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HeRbeRT Haas,—(communication to the Secretary*).—Fig. I plainly shows that the comparison of the steam-turbine and Diesel-engine plants was made on a basis of 6,000 kw. continuous operating load. The tabulation of costs for an 8,000-kw. load is merely done to show the relation of increased output on the unit power costs. Both plants would sacrifice their reserve capacity, which is to insure continuous operation, if operated to generate 8,000 kw. continuously; unless Mr. Hawkins advocates the operation of one of the turbines at 33.33 per cent. overload, retaining the other as a standby, which, besides overtaxing the turbine, results in a great loss of efficiency. It would be well for Mr. Hawkins to qualify certain of his statements. Thus, under the caption "Diesel Engines, Selection of Units," he says that '(two of the largest Diesel-engine builders take the position that, in the present state of the art, they would not attempt to put out units over 1,000 kw.;" he should qualify it by saying that "two of the largest American Diesel-engine builders take the position that, in the present state of the art in the United States, they would not attempt to put out units over 1,000 kw." The reason that American manufacturers restrict themselves at present to units of that size is to be found not so much in a lack of experience in building large units as in a lack of a sufficient demand for them in the United States to justify the heavy capital outlay connected with the development of such engines. There are relatively few localities in the United States where fuel prices are as high as they are in the South-, west, and regions of high fuel prices are sparsely settled and have a very limited demand for power. Where low fuel prices obtain, steam turbines are active competitors of Diesel engines for large power plants, particularly when the station load factor is low. As most of the American manufacturers of Diesel engines work under license agreements with European manufacturers, which limit their market to the United States and its possessions and Canada, a further limitation is imposed upon them, leaving to European firms practically the entire world as a market. The greater number of power plants range in size from 300 to 1,000 hp.; the average size of the central station, on a basis of all central stations in the United States, not greatly exceeding 500 kw.; in these sizes it is hard for steam engines to compete with Diesel engines, unless fuol oil prices are excessively high, and coal prices very low, or the exhaust steam is used for heating purposes.

Jan 1, 1917

Jan 1, 1940

R. W. NEWCOMB, New York, N. Y. (written discussion *).-In this paper, the author has enumerated the various sources of error that may, under certain conditions, develop in instruments of the direct-deflection type, but through a failure to mention possible sources of error in instru-ments of the potentiometer type, he leaves the reader with a wrong im-pression. If he would carry his criticisms further and give a list of the possible sources of error on potentiometer instruments, the paper would be more complete.

Jan 12, 1919

By Theo B. Comstock

TO the large majority of visitors the unique features of the National Park are interesting chiefly on account of their novelty. Scientists of all schools may find here food for reflection, and much that is rare and marvelous; but the real, practical uses of the reservation, aside from its pleasure-giving adaptations, are not as yet fully appreciated. Since 1873, the writer has on frequent occasions expressed freely his own views upon the proper means of utilizing the Park for the best interests of science.* Some of the recommendations made have been adopted by the authorities. At the suggestion of friends I present here a brief statement of facts concerning matters which may be of advantage for visiting engineers to know, hoping that the very limited stay of the Institute may thereby be rendered a little more profitable, and that our common profession may possibly receive some benefit. First, then, it should be understood that, as in many other cases in. the West, the present routes to the Park from the south are not the most direct. The expedition of Captain (now Major) Jones in 1873 discovered a practicable route for a, wagon or railroad via the head of Wind River, through To-gwo-tee Pass and Two-Ocean Pass, by which the distance from Point of Rocks, Wyoming, on the Union Pacific R.R., to the Yellowstone Lake, is only 290 miles. Eventually, it is probable that a railway line from Cheyenne or some other point in Wyoming will be constructed, which, taking advantage of

Jan 1, 1888

By Walter Bonsack

THE CHAIRMAN.-This is the third and last session of the Institute of Metals Division's Symposium on Secondary Metals, and certainly the best of those that I have attended in the last few years. I would say that the increase in interest in secondary metals is quite noticeable by the steadily increasing attendance at these meetings. We have heard about the necessity of utilizing salvaged materials, but we still speak about them as low-grade, or down-graded materials. We still have the wrong perspective. We must willingly admit that these materials are valuable; we cannot go on using the choicest primary metals as morsels for our economic diet in a war of such unbelievable dimensions. This brings up the question-why are we so selective. The answer certainly is not that we know nothing else will do, but rather that we do not know what else will do. To be honest, we should admit our lack of knowledge concerning our complex alloys. Compared to the organic chemists, we metallurgists are very conservative, and the sooner we realize this and start to overcome it the better, because if we do not eliminate this difference, many customers of the metals business will go over to the plastics. If we take for example the development of aluminum alloys, you will see what I mean. From the binary aluminum alloys of 1920, we have progressed to ternary and quarternary alloys in the 1930's. We are only now beginning to use more complex alloys as we are forced to learn more about the effect of various elements on existing alloys. The effects of these elements should be studied now. They can be studied by two methods of approach. The usual method is to start from the base alloy and add various elements one by one in increasing amounts and study the resultant changes in properties. This is a tedious, long way. The other method which the smelters frequently use is to take the off-grade heats and study their characteristics. While the producer of primary alloys often has difficulties in alloying certain elements with the alloy under investigation, the smelter often finds them well alloyed in his raw materials and has no difficulties at all. Elements such as lead are difficult to alloy with aluminum and they tend to segregate severely. However, the amount which will remain alloyed in the metal is usually found in some "secondary" aluminum alloys. If one considers such concentration as the saturation, then by dilution with the same type of alloy, but free of such element, one can produce numerous intermediary alloys for investigation. In this fashion one is fairly certain to get uniformly spaced concentrations of the element under investigation. Similar cases probably exist with other metals. Nevertheless, the amount of work necessary to study all possible combinations is still tremendous. Necessity forces us now to utilize alloys which contain more elements than we are accustomed to. It is, therefore, necessary to study carefully the more complicated alloys. In secondary aluminum we are working and using the alloys which contain as many as 6 to 10 elements and we have learned over a period of several decades to balance

Jan 1, 1943

By R. Dawson Hall

Discussion of the paper of R. DAWSON HALL, presented at the San Francisco meeting, September, 1915, and at the New York meeting, February, 1916, and printed in Bulletin No. 105, September, 1915, pp. 2013 to 2021. R. DAWSON HALL, New York, N. Y.-The general practice in the past has been to view the roof as being somewhat subject only to shear. In fact the action of the roof under the stress of its own weight has been but little considered, not because the matter is unimportant but because it is so complicated that it has been felt that an analysis of it would not result in any conclusions definite enough to justify the inquiry. The result has been that the consideration of the subject has fallen into the hands of persons who are not experts in the study of beam and plate stress. They have been disposed naturally to view the destruction of the roof as the outcome of the simplest of stresses-vertical shear. In the lack of a careful consideration of the conditions of roof fracture it was thought that the roof consisted of a number of horizontal layers, which were each of them weak, because, no matter how strong they might be they usually lacked sufficient depth. This view of the condition of the roof would naturally lead one to expect that it would yield to bending moment, the various layers succumbing one by one to their lack of the necessary radius of gyration to meet such severe stresses. But,

Jan 5, 1916

By Felix E. Wormser

REGISTRATION started bright and early Monday morning in the Silver Corridor at the Waldorf-Astoria with Mrs. W. H. Bassett as chairman. What a registration-over 200 ladies! Several joined us from as far away as California and Washington State. Apparently they enjoy our meetings so much that present travel inconveniences didn't discourage their coming. At noon the ladies joined the men at the All-Institute Luncheon and Monday evening we had our informal dance, which is separately reported. Tuesday morning was devoted to our annual meeting at which all Section annual reports were read. At noon we were all the guests of the W.A.A.I.M.E. at a luncheon at the Port Arthur Restaurant on Mott St. in Chinatown. Many of us rode down on the old 3d Ave. elevated railway-the last of four. It, too, is soon to be torn down. The luncheon was delightfully unusual, with huge dishes of delicious Chinese food on each table. Our chairman, Mrs. Read, who lived in China in her youth chose our menu, and she chose it well, for most of us indulged so heartily that as we arose from the table we felt we couldn't eat again for 24 hours. Someone donated sherry wine, and boxes of Chinese pencils as favors. We wonder who? All owe a big vote of thanks for this lovely party to Mrs. T. T. Read and Mrs. H. A. Prosser, chairmen, and Mrs. H. W. Hardinge, Mrs. R. Hursh, and Mrs. R. L. Lloyd, vice-chairmen.

Jan 1, 1944

By G. A. Deitz, J. Halpren

The kinetics of dissolution of silver in cyanide solutions under oxygen pressure have been investigated over a wide range of conditions with a view to establishing the reactions involved and the factors which influence the rate. The results indicate that the rate is determined principally by the transport of reactants in solution to the silver surface. The thermodynamic features of the reaction with particular reference to the influence of pH and CN- are also discussed and summarized in the form of potential-pH diagrams. METALLIC silver is readily attacked and dissolved by cyanide solutions in the presence of oxygen. This reaction has long been recognized and extensively applied1 in the well-known cyanide process for the extraction of silver from its ores. While this process has been subjected in the past to a number of investigations2,3 both of a practical and fundamental nature, some features relating to the chemistry of the reactions involved, the role of oxygen, the nature of the rate-controlling step, and the effects of pH and certain reagents such as lime, are still not fully understood. It was felt that this situation justified a further investigation of the reaction, made with a view to obtaining a better understanding of its kinetics and mechanism. In the present investigation rate curves for the dissolution of silver were determined over an extensive range of carefully controlled reaction conditions. By carrying out the reactions in a pressure vessel, the partial pressure of oxygen, and hence its concentration, could be varied widely. The influence on the reaction of other variables including temperature, pH, and the concentrations of cyanide, peroxide, and other salts was also examined. The results of these kinetic studies are presented and discussed in this paper, together with a summary of available thermodynamic information relating to the possible reactions which can accompany the attack on silver by aqueous solutions of cyanide and oxygen. Chemistry and Thermodynamics of the Reaction The chemistry of the reactions of gold and silver with aqueous cyanide solutions has been the subject of several recent reviews.'." It has been proposed' that the following reaction occurs when silver dissolves in cyanide solutions in the presence of oxygen: 4Ag + 8CN- + 0, + 2H.0 -t 4Ag(CN); + 40H- [la] An equation of this form, for the corresponding dissolution of gold, was first suggested by Elsner." Bodlaender5 proposed a similar overall reaction, but suggested that it took place in two steps, 2Ag + 4CN- + O2 + 2H2O ? 2Ag(CN),- + 2OH- + H2O2 [2a] followed by 2Ag + 4CN- + H2O2? 2Ag(CN); + 20H- [3a] On the other hand, Janin- suggested that the dissolution of gold can occur with the liberation of hydrogen, rather than by reduction of oxygen. The corresponding equation for the dissolution of silver is 2Ag + 4CN- + 2H20 -t 2Ag(CN); + 20H + H2 [4a] All these reactions represent oxidation-reduction processes and may be resolved into the corresponding separate oxidation and reduction components. The oxidation step involves the formation of the argentocyanide ion and is the same for all the reactions, i.e., Ag + 2CN? Ag(CN)2 + e [51 However, reactions la, 2a, 3a, and 4a differ in the nature of the reduction steps which are, respectively, O2 + 2H2O + 4e ? 4OH- [lb] O2 + 2H2O + 2e ? H2O2 + 2OH- [2b] H2O2 + 2e ? 2OH- [3b] 2H2O + 2e? 20H- + H2 [4b]

Jan 1, 1954

By R. A. Stauffer

THE chief ore of lithium is spodumene, a lithium-aluminum silicate containing up to 3 pct lithium. The preparation of lithium salts from spodumene is costly because of the low concentration of the metal and the difficulty of separating it from the other alkali metals present. Dr. Kroll's and Dr. Schlecten's recent paper' has reviewed various methods proposed for preparation of lithium. It will be seen from this paper that the methods proposed to date have required one or another of the lithium salts as a raw material. The high cost of these salts has been the chief item of expense in the lithium metal produced. This situation has made it interesting to investigate the possibility of producing the metal directly from spodumene. When spodumene is calcined at 1000°C in the presence of lime, lithium oxide is replaced in the ore as is evidenced by the fact that it may be leached from the reaction mixture with water.2 Free energy calculations suggested that lithium oxide might be reduced with aluminum or silicon and the lithium produced distilled from the reaction mixture by heating to about 1000°C in a vacuum. These facts taken together suggested that it might be possible to prepare lithium metal directly from spodumene by heating a mixture of the ore, lime, and a suitable reducing agent in vacuum and distilling off the lithium metal as formed. THE REPLACEMENT OF Li20 IN SPODUMENE A series of experiments were undertaken to determine the ratio of lime to spodumene necessary to free substantially all the lithium oxide present in the ore. The spodumene used in these experiments was supplied by Foote Mineral Co. in the form of powder of about 200 mesh. Analysis of the spodumene was as follows: [ ] Lime (cp -200 mesh) was added in various ratios to spodumene and thoroughly mixed in a ball mill. Two hundred gram samples of spodumene-lime mixtures were charged loosely in fireclay crucibles and held at 1000°C in a gas-fired furnace for 5 hrs. The product in each case was ground to pass 140 mesh and then placed in a thimble in a soxhlet extractor. Extraction with water was carried on for 6 hrs. After this period the extract was reduced in volume by evaporation in order to precipitate dissolved lime and was then filtered and titrated with 1/4 normal hydrochloric acid. After correcting for residual calcium oxide in solution, the alkali present was calculated as lithium oxide. The results of these experiments are shown in Table I and Fig I. At lime-spodumene ratios less than 1.5, the products were invariably fused. At the ratio of 1.5 and above, the product was loosely sintered with little evidence of fusion. When the ratio of lime to spodumene was three, replacement of alkali oxides in the

Jan 1, 1947

By G. B. Craig, G. L. Montgomery

A simple technique has been developed which reveals glide dislocations in zone-refined aluminum as etch pits. The technique has been tested quantitatively by making dislocation counts on aluminum single crystals deformed in pure bending. The method has the advantage of being insensitive to the orientation of the surface under examination. A number of etchants which will reveal dislocations in annealed aluminum have been reported.'-' These etchants apparently depend on decoration of the dislocations by an impurity (probably iron) and cannot, therefore, be used to reveal fresh glide dislocations. In addition, it is unlikely that screw dislocations will be etched because of their small attraction for impurity atoms. Amelinckx6 has reported that glide dislocations located along slip traces can be revealed by fluo-rated aqua regia. This work indicated that dislocations themselves, irrespective of decoration by impurity atoms, are responsible for the etch pits. However, as a result of additional etching experiments, Wyon and Marchin7 concluded that dislocations alone are not sufficient to explain the localization of etch pits on slip lines in aluminum using chemical etch-pitting techniques. In addition, their results show that glide dislocations are revealed only on surfaces approximately parallel to a (100) axis and that not all slip systems are attacked. These observations have been confirmed by the present authors. The technique described in this article is insensitive to the orientation of the surface, and reveals dislocations on all glide systems. Fig. 1 shows a deformed region in the neighborhood of a scratch. Dislocations can be seen along three slip traces. In the present work, single crystals of zone-refined aluminum are polished for from 2 to 5 min in a chemical polishing reagent held at 100°C, as described by Herenguel and second:' H2Sol 60 pct H3PO4 30 pct HNO3 10 pet The samples are then coated with a thin oxide film by annealing in air at 450°C for 1 hr and cooling in the furnace. After deformation, dislocation etch pits are developed by immersing the specimen in the same polishing solution which is now held at a temperature of 50°C. The formation of small hydrogen bubbles indicates that etching has occurred. The sample is immediately removed from the solution. Prolonged etching results in enlargement of the pits and, in regions of high dislocation density, the overlapping and loss of resolution of individual pits. It is the experience of the authors that contact with iron will ruinously contaminate the reagent. With careful etching, dislocations separated by half a micron can be resolved optically and the method has been shown to be sufficiently sensitive to reveal dislocations produced during the pre-easy glide region of deformation, Fig. 2. A few examples of glide-dislocation configurations, as revealed by this technique, are shown in Figs. 1 to 4.

Jan 1, 1964

By John M. Sharp

John M. Sharp, Jr. (Assistant Professor of Geology, University of Missouri, Columbia, Mo.)-Geothermal gradient and surface temperature data anomalies are potentially useful tools in mineral exploration, These data, however, may reflect a number of geologic and hydrologic processes as well as the thermophysical properties of the geologic materials. The author presents a relatively simple model which may be of value in mineral exploration. The lack of consideration of other processes, however, limits its usefulness. For instance, because of erosion or sediment deposition over geologic time the land surface must be considered a moving boundary in such a model. Evaluation of this effect coupled with annual surface temperature and thermal conductivity variations can result in temperature profiles such as shown in [Figs. 4 to 7]. These effects and others, such as ground-water movement," must be considered and filtered from the data before proper interpretation is possible. Another assumption which should have been discussed is, why were the observed mean surface temperatures not used for extrapolation of the gradients in [Figs. 4, 6, and 7?] Conductive heat transport responds to the actual boundary (land surface) temperature, not to theoretical temperatures in the absence of perturbations. Benfield presents a theoretical model for calculating perturbations in the geothermal gradient for erosion and sedimentation. The temperature (T) at any time (t) and any depth below the surface (x) is given by [ ] where T is the mean surface temperature, G, the geothermal gradient, v, the rate of erosion (or sedimentation),[ ], the long-term rate of change of T0, and k is the thermal diffusivity of the rock. Using the author's values and a rate of erosion of 1.54 cm per yr for a period of 10,000 yr, a thermal profile as shown in [Fig. 10] will be generated. A thermal diffusivity of 0.0164 sq cm per sec was used, corresponding to a thermal conductivity of 0.0082 cal per cm per sec per C. In [Fig. 11], a sediment deposition rate of 3.0 cm per yr for a period of 1000 yr was used to generate the subsurface temperature profile. A surface temperature of 24.3°C was used, as specified in [Fig. 9, 7], was set equal to zero for both cases. Superposition on the generated profiles in [Figs. 10 and 11] of the annual surface temperature variation perturbation (which may be calculated in a number of ways) will yield profiles similar to those in [Figs. 4 and 7]. Similar profiles can also be produced by regional ground-water flow. Models like the author's can be of value in mineral exploration. Other processes, however, which affect surface temperatures and gradients must first be considered, calculated, and filtered from the data if anything but the crudest qualitative interpretation is to be made. Robert C. Edmiston (Author's reply)-Professor Sharp has raised three objections to my interpretation of the subsurface temperature data I collected at Silver Bell. These are: 1) No correction was made for erosion or sedimentation,

Jan 1, 1977

By Oliver S. North

Reserves of perlite rock in the western section of the United States are immense. A geological report prepared for the Union Pacific RR showed proved tonnage of over 400 million tons in southern Nevada alone. Yet the perlite industry is not large, and most of the mines are relatively small. There are indications that perlite processing, thus far largely in the hands of relatively small com¬panies, is becoming concentrated in a few large companies. For economic reasons the bulk of perlite sold in crude form has come from three or four pro¬ducers, although many individual operators have sold small quantities to limited lists of purchasers. Perlite is one of ultra-lightweight aggregates. Owing to its outstanding qualities as an aggregate, variety of uses, and ultimate economy of use, it has enjoyed considerable popularity in this country in recent years. Marked foreign interest also has been evinced in this material.

Jan 2, 1955

By John W. Tieman

Coal is a term applied to vegetable matter which, through geological processes of heat and pressure, has had both its physical and chemical properties changed. Because its chemical composition is variable, geologists classify coal as a rock rather than a mineral. Peat represents the initial stages in the development of coal, although not classified as coal itself. PHYSICAL PROPERTIES OF COAL The physical properties are concerned with the characteristics of coal in its natural state, or prior to its end use as a fuel. For example, the hardness of coal determines the maintenance cost on coal handling equipment; the specific gravity of coal determines the coal preparation techniques used in a cleaning plant as well as the capacity of coal bins, boats and size of cargo, and other coal storage facilities. The physical properties are, of course, dependent upon the chemical constituents that make up coal, and thus all properties are interrelated. Specific Gravity The specific gravity of a body is the ratio of the weight of the body in air and the weight of an equal volume of water. The specific gravity of pure coal ranges between 1.25 and 1.70, generally increasing with rank. The most important use of this physical characteristic is the part that it plays in the cleaning of coal by wet wash methods. The basic principle on which these operate is that the specific gravity of coals differs from their associated impurities and that there is a relationship between the velocity of the fall of particles in water and their density. Since the specific gravity of slate is around 2.5 and pyrite is about 5.0, pyrite and slate will fall to the bottom of a container filled with water more rapidly than coal. If the water is given a pulsating motion by

Jan 1, 1973

By AIME AIME

THE sixteenth annual meeting of the Woman's Aux¬iliary, A. I. M. E., was held Tuesday morning, Feb. 16, at the Engineering Societies Building. The meeting was well attended, there being 99 registered from the metropolitan area and 78 from the sections throughout the United States. Mrs. Sharpless, the secretary, read the minutes of the annual meeting held a year ago, after which Mrs. Bassett, the president, gave her address of welcome. Mrs. Bassett said in part: "I would like, at this time, to welcome you all to this, our sixteenth annual meeting, and to express my appreciation to all the national officers and members of the board of directors for their loyal support and for the excellent work done by the chairmen of sections and their members. It is with much pleasure that I look back upon my visits with the sections in Washington, Arizona, Northern and Southern California, Chicago, Colorado, Western Pennsylvania and Utah before I assumed the office of president. During the last year I have much enjoyed meeting with the sections in Boston, Washington and New York. It is our duty to see that the achievement for 1932 be equal to that of the year that has just passed."

Jan 1, 1932

Edwin Ludlow, the forty-first President of the A. I. M. E., died in Muskogee, Okla., on Feb. 10, 1924, after a brief illness of influenza followed by pneumonia. He was born in Oakdale, N. Y. (on Long Island), March 12, 1858, a son of William Handy and Louise (Nicoll) Ludlow. He attended Flushing (L. I.) Institute 1868-75, and Columbia School of Mines (N. Y.) where he was graduated with the degree of Engineer of Mines with the Class of 1879. After graduation, his first employment was as assistant engineer in river and harbor work on the Delaware River near Philadelphia. In 1913

Jan 1, 1924

By AIME AIME

Photo

Jan 1, 1940

By T. S. Spice, H. L. Lovell, R. W. Utley

With the increased demand for lightweight aggregate, such materials have been manufactured from slags, clays, slates and, to a minor extent, the refuse of coal preparation processes. The latter source is attractive due to current interest in eliminating air pollution and improving the unsightly appearance of refuse piles as well as potential economic advantages, if a satisfactory product can be manufactured. A study has been made relating the composition of coal refuse, expressed as washability data, and the properties of a resulting aggregate. Three different refuse samples (bituminous and anthracite) were separated at gravities ranging from 1.4 to 2.96. Their chemical composition was determined. Aggregates were prepared in the laboratory from these fractions before and after ashing, at temperatures between 1250' and 1350°C. The specific gravity, expansion and compressive strength of the products were measured. The response of the refuse to bloat is related to the chemical composition of the ash to yield a glass of desirable viscosity and to the presence of a material which will form a gas in the appropriate temperature range. Carbonaceous material within the particle is a negative factor since after the glassy phase forms, oxygen cannot enter the mass thus inhibiting bloating. Precombustion of the refuse is also detrimental since it removes substances of gas-forming capability. The fraction sinking at 2.60 yielded an aggregate which had the lowest specific gravity, greatest expansion and greatest compressive strength. The purpose of this study was to seek and evaluate possible relationships between the composition of coal refuse, as expressed by washability data and factors affecting the production of a lightweight aggregate from refuse by bloating. The study was related to an intense program in the Department of Mineral Preparation at the Pennsyl- vania State University to study the possible elimination of air pollution from coal refuse fires by producing a low-carbon secondary refuse. Another phase of this program is considering possible uses of such a secondary refuse. Thus one study was to determine if a lightweight aggregate could be produced from this new refuse material and what effect the nature of refuse beneficiation would have upon the characteristics of a commercial aggregate product. It was hoped that these studies would assist in the design of a process and in establishing the optimum specific gravities at which refuse separation could be made in respect to the production of a low grade fuel from the float product and a raw material for lightweight aggregate from the sink product. The combination of producing a saleable low grade fuel and a lightweight aggregate, while at the same time minimizing disposal costs and air pollution contributions would be attractive to the coal mining industry. MECHANISM OF BLOATING Austin, Nunes and Sullivan,1 Ehlers,3 Everhart, 4 Riley7 and others, have stated that bloating is an expansion process in which two essential conditions exist simultaneously. These are: the development of a glassy phase over a relatively wide temperature range (the viscosity of this glassy phase plays a major role in the retention of the evolved gases) and the evolution of gases (SO2, SO3, CO2 and O2) from mineral decomposition in sufficient quantities at appropriate temperatures to form a cellular structure in the mass. Unless these two "type" reactions take place at the same time or in overlapping ranges of time and temperature, cellulation will not occur. In this event, the gas will escape or the melt will be too fluid to retain it; or if retained, the cells may be too large or the walls too thin for good strength in the product. The stages that occur when clays and shales are heated in an oxidizing atmosphere may be summarized as follows: 1) Drying and removal of free water to 200°C. 2) Absorbed water dehydration period (200 to 480°C). 3) Chemically-combined water dehydration period (480 to 700°C).

Jan 1, 1965

[ ] TUNNELS TO BINS. Originally designed for tunnel work, the strong lightweight liner plates used to construct this 30-ft diameter, 31-ft high, aggregate storage bin have several advantages. Bins and conveyor to tunnels can be quickly erected in any season, for permanent service, or to be salvaged and reused. Armco Steel Corp. (16) ROLLER CHAIN: Engineering Data Book No. 2457 published by Link-Belt Co. is a comprehensive 148-page volume on roller chain and its application. Detailed engineering information covers installation, maintenance and lubrication of chains for drives, conveyors, and sprocket wheels. The book covers selection of drives to meet both standard and special installations. (17) LABORATORIES: The Fisher Scientific Co's. line of 21 basic units of standardized steel laboratory furniture is described in catalog no. 25. The Unitized line was designed to combine the advantages of custom installation with the convenience of selection, delivery and continued flexibility that goes with ready-made units. (18) PUMPS: Two similar, but functionally different types of vertical centrifugal wet-pit pumps; a heavy duty bilge pump for handling solids-free liquids and drainage; and a screenless sewage ejector, constructed to handle sewage and solids carrying liquid; are illustrated in a bulletin from Yeomans Bros. Co.

Jan 1, 1952

By Y. L. Su, R. Stefanko, Y. J. Wang

This chapter describes a new approach to the solution of stress distribution around underground openings utilizing the finite element method and employing stochastically simulated rock properties. It is well-known from extensive laboratory tests that the properties of rocks, e.g., Young's modulus and Poisson's ratio, are not single-valued but form some distribution. If the scatter of test data is attributed to the variability of the rock itself rather than due to an inadequacy in test procedure, then stress solutions have to consider these variations. Utilizing this basic philosophy, the present study was initiated. A long circular opening subjected to plane strain in a hydrostatic stress field was chosen as a specific example to illustrate this approach. The technique adopted in solving stress distributions was based on the finite element method. This method is essentially a generalization of standard structural analysis procedures in which the continuum is idealized as an assemblage of "elements," interconnected at a finite number of nodal points. It is capable therefore of handling different material properties for individual elements in the model, if desired. In this study, each individual element was assumed to be isotropic, homogeneous, and elastic. However, values for Young's modulus and Poisson's ratio were randomly varied from element to element according to an assumed frequency distribution.

Jan 1, 1970

The Sub-committee on Safety of the Industrial Organization Com-mittee of the Institute has been asked to cooperate with the National Safety Council, and has made certain recommendations to the Board of Directors of the Institute regarding ways and means of bringing about this cooperation. The National Safety Council has been in existence seven years. Its inception was at a meeting of the American Iron and Steel Electrical Engineers held in Milwaukee in 1912. The first annual congress was held in New York City in October, 1913, at which time the Council was definitely organized. Its membership now consists of nearly four thousand members, representing industrial plants, railroads, public utility companies, insurance companies, state labor commissions, Chambers of Commerce, manufacturers' organizations, etc. These members are in all states of the Union and in eleven foreign countries, and through them the National Safety Council reaches more than six million workers.

Jan 7, 1919