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By C. J. Delisio

The basic concept of tunnel boring has not changed since the late 1800's. R. Stanley of Great Britain obtained a Canadian patent as early as December 1891. Mr. Stanley's machine was a device that consisted of a rotating wheel equipped with drag-type teeth; it had a means of thrusting the cutterhead against the face or heading; it had a means of clamping or gripping the machine in its bore; it had a means of collecting and depositing the cuttings into a screw-type conveyor located near the invert of the tunnel. It even had a means of varying the speed of the forward motion of the machine to suit different hardnesses of rock encountered. This description essentially fits the latest tunnel-boring machines being built today. In short, there has been no significant advance in the basic concept in 70 to 80 years. It may well be that no significant change can be expected for some time into the future. Today's machines, while still basic in concept, offer many advances aimed at faster tunneling. Among these are 1 ) improved cutters, 2) guidance and steering devices, 3) dust-control devices, and 4) mechanisms to aid in installing tunnel supports. CUTTERS The most important part of a hard-rock tunnel borer is the cutter. If the cutter can cut the rock, it is a boring machine. If the cutter cannot cut the rock, no other part of the machine can. When Jarva, Inc. decided to build a machine, the first problem was to find a good cutter. In our search, we looked at most of the cutters on the market. We selected Reed Drilling Tools' cutter because the design of their cutter was aimed at hard-rock tunneling. We feel that they build the best cutter available and provide the best possible service to their customers. As tunnel-boring machine design advanced, the transition from drag bits to roller bits was natural because harder formations required a roller bit, and it is the goal of all mole users to bore harder formations. Roller bits

Jan 1, 1970

By R. H. Winn

In this paper a heterogeneous carbonate reservoir is considered as a succession of layers of formations of radically different porosities, permeabilities, water saturations, and rock matrix types; i.e., the heterogeneity is vertical rather than radial to the wellbore. Presumably each layer is more or less homogeneous. To determine the "net oil in place" in this reservoir it is desirable to know the porosity and water saturation of each layer. In addition, the section must be subdivided into that which will produce oil, that which will produce water, and that which will produce little or nothing. In numerous wells drilled in these reservoirs radioactivity surveys, guard electrode surveys, and caliper surveys have been made. These logs have been compared with core analysis data, when available, and the analysis of the surveys compared with production data. This study, still in progress, is intended to provide improved analytical techniques if such are possible. This paper is a progress report on the work. DETERMINATION OF POROSITY The neutron-gamma log has long been recognized as a measure of hydrogen concentration.1,2,3 In reservoirs that are free of clay, shale, or other hydrogen containing matrices, it has been accepted as a measure of porosity.4,5 Empirical methods to relate relative neu-tron-gamma intensity to porosity are often employed." To provide a more precise determination of porosity from the neutron-gamma log each instrument is calibrated immediately prior to each survey by a method which refers all tools to a hydrogenous cylinder. To insure stability a calibration check is made after each survey. These calibration records are printed as an integral part of the log that is recorded in standard counts per second. A detailed description of the calibration procedure is available in the literature.' The procedure employed insures that each Survey is numerically reproducible within the limits of statistical variation. To relate the standard neutron counts per second to porosity and hole size, records were made in test wells constructed of blocks of limestone. The porosities of the blocks were accurately measured and the blocks completely saturated with fresh water. Fig. 1 presents some of the results obtained in these test wells.' The lines shown in Fig. 1 were obtained by deriving an empirical equation relating the 11 points shown so that the relationship may be projected to larger and smaller hole sizes. A detailed description of the tool is available in the literature.' Field tests indicate that the tool is adjacent to the wall of the hole most of the time when the surveys are made in uncased holes drilled with saline muds. In this circumstance porosity may be calculated from Fig. 1 if the hole size is known. When fresh muds that form thick mud cakes are employed, the centralizing effect of the mud cake must be considered and the porosity determination is less reliable. In cased holes the combined effect of variations in hole diameter and the unknown eccentricity of the casing in the hole may make porosity determinations extremely unreliable. In any event, an accurate knowledge of hole size is essen-

Jan 1, 1958

By Lawrence H. Van Vlack, Otta K. Riegger

Periclase-type oxides were examined microscopically after being exposed to siliceous liquids. The rate of grain growth was found to be inversely proportional to the grain diameter. Grain growth proceeds more rapidly at higher temperatures, but is retarded by increasing liquid contents. aMag-nesiowiistites with higher MgO contents grow less rapidly than those with higher FeO contents. The growth rate is reduced by the presence of a second solid phase. The silica-containing liquid penetrates as a film between the individual magnesiowus tite grains. This is independent of time, temperature, amount of liquid, or the MgO/ Fe0 ratio. When present, olivine and spinel-type phases can provide a solid-to-solid &apos;&apos;bridge" between magnesioustite grains. THIS paper presents the results of a study of the microstructures of periclase type oxides in the presence of a silicate liquid. The purpose was to learn more about the effect of service factors such as 1) time, 2) temperature, and 3) liquid content upon A) grain growth, and B) liquid location among the solid grains. This study was prompted by the fact that periclase refractories are known to have very little solid-to-solid contact when the phases which are present are limited to periclase and liquid. Such a micro-structure gains industrial significance because it permits fracture during service when stresses are applied at high temperatures. The details of ceramic microstructures have not received extensive attention. This is in contrast to the extensive attention given to a) the phase relationships pertaining to refractory compositions, and b) the details of the microstructures of comparable metallic materials. A brief review will be made of the pertinent phase relationships and microstructural considerations in general, as well as of refractory compositions. a) Phase Relationships. This investigation was limited to those compositions in which (Mg, Fe)O was the solid phase. MgO and FeO form a complete series of solid solutions. Pure MgO has the name of periclase. The related FeO structure is called wustite. Both have the NaC1-type structure: however, wustite possesses a cation deficiency so that the true composition is Fe<10 even in the presence of metallic iron. The phase relationships involving solid (Mg, Fe)O and a silicate liquid are shown in Fig. 1. In this case. the liquid is saturated with (Mg, Fe)o. There-fore its SiOz content is below that encountered in orthosilicate liquids. As a consequence the liquid phase specie:; are primarily the following ions: and 0-&apos; plus occasional Fe+ ions. Two features are of importance: a) the liquid contains relatively small species and b) the liquid contains large quantities of the same species as the solid. viz., Fig. 2 shows the system, FeO-SiOz, which will be used in some of the discussions that follow. This diagram is the right side, vertical section of Fig. 1. Here, as pre\iously, the composition at the FeO end of the diagram is nonstoichiometric, varying from Feo.950 when the liquid oxide is in contact with the solid iron, to about Fe 0, when the solid oxide is in equilibrium with an atmosphere of equal proportions of CO and C02 at the solidus temperature. The Fe/O ratio will be maintained in wustite in the presence of SiO,. However, the FeM/Fe++ ratio in the liquid will be lower because of the effect OIF the SiO, on the activity of the FeO. With the addition of MgO to wustite, the over-all composition (IvZg, Fe)@, has a value of x lying between 0.9 and 1.0 when the COz/CO ratio is 1.0&apos;. b) Microstructures. In general, published attention to refractory microstructures has been directed toward the phase analyses that accompany compositional variations. This is illustrated by Harvey6 in his work on silica brick and by wells7 in his work on periclase brick. In each case, a series of altered zones is encountered which provides a sequence of phase associations. If due consideration is given to reaction kinetics, such an examination reveals phases that are compatible with equilibrium studies. Admittedly, however, it is often necessary to determine more complicated polycomponent systems to account for all the phases present.8 Relatively little attention has been given to microstructural geometry in ceramic materials. Certainly less attention has been given to this aspect of ceramic microstructures than to the size, shape, and distribution of the constituent phases in metals. Burke has pointed out that the grain size of oxides follows the same growth rules as for metals, viz.,

Jan 1, 1962

By Culver, Richard S.

In spite of the widespread interest in rock bolt research, relatively little is known about the critical region surrounding the bolt anchor. In analyzing the stress distribution around an opening resulting from rock bolt support, it is commonly assumed that the bolt is fixed at a point far enough from the surface so that the anchor does not influence the performance of the bolt. Furthermore, a bolt anchor is assumed to per- form satisfactorily if it will hold the design load with a minimum amount of load relaxation, commonly called bleedoff. From the standpoint of the design engineer both of these assumptions are reasonable, but they ignore the fact that the extremely high stresses in the region of the anchor are capable of generating fractures in the rock. Lang estimated the bearing stresses for a slot and wedge anchor on a one-inch-diameter bolt to be as high as 125,000 psi. This paper describes a more thorough analysis of the magnitude of the stresses around the anchor and the nature of the potential fractures that might result.

Jan 1, 1968

THE opening session* was held in the hall of the Franklin Institute, on Tuesday evening, June 20th, President Holley in the chair. The President introduced. Mr. Franklin B. Gowen, who addressed the Institute as follows MR. PRESIDENT AND GENTLEMEN : It has been made my pleasant duty to welcome you to the city of Philadelphia, but in so doing I shrink, with some natural reluctance, from appearing before an audience so much better fitted than I am to cope with the subjects which are usually presented to your association, and I can assure you that no trembling neophyte, first venturing within the groves of the Academy, or walking, with sacred reverence, in the gardens of Plato, felt more natural dread at the consequence of his own temerity than I do in appearing before an audience composed of gentlemen belonging to a scientific society of which I am but too sensible that until now I have been a member only in name. In olden times, upon entering a temple sacred to the worship of any deity, it was customary to lay some offering upon the altar, and, in following this custom, it will be my duty, before entering upon the more pleasant part of the task which is assigned me, to call your attention to a subject with which I have been somewhat familiar, and which is entirely within the scope of your investigations, in the belief that I may throw out some hints or some suggestions of a pro¬cess that may be fully developed by some of you, and eventually lead to the introduction of that which may be of service to the human race. The satirist who described the philosopher whom he met, as engaged in the process of extracting sunbeams from cucumbers, * A joint discussion of the subject of Technical Education, by the members of the American Society of Civil Engineers and the American Institute of Mining Engineers, was held in the hall of the Franklin Institute, on Monday evening, June 19th, and Tuesday morning, June 20th. This discussion has been printed in a separate pamphlet by both societies.

Jan 1, 1877

By F. Keller, A. H. Geisler

Some of the important changes that take place in the structure of aluminum alloys are largely submicroscopic in character. This is especially true of the changes that accompany age-hardening and recrystallization. Although improved metallographic practices have been helpful in indicating some of these changes indirectly, results are limited by the resolving power of optical microscope lenses. The electron microscope, however, provides a new and important means for investigating the fine structure of metals in a range not possible heretofore. It is anticipated that this microscope will yield new and useful information to metallurgists when suitable techniques are developed to utilize its very high resolving power. Several unique methods have been devised to permit the examination of the structure of opaque samples by the electron microscope. These are all based on the principle of producing a very thin film that represents the prepared surface of the opaque metal sample, which can be examined in the transmission microscope; however, the available methods fall into three categories, depending on the manner in which the film is obtained. With the oxide-film method developed by Mahl3-17 a very thin surface layer of the metallographic sample is converted into oxide by a thermal, chemical or anodic treatment. After removal from the metal sample by one of the special techniques described by Evans,19 this oxide film is examined in the electron microscope, and is found to portray the structure of the original metal surface. Films formed on aluminum,8,17 nickel,7 iron 3,8,9 and a nickel-beryllium alloy" by heating; films formed on iron 8.9 by chemical action; and films formed on aluminum3-16 by anodic oxidation, have been examined. The other two are more recent methods developed principally in this country; they consist in making the thin film in the form of a mold or replica of the surface contour of an etched sample. With the negative replica method the thin film is made directly on the sample; with the positive replica method it is made on a negative reproduction of the sample. With both methods, variations in the contour of the metal sample, caused mainly by etching, produce variations in the thickness of the surface replica. Because of the direct dependence of the amount of scattering of the illuminating electrons upon the thickness of the film penetrated, only the variations in thickness of the replica are responsible for tones in the electron image. Negative replicas are made by forming a thin film of some suitable material directly on the polished and etched metal sample, and derive their name from the fact that after removal from the sample they have the high and low points in the sample reversed, as shown in Fig. I. Nega-

Jan 1, 1944

Do not write until you have something to say. Think first; then write. In order to be understood, you must know what you wish to say. Clear writing is the consequence of clear thinking. Therefore consider your subject well before you begin to write; ruminate on it; marshal the salient facts in your mind; saturate yourself with the ideas you wish to express and with cognate ideas; then express yourself deliberately. If you are bubbling over with your subject the words will come, but you might as well expect to sail without a breeze as hope to give life to words without the living thought. Here I may advert to the fact that among the uneducated it is a common expectation to acquire the knack of writing without taking the trouble to study the art of literature. I overheard a woman in a suburban train remark to her neighbor: "I&apos;d like to be able to write well without stopping to think about it". She was one of many that would like to do a thing well without the trouble of thinking; but it cannot be done in respect of anything to which thought is essential. The possession of a good voice does not justify a person in expecting to sing successfully to a large audience; before singing in public one has to master the technique of singing; one has to learn first how to breathe properly, how to enunciate, and many other things. The successful singer is an artist, not a megaphone. Most of us would regard a man or a woman without any training in the art of singing as a fool or an impostor if he or she were to give a public concert, yet we do not recognize the equal foolishness and imposture of persons that write books before they have studied the technique of writing. That is why so many books are unreadable, and why many books by clever men are difficult to read. They start to write books before

Jan 1, 1931

By ROY BERENTZ

MANUFACTURE is the transformation of material by the application of energy and power. The energy of a man exerted throughout a day is equivalent to about one horsepower-hour of mechanical work an amount which can be purchased for less than 2c. It is evident that manual labor is uneconomical if mechanical energy can be applied effectively, or without disproportionate expense. Since manual energy is relatively so costly, economy demands that mechanical power be employed so as to reduce the human effort connected with mining operations to a minimum. Power, like other commodities, is most efficiently produced in large quantities. Mechanical transmission, once prevailing, is being rapidly superseded by electric drive. There are many reasons for this change; such as increased production, ease and accuracy of control, convenient application, ease of moving, etc.

Jan 1, 1930

By N. A. Ziegler

A CERTAIN amount of interest has been indicated recently in the resistance to oxidation at high temperatures of iron-aluminum alloys (rich in iron). Hautman1 published a paper in. which some interesting results are given. According to his paper, only alloys containing at least 8 per cent aluminum indicate a marked improvement in their resistance to oxidation. At about this aluminum content, however, alloys become brittle, which considerably reduces their commercial value. About two years ago the author, performed a series of experiments, the results of which are presented here. A series of iron-aluminum-carbon alloys was prepared by melting electrolytic iron, aluminum and high-carbon iron alloy in an induction vacuum furnace.2 The list of these alloys is given in Table 1. Each alloy was forged in the ordinary way to

Jan 1, 1932

By Basil B. Zavoico

Production of crude oil in the U. S. S. R. during 1939 is estimated at, 226,111,000 bbl., as compared with 219,778,000 bbl. in 1938, an irlcreasc of 2.88 per cent but some 6.00 per cent under the planned output. During the past year a major readjustment took place in Russian oil fields, with the Grozny district falling into the third place, its former place having been taken by the fields of the Maikop-Kuban area of northwestern Caucasus. Production continued to grow in the Ural-Volg:t district and further large increases in this province in the coming years are certain. The drilling operations continued to be most unsatisfactory, falling far behind the plan, possibly as much as 25 per cent undvr the set objectives, and thereby interfering with the production plans, mora particularly since the Soviet oil industry is still based primarily upon the production from the naturally flowing wells without any proration whatsoever rather than upon stabilized production from either prorated oil wells or those operated with various mechanical lifts. The year 1939 started with the fulfillment of the drilling programs to the extent of about 90 per cent, but the situation rapidly deteriorated arid by the second half drilling programs were being fulfilled only to the extent of 60 per cent or less. Such breakdown in drilling operations was possibly due to poor equipment, which has not been able to stand increasing demands upon it, and this is substantiated by the rccent orders plaeed in the United States by the Soviet Government for some 60 drilling rigs of the latest design. Production Baku District.—-The fields of the Apshcbron Peninsula (Baku district) made a notable progrress during the past year and were able slightly to increase their production, to 166,000,000 bbt. as compared with 164,692,-000 bbl. during 1938. The c.rnphasis of production in the Baku district remained on the flowing wells, about 20 per cent of the total number of wells flowing about 70 per cent of production. During 1939 some 550 wells were complr.tcd in the Baku district with active rigs averaging

Jan 1, 1940

By Basil B. Zavoico

Production of crude oil in the U. S. S. R. during 1939 is estimated at, 226,111,000 bbl., as compared with 219,778,000 bbl. in 1938, an irlcreasc of 2.88 per cent but some 6.00 per cent under the planned output. During the past year a major readjustment took place in Russian oil fields, with the Grozny district falling into the third place, its former place having been taken by the fields of the Maikop-Kuban area of northwestern Caucasus. Production continued to grow in the Ural-Volg:t district and further large increases in this province in the coming years are certain. The drilling operations continued to be most unsatisfactory, falling far behind the plan, possibly as much as 25 per cent undvr the set objectives, and thereby interfering with the production plans, mora particularly since the Soviet oil industry is still based primarily upon the production from the naturally flowing wells without any proration whatsoever rather than upon stabilized production from either prorated oil wells or those operated with various mechanical lifts. The year 1939 started with the fulfillment of the drilling programs to the extent of about 90 per cent, but the situation rapidly deteriorated arid by the second half drilling programs were being fulfilled only to the extent of 60 per cent or less. Such breakdown in drilling operations was possibly due to poor equipment, which has not been able to stand increasing demands upon it, and this is substantiated by the rccent orders plaeed in the United States by the Soviet Government for some 60 drilling rigs of the latest design. Production Baku District.—-The fields of the Apshcbron Peninsula (Baku district) made a notable progrress during the past year and were able slightly to increase their production, to 166,000,000 bbt. as compared with 164,692,-000 bbl. during 1938. The c.rnphasis of production in the Baku district remained on the flowing wells, about 20 per cent of the total number of wells flowing about 70 per cent of production. During 1939 some 550 wells were complr.tcd in the Baku district with active rigs averaging

Jan 1, 1940

By Richard P. Rothwell

The anthracite coals of Pennsylvania are all mined from large veins. A seam less than four feet. in thickness is generally considered as unworkable, those from which most of the coal now comes being from 8 &apos;to 30 feet thick. The system of mining employed is, almost without exception, that known as " chamber and pillar work;" that is, the coal is taken out of chambers of from 18 to 30 feet in width, and pillars of from 12 to 20 feet are left between these to support the roof. In general, the entire thickness of the seam, even

By Edwin B. Johnson

The success of self-fluxed sinter in enhancing the operation of the blast furnace during the past few years has reasonably led to the assumption that the use of self-fluxed pellets might result in even greater furnace efficiencies. A great share of development work in agglomeration has been directed towards techniques related to the production of self-fluxed pellets, but no appreciable tonnage of self-fluxed pellets had been produced on a commercial scale until this past year when The Cleveland-Cliffs Iron Co. produced 35,000 tons of such pellets by the grate kiln system at the Republic mine during the period May 21-June 5, 1962.

Jan 3, 1963

By E. P. Abrahamson II

The effect of transitiorz element bitzary solid solution additions upon the recrystallization temperature of columbium has been investigated. The elements Mn, Fe, Co, Ni, W, Re, and 0s OWY the yecystallization tempel-aturye, while Ti, V, CY, zr, Mo, Ru, Rh, Pd, Hf, Ta, W, Ir, and Pt mise it. A correlation is kloted between the rate of chatzge of recyystallization tewaperature with atomic hercent solute and the free atom electron configuration of the solute element. The work of Abrahamson and Grant1 has indicated a correlation between the free atom ground-state electron configuration and the change in brittle-ductile transition temperature per atomic percent solute in chromium base alloys. A similar correlation was observed for the change in the recrystallization temperature of iron base alloys by Abrahamson and Blakeney and Abrahamson. It was also observed that the limit of rapid change in recrystallization temperature also Correlated with the electronic configuration of the free solute atom. A further study by Abrahamson4 established the generality of the phenomenon by yielding similar results for vanadium base dilute alloys. It has been inferred that a peri- odicity might be expected with changes in the free atom electron configuration of the solvent element. This study is the third set of transition base metal systems to be studied. It is the object of this and further studies on transitional metal systems to detect any systematic variations in the observed correlation which might contribute to the understanding of the electron interactions which are evidently exhibiting themselves. PROCEDURE All alloys were made using 99.9 pct Cb with 0.030 Ta, 0.016 0, 0.0025 H, 0.003 Mo, 0.021 Fe, 0.005 C, and 0.002 N. The solute elements were 99.9 pct pure. According to the published binary phase diagrams5 and metallographic examinations at X750, all additions were in solid solution. The alloys were arc melted and remelted 6 times in the form of cubic 400-g buttons under an argon atmosphere. They were then hot forged at 1200oC to 0.6-in. diameter, annealed for 3 hr at 1200o under argon, and furnace cooled. The specimens were then machined to 0.400 -in. diameter. Grain size was checked and found to remain essentially constant at 150 i 30 grains per sq mm. The specimens were then cold swaged to 0.187-in. diameter, yielding 46 i 1 pct cold work. All alloys were chemically analyzed for the major solute. Analyses of random samples indicated that the impurity content remained at the values of the starting material. Tungsten contamination was held to 0.007 pet.

Jan 1, 1962

ALLERTON S. CUSHMAN, Middletown, Ohio (written discussion*).¬ This subject is one to which I have given much thought and study and which I have frequently discussed informally with Mr. Cain and others. I have long been convinced that the gaseous elements, either combined or entrained (occluded), in steel play a much more important role than is ordinarily admitted. This is probably due to the difficulties encountered in the accurate quantitative estimation of gases, some of which Mr. Cain has referred to, as well as to the fact that, considered from the weight-percentage basis, gas content is measurable only in hundredths or even thousandths of 1 per cent. Volumetrically, however, the results ob-tained by modern research are startling, to say the least. Baraduc-Muller,1 as cited by Mr. Cain, pumped out of 1000-lb. ingots of basic Bessemer steel 2100 l. of gas. or about 75 cu. ft., at normal temperature and pressure, per ton of steel. In other words, we are to understand that Bessemer steel normally carries about fifteen times its own volume of gas. According to Baraduc-Müller&apos;s table of results, which is given here-with, carbon monoxide, nitrogen, and hydrogen are important consti-tuents of Bessemer steel, the latter gas being undoubtedly formed by the

Jan 11, 1919

By R. A. Deju, R. B. Bhappu

The basic structural unit of all silicate minerals is a tetrahedron with a silicon atom at the center and four oxygen atoms at the corners. The oxygen-silicon distance is about 1.6 & and the oxygen-oxygen distance about 2.6 &. The different types of oxygen-silicon frameworks in the various silicates are based entirely on the combinations of the tetra-hedral oxygen-silicon groups through sharing of oxygen atoms. In recent years, infrared spectroscopy has permitted estimation of the ratio of the ionic character of the oxygen-silicon bond to be a few times that of the oxygen-carbon bond and the ratio of electro-negativity of the two bonds has also substantiated this finding. On this basis, it is generally accepted that the oxygen-silicon bond is the strongest one occurring in silicate minerals. As the oxygen-silicon ratio increases from quartz to the olivines, a greater percentage of the oxygen bonding power is available for bonding to cations other than silicon. Hence, with an increasing oxygen-silicon ratio, there is increasing oxygen-to-metal bonding. Upon the fracturing of a silicate mineral crystal, the oxygen-metal bond, which is almost entirely ionic in character, should break more easily than the stronger oxygen-silicon bond, resulting in a greater number of unsatisfied negative forces on the surface. If, then the mineral is immersed in a liquid containing hydrogen ions, these negative forces should tend to be neutralized by hydrogen ions from solution, resulting in a change of the pH of the solution. An increase in the degree of adsorption of hydrogen ions is to be expected as the oxygen-silicon ratio in the crystal structure increases. This study attempted to correlate the oxygen-silicon ratio for various representative silicate minerals to the adsorption of hydrogen ions. Experiments to determine the effect of surface area on this adsorption and to investigate the effect of surface iron were also conducted. It is believed that such studies of the surface properties of silicate minerals will supply pertinent information about their behavior in froth flotation systems. EXPERIMENTAL PROCEDURE Ion Exchange: Carefully selected, hand-picked samples of the minerals investigated were dry-crushed in a ceramic ball mill and sieved to obtain a minus 100 plus 200-mesh sample. The sized samples were then run through the electro-magnetic separator to remove any iron-bearing particles. A 10-g sample of each mineral was placed in 100 ml of freshly deionized water previously adjusted to a pH of 3.50 with HCl. The beaker containing the sample and the water was placed under a bell jar from which the air was displaced at once by nitrogen gas from a tank. All experiments were carried out in a nitrogen atmosphere. The sample and solution were stirred gently but continuously during the entire experiment, the stirring speed being kept about the same for all runs. Changes in pH were followed with a Beckman Zeromatic pH meter and recorded on a

Jan 1, 1967

By Moore, Richard B

PROBABLY no other metal excites as much interest, among both scientific men and the general public, as radium. This is due partly to the high cost of radium salts and partly to the peculiar properties of the element. Since radium-bearing ores were discovered in the United States, the interest of American scientific men has been stimulated and, at the present time, more radium is extracted and refined in this country than in all the rest of the world together. HISTORY The property of radioactivity was discovered, partly by accident, by Henri Becquerel, the French physicist, in 1896. He was experimenting with certain fluorescent substances in order to find, if possible, a connection between fluorescence and the recently discovered Y-rays. Among other chemicals which possess the property of fluorescence, he was using

Jan 8, 1918

By Roger Holmberg, Kenneth Mäki

This paper describe; open pit studies where blasting damage introduced in the remaining rock has been investigated. Results from two open pit mines are described and discussed. Parallel performed laboratory experiments, where simulated blasting damage has been introduced into samples before shear strength testing took place, are also reviewed. These studies are tied together in order to throw some light upon how the blasting damage influences the slope stability. A mathematical model is also described which will make it possible to optimize the blast design for a specified damage zone in the rock mass.

Jan 1, 1983

By JAMES GAYLE

(Presented at the Washington meeting, May 3, 1905, and simultaneously sent to the Iron and Steel Institute, for presentation at the meeting of that Society in London, May 11, 1905.) IT is to be regretted that the data respecting the use of dry-air blast, which was presented to the Iron and Steel Institute at its meeting in the United States, in October, 1904, should. have been restricted to the period from August 25th to September 9th inclusive, and from September 17th to 30th inclusive. In order to present the paper at all it was found necessary to limit the record of operations to the period above stated. In the discussion of the paper it would appear from the conclusions of some participating therein, that they have been placed at some disadvantage in considering the economies obtained through the use of dry-air blast, by reason of the data covering such a short period. It is the purpose of this communication to present in detail the record of operations of the Isabella Furnaces from November, 1904, to March, 1905, inclusive, as shown by the furnace-records. The month of October, 1904, is not included, as the furnace using dry-air blast was stopped several times for repairs, and while the record was a very good one considering these interruptions, yet it was not a continuous one. The record for Furnace No. 1 using dry-air blast, and the comparison with Furnace No. 3 using natural air for the month of November, 1904, is set forth in Table I. By a reference to my former paper it will be noted that the month of November is the beginning in this country of the winter period, when the atmosphere decreases rapidly in humidity. The month of October being the transition month in the autumn and April in the spring, and furnaces using natural air approach more closely, from November on, to the conditions obtained by the use of dry-air blast. The data given in

Jul 1, 1905

By Walter S. Tower

IN making comparisons of steel industries, one country with another, the convenient common denominator is annual capacity to make raw steel in the form of ingots. It is always necessary, however, to remember that there are different methods of figuring such capacity. For most countries no official figures on capacity are available, and the only authentic data on production are now six or eight years old. But in spite of those limitations on the accuracy of statistical comparisons, any flaws in the figures are probably not serious enough to alter materially the larger conclusions which may be drawn from them.

Jan 1, 1944