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By John Wulff

In a previous paper Burwell and Wulff1 have shown by electron diffraction studies that allotropic transformations can be induced in 18-8 stainless steel by polishing to a depth of about 5 X 10-5 cm. The development of a successful etching technique, which removes accountable amounts of metal from the surface without pitting and without changing the root-mean-square profile as measured with an Abbot pro-filometer, led to the application of the whole technique and material to an investigation of various mechanical methods of surface preparation, such as grinding, lapping, superfinishing and cold-rolling. Ideally suited to such a study is 18-8 of low carbon and nitrogen content. The material can be heat-treated to produce a coarse-grained single-phase structure. On cold deformation there occurs not only a reduction in grain size but, at regions of maximum stress, a change of face-centered material to body-centered material, provided the metal is worked below about 200°C. When worked between 200"about and 415°C., diffraction studies evidence a reduction in grain size without the appearance of any new body-centered ferrite. Ferrite, which can be referred also to strains induced by carbide precipitation, is evident when the material is worked at temperatures between 4150 and 800°C. Stainless steel is advantageous because the usual surface-finishing operations do not readily oxidize it to any appreciable depth. In order to produce detectable oxide films on the surface of austenitic 18-8 in a time equivalent to that required to produce, for example, a fine ground finish on 1/2 sq. in., the sample must be held in a furnace or oxygen stream above 600°C. By using longer heating times, it is possible to achieve measurable oxide films on samples , whose surface temperatures exceed only about 250°C. Experimental Procedure The apparatus, material, and technique described in the previous paper1 were employed in this investigation. Samples of 18-8, I by I cm. by 4 mm., were carefully annealed in the austenitic range to produce a coarse-grained structure. They were then quenched and pickled to remove scale, On a lapping machine of the Graton2 type, both sides of each sample were polished to a a of 1/6 a wave length of sodium D light. Thereafter they were electrolytically etched to remove at least 1 X 10-3 cm. of the surface, a depth that is well below that of any defermations induced by surface preparation. samples of this material, carefully mounted in steel holders, were then sent to various industrial organizations known for special finishing techniques. In the instrue ment shops at the Massachusetts Institute of Technology check samples were finished by the same methods, as far as they were available. Abbot profilometer3 readings Were made on all the samples, which were then carefully degreased in double distilled benzine and alcohol, dried in a hot-filtered air blast, and kept in a desiccator. SUC-

Jan 1, 1941

By E. E. White

In August, 1911, I read a paper before the Lake Superior Mining Institute1 on surveying and sampling diamond-drill holes. The present paper gives a more thorough descriptiou of these methods, together with a few changes and notes suggested by further experience. Since August, 1911, the methods, used constantly by the Cleveland-Cliffs Iron Co., have been developed to a higher degree of efficiency, and have given great satisfaction. Until a few years ago but little attention was paid to the determination of the actual course of drill-holes, to the accurate sampling' and analysis of the material, or to the scientific location of the drill-holes. It has now been common practice for several years in many districts to test the inclination of drillholes by etching glass tubes with hydrofluoric acid, but the direction of deviation from the vertical has not often been determined. Methods of determining the direction by means of a compass were first developed in connection with drilling in Victoria. The latest method used on the Rand in South Africa has been recently described by John I. Hoffman.2 In the same paper Mr. Hoffman describes an ingenious method of wedging-off a drill-hole so as to start new holes at several successive points. By this means a hole can be deflected in any desired direction, and the curvature can be controlled to a considerable extent, provided the rock is soft enough to permit the hole to be wedged off. Unfortunately, in the Lake Superior district, the jasper iron-formation is so hard that it is very difficult, if not impossible, to do this. I tried to deflect one hole so as to avoid drill-rods stuck in the hole, by using a

Jan 1, 1913

By R. E. Grace, H. W. Schadler

DARKEN1 has established the theoretical relation between the self-diffusion coefficients and the Boltzmann-MatanO Or interdiffusion coefficient: D is the Boltzmann-Matano or interdiffusion coef-

Jan 1, 1960

By C. M. Young

This is an attempt to bring together some of the knowledge of the coal-forming conditions obtaining during the Pennsylvanian period in the Western Interior Coal Province, to sketch briefly the present extent and character of the coals produced, and to show the beginning of correlation of beds over wide areas. Coals of later age than the Pennsylvanian are not included and, for reasons that will appear later, little attempt is made to cover the districts of eastern Oklahoma and western Arkansas, and northern Texas is omitted entirely. Geological Conditions The conditions that made possible the formation of large coal beds in the United States were most favorable in the Pennsylvanian period, formerly known as the Upper Carboniferous. The geological conditions can be determined from the records, but not the reasons for them. Preceding the Pennsylvanian was the Mississippian, formerly known as the lower Carboniferous and still later as the sub-Carboniferous. During this time, large bodies of limestone were deposited and at the close of the Mississippian they were warped upward and for a long period were eroded. Then there began a period of subsidence, more or less interrupted at times, during which the Pennsylvanian strata were deposited (see table on next page). These consist of sandstones, limestones and shales, with occasional coal beds. At the beginning of the Pennsylvanian there was subsidence, which allowed the sea to extend over the eroded Mississippian surface to the north and east. It passed over eastern and central Texas, a large part of Oklahoma, with a projection into Arkansas, over Kansas and part of Nebraska, all the northern and western part of Missouri, a large part of Iowa except a strip in the north, most of Illinois, practically all of Kentucky, northern Tennessee, most of Indiana, all of the eastern part of Ohio, practically all of West Virginia, western Maryland, the west end of Virginia, and a large part of Pennsylvania. The Ozarks were already up and separated the main body of this sea, which covered the northern

Jan 1, 1936

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, 1935

By Howard Eavenson

The data given in the paper were collected to furnish an idea of the amount required in various operations of bituminous mining to produce a ton of coal, the plants selected being well-managed ones. With these are included some figures compiled from U. S. Coal Commission's report showing the average amount of labor in various classes of mines. THE information contained in the following paper was collected at the request of the U. S. Coal Commission, and is, published with the permission of that body and of the various companies furnishing the data. For obvious reasons, the names of the companies are not given. No data were gotten from States south of Virginia or west of the Mississippi River. The data about the amount of labor, in man-hours, required in producing a ton of bituminous coal have been collected with the idea of showing what is being done at some well-managed plants, and not to show the average amount required by all mines, which undoubtedly is considerably higher than the average of the figures shown.* Almost all of the figures were supplied by the various companies in reply to a questionnaire; when they were obtained from other sources the company was asked to verify them. On account of the amount of work required, the data were only requested for one or two months for each plant, and the figures represent in each case a month when the car supply was good and the work was practically steady. In the case of most of the West Virginia and Kentucky mines, these conditions were best met in May and June, 1922. The mines for which the figures are given are arranged by states and as to whether the mine operates under union or non-union or open-shop conditions. The union mines listed are generally considered to be as well-managed as are the non-union ones. The production per month in a few cases includes the amount of slate which is loaded and hauled out of the mine, as of course this requires nearly as much labor per ton as does the coal. These cases are noted:

Jan 1, 1924

By Samuel Daniels

Aluminum-base alloys containing small amounts of copper and magnesium possess but ordinary physical properties as sand cast, but may be treated to give a remarkable range of tensile values and of Brinell hardness. The high-copper (4.5 per cent.) duralumins must be given a protracted treatment which in nature resembles the malleableizing of white cast iron; the low-copper (2.25 per cent.) duralumins develop an excellent combination of strength and ductility with a treatment which requires a maximum of 5 hr. to be completed. THE wrought alloys of aluminum with small amounts of copper and of magnesium have, with the development of the automotive and aircraft industries, sprung into prominence through the medium of duralumin; but the cast alloys remained in the background because their possibilities in the heat-treated condition were either not recognized or not fully investigated. In 1919, the Bureau of Standards published a preliminary survey1 of this field, which pointed out that, in general, the ultimate strength and the percentage of elongation of the alloys of aluminum with and without magnesium could be improved by so simple a treatment as heating to 932° F. (500° C.) for 2 hr., cooling in, air, and aging at room temperature for several days. British investigators, too, working with chill-cast material, found that " considerable improvement in the mechanical properties of copper-aluminum alloys' may be obtained from suitable heat treatment applied to castings."2 Jeffries and Gibson3 made the first contribution to the literature dealing exclusively with the heat treatment of sand-cast aluminum-base alloys, describing the effect of small additions or of combinations of copper, magnesium, and iron on the response to a short heat treatment comprising heating at 932° F. in a

Jan 7, 1924

By Thomas H. Clagett

ThE Pocahontas coal field comprises the area in Tazewell County, Va. and Mcrcer and McDowell counties, W. Va., in which Nos. 3 and 4, Pocahontas seams of bituminous coal are mined. It is a mountainous region with ridges rising 300 to 1000 ft. (91 to 305 111.) above the very narrow valleys and, except for some poorly kept farms along the tops of the ridges and the area occupied by the mining and coking plants and villages, is wooded throughout. First shipments were made from Pocahontas in 1883. There are now about 100 mines, 95 per cent. of which are drift mines. At the end of 1920, approximately 298,000,000 gross tons of coal had been produced and 35,000 acres of coal mined. No. 3 seam is from 4 to 10 ft. (1.2 to 3 m.) thick, but the change is gradual and the thickness fairly uniform in any particular locality. It has a streak of bone, about 2 in. (5 cm.) thick, to which the coal adheres on both sides. In parts of the field this bone is replaced by hard slate, usually from 2 to 4 in. thick. The seam has a slate or fireclay bottom and a draw-slate top. No. 4 seam is from 65 to 80 ft. (19.8 to 24 m.) above No. 3 seam, and of minable section only in the western part of the field. It is from 3 to 8 ft. thick and has two streaks of bone, cach from 1 to 2 in. thick. It has a fireclay or slate bottom and is overlaid by from 4 to 24 in. of a laminated coal and slate, locally termed "black rash," which is separated from the coal seam by about 3 in. of slate. This "black rash" averages about 2.5 per cent. ash, but contains some clean coal. The coal in both seams is quite soft. Cleavage sufficieiltly well defined to exert an influence on the mining is rare. Overlying strata arc slates, shales, and sandstones, the sandstones predominating, extending from 30 to 1000 ft. above No. 3 seam. The strata directly above the draw slate of No. 3 seam, or "black rash" of No. 4 seam, and up to the first sandstone are usually slates or shales, about 10 ft. thick over the.

Jan 1, 1923

By James A. Barr

The writer's first experience with flotation was during World War I, in the bene-ficiation of Alabama graphite schist ores. One plant used a cone with a peripheral overflow; dried ore was distributed by a rotating disk onto the surface of the water. No reagents were added' The flake-graphite film floated along with some fine silica. Dewatering screens separated the flake. Naturally unit capacities were low but results were satisfactory. Minerals separation mechanical flotation machines were used in another graphite mill. pine oil was added directly to the head cells, with very good results. All the graphite concentrates from both types of flotation were carefully refined after drying by passing through burr mills, followed by very close sizing on sifters. In March 1927, the writer ran a very successful flotation test on minus 28-mesh, deslimed, Tennessee brown phosphate "sand,"† using a mechanical laboratory machine built in the shops of the Anaconda Copper Mining Co., through the courtesy of Ernest Klepetko. The machine was soon converted to a subaeration type, with improved results. This phosphate research program was greatly enlarged and led to the formation of the phosphate Recovery corporation. The development of nonmetallic flotation followed rapidly. The first flotation machine for bene- ficiation of phosphate was installed in January 1928, in a pilot mill, by International Minerals and Chemical Corporation, at Mulberry, Florida. These machines were Minerals Separation, 24-in., sub-,,,tion types, with weir control of pulp between cells. The sand bleeders were very small—about 1¼-in. diameter. As the feed flake. Is to 25 per cent plus 28-mesh material, the cells choked up frequently. This was corrected by cutting a 2 by 6-in. bleeder opening above the impellers, at grid level, which short-circuited the coarse fractions directly into the feed of the next cell. The matter of size classification and grinding was a considerable problem, which does not come within the scope of this article. Because of the troubles noted above, cascade-type roughers were installed in the second flotation plant, built about 1930. Experimental cells had been tried in 1928. General plant layout is shown in Fig. 1 and details of the cascade construction in Fig. 2. The cascade installation in plant NO. 2 gave good results and eliminated troubles due to choke-ups and coarse feed. The capacities and metallurgical results equaled those of the modified 24-in. Minerals Separation flotation machines in plant No. I The objections to the cascade installation are the floor space and mill height required. In 1939 an improved Minerals Separation machine was tested in parallel with the cascades. Extensive tests indicated

Jan 1, 1947

General discussion on the above subject, presented at the Pittsburgh meeting, October, 1914. GEORGE S. Rice, Pittsburgh,. Pa.-Undoubtedly there is a serious problem through the juxtaposition of gas and oil wells and coal mines, not only at the present time, but possibly of far more serious import for the future. If one examines a map of the coal fields on which is superposed the oil and gas fields of the country, one finds that they overlap to a very great extent. I may say at the beginning that we have not, so far as I know, had any very large number, of accidents growing out of this situation causing loss of life. Such accidents, or rather incidents, that have occurred have all been rather potential possibilities for disasters due to the leakage of gas from wells into the adjacent coal mines. The condition has been most acute in the Fairmont district of West Virginia, and in the general coal fields southwest of Pittsburgh in Pennsylvania. The accidents which have actually occurred were summarized in Bulletin No. 65 (Oil and Gas Wells through Workable Coal Beds) issued by the U. S. Bureau of Mines, reporting the transactions of several meetings in Pittsburgh, February, 1913, of oil and gas well representives, State geologists, State mine inspectors, coal-mine operators, and representatives of the U. S. Bureau of Mines. This conference was partly brought about through a case in which the Pennsylvania State inspection department had brought suit to restrain a gas company from completing a well through a certain mine. The office of the Attorney General of Pennsylvania asked the opinion of the Bureau of Mines upon the matter; about the same time the Association of State Geologists, at its New Haven meeting, asked the Bureau to take up the problem. Accordingly, it was thought advisable to bring together the several, interests. For the most part the danger is, I think, greater in the future, than at the present time Many parts of the coal fields of Pennsylvania, in Greene County particularly, have been penetrated by numerous wells very close together, and with the present practice of having a large coal pillar around each well, has made or will make the mining of many areas difficult or pro-

Jan 4, 1915

By T. Prof. Egleston

ALL industrial establishments whose operations depend upon chemical reactions use gases. In the simplest case the oxygen of the atmosphere, heated or not, as the case may be, is used, and in other cases, gases which are produced by a special apparatus of more or less complex composition. The manufacturer depends, for the success of his operations, entirely upon having these gases arrive at the right time, in the proper proportions, at the required temperature. It often requires but a slight variation in their composition to make a given process a success or a failure. In most cases the gas used is formed from fuel, and according as variations in its composition are produced by alterations in the manner of charging the grate, not only different, but often directly opposite, results are obtained. The great industrial question of the present time, and one upon which the prosperity of the world depends, is how to get the greatest amount of useful effect from fuel, whether the caloric is used directly or is transformed into horse-power. In almost all industrial pursuits this translates itself into the question of how to construct a fireplace and its adjuncts in such a way that the heat of the flame and of the products of combustion shall be made to produce a maximum effect. Unfortunately, until very recently, except by comparison, there was no means of ascertaining whether the loss of useful effect was 80, 40, or 20 per cent. of the total amount of fuel employed. It seems now strange that there should have been furnaces so constructed as to produce 20 per cent. of carbonic acid in the fireplace, but this has been proved by analysis to have been true. It does seem incredible that, notwithstanding the immense number and variety of furnaces used for different processes, and the great difference in kind, quality, and quantity of fuels consumed, there should formerly have been used for them all, the same stereotyped fireplace, varied only in its dimensions of height, length, and breadth. It is true that, with a good fireman, excellent effects may be, and have been, produced, but the manufacture is here, as in many other cases, dependent on the intelligence of the workman, a very uncertain reliance for capital to rest upon. The workman, unless he receives a prime for fuel saved, or is fined for excessive use of it, may be said

Jan 1, 1874

By M. Gangal, B. Paul

It may be seen from Maurer's survey (Maurer,l 1966) that most of the common methods used in rock drilling today depend upon mechanical loading of the rock. In order to predict the behavior of rock under an imposed system of stresses, it is necessary to have a valid criterion which delineates those combinations of stress which cause macroscopic rock failure from those which do not. Admittedly, the conditions under which brittle materials fracture depend very much upon statistically variable local effects such as inclusions, grain boundaries, minute imperfections, etc. However, it is extremely desirable to be able to predict fracture under complex states of stress by means of a stress-criterion of failure, where, for a given material, the effects of the other variables mentioned are incorporated into a small number of experimentally observable parameters. One of the most successful of these "macroscopic stress criteria" has been the Coulomb-Mohr theory 2,3 (also see Jaeger 4 and Terzaghi 5), modified by the addition of tension cutoffs (Paul 6). At first thought it might seem rather odd that a macroscopic theory is capable of predicting fractures which originate at highly localized random imperfections at an atomic level (or more likely at the level of individual mineral grains in rocks). However, Griffith7 showed that fractures originating near the tips of randomly oriented elliptical cracks lead to the macroscopic stress criterion of failure indicated in Fig. 1 (a). Fig. I (a) is to be interpreted in the following way: P and Q represent the maxi mum and minimum principal stresses (compression is considered positive) in a macroscopically isotropic body; fracture will not occur for any combination of principal stresses lying within the 'fracture curve' shown, but

Jan 1, 1967

By B. E. Parsons

Curtailment of production of crude oil, to the extent of effecting an approximate balance in supply and demand, was a problem confronting the oil industry in California throughout the year 1930. At the beginning of the year, with drilling operations only slightly checked, the California industry faced a steadily increasing potential production, an actual production in excess of market requirements and stocks of crude oil and refined products which had reached staggering proportions. During the year, the intensive development of the Playa Del Rey field and extensions to several oil fields, together with flush production from numerous large wells from both new and old fields, caused a steady increase in the state's potential production to a record peak in November of 1,186,000 bbl. daily. Despite the burden of this steady stream of flush production and the handicap of incomplete cooperation in several fields, curtailment successfully lowered the trend of crude oil production in California, except for the period of an open-flow test to determine actual potential production in several important fields in February. Under the curtailment programs in effect, the state's production of crude oil for the year was reduced 22 per cent. under the production of 1929 and even slightly under the production for the years 1927 and 1928. The total stocks of crude oil and refined products were reduced 2.7 per cent. during 1930, as compared to an increase of 30 per cent. in total stocks of all products during 1929. Drilling operations were reduced 28 per cent. as compared to drilling activities during 1929. Voluntary curtailment of drilling programs by many operators, particularly the major companies, accounts for the greatest portion of the reduction in drilling activity. The decline in drilling activity at Santa Fe Springs and in the east-side fields of the San Joaquin Valley was more than offset by development in new fields and extensions to deeper zones of old fields. There were 755 new wells completed during 1930, as compared to 910 completions in 1929. At the close of the year, 220 wells were drilling in the oil fields of California, 9 of which were being drilled in search of deeper producing horizons.

Jan 1, 1931

By Paul A. Farrar, Louis P. Stone, Harold Margolin

The Ti-Mo-0 system was investigated in the region 0 to 45 wt pet Mo and 0 to 10 wt pet 0, from 600° to 1400°C. Solidus data are also presented. Isothermal sections at 700°, 900°, 1100°, and 1300°C, and vertical sections at 1 and 28 wt pet Mo, and 1 and 10 wt pet 0 are included. STUDY of the Ti-Mo-0 system has been carried out as part of a general study of titanium phase diagrams. The binary Ti-Mo system has been investigated in whole or in part by several investigators.1-8 It was found that molybdenum and ß-tita-nium form a complete series of solid solutions and that the ß/a + ß transus is depressed to below 600°C at approximately 30 pet Mo.* The Ti-O system has been investigated partially or fully in the range 0 to 30 pet 0 by several investigators." Extensive solubility of oxygen occurs in the field. While a is

Jan 1, 1957

By A. J. Lynch, E. V. Manlapig, J. S. Hall, G. C. Thorne

Modelling of industrial sulphide flotation based on data collected in several flotation plants is discussed. A mechanistic approach is used in which it is recognised that flotation is a two stage pro- cess with concentration occurring both in the pulp and in the froth. The important features of the model, which is a kinetic model, are – 1. for each particle species there is a range of flotation rates which corresponds to the range of particle sizes, 2. the flotation rates of the liberated gangue particles which have no hydrophobic properties are dependent on the flotation rate of water and are controlled by variables such as the air and frother addition rates, and the pulp level, 3. as an approximation the valuable sulphide particles may be regarded as being present in two groups with high and low flotation rate constants, 4. increase in the addition rate of collector tends to increase the proportion of sulphide particles which are in the high flotation rate constant group. The actual flotation rate of each group of particles is a combination of an "inherent" flotation rate and a flotation rate which is dependent on the flotation rate of water, 5. at particular air and frother addition rates and pulp levels there is a physical limit to the rate at which particles can be transported into the concentrate and this is recognised in the model. The model has been used to study the steady state and dynamic properties of flotation circuits in operating plants. The assessment of the behaviour of composite particles is difficult because of the problem of quantitatively describing the surfaces of mineral particles. A method which is being developed to measure unpolished particles is described briefly.

Jan 1, 1976

By R. B. Gilmore, Lewis W. MacNauhgton

The North Texas district, as' herein defined, includes the counties of Archer, Baylor, Clay, Cooke, Foard, Hardeman, Knox, Montague, Wichita, and Wilbarger. This area covers generally the crest and south flank of a system of buried mountains known as the Red River uplift. The oil and gas accumulations along this feature are in traps, which, although localized by structures incident to the regional uplift, usually are modified by stratigraphic changes in the sediments. Excepting those in southeastern Baylor, southern Archer, and southwestern Clay counties, all the fields within the district are on this Red River uplift. These exceptions, which have the same type of oil and gas accumulation as the other fields, are on the extreme north end of the Bend arch, which is a broad anticline plunging northward from the Llano uplift in central Texas to Archer County. The larger part of past oil and gas production has come from Pennsyl-vanian strata, with less important amounts from the Permian, and minor but increasingly important quantities from the Ordovician. Developments during 1942 Approximately 500 wells were drilled in the district during 1942, in contrast with some 1600 wells drilled during 1941, and only some goo oil wells were completed, a decrease from 1941 of more than 10 per cent in the number of successful drilling operations of the total wells drilled. Production increased slightly over the previous year in spite of a decrease in the number of producing wells. The average depth of discovery wells was some 600 ft. deeper than in 1941. Although more discoveries produced from horizons above the base of the Strawn series than those below the Strawn, the deeper horizons, including the Bend series of the Pennsylvanian, the Mississippian limestone, and the Simpson and Ellenburger of the Ordovician, furnished most of the addition to oil reserves. The largest single addition to the reserves was again in the Ellenburger formation in the K. M. A. field. During the year 47 wells were completed, bringing the total developed acreage in this horizon to some 5450 acres. The most active area was Montague County, in which eight fields, or potential fields, were discovered although only 39 oil wells were completed. K. M. A: Pressure Maintenance Satisfactory progress was made by the K. M. A. Pressure Maintenance Association in 1942, At the end of the year, 100 wells were being used for input and total monthly volume of gas returned to the reservoir reached a high of 430,971 M cu. ft. in December, with an input ratio of 587 cu. ft. of gas returned for each barrel of oil produced during the month. This represents a utilization of 50 per cent of the gas available for return during that month. Comparison of the present average bottom-hole pressure by means of a decline

Jan 1, 1943

By J. W. R. Rayner

THE conventional method of making water gas involves individual plants for the separate carbonization of coal to coke and the subsequent gasification of coke with steam. The process demands lump coke, preferably made from the best quality of coking coals. The ash in the coke should have a high melting point and the gasification process suffers a loss of efficiency when cokes with law ash-melting points are used. In Britain, these coals are generally the most expensive and they are readily available only in certain localities. The coals not suitable for making lump coke, or yielding only poor quality coke, are much more widely available and are generally cheaper. DEVELOPMENT OF ALTERNATIVE PROCESSES In Germany, processes have been developed and operated commercially for the production of water gas from very low-rank coals such as brown coal and lignites, but much less effort has been spent on processes to use coals of intermediate rank, which are widely available in Britain. The brown-coal processes use coal in the form of either dust or briquettes. The most successful of the dust-gasification methods is the Winkler process, which made a substantial contribution to German oil production during the war. It uses coal in the site range 0 to 8 mm and the fuel bed is blown with a mixture of oxygen and steam at a rate high enough to give it a characteristic boiling motion or, in present-day phraseology, at a rate more than sufficient to fluidize it (Fig. 1). Air cannot be used to provide the heat required for gasification, for various reasons. In the first place, to make the process continuous by mixing air and steam would involve the production of a lean gas-containing much nitrogen. If a separate blow were used, a large amount of potential heat would be lost because the blow gas in such a process would contain a very high percentage of carbon monoxide. Oxygen is necessary therefore and oxygen remains relatively expensive for use in gasification. In the Winkler generator, formation of clinker caused by local overheating does not occur, because of the mobility and high heat transfer of a fluidized bed. These properties of fluidized dusts have been used most successfully

Jan 1, 1953

By H. S. Munroe

AN elaborate discussion under this heading formed a chapter in one of the reports made by Professor Raymond as Commissioner of Mining Statistics.* In a subsequent report- was printed a paper, by Mr. William Main, Jr., of Columbia, South Carolina, containing a theoretical investigation into the effect of the velocity of impact on the effective ditty of stamps. A visit to the Lake Superior copper region last summer suggested an inquiry into the relative efficiency and economy of the enormous steam stamps of the copper-mills, as compared with the results obtained with the cant and tappet stamps commonly used in the West. The atmospheric stamp used at the Phoenix Mill promised to add interest to the inquiry, as giving an example of unusually high speed, this stamp making 160 drops per minute. In introducing his subject Dr. Raymond makes the following remarks, which are quite apropos of the present investigation : "In considering the economical application of stamping machinery, we meet, at- the beginning, with serious difficulties in obtaining accurate data for comparison. The weight and fall of stamps vary as the shoes and dies wear out; and this may lead to a change of speed also. Moreover, defects in engines, boilers, or machinery for the transmission of power, may occasion serious losses, which cannot fairly be charged to the arrangements of the stamps proper. Again, the capacity of stamp-mills is directly dependent, in some degree, upon the nature and extent of discharge, fineness of screens, and other peculiarities of the battery. Finally the hardness and tenacity of the rock crushed varies so much that comparisons between different localities cannot be implicitly trusted. The safest experiments are those made in the same mill, by changing first one and then another condition of working; but this is seldom possible for such * Mineral Resources West of the Rocky Mountains, 1871, p. 380. †- Mineral Resources West of the Rocky Mountains,, 1873, p. 345.

Jan 1, 1881

By James Douglas

American metallurgical inventions have not always been absolute metallurgical improvements, if accurate work be the standard of comparison; but when we review the new methods and machinery which have been generally accepted, we find that some have become essential to the metallurgist the world over, while all are so admirably adapted to the peculiar requirements of our local conditions that they have entirely supplanted foreign processes and appliances. The necessity of diminishing to the utmost the employment of labor (owing to its great cost), and the inexorable requirements of our modern joint-stock corporate system, which demands that large quantities be worked up in order to secure large returns, regardless betimes of waste, have been the impelling motives to invention, and indicate the special directions in which originality has been exercised. As might be anticipated, the West has been the most fertile field of inventions by miners and metallurgists, by reason of its great and varied mineral wealth, locked up in ores sometimes lean and often of intricate composition, which must be profitably handled, at a great distance from fuel and from building-materials, by workmen who are paid wages very much higher than those received by their fellow-workmen of like craft in Europe, and in some localities twice as high as those paid for like services even in the eastern States. Moreover, paradoxical as it may seem, the technical inexperience of many of those engaged in mining and metallurgy has helped rather than hindered the progress of invention; fop while there may have been ignorance, there has been radical freedom from

Jan 1, 1894

By Frederic K. Bunton

The smelting plant of the British Columbia Copper Co. at Greenwood, B. C., now closed because of the decline in the price of copper due.to the European war, is of special interest to metallurgists for several reasons. It was successfully smelting in blast furnaces the lowest grade copper ore of all plants in America. In order to do so, it had to run at very hig~; efficiency, which necessarily required a large tonnage per square foot of hearth area, together with the minimum amount of labor and other costs. The furnaces smelted daily 2,250 tons of ore (6.62 tons per sq. ft. of hearth area), carrying 0.85 per cent. of copper, at a smelting cost of 81.18 per ton. The entire plant required 130 men to operate it and keep up repairs, showing a labor efficiency of about 17.5 Dons per man per day. In the present paper, the method of obtaining these results is shown. Most of the information contained in this description I obtained as Assistant Superintendent, during the two years preceding the present shutdown. Other sources of information to which I am indebted are: The British Columbia Copper Co., Ltd., by ALfred W. G. Wilson, in The Copper Smelting Industry of Canada; Greenwood Smelting Worlrs, by J. E. McAllister, Engineering and Mining Journal, vol. xci, pp. 1011 to 1015 (May 20, 1911); and Description of the Copper Smelter of The British Columbia Copper Co., by W. L. Bell, in Transactions of the Canadian Mining Institute, vol. xvi, pp. 151 to 154 (1913). II. Location and Connections The smelter of this company is about half a mile south of GreenGood, in the Boundary district of British Columbia, on the Columbia & Westerg branch of the Canadian Pacific Railway. It was originally built in 1900 by Paul Johnson, to handle 600 tons of ore a day in two small furnaces of 300 tons capacity; but in 1907 the old furnaces were torn out, the plant was remodeled, and three blast furnaces, 48 by 240 in. at) the tuyéres, were installed. In 1910, two of these were enlarged to 51 by

Jan 1, 1916