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I PRESIDING OFFICER At all business meetings of the Institute the President, or, in his absence, the First Vice-President, or, in the absence of both of them, any other Vice¬ President or Director, chosen by the meeting, shall preside At all other meetings of the Institute the President, or, in his absence, one of the Vice-presidents shall preside If none of these be present the meeting shall elect a Chairman The President shall do and perform such other duties as may from time to time be assigned to him by resolution of the Board of Directors of the Institute II ORDER OF BUSINESS At each business meeting of the Institute the order of business shall be as follows 1 Reading of minutes of preceding meeting 2 Report of the President 3 Report of the Treasurer 4 Report of the Secretary 5 Election of Directors 6 Reports of Standing Committees 7 Reports of Special Committees 8 Special Orders 9 Miscellaneous business This order of business may be changed at any meeting, by a vote of a majority of the Members and Associates present At all sessions of the Institute, other than business meetings, the order of proceedings and the time of adjournment shall rest in the discretion of the presiding officer

Jan 1, 1923

By F. E. Jaumot, R. L. Smith

Self-diffusion in zinc at temperatures below 200°C has been studied using both single crystal and polycrystal samples. Anomalous results were obtained for single crystal samples, the data indicating that in some cases grain boundary diffusion predominated. These anomalous results are presumed to be due to low angle lineage boundaries in the single crystals. When volume diffusion occurred in either single or polycrystal samples, the values for the diffusion coefficient were as much as several orders of magnitude larger than would be expected from high temperature data. ONSIDERABLE work has been done on self-^-*diffusion at temperatures in the neighborhood of two thirds of the melting temperature (in OK) and higher, but very little has been done at lower temperatures. This is particularly true of self-diffusion in single crystals. This paper reports work on self-diffusion in zinc at temperatures below 200 °C where both polycrystalline and single crystal samples have been used. The measurements were made using both the sectioning and absorption techniques. The experiments on diffusion at low temperatures were initiated primarily for three reasons: to obtain data from single crystal diffusion covering a wide range of temperatures, to obtain values of the activation energy for grain boundary diffusion, and to obtain, if possible, a lower limit to the temperatures at which the absorption technique may be used. It is possible to determine whether volume or grain boundary diffusion predominates at low temperatures by analyzing the manner in which the concentration of the diffusing atoms varies with the depth of penetration. The analysis is possible only for the sectioning technique. For volume diffusion and for the boundary conditions of the present experiment, the curve of the logarithm of the concentration, C, vs the square of the penetration depth, x, is a straight line with the slope proportional to — 1/D. If grain boundary diffusion predominates, Fisher' has shown that a curve of In C vs the first power of the penetration depth should be a straight line. This linear dependence of concentration on depth has been observed experimentally by several investigators. (See, for example, refs. 3 and 4.) Following Fisher's analysis, the grain boundary diffusion coefficient can be written as where 8 is the grain boundary width, D, is the volume diffusion coefficient at the temperature involved, t is the time of diffusion, C is the concentration of diffusing material, and x is the depth of penetration. A more general analysis employing the same model as Fisher's but with fewer assumptions has been given by Whipple.' In contrast to Fisher's analysis the more general analysis of Whipple does not always yield a straight line relation between In C and x. Recently Turnbull and Hoffman have discussed both analyses and have applied the Fisher-Whipple model to a more refined dislocation model of the grain boundary. They have also discussed the possibility of a large effect of grain boundary direction on diffusion. In the case of the absorption technique, for which results are also given, one simply gets a value for the diffusion coefficient with no indication of the predominating mechanism. Experimental Techniques Single crystals of 99.99+ pct Zn were grown using a modified Bridgman method. Polycrystal samples were prepared in three grain sizes (small, about 4 mm2; medium, about 9 mm'; and large, about 25 mmz) by quenching, air cooling, and furnace cooling. The grains of the polycrystalline samples tended to be columnar, with some preferred texture such that the c-axis was inclined at about 20" to 25" from the normal to the diffusion face, particularly in the medium and large grain size samples. The samples were cut from the rod, polished, and heavily etched, and faces cut accurately parallel using a jeweler's lathe. They were again etched to remove the lathe smear and annealed for 3 hr at 250" to 300°C. After annealing, they were etched, examined, and the orientation determined by Laue back reflection photographs. They were then electroplated with Zn. The plated surfaces were examined for uniformity; nonuniform coatings were removed by etching and the samples replated without additional preparation. For the diffusion anneals, the samples were placed in pairs, with active faces together, in evacuated Pyrex tubes. Constant temperature baths were used, and the variation in temperature did not exceed ±l°C, Diffusion runs were made at l00°,

Jan 1, 1957

By A. K. Mukherjee, John E. Dorn

The effects of strain rate and temperature on the critical resolved shear stress for (321)[111] slip were determined for the silver-rich CsCl type of intermetallic compound AgMg. The flow stress increased only slightly as the test temperature was first decreased below room temperature; a rapid increase in the flow stress was obtained with yet further decrease in temperature from about 250' to 4OK. The effect of both the temperature and strain rate on the flow stress over the low-temperature range could be rationalized satisfactorily in terms of the Peiwls mechanism when the deformation was controlled by rate of nucleation of pairs of kinks. IN spite of the well-documented interest of metallurgists and engineers concerning the mechanical behavior of intermediate phases and intermetallic compounds, very little definitive information is available on this important subject. As recently summarized by westbrook,1 only limited and modest progress has been made thus far in elucidating the details of the mechanism of plastic deformation for the intermetallic compounds; the available information largely concerns phenom-enological descriptions of empirical observations and experimental facts, principally with reference to poly crystalline aggregates. The present report on the elucidation of the rate-controlling mechanism for slip in the bcc structure of AgMg is part of the comprehensive program of a systematic investigation on the mechanical behavior of intermetallic compounds. The intermetallic compound AgMg has a CsCl type of lattice structureZ and is completely ordered up to its melting point of 820c3 This material was selected for our present investigation because of its simple crystal structure, moderate and congruent melting point, ordered structure persisting up to the melting point, and some solubilities of the constituent elements, which could be expected to help in the growing of single-crystal specimens. Whereas previous investigations on the properties of AgMg include hardness,*"6 slip systems,7 tensile flow stress of polycrystalline specimens,' and electrical resistivity,4 the current investigation will be directed principally at elucidating the rate-controlling dislocation mechanism responsible for slip in single crystals at low temperatures. It will be shown that the strain rate is consistent with a model involving the rate of nucleation of pairs of kinks by the Peierls mechanism for plastic deformation. EXPERIMENTAL TECHNIQUES Single-crystal specimens of the AgMg intermetallic compound were prepared and tested as follows: 1) A master alloy ingot of AgMg was produced by melting and chill casting the high-purity silver (99.995 wt pct) and high-purity magnesium (99.997 wt pct) in an induction furnace under a helium atmosphere. 2) Sections of the above-mentioned ingot were placed in a graphite mold containing a spherical cavity in which a single-crystal sphere of 1 in. diam was grown under helium by the Bridgman technique. 3) The operative slip systems were investigated at room temperature on a singlecrystal of AgMg, from measurements of the angles made by the slip traces on the two surfaces of the specimen, which were at 90 deg to each other. The investigation confirmed that the AgMg compound undergoes slip primarily in the (321) plane and in the [Ill] direction, but a small amount of secondary slip was also noticed in the (112) (111) system. No slip was observed in the (110) planes. 4) The single-crystal sphere, mentioned earlier, was oriented in a graphite mold containing a cylindrical cavity of 3/8 in. diam above the spherical receptable to give the angle xo = 45 deg between the axis of the cylindrical bar and the normal to the slip plane (321), and the angle AO = 45 deg between the slip direction [Ill] and the axis of the bar. Oriented single-crystal bar seeds were produced by melting, under a helium atmosphere, a polycrystalline bar in the cylindrical cavity above the oriented spherical seed and by growing an oriented single-crystal bar from the seed. 5) Finally, oriented single-crystal specimens were grown from these cylindrical seeds. 6) The cylindrical specimens were machined in a High-Tension Spark Cutting unit to give a 2-in. gage length. The spark-machined gage section was elec-tropolished in a bath containing 200 ml of H3PO4,

Jan 1, 1964

By Samuel S. Wyer

Bethlehem Meeting, February, 1906 THE following abbreviations have been used in the text:¬ Am. MF. and Iron World. American Manufacturer and Iron World, Pittsburg, Pa. Can. Min. Rev. Canadian Mining Review, Ottawa, Can. Cass. Mag. Cassier's Magazine, New York, N. Y. Col. Eng. Colliery Engineer, London, Eng. Col. Guard. Colliery Guardian, London, Eng. Eng. and Min. Jour. Engineering and Mining Journal, New York, N. Y. Eng. News. Engineering News, New York, N. Y. Engr. Engineering, London, Eng. J. I. and S. I. Journal of the Iron and Steel Institute, Lon¬don, Eng. Jour. W Soc. of Engrs. Journal Western Society of Engineers, Chicago, Ill. Lond. Eng. The Engineer, London, Eng. Mines and Min. Mines and Minerals, Scranton, Pa. North of Eng. I. M. E. North of England Institute of Mining Engineers, Newcastle-on-Tyne, England. Oester Zeitsch f. Berg u. Hüt. Oesterrcichische Zeitschrift für Berg. und Hüttenwescn, Vienna, Austria. Pract. Engr. Practical Engineer, London, Eng. Proc. I. C. E. Proceedings Institution of Civil Engineers, London, Eng. Trans. A. I. M. E. Transactions American Institute of Mining Engineers, New York, N. Y. Trans. A. S. M. E. Transactions American Society Mechanical Engineers, New York, N Y Trans. Fed. I. M E. Transactions Federated Institute Mining Engineers, Newcastle-on-Tyne, England. Trans. I M E Transactions Institute Mining Engineers, Newcastle-on-Tyne, England.

Mar 1, 1906

By J. J. Rutledge

THE first method of working coal mines in the middle western states, more particularly in Illinois, Indiana and Missouri, was by means of the so-called single-entry method. In this method a single main passageway, or entry, was driven in the coal seam. with no parallel passageways, and from this pas-sageway or entry there were turned at intervals sim-ilar cross-passageways or entries, and from these cross-passageways, if the coal seam worked lay fairly horizontal, rooms were turned right and left. These crude methods of working were followed when the com-panies opening the mines were small and of very limited capital, and when the demand for coal was small and irregular. The principal desire was to produce coal in the short-est possible time and at the cheapest price. The chief evil resulting from such method of working was de-fective ventilation, although there were other serious drawbacks. There were then few or no good mining laws and no restrictions on those operating the coal mines. The hours of labor were long, the wages low, and the miners accordingly worked hard. All the coal was either sheared or undercut with a pick by hand. Very little solid shooting and no machine mining was done. What little air entered the mine, openings was introduced through the entries or. headings and thence conducted through the rooms by means of curtains; in many cases, as the workings became more exten-sive, the number of curtains added so materially to the mine resistance that ventilation was extremely in-efficient. Shots were fired by the miners at any time during the working shift and consequently there was more or less powder smoke or fumes in the mine work-ings all day long. Moreover, the working days were much longer than at present. The fine, dry coal-dust falling from the miners' picks while they were shear-ing or undercutting the coal filled the mine atmosphere and was taken into the lungs of the mine employees.

Jan 2, 1927

By J. E. Tobey, David R. Mitchell, J. H. Kerrick

DETAILED knowledge of purchase specifications established by coal consumers is essential to the successful design and operation of a coal-preparation plant. ANTHRACITE Specifications should be considered by both the consumer and the producer as guide posts outlining a certain path for both to follow. Plants differ, therefore specifications must differ to meet the varied requirements. Specifications are not of themselves a "cure all" or an assurance of complete satisfaction in fuel utilization. Specifications should not be regarded as a license to engage in an orgy of buying any and all coals that may happen to fall within their limits. This would lead to the indiscriminate mixing of coals which may vary in their burning characteristics. Different coals of equal grade tend to be individualistic in their burning characteristics. Rather, specifications should be used to help simplify coal selection, to reduce the actual number of coals used over a given period; in other words, to have a stabilizing influence on coal or customer turnover. In the final analysis, the use of too many coals per year in a plant is costly to both the consumer and the producer. Too many sources usually result in higher operating and maintenance costs for the consumer and higher sales costs for the producer. Finally, the statement included in the report accompanying the com¬prehensive Coal Selection Charts prepared by the Coal Committee of the National Association of Purchasing Agents, and released in 1938, is significant. This Committee worked diligently for a period of 15 years seeking to find a scientific and reliable method for selecting coals. The two following paragraphs are quoted from its report: More important is the fact that no ready-made classification or set of specifications can possibly replace the judgment and resourcefulness of an experienced combustion engineer or fuel technologist, nor the usual need for full scale plant tests under the exact conditions of use before a final decision is made ...

Jan 1, 1943

By Thomas T., Read

ALTHOUGH the first colonists in the area that is now the A United States, whether Spanish, French or English in nationality, were usually keenly interested in the possibilities of mineral wealth, it is a curious and interesting fact that none of them happened upon the mineral deposits that eventually were to make this the greatest mineral-producing country; up to 1800 it would probably have been rated as rather poor in minerals. Spanish explorers traversed the southeastern United States with- , out finding the Appalachian gold deposits that aroused so much interest in the early nineteenth century; Coronado sought in vain for the seven golden cities of Cibola; and the important gold \ deposits of California were not discovered until the political sovereignty of the region had passed from Mexico, which had held it for three centuries. The French also held Canada for nearly two centuries (and the British for another century) without finding the mineral deposits in Ontario and Quebec that now are so important. Though they knew of the copper of the Keweenaw peninsula, the lead ores. of Wisconsin and Missouri, and the coal of Illinois in the seventeenth century, these deposits were all too remote for exploitation. In the area held by Great Britain, iron smelting was planned at Jamestown as early as 1619 and was actually begun at Lynn, Mass., in 1643. The industry grew slowly, at first, but had reached considerable importance before the Revolution. Commercial bituminous coal mining began about 1750 in Virginia but anthracite mining in Pennsylvania was not started until 1800. As a result there was naturally little interest in the technical aspects of mineral prodnction here before 1800 by any except the few people who were actually engaged in it. Students of natural science were much interested in minerals, however. The activities of those who rank as geologists are so thoroughly covered in

Jan 1, 1941

By G. Derge, Ling Yang, John Henderson

Self-diffusion coefficients of aluminum have been measured by the capillary reservoir technique in liquids of the CaO-SiO2-Al2O3 system containirg equimolar portions of CaO and SiO2, in the temperature range 1400o to 1520oC. For the melt containing 6.0 mole pct Al2O3 the results can be expressed by the equation D = [(4.3 * 0.3) x 104] exp [(-85,000 * 17,500)/RT]cm~sec-'; for the melt containing 12.5 mole pct Al2O3, by the equation D = (5.4 i 0.2) exp [(-60,000 * 10,00O)/RT] cm2sec-: A concept of the constitution of these melts has been developed which proposes that the ratios O/(Si +Al) and Al2 O3/CaO determine the dominant species present. In recent years considerable work has been done on the system CaO-SiO2-A12O3 with a view to elucidating the structure of liquids of this system. Conductivity,' electromotive force, 3 density,4 and activity5 measurements have all contributed to an understanding of the problem, but as yet there is no entirely satisfactory theory that can account for all the observed experimental results. In principle, measurements of self-diffusion coefficients should give further information which is not obtainable in other ways. Self-diffusion coefficients for calcium, silicon,6 and oxygen7 have been measured. The present investigation extends the series of self-diffusion coefficient measurements to include aluminum and develops a concept of constitution for liquids of this system which is compatible with all the observed experimental results. EXPERIMENTAL The technique used in the measurement of the self-diffusion coefficient of aluminum was the capillary-reservoir method,8 A126 being incorporated in the melt contained in the capillary and inactive aluminum in the reservoir melt. This method was chosen because it minimizes convection currents' in the diffusion zone. It has the further advantage that the boundary conditions are such that a slight modifica- tion of Anderson and saddington's8 solution of Fick's Law yields an equation which requires measurements only of the length and the initial and final average specific activities of the solidified melt within the capillary. where t is the diffusion time, Co is the average specific activity of the melt contained in the capillary at t = O, C is the average specific activity of the melt contained in the capillary at t = t, 1is the length of the capillary, and D is the self-diffusion coefficient. The equation is of somewhat different form than those previously applied to high temperature diffusion studies because the specific activity of the melt in the reservoir was negligible both before and after diffusion. The diffusion apparatus is shown schematically in Fig. 1. It consisted of a silicon carbide resistance furnace containing the inactive melt in a graphite crucible, internal dimensions 7/8 by 4 in., enclosed in a 1 1/4- by 1 1/2- by 30-in. McDanel tube. A 3/8-in. McDanel thermocouple sheath to which graphite radiation shields and a graphite protection tube were affixed, was used to hold the capillaries. By moving this sheath through a rubber seal at the top of the McDanel tube the capillaries could be lowered into or raised out of the melt. Temperature was measured with a Pt-Pt 13 pct Rh thermocouple which was calibrated periodically against a standard couple. The furnace temperature was controlled to ± 5°C through the thermocouple immersed in the melt. Temperature variation over the depth of the melt was less than ± 3°C. The inactive melts were prepared from pure native quartz, assaying better than 99.9 pct SiO2, A.R. grade A12O3 and A.R. grade CaCO,. The same quartz and CaCO3 were used in preparing the active melts, the

Jan 1, 1962

By Walter F. Bradley

CLOSE to 300 members and guests were registered at the Regional Meeting of the Institute in San Francisco. Oct. 3-6, and many other mining men were present at some of the sessions, but failed to register. Headquarters were at the Palace Hotel. Technical papers for the Metals Session were sponsored by the San Francisco Section, whereas the program for the Industrial Minerals Session was arranged by the Southern California Section. Walter W. Bradley, Chairman of the San Francisco Section, opened the General and Metals Session, introducing President Buehler, who gave a hearty welcome to those present. Clyde M. Eye, of the. Benguet Consolidated Mining Co., presented the first paper, entitled "The Economic and Strategic Value of Philippine Metals to the United States." In closing, he urged. that this country retain and control the Philippines because their large

Jan 1, 1935

By Bruce R. Lipin

Chromite, the only ore of chromium, occurs almost exclusively in mafic-ultramafic rocks and their weathering products. However, not all kinds of mafic-ultramafic rocks are favorable hosts for possible low-grade chromite deposits. For instance, chromium-bearing basalts are not favorable because they commonly contain <0.3% Cr203, and chromite is almost always less than 50 mp in diameter, if it is present at all. Chromite-bearing ultramafic rocks in stratiform and alpine complexes tend to be either ore grade (>25% chromite) or very low grade (<2% chromite); intermediate rocks are scarce. In most complexes, large tonnages exist only in the <2% chromite rocks and the composition of the chromite in those rocks may be unsuitable for metallurgical use. Some nickel laterite districts contain more than lo8 tons of material with 2.0 to 5.5% Cr203, and hence, chromium could be a byproduct of nickel in some laterite districts. In addition, some chromiferous sand placers may contain tens to hundreds of millions of tons of material between 2 and 5% Cr203

Jan 1, 1983

By S. Yukawa, M. J. Sinnott

A high resolution autoradiographic study of the diffusion of a nickel isotope (NP3) into copper in the temperature range of 650° to 925°C, with particular emphasis on grain boundary diffusion, has been made. The extent of grain boundary diffusion is a function of the grain boundary angle and the diffusion temperature. The ratios of the grain boundary diffusion coefficient to the lattice diffusion coefficient ranges from 104 to 105. The activation energy for grain boundary diffusion decreases with increasing grain boundary angle. STUDIES and reviews&apos;-8 of metallic diffusion have indicated that grain boundary diffusion is a common phenomenon but quantitative studies of the many variables involved are not numerous. The present work was concerned with determining the influence of the crystallographic orientation of the grain boundaries and the temperature on the extent of boundary diffusion of nickel into copper. The study involved essentially three steps: 1—the production of grain boundaries of known crystallographic orientation, 2—the determination of the extent of diffusion into the boundaries, and 3—the analysis of the resulting data in terms of the usual diffusion concepts. The grain boundaries investigated approximated the simple tilt variety having l° of freedom. They were produced by controlling the solidification from a melt of Cuprovac (a high purity vacuum-melted copper obtained from Vacuum Metals Corp.) of a pair of seed crystals so that the bicrystals of copper produced had a common <100> axis. By rotating one seed crystal relative to the other, a simple tilt boundary was produced. The angle of rotation between the two crystals is the grain boundary angle 8, or what is sometimes termed the misfit angle. In all, some 16 boundaries ranging from 2" to 72" in 5" to 10" steps were investigated. The crystallographic orientations were measured with the use of both X-ray and optical goniometric techniques. The <100> axes in the crystals were found to be parallel within 2" to 3" with the exception of one crystal (8 = 12") in which the axes were 6" from being parallel. All bicrystals showed evidences of sub-grain structures. Laue analyses showed that these subgrains differed in orientation up to a maximum of 2". Because of these variations, and some curvature in the boundaries, the grain boundary angles listed are actually average values and deviate from the 1 o of freedom boundaries. The stripping film technique of high resolution autoradiography was used to detect the diffusion of the nickel isotope into the grain boundaries of the bicrystals of copper. Kodak experimental permeable stripping film with an emulsion layer 5 u thick

Jan 1, 1956

By Louis V. Bender

AfteR investigating the work of coal-dust fired reverberatories of the Canadian Copper Co., at Copper Cliff, Ontario, the management of the Washoe Reduction Works decided to experiment with and ascertain the advantages of using coal dust as a fuel in their reverberatories. Consequently, during the month of June, 1914, reverberatory furnace No. 8 was changed in order to use powdered coal as a fuel. The results obtained by this method of firing are gratifying and show a decided saving in cost of smelting as compared to grate firing with lump coal. The furnace, as remodeled, is 124 ft. long by 21 ft. wide, and varies in height from 8 ft. 6 in. at the back end to 5 ft. 7 in. at the skimming end. The general construction of the furnace is similar to that of the other furnaces at this plant. There are no side doors to this furnace, as it was thought that with the present arrangement for feeding no "fettling" or "claying" would be required. The interior of the furnace can be inspected through the burner port holes, after shutting off the burners and giving a few seconds&apos; time for the gases inside the furnace to clear away. The charging is done on either side of the furnace from longitudinal hoppers, extending a distance of 74 ft. from the back end of the furnace. Leading from the hoppers into the furnace are 6-in. pipes, spaced 191/4 in. apart, through which the charge is intermittently dropped. The charge is kept well above the slag line at all times; in this way the side walls are protected and no fettling is needed on this portion of the furnace. The remainder of the furnace requires fettling. After operating for three months, we found that the bricks were eaten into along each side wall from the skimming door back to the point where the charge had been dropped. The depth of this cutting away was 8 in. close to the front end and gradually tapered to zero at a distance of 50 ft., and was greatest on the side of the furnace having the larger flue connection. Hoppers will be put in for the entire length of furnace, from which fettling material will be dropped, to prevent this cutting. After the run of three months, the roof was in excellent condition. At the back of the furnace the bricks were not cut into at all; at 30 ft.

Jan 1, 1915

By Floyd Kelley

THE literature of the last decade is rich with information relating to the cause and means of control of grain growth in pure metals, but is deficient concerning the role diffusion plays in grain growth, although during this period many new products that depend on diffusion for their properties and success have been developed. Among these are cementation products, produced by calorizing, chromizing, and carbonizing, or by mixing, pressing, and sintering powdered metals such as Syke&apos;s iron-molybdenum die material, Genelite, and Elcon Metal (copper, tungsten) etc. This is a fertile field for new developments, but before it can be util-ized to the fullest extent there must be a thorough investigation of the processes by which diffusion and grain growth take place. Grain growth plays no small part in the process and certainly the physical properties of these products depend largely on the grain size and state of equilibrium produced. The field of investigation does not end here, but may be extended to the effect of diffusion on impurities, segregations and dendrites in the broad field of ferrous and non-ferrous metallurgy. A number of years ago the author investigated several of these cases and noted, with striking regularity, the pronounced effect of diffusion in promoting recrystallization and grain growth. An example of this phenomenon is given in his paper on chromizing1 which contained photomicrographs of large radial or columnar crystals produced by diffusion of chromium in the solid state. Another manifestation of this effect was discussed by Austen,2 who showed the part hydrogen plays in the decarburization of steel and the effect of diffusion upon the grain structure.

Jan 1, 1928

By Henry Mulryan

Diatoms are microscopic aquatic plants of the order Bacillariaceae. They are unicellular plants with skelctons made up of amorphous opaline silica. The skeletons show highly ornate, complicated geometrical designs. Diatoms live in water virtually everywhere. They are found in clean sea water, brackish water, and fresh-water lakes and ponds. When conditions are right, diatoms propagate by subdivision in huge numbers. Alkalinity, temperature, and the presence of high concentrations of silica in the water largely control diatom life. When the diatoms die the skeletons drop to the bottom of their habitat to form oozes of varying thicknesses. Diatomites Diatomite, or diatomaceous earth, is composed essentially of the siliceous remains of the diatoms, although other organic skeletons are also present, especially in sea-water deposits where radiolaria, sponges and silico-flagellates are common. Impurities are generally carbonaceous material, fine-grained silt, volcanic ash and dust, and occasional coarse grains of sand. Diatomites are marine, brackish, or fresh-water, depending upon types of diatoms and their method of deposition. Diatoms More than 8000 species of diatoms have been named and classified. Some are definitely classified as to their habitat; some are so well recognized as to their living conditions that they can be stated to be diagnostic types, and when encountered in a deposit determine the origin of the deposit. Some of the commoner types of diatoms found in the freshwater diatomites on the Pacific Coast are: Cymbella lanceolata Agardh Fragilaria virescens Ralfs Encyonema prostratum Ralfs Diatoma vulgare Dory Surirella biseriata Brebison Eunotia major Ehrenberg Amphipleura pellucida Kützing Stictodiscus niagarac Ehrenberg Gomphonema geminatum Lynberg Melosira granulata Ehrenberg Epithemia turgida Kützing

Jan 1, 1942

By Henry Mulryan

Diatoms are microscopic aquatic plants of the order Bacillariaceae. They are unicellular plants with skelctons made up of amorphous opaline silica. The skeletons show highly ornate, complicated geometrical designs. Diatoms live in water virtually everywhere. They are found in clean sea water, brackish water, and fresh-water lakes and ponds. When conditions are right, diatoms propagate by subdivision in huge numbers. Alkalinity, temperature, and the presence of high concentrations of silica in the water largely control diatom life. When the diatoms die the skeletons drop to the bottom of their habitat to form oozes of varying thicknesses. Diatomites Diatomite, or diatomaceous earth, is composed essentially of the siliceous remains of the diatoms, although other organic skeletons are also present, especially in sea-water deposits where radiolaria, sponges and silico-flagellates are common. Impurities are generally carbonaceous material, fine-grained silt, volcanic ash and dust, and occasional coarse grains of sand. Diatomites are marine, brackish, or fresh-water, depending upon types of diatoms and their method of deposition. Diatoms More than 8000 species of diatoms have been named and classified. Some are definitely classified as to their habitat; some are so well recognized as to their living conditions that they can be stated to be diagnostic types, and when encountered in a deposit determine the origin of the deposit. Some of the commoner types of diatoms found in the freshwater diatomites on the Pacific Coast are: Cymbella lanceolata Agardh Fragilaria virescens Ralfs Encyonema prostratum Ralfs Diatoma vulgare Dory Surirella biseriata Brebison Eunotia major Ehrenberg Amphipleura pellucida Kützing Stictodiscus niagarac Ehrenberg Gomphonema geminatum Lynberg Melosira granulata Ehrenberg Epithemia turgida Kützing

Jan 1, 1942

By Henry Mulryan

DIATOMS are microscopic aquatic plants of the order Bacillariaceae. They are unicellular plants with skeletons made up of amorphous opaline silica. The skeletons show highly ornate, complicated geometrical designs. Diatoms live in water virtually everywhere. They are found in clean sea water, brackish water, and fresh-water lakes and ponds. When conditions are right, diatoms propagate by subdivision in huge numbers. Alkalinity, temperature, and the presence of high concentrations of silica in the water largely control diatom life. When the diatoms die the skeletons drop to the bottom of their habitat to form oozes of varying thicknesses. DIATOMITES Diatomite, or diatomaceous earth, is composed essentially of the siliceous remains of the diatoms, although other organic skeletons are also present, especially in sea-water deposits where radiolaria, sponges and silico-flagellates are common. Impurities are generally carbonaceous material, fine-grained silt, volcanic ash and dust, and occasional coarse grains of sand. Diatomites are marine, brackish, or fresh-water, depending upon types of diatoms and their method of deposition. DIATOMS More than 8000 species of diatoms have been named and classified. Some are definitely classified as to their habitat; some are so well recognized as to their living conditions that they can be stated to be diagnostic types, and when encountered in a deposit determine the origin of the deposit. Some of the commoner types of diatoms found in the fresh-water diatomites on the Pacific Coast are: [Cymbella lanceolata Agardh Fragilaria virescens Ralfs Encyonema prostratum Ralf s Diatoma vulgare Bory Surirella biseriata Brebison Eunotia major Ehrenberg Amphipleura pellucida Kutaing Stictodiscus niagarae Ehrenberg Gomphonema geminatum Lynberg Melosira granulata Ehrenberg]

Jan 1, 1939

By R. W. Heckel

The conzpaction of metal powders is analyzed through density-pressure curves as a three-stage process — die filling, individual particle motion, gross compact deformatim. The densification occurring during each of these stages is evaluated quantitatively. The amount of densification in the first and second stages is primarily a function of particle geometry. The densification taking place in the third stage is dependent mainly upon the material. AT the present time the densification of powders during compaction is usually described by terms such as "compactibility," "compressibility," and "compression ratio." Schwarzkopfl has proposedthat compactibility be defined as the minimum pressure needed to produce a given green strength, while compressibility be used to indicate the extent towhichthe density of a powder is increased by a given pressure. Compression ratio is generally defined as the ratio of the compact density obtained at a given pressure to the apparent density of the loose powder. 13alshina found that the pressure imposed on a compact affects the relative volume of the compact according to the following relation: hP= - LV + C [ll where: P is the applied pressure, V is the relative volume of the compact, Ratio of the specific volume of the compact to that of the material without porosity. Lisa constant described as the modulus of pressing and is determined by the slope of a plot of h P vs V, and C is a constant which is determined by the intercept of a plot of InP vs V. Several drawbacks of the Balshin analysis may be noted from Fig. 1, which is a plot of pressure (loga-

Jan 1, 1962

Quarrying and crushing 500 tons of limestone plus burning some 240 tons of limestone per day are the two initial phases in the production of borax, soda ash, sodium sulfate and related chemicals at Stauffer Chemical Co.&apos;s plant in Westend, Calif. These processing steps have been upgraded in recent years by the installation of new primary and secondary crushers, an 8 x 340-ft rotary kiln plus kiln feed, control and cooling components-all designed and manufactured by Traylor Engineering and Manufacturing Division of Fuller Co. As a result of this new equipment, a new product- quicklime-has been added to the West End product family and considerable reductions have been realized in fuel and manpower costs.

Jan 1, 1965

By Edel Moldenke

Burma has long been known for its ruby, tungsten, and tin deposits, and, lately, for having the largest lead-zinc mine in the world, the Bawd-win mine of the Burma Corpn. All the coal used, however, is imported from Calcutta; this is a bituminous coal of about 11,000 B.t.u., 24 per cent. ash, and costs about $8 per ton. Bituminous coal has not, thus far, been found, but many lignite deposits are known. The most promising lignite deposits are in the Namma field, Fig. 1, situated in the Northern Shan States of Upper Burma, about 30 mi. south of Lashio, the terminus of the Burma Railway, 750 mi. north of Rangoon. The

Jan 1, 1922

Dec. 2, American Mining Congress, annual membership meeting, University Club, New York. Dec. 2, Society for Applied Spectroscopy, Socony-Vacuum Training Center, New York City. Dec. 4-6, AIME, Electric Steel Furnace Conference, Hotel William Penn, Pittsburgh. Dee. 5, Atlanta Meeting of Southeast Section, AIME, Ansley Hotel, Atlanta. Dec. 7-10, American Institute of Chemical Engineers, annual meeting, Hotels Cleveland and Carter, Cleveland. Dec. 8, AIME, Arizona Section, all-day meeting, Tucson. Jan. 6, 1953, Society for Applied Spectroscopy, Socony-Vacuum Training Center, New- York City. Jan. 14, 1953, AIME Connecticut Section, Hammond Metallurgical Laboratory, Yale University, New Haven, Conn. Jan. 14-16, 19th Annual Meeting of Society of Photogrammetry, Shoreham Hotel, Washington, D. C.

Jan 1, 1952