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By E. Gaujot

IN connection with the question of coal waste and economy in mining, we would call the attention of those interested to an apparatus invented by M. Dernencourt, Superintendent of the Anzin Division of the Anzin Coal Company, North of France. This apparatus is known in France and Belgium under the name of prop screw jack (vis botte), and has been used with good results in the above-named countries for some years past. M. Ponson gives, in his " Traité de l'exploitation des Mines," a description of it (page 533), but as the description given is old, the work not widely known in this country, and as some valuable improvements have been made since, I thought it might be useful to give a description of it, having seen it in operation in 1867, while in Europe to attend the great Exposition, and on a scientific tour to the mining districts of France, Germany, Belgium, and Italy. The prop screw jack is composed of the following pieces: I. The body or column B, Fig. 4 [Plate (1)], of oak or yellow pine, sawed square, the bark taken off, and any length, proportionate to the vein. The smallest are 10 inches diameter at the base, and 9 inches at the top, the height being from 12 to 15 inches less than the size of the vein. In the axis of this column, and at the top end, is a cylindrical opening or hole, C, 2 3/4 inches diameter, 10 inches deep, for the screw, S. II. Two wrought-iron rings, R R, to strengthen the two extremities of the column ; the rings must be put on hot. III. A cast-iron washer, E, with hole in centre a little larger than the screw, to be put on the top of the column, and on which the nut is to rest; the top side of this washer must be faced on the lathe, also the bottom of the nut, to prevent friction. IV. The screw, S, having a total length of 12 inches and a diameter of 21/2 inches (for very high veins this diameter may be in¬creased to 3 inches), and has on its top a wrought-iron plate, T,

Jan 1, 1873

By Wm. Hamilton Merritt

IN this paper, which I have the honor to submit to the Institute, it is my intention to treat especially of that part of the North Staffordshire field which converges to a long tongue in the neighborhood of Congleton, and which includes the villages of New Chapel, Ford Green, Norton, Biddulph, Bradley Green, Gillow Heath, and the immediate vicinity. My object is not so much to give a minute description of the geology or systems of mining and smelting, as by a general review, some idea of the extraordinary facilities for the production of excellent iron, which have enabled this district to maintain its position more successfully than any of its rivals against the late depression in trade. The North Staffordshire coal field has the Cheshire and Lancashire fields some thirty-five miles to the north, those of Derbyshire and Nottinghamshire forty miles to the east, those of South Staffordshire and Shropshire, about thirty miles to the south, and the Denbighshire and Flintshire fields some forty miles to the west. It is highly probable that the coal continues under the new red sandstone to the Western and Southern fields as the dips on both sides, and absence of large faults, make it impossible to come to any other conclusion. In a section of this coal field, from Chatterly to Whitfield, thirty-two workable seams of coal are shown, of an aggregate thickness of 130 feet, varying from 2 feet 6 inches to 7 feet, and thirteen seams of ironstone, 24 feet, averaging from 2 to 4 feet. All of these seams have been minutely described in a paper by Mr. Charles J. Homer, read in 1875 before the British Iron and Steel Institute. In the northern part, to which I especially wish to direct your attention, the beds lie in a V-shaped basin, the underlying millstone grit and Yoredale rocks rising and forming escarpments on either side of the valley containing the coal. Throughout this district, at the outcrop of the coal, there are indications of old workings. A shaft 4 to 5 feet in diameter reaches the coal at about 14 yards from the surface, and from it the coal has

Jan 1, 1880

By William Hamilton Merritt

In this paper, which I have the honor to submit to the Institute, it is my intention to treat especially of that part of the North Staffordshire field which converges to a long tongue in the neighborhood of Congleton, and which includes the villages of New Chapel, Ford Green, Norton, Biddulph, Bradley Green, Gillow Heath, and the immediate vicinity. My object-is not so much to give a minute description of the geology or systems of mining and smelting, as by a general review, some idea of the extraordinary facilities for the production of excellent iron, which have enabled this district to maintain its position more successfully than any of its rivals against the late depression in trade. The North Staffordshire coal field has the Cheshire and Laucashire fields some thirty-five miles to the north, those of Derbyshire and Nottinghamshire forty miles to the east, those of South Staffordshire and Shropshire, about thirty miles to the south, and the Denbighshire and Flintshire fields some forty miles to the west. It is highly probable that the coal continues under the new red sandstone to the Western and Southern fields as the dips on both sides, and absence of large faults, make it impossible to come to any other conclusion. In a section of this coal field, from Chatterly to Whitfield, thirtytwo workable seams of coal are shown, of an aggregate thickness of 130 feet, varying from 2 feet 6 inches to 7 feet, and thirteen seams of ironstone, 24 feet, averaging from 2 to 4 feet. All of these seams have been minutely described in a paper by Mr. Charles J. Homer, read in 1875 before the British Iron and Steel Institute. In the northern part, to which I especially wish to direct your attention, the beds lie in a V-shaped basin, the underlying millstone grit and Yoredale rocks rising and forming escarpments on either side of the valley containing the coal. Throughout this district, at the outcrop of the coal, there are indications of old workings. A shaft 4 to 5 feet in diameter reaches the coal at about 14 yards from the surface, and from it the coal has

Jan 1, 1880

By Arnold Hague

At the Buffalo meeting, October, 1888, Dr. Raymond presented a paper entitled: "Soaping Geysers" (p. 449 of the present volume), in which he called attention to the use of soap by tourists to cause eruptions of several of the well-known geysers in the Yellowstone Park. Incorporated in this paper appears a communication received from me, written from camp in the Park, in reply to some inquiries on the subject. The letter discussed somewhat briefly the means employed by visitors to the Park to hasten the eruptions from hot springs and reservoirs of hot water, which remain dormant for days, or even weeks or months, at a temperature near the boiling-point, without any display of geyser-action. As the paper has called forth considerable comment, I desire to elucidate one or two points in relation to the temperature of the springs, and to answer some inquiries about the composition of the thermal waters. In the summer of 1885, a Chinaman, employed as a laundryman for the accommodation of the tourists at the Upper Geyser Basin, accidently discovered, much to bis amazement, that soap thrown into the spring from which he was accustomed to draw his supply of water produced an eruption in every way similar to the actual workings of a geyser. Tourists with limited time at their command, who had travelled thousands of miles to look upon the wonders of the Yellowstone, soon fell into the way of coaxing the laundryman's spring into action, to partly compensate them for their sore disappointment in witnessing only the periodical eruptions of Old Faithful. Successful attempts upon this spring soon led to various endeavors to accelerate action in the dormant and more famous geysers. In a short time, so popular became the desire to stimulate geysers in this way, that the Park authorities were compelled to enforce rigidly the rule against throwing objects of any kind into the springs. In connection with a thorough investigation of the thermal waters of the Yellowstone Park and the phenomena of the geysers, I undertook a number of experiments to ascertain the action of soap upon the waters and to determine, if possible, those physical conditions of various pools and reservoirs which permitted the hastening of an

Jan 1, 1889

By T. R. Braithwaite

The brief comments made in this chapter deal mainly with shaft sinking, but don't assume that freezing techniques apply only to shaft sinking. They can be used on tunnel work, on such things as liquid gas storage in sediment, and I think you will probably see other applications for it as we go along. The method was first developed in 1883 and was used to sink shallow shafts through water-bearing overburden in Germany and in England. One of the early shafts was in Germany and was sunk by freezing to 310-ft depth. The project required 17 months for drilling, roughly 5 1/2 months for freezing, and another 7 months for sinking, giving an average progress of 10 ½ fpm. Fortunately there have been numerous improvements and new developments in this technique through the years. With equipment and techniques available today, we can take a 20-ft-diam shaft down through 2000 ft of water-saturated overburden and the time schedule runs roughly 4 months for site preparation, freeze-hole drilling, installing the casings, and setting up the plant; 4 ½ months for freezing; and 6 months for excavating and installing permanent linings. This gives a progress rate of about 140 fpm, on average. I might qualify that a little in that the special linings that are required for some formations can affect the time. If it's straightforward sinking where one can use a heavy concrete lining, up to 630-640 fpm may be achieved in a shaft; but with special cast-iron tubbing or types like that, 5 fpd is pretty good progress, so the lining does affect the time. The freezing method is used mainly for sinking shafts through unstable water-bearing formations which cannot be grouted either effectively or economically and which are too deep to enclose in pile casing. Even with overburden, grouting methods available today can handle roughly 100 lb water pressure; in the range of, say, 100 to 150 ft from the surface, it's very often best to grout 40 or 50 ft. You normally drive a pile casing and go through it. Below that range, freezing is very often the economical

Jan 1, 1970

By M. E. Fine

IN the apparatus for measuring internal friction shown in fig. 1, a modification of that described by Kê,1,2 the parasitic energy loss or background is equivalent to a Q-1 of approximately 4x10-5. This low value of background was obtained by using a jeweler's collet of appropriate size for the upper support, eliminating lateral motion without immersing the bob in oil, and designing the bob to reduce air resistance. The pendulum is supported on the frame through a snug fitting, sliding rotary joint (fig. I-B). A slight twist of the top imparts essentially pure torsional motion to the pendulum. No evidence of energy loss in the sliding joint has been observed. In the bob (E) steel balls are used in the torsion arm, and the bottom is filled with lead giving a total weight of 94 g. A lighter bob may be used for small diameter specimens. Another bob was a solid disc with provision for adding discs to change the frequency. The oscillating image of the filament is recorded on a revolving drum camera (fig. 1-3) driven by a synchronous motor. This allows use of frequencies higher than can be measured visually on a glass scale. Samples varying in diameter from 0.020 to 0.075 in. have been measured, the frequencies have ranged from 1 to 12 cps, and the maximum strain varied from 0.5 to 10x10-5. With appropriate modification the sample may be placed in a thermostat. The apparatus may also be used to measure the shear modulus. In the examples of measurement given in table I the internal friction of Permendur and the 46.8 Ni-Fe alloy are due, for the most part, to magneto-mechanical hysteresis8 (elastic hysteresis accompanying stress-induced magnetostriction) which depends on strain amplitude and increases with annealing. The internal friction of most materials decreases with annealing. References IT. S. K6: Physics Review (1947) 71, 533. 2 T. S. Kê: Transactions AIME (1948) 176, 448; Metals Technology (June 1948) TP 23703. 3 R. Becker and W. Döring: Ferromagnetismus. 365 (1939). J. Springer.

Jan 1, 1951

By R. M. Treco

THE thermal expansion of pure beryllium was first investigated by Hidnert and Sweeneyl in 1925 on a single cast specimen stated to be of 98.9 pct purity. A study of the coefficients of expansion by X-ray methods has recently been made by P. Gordon' on powder obtained from the Brush Beryllium Co. assaying 97 wt pct beryllium with about 2 wt pct oxygen as an impurity. The present work pertains to about the highest purity metal obtainable from the Brush Beryllium Co. This metal was in the form of lumps which were remelted and cast in a high-vacuum induction furnace. Expansion data in this paper deal with beryllium extruded into bars of rectangular cross-section 4x1/2 in. and the anisotropic expansivity of a large cast single crystal. Analysis of the cast metal after extrusion indicated a beryllium assay of 99.28 pct. Impurities were 0.170 pct Fe, 0.140 pct Al, 0.014 pct Mg, 0.086 pct Si, 0.020 pct Cu, 0.020 pct Mn, 0.007 pct Ni, 0.007 pct Ca, 0.080 pct C, 0.179 pct 0, (as BeO). Part I—Extruded Metal Thermal expansion measurements were obtained with a fused quartz-tube differential type dilatom-eter3 on specimens cut from the extruded sections in longitudinal and transverse directions. Specimens were machined to a diameter of 0.250 in. and a length of 3.000 in. One sample from each direction was vacuum annealed for 1 hr at 800°C. The dilatometer tube was placed in a vertical tube furnace having a uniform temperature zone which was twice the length of the sample. Average time for a complete thermal cycle to 500°C was 18 hr. Temperatures were observed with two chromel-alumel thermocouples attached to the sample about 1 M in. apart. The accuracy of temperature measure-ment was ± 0.25°C. An argon gas atmosphere sur-rounded the specimen to prevent oxidation of the beryllium. Samples were identified as shown in table I. Results - The original plan included measuring expansion up to 1000°C, but the first two runs on sample No. 5 showed that a permanent contraction occurred from

Jan 1, 1951

By R. V. Wheeler

A matter of much concern at present to the coal-mining industry of Great Britain is the effect of the working of the Coal Mines Act, 1930. This Act, which received the Royal Assent on Aug. 1, 1930, contains five parts: (1) production, supply and sale of coal; (11) the reorganization of the coal-mining industry; (111) hours of work; (IV) the Coal Mines National Industrial Board; (V) general. The first three parts are of major interest and discussion can be confined to them. Part I.—Production, Supply and Sale of Coal Under Part I of the Coal Mines Act, 1930, provision is made for central and district schemes to regulate the production, supply and sale of coal by the fixation of standard tonnage, quota and minimum prices. By Nov. 1, 1930, all the district schemes came into force with the exception of that for Scotland, where the majority of the coal-owners did not see their way to accept the amendments to their draft scheme demanded by the Mines Department. A compulsory scheme for Scotland was thereupon prepared by the Mines Department and put into force on Nov. 24, 1930. It is administered by the coal-owners of the district. The essence of the schemes is the allocation of tonnage for each district by a Central Council, and the allocation of quota for each pit in a district by an Executive Board for that district. Up to Dec. 31, 1930, the various bodies of coal-owners engaged in administering the schemes were employed in work preliminary to their full operation. Standard tonnages had to be determined and coals had to be classified. In consequence, it was not found possible to put the regulation of output into force until Jan. 1, 1931. The determination of minimum prices proved to be an even longer process, and only in a few districts were minimum price schedules operative during the first quarter of this year. The working of the schemes during the March quarter, 1931, has been reviewed in an official publication by the Mines Department,' which can be summarized as follows:

Jan 1, 1932

The members of the Institute have probably seen in the daily papers notices of the plans of the Secretary of the Navy to. form an Advisory Board to assist the Government to make available the latest inventive genius of the country. Secretary Daniels has appointed Mr. Thomas A. Edison Chairman of this Advisory Board and has officially invited the Institute to secure the selection of two of its members to serve. on this Board. The Secretary in his letter states: "I feel that the work your Institute has done has been such as to give it the right to be in a way officially represented, and the Navy Department desires in this way to testify to its own appreciation of the splendid work for our country that your Institute has done. I have the emphatic approval of Mr. Edison, and he agrees entirely with me that your Institute should he represented in this way and that no better method of getting the kind of men we need could be devised." The invitation of the Secretary of the Navy has been officially accepted and steps have been taken to nominate the two members. Since the Constitution provides for no meeting of the Board of Directors until September, and as Secretary Daniels urged early action, the matter was discussed at a special meeting of the Executive Committee of the Institute, at which were present as many members of the Board of Directors as were in New York City at the time. Invitations were also extended to other members of the Institute who happened to be in the vicinity. At this meeting it was decided to submit the matter by a special letter-ballot to the Board of Directors and in doing so to suggest or nominate five members of the Institute, accompanying this nomination with the statement that the Directors might vote for two of the members so nominated or for any other members of the Institute not so nominated. It was voted at this meeting that it. was the sense of those present that in view of the fact that this committee was an advisory one the type of men to be chosen should be men of administrative or executive ability, cap-

Jan 9, 1915

By Horace F. Silliman, Curtis L. Wilson, Eugene C. Little

The change in electrical resistance and Rockwell hardness (16-100-B) of copper alloys containing Ni2Si and Co2Si was determined by annealing the quenched solid solutions at various temperatures for various lengths of time. The rate of precipitation of Nisi, as measured by the rate of decrease of electrical resistance and increase of hardness, increased with annealing temperature up to a certain point, depending on the percentage of Ni2Si present. At these temperatures discontinuities in the rate: change occurred. Similar discontinuities in the Co2Si alloys were no The solubility of Co2Si in copper was found to be 5 per cent at 970" DISCUSSION (Robert F. Mehl presiding) R. I?. Mehl, Pittsburgh, Pa. (written discussion).—The electrical conductivity and hardness curves reported in this paper are interesting, particularly because many of the anomalies of the precipitation processes are evident from such curves. The title of the paper, however, is deceptive, for it implies that measurements of electrical conductivity and hardness are suitable to determine the rate of precipitation. Neither of these methods is suitable for a quantitative measurement of rates of reaction or of precipitation in the solid state. Electrical conductivity in some alloys shows an anomalous increase during the first stages of aging at low temperatures; it is notably sensitive to strain and to state of subdivision. I have plotted the conductivity curve representing the decomposition of the phase at 555" C. in the copper-aluminum system, given in the paper by Smith and Lindlief (Fig. 47, p. 93) as a rate of reaction curve, and compared it with the curve determined by area evaluation (Fig. 7); these two curves are not coincident. Hardness is likewise very uncertain, for it is so much dependent upon particle size. Of the various methods proposed for the study of rates of reaction and precipitation, the evaluation of volume of reaction product from the respective area of matrix and reaction product on the photomicrograph is the most trustworthy; suffering, perhaps, only from low sensitivity during the early stages. This method, used originally by Davenport and Bain and now by Smith and Lindlief, is suitable for

Jan 1, 1933

By William H. Baer, George M. Carlton, Blake M. Loring

IT is a well known fact that age-hardening alloys remain in a supersaturated, or partially supersaturated, condition only for limited periods of time at temperatures below the solvus. In order to develop optimum properties by subjecting the quenched alloy to precipitation or age-hardening treatment at a specified temperature, it is necessary that the cooling rate be sufficiently high to maintain the required degree of supersaturation of the solid solution. In practical applications the size and shape of the specimens obviously have considerable influence on the rate of cooling and there is need for more information on the effects of various rates of cooling. Cooling rates of quenched aluminum alloys generally have been established by the type of quenching medium, the temperature of the medium and the dimensions of the specimen.1,2,3 Except for the work of Roth3 little quantitative information is available on the measurement of cooling rates of aluminum alloys and the significance of the influence of various cooling rates upon the mechanical properties. The purpose of the present investigation was to study the use of the Jominy test for aluminum alloys (Table I). EXPERIMENTAL PROCEDURE The material for this investigation consisted of extruded rods 1 ¼ to 1 ½ in. in diam. The chemical compositions were as follows: [ ] The modified L-type Jominy specimen with dimensions shown in Fig I was selected as the most convenient means for obtaining a wide range of cooling rates. The standard Jominy specimen was not satisfactory because its cooling rate was not sufficiently high. The four flat surfaces machined at right angles along the length of the L-type specimen to a depth of 0-015 in. facilitated the hardness measurements. The specimens were machined from the extruded stock with no intermediate forging. New specimens were used for each aging experiment. The specimens were given solution treatments of 2 hr duration at recommended temperatures in a Hoskins furnace (Table 2). The temperature of the furnace was maintained constant to ±3°C. No protective atmosphere was necessary because the thin film of oxide that formed on the surface of the specimens had no effect on the hardness measurements.

Jan 1, 1948

By Ben. B. Cox

The principal events during the year consisted in the exploitation of the Kirkuk field, the regular operation of the four-million-ton pipe line to the Mediterranean, and the discovery of low-gravity oil on three other structures in the West Tigris (Shergat) area. The Iraq Petroleum Co., Ltd. continued the systematic exploitation and exploration of its Kirkuk field, maintaining a carefully unitized operation. Bottom-hole pressure differentials and low gas-oil ratios were maintained. All crude was produced by flowing The cleaning up following the construction of the Mediterranean pipe line, which began deliveries in August, 1934, was completed during the first quarter of 1935. The line easily maintained its rated capacity for the remainder of the year. The Mosul Oilfields, Ltd., through its operating subsidiary, the B.O.D., Ltd., expanded its exploratory organization from 9 to 16 drilling rigs and discovercd 20" A.P.I. crude on the Sadid, Hibbarah and Qasab anticlines. Whether these discoveries will be commercial pools remains to be proved. The Qaiyarah-Najmah-Jawan field, which was discovered by the I.P.C. in 1928, was extended arid production was found in the Eo-Cretaceous as well as the "Main Limestone" (Eocene, Oligocene and Lower Miocene). Gas caps were found under each of the crests of the West Tigris structures. Negotiations are in progress between the Mosul Oilfields, Ltd. and the Iraq Government for the extension of the Anatolian Railway from the Turkish border to Mosul, with a view to tanking the heavy West Tigris crude to the Mediterranean. The subsidiary of the Anglo-Iranian Oil Co., Ltd.', the Khanaqin Oil Co., Ltd., continued to operate its Naft Khaneh field near the Iranian (Persian) border to supply the local Iraq market through the Rafidain Oil Co., Ltd. Somewhat more than 28 million barrels of crude was produced in Iraq during 1935. Crude delivcred to the pipe line for export during the years 1934 and 1935 was: Year BaRrels 1934................................................. 7,096,669 1935................................................. 27,014,904 Total as at Dec. 31, 193.5.............................. 34,111,573 ° Converted at an avcrage of 7.0 bbl. per ton.

Jan 1, 1936

The principal events during the year consisted in the exploitation of the Kirkuk field, the regular operation of the four-million-ton pipe line to the Mediterranean, and the discovery of low-gravity oil on three other structures in the West Tigris (Shergat) area. The Iraq Petroleum Co., Ltd. continued the systematic exploitation and exploration of its Kirkuk field, maintaining a carefully unitized operation. Bottom-hole pressure differentials and low gas-oil ratios were maintained. All crude was produced by flowing The cleaning up following the construction of the Mediterranean pipe line, which began deliveries in August, 1934, was completed during the first quarter of 1935. The line easily maintained its rated capacity for the remainder of the year. The Mosul Oilfields, Ltd., through its operating subsidiary, the B.O.D., Ltd., expanded its exploratory organization from 9 to 16 drilling rigs and discovercd 20" A.P.I. crude on the Sadid, Hibbarah and Qasab anticlines. Whether these discoveries will be commercial pools remains to be proved. The Qaiyarah-Najmah-Jawan field, which was discovered by the I.P.C. in 1928, was extended arid production was found in the Eo-Cretaceous as well as the "Main Limestone" (Eocene, Oligocene and Lower Miocene). Gas caps were found under each of the crests of the West Tigris structures. Negotiations are in progress between the Mosul Oilfields, Ltd. and the Iraq Government for the extension of the Anatolian Railway from the Turkish border to Mosul, with a view to tanking the heavy West Tigris crude to the Mediterranean. The subsidiary of the Anglo-Iranian Oil Co., Ltd.', the Khanaqin Oil Co., Ltd., continued to operate its Naft Khaneh field near the Iranian (Persian) border to supply the local Iraq market through the Rafidain Oil Co., Ltd. Somewhat more than 28 million barrels of crude was produced in Iraq during 1935. Crude delivcred to the pipe line for export during the years 1934 and 1935 was: Year BaRrels 1934................................................. 7,096,669 1935................................................. 27,014,904 Total as at Dec. 31, 193.5.............................. 34,111,573 ° Converted at an avcrage of 7.0 bbl. per ton.

Jan 1, 1936

By Sidney Powers

Discussion of the paper of SIDNEY POWERS and ALFRED C. LANE, presented at the New York meeting, February, 1916, and printed in Bulletin No. 110, February, 1916, pp. 535 to 548. N. L. BOWEN, Washington, D. C. (communication to the Secretary*). -This detailed study and. complete demonstration of differentiation as a result of the sinking of crystals has a great general significance in petrogenesis. If this action can be demonstrated in an effusive body, even though a very thick one, how can one doubt its possibility in large intrusive bodies? The authors speak of the sinking of augite and the rising of plagioclase but I should consider that they should depend entirely on the former action to obtain their results. It is true that in my experiments, to which the authors refer, a floating of crystals was in one case obtained, viz., in the case of tridymite crystals, but it must be remembered that tridymite has an exceptionally low density. Plagioclase crystals, on the other hand, are of nearly the same density as basaltic liquid. Under magmatic conditions they might be a little heavier than the liquid or a little lighter, we do not know which, but the margin would be exceedingly small and any motion resulting, whether upward or downward, would be correspondingly small in the usual case. For this reason I should think that the sinking of pyroxene should be considered probably the sole factor in producing the observed result, for which purpose it appears to be entirely adequate. The measurements of grain have also a certain significance in this connection. In the experiments referred to a difference of grain was obtained in different parts of the charge, which was entirely independent of the rate of cooling but connected with the fact that a sinking crystal does not depend entirely upon diffusion for the collection of its material from the surrounding liquid. The crystals which sank a considerable distance were therefore exceptionally large. Now in the Cape Spencer flow the augite crystals are normally (top and bottom) somewhat smaller than the plagioclase crystals, but in the layer somewhat below the middle,

Jan 5, 1916

PAUL. D. MERICA, Bayonne, N. J. (written discussion*)..-The mode of intercrystalline oxidation which the authors" have so well observed and described is characteristic of nickel that has been exposed' to: the action of an oxidizing atmosphere at higher temperatures, such as, those at which; it is annealed or heated for rolling or forging. Oxidation under such conditions proceeds inward from the surface along the, crystal boundaries' producing a net-work, probably of oxide; which causes a very brittle condition of this surface material. This, in turn, generally results in surface cracking and checking during further, rolling and a defective sheet or other product is produced. An example of this is shown in Fig. 2, which shows the surface, of a badly surface-cracked sheet of nickel produced by incorrect heating con-ditions. A cross-section of this sheet etched with nitric acid is shown in Fig. 1, which reveals the intercrystalline oxidation network adjacent to both surfaces.These layers are so brittle that it is not possible to deform them by rolling without severe cracking along these lines or, planes of weakness. The best, and possibly only, remedy for this condition lies in its prevention by the maintenance of a neutral soft flame for heating and annealing nickel during the entire course of its manufacture. I should like to suggest that, those making microscopic investigations of nickel and nickel-rich alloys try the use of acetic-acid .solutions of nitric acid for etching these metals rather than aqueous solutions, of nitric acid. I have found that a solution containing 50 per cent. nitric acid, from 25-45 -per. cent. acetic acid, and from 25-5 per cent. water gives excellent results with. Wrought and cast nickel and Morsel metal and superior results to those obtained with nitric acid, alone. The acetic. acid seems to inhibit the passivity that nickel often assumes toward nitric acid and much more uniform etching may, be obtained. The proportions of nitric and acetic, acid may be varied somewhat from those given without mate-rially altering the quality of the etching, although without any distinct improvement in it.

Jan 12, 1919

By C. E. Nelson, T. E. Leontis

THE properties and casting characteristics of sand-cast Mg-Al-Zn alloys, used commercially in this country and abroad, have been discussed in a number of articles during the past few years.'-" In addition, broad surveys of many compositions in the magnesium corner of the Mg-Al-Zn diagram between 0 and 12 pct A1 and 0 and 6 pct Zn have been presented by Busk and Marande7 and by Fox." The purpose of this paper is to furnish a comprehensive survey of the changes in tensile properties, micro-structure, and dimensional stability of two magnesium alloys, AZ92A and AZ63A,+ as a function of aging time and temperature after solution heat treatment. Rates of precipitation in Mg-Al-Zn alloys are slow enough so that a substantially homogeneous, supersaturated solid solution can be maintained even when these alloys are air-cooled from the heat-treating temperature. Consequently, even though it has been demonstrated9 10 that significantly higher strengths can be developed in some alloys in the aged condition by quenching rather than air cooling from the heat-treating temperature, general practice is to air-cool magnesium alloys. All the work discussed in this paper is based, therefore, on aging studies performed on material air-cooled from the heat-treating temperature. This investigation was intended to be a study of commercially practical aging cycles; the tensile properties were determined, therefore, up to aging times of 25-hr duration. The alloys, used in this investigation were prepared in the laboratory by remelting commercial ingots of the appropriate composition according to the procedures described in a previous paper" as the "crucible method." All melts were given the standard superheating treatment in order to insure the maintenance of a uniform grain size of 0.003 to 0.004 in. Standard test bars, 61/2 in. long with a 2½ in. long reduced section having a diameter of Y2 in., were cast from these melts in green-sand molds using a four-bar pattern. The alloys were heat treated according to the following schedules: AZ92A alloy: 500" to 780°F in 2 hr + 780°F (24 hr) AZ63Aalloy: 500" to740°Fin2 hr + 740°F (16hr) In commercial practice," AZ92A alloy is heat treated at 770°F for 18 hr and AZ63A alloy is heat treated at 730°F for 10 hr. The slightly higher temperatures and longer periods of heat treatment were used in order to obtain as homogeneous a solid solution as possible and thus to minimize inconsistencies in the

Jan 1, 1952

By W. F. Hosford

A quantitative explanation is offered for the peculiar curled grain shapes found in the microstructures of drawn wires of bcc metals and compressed aluminum specimens. It is shown that once an [011] fiber texture is developed, the slip system are so oriented that further slip tends to produce plane strain rather than axially symmetric flow of individual grains. With plane -strain flow, however, compatibility of neighboring grains can be maintained only by a bending of grains about one another. PROBABLY the most obvious microstructural feature of heavily worked metals is the distorted shapes of grains. In the course of deformation, the shape change of each grain must be compatible with that of neighboring grains; otherwise holes would be formed at grain boundaries. In analyses of poly-crystalline deformation by Taylor and subsequent workers it was assumed that grain boundary compatability was maintained by each grain undergoing the same shape change as the polycrystalline aggregate in which it is imbedded. According to this assumption, when simple tension or compression is applied to a random polycrystal or to one with a fiber texture, each grain ought to deform with axially symmetric flow. Initially equiaxed grains should become cigar-shaped during wire drawing and pancake-shaped during compression. While microstructural observations of deformed metals are generally in accord with such a picture, certain striking exceptions may be noted. Peck and Thomas5'8 found that grains in heavily drawn tungsten, iron, and niobium (columbium) wires become shaped like ribbons curled about the wire axis, Fig. 1. At a suggestion from the author, they rationalized the development of these micro-structures by considering the orientation of the slip systems in the [011] texture formed by the wire drawing. It is shown in this paper that marked departure from axially symmetric flow of grains is also observed when polycrystalline aluminum is severely compressed. Again the explanation must lie in the orientation of the slip system in the [011] texture, which is formed in fcc metals by compression.' THEORY A simple quantitative argument will be presented to show that the development of these microstructures is a result of flow on the combination of slip systems for which the minimum amount of mechanical work is expended in producing a unit tensile (or compressive) strain. First it must be realized that the macroscopic strains of a crystal resulting from slip are given by: where d dy, and dc, are normal strain increments parallel to the x, y, and z reference axes; are crystallographic shear-strain increments on slip systems

Jan 1, 1964

By Oswald J. Heinrich

THE responsibility resting upon the owners and managers of mines where fire-damp is generated, renders it a matter of imperative duty that a full and correct statement of any explosion that occurs should be given to the public. But such a statement must be based on the testimony of impartial eye-witnesses or trained experts. Then a sad experience may result in the adoption of effective preventive measures. In the absence of any official and professional body of mining experts in the State of Virginia, the writer desires to submit to his professional brethren of the American Institute of Mining Engineers an account of an explosion which recently took place in a colliery under his management, and earnestly desires a thorough and impartial discussion on the facts submitted. Description and Plan of the Mine.-The "Grove" shaft is situated at the nearest point 825 feet from the last old workings upon the Midlothian property, south of the old Pump shaft works. (See Plate III.) The shaft was sunk by the former company, some thirty years ago, to the depth of 622 feet. An incline over 230 feet long, starting in a northwest direction at a depth of 105 feet above the shaft bottom, had been driven to explore the coal on the dip. A return of very small dimensions had been driven round the shaft on the south side, entering the upcast chamber. With the information obtained from the former company that a seam of coal about four feet thick, at a depth of 490 feet, had been found, and with the information obtained by the present proprietor, R. T. Burrows, of Albion, N. Y., by means of two boreholes on the dip west of the old shaft, in both of which workable seams of coal at various depths had been ascertained, the clearing out and thorough retimbering of this shaft were commenced in March, 1873. Borehole No. 1, at a depth of 477 1/2 feet from surface, revealed a seam of coal. This borehole was afterwards carried to a depth of 1140 feet to the granite, without finding any other seam of coal. Borehole No. 3, at a depth of 608 feet, revealed the first coal-seam, 142 feet thick; at 633 feet, the second, 12 feet thick; at 662 feet the third, 1 foot thick, and at 692 feet the fourth, 4 1/2 to 5 feet thick. The borehole was stopped at a depth of 715 1/2 feet.

Jan 1, 1877

By David R. Poirier

Activity data of carbon as a function of both temperature and composition throughout the stable austenite range is correlated by mearts of an equation derived from a quasi-chemical model. The carbon activity data of austmite for temperatures between 800° and 1200°C are utilized in conjunction with the activity of carbon calculated for the y solidus using the activity of carbon in liquid iron and published austenite-liquid equilibria. The results agree very well with Chip-man's correlation; however, a small difference in the activity of carbon in the high-temperature range of the austenite field is evident. Excellent agreement is found for the heat of solution of graphite in infinitely dilute austenite; from this study the value is 10,550 cal as compared with Chipman's value of 10,680 cal. AS part of a program to study microsegregation in dendritic solidification of ternary Fe-C-Cr alloys, it was desirable to be able to describe the equilibria between austenite and liquid iron in Fe-C-Cr alloys. In this regard, it was necessary to correlate existing data on the activity of carbon in Fe-C austenite as a function of both temperature and composition. At that time, Chipman's analysis1 of the thermodynamics of binary Fe-C austenite was not available. It will be shown that this study and Chipman's study agree rather well throughout the stable austenite range of temperature and composition; however, some small differences appear at temperatures greater than the eutectic temperature. Benz and Elliott 2 presented isoactivity lines for austenite superimposed on their revised Fe-C phase diagram. Using an expression from Darken and Gury 3 representing Smith's4 activity data between 800" and 1000°C, they found that the activities extrapolated above 1000°C to the solidus did not agree with the activities determined from the corresponding liquidus compositions. It is the purpose of the following argument to reconcile carbon activity data of austenite with the activity in liquid Fe-C alloys as determined by Rist and Chipman. 5 In addition, a simple analytical expression is sought for computational convenience. ACTIVITY DATA OF CARBON IN ZRON Fig. 1 shows the activity of carbon in Fe-C austenite as determined by Smith, 4 Schenck and Kaiser, 6 Scheil et a1.,7 and Bungardt et al.' The lines are merely drawn to separate the data into the respective isotherms. These data are inadequate to determine the activity of carbon at temperatures greater than 1200°C. The activity coefficient in Fe-C liquid alloys was assumed by Rist and chipmans to obey the following

Jan 1, 1969

ROBERT PEELE, New York, N. Y. (written discussion *).-This excellent paper is one of a number of recent detailed descriptions of the, methods and plant in use at prominent mines of the country. The publication of such papers cannot be too highly praised. In the past, the interchange of inside information has often been hampered by the disinclination of some mining companies to permit publication of details of their work. These companies apparently have not realized fully that free discussion is of mutual benefit; that members of mine staffs are aided in. keeping up to date, in improving old methods and devising new ones to meet changes in conditions, and, by a wholesome feeling of rivalry, are stimulated to introduce economies and do better work. In writing this paper, Messrs. Haight and Tillson have packed a large amount of information into a relatively small space, and the numerous illustrations, chiefly reductions of working drawings, are valuable. The authors are also to be commended for their highly detailed Table of Contents, which adds to the usefulness of the, subject matter. The method of mining at Franklin does not fall readily into any of the accepted classifications. It is a combination of shrinkage stoping and mining of the pillars by a modified top-slicing method. Attention may be called to the fact that, in the wider parts of the orebody, the stopes, 17 to 18 ft. (5.2 to 5.5 m.) wide are transverse; in the narrower parts, they are longitudinal, that is, in the direction of the' strike. This varia-tion is made necessary by the shape and character of the deposit, and distinguishes practice at Franklin from that in some of the western mines. The direction of the stops is changed from transverse to longitudinal when the orebody narrows sufficiently to make the length of a transverse stope approximately equal to its width. Some of the longitudinal stopes exceed 120 ft. (36 m.) in length, and when the hanging wall is bad, requiring prompt filling, three operations' proceed simul-taneously in the same stope, viz., ore is broken at one end, while drawing down goes on in the middle, and filling at the other end. Each transverse stope or chamber is begun by a crosscut from foot to hanging wall, which is afterward enlarged to the stone width and to a height of 12 or 15 ft. (3.7 or 4.6 m.). This preliminary work is done only once for each stope, because the stope is carried up far enough to continue stoping

Jan 1, 1918