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By K. J. Brondyke, P. D. Hess

Lack of correlation between densities of aluminum alloy samples solidified under reduced pressure (vacuum gas test) and hydrogen content of the metal is explained on the basis of inclusions serving as nuclei for hydrogen bubble formation. As a result of these findings, the vacuum gas test is suggested as a practical tool to indicate metal cleanliness and the potential effects of hydrogen. Visual obseroation of the sample during solidification under vacuum provides more useful information than that obtained either from density meas -urements or sectioning of the solidified sample. A rapid, practical method of detecting and measuring gas in molten-aluminum alloys has been sought for many years. The development of the vacuum gas test appeared to solve this problem. However, the vacuum gas test is subject to certain limitations, and the results must be interpreted mindful of these limitations, as described herein. Since the only gas which is appreciably soluble in aluminum is hydrogen, the terms gas and hydrogen will be used interchangeably in this paper. In the early days of the aluminum industry, when techniques were not as refined as they are today, it was customary to pour small "pancakes" of alumi- num on a metal plate. These were allowed to solidify under atmospheric pressure. Excessive gas in the metal was evidenced by the appearance of small bubbles on the surface of the "pancake".' It is obvious that such a method would only show very high gas levels far above any which could be tolerated by today's standards of quality required for most applications. Various attempts were made to develop methods which would be more sensitive. Among these were measurements of density of aluminum alloys solidified under controlled conditions, radiography of cast slabs, and examination of fractures. The method which showed the greatest promise and appeared most practical was the solidification of a sample of the molten aluminum alloy under vacuum. The samples so solidified are evaluated either by observation for bubble emission during solidification, by sectioning the solidified sample and examining for porosity, or by determining the density of the solidified sample. This test is known internationally as the Straube-Pfeiffer test or the reduced-pressure solidification test, but in America it is commonly referred to as the vacuum gas test2-' and will be so designated in this paper. The determination of density appeared an attractive and convenient means of providing a numerical rating for the samples. Attempts were made in some instances to correlate densities to hydrogen contents. Unfortunately, the visible loss of gas during solidification of samples with high gas contents precluded a correlation of vacuum gas test densities with the observed gas evolution. This led to Alcoa's use of two different pressures; 50 mm of

Jan 1, 1964

By M. Van Weyenbergh, G. Van Esbroeck

THE copper mines of the Katanga region in the Belgian Congo lie along the same mineralized belt as those of Northern Rhodesia. There are two distinct types of deposits in that belt, the dolomitic and the quartzitic. In the dolomitic type the metallic minerals are found in a dolomitic limestone country rock. Through oxidation and enrichment,, large deposits of high-grade oxidized copper ores were formed, some of which are being worked by the Union Miniére du Haut Katanga. Such deposits are all in Katanga. The quartzitic deposits are found in Katanga and Northern Rhodesia. Here the primary mineralization occurred in sandstones and quartzites, in horizons stratigraphically lower than the dolomites. These rocks are not favorable to secondary enrichment and the oxidized zone is poorer than the sulphide zone, which alone contains the ore. There are also in Katanga a few ore-bearing veins. One of them is being worked in the Prince Leopold mine at Kipushi. PRINCE LEOPOLD MINE The Kipushi ore body fills a fault vein and invades the wall rocks more or less extensively by metasomatic replacement. The vein strikes north-northeast and south-southwest and dips to the west. The variable dip averages 60ºto a depth of 300 ft., and more uniformly 80º below 400 ft. In the upper section the average width is 200 ft. and below the width is about 150 ft. The length of the ore body is 2300 feet. The eastern side of the vein-the footwall-is dolomitic and contains irregular masses of ore sometimes extending 100 ft. or more from the main

Jan 1, 1939

By Tran K. Van, Francois E. Heuzé, Richard E. Goodman

Sound design of structures founded in or upon rock requires that the deformability of each rock member involved be characterized. This can be done by means of loading tests (plate bearing, flat jacks, borehole jacks, pressure chambers, etc.) or through convergence measurements (tunnel convergence, roof sag, etc.) in exploratory works. Analysis of data will be qualitative (degree of nonlinearity, creep behavior, scattering of results over a number of sites, etc.) and quantitative (modulus of elasticity or deformation). Some of these tests involve a very bulky apparatus and are expensive to perform. On the other hand, for the purpose of mapping and describing the various rock members which occur within a given site, many feet of diamond drill holes are frequently completed. Even with the optimum equipment and expert drillers, however, quantitative characterization of the rock units on the basis of tests on returned samples is apt to be misleading; the softer and weaker components of the rock tend to be lost and the fabric of the rock block- fracture system in situ is not sampled. Laboratory moduli of elasticity have proved to be consistently higher than in-situ values selected for engineering purposes. This led to the design of instruments which would operate in boreholes, combining the advantages of a reduced size and a deeper investigation, from the surface to several tens of feet. BOREHOLE DEFORMABILITY MEASURING INSTRUMENTS In the last 10 to 15 years, a number of testing devices have been con- structed which can be inserted into a borehole to apply a load and mea-

Jan 1, 1972

At the end of June, 1938, a new oil field was opened in Egypt, the Ras Gharib. Five wells were completed during the year and gave a total production of 512,988 barrels.' In the Hurghada field production was as follows: Hurghada Field Age of field to end of 1938, years..................... 25 Producing area for gas and oil, acres................ 1,050 Barrels1 Total oil production to end of 1938............... 31,207,754 Total oil production during 1937................ 1,141,356 Total oil production during 1938.................. 1,019,520 Average oil production per acre to end of 1938... 29,719 Average oil production per acre-foot to end of 1938. . . 243.6 Daily average: production in December 1938.......... 2,603.54 Daily average production per well in December 1938. . 34.90 Millions Cu. Ft. Total gas production (Aug. 1925 to end of 1938)... 4,356.7 Total gas production during 1937.................. 222.5 Total gas production during 1938....... . 167.6 Maximum gas daily average of 1938 (ill May 1..... 0.6 Wells Number of producing wells completed to end of 1938 . . 100 Number of producing wells completed during 1938..... 3 Number of wells abandoned during 1938.............. 2 Producing wells at end of 1938 (all pumping)......... 78 Abandoned wells at end of 1938...................... 22 Dry wells at end of 1938......................... 21 Feet Average depth of bottom of producing horizon........ 1,720 Average depth of top of producing horizonlt 1,598 Character of oil, approximate average ill 1938: specific gravity at 60" F'., 0.900; base, mixed. Character of gas, approximate average for 1938: gallons gasoline per 1000 cu. ft. of gas, 6.4. Main producing formation: Nubian sandstone, Cretaceous (PI; sand rock and sandstone.

Jan 1, 1939

At the end of June, 1938, a new oil field was opened in Egypt, the Ras Gharib. Five wells were completed during the year and gave a total production of 512,988 barrels.' In the Hurghada field production was as follows: Hurghada Field Age of field to end of 1938, years..................... 25 Producing area for gas and oil, acres................ 1,050 Barrels1 Total oil production to end of 1938............... 31,207,754 Total oil production during 1937................ 1,141,356 Total oil production during 1938.................. 1,019,520 Average oil production per acre to end of 1938... 29,719 Average oil production per acre-foot to end of 1938. . . 243.6 Daily average: production in December 1938.......... 2,603.54 Daily average production per well in December 1938. . 34.90 Millions Cu. Ft. Total gas production (Aug. 1925 to end of 1938)... 4,356.7 Total gas production during 1937.................. 222.5 Total gas production during 1938....... . 167.6 Maximum gas daily average of 1938 (ill May 1..... 0.6 Wells Number of producing wells completed to end of 1938 . . 100 Number of producing wells completed during 1938..... 3 Number of wells abandoned during 1938.............. 2 Producing wells at end of 1938 (all pumping)......... 78 Abandoned wells at end of 1938...................... 22 Dry wells at end of 1938......................... 21 Feet Average depth of bottom of producing horizon........ 1,720 Average depth of top of producing horizonlt 1,598 Character of oil, approximate average ill 1938: specific gravity at 60" F'., 0.900; base, mixed. Character of gas, approximate average for 1938: gallons gasoline per 1000 cu. ft. of gas, 6.4. Main producing formation: Nubian sandstone, Cretaceous (PI; sand rock and sandstone.

Jan 1, 1939

By Frank C. Greene

The principal event in the development of oil and gas in Missouri in 1942 was the drilling of the Cities Service Oil Company's No. I Jim Cook, in the northwest corner, NW. 1/4 sec. 32, T. 65 N., R. 39 W., Atchison County, in the northwest corner of Missouri. This well, not yet completed, bailed several barrels of free oil in about 27° Baume from a sand called the Bartlesville by those in charge, at a depth of 1450 ft. The well is on a block of leases obtained after the area, which is covered by several hundred feet of glacial drift, had been prospected by core drilling. Earlier in the year the same company drilled a well on the Glen Gray farm in the southwest corner, SW. 1/4 sec. 29, T. 65 N., R. 39 w., to a depth of 2427 ft. in the Hunton lime with a rotary drill. Oil stains in this hole led to the drilling of the second well. Table i .—-Wells Drilled for Oil and Gas in Missouri in 1942 Country Number of Number of County Oil Wells Gas Wells Dry Andrew.......... Atchison.......... I Bates............ 2 6 Caldwell.......... I 3 Cass............. I Clinton........... I Holt............. I Jackson.......... I I Knox............ I Nodaway......... I Platte............ 4 4 Ray.............. 5 Sullivan.......... I Totals.......... I 7 28 Otherwise drilling in Missouri was uneventful, with a total of only 36 Completions, of which one was a very small oil well, Seven were small gas wells and 28 were dry holes. The total footage drilled was 24,7541/2 ft., of which 14,0281/2 was by cable tools and 10,726 ft. by rotary. Twelve of the dry holes were drilled into Mississip-pian or older beds. Table I gives a summary of activities by counties.

Jan 1, 1943

By Oliver Bowles

THE inorganic non-metallic minerals, that is, the non-metallics exclusive of coal, oil, gas and related minerals, constitute the basic raw materials for a number of essential industries. It is estimated that the value of the raw materials in this group produced in 1919, together with certain of the primary products ordinarily manufactured at the mine, exceeded $800,000,000. They are employed chiefly in the building, agricultural, and chemical industries. It has been estimated, by the Bureau of Mines, that approximately 00,000,000 worth of non-metallic minerals and their products were used in the building trades during 1918; with the great increase in building since that date and the increased cost of materials, the value of non-metals used in such industries during 1920 probably exceeded $500,000,000. The chief of these materials are cement, building stone, crushed stone, sand and gravel, clay products, lime, gypsum, glass materials, slate, talc and soapstone. In many of the producing industries of this great group, the waste is so great that the expense of handling it is an important item in the production cost. The utilization of waste is receiving unusual attention in many of the non-metallic industries at present. The most obvious advantages of such utilization are: (1) Conservation of mineral resources, (2) the removal of waste heaps that in many places obstruct development, (3) manufacture of new and useful products, (4) reduced production costs through elimination of a large part of the item of waste-disposal expense. In many industries there is keen competition between producers of various products used for the same purpose, so that advantage will accrue to the manufacturer who is able to reduce his production costs.

Jan 1, 1921

Statistics compiled by the United States Geological Survey show that the iron ore mined in the United States in 1917 reached a total of 75,288,851 gross tons, exceeding the former record output of 1916 by 121,179 tons. The shipments from the mines in 1917 were 75, 573,181 gross tons, valued at $238,260,333, a decrease in quantity of 2,297,372 tons, or 2.95 per cent., and an increase in value of $56,358,056, or 30.98 per cent., over the shipments in 1916. The average value per ton at the mines for all grades of ore in 1917 was $3.15 as against $2.34 in 1916. Stocks of iron ore at mines, mainly in Minnesota and Michigan, amounted at the close of 1917 to 10,628,908 gross tons, compared with 10,876,352 gross tons in 1916. The quantity of pig iron, exclusive of ferro-alloys, sold or used in 1917, according to reports of producers to the United States Geological Survey, amounted to 38,612,546 gross tons, valued at $1,053,785,975; compared with 39,126,324 gross tons, valued at $663,478,118 in 1916, a decrease of 1.32 per cent. in quantity and an increase of 59 per cent. in value. The average price per ton at furnaces in 1917, as reported to the Survey, was $27.29, compared with $16.96 in 1916, an increase of 61 per cent. The production of pig iron, including ferro-alloys, was 38,647,397 gross tons in 1917, compared with 39,434,797 gross tons in 1916, a decrease of 4.5 per cent., according to figures published by the American Iron and Steel Institute, March 18, 1918.

Jan 12, 1918

Data about production are very meager. In this county from the earliest days until after the Civil War, the amount of coal used locally greatly exceeded that shipped on account of the iron produced; for many years the furnaces used raw coal for melting the ore. In 1846 it was stated that in this county one ton of iron required three tons of iron ore and three tons of local coal used raw.1 In 1864, eleven furnaces in Pennsylvania using 102,230 tons of raw coal produced 44,671 tons of iron, or 2.3 tons raw coal per ton of pig iron .2 This was probably as good a record as was made, as nearly all furnaces changed to coke some years later. Neither of these figures include the coal used for steam and other purposes around an iron plant. The Beaver and Erie Canal was opened in 1845 and the shipments shown from then to 1865, inclusive, are of coal received by the canal at Erie, and do not include any used at local points along the canal. From the completion of the Erie and Pittsburgh Railroad in 1864 the tonnage shipped by canal decreased. rapidly, and, while the canal shipments after 1864 are supposed to be those received at Erie by canal only, they may include some rail tonnages. Tonnages on Erie and Pittsburgh Railroad may, and probably do, include some used locally; those on the Jamestown & Franklin Railroad do not. It is likely that both canal and Erie and Pittsburgh Railroad figures include some coal originating in Lawrence County, and possibly a little from Beaver County. These tonnages are not duplicated in the data for either of the other counties. Not all of the railroad reports can be found now.

Jan 1, 1942

ARTHUR H. STORRS, Scranton, Pa.-I would like to ask whether this same process is applicable to bituminous coal? FELLS A. VOGEL, New York, N. Y.-This Dutch process is applicable to bituminous or any other kind of coal. The Berwind Fuel Co. has had a plant in operation, in Superior, Wis., for about 2 years, using the Dutch process, and it has made a very satisfactory briquette, using Pocahontas coal. There is just one item in Mr. Frey's paper I would like to discuss; that is, the matter of cost. Mr. Frey figures a total cost of $3.35, based on the use of 7 per cent. of oil. Of course, the price of oil has advanced seriously within the last year or two, and any possible reduction in the percentage of oil required in the manufacture of briquettes is very important. I believe that Mr. Frey will agree that very good briquettes can be made with considerably less than 7 per cent. of oil; in fact, actual experience has shown that it can be clone with less than 5 per cent. The only possible effects of a low percentage of oil, particularly in anthracite briquettes, are that the briquette might not burn so freely, and that it might not be quite so hard. Briquettes made by the Lehigh Coal & Navigation Co., using 7 per cent. of binder, are extremely tough. Those briquettes have been handled in one of the local yards in Brooklyn, chuting them from railroad cars into boats and digging them out by grab buckets, and the losses average less than 2 per cent. This compares very favorably with domestic anthracite coal, with which the losses from breakage amount to between 7 and 10 per cent.

Jan 4, 1918

By E. G. Leonardon, C. Schlumberger, M. Schlumberger

The authors give a definition of the various types of corrosion that may affect a metallic conductor buried in the ground, namely: 1. The metallic conductor may be attacked by the surrounding soil. This phenomenon is purely local and is called by them soil corrosiveness. 2. The metallic conductor may connect two regions of the ground when the electrolytes have a different composition. An electrical current will then be generated and certain zones of the conductor will be oxidized. This is autogalvanic corrosion. 3. Stray current may flow in the ground and enter the conductor in certain sections and leave it in others, thus causing oxidization in certain zones; this is electrolytic corrosion. The soil corrosiveness has been studied extensively by the United States Bureau of Standards and the authors give a summary of the work carried out and results obtained along this line. In autogalvanic corrosion it has been shown, by the investigation of buried pipes, that the zones of corrosion are associated with the zones of egress of the electric current (anodic zones). The location of these zones can be determined by measuring at the surface of the ground the difference of potential that exists along the path of the pipe. This work is performed easily and quickly with the apparatus invented by the authors for the exploration of conductive orebodies. The problem of electrolytic corrosion is a difficult one because it is a question of stray current which may vary in direction and intemsity at every instant. Therefore the components of the electrical field must be known at a given station and compared with the components of the clectrical field at another station, at the same moment. This is achieved by a rccording apparatus that will register the variations of the intensity of the electrlc current along two rectangular directions, during several minutes

Jan 1, 1934

J. S. UNGER, ? Pittsburgh, Pa. (written discussion ?).-Firebricks intended for, the same purpose, but supplied by different manufacturers, may be of entirely different clays, contain different proportions of flint, calcined and plastic clays; the particles may vary widely in size; the water used to make the brick will vary; the pressure in molding will vary, depend-ing on whether the brick is hand made or power pressed; and the degree of burning in the same kiln will differ. These variables affect the melting point and the strength of the brick when heated. An important property, of a firebrick is its ability to resist heat and, at the same time, weight or load without serious deformation. The soft-ening point and the melting point of a firebrick may be several hundred degrees apart, and two bricks may show considerable difference in their softening points, but the melting points may be approximately the same. Bricks are not usually employed at temperatures close to their melting points. If they must withstand very high temperatures, the firebrick is discarded and a brick of more refractory material is used. Under these conditions' it is doubtful whether the determination of the melting point of a brick has much practical value. If the determination of the melting point is necessary, the test should he made on a portion of the original brick and not on a specially prepared sample. A small triangular pyramid with a base about 1 1/2 in. and 3 in. high can be sawed from the corner of the brick with a thin-bladed car-borundum wheel, without injuring or destroying the size of particles, the bond, or degree of burning of the original brick. This specimen can then he compared with standard Seger cones or tested by any other method desired.

Jan 12, 1919

By Frank C. Greene

The principal event in the development of oil and gas in Missouri in 1942 was the drilling of the Cities Service Oil Company's No. I Jim Cook, in the northwest corner, NW. 1/4 sec. 32, T. 65 N., R. 39 W., Atchison County, in the northwest corner of Missouri. This well, not yet completed, bailed several barrels of free oil in about 27° Baume from a sand called the Bartlesville by those in charge, at a depth of 1450 ft. The well is on a block of leases obtained after the area, which is covered by several hundred feet of glacial drift, had been prospected by core drilling. Earlier in the year the same company drilled a well on the Glen Gray farm in the southwest corner, SW. 1/4 sec. 29, T. 65 N., R. 39 w., to a depth of 2427 ft. in the Hunton lime with a rotary drill. Oil stains in this hole led to the drilling of the second well. Table i .—-Wells Drilled for Oil and Gas in Missouri in 1942 Country Number of Number of County Oil Wells Gas Wells Dry Andrew.......... Atchison.......... I Bates............ 2 6 Caldwell.......... I 3 Cass............. I Clinton........... I Holt............. I Jackson.......... I I Knox............ I Nodaway......... I Platte............ 4 4 Ray.............. 5 Sullivan.......... I Totals.......... I 7 28 Otherwise drilling in Missouri was uneventful, with a total of only 36 Completions, of which one was a very small oil well, Seven were small gas wells and 28 were dry holes. The total footage drilled was 24,7541/2 ft., of which 14,0281/2 was by cable tools and 10,726 ft. by rotary. Twelve of the dry holes were drilled into Mississip-pian or older beds. Table I gives a summary of activities by counties.

Jan 1, 1943

Striving to do a better job of ad- ministering the letter and spirit of the Federal Coal Mine Health and Safety Act of 1969, the Interior Department recently invited criticism-and got it. The criticisms were voiced on July 1 and 2 at the first of a series of public meetings being held by the Office of Hearings and Appeals at the Department's behest. Later meetings, at which all interested parties are invited to comment, are to be announced in the press and the Federal Register. Persons wishing to participate in the meetings should contact the Director, Office of Hearings and Appeals, 1015 Wilson Blvd., Arlington, Va. 22203. At the first Hearing, USBM Director Elburt F. Osborn outlined the progress his agency has made to date in implementing the law on three fronts: enforcement, education and research. Since the Health and Safety Act became law on December 30. 1969, he said, the Bureau's force of inspectors has grown from a mere 300 to almost 1100, while mine inspections have increased from 10,265 in 1970 to 11,021 for the first six months of 1971. On the educational front. Osborn said, the Bureau now has some 60 instructors who have trained about 50,000 miners in safety procedures since March 30. 1971. Classes at the new Federal Mine Safety Academy for both government and industry personnel begin on September 1, 1971. he added. Health and safety re- search, meanwhile, has been allot- ted $20.1 million for the 1971 Fiscal Year. Of this, $8.1 million is assigned to the Bureau and $12.3 million to contracts with universities and private companies. Admittedly, Osborn said, the mine fatality rate is still unacceptable, hut it was lower in the first half of 1971 than ever before---0.73 per million man hours and 0.31 per million tons of coal.

Jan 1, 1971

By H. S. Fleming

My original intention was to give a full account of Southern furnaces, ores and cokes; but, owing to the difficulty of getting reliable information, I confine this paper to a general description of the ores used in, and immediately around, Chattanooga. Mr. L. S. Colyar, Manager of the Rising Fawn furnace, wrote me in answer to an inquiry as to what ores they were using, " Below I give you analyses of the mixture of ore we have been using for the past seven or eight years. We haven't a complete analysis of any ores, but I will give them to you as I have them. Attalla Soft Rising Fawn Hard Rising Fawn Red Ore. Red Ore. Soft Ore. Iron,.... 50.60 38.48 46.82 Silica,. .. 11.69 7.32 22.69 Phosphorus,. .. 1.06 .319 .350 This is a fair average of all the ores we get in this section." The following analyses of Birmingham soft ore were received from the Morris Mining Co., of that place. No. 1. NO. 2. No. 3. No. 4. Iron.....51.60 54.88 51.04 51.20 Silica,. .. 19.32 10.60 17.32 17.08 Alumina,....19 .88 1.18 Phosphorus,. ..129 .287 .116 .464 Mine No. 1, second vein, shows: iron, 46.40; alumina, 4.92; phosphorus,.212; silica, 19.60. Mine No. 1, by analyses obtained from the Mary Pratt Furnace CO., shows: Iron. Silica. Fine red ore,.49.00 18.38 Lump red ore,...54.42 17.10 Bottom vein,.50.00 21.38 Bottom vein,.41.24 13.52 A lot of this ore delivered in Chattanooga gave : iron, 53.32; alumina, 2.10; phosphorus,.529; silica, 18.03.

Jan 1, 1887

By T. B. Counselman

PROBABLY the earliest concentration of iron ore in this country was carried on in the northeastern magnetite areas. Magnetic concentration was relatively simple and gave a concentrate that, after agglomeration, and in spite of being high in phosphorus because of the dry concentrating methods then in use, was satisfactory blast-furnace feed. Production from the northeastern magnetite area languished after the discovery and development of the Lake Superior ores, where there was seemingly an unlimited tonnage of high-grade ore, first the Michigan ores, and subsequently the still larger deposits of Minnesota. For years only the higher grade, direct shipping ores of the Lake Superior district were mined. Those of Michigan, and of the Vermilion Range in Minnesota, were hard ores and came principally from underground mines. The softer ores of the Mesabi came partly from underground mines, but mostly from the enormous deposits that could be worked by open-pit methods. The costs of ore from these open-pit deposits, even with the high initial cost of stripping, were so low that the underground mines of the Mesabi could hardly compete. The so-called Old Range ores, of Michigan and of the Vermilion Range of Minnesota, were hard and lumpy, and opened up the burden in the blast furnace, therefore making possible harder driving with greater output. Also, some of these ores were of such grade and physical characteristics that they were suitable for charge ore in the open hearth. These ores, therefore, commanded a price premium, and could compete with the softer, finer, but cheaper, Mesabi ores. The big tonnage reserves, however, are on the Mesabi, and it is these big open-pit deposits that constitute our stock pile of iron ore, from which we are drawing so heavily during this war period. On the western end of the Mesabi the ore was found to be high in silica, and not suitable as furnace feed. As early as 1902, attempts were made to concentrate this so-called wash ore and by 1910 the first washing plant was put into operation. The process was very simple, consisting essentially of a sizing and washing operation, with scalping screens, logwashers, and tables, which later were replaced by classifiers. Ore particles finer than 100 mesh were deliberately wasted, because these fines were undesirable in the furnace. Fortunately, these tailings were impounded, and already are being reworked. Before long some of the low-grade ores began to require more elaborate treatment than the simple washing operation and, tables having been discarded because of their low capacity, in favor of classifiers, jigs were next introduced. These were able to discard coarser pieces of tailing than classifiers. Jigs are in active use today, various improvements having been made in their design and application. Various other machines and methods of concentration have been tried from time to time, and have in turn been discarded for more improved processes. The latest and most important process that has been

Jan 1, 1943

By L. E. Young

The purpose of this paper is to start a discussion on: (I) methods of supporting the immediate roof, particularly of local areas of poor roof, during the mechanical loading of coal; (2) methods of increasing the rapidity of the movement of the mining faces so that, without the use of cribs, jacks, park walls, and filling, there will be no danger to men, equipment, and working places from the subsidence of the overlying strata. In the Pittsburgh district the application of mechanical loading devices in mines working in the Pittsburgh seam has been retarded by the difficulties of holding and handling the draw slate. Normally the thickness of this slate averages about 8 in. but the hardness varies, and a cut of coal cannot always be loaded without placing posts or crossbars to support the slate. Locally, the slate may be thicker and special methods of support may be required. If crossbars are placed to hold the slate when the coal averages 5 ft. in thickness, the standard methods of transporting the coal cannot be followed, and the use of conveyors may be desirable. Very little information is available on the effect of increasing the rate of movement of advancing or retreating break lines or longwall faces. A few British publications have presented some data but all such data relate to longwall faces that have moved not more than 6 ft. a day. The most rapid rate of movemerit of longwall faces in Germany is 6 ft. per day. In the ordinary hand-loading mine in western Pennsylvania break lines on full retreat will move about 2 ft. per day. If loading machines are used under similar conditions the rate of retreat may reach 4 ft. per day. In a mine where coal is loaded by hand on conveyors three shifts per day, the rate of retreat has ranged from 11 to 16 ft. per day, with an average of 13 ft. If mobile loading machines could be used to load on conveyors on break lines, the rate of retreat should be increased substantially During 1935 and 1936, the United States Bureau of Mines, under a cooperative agreement with the Pittsburgh Coal Co., carried on studies of roof movement at Montour To. 10 mine. The work war done urider the direction of Mr. H. P. Greenwald, Supervising En neer, Experi-

Jan 1, 1938

By L. E. Young

The purpose of this paper is to start a discussion on: (I) methods of supporting the immediate roof, particularly of local areas of poor roof, during the mechanical loading of coal; (2) methods of increasing the rapidity of the movement of the mining faces so that, without the use of cribs, jacks, park walls, and filling, there will be no danger to men, equipment, and working places from the subsidence of the overlying strata. In the Pittsburgh district the application of mechanical loading devices in mines working in the Pittsburgh seam has been retarded by the difficulties of holding and handling the draw slate. Normally the thickness of this slate averages about 8 in. but the hardness varies, and a cut of coal cannot always be loaded without placing posts or crossbars to support the slate. Locally, the slate may be thicker and special methods of support may be required. If crossbars are placed to hold the slate when the coal averages 5 ft. in thickness, the standard methods of transporting the coal cannot be followed, and the use of conveyors may be desirable. Very little information is available on the effect of increasing the rate of movement of advancing or retreating break lines or longwall faces. A few British publications have presented some data but all such data relate to longwall faces that have moved not more than 6 ft. a day. The most rapid rate of movemerit of longwall faces in Germany is 6 ft. per day. In the ordinary hand-loading mine in western Pennsylvania break lines on full retreat will move about 2 ft. per day. If loading machines are used under similar conditions the rate of retreat may reach 4 ft. per day. In a mine where coal is loaded by hand on conveyors three shifts per day, the rate of retreat has ranged from 11 to 16 ft. per day, with an average of 13 ft. If mobile loading machines could be used to load on conveyors on break lines, the rate of retreat should be increased substantially During 1935 and 1936, the United States Bureau of Mines, under a cooperative agreement with the Pittsburgh Coal Co., carried on studies of roof movement at Montour To. 10 mine. The work war done urider the direction of Mr. H. P. Greenwald, Supervising En neer, Experi-

Jan 1, 1938

By E. B. Harden, J. H. Harden

The practical use to which topographical models or relief-maps have been put, has within the last few years taken a wider range. They are rapidly coming into favor for other than purely scientific purposes, and their value for illustration and instruction is being more fully appreciated. Topographical maps; representing by contour-curve lines the elevations and depressions of the earth's surface, are now demanded in engineering work of nearly every description, and afford a ready means of bringing out the configuration of the country in a simple manner. A beautiful example of recent topographical mapping is seen in the seventeen sheets just issued by the Geological Survey of New Jersey. By reason of the inability of unskilled persons to understand the nature of a topographical map, it is sometimes necessary to con struct the same in relief, with the rivers, canals, railroads, etc., delin eated upon it. With the aid of such a map, problems in engineer ing science which would otherwise require expert assistance to explain them, are reduced to a simple and understandable form. Relief-maps are also of value to the geologist in working out the geological structure. To the instructor they present the most ready and efficient means of imparting clear and accurate knowledge of topography and kindred subjects. To the lawyer they are invalua ble in enabling him to bring into the court-room a representation of a part of the country with all its features accurately shown, to ex plain to the court and jury the special points about which litigation is pending and which would otherwise require long and laborious description. The application of the topographical map to business purposes is shown in a relief constructed by the writers for the Cumberland Valley Railroad Company and used by that company in the various ways of calling attention to the desirability of its route. This model is based partly on actual survey and partly on sketch topography. The horizontal scale is ,%, the vertical 1/19,200 of

Jan 1, 1888

By Francis Crockard

DURING the past five years we have probably witnessed greater technological advances than in any similar period. Industry and science have steadily marched ahead. The makers of iron and steel products have watched with great interest the development of stream-lined trains, faster and safer airplanes, the entirely new science of air-conditioning and the widespread use of stainless steels. Since 1930, we have witnessed the erection of the world's largest suspension bridge, the largest and fastest ocean liner and the spectacular Boulder Dam, while even greater things are planned in these particular fields. Other indus-tries, too, have been moving ahead rapidly. This advance in a few years has been caused primarily by the fierce competition of the depression. Now, more than ever, is the emphasis placed upon quality and service. Makers of southern merchant pig iron have been no exception and have been confronted with increasingly strict chemical specifications and with much greater stress on physical characteristics than ever before. For example, sulfur in the iron must be held very low, competition demanding that it be in the 0.020's and low 0.030's; silicon content must be held within a very narrow range, and definite requirements of phos-phorus and manganese are an essential part of the specifications. Physical characteristics are becoming of increasingly greater impor-tance. The introduction of triple-skimmed, slow-cooled iron several years ago was the first step in this direction. Now there are a few customers who buy iron by chemical analysis and physical appear-ance, having found that the analysis alone is an insufficient guide to their requirements.

Jan 1, 1936