, single drum. A system utilizing two cars (skips on cables)--one overwound, one underwound-on a single drum. The dead weight of one skip and cable balances the dead weight of the other. As one skip ascends the other descends between two fixed points. 3. Balanced skip, double drum. This system is an elaboration of system No. 2, except the drums may be disengaged from one another to permit the skips to service various loading and dumping points. The preceding are major classifications subject to numerous variations. These variations may be in the skipway, skip design, loading methods, or unloading methods. A few examples follow: 1. The skipway may be standard or special railroad, an overhead monorail or cable, or a ramp for rubber tired vehicles. 2. The skip, per se, may be of varying dumping arrangements (side, bottom, etc.) or could be the box of the vehicle hauling to the skip. 3. Loading may be accomplished directly from the service unit to skip, through an intermediate loading device (e.g., a pocket), or into bins which feed the skip. Loading may be at more than one point. 4. Unloading of the skip can be simple or complex as required. Dumping may be to the haulage unit, to bins and feeders, or to a crusher and conveyor system. Dumping may take place at more than one point.

Jan 1, 1968

By B. G. Klugh

(New York Meeting, February, 1912). IN a paper before the Institute at Wilkes-Barre, Pa., June 1911,1 Mr. James Gayley discussed the application of this process to iron-bearing materials. The same author2 described the results of operations at the plant at Birdsboro, Pa. The purpose of the present paper is to present further discussion of some technical details involved in the operation of this plant, and of the theoretical and practical relations of this product to blast-furnace practice. Since Oct. 1, 1911, the Birdsboro plant has been in operation at the blast-furnace of the E. & G. Brooke Iron Co. The results have been highly satisfactory, although the material treated, being chiefly the flue-dust currently made by the furnace or taken from the accumulated stock-pile, was excessively high, and yet not uniform, in carbon, so that the desirable control or regularity of the amount of fuel in the mixture treated could not be maintained. Nothing could more forcibly demonstrate the flexibility of the process than the fact that, under these conditions, the sinter produced was, in all cases, of excellent quality. The Dwight & Lloyd process, as such, and its present highly-developed mechanical appliances were described by Mr. Gayley in the paper above mentioned. While the repetition of some particulars will be unavoidable in this paper, it will be confined to features bearing upon the metallurgical principles involved. According to the principle of the process, the finely-divided iron-bearing material to be sintered is intimately mixed with

May 1, 1912

By C. E. MacQuigg

BY and large the education of the engineer has been conservative and the reasons for this are obvious. Quite properly it has been a tradition of engineering education that facts and not fancies must be adhered to. Without a doubt, those men who formed the mold of our engineering philosophy as much as it is possible for such molds to be established-rightly held the highest standards of intellectual honesty. Fortunately, it was unthinkable to them to temporize with untried theories and naturally the men whom they trained as engineering educators carry this philosophy in turn to their students, thus handing down the tradition of stability.

Jan 1, 1943

By Robert P. Koenig

FOR the first time other than on occasion of war the people of the United States are experiencing full-scale participation in world affairs. Public concern has seldom been so involved with conditions and events beyond our own continental limits. Our interest is not wholly of recent origin. Over the years the activity of the United States as a world power and an important trading nation brought about the widening of our political interests and the progressive interrelation of our economy with that of the rest of the world. Some may see in our present phase of world-wide activity the natural consequence of our continued growth. Such observers must also be aware that within recent years our importance in world affairs has been considerably increased. For within the space of an extremely short period events have occurred that have literally jet-propelled the United States into the role of a leading participant in the conduct of world affairs. Little of the choice of this role was left to us. The decline of power in western Europe, the ascendancy between the Elbe and the Pacific shore of an obviously antagonistic force, our earnest endeavor to secure international control of atomic energy, the necessity of providing relief and rehabilitation to war-ravaged areas, and the police work that must be done in occupied territories are problems which have risen in great measure without our help-but they cannot be solved without it.

Jan 1, 1948

By G. R. Heckman, H. J. Murphy, C. T. Sims

An incestigation has been made of the effects of heat treatment and alloy composition on the long-time stress-rupture properties and structural stability of the similar nickel-base alloys Udimet-500, Lrdimet-520, and Udimet-700. Rupture test data are presented at stresses ranging from 4 to 50 ksi at temperatures from 1450° to 1900°F for times up to 14,000 hr. Ductility response is emphasized. Optical and electron tnicroscopy were complemented by X-ray diffraction analyses of extracted phases to relate microstructural stability to the observed rupture properties. Particular attention is paid to Udimet-520 since structural characteristics of this alloy appear to vary somewhat from its sister alloys. Both cast and wrought performance of Lrdimet-500 are discussed. The computerized PHACOMP calculational technique, based on electron-vacuncy theory, is discussed and related to structural stability where appropriate. Electron microscopy and microprobe techniques were used to conduct evaluation of the oxidation characteristics of Udimet-500 exposed in air for 16,100 hr. The steady advance in strength and reliability of nickel-base superalloys continues to be one of the high points of modern metallurgy. The stress capability of these materials has increased steadily, allowing higher and higher operating temperatures in the highly sophisticated aircraft and industrial gas turbines now on the market. The attendant increase in efficiency, of course, means greatly improved power output. Gas turbines for industrial and marine use have long been designed with these objectives paramount the usual design requirements in terms of time of service being 100,000 hr. High-efficiency, long-life aircraft such as the supersonic transport require superalloy engine materials with high-strength and long-time structural stability. Thus, materials studied for and operating experience from industrial gas turbines provide a good reservoir from which technology of high value to the SST program can be drawn. This study is one such case. Three prominent nickel-base super alloys—Udimet 500, Udimet 520, and Udimet 700 were extensively evaluated for industrial gas turbine bucket use. Particular attention was directed toward structural stability as a requisite property. Within the present context, structural stability is defined as freedom from the propensity to form strength-robbing or embrittling phases such as u,p,x,or Laves, and the ability to maintain useful rupture strength and ductility throughout design life. MATERIALS The three alloys, cast Udimet 500 (U-500C), Udimet 520, and Udimet 700, were chosen for detailed evaluation based on preliminary studies which indicated that U-500C and U-520 possessed comparable rupture strength capabilities, and that U -700 had a greater strength capability but somewhat poorer ductility than wrought U-500. The nominal compositions of the three alloys, along with the compositions of the heats investigated, are presented in Table I. PROCEDURE Dimensionally rejected U-520 buckets from Special Metals Corp. heat 63370 were heat-treated using the four cycles delineated in Table 11. Cycle A was investigated to determine the effects of a shortened 1700°F primary age. Cycle B was considered a "standard" treatment. Cycle C investigated a higher solution temperature in combination with a shortened primary age, while cycle D assessed the effect of the higher solution temperature alone. These heat treatments were designed to produce optimum combinations of rupture strength and ductility through maximum y' development, the development of a y' grain boundary cushion, promotion of MC carbide degeneration reactions, and agglomeration of resultant M23CB. Since one of the premises of the evaluation of U-520 was that rupture strength would be equivalent to U-500, forged U-500 buckets from Special Metals Corp. heat 62916 were heat-treated with cycles A, B, and C to provide comparison. The heat-treated structures of U-520 and U-500 are illustrated in the 8700 times electron micrographs of Fig. l. The U-700 tested was all from 3-in.-diam hot-rolled and centerless-ground rod from Special Metals Corp. heat 2-1426. Two heat-treatment cycles were employed, E and F of Table 11. Cycle E is a standard four-step, triple-age treatment intended to provide an optimum match of strength and ductility through well-developed matrix and grain boundary y', as recommended by U-700 vendors. Treatment F is a shortened , single-age cycle which could provide a significant processing cost reduction should adequate strength and ductility be maintained. Following heat treatment, rupture specimens of U-500 and U-520 were machined from the buckets and tested. Standard rupture bars of U -700 were machined from the heat-treated rod and rupture-tested. Failed and withdrawn rupture bars were prepared and examined by optical and electron microscopy. Select specimens were electrolytically digested, and the residues analyzed for carbide and topologically close-packed phases using CrKa or CoKo radiation. Of the six different U-500C heats evaluated, five were cast by Misco Precision Casting Co. and one was cast by Haynes Stellite Co. Cast-to-size rupture bars

Jan 1, 1968

By Leslie C. Richards

The competitive position of producers of industrial minerals depends upon the delivered price of their product. Freight charges are a major factor in the sales to consumers. A comparison of freight rates on movements of limestone and silica rock in the Pacific Northwest shows a wide variance in mills per ton mile for like hauls, thereby favoring some localities over others.

Jan 1, 1950

Discussion of the paper of E. S. Moore, presented at the Colorado meeting, Sep-tember, 1918, and printed in Bulletin No. 135, March, 1918, p. 687. W. F. SMEETH, * Bangalore, Mysore, India (written discussion ? )-Before dealing with the air blasts, I would like to clear up a geological point. The author states that the matrix of the conglomerate resembles a hornblende schist. This is a, misapprehension. The conglomerate

Jan 10, 1918

By L. S. Darken

IT has been known for sometime that in an ionic lattice, such as that of Ag2S or FeO, the migration velocity of the anion may differ markedly from that of the cation, the cation being usually the more mobile. It has been shown, for example, that during the formation of silver sulfide tarnish on silver, the tarnish layer grows principally by the motion of silver cations through an essentially stationary silver sulfide lattice. Similarly, the growth of wüstite scale on iron proceeds principally by motion of iron ions, this being accomplished with the aid of vacant iron lattice sites into which the iron may readily move. Likewise investigations of solid solutions of various salts show that there is usually considerable difference in the mobility of the different cations. Measurements of the mobility of various metals in liquid mercury indicate that the various metals move at different rates relative to the mercury. In view of the foregoing it seems reasonable to suppose that when any single phase solution is acted upon by a field, the atoms of different elements respond in different ways; in particular, that the force arising from a particular concentration gradient in a binary alloy would cause the atoms of one component to move with a drift velocity which is in general different from that of the atoms of the other component. The recent experiments of Smigelskas and Kirkendall1 support this viewpoint, since they found, in essence, that during diffusion in alpha brass zinc moves appreciably faster than copper. This was evidenced by the relative motion of inert molybdenum wires. Such a phenomenon is incompatible with the place interchange theory of diffusion proposed by several authors, most recently by Birchenall and Mehl.2 This theory has, however, also been questioned3.4 for other reasons, principally because of the high energy required for direct atomic interchange. The rather large difference between self-diffusivity, as determined by tracer technique, and mutual diffusivity, as determined with the aid of another element at low concentration, might also be interpreted as favoring the above idea; however, Birchenall and Mehl have pointed out that there is another possible interpretation of this difference; this is discussed later. A rather interesting and pertinent observation was made by Schwartz,5 who noticed that tungsten lamp filaments, heated by direct current, commonly fail by necking down in the region at the temperature gradient near the positive end, with a concomitant swelling at the corresponding position near the negative end. He introduces considerable auxiliary evidence to show that this phenomenon is occasioned by the motion of tungsten cations which migrate in the high temperature region from the positive end toward the negative end. The mechanism of this migration is not clearly understood. If, however, this experimental evidence be accepted, we are forced to conclude that alloying elements in the tungsten may migrate by the same or a similar mechanism, whatever it may be, at a greater or lesser rate, thus giving rise

Jan 1, 1948

By Lyall Zickrick

Numerous brands of virgin pig lead are used in the manufacture of lead and lead-alloy cable sheath for commercial cables. In changing from one brand of pig lead to another a readjustment of press operating conditions is nearly always necessary. This is due largely to different flow characteristics, and some brands extrude at a much lower pressure than others; for example, copper-bearing lead requires much more pressure than a low-bismuth lead under the same operating conditions. With the modern type of lead press the extrusion practice in general differs very little. Molten lead at a temperature of 375" to 400" C. (710" to 750" F.) is cast in a water-cooled cylinder and allowed to cool or solidify into a slug for six to nine minutes, This slug is forced into the die block and around the core tube through which the cable runs. The • die block is held at an optimum temperature by means of gas flames, usually 175" to 225" C. (350" to 435" F.). Measurements of the temperature of the cable sheath taken at the time of extrusion have covered a range of 190" to 225" C. (375" to 435" F.). According to Tammann, the rate of extrusion for a metal under constant pressure through a simple orifice is almost doubled for each 10" C. rise in temperature. Because of the irregularity of die-block construction, such a great increase is not obtained in lead-cable extrusion practice. To obtain more definite information about the effect of small percentages of metals usually present as impurities in virgin pig lead, a series of compression tests were made covering several different brands of lead and various alloys. Since the usual temperature of the sheath is approximately 200" C. as it emerges from the die block, these compression tests were all performed at 200" C. Five different brands of virgin pig lead were selected, as follows: Brand A: A desilverized western lead of very high purity. This lead contains neit,her copper nor bismuth. Brand B: A bismuth-free southeastern Missouri lead, usually containing 0.05 to 0.08 per cent copper. Brand C: A copper-free mid-western desilverized lead of very good grade, usually containing around 0.06 to 0.10 per cent bismuth.

Jan 1, 1932

By Lyall Zickrick

NUMEROUS brands of virgin pig lead are used in the manufacture of lead and lead-alloy cable sheath for commercial cables. In changing from one brand of pig lead to another a readjustment of press operating conditions is nearly always necessary. This is due largely to different flow characteristics, and some brands extrude at a much lower pressure than others; for example, copper-bearing lead requires much more pressure than a low-bismuth lead under the same operating conditions. With the modern type of lead press the extrusion practice in general differs very little. Molten lead at a temperature of 375° to 400° C. (710° to 750° F.) is cast in a water-cooled cylinder and allowed to cool or solidify into a slug for six to nine minutes. . This slug is forced into the die block and around the core tube through which the cable runs. The die block is held at an optimum temperature by means of gas flames, usually 175° to 225° C. (350° to 4.35° F.). Measurements of the tem¬perature of the cable sheath taken at the time of extrusion have covered a range of 190° to 225° C. (375° to 435° F.). According to Tammann, the rate of extrusion for a metal under constant pressure through a simple orifice is almost doubled for each 10° C. rise in temperature. Because of the irregularity of die-block construction, such a great increase is not obtained in lead-cable extrusion practice. To obtain more" definite information about the effect of small per¬centages of metals usually present as impurities in virgin pig lead, a series of compression tests were made covering several different brands of lead and various alloys. Since the usual temperature of the sheath is approxi¬mately 200.° C. as it emerges from the die block, these compression tests were all performed at 200° C. Five different brands of virgin pig lead were selected, as follows: Brand A: A desilverized western lead of very high purity. This lead contains neither copper nor bismuth. Brand B: A bismuth-free southeastern Missouri lead, usually con¬taining 0.05 to 0.08 per cent copper. Brand C: A copper-free mid-western desilverized lead of very good grade, usually containing around 0.06 to 0.10 per cent bismuth.

Jan 1, 1932

By WILLARD HAYES

(Glen Summit Meeting, June, 1911.) THE determination of the question whether the Mayari and Moa mining-claims of the Spanish-American Iron Co. have been rightly denounced under the third section of the law of bases rests on the findings in the following questions of fact: 1. Is the mineral an iron-ore? 2. Is the iron-ore a bog iron-ore? 3. Is the iron-ore ocher? 4. If ocher is present, can it be mined separately and independently of the iron-ore ? 1. IS THE MINERAL AN IRON-ORE? Since the material is shown by a large number of analyses to contain from 41. to 50 per cent. of metallic iron and less than 0.02 per cent. of phosphorus, and since it has been and is being actually used on a commercial scale for the production of iron and steel, it must be classed as an iron-ore. 2. IS THE IRON-ORE A BOG IRON-ORE? Bog iron-ore has certain invariable characteristics of chemical composition, physical appearance, geological relations, and origin by which it can always be recognized with certainty. In chemical composition, it is the hydrated sesquioxide of iron, limonite, or a mixture of limonite and other closely-related iron hydrates. It never contains the anhydrous oxides-hematite or magnetite; is never magnetic, and never contains either nickel, chromium, or cobalt oxides. On the other hand, it is invariably high in phosphorus-content. In physical appearance and texture it is a yellow or reddish-brown amorphous spongy material, and always contains water-worn sand-grains, silt, clay, and plant-remains. In its geological relations it is wholly independent of the rock

Mar 1, 1911

By Forrest F. Craig

Both early and more recent1 laboratory measurements of gas-oil relative permeabilities were made by subjecting oil-saturated cores to external gas drives. In these runs it was generally assumed that the flowing gas/oil ratio was constant at every point throughout the core. Using this assumption, the resulting equation for the gas-oil relative permeability ratio becomes A where Q is the flow rate at the producing end of the system. This relative permeability was then specified for the average saturation of the core. The assumption and resulting equation fail to recognize that in an external drive, the oil flow rate varies from zero at the injection end to a maximum at the producing end. The assumption also fails to consider the existence of a saturation gradient during an external drive. This saturation gradient is due solely to non-steady-state flow. Some authors2,3,4 have used this erroneous method of calculating relative permeability ratios from external drives. Other authors5,6,7 have used relative permeability ratios in calculating expected field performance by external drive, using Equation (1) and making the incorrect assumption that the saturation is uniform within the driven portion of the reservoir. To find the correct relation between the relative permeability. ratio at the average saturation and the produced gas/oil ratio, the insertion in Equation (1) of a factor, F, to adjust it for oil velocity gradient has been considered. The equation then takes the form Assuming that the oil velocity is directly proportional to the distance from the injection point leads to the conclusion that, for a linear system, the average oil velocity is one-half that at the producing end. Thus, the average gas/oil ratio is twice the produced gas/oil ratio, and Equation (2) is transformed into However, here again the existence of a saturation gradient is not recognized. The produced gas/oil ratio is related to the relative permeability ratio at the saturation of the outlet end of the system. It can be shown quite readily that, if the true log k,/k, saturation relationship is linear over small ranges of saturation, then d log kjko Where aaxv and u2 are the average and outlet saturations, respectively. Examination of Equation (3) shows that the factor F cannot have a single value over the whole saturation range. Another method of dealing with external drives is that of Buckley and Leverett.' Their method, which assumes no gas expansion and outlet end effects, considers fully the saturation gradient present due solely to the displacement mechanism during an external drive, and applies Equation (1) to each point along this gradient. The calculation of production history using relative permeability ratio is straightforward. However, the calculation of relative permeability ratios from production history by this method is impractical. In a recent paper, Welge,1 using an approach similar to that of Buckley and Leverett, presents a simplified method for determining the saturation at the producing end of the system. At thi; saturation, the relative permeability ratio calculated by Equation (1) applies exactly, after breakthrough of the stabilizej front. By this method, relative permeability ratios or production history may be calculated with equal ease. Use of this method as a laboratory tool in determination of relative permeability ratios by external drive requires the knowledge of the total injected fluid volume; in addition to the average saturation and producing ratio. As a preliminary test of this method of calculation, laborntory external gas drives were run on a 3% in. diameter, 11 in. long sample of Nellie Bly consolidated sandstone. This core sample had a permeability of 824 md and a porosity of 28.1 per cent. The driving fluid was air. Three different oils were used, having viscosities of 1.4, 9.8, and 125 cp, respectively. The runs were made under identical pressure differentials,

Jan 1, 1952

By H. Merton Ruth

THE northern anthracite fields, although facing the same economic problems as the southern fields, are confronted with the additional problem of fast dwindling reserves of anthracite which can be conventionally and economically won. The mining of coal which remains in thin beds and the recovery of pillars from areas heretofore considered unrecoverable, either by reason of cost or surface restriction, pose problems of in- creasing importance to the economic life of the northern field operations. Successful approaches have Been made to this problem and other work is being performed that holds promise. There exists in the northern anthracite field millions of tons of solid coal, the recovery of which has not been too successful due to the following inherent operating faults: inability to concentrate producing areas; the great quantities of rock to be cut and handled, lack of consideration of proper sequence and speed of second mining, and the continued use of the mine car as the basis of payment. A mining system that has successfully solved these major problems has been in operation in the Scranton area since 1944. Over 1% million tons have been produced from veins varying from 3 to 4% ft thick by this method, which is known as the multiple panel-triangular system-conveyor mining.

Jan 1, 1950

By HUGH E. McKinstry

OPENING the sessions of the Mining Geology Committee, the program on postwar mineral controls drew a larger attendance than any other session of the entire meeting. In view of its general interest, the papers of this session, or a substantial portion of them, are printed elsewhere in this issue. Whether control of mineral resources can help to promote peace, how controls could be applied and to whom, are questions so far-reaching that naturally no pat answer was agreed upon. In fact the discussion took on something of the flavor of a debate between those who favor strict control and those who felt that attempting to ration nations in peacetime would defeat its own ends. Discussion from the floor emphasized the difficulties in administering any international control and the $64 question, that no one cared to answer, asked by a courageous young lady who was induced to mount the rostrum for the purpose, was whether the United Nations should exchange mineral controllers to police each other.

Jan 1, 1944

By G. L. Oldright

THE metallurgist is familiar with the rapid development of concentration -by flotation and smelting in the reverberatory in recent years, brought 'about chiefly by the exhaustion of' bodies of .rich, coarse, direct smelting ore. Geologically speaking, in many porphyry-copper districts, the richer contact or replace let deposits surrounding 'the main ore-forming igneous intrusion have been exhausted, and it is necessary to beneficiate the copper minerals disseminated throughout the mass of the intrusion itself. The organization of great companies to treat such low- grade ores on a large scale and the practices resulting from the necessity for an economic method of treatment 'are among the most prominent metallurgical developments of the past decade. It is interesting to note the effect of the present trend of practice on the inter-relationship of the concentrator and smelter, on the constituents of the smelter charge, and on smelting in general.

Jan 1, 1925

By C. A. LINDBERG

Several new methods have been developed on the Iron Range to remove the material adhering to truck bodies in freezing weather. A machine known as a Gradall, incorporating the features of digging both above and below the horizontal, digging angle of blade control, full revolving, travel almost anywhere, and operated by one man, has proven successful in trials at body cleaning. Several of these units are in use with great saving in box-cleaning costs and improvements in efficiency of the truck operation with full capacity boxes. In addition to their winter use, the same machines have been used for ditching and excavating in the summer with great saving. The latest method of combating this freezing problem is to carry the exhaust from the engine through the body, making use of the tremendous heat that is now being wasted. To do this, the present wood sandwich which is used between the bottom of the box and the wear plate is removed and replaced with angles or channels run lengthwise of the box and spaced to permit gases to flow between or through them and also provide a good sup- port for the wear plate. The channels or angles are cut a little short on each end to form a cross passage that permits the gases to flow through the area. In the front end, openings are made in the wear plate and connect to a manifold created by welding a plate across the whole front of the box, spaced from the original end by the original vertical reinforcing angles at that point. The body being described is for a Euclid truck which is the only truck that has been adapted to this body-heating idea to date. At the rear of the truck, the holes from the cross passage are made in the bottom plate of the body and lead into a triangular-shaped body cross member under the scoop end of the truck.

Jan 1, 1949

By George A. Laird

I. INTRODUCTION. THIS old and once famous district played, through its enormous production of silver and gold, an important part in the history of the State of San Luis Potosi. According to a pamphlet prepared under the direction of the Governor of the State, Sr. Don Blas Escontria, and presented to the visiting members of the Institute during the Mexican meeting of 1901, this district is situated 20 km. east of the city of San Luis Potosi, in a range of mountains of moderate height, extending 135 km. N. and S., and 16 km. E. and W.; and the mineralized area hitherto developed is about 600,000 sq. m. The history of the district,. as given by the record dated 1778, and formerly kept in the San Francisco convent, says that it was discovered in 1575 by Sr. Don Pedro Irarte, and adds that the city of San Luis Rey de Francisco del Potosi received its name (in allusion to the famous Potosi mines in Bolivia) by reason of the remarkable productiveness of its gold- and silver-mines in the first period of their exploration, during which they paid to the Crown, as " quintos " (the fifth part of the product), $97,000,000, as appears from the accounts of the royal treasury. The amount of the quientos paid during the " bonanza period " of 80 years was $72,000,000. The larger sum first mentioned probably represents a longer series of years. But either will suffice to indicate the great wealth of the mines. In 1663, the decadence of the industry began with the caving¬ in of several mines, concerning which the record of 1778, al¬ready cited, says, in substance, that on Good Friday one of the owners in the enterprise, in view of the unfavorable prospect of a lawsuit in which he was engaged, set fire to the timbers supporting the underground galleries and workings of the San

Jan 1, 1905

By Michael J. Messel

OF the various minerals that occur in fibrous form known as asbestos, chrysotile is the variety most in demand for commercial uses, and, last year, over 683,000 tons of the various grades were produced in Canada and United States, exclusive of African and Russian production, which figures are uncertain. Production has not been able to keep up with the increased demand, and an acute shortage exists. Canada, Russia, and Africa are still the most important producers. However, Russia consumes most of its production at home and exports very little. The United States consumes over 60 pct of the total production and produces only about 4 pct of the total from deposits in Vermont and small quantities from Arizona. This paper will review mainly, some of the more recent developments concerned with the extraction and processing of this fibrous mineral for various industrial uses, such as textiles, insulation, building materials and brake linings.

Jan 1, 1949

By E. R. Smith

ANALYSIS of the requirements for gun perforation equipment suitable for penetrating casing and cement showed that these points would be involved: (1) Powder charges electrically detonated under high fluid lieads and at remote distances. (2) Selective firing of sliots in sequence. (3) Sufficient velocity for the bullet to penetrate at least two strings of seamless casing and all cement beyond the strings. (4) Heat-treatment of steels to withstand great pressures and penetration. (5) Esclusiorl of fluid under extremely high hydrostatic pressure. (6) Stranded steel wire line acting as weight - suspending and current - carrying medium. (7) Firing controls operated above the surface. (8) Determining gun depth and suspended weight by means of the wire line. (9) Portability for field use.

Jan 1, 1936