Search Documents

By Robert Bell

THE " Tar-Sands." is the name which has been given to the extensive horizontal deposit of fine Cretaceous sand, blackened by tarry petroleum, which forms the banks of the last or lowest 130 miles of the Athabasca river before it terminates in Athabasca lake. The Cretaceous strata, to which these sands belong, extend northwesterly from Dakota all the way to this lake and for 500 miles beyond it. The Athabasca river forms the uppermost section of the Athabasca-Mackenzie, one of the great rivers of the world. It rises on the Pacific side of the Rocky mountains, westward of Edmonton, and flows north of east to a point called Athabasca. Landing, 100 miles north of Edmonton, where it turns northward and runs about 280 miles before it falls into the west end of Athabasca lake. The section of this river-system which discharges the lake just named into Great Slave lake, is called Slave river, and below the latter lake it becomes the Mackenzie river. Along the section of 280 miles of the Athabasca river above mentioned, the Cretaceous strata consist of bluish-gray and drab-gray marls, on top, from Athabasca Landing to Drowned rapid, 110 miles down stream; then heavily bedded gray sandstones, 225 ft. in greatest thickness, underlying these, form the banks for about 40 miles further. The strata appear to be horizontal, but they really clip very slightly to the southward. At Drowned rapid, we see the first of the tar-sands resting on almost horizontal beds of bluish-gray limestone of Devonian age. In some places the limestone is associated with shaly or marly bands. Notwithstanding the great hiatus between the two series, the horizontal tar-sands lie conformably upon the almost level upper beds of the limestone wherever the two formations are seen together, all along the river, throughout a

Mar 1, 1908

By Franklin H. Sharp, Kenneth L. Clifford

During the last few years the New Lead Belt of Southeastern Missouri has become the main source of lead in the United States. It also produces significant amounts of zinc, copper and silver. The mines are located on a narrow, mineralized trend extending southward from Viburnum, MG. for about 35 miles. The ore occurs as replacement deposits in the Bonneterre lime- stone formation which is about 1000 ft below the surface. In most of the mines, enough water is produced to supply the milling requirements without any reuse. There are dry areas, however, and at least two mills must rely on water reclaimed from their tailings lake to augment the mine water. These mills have no choice but to utilize recycled mill water.

Jan 7, 1973

By AIME AIME

DESPITE the fact that its membership is spread over every continent of the globe, the Petroleum Division was able to report a very substantial attendance at its meetings. Careful planning on the part of its chairman, J. B. Urnpleby, and his associates resulted in the presentation of a program that was of timely interest -and led to discussions that will unquestionably prove to be of major value to the petroleum engineer and to the oil industry in general. Scheduling of meetings so as to avoid all conflicts made it possible to obtain a higher average attendance at the several sessions* than in previous years, and gave everyone a chance to hear all of the papers that he was interested in. The chairmen of the various meetings are to be congratulated especially for their skill in handling them so that at .no time was there the least indication of lagging interest.

Jan 1, 1930

By Newell Hamilton

SOME years ago, in the manufacture of seamless tubing from an alloy steel containing 0.07 per cent maximum carbon, 18 per cent chromium and 8 per cent nickel, at the plant of The Babcock & Wilcox Tube Co., a peculiar type of piercing defect was noticed. This defect was definitely associated with certain heats of the alloy and was independent of any of the variables of mill operation and billet-heating condition. A thorough analysis of the defective material yielded but one clue to the reason for its abnormal behavior in piercing and that was its oxygen content as determined by the vacuum fusion method. The oxygen content of the defective 18-8 alloy was found to be from two to three times that of the material that had pierced satisfactorily, and this incited an active interest in the vacuum fusion method for the analysis of alloy steels. After a critical survey of the literature on this subject, and considerable experimentation, an apparatus and technique were evolved that gave a fairly rapid, simple and reliable method of analysis. Samples selected from six years of tube production of 18-8 and other corrosion-resistant alloys were analyzed by this method. This paper describes the procedure and gives a correlation of the oxygen, hydrogen and nitrogen contents of a number of alloy steel samples repre-sentative of good and bad tube-piercing quality.

Jan 1, 1934

By J. L. Martin, W. M. Campbell

A new electric logging method, called displacement logging, often gives a direct indication of the presence of mobile hydrocarbons in hydrocarbon-bearing formations. This method is based on the detection of a bank of connate water which is formed between the invading mud filtrate and virgin formation fluids in these cases. The existence of this phenomenon has beer, verified by laboratory studies and by actual field logs taken in known oil sands. INTRODUCTION During the past decade increasing use has been made of conventional electric logs to determine the amount of oil or gas in formations traversed by a borehole. This determination requires knowledge of several factors, such as true resistivity of the formation, formation factor, and water resistivity. Sometimes all of the factors necessary to make a reliable saturation calculation are not available. Also, the computations and corrections which are necessary in such a study often require the services of an experienced log analyst. It has long been the desire of exploration people to have a logging device which will locate hydrocarbon-bearing formations directly without requiring complex interpretation methods. The displacement log, while not completely fulfilling this desire, appears to be a Step in that direction. Basis for the Device The basis for this device stems from a phenomenon which occurs when mud filtrate invades a formation which contains displaceable hydrocarbons. As the mud filtrate invades the formation, most of the oil or gas is pushed out of the invaded zone, leaving residual oil. However, in addition to displacing most of the oil or gas, the connate water is also swept out, since the originally irreducible water is mobile in the presence of a water phase.1,2,3 Tonsequently, this irreducible water piles up as a bank between the virgin oil zone and the invading filtrate. If the mud filtrate is of higher resistivity than the formation water— as is commonly the case—the resulting annular zone, containing the bank of formation water, will be of lower resistivity than either the virgin oil-bearing formation resistivity or the invaded zone resistivity. This resistivity configuration, going from high to low to high again as the distance from the borehole increases, is found only in those zones which contain displaceable hydrocarbons. A device which would reliably detect this low resistivity zone would give a direct indication of mobile hydrocarbons. Illustrations This phenomenon is illustrated in Fig. 1 and 2. Fig. 1 shows a sketch of a zone containing salty connate water plus displaceable hydrocarbons, along with graphs showing fluid content and electrical resistivity vs distance from the borehole, before invasion occurs. Fig. 2 shows this zone, together with fluid content and resistivity graphs. after invasion by a fresh water mud. The resistivity pattern on moving away from the borehole is high: low: high. The absence of the low zone phenomenon in water zones is illustrated in Fig. 3 and 4. Fig. 3 shows a sketch of a zone containing salty formation water and residual oil, along with graphs showing fluid content and electrical resistivity vs distance from the borehole, before invasion occurs. Fig. 4 shows this water zone, together with fluid content and resistivity graphs, after invasion bv a fresh water mud. In this case the resistivity pattern on moving away from the borehole is high: low since there is no change in water saturation at the head ol

Jan 1, 1956

By C. E. Dobbin

THE identification of rock formations by a study of certain physical characteristics of burned samples was introduced in Wyoming in 1,926, when W. G. Buckles, superintendent. of the brick department of the Parco Development Co., reported to officials of the Producers & Refiners Corpn. that shales from the Cretaceous and older formations exposed between Parco and Rawlins exhibited distinctive coloration and textural features when burned in a standard brick kiln at temperatures ranging between 1000° and 3000° F. In collaboration with Elfred Beck, chief geologist of the Producers & Refiners Corpn., Buckles later burned cuttings and cores from several Wyoming wildcat wells in a standard kiln and successfully identified certain subsurface formations which had not been satisfactorily identified by other means. The results of their investigations were outlined in papers presented by Beck before the American Association of Petroleum Geologists at San Francisco in March, 1928, and by Buckles at. a joint meeting of the Rocky Mountain Oil and Gas Association and the Production Division of the American Petroleum Institute at Casper in November, 1928. These papers have not been published. The investigations set forth in this paper were carried out for. the purpose of determining the value of certain ceramic tests in assisting the petroleum engineers of the U. S. Geological Survey to identify well cuttings that represent Cretaceous shales penetrated beneath unconformable Tertiary formations in central, and eastern Wyoming, but that yield neither lithologic nor paleontologic criteria for satisfactory correlations with distinctive weathered outcrops. The investigations were made in the chemical laboratories of the Geological Survey at- Midwest, Wyo., and consisted of studying certain physical characteristics of burned bricks from representative outcrop samples of unweathered Cretaceous shales and of similarly burned cuttings of the same shales collected from wells in the Salt Creek oil field.

Jan 1, 1931

By Enrique Touceda

The question as to the proper amount of total carbon that the malleable founder would prefer to have in pig iron for use in the production of air-furnace, white iron castings, must be considered from different angles, that is, whether it is desirable or advantageous from an economic standpoint to use some kind of low-carbon scrap on his mixture, or make use of pig and sprue only. Whereas silicon is the acknowledged scrap carrier in the case of cupola gray iron castings, carbon performs this role for the most part in malleable iron practice, irrespective of the character of furnace used for the production of the white iron castings. In this particular, the advantage lies with the maker of gray iron castings in that the silicon content in pig iron through a regulation of furnace temperature is under very easy control by the blast-furnace manager, whereas he has little or no control over the resultant percentage of carbon, as this is dependent on the quantity of coke in the hearth, and hearth temperature, coupled with the amount of hearth slag and its particular composition. As perhaps more than 95 per cent. of white iron castings are made in air furnaces the following statements are intended to cover that situation particularly: In the malleable process the composition of the hard iron castings (that is determined upon as best suited for the work in hand) is the one factor that must control the composition of the mixture to be used; because if the elements are not between certain definite limits individually and collectively the annealed or finished product will be unsoitable, due, perhaps, to lack of sufficient strength or because it is too hard, to machine easily. The annealed product can be divided into two classes, one of which greatly predominates, that is, by far the largest tonnage is used for machine parts where high strength and ductility are essential requisites, while a far smaller amount, light in weight and thin in section, is used for other manufactured products in which castings of any reasonable degree of strength and ductility have proved satisfactory.

Jan 1, 1927

By P. D. Wilson

The Province of British Columbia covers 382,000 sq. mi., about 250,000 sq. mi. of which have not been prospected. In fact, the coast country and the islands are so heavily timbered and the surface covered with so thick a mantle of soil, muskeg, and, over broad areas, glacial drift, that prospecting and even trail breaking are extremely difficult. It is only along the coast or stream channels, or above the timber line, or where snow or rock slides have scoured the surface, that rock outcrops can be found. Glaciers nestle in many of the cirques and fill the valleys in the higher ranges. Great ice sheets and perpetual snow persist in certain localities, thus reducing the exposed areas worth prospecting. Almost the entire country has been subjected to intense glaciation, so that the conspicuous oxidized outcrops of orebodies typical of the southwestern United States and Mexico do not exist and surface bodies of enriched or oxidized ore are rare. With few exceptions, the mines1 of the Province are working primary ore. Development, have proved that some of these orebodies are large and important, although usually comparatively low in grade. Besides the few mines that have produced most of the minerals, there are many small mines, but their total output is unimportant. Considering the number of mines and prospects and the widespread mincralization, it is strange that no really great mines, comparable in sizc and richness with those in the western United States, have been found. The deposits that most closely approach the status of great mines are

Jan 1, 1923

By P. D. Wilson

The Province of British Columbia covers 382,000 sq. mi., about 250,000 sq. mi. of which have not been prospected. In fact, the coast country and the islands are so heavily timbered and the surface covered with so thick a mantle of soil, muskeg, and, over broad areas, glacial drift, that prospecting and even trail breaking are extremely difficult. It is only along the coast or stream channels, or above the timber line, or where snow or rock slides have scoured the surface, that rock outcrops can be found. Glaciers nestle in many of the cirques and fill the valleys in the higher ranges. Great ice sheets and perpetual snow persist in certain localities, thus reducing the exposed areas worth prospecting. Almost the entire country has been subjected to intense glaciation, so that the conspicuous oxidized outcrops of orebodies typical of the southwestern United States and Mexico do not exist and surface bodies of enriched or oxidized ore are rare. With few exceptions, the mines1 of the Province are working primary ore. Development, have proved that some of these orebodies are large and important, although usually comparatively low in grade. Besides the few mines that have produced most of the minerals, there are many small mines, but their total output is unimportant. Considering the number of mines and prospects and the widespread mincralization, it is strange that no really great mines, comparable in sizc and richness with those in the western United States, have been found. The deposits that most closely approach the status of great mines are

Jan 1, 1923

By S. A. Spachner

An analysis of the powder patterns of the omega transition phase in three binary titanium alloys containing 8 pct Cr, 13 pet Mo, and 15 pet V, respectively, showed that all could be indexed on an orthorhombic unit cell. The unit-cell dimensions were all quite similar. There is evidence for the occurrence of more than one transition phase in Ti-Cr and Ti-V alloys. FOLLOWING the discovery of a new brittle phase in certain titanium-chromium alloys by Frost, Parris, Hirsch, Doig, and Schwartz,' named ? by these investigators, much interest has developed concerning the identification of alloy systems in which this phase exists, kinetics of the transformation in such systems, and the crystal structure of the ? phases appearing. Omega has been found in alloys of titanium-manganese, titanium-molybdenum, titanium-iron,' and titanium-vanadium.' In the present work, a study was made of the powder patterns of the ? phase occurring in alloys of Ti-8Cr, Ti-13Mo and Ti-15V in an effort to obtain a basis of comparison for ? phases appearing in these different alloys. Comparison of Alloys for ?-Phases Two hundred mesh powders of Ti-8Cr, Ti-13Mo and Ti-15V were prepared. A portion of powder sufficient for three x-ray powder specimens was placed in a Vycor tube, evacuated to less than 0.1 µ pressure, filled with argon, and sealed. The tubes were then heated to 900°C, held at this temperature for 30 min, and water-quenched. Following this transformation to the ß phase, the specimens were quenched in lead or solder pots, held at the desired temperature for varying lengths of time and water-quenched. The heat-treatments used and the phases identified are listed in Table I. The intermediate water quench was used in lieu of direct downquenching from 900°C to the bath temperature desired to circumvent the possibility of transformation of the powder specimen from ß to (ß + a) while it was being moved from the homog-enization furnace to the lead bath. To check the possibility that upquenching to the bath temperature might bring into play a different mechanism than downquenching to this temperature, resistivity measurements were compared on Ti-8Cr rod specimens which were transformed isothermally at 400°C by downquenching from the solution-treatment temperature and those which were transformed at 400" C by upquenching ß specimens from room temperature. The results are shown in Fig. 1. No difference in transformation mechanism was noted. It soon became apparent that sufficiently detailed Debye-Scherrer photograms of the ? phase in the alloys which were to be used could not be obtained by the use of copper radiation. Although satisfactory photograms of ß and ß + a phases were obtained with this radiation, the ? phase appeared to exhibit mild fluorescence, making interplanar spacing computation virtually impossible. Molybdenum radiation appeared to offer promise in cutting down this fluorescent effect, the mass absorption of titanium for molybdenum radiation being 23.7 in contrast to 204 for copper radiation. The reduction in the accuracy in determining the location of the photo-gram lines caused by the shorter wave length of molybdenum characteristic radiation did not appear to be a significant factor. Utilizing a camera of 57.3 mm radius, best results were obtained for exposure times ranging between 30 and 40 hr. Tube potential

Jan 1, 1959

By R. B. Fuller, E. T. Casler

MANY changes were made in the methods and equipment used in the mining of pebble phosphate rock in the generation immediately preceding the present World War and it would be extremely interesting to note the improvements that will be made during the next generation. Literally, much water has gone over the dam since the days when we used local cordwood for generating steam and drying pebble phosphate rock. belt-driven centrifugal pumps operated by steam engines. and floating dipper or centrifugal dredges; when we removed overburden by small steam shovels and transported it by dinkey locomotives and six-yard cars; when washing machinery was installed on wooden structures the washers being replaced every four to six years. Those were the days when men were plentiful, and 47 different mining companies were selling their products, based on .decidedly meager information; and. like so many mining operations, little thought was given to conservation. As the importance of phosphate rock has become more prominent in the thoughts of our economists, a more intelligent approach has been made to mining problems. Vast improvements have been made in the technique and processing of the phosphate matrix and stripping of overburden, which, in turn, have brought developments in machines and equipment and a more

Jan 1, 1944

By Y. Nakada, E. J. Fasiska, A. S. Keh, L. Zwell

DURING an investigation of solid-solution hardening of nickel by carbon,' we found that there were no reliable data on the dilating effect of dissolved carbon on the unit cell of nickel. Bernier2 reported an increase in lattice parameter of nickel (3.523A) when an unknown amount of carbon was introduced into solid solution (3.536A). Similarly KG, Tsien, and Misek3 found an increase from 3.523 to 3.531A when nickel was carburized. strong4 studied the variation of nickel lattice constant as a function of dissolved carbon. However, in his case carbon was introduced into nickel by solidifying the melt at 65 kbar. Therefore, his carbon concentrations were much above the highest equilibrium solubility limit5 (2.7 at. pct C at 1 atm). Knowledge of the lattice mismatch between solute and solvent is essential in understanding the mechanism of solid-solution hardening. Therefore, we decided to determine the dilation of the nickel lattice by carbon under the more usual conditions of atmospheric pressure. The material used was Inco Electrolytic Nickel of 99.95 pct purity, as specified by the supplier. The impurity contents in wt pct were: Fe, 0.01; Cu, 0.01; Co, 0.03; 0, 0.005; C, Si, S, N, trace. To this base material various amounts of AUC-grade high-purity carbon were added during vacuum induction casting. Ingots, 2 in. in diam, were heated in a muffle furnace at 1000°C for i hr., hot-rolled to 1/2-in. thickness, and quenched into brine. All ingots with carbon concentration greater than 0.98 at. pct were enclosed in a cast iron box during the heating to minimize decar-burization. Small pieces were then either swaged down to 0.028-in.-diam wire or cold-rolled to 0.010-in.-thick sheets. After the final cold reduction in area of 50 pct, the specimens were recrystallized by heating in evacuated capsules at 1100°C for 60 to 80 sec and then quenched into brine. The final grain size was 50 to 100 µ. The carbon contents of the alloys, Table I, were determined by a combustion method

Jan 1, 1969

By E. J. KENNEDY

THE 142D MEETING of the Institute is rapidly shaping up with splendid prospects of a strong technical program and the lighter side of this annual occasion amply provided for. The date is February 20 to 23. The technical sessions will be held in the Engineering Societies building; the smoker-dinner, the informal dance, and the annual reception and dinner, at the Commodore Hotel, Monday, Tuesday and Wednesday respectively. The news to date on the technical side is as follows: Mining Methods-Subsidence The Mining Methods Committee has prepared an interesting program which will be divided into two sessions to be held early in the week. At the first there will be papers on mining methods and development, including a description of the "Sinking and Equipment of No. 2 Shaft at Minas de Matahambre," by Dudley D. Homer and R. H. Cromwell. They describe in considerable detail the equipment used and the practice followed in sinking this important shaft, giving detailed costs and performance figures. Hoist¬ing ?arrangements and mining practice at the "Red Ore Mines of the Woodward Iron Co. at Bessemer, Ala.," are described by Tenny C. DeSollar, superintendent of mines, in a second paper. At this session of the Mining Methods Committee, H. M. Roche and R. E. Crockett, of the Committee on Eastern Magnetite Mining and Milling Methods, will present their paper, "Iron Ore Mining at the Scrub Oak Mine." This mine is in the highlands of New Jersey about 40 miles west of New York City. Prof. Robert K. Warner of Yale University will present a paper on "The Selection of a Mining System," which should have an interesting discussion. Pierre R. Hines, of Portland, Ore., will present, with stereopticon slides, his paper on "The Owyhee Tunnels, U. S. Reclamation Project, Owyhee, Oregon," describing one of the recent irrigation undertakings.

Jan 1, 1933

R. V. Norris, Wilkes-Barre, Pa. (communication to the Secretary*):—Mr. Stow's paper presents a series of arguments, numbered from 1 to 18, concerning the relative merits of four systems of colliery-ventilation, designated by the author as " plain pressure-ventilation," " plain exhaust-ventilation," " obstructed pressure-ventilation," and " obstructed exhaust-ventilation." These arguments are subsequently compared by means of tables, in which an arbitrary numerical value is assigned to each, and which consequently serve no other purpose than that of showing his opinions and predilections, as indicated by his assignment of the said numerical values. In addition to this general summary, Mr. Stow intimates his preference for a fifth method of colliery-ventilation—namely, what he calls " alternating pressure-ventilation," which consists in the running of the fan at "pressure " during working-hours, and as an " exhaust" between shifts—a system which he proposes as, perhaps, new, yet which he thinks deserves recognition " as a standard form." This proposed " standard form " is not to be found in practice ; and I think it would be impracticable in gaseous mines of large extent, for the following reasons: 1. It takes considerable time to reverse the air-current in a large mine; and the reversal would involve a period of complete stoppage of ventilation, long enough to permit serious accumulations of gas. 2. In shaft- and slope-mines, at least, it is hardly practicable to have " every man out of the mine" during the night, and certainly impracticable to avoid keeping mules and horses inside. 3. The doors necessary to divide and direct the air-current are properly hung to open against the air-pressure; and, unless

Jan 1, 1910

By R. W. Bartlett

DISILICIDE coatings, MeSi2, on refractory metals are usually grown by a solid-state diffusion reaction similar to the parabolic oxidation of metals. Two or more silicide compounds occur in each of the binary silicon-refractory metal systems. When an adequate source of silicon is available during the coating process, the lower silicide compounds are usually not formed.1 However, during service application of the coated refractory metal, continued heating causes further diffusion and growth of the lower silicides. A study of the growth kinetics of the lower silicides in the molybdenum and tungsten binary systems with silicon was previously reported.2 The present study is concerned with the growth kinetics of Ta5Si3 and Cb5Si3, formed as conjugate layers between TaSi2/Ta and CbSi2/Cb diffusion couples, respectively. Diffusion couples consisting of disilicide-coated tantalum and columbium sheet coupons were subjected to diffusion heat treatments, cross-sectioned, and scanned by an electron-microprobe analyzer to determine the relative X-ray intensity profiles. These profiles correspond closely to concentration profiles for the constituents, and were used to identify phases and locate phase boundaries. The analysis of a single specimen after a diffusion-anneal provides only one value for the Me5Si3 phase thickness, corresponding to the time and temperature of the diffusion treatment. Consequently, each isothermal curve showing the rate of accumulation or depletion of silicide phases required several samples with identical diffusion temperatures but different diffusion times. The disilicide coatings were prepared by pyrolizing commercially pure silane in a hydrogen carrier gas. The hydrogen was purified by passage through a palladium membrane. Commercially pure tantalum and columbium sheet metal coupons, 0.005 by $ by 2 in., were used. All of the coated specimens for each system were prepared together in a single group in order to minimize coating variations among individual specimens. During pyrolysis, the brightness temperature was maintained at 1200°C. With suitable flow rates at this temperature, only the disilicides of tantalum and columbium were formed in detectable amounts. Coated specimens were subjected to diffusion an-neals in a tube furnace with automatic proportional control within ±10°C. A H2-Ar mixture, deoxidized and dried over anhydrous magnesium perchlorate, was used to prevent oxidation during the diffusion anneal. Diffusion couples were cross-sectioned, polished and examined with an A.R.L. electron-microprobe X-ray analyzer. Both metal constituents in each specimen were simultaneously scanned using a 1-p beam spot size and either 1- or 2-µ steps. Analyses were performed using the Ka radiation of columbium and silicon, and the La, radiation of tantalum. For all specimens, an acceleration voltage of 30 kv was used, and integration was made against the specimen current. LiF and A DP monochrometers were used to isolate characteristic radiations. Three or more traverses were made on each specimen. The intensity scales were adjusted using the constituent metals and standard samples of the silicide compounds which had been verified by X-ray diffraction. The relative intensity profiles were used directly, in conjunction with the standard samples, to identify compounds and phase boundaries. The stoichiometries differ considerably between the silicide compounds in both systems, and the homogeneity range for these silicide compounds is narrow. These characteristics result in marked differences in relative intensities of the fluorescing elements—differences which permit ready identification of phases and phase boundaries. Projections of both electron back-scattered images and characteristic

Jan 1, 1967

By Paul Merica

ONE of the most useful, and at the same time least commonly used, methods of thermal analysis for the determination of transformations in metals and alloys consists in the recording of the tune intervals required for successive increments of temperature change during heating or cooling, the temperature of the furnace containing the specimen being altered at a uniform rate. The curve obtained by plotting these time intervals as a function of the mean temperature of the specimen during the interval is called the inverse-rate curve. It is probably due to the fact that no simple and convenient method has apparently been available for the measurement of the successive time intervals that this method has not been so generally used as, for example, the differential method, for which several tykes of automatic or semi-automatic apparatus have been designed. Whenever this method has been used, the intervals have usually been measured with the use of a chronograph; its operation as practised at the Bureau of Standards' is as follows: The temperature of the specimen is measured by a thermocouple and a dial potentiometer. The operator sets the potentiometer at successive values of the electromotive force differing by equal increments, usually 0.02 millivolt, and records the exact instant on the chronograph, by pressing a contact key, at which the galvanometer coil passes through its null position. Two-second intervals are also recorded on the chronograph record, and the number of 'seconds elapsing between successive signals is afterward counted from the record and plotted as a function of the electromotive force or of the temperature. This is an admirable method and by it most minute thermal arrests may be detected, but it requires a good chronograph, which is generally difficult to obtain, and the time of one operator during the recording and, subsequently, to read the intervals from the record; the latter operation often takes from one to two hours.

Jan 7, 1919

By C. H. Wayman, D. W. Fuerstenau

THE gas phase is one of the indispensible ingredients in flotation operations. Flotation depends on the collision of an air bubble and a mineral particle in a pulp and their ability to remain in contact long enough for adherence to take place. Before it is possible to understand the mechanics of air bubble-mineral particle encounter, it is necessary to learn more about the nature of bubbles themselves before collision with a mineral particle has taken place. To date, little work has been done on air bubbles in flotation systems. In 1945 Fahrenwald1 presented a study of the role of frothers on air bubbles and on aeration in flotation, and recently Wark and Sutherland2 discussed the work of Rosenberg3 in relation to flotation. The research reported in this present article was undertaken to investigate systematically the effect of bubble size and the concentration of certain reagents on the terminal velocity, shape, path, and drag coefficient of single bubbles in distilled water. Most of the work is concerned with the effect of a-terpineol on bubble motion in water, but studies were made with potassium chloride, potassium hydroxide, potassium ethyl xanthate, and potassium amyl xanthate.

Jan 6, 1958

JOHN H . NELSON,*Worcester, Mass.-In reply to the question "Is there any final information in regard to the relation between the temperature or the rate of cooling of a piece of heat-treated steel from the drawing temperature, and the so-called notch toughness?" I might say that we have conducted a large series of tests in the study of impacts on chrome-nickel and carbon steels and have gone into the subject of quenching from drawing temperature quite thoroughly but have found that one cannot lay down any definite rule or law with respect to the effect of quenching from the drawing heat. We conducted experiments on the effect of cooling by quenching in water, cooling in air, and burying the coupon in lime. Steels that have practically no impact value when air cooled may show very marked results when they are quenched in water, depending on the temperature at which the drawing is done.

Jan 6, 1919

By G. E. McElroy

Though air jets occupy only a minor role in the ventilation of mines and other enclosures, their importance in this respect is greater than is commonly recognized and may be considerably increased as our conception of their modes of operation becomes clearer. The object of this paper is to discuss some of the ways in which air jets are involved in mine ventilation and some possible applications to the ventilation of mines and other enclosed spaces. The mention of air jets ordinarily suggests the use of some form of an air injector, such as the Venturi blower occasionally used for auxiliary ventilation in mines, or the Saccardo (injector) system used to a limited extent for ventilating railroad tunnels. Actually, the term covers such common phenomena as the discharge of air from fan pipes and coal-mine line brattices, and even from smoke stacks and fans. A knowledge of the general mode of air entrainment by jets also helps to explain certain phenomena—some mine-gas explosions, for instance—that otherwise would remain obscure. Jet action has been involved in three recent series of Bureau of Mines experi-ments in which the author has participated: experiments on fan-pipe discharge, On the dilution of gases discharged from a stack and On the ventilation of a ship's hold. Available data on the discharge of jets into large openings and on the design and performance of air injectors have been analyzed in considerable detail and supplementary experiments are planned for after the war. The results of the fan-pipe experiments have been combined with the analyses of data on jet discharge into large spaces, and have been published.' The results of the stack-gas dilution tests, which refer to a jet discharged into a crosswind, have also been published2 and a paper on the design and performance of injectors has been prepared for publication.3 These technical experiments and analyses form the background and the documented evidence for the following nontechnical discussion of the use of air jets in mine ventilation. Jet Characteristics The jets commonly encountered are those in which the air is in turbulent— as opposed to laminar, or streamline-— motion. The characteristics under discussion apply only to such turbulent jets and have their basis in theories of the mixing of turbulent air currents. Such jets have basic characteristics that are present, though variable in form, regardless of whether the jet expands freely in space, whether the expansion is limited by adjacent walls, or whether the jet propels air through a flow circuit. They expand at definite angles and entrain the surrounding air, even though the entrained air must be obtained by recirculation of their own air streams. As the quantity of air in motion in the mixed stream increases, the average velocity of the stream decreases.

Jan 1, 1946

By C. B. Foraker

THE Magma mine, of the Magma Copper Co., at Superior, Pinal County, Arizona, is 68 miles east of Phoenix and 21 miles west of Miami, Arizona, on highway U. S. 180. Temperatures and Underground Waters Surface Temperatures.—The average surface dry-bulb temperature at Superior is 72.4°; wet-bulb, 57.4°; with an indicated relative humidity of 38 per cent. The average yearly rainfall from 1921 to 1936, inclusive, was 18.74 in. The maximum condition of the atmosphere is in June, July and August, and the minimum is in January and February. The surface temperatures, of course, influence the temperatures of the downcast shafts; however, the variation between winter and summer causes a difference of only 2" to 3" in the stopes and working places that are not close to the intake shafts. Average atmospheric conditions are shown in Fig. 1. Rock Temperatures.—Rock temperatures on the deeper levels of the mine are as follows:

Jan 1, 1940