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By Eugene H. Cowles

Now that a determined public effort is being made on this side of the Atlantic to create a steel ship-building industry, the materials that are demanded for this purpose assume a new interest to the American metallurgist. In the past, the uses of metals in this country have been almost exclusively connected with the land, while in England their application to marine purposes has been equal in importance to that on shore. In the future the same should be the case here. This is the reason for bringing a somewhat nautical or rather naval topic before a body the chief interests of which are supposed to lie in the mines and mountains of the interior of the country. A modern war-ship or " ocean-grayhound" (like the City of Paris) is an epitome of philosophy and human skill. In her graceful lines we have, as Ruskin might quaintly say, a " builded geometry ;" while in her wonderful machinery for motion, offensive and defensive, we have the summation of the ideas of a host of students who have, at one time or another, during the course of a hundred years of her evolution, contributed their intellectual mites to render her a thing of beauty and of power. Notwithstanding her present perfection, the modern ship contains room for further improvement. One of the most important things about her is the propeller. This active member is of more impor-

Jan 1, 1890

By George T. Wickes

Several years ago, Mr. Robert A. Cook described and illustrated in our Transactions a mechanical coke-drawer, patented in 1891 by Mr. Thomas Smith of the Thorncliff Iron Works, Sheffield, England, and first introduced in the United States in 1896, at the coking-plant of the Latrobe Coal Co., Latrobe,Pa. This machine has not received any very extended application in this country, although it was successfully used in two places for a number of years. The present paper describes a new and simpler machine, containing few wearing-parts, and capable of withstanding continued rough usage. Anything which tends to prolong the general use of bee-hive ovens will be welcome to those who are interested in cheapening the cost of producing coke in such ovens, especially if it provides satisfactory mechanical means, replacing the hard labor involved in drawing coke by hand with the old-fashioned " duck bill." The difficulty of finding efficient coke-drawers, especially during the summer season, and in the South, is notorious. Yet, notwithstanding the great improvements that have

Jan 1, 1906

By Basil B. Zavoico

Production of crude oil in the U.S.S.R. during 1940 is estimated at 222,600,000 bbl., as compared with the revised figure for the preceding year of 220,866,000 bbl., an increase of 0.79 per cent, and at least 20 per cent under the planned output. Baku district (Transcaucasus) remained the outstanding producing area, accounting for 72.33 per cent of the country's production, and this relative importance of the Apsheron Peninsula oil fields will probably continue lor many years to come. In the North Caucasus the Grozny-Dagestan area further extended its decline and the current production in this district amounts to only 6.06 Per cent Of the total U.S.S.R. output, as compared with 35.76 Per cent in 1931 The production of the Kuban-Maikop district remained virtually ullchanged from the preceding year, amounting to 7.64 per cent of the country's total. The Caucasian Province, therefore, in I940 produced 86.03 Per cent of the total production of the U.S.S.R. The promising new Permian Basin district, called Ural-Volga, and referred to sometimes as the "Second Baku," increased its production appreciably during 1940 and the output of that area amounted to 8.31 per cent of the country's total, as compared with 6.35 per cent during 1939. Production in the secondary districts of Russia continued unchanged though some new discoveries in the Emba salt-dome basin suggest that the output of that district may show some increase during the coming years. The drilling operations in Russia during 1940 reached a stage of virtual breakdown and the original footage plans were fulfilled only to the extent of around 50 per cent, while exploration drilling schedules were fulfilled only to the extent of about 25 to 35 per cent. This condition was due to the obvious lack of modern drilling rigs, of good drill pipe and of strong casing. Extended breakdowns occurred with deeper drilling, particularly because with few good drilling rigs available speed was being attempted with rotation rates that the inferior drill pipe and bits could not stand. Twistoffs and endless fishing jobs resulted. The difficulties became so serious a handicap to the Soviet oil industry that it was found imperative to order American drilling equipment and pipe in quantity, a policy that was never favored in the U.S.S.R because it requires expenditure of gold or exchange in major volume, and such exchange usually is reserved only to less bulky key items or to orders directly connected with armaments; also, oil-field machinery is very bulky and the prevailing lack of bottoms makes the transport of the indicated equipment a major problem. But little progress was similarly made in other branches of the Soviet oil industry. NO new major pipe-line construction work was undertaken, consequently the railroads continued to be overburdened with traffic that could be much more effectively handled by pipe lines. No new refinery construction of any magnitude was initiated, though several plants that had been in course of construction for several years were completed during 1940 and operation 554

Jan 1, 1941

By Basil B. Zavoico

Production of crude oil in the U.S.S.R. during 1940 is estimated at 222,600,000 bbl., as compared with the revised figure for the preceding year of 220,866,000 bbl., an increase of 0.79 per cent, and at least 20 per cent under the planned output. Baku district (Transcaucasus) remained the outstanding producing area, accounting for 72.33 per cent of the country's production, and this relative importance of the Apsheron Peninsula oil fields will probably continue lor many years to come. In the North Caucasus the Grozny-Dagestan area further extended its decline and the current production in this district amounts to only 6.06 Per cent Of the total U.S.S.R. output, as compared with 35.76 Per cent in 1931 The production of the Kuban-Maikop district remained virtually ullchanged from the preceding year, amounting to 7.64 per cent of the country's total. The Caucasian Province, therefore, in I940 produced 86.03 Per cent of the total production of the U.S.S.R. The promising new Permian Basin district, called Ural-Volga, and referred to sometimes as the "Second Baku," increased its production appreciably during 1940 and the output of that area amounted to 8.31 per cent of the country's total, as compared with 6.35 per cent during 1939. Production in the secondary districts of Russia continued unchanged though some new discoveries in the Emba salt-dome basin suggest that the output of that district may show some increase during the coming years. The drilling operations in Russia during 1940 reached a stage of virtual breakdown and the original footage plans were fulfilled only to the extent of around 50 per cent, while exploration drilling schedules were fulfilled only to the extent of about 25 to 35 per cent. This condition was due to the obvious lack of modern drilling rigs, of good drill pipe and of strong casing. Extended breakdowns occurred with deeper drilling, particularly because with few good drilling rigs available speed was being attempted with rotation rates that the inferior drill pipe and bits could not stand. Twistoffs and endless fishing jobs resulted. The difficulties became so serious a handicap to the Soviet oil industry that it was found imperative to order American drilling equipment and pipe in quantity, a policy that was never favored in the U.S.S.R because it requires expenditure of gold or exchange in major volume, and such exchange usually is reserved only to less bulky key items or to orders directly connected with armaments; also, oil-field machinery is very bulky and the prevailing lack of bottoms makes the transport of the indicated equipment a major problem. But little progress was similarly made in other branches of the Soviet oil industry. NO new major pipe-line construction work was undertaken, consequently the railroads continued to be overburdened with traffic that could be much more effectively handled by pipe lines. No new refinery construction of any magnitude was initiated, though several plants that had been in course of construction for several years were completed during 1940 and operation 554

Jan 1, 1941

By R. V. Ramani, R. M. Mishra, Y. J. Wang

The validity of the concept of mine resistance in ventilation systems is examined. Mine resistance is the proportionality constant relating the head generated by a fan and the quantity flowing through it when the fan is connected to a mine circuit. It is the total effect of all branches in the mine ventilation circuit. Its importance lies in the fact that for new mine projections, and in the extensions of existing mines, ventilation calculations are usually based upon adjustments of the mine resistance. In ventilation circuits with regulation, and/or with multi-fans, simple adjustments of the mine resistance curve do not lead to correct solution. A ventilation system consists of several interconnected subsystems where one subsystem behavior affects that of the others, and the total system. Through a series of simple but realistic examples, the authors demonstrate the importance of the systems concept in mine ventilation, and its practical application to coal mine ventilation planning. Starting from an initial system with no leakage and one fan, more complex ventilation networks with several leakages, sections and fans, are analyzed to show that ventilation system design on the basis of total systems approach is the correct procedure.

Jan 1, 1979

By H. F. Miller

Fox some years the prejudice against basic open-hearth steel for casting has been gradually decreasing. Yet many consumers and engineers still cling to acid steel for castings, because of their alleged greater freedom from blow-holes and sponginess. Acid steel has been used for this purpose much longer than basic steel; and the melters in acid practice had it well in hand when basic steel was first tried. Then the necessity of learning a new set of laws for the production of satisfactory basic open-hearth steel for castings became evident. The first of these laws, in my opinion, has to do with the furnace construction. The heat should be melted down as speedily as possible so as to prevent excessive oxidation. I have described in another article ' some furnaces designed by me, and having as one of their features the promotion of quick melting. Size of the Furnace. The hearth of the furnace, however, is a decisive factor in the production of solid castings. The manufacturer should know the size of the heats he intends to make constantly, and should have his furnace built for that size of heat. The hearth should differ in dimensions from that of a furnace making ingotr steel. That is, the bath should be deeper and should have less surface-area. A shallow bath permits the slag to come out soon after the steel commences to flow, and thus prevents the additions from going into the steel, or from becoming uniformly distributed in case they have been put in hurriedly. Under this head comes the very poor practice of making small heats in hearths of a much larger capacity. If into a 25-or 30-ton furnace only 12 or 15 tons of metal is charged per heat, the proportion of heats that will be wild, or show signs

Jan 1, 1913

THE gold medal of the Mining and Metallurgical Society of America was presented, on Jan. 10, 1922, to Charles Warren Goodale, "for signal services in furthering the welfare and safety of workers in the mining and metallurigical industries of America." The presentation was made by Dr. J. E. Spurr, presi-dent of the Society for the year 1921, at the annual meeting held in New York City. Dr. Van H. Manning, formerly director of the U. S. Bureau of Mines, made the first address. Toward the close of his brief speech, he said, "It has happily been suggested, ?Let us balance our praise of war heroes by pausing to honor a hero of peace.' We have with us tonight a man who has been a leader and inspirer of thousands of his contemporaries. . . . His zeal in the great work of increasing the safety of men engaged in mining and metallurgical operations has become an obsession with him. . . . That lie has been success-ful is evidenced by the great work, of which I have personal and intimate knowledge, done by him in con-nection with the Anaconda Copper Mining Co. and its subsidiaries." Dr. J. F. Kemp gave a brief sketch of Mr. Goodale's career, in the course of which he said, in speaking of .the consolidation of the Boston and Montana, the Anaconda, and smaller companies, "at the same time electric current was introduced for haulage in the mines and on the surface for the running of air compressors and the hoisting of the cage. . . . We can see that there was great danger to the miner and that safety first became a very important feature of the work. . . .

Jan 2, 1922

By W. E. D. Jr. Stokes

THE application of aviation to mining and petroleum operations, on the basis of economy and attainment, has become a demonstrated fact. According to Dominion Government records, 30 Canadian companies engaged in air transportation with northland mining camps, carried 13,000 tons of freight in 1935, and in 1936 carried 16,000 tons. In addition, many mining companies used planes to transport prospectors with canoes, outboard motors, gasoline drums and supplies to remote locations, and one company maintained a plane to take radium-bearing ore from its mine on Great Bear Lake nearly 1000 miles south to the rail-way at Waterways, Alberta. Heavy pieces of mining machinery weighing 2 tons are being carried by Ford trimotor planes over the Andes, at an altitude of not less than 15,000 feet. At Bulolo, New Guinea, 17,500 tons of disassembled gold-dredging equipment has been flown over inaccessible terrain, while supplies and building materials for a community of 1000 whites have been transported by airplane. A 31 z-ton shaft was carried on one notable trip, while at another time an automobile, 2 tons of rice and a large safe went over the mountains in one plane. Fig. 1 shows an electric generator that was carried by plane to Bulolo. Many large American oil companies operated fleets of planes during 1936, ranging from fast, luxurious air liners for executives to elaborate geological prospecting units, ambulance planes, freight carriers and pipe-line repair crews.

Jan 1, 1937

By Dale S. Preece

INTRODUCTION In 1975 Congress passed the Energy Conservation Act to establish a U. S. Strategic Petroleum Reserve (SPR) with a capacity of 750 million barrels of crude oil. The most economic storage medium was determined to be salt caverns leached in salt domes in Louisiana and Texas. Salt caverns existed at several sites when the reserve was created. These were obtained by the U. S. Department of Energy (DOE) and used to initiate SPR oil storage. In order to meet the storage capacity approved by Congress, new caverns also had to be leached. To support the resulting design effort, finite element computer programs have been used to determine the creep closure and structural stability of salt caverns Using site specific material properties including creep models, elastic moduli and fracture data, the finite element analyses have replaced earlier empirical approaches to cavern design. This report presents results of such finite element analyses to determine the best cavern roof shape and the minimum pillar to diameter ratio, P/D. These numerical predictions indicate that the current cavern design is safe. FINITE ELEMENT AND MATERIAL MODELING The finite element program used in this study has existed for approximately four years. Its theoritical basis (Key, et al, 1980) and application are well documented It was originally developed to predict the creep around mined openings In bedded rock salt for the Waste Isolation Pilot Plant (WIPP) The program was tested by modeling the creep of salt around a drift and by comparing the results with the predictions of eight other structural computer codes (Morgan, et al, 1981) Since then the program has had continual use for calculations to support the WIPP (Miller, et al, 1982) For about two years the

Jan 1, 1984

By G. C. Gester

With the exception of exploration geological work that is being prosecuted in various parts of the mainland of Arabia, the only new developments in Arabia during 1934 were on Bahrein Island, which is in the southwestern portion of the Persian Gulf, approximately 25 miles from the mainland of Arabia. Here the Standard Oil Co. of California, through its wholly owned subsidiary, The Bahrein Petroleum Co., Limited, has continued to carry on a systematic drilling campaign and has constructed camps, pipe line and marine loading facilities. During 1934 eight wells have been completed at depths ranging from 2058 to 2253 ft. These wells have shown average initial productions ranging from 1500 to 5000 bbl., with one, No. 15, estimated as being capable of flowing as much as 11,000 bbl. per day. The oil is asphaltic in character and has a gravity range of from 32' to 34' A.P.I. The locating of all new wells has followed a plan of orderly development, with the ultimate object of obtaining efficiency of operation and maximum production. The wells are taking a penetration of 200 to 250 ft. of the lower or so-called Main productive zone. The upper oil zone, which is cased off, includes 300 to 400 ft. of alternating limestones, clays and shales and carries a heavier oil under lower pressures. The Main zone is similar lithologically to the upper zone. Micro-fauna collected from cores have shown that the oil occurs in formations of lower Eocene and Cretaceous age. Development to date has not progressed sufficiently so that either the maximum thickness of the oil-bearing horizons or the limits of the field can be determined. Something over 10,000 acres has been proven to date. Among other developments leading toward the marketing of oil from Bahrein during 1934 was the construction of a marine loading terminal. This included the laying of over 3 miles of 12-in. submarine pipe line from the small island of Sitra out into the harbor, terminating in 50 ft. of water; also the laying of more than 10 miles of gathering lines from the producing area to the terminal. Three crude oil working tanks with floating roofs were erected on Sitra Island, having a capacity of 250,000 bbl. A pumping plant was provided having a capacity of 5700 bbl. of oil per hour. This is housed in a dustproof building, as rather severe

Jan 1, 1935

By T. V. Falkie, Robert Stefanko

Much criticism has been directed at the Coal Mine Health and Safety Act of 1969 from many sources, but few specific charges have been leveled, at least publicly. Yet, if the criticism is truly valid and can ever hope to become constructive, the issues must be approached head on. Therefore, the authors consider this an initial article and invite responses from others for contributions in subsequent issues. Dialogue is today's popular term and perhaps many of the problems associated with the implementation of the Act are the lack of communication between interested parties. There are two criticisms generally made concerning the philosophical approaches taken in the Act. The first is that there is an over-kill in some of the legislation, some provisions are not justified based on past accident history and economic considerations. Generally speaking in this category, no order of priority was considered consistent with safety and economy. The second category includes those situations where new provisions were imposed to improve safety in one area without adequately considering the consequences in another area, let alone the economics of the situation. While the authors do not always agree with the placement of items in these two categories by some industrial representatives, they will give specific examples that they believe may have a certain degree of validity.

Jan 1, 1971

By Horace Pops, L. L. Isaacs

SOLID-STATE transformations at low temperatures are frequently studied by optical metallography. Greninger and ooradian' and Hull and Gar-wood2 have examined the martensitic-type transformations in 0-phase Cu-Zn alloys during continuous cooling below room temperature. The lowest range of temperatures in the apparatus described by these investigators is limited to approximately 110°K. Present studies of reversible first-order phase transitions near liquid-helium temperatures have necessitated the design of a new cold-stage cryo-stat for optical metallography. The features of interest of this instrument are as follows: a) temperatures down to 4.Z°K are obtainable; b) the specimen is always under vacuum, thereby avoiding the condensation of moisture; c) specimens can be rapidly cooled or heated at varying rates, thus permitting studies of transformation hysteresis. Fig. 1 shows the details of the cryostat. All major parts are made of type 304 stainless steel. Both helium and nitrogen cans are Heliarc-welded to the helium filling tube, permitting the use of a common shielding can. Hence, the over-all weight and the area of the evacuated surface are mini- mized. The copper sample holder is screwed into the bottom of the helium can. To assure good thermal contact between the sample holder and the refrigerant, an indium ribbon is placed on the threads

Jan 1, 1964

By Georges Millot

USUALLY the search for clays is left to chance in unexplored areas. A local working by the inhabitants or an outcrop is often the only guide. If the conditions of genesis of clays were always known, a set of general rules could be drawn up that would apply to this search. For example, a certain type of clay might be found wherever the sediment indicated a favorable environment. This paper sums up the considerable amount of knowledge that has been accumulated about the genesis of sedimentary days and offers some rules to be observed in prospecting for new clays. ANALYTICAL STUDY OF SEDIMENTARY CLAYS Clays may be found in many formations, both recent and ancient. All the intermediums exist between the deep-sea deposit and the mud deposited by a stream. In order to find out whether the nature of clay deposits depends on the environments in which they were formed, the samples used in the investigation described herein were very carefully chosen from: (1) ancient sedimentary series (a few from recent ones), (2) zones where conditions of genesis are typical. Ancient Formations Ancient formations were chosen because they are less difficult to sample than the bottom sediments of present-day lakes and seas. Moreover, a geo- logical section makes it possible to define the conditions of genesis of a deposit based on its facies, fossils, stratigraphic relations, and paleography. A present-day deposit is defined only by its aspect at the moment. Its previous history may have caused mixtures, alterations, and changes of environment, which escape detection. Typical Conditions of Genesis Samples from ancient deposits were taken from zones where typical conditions of genesis prevailed. Only clays from marine, lagoonal, and lacustrine environs are concerned in this study because the nature of the original en- vironments could be affirmed. In this way an inventory of the nature of sedimentary clays has been made for rocks formed in typical and individual environments; therefore the extent of the results that may be drawn from such a study will need discussion.

Jan 1, 1952

The following specifications, proposed by a sub-committee of the American Society for Testing Materials, are still to be adopted and subsequently submitted to the International Association for Testing Materials. Standard Specifications for Pig-Iron and Castings. I. Analysis.—It is recommended that all purchases be made by analysis. II. Sampling.—In contracts where pig-iron is sold by chemical analysis, each carload, or its equivalent, shall be considered as a unit. At least one pig shall be selected at random from each two tons of every carload, and so as to fairly represent it. Drillings shall be taken so as to fairly represent the fracture surface of each pig, and the sample analyzed shall consist of an equal quantity of drillings from each pig, well mixed and ground before analysis. III. Allowances and Penalties.—III all contracts, in the absence of a definite understanding to the contrary, a variation of 10 per cent. of silicon, either way, and of .01 in sulphur above the standard is allowed. A deficiency of over 10 per cent. in the silicon, up to 20 per cent., and a further increase in sulphur up to .01 over the above allowance subjects the shipment to a penalty of 1 per cent. in the price for each element so affected. IV. Base Analysis OF Grades. —In the absence of specifications the following numbers, known to the trade, shall represent the appended analyses for standard grades of foundry pig-iron, irrespective of the fracture, and subject to allowances and penalties as above. Silicon Sulphur Grade. Per Cent. Per Cent. No. 1,...2.75 0.035 No. 2,.2.25 0.045 No. 3,........1.75 0.055 No. 4,.1.25 0.066 Cast-Iron Pipe and Special Castings. I. Description of Pipes.—The pipes shall be made with hub- and spigot-joints, and shall accurately conform to the dimensions given in Tables Nos. I. and 11. They shall be straight and shall be true circles in section, with their inner and outer surfaces concentric, and shall be of the specified dimeneions in outside diameter. They shall be at least 12 feet in length, exclusive of socket. For pipes of each size from 4-inch to 24-inch, inclusive, there shall be two standards of outside diameter, and for pipes from 30-inch to 60-inch, inclusive, there shall be four standards of outside diameter, as shown by Table No. 11.

Jan 1, 1905

By Howard Talbot

THE history of the development of the strip in- dustry, mentioned in this paper, was covered in considerable detail by Stephen Badlam in his paper presented. before the American Iron and Steel Institute at its meeting in New York last October. The description of progress in rolling strip there out-lined will be found good reading by anyone interested in the subject. Quoting from Mr. Badlam's paper, "For practically thirty years, we find no record of the use of the backing-roll principle, until in 1916 the Lukens Steel Co., Coatesville, Pa., put in a 206-in. plate mill of the four-high type. This was a reversing mill with two 32-in. working rolls and two 50-in. backing rolls and is today making the widest and heaviest plate made anywhere in the world." The functioning of this mill, though rolling hot plate, is, on account of the extreme width and thinness of plate rolled, quite comparable to the rolling of wide strip either hot or cold and was a considerable factor in demonstrating the marked advantages available with the four-high or backing-roll mill for thin accurate rolling. As the writer has brought out, a demand for a product, the rolling of which required the character-istics of the backing-roll mill, was broached by the In-ternational Nickel Co. This resulted in an inquiry of March, 1924, for the building of a mill capable of cold-rolling wide nickel and monel metal sheets or strip, as mentioned. It may be of some interest to note, that whereas the .six-roll cluster mill with plain bearings was built for this installation, the mill designed by the United En-gineering and Foundry Co. for this inquiry was of the four-high type with roller bearings on the backing-roll necks, being essentially the same design as the four-high roller-bearing mill built in 1925 for the Rome Brass & Copper Co. This Rome mill, to quote again from Mr. Badlam's paper, "fulfilled every requirement, and was the model on which succeeding mills of this type were built."

Jan 5, 1928

By Arthur B. Foote

The cams at present universally used in stamp mills lift the tappets with an involute form of curve, to which the surface of the tappet is always tangent; moreover, the line of contact between tappet and cam, if produced, would pass through the center of the stem. This is no doubt a desirable feature, but the writer has long believed that it would be much more desirable if the cam were to pick up the stamp without shock, and gradually increase the upward velocity of the stamp throughout its upward movement. The involute form of cam attempts to impart instantly a considerable upward velocity to the stamp, starting it from a state of rest, and the result is a destructive blow, a great deal of noise, and much wear and vibration. The writer has developed a form of cam which will lift the stamp pith a motion similar to that of the piston of an engine between the end and middle of its stroke; in other words, harmonic motion, from the woint of zero to maximum velocity. The curve will give this ideal motion only when the stamp is set for the exact drop for which the cam was designed, but the improved cam will not be as bad as the involute cam until the drop is reduced one-half. In other words, if a cam is designed for a 6-in. drop, it will be some improvement over the usual form of cam until the drop is only 3 in. Any cam, whatever its form, must of course lift the stamp in the same number of degrees of revolution; therefore, with this new form, since the stamp starts more slowly on its upward course, it must end up by going faster, the average speed being the same as with the involute cam. The stamp, after it is no longer in contact with the cam, keeps on going up a certain distance, which is easily calculated. It is therefore possible to hang up a stamp without a cam stick, if the fingers are not more than + in. longer than necessary to hold the tappet above, the cam. With this design of cam the surface of the tappet is not tangent to the surface of the cam throughout the lift. The possible consequences of this were studied with a full-size model, and did not seem serious, as

Jan 1, 1915

In 1970, the federal Clean Air Act was passed, promulgating limits on the emissions of sulfur dioxide (SO2) from large stationary sources that would affect local air quality. The brunt of this regulation was felt by the electric utility industry, especially those units generating electricity with coal-fired boilers. The law hastened development of a new industry, flue gas desulfurization (FGD), which is composed of three major segments: the electric utility, the FGD equipment suppliers (the scrubbing modules), and the scrubbing chemical suppliers. Dravo's experience suggested the equipment end of the business, but market analysis recommended investigating the chemical processes involved in the removal of the SO2 gas. This resulted in the formation of Dravo Lime Co. to manufacture and market reagents to the FGD industry. This paper will briefly describe the Thiosorbic lime scrubbing process and review Dravo's innovative mine and calcining facility.

Jan 1, 1982

By F. V. Lenel

R. P. Seelig.*—Dr. Lenel is to be congratulated on his presentation of a particularly interesting paper describing the use of the powder metallurgy process for the production of magnetic pole pieces. The only thing that might be added is that we have been successful in producing pole . pieces with a narrow hysteresis curve by the use of considerably lower sintering temperatures than the ones used by Dr. Lenel. It is quite possible that this use of lowe- temperatures has considerably widened the field of commercial application for pole pieces made from metal powders. Development work is currently being done on an a.c. application of a sintered iron part. However, I am in full agreement with Dr. Lenel that if eddy currents are an important factor in the application, we cannot substitute sintered material for laminated sheet-metal structures. Mr. Peters' remarks concerning the limitations of machine parts were well taken. The emphasis of the limitations makes it easier to define clearly what we can do and-what the advantages are of machine parts made of metal powders. When I mention metal-powder machine parts, I mean those of relatively high density, although complete elimination of porosity is not possible at this time. The limitations of the field for this type of parts are largely economical. I believe that Mr. Langhammer has made that point very clear. The following questions are very often asked: How large a part can you make? How close can you hold the dimensions ? How fast can a part be produced? In a majority of the cases, it depends on the cost at which the part can be produced. A large variety of shapes and sizes of a number of materials can be formed. However, the main requirement in this field of endeavor is whether this can be done more economically by powder metallurgy than by other manufacturing methods. As a general indication, it may be stated that densities up to 95 per cent of that of rolled material can now be produced commercially in simpler parts. Tolerances of plus or minus 0.001 in. are common, but where special conditions justify, closer tolerances can be held; we are producing a part of which one dimension is held to 0.0003 inch. Finally, as far as maximum size is concerned, technically this would depend on the capacity of the press and furnace equipment available. Actually, we find that the economical limit of powder-metallurgy machine parts is approximately one pound. From there on, each individual case must he studied on its own merits.

Jan 1, 1945

By Franklin Moeller

Discussion of the paper of FRANKLIN MOELLER, presented at the New York meeting, February, 1916, and printed in Bulletin No. 110, February, 1916, pp. 343 to 354. K. A. PAULY, Schenectady, N. Y.-I read with interest Mr. Moeller's paper descriptive of the mechanical parts of the new electric hoist at the Granite Shaft of the North Butte Mining Co. and as the paper treats largely of the mechanical equipment I have little discussion to offer. There is, however, one question which I would like to ask and that is, why the discrepancy in hoisting cycles between the curves given in the paper read by Mr. Sykes for the American Institue of Electrical Engineers at San Francisco and those given in the paper under discussion? In Mr. Sykes' curves the acceleration period is shown to be 16 sec. for all depths from 2,000 to 4,000 ft. inclusive, while Mr. Moeller in Fig. 2 shows 25 sec. throughout the range and in Fig. 4 shows 35 sec. Mr. Moeller's curves also show the following reductions in the peak load during acceleration: Level, Feet Mr. Sykes, Horsepower Mr. Moeller, Horsepower 2,060 3,500 3,130 3,000 3,800 3,480 Fig. 2 4,000 4,100 3,800 2,250 1,595 Fig. 4 As the purchaser's specifications called for 15 or 16 sec. I would like to know whether or not any modifications have been made in the requirements since the equipment has been installed.

Jan 5, 1916

By H. S. Coe, G. H. Clevenger

Engineers have long recognized the desirability of correlating the data obtained from small-scale slime-scttling tests with commercial work as carried on in large tanks. This need, though most apparent in designing new installations, frequently arises also in existent plants, since a large range of experimental work can be performed without interfering with regular operation. General Settling Phenomena In order to develop rational methods of laboratory testing, it becomes necessary to study the general phenomena of settling. Since it was desired to give the public the benefit of these methods at as early a date as possible, together with the knowledge of the general principles of slime settling necessary for a clear understanding of the laboratory tests, we have ventured to discuss the subject in so far as brought out by the work which we now have under way. We realize that certain of our preliminary conclusions may be subject to modification, but it seems probable that, with but few exceptions, the general laws enunciated will cover the settling behavior of all pulps encountered in metallurgical plants. However, it must be recognized that there is still a vast amount of work to be done upon certain phases of the subject; therefore, at this time we will attempt only a discussion of the behavior of ore pulps during the process of settling or dewatering, under certain given conditions. The laws and principles controlling these conditions are not fully established, so that a complete discussion of them will not be attempted in this paper. In metallurgical practice, slime pulp consists of water, finely divided sand

Jan 1, 1917