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By Warden A. Moller

(Pittsburg Meeting, March, 1910.) THE Fushun coal-field, now being opened up by the South Manchurian Railway Co., is connected with the main line by a branch, 30 miles long, from Sui Chia Tun, 10 miles south of Mukden, the capital of Manchuria. The coal-field, which lies on the southern bank of the Hun river, 25 miles east of Mukden, consists of a long narrow valley,. running east and west between hills composed of granitic and volcanic rocks. At the foot of the northern hills, the Hun river flows westward towards the Liao river, which drains the greater part of South Manchuria. At the foot of the southern hills, resting immediately upon volcanic rocks, and overlain by 20 ft. of alluvial, is a thick layer of Tertiary shales, carrying near the base two coal-seams. In many places the lower of these two seams is in immediate contact with volcanic lauds and basalts, the flows of which were evidently both prior and subsequent to the formation of the coal-seams. This contact has practically destroyed the lower seam for commercial purposes. The value of the field lies in the upper seam, which, for a length of nearly 8 miles, varies from 100 to 130 ft. thick. Of this seam, 85 per cent is good coal. The seam dips to the north conformably with the shales, at angles of from 25° to 30°, and appears to have an uninterrupted dip for about 1.5 miles before being possibly cut o$' by the northern hills. The coal-bearing shales extend east and west for a length of about 20 miles, but towards the east the continuity of the seams is broken by intrusive rocks. The coal is of the sub-bituminous variety, low in ash, bright in appearance, and breaks with a conchoidal fracture. It has the usual qualities of Tertiary coal-quick steam-raising and poor stacking-qualities. Pieces of resin, varying in size from

Apr 1, 1910

Discussion of the paper of H! M. CHANCE, presented at the Pittsburgh meeting, October, 1914, and printed in Bulletin No. 91, July, 1914, pp. 1461 to 1466. R. V. Norris, Wilkes-Barre, Pa.-In his resume of coal-taxation methods Mr. Chance has apparently confined his investigation to bituminous coal, so a summary of the anthracite situation as to coal assessment should be of interest. The anthracite region of Pennsylvania in its 484 square miles of measures lies in the counties of Wayne, Lackawanna, Luzerne, Carbon, Schuylkill, Northumberland, and Dauphin, and in each of these different methods of assessment have been adopted. The assessments for taxation in Pennsylvania are made under Acts of the Legislatures of 1841 and 1842, under which the assessors are re¬quired to "assess rate and value every subject of taxation according to the actual value thereof, and at such rates and prices as the same would bring at a bona fide sale after due notice." Under this general law coal land has been assessed as such, but up to about 25 years ago the coal was assessed at rates so low as to be unimportant, though the rates in each township and municipality, even in the same county, showed no agreement or ascertainable basis. In the late '80s, the need for greater revenue drew attention to the possibilities of collecting much larger taxes from the coal lands and, spurred by public demand, the assessing authorities in some counties undertook a reassessment of coal. The method pursued was to demand from each owner a statement of the area and average remaining thickness of coal on his lands. On this return, made in some cases under oath, an assessment based on foot-acreage was levied, with a resulting great increase in valuation, but the valuation per foot-acre was low and no serious objection was made. This assessment with occasional increases of rate remained in force until 1907, when, in the triennial assessment of that year, a complete revision of the valuation was again attempted, engineers were employed by the counties to check the accuracy of the returns from the owners, and, based on the foot-acreage thus obtained, an enormous increase, to $65 per foot-acre, was made in the valuation. This assessment was resisted in the courts by appeals resulting in very extensive litigation, and a final determination of the validity of the 1907 and all subsequent assessments has not yet been obtained. In the first appeals tried the rate calculated on a foot-acre valuation was reduced by the Luzerne County court to about $45, while the. Lackawanna County courts reduced a larger rate to $67. The county authorities were, how-

Jan 4, 1915

By W. R. Toeplitz

H. N. Ghenn.*—It has been established that the accuracy obtainable from any precision machine is a function of the wear resistance, maintenance and closeness of fit of the bearings, hence I would like to ask Mr. Toeplitz how these oil-less bearings compare with cast iron or babbitt or similar materials when used on precision machinery. Could these bearings be used, for example, on a grinding machine in which work must be held to a tolerance of plus or minus 0.000025 inch? W. R. TOEPLITZ.—The metal-powder bearings can be held to very close tolerances and are used in place of cast iron and babbitt on precision machinery.

Jan 1, 1945

By G. S. Hume

Activity in geological exploration and drilling continued in Canada in 1945 at about the same rate as in the previous year, but with disappointing results as far as new production is .concerned. Both in the foothills and on the Plains of Alberta, however, there are wildcat wells that have either given encouraging shows or some production, which are very important in relation to future developments. The normal decline of Turner Valley, the largest producing field in Canada, has continued, and this decrease has not been offset by new discoveries. In addition, the closing of the Canol pipe line on March 31, 1945, isolated the Norman Wells field in the Mackenzie River valley, and the outlet at present. is confined to supplying the relatively small local requirements. This

Jan 1, 1946

By C. Richard Tinsley

Like most minerals, coal is inherently a demand-limited commodity. The very sedimentary nature of its occurrence implies greater availability potential than demand. But this situation is overridden by economics among fuels, between coals, and within coal blends. Such considerations make coal forecasting a very hazardous profession indeed. THERMAL COAL If one thought that the lead times involved with a mining project were very long, one has obviously not been exposed to the planning process in the electric generation business - a process seriously confounded by shifts in load growth, environmental pressures, capital intensity, security of fuel sourcing, inter-fuel economics, and so on. But as a general rule, the near-term forecasts for thermal coal can reliably be based on a bottom-up, plant-by-plant analysis. Cement plant conversions can also be reasonably estimated next in order of reliability, although they have a much wider spectrum of coal qualities and fuel sources to choose from with a notably higher tolerance for sulfur and ash. Finally, industrial demand can be assembled from the estimates for conversions by pulp/paper plants, chemical plants, etc. The industrial sector is harder to estimate, since it may involve small boilers or dual-fired units. Assessing demand in the Pacific Rim is relatively a straightforward process in the near term because the major importing countries are all located on the Asian continent with either negligible or very minor (yet stable) indigenous coal production, (itself often operated on a subsidized basis). Furthermore, all imports are seaborne. These major importers are Japan, Korea, Taiwan, and Hong Kong with Thailand, Singapore, and Malaysia up-and-coming consumers. The suppliers to this market all have substantial reserves to back up decades of exports to these countries. Australia, the US, Canada, South Africa, China, and the USSR dominate the supply side. The second oil-shock of 1979/1980 has convinced the importers that reliance on oil can be expensive and eminently interruptible. Thus, they are determined to diversify away from oil' to nuclear and coal for generating electricity and for coal for other purposes where possible. This trend is seen to continue even in the face of the oil glut worldwide and oil-price reductions in early 1982. But the importers are also convinced that reliance on one coal source and, in particular, one infrastructure route for the coal chain from mine to consumer can be equally expensive and interruptible. Strikes in the US and Australia; excessive demurrage at certain ports; relegation of coal to a lower priority on multiple-use railroads in the USSR and China; and concern over escalation on high-infrastructure or high-freight coal chains are among the risks worrying the importers. As a consequence, Pacific Rim thermal coal purchases are being allocated among supplier nations, between ports, and within each country. An example of Japan's shift away from Australia and toward the US and Canada is shown in the estimates in Table 1. But the confidence of the import estimates deteriorates sharply beyond the plant conversion timetables and construction schedules in the near term. If part of the second generation of coal-fired power plants can handle lower-energy coals, the field of suppliers could widen to accept sizeable tonnages from Alaska, Wyoming, Alberta, or New Zealand resources. These supply sources generally have some infrastructure or freight advantage to compensate for their lower quality and to compete on a delivered energy-unit basis. These also offer diversification in sourcing. And the possibility of coal liquefaction in Japan further widens the sourcing network. A great number of Pacific Rim coal forecasts have been generated, especially for Japanese thermal-coal imports which are expected to grow strongly in the 1980's. Since the Japanese themselves have not yet settled their energy policy, the exact numbers are hard to call. Nevertheless, at 50 million tonnes of imports in 1990, Japan would consume 50-60% of the total Asian thermal coal imports as shown on Tables 2 and 6. The next most important consumers are the "island" nations of Korea, Taiwan, and Hong Kong (see Tables 3-5). All three are embarking on power plant developments usually with captive unloading facilities, capable of accepting more than 100,000-dwt vessels. Korea, with no-indigenous bituminous coal, is not especially enamoured with US coals, which are deemed too heavily loaded by freight and infrastructure costs -- up to 70% of the delivered price. Thermal coal contracts are presently split to Australia (70%) and to Canada (30%). Korea Electric Power Co. is already considering second-generation boilers capable of burning lower-quality coals than the present standard. Korea does burn domestic anthracite.

Jan 1, 1982

By Sir James Kitson

By the courtesy of the President and Council of the American Institute of Mining Engineers, I have been invited to take the chair and open the proceedings of this congress. It is a graceful compliment to those members of the Iron and Steel Institute who are your honored guests at this moment—an acknowledgment of high consid-

Jan 1, 1891

By Fred C. Bond

MOST investigators are aware of the present unsatisfactory state of information concerning the fundamentals of crushing and grinding. Considerable scattered empirical data exist, which are useful for predicting machine performance and give, acceptable accuracy when the installations and materials compared are quite similar. However, there is no widely accepted unifying principle or theory that can explain satisfactorily the actual energy input necessary in commercial installations, or can greatly extend the range of empirical comparisons. Two mutually contradictory theories have long existed' in the literature, the Rittinger and Kick. They were derived from different viewpoints and logically lead to different results. The Rittinger theory is the older and more widely accepted. In its first form, as stated by P. R. Rittinger, it postulates that the useful work done in crushing and grinding is directly proportional to the new surface area produced and hence inversely proportional to the product diameter. In its second form it has been amplified and enlarged to include .the concept of surface energy; in this form it was precisely stated by A. M. Gaudin2 as follows: "The efficiency of a comminution operation is the ratio of the surface energy produced to the kinetic energy expended. According to the theory in its second form, measurements of the surface areas of the feed and product and determinations of the surface energy per unit of new surface area produced give the useful work accomplished. Computations using the best values of surface energy obtainable indicate that perhaps, 99 pct of the work input in crushing and grinding is wasted. However, no method of comminution has yet been devised which results in a reasonably high mechanical efficiency under this definition. Laboratory tests have been reported' that support the theory in its first form by indicating that the new surface produced in. different grinds is proportional to the work input. However, most of these tests employ an unnatural feed consisting either of screened particles of one sieve size or a scalped feed which has had the fines removed. In these cases the proportion of work" done on. the finer product particles is greatly increased and distorted beyond that to be expected with a normal feed containing the natural fines. Tests on pure crystallized quartz are likely to be misleading since it does not follow the regular breakage pattern of most materials but is relatively harder to grind at the finer sizes, as will be shown later. This theory appears to be indefensible mathematically, since work is the product of force multiplied by distance, and the distance factor (particle deformation before breakage) is ignored. The Kick theory' is based primarily upon the stress-strain diagram of cubes under compression, or the deformation factor. It states that the work required is proportional to the reduction in volume of the particles concerned. Where F represents the diameter of the feed particles and P is the diameter of the product particles, the reduction ratio Rr is F/P, and according to Kick the work input required for reduction to different sizes is proportional to log Rr/log 2.5 The Kick theory is mathematically more tenable than the Rittinger when cubes under compression are considered, but it obviously fails to assign a sufficient proportion of the total work in. reduction to the production of fine particles. According to the Rittinger theory as demonstrated by the theoretical breakage of cubes the new surface produced, and consequently the useful work input, is proportional to Rr-1.5 If a given reduction takes place in two or more stages, the overall reduction ratio is the product of the Rr values for each stage, and the sum of the work accomplished in all stages is proportional to the sum of each Rr-1 value multiplied by the relative surface area before each reduction stage. It appears that neither the Rittinger theory, which is concerned only with surface, nor the Kick theory, which is concerned only with volume, can be completely correct. Crushing and grinding are concerned both with surface and volume; the absorption of evenly applied stresses is proportional to the volume concerned, but breakage starts with a crack tip, usually on the surface, and the concentration of stresses on the surface motivates the formation of the crack tips. The evaluation of grinding results in terms of surface tons per kw-hr, based upon screen analysis, involves an assumption of the surface area of the subsieve product, which may cause important errors. The'evaluation in terms of kw-hr per net ton of 200 mesh produced often leads to erroneous results when grinds of appreciably different fineness are compared, since the amount of -200 mesh material produced varies with the size distribution characteristics of the feed. This paper is concerned primarily with the development, proof, and application of a new Third Theory, which should eliminate the objections to the two old theories and serve as a practical unifying principle for comminution in all size ranges. Both of the old theories have been remarkably barren of practical results when applied to actual crushing and grinding installations. The need for a new satisfactory theory is more acute than those not directly concerned, with crushing and grinding calculations can realize. In developing a new theory it is first necessary to re-examine critically the assumptions underlying

Jan 1, 1952

By G. P. Tiwari

Recrystallization and grain growth in thoria dispersed nickel and nichrome were recently studied by Webster as a function of temperature and deformation. The unexpected part of these results was that specimens which had received heavier deformation developed greater resistance to recrystallization. Retardation of recrystallization was accompanied by the formation of voids around thoria dispersion. To explain these results, Webster suggested that the formation of void around the particles increased the effective size of thoria particles. This resulted in greater impediment to the grain-boundary migration and as a consequence the recrystallization of the matrix is retarded. In the present note an alternative and more probable explanation for the effect of voids on recrystallization is presented. The exact mechanism of void formation in thoria dispersed nickel or nichrome is not known. However, it is reasonably certain that it must be preceded by the stress concentration in the matrix around thoria dispersion during the deformation.'' The resulting stress concentration must be sufficient enough to supply the surface energy for the new surfaces created. Further, the decrease in the strain energy of the matrix surrounding the potential void nucleus must be larger than the surface energy of the newly created surface. The release of strain energy due to formation of crack results in a strain free cylinder of the material around the voids.13 If the void formation is not localized, at few points only (as is the case here), this process may lead to considerable amount of release of strain energy of the matrix. The pattern of recrystallization behavior of single phase homogeneous matrix as well as the matrix having a second phase dispersion is same except for the fact recovery and recrystallization are more clearly delineated.14 In general, the recrystallization temperature is lowered (i.e., recrystallization is easier) with increase in the amount of cold work. This is due to the increase in stored energy in the matrix with increasing amount of deformation. If somehow there is a relaxation of strain energy in the matrix, the recrystallization should become difficult because of the decrease in the amount of stored energy available for recrystallization. Since the formation of voids leads to a decrease in the strain energy of matrix, the recrystallization of the matrix would be inhibited due to the formation of voids during deformation prior to recrystallization. It has been observed by earlier workers15'16 that the presence of preexisting voids in a matrix retards the recrystallization. The essential issue here is how do the voids act to produce this effect. If the voids influence recrystallization only by blocking the grain boundary migration, then the effect should be maximum when they are present almost exclusively along grain boundary. These conditions are obtained during high temperature deformation. However, the voids produced due to creep along grain boundary are not able to prevent recrystallization17 suggesting that they are not effective in blocking grain boundary movement. Recently it was shown by Davies and Williams that the voids can act as sinks for vacancies." As a result the processes dependent on vacancy diffusion like recovery, recrystallization, dislocation climb, and so forth, will be hindered. This fact may be responsible for inhibition of recrystallization during subsequent deformation and annealing cycles. It is to be noted here that there is a large difference between the density of voids in creep experiments and the other experiments where retarding effect of voids on recrystallization is seen. The voids in former may number up to l04 to l05 per sq cm whereas in latter cases the voids density is typically around 1010 to 1013 per sq cm. It appears that the decrease in supply of vacancies in creep is insufficient to adversely affect the recrystallization due to low void population. The author is grateful to P. Das Gupta and S. P. Ray for helpful discussions. Author's Reply D. Webster Tiwari appears to have misunderstood the nature of grain boundary-particle interactions. Tiwari (quoting Cahn) states that second phase particles become more effective as they become smaller, therefore as the voids in TDNiC make the thoria particles effectively bigger their ability to resist grain boundary movement is impaired. This particle size argument was originally proposed in the form of an equation by Zener 20 years agol9 and is not necessarily valid as is discussed below. However, assuming it is valid, it predicts a greater boundary restraining effect by smaller particles simply because their combined cross sectional area is greater at a constant volume. If the number of particles remains the same and their effective size increases, as in the present case, Zener's equation predicts a greatly reduced grain size. This is because the effect

Jan 1, 1970

By E. J. ENGEL

The New York talc deposits of commercial importance are in St. Lawrence and Lewis counties, in the northwest Adirondack Mountains (Fig 1). All of the deposits are of pre-Cambrian age and occur within highly deformed and recrystallized marble of the Grenville series. The deposits in St. Lawrence County, near Gouverneur, are the largest and most productive of their type known in the Western Hemisphere. In 1948 the seven mines which are in operation will produce about 130,000 tons of ground talc. All talc production in Lewis County is from one mine. There the annual production ranges from 15,000 to 30,000 tons. These so called talcs of New York State include earth materials of differ- ent chemical and mineral compositions. In general the mineral talc is sub- ordinate in amount to other minerals in both the Gouverneur and Natural Bridge deposits.

Jan 1, 1949

By B. H. Caudle, A. B. Dyes, R. A. Erickson

The study of the influence of fluid mobilities on the sweepout pattern resulting from the injection of gas or water has been extended to cover the production period which follows breakthrough of the injected material. Mobility ratios over the range common in field operations (0.1 to 17) were studied for several pattern floods (five-spot, staggered, and direct line drive). The experimental data required for these studies were obtained by the use of the x-ray shadowgraph technique using miscible oil phases of different viscosities in porous plate mode1s of a reservoir element. From the shadowgraph pictures obtained before and after breakthrough of the injected fluid, flowing ratios at the producing well and cumulative volumes injected were calculated. The method for applying such data in predicting field behavior is illustrated for a water flood of a five-spot. For this case a range of mobility ratios of 0.5 to 5.0 results in: (I) nearly complete (95 to 100 per cent) sweepout pattern efficiencies at abandonment conditions, (2) production after breakthrough being responsible for as much as one-third of the total recovery at the lower mobility ratios, and (3) a twofold variation in the operating life of the reservoir. In determining the merits of a secondary recovery operation, the fraction of the reservoir which is ultimately to be swept by the injected fluid is of major importance. Because of its significance a large amount of research has been applied to the study of areal sweepout efficiency. Muskat, Wyckoff and Botset1,2 have presented the classic analysis of the pattern efficiency at breakthrough for several injection patterns in which the mobility of the fluids ahead of the injected phase front was equal to the mobility of the fluids behind the front. Aronofsky3 as extended this analysis of recovery at breakthrough through numerical computations and by the stepwise use of the potentiometric model to include the effect of different fluid mobilities ahead of and behind the invasion front on the line drive performance. Fay and Prats' have also employed numerical computations to show the influence of one other condition of fluid mobilities on the five spot flood. In a previous paper' a new method of attack on this problem which employed x-ray and porous plates was described. At that time experimental results were also presented which described the effect of fluid mobilities on the reservoir area contacted by the injected fluid at breakthrough for the five spot and direct line drive patterns. Most of the literature pertaining to sweepout pattern efficiency has emphasized the pattern which is obtained at breakthrough of the injected phase. The increase in the sweepout pattern which occurs after breakthrough

Jan 1, 1955

Development: Iron Ore In Peru Utah Construction Co., of San Francisco and a Peruvian Government corporation have signed an agreement for development of a large iron orebody in Peru. Most tests show 60 pct iron or better. Most of the ore is magnetite. Although ore will be shipped mainly to Eastern U. S. blast furnaces, shipments to the West Coast may develop as the orebody opens up. The construction firm indicated three American steel companies have shown interest in the project. The orebody is located 300 miles south of Lima and about 15 miles from the coast at the same longitude as New York City. Allen D. Christensen, executive vice-president of Utah Construction noted that the distance is shorter between Peru and the East Coast. The ore deposit measures about four to five miles in one direction and 10 miles in the other. As many as 15 outcroppings within these limits have been reported. Several of the outcroppings are thousands of feet long by several hundred feet wide, Christensen said. Shipments between 100,000 and 200,000 tons of ore per month are projected by the company. Cost of opening the mine to production may go over $5 million, Christensen said. It would include building of docks for ocean going vessels, housing, and heavy duty mining and processing equipment. The contract with the Peruvian government gives Utah Construction six to eight months for additional tests and a 20 year concession for mining the orebody. Peru will collect royalties on all ore. The company will also supply about 300,000 tons per year for an electric furnace to be installed by the Peruvian Government at Chimbote. No steel is produced in Peru now. Utah Construction formed the Argonaut Mining Co. last year, and was shipping iron ore from British Columbia to Japan at a rate of more than 50,000 tons a month, before winter weather decreased operations.

Jan 1, 1952

By Elmer W. Pehrson

THE founding of the American Institute of Mining Engineers in 1871 came at an unusually significant moment in the life of our country. The industrial revolution, in which mineral production played a major role, was just getting underway. The iron industry, established several decades earlier, was reaching sizable proportions. In 1871 pig-iron production was approaching 2 million tons, and the industry had spread as far west as Missouri and Wisconsin. The chief sources of iron ore were Pennsylvania, New Jersey, New York, and Michigan. The age of steel was in its infancy; production had not yet reached 100,000 tons per annum. The gold rush to California two decades earlier and the discovery of other gold and silver bonanzas in the West paved the way for the transcontinental railways, which were then being built and which contributed much to the subsequent development of the great copper, lead, and zinc districts of the Rocky Mountain area. Regular production of copper in the Michigan peninsula and of lead in Missouri and the upper Mississippi region had been established for many years but on a scale dwarfed by the quantities later required as technical progress, invention and enterprise made possible the rapid expansion of industry. Discovery of oil in Pennsylvania in 1859, the growing recognition of the

Jan 1, 1947

By AIME AIME

THE MODEL LAW previously referred to', in these columns several times, prepared by Engineering Council, to be o ered in any state where legislation is introduced for licensing engineers, is given in abstract below. , Mining engineers throughout the country should watch legislation of this sort and see that the draft prepared by Engineering Council is in the hands of any state legislative committee which proposes to frame a licensing law. So far as this office is informed, the mining engineers are a unit against licensing, but if we must be licensed the most innocuous law that has been submitted is the draft prepared by Engineering Council. ABSTRACT OF MODEL LAW -FOR REGISTRATION OF PROFESSIONAL ENGINEERS, ARCHITECTS, AND LAND SURVEYORS

Jan 1, 1920

By Harold L. Overton, Leonard B. Lipson

The first paper in this series1 outlined practical methods for applying the theory of steady-state flow of an ideal Bingham plastic liquid through a circular pipe and axially through a stationary concentric annulus to the enginekring analysis of friction loss problems. In the present paper the properties of another useful rheological model, the pseudoplastic generalized Newtonian liquid, are considered. The terminology applied to the rheological models is derived from the following classification of rheological models. The term "generalized Newtonian" is a class designation applied to models which do not have yield points but which exhibit a dependence on shear rate. The term "pseudoplastic" applies to a sub-group of models within this class which exhibit a decrease in "viscosity" with increasing shear rate. The term "power model" refers to a mathematical model proposed for describing the behavior of the pseudoplastic liquid. This model is of interest since certain of the salt saturated, oil emulsion, and "low solids" drilling fluids, inverted emulsion- and oil-base drilling fluids, aqueous gels, gelled crudes and blocking agents employed in hydraulic fracturing operations are of this type. The present treatment considers the equations describing steady-state Poiseuille flow through a circular pipe and a stationary concentric annul us, and Couette flow between concentric rotating cylinders for a particular pseudoplastic model. As in the previous paper' it is demonstrated how these equations can be applied to engineering calculations of friction losses. Graphical procedures for recovering the various flow curves and cxample calculations are included. A method for simplifying turbulent-flow correlations is also proposed. PROPERTIES OF PSEUDOPLASTIC GENERALIZED NEWTONIAN LIQUID In contrast to the Bingham plastic the generalized Newtonian liquid is yield point-free. However, in the flow region the relation between stress and rate of shear is not linear as it is with ordinary Newtonian fluids. If the stress increases with shear rate at a less than linear rate the system is called pseudoplastic. While there is no yield point in this system, the Bingham advocates' coined the term pseudoplastic to distinguish this kind of behavior from Bingham plastic behavior. For the pseudoplastic a plot of flow rate vs friction loss or rpm vs torque, from pipe flow or rotational viscometer measurements, respectively, generally has three qualities: (1) it can be clearly extrapolated toward the origin; (2) there is very little slope at the origin. This accounts for the high apparent viscosities at low mixing and pumping rates; and (3) the flow curve possesses a continuous curvature which gradually diminishes as the shear increases. Rheological measurements on a pseudoplastic liquid can be easily misinterpreted as indicating Bingham plastic behavior. A typical case in point is illustrated in Fig. 1. These data were obtained from measurements on an oil-emulsion mud using a commercially available rotational-type viscometer (Model 35 Fann V-G meter). Applying the "two-point"* method3 gives a plastic viscosity of 17 cp and a yield point of 24 lb/100 ft2; at the same time weighting material settles very easily in this system. This illustrates that it is not possible to distinguish between the pseudoplastic and the Bingham plastic from only two data points. It is possible to determine qualitatively which model is more appropriate by a combination of dynamic and static measurements. Experience indicates that the simplest criterion for the Bingham plastic liquid is that the calculated dynamic yield point should be of the same magnitude as the measured gel strengths. For the oil-emulsion drilling fluid illustrated in Fig. 1, a value of 4 lb/100 ft2 was obtained for gel strengths measured

By D. C. Porterfield

ProUuction of crude oil in Venezuela increased from 186,134,000 bbl. in 1940 to 2~8,131,ooo bbl. in 1941, or 22.6 per cent, to establish a new all-time high for the country. While the average production for the year was 625,000 bbl. per day, production during the month of December 1941 averaged 751,000 bbl. per day, and during the last week of the year, 766,000 bbl. per day. Production from the Lake Maracaibo basin averaged 454,000 bbl. per day during the year, or 72 per cent of the total for the country, compared with 73 per cent of the total produced in 1940. Drilling during the year was approximately on the same scale as in 1940, with 438 wells completed in 1941 as compared with 429 the year before. Exploratory completions decreased from 18 in 1940 to 6 in 1941. Of the drilling operations in 1941, 56 per cent was concentrated in the Lake Maracaibo basin and 44 per cent in eastern Venezuela, success being 98 per cent in the Lake basin and 83 per cent in the east. Successful completions for the country as a whole amounted to 92 per cent of the total wells drilled. Exploratory drilling in 1941 resulted in the discovery of three new fields, all in eastern Venezuela; viz., Guara, about II km. to the northeast of the Oficina field but on a separate structure; Santa Rosa, which is east of El Roble field on a structure forming a part of the major Santa -Ana- San Joaquin-El Roble uplift; and Santa Barbara, which is southwest of the Jusepin field on an extension of the main Jusepin anticline. At the close of the year three wildcats were drilling, all of which showed prospects of obtaining production; that is, Mercedes No, 2 in central Guarico, Las Ollas No. I on the Anzoategui-Guarico border near the town of Zaraza, and Quiamare No. I in Anzoategui northeast of the town of San Mateo. In spite of heavy withdrawals and the resultant natural decline in the potentials of older producing areas, new drilling during the year increased the potential production of the country from an estimated 780,000 bbl. per day at the end of 1940 to an estimated 810,000 bbl. per day at the end of 1941, or approximately 4 per cent. Since domestic consumption of petroleum products is insignificant compared with total production, exports of crude and products during the year increased in line with production. Crude exports totaled 196,800,000 bbl., compared with 158,400,-000 bbl. in 1940, and exports of products were 26,100,000 bbl., compared with 21,900,000 bbl. the year before. Exports of crude from Venezuela to the United States amounted to 36,500,000 bbl. In addition, about 2,200,000 bbl. was imported in bond into the United States for transfer to Canada. Total refining capacity of the country in 1941 was approximately 125,000 bbl. per day, including a crude-conversion plant with a capacity of 32,000 bbl. per day, capable of making fuel oil only. Three plants with a capacity of 121,000 bbl. Per

Jan 1, 1945

By Chester B. White

ARGENTINA is a country that has never been properly prospected. This is my settled conclusion after reporting on mines in this country ever since 1914, crossing all the mining provinces from Chubut, in the South, to the territory of Los Andes, in the North, chiefly on muleback. It is difficult and costly to get from one district to another. Apart from petroleum, some mineral discoveries have been made but they have been the result of casual rather than systematic work. In Neuquen, Mendoza, San Juan, Cordoba, La Rioja, Catamarca, and Los Andes attempts at mine development have resulted in failures, involving in each instance several million pesos.

Jan 1, 1937

By J. R. Dawson, A. B. Kinzel

THE purpose of testing is to determine whether the material in question is identical in all essential respects with similar material which has given satisfactory service. The most common method of securing such information is to select samples as representative of the entire material and subject them to destructive tests. As the welding industry grew, service data were accumulated and tests of welds took on new significance. New tests were devised and old tests modified so as to be more pertinent to welding. Moreover, in some cases the generally accepted procedure of testing by sampling is not accorded the same degree of confidence when applied to welds as in the usual applications. Thus, in instances where great hazard would be involved should the material fail, means of non-destructive testing have been sought with favorable results. Accordingly, tests used today may be divided into two groups, destructive and non-destructive tests.

Jan 1, 1930

By F. B. Plummer

THE practice of introducing acid into oil wells to increase production of oil and gas has been in use since 1894, when it was first used in the Pennsylvania. oil fields30.? It is only since 1928 that it has been used to any extent in the Mid-Continent18. The process has proved successful in increasing production, at least temporarily, in depleted oil fields where the producing formation is highly calcareous and where water drive is not too pronounced. In the Zwolle field in Louisiana, where the producing horizon is a chalk, increases of 100 per cent have been recorded25. In north-central Texas, where the oil is produced from the Marble Falls limestone, equally pronounced increases have resulted3. The production also in some fields yielding oil from quartz sand cemented with calcite has been benefited. The evidence of actual increase in total recovery of oil, however, has been questioned by some engineers18. It has been pointed out that the results of the treatment of a well in a new district, where the process has never been tried out, can never be predicted with certainty, since other factors besides percentage of calcareous content: of the oil sand play a large part in determining the success of the method. Numerous articles have been published on acid treatment and on the effects of acid on limestone1-35, yet very little has been written con-cerning experimental work on the actual effect, of acid on capillary pores and larger oil-coated voids of oil sands. This is due partly to difficulties in duplicating field conditions in a laboratory and partly to the fact that the process has been carried out largely by contracting companies that have been unwilling to publish details of their results for fear of loss of business to competitors. The authors, using equipment developed to measure the radial permeability of oil-sand cores29, have developed a method of investigating the results of acid treatment which has enabled

Jan 1, 1935

By A. Hansson, G. E. Tardiff

WHILE it is generally known that cold-worked low-and medium-carbon steels exhibit substantial increases in tensile rupture ductility with increased deformation velocity172 (up to the von Karman limit), the observations for annealed or normalized steel do not permit simple generalization. Various investigators, for example, have reported both small increases1,3 and small decreases4,5' in rupture ductility with increased rates of deformation of normalized low-carbon steel. The purpose of the present note is to report on the dependence observed for strain-aged steel since preliminary work here indicates that strain aging results in the development of a consistent type of behavior that is understandable in the light of current knowledge of the lower yield dynamics for steels which deform inhomogeneously.6 This realization throws additional light on the influences responsible for the behavior of normalized steel. The results presented here were obtained for a 0.21 pct C, 0.012 pct N sheet (0.012 in. thick) steel which was received in a temper-rolled condition (approximately 3 pct reduction in thickness after process annealing); the as-received material had a spherodized structure with a ferritic grain size of ASTM 8. The material was selected for testing after 6 months room temperature aging, at which time the static lower yield and ultimate tensile strength measured 79 and 82 kpsi, respectively. ASTM 2-in. reduced section, 1/2-in.-wide specimens were used in smooth bar tests and 3/4-in.-wide specimens containing two 60-deg opposed edge notches (root radii = 0.002 in.) were used in notched bar tests. To facilitate strain measurement, the smooth bars were blued with ink and marked at 0.1-in. intervals along the gage length; the notched

Jan 1, 1968

By W. R. Ingalls

THE following chronology presents the history of lead-mining in the United States in a brief form and is a useful reference in connection with the statistics of production 1621. Lead was mined and smelted near Falling Creek, Va., to supply the local demand for bullets and shot. This was the first mining and smelting of lead in what is now the United States. 1632. In a report made on the minerals of New England, lead-ore is mentioned. (Bishop, I., 470.) 1650. Supposed beginning of mining by Jesuits in Pima county, Ariz. 1651. Grant of lead-mine at Middletown, Conn., to Gov. John Winthrop.

Jan 9, 1907