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By Persifor Frazer

The subject of Egypt, to use the words of perhaps the second of modern writers on the subject [Deodat. de Dolomieu, in Observations sur la Physique, etc., January, 1793, vol. xlii., pp. 41+, 108+; Abbe Rozier, J. A. Mongez, and J. C. Delametherie, Paris], is one which strongly excites our interest, and everything relating to it demands our respect. "Thus," he continues, "the Greeks appeared to the Romans," ..." thus Egypt appeared to the Greeks, and thus all three appear to us." This writer, in the three parts of the memoire given above, speaks of Norden as the modern pioneer of Egypt, and does not seem to have made original observations himself; nevertheless he seems to have rendered the same service to his authority that Playfair not very long afterward rendered Hutton. The limitations of a paper will permit little else than citations, but these are so numerous that, unless much compressed, they would supply a chapter of moderate size. A great deal of the very interesting memoire of Dolomieu is taken up with Quixotic tilts

Jan 1, 1883

By W. Crafts, J. L. Lamont

Electrolytic extraction of carbides from quenched and tempered steel and their examination under the electron microscope were found to be helpful in understanding the mechanism of secondary hardening in alloy steels1 and the same technique has been applied to isothermally transformed steels. A preliminary survey of the utility of the method has indicated that it has promising possibilities for investigating the characteristics of pearlite and bainite. The examination of a few carbon and chromium steels has suggested that pearlite is formed with carbides of two varieties representing the lamellar and nonlamellar forms and that bainite appears to form with a structure analogous to, but significantly different from, martensite. Procedure The method used for examining the carbides was similar to that described previously.1 The chromium steels used in the investigation were made from an Armco iron base in an induction furnace and were not treated with grain-refining deoxidizers. The composition of the steels is given in Table 1. Three-inch square ingots were forged and rolled to 1/8-in. thick sheet for use in the isothermal studies. After rolling, the sheets were sandblasted to remove the rolling scale. Specimens approximately 3/4-in. wide and l1/2-in. long were prepared from the 1/8-in. sheet. They were heated in a salt "bath at 2100°F (1150°C) for 1/2 hour, transferred to other salt baths at 1300°F (704°C), 1000°F (538°C), 800°F (426°C), or 600°F (315°C), held for various periods up to 100 hr and finally quenched in water. After quenching, the specimens were cut in half, one half being submitted to microscopic examination and the other half being used for the electrolytic extraction. The isothermally transformed specimens were submitted to examination under the light microscope to determine the degree of transformation and type of structure and were photographed at 2000 X. Carbide residues were obtained by electrolyzing in 10 pet hydrochloric acid and collecting the residue in glycerine to minimize attack by the acid. As pointed out in the earlier paper, the carbides are attacked to some degree during electrolysis. This attack is relatively minor on the coarser carbides but may be quite severe on the fine bainitic carbides. The residues were washed free of the glycerine with water and alcohol. The alcohol was removed by repeated washings of amyl acetate, and the amyl acetate suspensions were transferred to stoppered vials. Debye-Sherrer X ray diffraction patterns of the residues were prepared using a chromium target. A selection based on the microstructure and X ray data was then made of samples considered most illustrative of the progress of transformation. Electrolytically extracted residues from these samples were submitted to examination by W. D. Forgeng and A. C. Jenkins on the electron microscope at the Research Laboratories of The Linde Air Products Co. and electron micrographs were made at X 5000 and enlarged to 25,000 X. The micrographs obtained with both the light and the electron microscopes are mounted side by side in the accompanying figures. Although no effort was made to establish the T-T-T diagram for the chromium steels, the times for holding in the salt bath were adjusted with the intention of making the samples represent different stages in the transformation at temperatures of 600, 800, 1000, and 1300°F. The degrees of transformation and results of X ray examination are shown in Tables 2—4. The carbide designations refer to orthorhombic or trigonal carbide types and are not meant to imply that the compositions are exactly as indicated. X ray Diffraction Data The occurrence of Fe3C and Cr7C3 in these steels was found to be consistent with published data on comparable chromium steels. Steels A and B with relatively low ratios of carbon to chromium contained Cr7C3 in the pearlitic structures and FeuC in the

Jan 1, 1950

By L. R. Bottomer, G. M. Leary

"The Copper Canyon property is located in the Galore Creek area of northwestern British Columbia. Porphyry copper-gold mineralization on the property is notable for its high gold content and close spatial relationship with a distinctive suite of high level syenitic and monzonitic intrusions, and pseudoleucite-bearing volcanic country rocks. The style of alteration and mineralization is similar in many respects to the nearby Galore Creek deposits.The current geological resource of 32.4 million tonnes grading 0.75% Cu, 1.17 g/ t Au and 17.1 g/t Ag is insufficient to support a mining operation, but definition of additional reserves combined with improved transportation infrastructure in the region may change this in the future. The climate, topography and proximity to an active glacier indicate that the most likely production scenario is an underground bulk mining operation, with the ore being milled offsite.IntroductionThe property is located at 57°07' North latitude, 131 °21' West longitude, on NTS sheet 104G/ 3W, approximately 160 km northwest of Stewart and 90 km south of Telegraph Creek (Fig. 1). The Galore Creek camp and airstrip are located 6 km to the west. Current access to the property is via helicopter either from Galore Creek, or from the Bronson Creek airstrip 32 km to the south-southeast.The deposit occurs within the Boundary Ranges of the Coast Mountains, on the north side of the east fork of Galore Creek, which flows northerly into the Scud River and thence westerly to the Stikine River.Topography is rugged. In the deposit area, elevations range from 1130 m to 1750 m. Valley glaciers and permanent snow and ice fields are characteristic of the region at these elevations, and at its southern limit, mineralization is truncated by the East Fork Glacier.The property is entirely above the treeline, and except for areas of moraine cover and talus slopes, outcrop is abundant."

Jan 1, 1995

By Nicol S. K, Firth B. A

Much effort over the years has been put into the task of devising parameters which adequately assess the metallurgical efficiency of mineral processmg operations. One of the most celebrated of these methods is the so-called "release analysis" method of Dell (1953) which tackles the problem in terms of an ideal separation based on sequential retreatment of the products and tails of a given separation process. Other methods have also been proposed by Jowett (1969) and by Holland-Batt (1971 ). While these procedures are appropriate to multi-component mineralogical separations, they perhaps do not lend themselves to the much more simple two-component systems encountered in coal preparation. However Dell (1962) has suggested the use of the term "specific profit" in coal preparation in order to assess the conditions that give maximum economic gain. Specific profit is derived from data relating washability data with equipment performance and operating costs. The procedure for using this criterion for comparative purposes is therefore somewhat cumbersome as is illustrated by its lack of widespread acceptance in the coal preparation literature.In contrast, an efficiency index, E, which is both simple and meaningful from the utilitarian standpoint, has been proposed by Tsiperovich and Evtushenko (1959a). This index is defined by the relation, E = Yield X Tailings ash/Product ash (1) A cursory examination of this parameter shows that it increases when yield and tailings ash increase and also when product ash decreases; all of which are desirable circumstances in coal cleaning operations.Further, it will be shown that slight variations in operation are amplified by this function which makes comparisons simple and direct.While the use of this index is quite extensive in the Soviet coal preparation literature for some reason it has not received wide usag~ elsewhere.

Jan 1, 1978

By Clyde L. Brown

The ignition source of fires and explosions in coal mines is sometimes difficult to explain because resulting widespread destruction often erases valuable evidence that might reveal the cause. However, through years of experience, investigators have been able to piece together enough evidence to establish the reasons and, thereby, have been equipped to recommend corrective or preventative measures. The pattern of hazards is not constant. It changes with the development of new practices and new equipment. Important among the new hazards to coal mining are those introduced by electricity. In addition to the dangers of electric shock, fires and explosions from heat and arcs, and premature blasts, certain others have developed as a result of stray electric currents from direct-current traction systems. The conventional direct-current power-distribution system in coal mines is conducive to electrolysis damage to mine tracks, metallic pipelines, grounded power conductors, and structures in a position to become conductors of stray currents. The voltage drop resulting from power demand on intentionally grounded power conductors and accidental grounds on insulated conductors are common sources of stray currents in coal mines. Uncontrolled electric cur-rents flowing through the earth and metallic structures can be a menace, and these contribute to the estimated $6,000,000,000 annual loss caused by corrosion. The purpose of this publication is to discuss some of the electrolysis hazards in the coal-mining industry and to outline corrective measures to alleviate them.

Jan 1, 1962

Waitemata Tectonic Event(25 Ma ago) created a subduction system from the northeast of Northland, causing: (1) the emplacement of the Northland Allochthon (24-23 Ma) which provided argillaceous limestone and serpentine to Northland, and minor copper to both there and East Cape (located off Northland then); and (2) Northland volcanism (from 22 Ma), which lacked economic mineralisation. The Kiwitahi Tectonic Event (1714 Ma) caused: (1) a realignment of volcanism - from coastal western Northland, to west of the Hauraki Plains (Kiwitahi); (2) a start to the migration southwards from Northland of (a) the Alpine Fault System towards Marlborough today, (b) subduction towards Cook Strait, and (c) volcanism towards Taranaki-to-Bay of Plenty (initially through Coromandel, Kiwitahi, and offshore west coast); and (3) a start to rhyolitic volcanism & associated hydrothermal activity. The latter caused epithermal mineralisation, providing in Coromandel the best known North Island metalliferous deposits. Andesitic volcanism has been active in both of these two contrasting, subequal belts since 22 Ma. Rhyolitic volcanism and hydrothermal activity was wholly restricted to the eastern Marshall Belt, with an abrupt limit to economic mineralisation at the Volcanic Divide (within Hauraki Plains) and a major change there to basaltic volcanism of the western Searle Belt. The Kaimai Tectonic Event (5-1.5 Ma) caused: (1) a temporary reversal in volcanic migration in the Searle Belt, and a duplication of rhyolitic & hydrothermal activity at Waihi (Marshall Belt); (2) the rotational rifting of both the Central Volcanic Region (by 30¦) and the Hauraki Rift (10¦), causing major curvature of the North Island and New Zealand, and the transfer of the offshore subduction system from Coromandel to East Coast; and (3) an effective end to Coromandel mineralisation. Post-Kaimai Volcanism (1.5-0 Ma) included: (1) andesitic volcanism in the Searle Belt, yielding the western coastal titanomagnetite deposits; and (2) andesitic, and rhyolitic & hydrothermal activity in the Marshall Belt - the latter providing geothermal energy, sulphur, and pumice/perlite deposits. Post-Subduction (Intraplate) Volcanism (10-0 Ma) developed in a steadily expanding northwest region of relative tectonic quiescence, as subduction and its volcanism migrated southwards. Intraplate volcanism was predominantly basaltic, providing excellent aggregate; but less common rhyolitic & hydrothermal activity provided geothermal potential and mercury at Ngawha and at Puhipuhi, and halloysitic clays of extreme brightness elsewhere in Northland. This volcanism has reached as far SE as Mayor Island, providing an early New Zealand mineral resource - obsidian.

Jan 1, 1997

The National Institute for Occupational Safety and Health (NIOSH) conducratory and field tests to evaluate the effectiveness of dust collector bags for reducing dust liberation and operator exposure from a roof bolter?s dust collection system. The laboratory tests evaluated the bag?s effectiveness to contain dust and the effect on canister filter loading in both a bag and bagless condition. The dust emissions from the collector?s exhaust were also measured in each condition during laboratory testing and show that nearly 100% of the test dust fed into the collector was captured by the dust bags. Loading and pressure drop on the dust collector?s canister filter is greatly decreased when using the bags, enabling longer periods of drilling without filter removal/cleaning. The field results showed that, even though dust standards were met, respirable dust in exhausted emissions was reduced around the bolter. Laboratory and field results show that benefits from use of the bags are realized in all areas of operator exposure.

Jan 1, 2008

By T. W. Beck

The National Institute for Occupational Safety and Health (NIOSH) conducratory and field tests to evaluate the effectiveness of dust collector bags for reducing dust liberation and operator exposure from a roof bolter’s dust collection system. The laboratory tests evaluated the bag’s effectiveness to contain dust and the effect on canister filter loading in both a bag and bagless condition. The dust emissions from the collector’s exhaust were also measured in each condition during laboratory testing and show that nearly 100% of the test dust fed into the collector was captured by the dust bags. Loading and pressure drop on the dust collector’s canister filter is greatly decreased when using the bags, enabling longer periods of drilling without filter removal/cleaning. The field results showed that, even though dust standards were met, respirable dust in exhausted emissions was reduced around the bolter. Laboratory and field results show that benefits from use of the bags are realized in all areas of operator exposure.

By Adam K. Smith

Over-exposure to noise remains a widespread, serious health hazard in the U.S. mining industry despite 25 years of regulation. Most other categories of illnesses and injuries associated with mining have improved, with the exception of hearing loss. In order to reduce cases of Noise Induced Hearing Loss (NIHL) in the mining industry, retrofit acoustic treatments and controls are being developed to subdue noise at the source. The Mine Safety and Health Administration (MSHA) coal noise sample data collected from 2000 to 2005 has determined that continuous mining machines rank first among all mining equipment whose operators exceed 100% noise dosage. The continuous mining machine conveyor, used to move coal from the cutting face to the rear of the machine, has been identified as a dominant noise source. A dual sprocket conveyor chain was tested as a potential solution. Sound power level measurements conducted at the Pittsburgh Research Laboratory (PRL) accredited reverberation chamber showed a 3 dB reduction in the A-weighted sound power level when the dual sprocket chain was implemented. Underground results show an 8-hour Time Weighted Average (TWA8 hrs) reduction a 3 dB for continuous mining machine operators. Utilizing this newly developed noise control, along with previously proven controls, provides continuous mining machine operators an opportunity to be within the MSHA-Permissible Exposure Limit (MSHA-PEL).

Jan 1, 2009

By Frank S. Hurley

To comply with the California Mine Safety Orders pertaining to transportation of mine workers over mine railroads, the management of the New Idria mine in San Benito County, Calif., designed special man-cars. The new regulations, dated October 1958, make it mandatory for mine man-cars to be designed for carrying five or more men to and from the mine workings. At the New Idria mine, largest single producer of mercury in the U.S., each shift normally employs about 70 men. However, with the possibility of a future increase in the work force, seven man-cars were constructed with a total carrying capacity of 84 men. The general design of the mine man-cars was dictated by safety regulations plus the physical characteristics of the mine-low headroom, limited side clearance in haulageways, and track irregularities due to ground swells. The cars measure 10 ft long, 44 in. wide, and 50 in. high and were built at an average cost of $450 per car. All assembly work was done at the mine site.

Jan 7, 1960

By B. Sivarama Sarma, Biswabikash Rout

"Seepage control has to be achieved with plastic concrete cut-off diaphragm walls in dam structures. Materials selected for construction of cut-off walls must be durable, impermeable and have stiffness comparable to the surrounding soil.Plastic concrete provides a feasible and economical solution for construction of durable and impermeable cut off walls for dam structures. Plastic concrete wall should not be understood as a concrete wall with similar mechanical properties of concrete used in buildings, piles and spillways sections. Though it consists of the same materials as those of conventional concrete it has the major differences in end product due to predominant addition of bentonite slurry in the mix with very high water cement ratio. This makes the hardened concrete with very low compressive strength less than 5MPa and high failure deformations after the peak load.This technical paper examines a case study, the typical specifications on demand for construction and the issues corresponding to misunderstanding of the material as a structural grade concrete material. Conclusions were drawn based on a few project site quality data and trial mix experimental data. The anomalies in specifications on demand for construction of curtain wall in a dam structure were removed with modifications.INTRODUCTIONDiaphragm walls which are constructed in trenches made of plastic concrete basically serve the function of seepage control under confined measures. They should have the ability to sustain and undergo large plastic strains as compared to conventional concrete. The three basic mechanical properties of plastic concrete cut-off walls are to have least permeability, minimum strength to retain its shape and ability to undergo large deformations under confined loading conditions. The constituents of plastic concrete are cement, bentonite, coarse and fine aggregates, chemical additives to improve flow of concrete and sometimes to retard the setting time and water."

Jan 1, 2017

By Lon Santis, David Buckwalter, Ken Steinmetz

This paper describes a magazine security system using two readily available cellular telephone-based technologies. The system is comprised of vibration sensors and remote cameras. The system is used at a Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) licensed explosives storage location in Pennsylvania to comply with PA Department of Environmental Protection (PADEP) regulations. The system provides instant notification to the licensee via cellular modems, text messaging, phone call, and e-mail. Likewise, the licensee can control the system remotely over the internet and using text messaging commands. The vibration sensors attach to the door of the metal type I magazines magnetically and detect any movement or vibration. The cameras trigger on movement and thermal radiation changes and can also be triggered manually to check alarms received from the vibration sensors. The previous system was comprised of a base unit and magnetic strips. The magnetic strips were powered by a hard line from the control unit and mounted on the doors and top of magazine creating a bond, that when broken triggered an alarm. Our main issues with the unit were the delay in alert times and tech support. Because of these issues, we decided an upgrade was necessary. Compared to that previous system used at this site, these new systems are highly affordable, carefree and reliable.

Jan 1, 2014

By Gerald V. Jergensen

Does an idea have merit? What does it cost to implement? Can the concept be implemented successfully? The ultimate proof is to try, then see. However, when there are many millions of dollars at stake, blindly building and trying requires considerable courage. Owners and investors in retrospect might choose other less complimentary words. So we might ask, "How might we establish the feasibility of an idea or concept before committing large sums of money to the ultimate test?" From this basic and prudent question, has evolved the engineering concept of the feasibility study. A feasibility study is simply a systematic evaluation of an idea or concept to determine the prospects for success. In a literal sense, a feasibility study considers an idea in terms of its data base, "builds" the idea on paper, "operates" that idea, calculates the cost and benefits, then measures the probable success in terms of some economic, technical or financial standard. Feasibility studies can be quite modest in scope yet provide useful insights as to the viability of an idea. A study might be initiated only to examine the completeness or validity of the metallurgical data base. Another study could be a search for a workable idea or solution to an already-identified possibly troublesome problem. In this latter case, the question, "Will it work?" may be far more important than, "How much will it cost?" Feasibility studies are sometimes global in scope, involving several dozens of specialists and examining an entire "grass roots" mining complex. Other studies may be less ambitious but equally important in examining an expansion proposal or developing new operating techniques. Studies may be commissioned to remove plant bottle-necks, solve maintenance problems and so on. The terms study and feasibility study are used interchangeably in this chapter. They denote a systematic method to examine a proposed concept or idea. DATA BASE Typically, studies are initiated with a minimum amount of specific information and a maximum number of assumptions. As the work proceeds and the data base expands, assumptions are replaced

Jan 1, 1982

Whilst decisions to commit projects have traditionally been heavily influenced by hurdle rates for d.c.f. analysis, it is suggested that evaluation of competitors' costs may be a desirable additional tool.The MICAS system developed over the past four years is described. This computer system uses standard costs modified by District and Mine factors to allow estimation of individual mine costs. The data base contains more than 15,000 items of data and more than 6000 costs are calculated.Recent applications include use for competitive analysis, predictive analysis, statistical analysis, and comparative assessments with scopes ranging from a few mines to the whole Australian export industry. Some areas where care is necessary are outlined and potential further uses are discussed.

Jan 1, 1985

By Al Gagnon

Since start-up in 1972, many circuit problems have been encountered, most of which were related to the abundance of fines (-28 mesh), which the circuit had not been designed to treat. The major problems associated with the original circuit included excessive loss of magnetite, reduced throughput during periods of a high proportion of fine coal in the plant feed and low yield in the fine coal circuit. This paper outlines the coal processing circuit at Fording Coal Limited as it exists today, with emphasis on the changes to the original fine coal treatment circuit.

Jan 1, 1978

By Mason D. O, Tuckwell K. D

Whole rock geodhemical analyses from samples of Potosi gneiss within the Willyama Supergroup have been utilised to identify geochemical trends towards Pb/Zn ore positions. Although the analyses come from disparate sources they have been incorporated in the data base only if locational, sampling, analytical, lithological and stratigraphic descriptors were reliable. These data have been statistically analysed using programmes of the GASP software package. A discriminant function has been derived which permits Potosi gneiss associated with the Pb/Zn lode horizons in the Broken Hill domain to be distinguished from Potosi gneiss in a similar stratigraphic position in the Maybell Domain. In the "near ore" position the Potosi gneiss has significantly lower mean Na2O and significantly higher mean MnO. Also mean Rb, CaO and K20 are higher and mean Sr lower. This discriminant function serves to identify areas prospective for Pb/Zn mineralisation. A second discriminant function based on MnO, Si02 and K20/Na20 gives a semi- quantitative indication of proximity to ore.

Jan 1, 1983

By Keith G. Wallace, K. M. (Chris) Chmura, Kirk H. McDaniel

The Waste Isolation Pilot Plant (WIPP) performed a feasibility analysis for the purpose of either modifying, supplementing, or replacing its two main mine fans. The WIPP, located near Carlsbad, New Mexico, is a U.S. Department of Energy (DOE) fa¬cility designed to demonstrate the permanent, safe disposal of U.S. defense-generated transuranic waste in a deep bedded salt deposit. Since the centrifugal fans were installed in 1988, multiple op¬erational and performance concerns have been identified. A com¬prehensive engineering study was conducted in 1995 to: 1) Qualify and quantify operational concerns, 2) Evaluate possible alternatives, and 3) Recommend an optimum solution. Multiple system modification and/or replacement scenarios were evaluated with associated cost estimates developed. The study considered replacement with either centrifugal or axial fans. Multiple fan duties are required at the WIPP. Therefore, Variable Frequency Drives and Inlet Vane Controls (IVC) were investigated for centrifugal fans. In-flight adjustable blades were investigated for axial fans. The study indicated that replacing the existing system with two double-width, double-inlet centrifugal fans equipped with IVCs was the best choice. This alternative provided the most desirable combination of: 1) ensuring the required operational readiness, and 2) improving system performance. The WIPP is currently planning to replace the first fan in 1997.

Jan 1, 1997

By H. Fukuyama

The wetting behavior of single crystalline MgO by fayalite-type slag melts has been studied by the sessile drop technique incorporated with high temperature X-ray radiography. The experiments were performed under oxygen partial pressures of 10-6 and 10-4 Pa at 1473 K. Mass ratios of iron to silica, Fe/Si~, in the slag employed were 1.4 and 2.0. To investigate the interfacial reaction, experiments using high density MgO crucibles were also conducted. The reactions at the interfaces were examined by Electron Probe Microanalysis. The contact angles between the slag melts and the MgO substrates were found to be relatively low, ranging from 30 to 10 degrees. The surface tension of the slag was 0.4 N/m for a slag of Fe/Si02 = 2.0. Two phases, magnesiowiistite and olivine, were observed at the interface. Interdiffusivity in magnesiowiistite solid solution was determined as a function of iron oxide content. Phase relations between magnesiowilstite and olivine, and the growth rates of both phases, are also discussed

Jan 1, 1996

By D. G. Westlake

NUMEROUS hydride habit planes in zirconium, Zircaloy-2, and Zircaloy-4 have been observed by various researchers and have been compiled by Louthan and Angerman.1 While only partial agreement exists on the identification of these habit planes, there is a growing consensus that a tensile stress applied on a polycrystalline rod during slow cooling will cause the hydride platelets to lie perpendicular to the tensile axis. walters2 agrees with Louthan and Angerman who reason that "The particular plane on which precipitation will occur is the plane that will result in the maximum relief of stress by precipitation of the low-density hydride." The experiment described below was initiated to test this hypothesis on a single crystal of zirconium. A single-crystalline tensile specimen of zone-refined zirconium, designated number 13 in a previous study,3 had a square cross section with one pair of parallel faces only 4 deg from the basal plane of the hcp structure. The tensile axis was about 86 deg from the (0001) pole, 14 deg from the (1010) pole, and 16 deg from the (1150) pole. The specimen was charged to 50 ppm H by allowing reaction with the correct amount of hydrogen at 1073°K, homogenizing at this temperature for 2 hr, and cooling in the furnace. Two- surface analysis revealed that hydride platelets had precipitated parallel to the three {1010} prism planes. The specimen was heated to 673°K, in air, for 16 hr to bring the hydrogen back into solid solution, and furnace-cooled to 573°K.* It was then stressed in ten- sion at 1.2 kg per sq mm. (This produced a resolved shear stress of 0.6 kg per sq mm for glide on the prism plane with the highest Schmid factor. A higher stress would have produced significant strain at this temperature because the critical resolved shear stress for prism-plane glide in this crystal was only 1.0 kg per sq mm at ambient temperature.) The poles of the three prism planes were at angles of 14, 46, and 74 deg to the tensile axis so that an applied stress would exert normal stresses on the three planes in the approximate ratios 10:5:1, respectively. As soon as the stress was applied, the sample was furnace-cooled to room temperature. It was ground on wet Sic paper and chemically polished in 50 parts HNO3, 50 parts water, and 7 parts HF before examination. The result of the experiment was negative; i.e., the three (1010) planes were of equal importance as hydride habit planes.* It must be admitted that the ex- periment is not entirely comparable to those performed by walters,2 Louthan,5 and Louthan and Marshall6 on polycrystalline materials. They have found that some critical stress (below the macroscopic yield stress) is required for stress-orienting the hydrides. The applied stress in the present experiment was, by necessity, smaller by an order of magnitude than the critical stresses they report for the various materials. If the critical stress was related to the microstructure, one might postulate that it should be decreased by increasing the degree of perfection of the metal lattice and by increasing the grain size. But the experiment above suggests that, for the extreme case of a zone-refined single crystal of zirconium, the critical stress lies above that which one can apply without introducing gross plastic strain as another variable.

Jan 1, 1967

By Eckley B. Coxe

I wish to call the attention of the Institute to a peculiar variety of anthracite which occurs in the Buck Mountain vein at our collieries at Drifton, and in the same and other veins in different localities in the anthracite coal-fields. It is known among the workmen as iron-gray or cast-iron. It has a dull, greasy appearance, as if a piece of ordinary anthracite had been rubbed with a dirty and greasy rag and allowed to dry. It was formerly considered a very impure coal containing a high percentage of ash, and was picked out of the coal and thrown away. But the following analysis of it and of its ash, made by Mr. J. Blodget Britton, of Philadelphia, shows that such is not the case, the percentage of ash not being much higher than that of the ordinary anthracites as they are prepared for market. ANALYSIS OF COAL. Water,.........4.36 Fixed carbon, by difference,.. 84.90 Volatile combustible matter,. . 3 48 Ash,..........7.26 100.00 The carbon proved to some extent to be of the nature of graphite, and slowly combustible. ANALYSIS OF ASH. Silica,.........25.66 Sulphur,........ .17 Alumina,........27.03 Phosphoric acid,.......21 Ferric oxide,.......42.83 Alkali, undetermined matter and Lime,.........1.56 loss,.........60 Magnesia,........1.83 Manganous oxide,......11 100.00 We recently collected a quantity of the substance and made a fire with it, in an ordinary stove, which was kept up several days. We found that it burned with intense heat, and apparently as freely as our other coal does. Mr. Britton is probably right in his view, that the difference in appearance is not due to impurities in the coal, but to the fact that the carbon is in a more or less graphitic form, as many of the standard coals are no purer. I bring this before the Institute as I know that a large quantity of this valuable fuel is thrown away every year, on account of its supposed impurities.

Jan 1, 1879