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By Herman Poole

When finely divided ferrous sulphide, FeS, is roasted at a moderate, carefully-regulated temperature, the iron and sulphur are oxidized, the first products being probably ferrous oxide and sulphurous acid. In the presence of oxygen of the air the ferrous oxide soon becomes ferric oxide, and, in the presence of oxygen and the ferric oxide, the sulphurous acid oxidizes to sulphuric acid. These facts are well known, having been established by Plattner many years ago. As a further reaction, some of the sulphuric acid parts with a portion of its oxygen to oxidize more ferrous oxide to ferric oxide, and a portion of it escapes uncombined, or else unites with the iron oxides to form sulphates. Ferrous sulphate is usually soon oxidized to ferric sulphate, and if the heat becomes sufficient, this is then decomposed into sulphuric acid and ferric oxide. As a result of these reactions a mass of more or less pure ferric oxide is formed which is generally made porous by the escaping gases and, if rabbled properly, practically all the sulphur is expelled. If ferric sulphide or ordinary pyrites, FeS2, is roasted, a portion of the sulphur sublimes and usually burns to form sulphurous or sulphuric acid, although at times and under favorable conditions, some of the sulphur is driven off uncombined, and can be collected as such. Under ordinary methods of roasting, however, only a small portion escapes combustion. By the combustion of the sulphur an increase of heat is developed and, as a consequence, the reactions mentioned take place more rapidly and actively,—more sulphuric acid is formed and the oxidation is more complete—nearly all the iron being left as ferric oxide with practically no sulphate or ferrous oxide. When the iron sulphide is in lumps the roasting proceeds generally as with fines, but with some changes due to mass. The

Jan 1, 1906

By H. T. Matson

IN the Northern Rhodesia copper fields the size of the orebodies and the exceptionally consistent values over great distances made it possible to outline the ore with drill holes spaced at 1000-ft. intervals; in some cases, 2000-ft. intervals.. Owing to the fact that the size of the deposits made it very evident that much outside capital would have to be called in to develop them and, owing to the wide spacing of the holes, it was essential that the sampling of drill holes be as accurate as possible, so that outside examining engineers could adopt the results as trustworthy within the limits of accuracy of the drilling method. With this object in view, the field staffs of the Selection Trust group of companies have studied for the past three years, and are still studying, drill sampling in a very thorough manner, and for this reason it is felt that these notes may be of interest to engineers or students who are, or in the future may be, in charge of drilling operations. The orebodies in this field lie in shales and sandstones, more or less indurated, in the lower strata of the Roan series, and the copper mineralization is in the form of sulfides predominantly, with some oxidized copper minerals. Those interested in the geology and history of the area can find full details in a recent paper by Anton Gray and Russell J. Parker.1

Jan 1, 1930

By E. G. Woodruff

THE earlier struggles in petroleum geology were directed to solving the origin and method of accumulation of petroleum. We are now fairly well agreed on those subjects. Most of us think that the great mass of petroleum commercially produced comes from plants or animals, or possibly from both. We are confident that the oil was not produced where it is now found but has accumulated in reservoirs of various kinds. The types of reservoirs are certainly variable but they just as certainly follow definite geologic laws. Some of these types of reservoirs can be determined from surface study; others cannot. We know, too, that these types of reservoirs (largely structures such as anticlines, domes, and terraces) are much more widespread than the oil pools. In other words, there are many places where good sands and good structures exist but where oil is not found. It is the purpose of this paper, therefore; to attempt to analyze, from a regional standpoint, some of the conditions that control the presence or absence of oil pools and to group them in a regional way, hence the term "Petroliferous Provinces." The paper lays no claim to presenting new facts but attempts to group and classify the information that so many have expressed again and again. The essential factors for an oil field are petroleum, a reservoir material, and conditions under which the petroleum can enter the reservoir but cannot escape except through the drill holes. The paper will first discuss the source of petroleum as it occurs in definite regions, then the regional arrangement of reservoir strata, and finally the areal arrangement of structures. To have petroleum, there must be a source. Since living matter is considered the source of the petroleum, geological conditions must, have been such that living organisms were abundant. Arid regions on the earth's surface have not given rise to living things-in sufficient abundance to produce oil; similarly, too cold regions and saline inland lakes. The converse of this is that warm moist conditions must prevail to produce an abundance of vegetable matter. Before an area can be

Jan 6, 1919

By E. W. Owen, John G. H. Crump, Peter P. Gregory

A noticeable decrease in activity characterized the year 1938 in the West Texas area. The total number of wells completed dropped to 2045 for 19381 as compared with 2806 completions in 1937,l a decline of 27.12 per cent. This trend contrasts the sharp increase of 76.29 per cent in completions in 1937 over the 1936 total. Of 2045 well completions during 1938,' 1788 were oil wellsll 16 were gas producers1 and 241 were listed as failures.' During 1938 the ratio of dry holes drilled to oil-producing or gas-producing wells completed was one dry hole to each 7.48 oil wells, which compares with one dry hole drilled to each 7.477 oil wells in 1937. Nearly 200 wells drilled during 1938 in West Texas were either wildcat or partly wildcat wells, an increase of about 25 over the year 1937, when approximately 175 wells drilled were so classified. The 200 exploratory wells drilled represent about 10 per cent of the total number of wells completed. West Texas produced 71,257,541 bbl.1 of oil in 1938 as compared with 75,743,000 bb1.2 of oil in 1937, a decrease of 4,485,459 bbl., or a 5.92 per cent decline. By comparison, West Texas produced 22.36 per cent more oil in 1937 than during 1936. In December 1938, the 9247 producing oil wells in West Texas1 averaged 22.08 bbl. per day per well as compared with December 1937, when 7571 wells1 produced an average of 25.18 bbl. per day per well, or a decline in daily well average of 12.32 per cent. Discoveries No outstanding new fields were discovered in West Texas during 1938, in spite of continued, active wildcatting operations. Several new oil-producing areas were, found, however, the value of which is still unknown.

Jan 1, 1939

The Delegation of American Engineers constituted by the American Institute of Mining and Metallurgical Engineers, the American Society of Civil Engineers, the American Society of Mechanical Engineers, and the American Institute of Electrical Engineers, that visited France in December, 1918, in acceptance of the invitation extended by the Congrés General du Genie Civil consisted of the following: Representing the American Society of Civil Engineers, Major James F. Case, past president, Geo. F. Swain, vice-president, Nelson P. Lewis, treasurer, Geo. W. Tillson, past director, Geo. W. Fuller, director, A. M. Hunt. Representing the American Society of Mechanical Engineers, president, Chas. T. Main. Representing the American Institute of Electrical Engineers, past president, L. B. Stillwell. Representing the American Institute of Mining and Metallurgical Engineers past-president, E. C. Spilsbury. The delegation organized on the way over by the choice of Major James F. Case as chairman, and Geo F. Swain as secretary. On arriving at Bordeaux, the Delegation was met by Mr. S. D. Brown, associate member of the American Society of Civil Engineers; and on its arrival in Paris it was joined permanently by the following attaches: Captain P. Charton, of the French Engineers, Delegate of the Commissariat-General to accompany the Delegation and serve as liaison officer; Captain Carpenter of the American Army; and Mr. Geo. Herdt, representing the Society of Civil Engineers of France. The object of the visit was to discuss with the French engineers the large engineering, problems now facing France. Engineering problems in their restricted technical sense came up for discussion practically not at all, for the French do not need advice nor assistance along strictly scientific lines. It was in the -larger and economic aspects of engineering, to aid in building up the industries and commerce of France, that our French associates desired to learn from the experience of the American Delegation.

Jan 9, 1919

By Stephen Birch

The Chitina mining district of Alaska is located at the headwaters of the Chitina and Copper Rivers. At present, the only producing mining properties are the mines of the Kennecott Copper Corpn. and the Mother Lode Coalition Co., which are situated 196 miles from Cordova, the port of entry. The first claims, later acquired by the Kennecott Mines Co. and afterwards transferred to the Kennecott Copper Corpn., were discovered in 1900. The Copper River & Northwestern Ry., which connects the mines with tide water at Cordova, was completed in the spring of 1911. Contemporary with the construction of the railroad, aerial tram equipment was brought to the mines by pack train and a tramway, 3 miles long, connecting Bonanza mine with the proposed railroad terminal, was finished, enabling shipments of high-grade ore to be made immediately the railroad was completed. A mill to treat the lower grade ore was begun the same year. The Kennecott company's holdings consist of 111 mineral claims. The Mother Lode Coalition Mines Co., which is controlled by the Kennecott Copper Corpn., owns 73 claims adjoining the Kennecott holdings. All data on operations and geology refer equally well to the Mother Lode property. Geology The general geology of the district has been covered by the U. S. Geological Survey1 and the geological features of the mines have been carefully studied by A. M. Bateman, in his capacity as consulting geologist to the company.2

Jan 1, 1925

By Gregory Comstock

THERE is a growing interest in the possibilities presented by the manipulation of metal powders, which justifies an attempt to summarize their character and potential value. A summary of this kind presents an opportunity for making a classification of metal powder products into several general types. Our present knowledge of the finer and more abstract aspects of many of the principles involved in metal powder technique is extremely limited. Any conclusions as to the ultimate value of the process will, therefore, for the present at least, be of doubtful value unless they are substantiated by its products. The number of such products is increas-ing. A study of their diverse and unusual characteristics; an examination of the methods by which they ale made, and a consideration of the reactions that take place during their fabrication, in so far as we can define them, should afford as good an evaluation of this interesting development as it is possible to make at this time. A critical study of this kind results in a formidable list of special attributes, which apparently are characteristic of applied powder metal-lurgy. A comparison of these special effects with the end products and well defined limitations of the melting and casting process indicate that often they may very well be considered as being special advantages. They are subject, of course, to certain not as yet so well defined limita-tions of their own. Based on current products only, a necessarily con-densed summary of the more striking special attributes of the metal powder process follows.

Jan 1, 1938

By Frank Hultgren

The influence of grain boundaries and polygonized subsructure on the flow stress of commercially pure aluminum has hem studied. A systematic inz-estigoti017 of grain size and subgrain size and mis-orientation was pursued; the contributions of pain boundary md substruture hardening were found to he additive fuiictions. Subgrain boundaries exert greater influence on hardening at room temperature than do grain boundnries. Both subgrain diameter and misorientation influence flow stress, but only to the extent that both contribute to the dislocation density. The flow stress due to substructure may he described by the equation of = abp1/2. THE origin of substructure hardening in metals has remained unclear for a long time. Lately, both theory and experimental techniques have become more exact and merit a closer examination of the subject. In the present work, the influence of polygonized substructure size and misorientation in commercially pure aluminum on mechanical properties has been systematically investigated. The influence of substructure on mechanical properties has been compared with that of grain boundaries. In addition, the works of several authors are compared with theoretical predictions of substructure hardening. EXPERIMENTAL TECHNIQUES Aluminum of 99.9 pet purity (0.04 Fe, 0.046 Si, 0.00 Cu) was employed. Various grain sizes were produced by heavy (over 90 pet reduction in area) cold drawing and recrystallization at various temperatures. A (111) fiber texture was observed in all specimens. Grain sizes were analyzed statistically. Substructure of varying size and misorientation was produced by prestraining specimens of various recrystallized grain sizes. Specimens for mechanical testing and substructure analysis were recrystallized, prestrained, and annealed together. The samples were prestrained from 5 to 25 pet in tension at room temperature and annealed at 200" to 370°C for 2 hr. All samples were rapidly cooled (in air) from the anneal to retain the subgrain wall structure developed at the annealing temperature. A clearly polygonized substructure was developed in all cases. Substructure size was measured by the Berg-~arrett' technique and analyzed statistically. Substructure misorientation was measured in the following manner. Individual grains in the polycrys-talline aggregate were isolated and their intensity distributions mapped using an X-ray goniometer and Geiger counter. From the observed profiles, the

Jan 1, 1964

By John B. Mertie

MONAZITE formerly was described as moribund, but, in the light of recent developments, it is no longer so. It is the common source of the rare earths and thorium, both of which are becoming progressively important in industrial and other applications. Moreover, by the action of foreign governments, the sources on which the United States has depended for its supply are now either restricted or cut off entirely. Monazite has thus become a scarce mineral and processors in this country are endeavoring to acquire it from all available sources. RARE EARTHS AND THORIUM The rare earths proper, as defined by spectroscopists, are the oxides of cerium, praseodymium, neodymium, prometheum, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutecium, with atomic numbers ranging respectively from 58 to 71. Chemists include with the rare earths scandium, yttrium, and lanthanum, with atomic numbers respectively of 21, 39, and 57. Thorium, with an atomic number of 90, is analogous to lanthanum, in that it precedes a second group of elements, whose oxides constitute the "rare earths of higher order." These are protactinium, uranium, neptunium, plutonium, americium and curium, with atomic numbers ranging respectively from 91 to 96. The last four mentioned are artificially prepared elements that so far have not been detected in nature. The rare earths with odd atomic numbers, except europium and lutecium, have no natural isotopes; and the two exceptions have only two isotopic forms. Those with even atomic numbers have from 4 to 7 natural isotopes. Samarium148 is radioactive, disintegrating over a half- life of 1.4 X 10 11 years with the emission of alpha rays. Lutecium176 is weakly radioactive, disintegrating over a half-life of 2.4 X 1010 years, with the emission of beta and gamma rays. At least 64 radioactive isotopes of the rare earths proper have been artificially prepared. Thorium is a strongly radioactive element, with a half-life of 1.39 x 1O10 years, which disintegrates through a series of 14 isotopes of 10 elements. The two longest lived and most important of these are

Jan 1, 1949

By W. W. Scott

The application of engineering methods to the problems connected with drilling and producing in the oil industry has led to the development of the science that is variously termed "petroleum engineering," "production engineering," "petroleum production engineering," and even Itpolitical engineering." It would require much detail to enumerate the qualifications of a petroleum engineer, just as it would for an engineer in any major industry. For those who have a genuine liking for the oil industry, there is a wide selection of pathways to achievement. The oil industry is now highly specialized. Its products are necessary to all civilized people and are indispensable in the security of our nation and also in the well-being of our families. The business structure of our country depends in a large measure upon oil, and the welfare of this group as individuals is certainly linked with the welfare of the oil industry. What Is the Trend of Engineering? The oil industry offers a fertile field of opportunity for engineering; probably more so than any other industry. The sciences of geology, physics, chemistry and mathematics are all used in some phase of the oil industry and to a very considerable extent in the production division, which embraces the geological, drilling and producing departments. In drilling and production alone, research programs of considerable magnitude are being carried on at this time, and no doubt the future will see a great deal more of this kind of work. Through the cooperation of the engineer, the equipment manufacturer, and the American Petroleum Institute, immense savings have been made by the standardization of drilling and production equipment. Drilling equipment in itself offers a wide scope for study, in that continued efforts are being made to improve the equipment so that it can be made to drill faster and to greater depths. The improvements in drilling equipment are required because new reserves of oil are being found at progressively greater depths. In order to produce such oil in competition with oil now being produced from reservoirs

Jan 1, 1937

By Robert C. Beckstorm

Russia produced over one-half of the world's petroleum in 1901. It dropped to a low figure in 1920 during the reorganization of the new government. Since then it has had a remarkable growth under the constant demands from the Central Bureau at Moscow. The five-year plan called for the development of all industries, many of which had permitted their equipment to gat out of repair or become obsolete, so that when the magic wand of authority demanded that they double, triple or quadruple their former production they looked to the oil industry for aid. This plan made necessary the building of new factories, dams and power stations; the developing of mines and agriculture, and in many places the building of cities and railroads. Exports were the solution and petroleum was the logical one to carry the load of development of the more backward industries. It had a ready market and fields located advantageously for transportation, which was cheap, and there was sufficient oil to meet the market demands at that time, as domestic consumption was not great. The building program demanded new and modern machinery and technical aid from abroad. FIG . 1.-PETROLEUM Money was necessary and petroleum was the impor- 1925-1931. PRODUTION IN RUSSIA tant product of exchange. This accounts for the rapid development of the old fields, the search for new ones and the building of refineries and transportation facilities. Fig. 1 shows the advance in production since 1925. There has been a. steady increase since 1920, and with the improved drilling equipment and improved methods it will increase as long as the now proved fields continue to produce new wells. The fields of Baku and Grozny have yielded 95 per cent of this production. The Cara Chukur field, which is being developed at the present time, is an extension of the Surakany at Baku and may be considered a part of the old field. New fields are being

Jan 1, 1932

By Theron Wasson

Michigan produced 16,637,000 bbl. in 1937. This makes it a record year in the history of Michigan's oil industry. During the year 953 wells were completed; 779 within the limits of established fields and 174 wildcats; 616 new oil wells, 68 gas wells and 269 dry holes. Table 1 has been arranged in alphabetical order of field names. Production figures for 1936 have been corrected because December figures were estimated. In this year's summary, December production is based on actual reports. The Leaton and Mt. Pleasant fields have been re-defined. Mt. Pleasant production north of the south line of Denver township, Isabella County, has been included with Leaton in accordance with usual practice in Michigan. The locations of fields discovered since the last map was published1 are shown in Fig. 1. Activity during 1937 Buckeye Field.—The Buckeye field of Gladwin County was the center of greatest activity during the year and was responsible for the increase of 4,700,000 bbl. over the state total for 1936. Buckeye produced 6,428,-000 bbl. in 1937. In this field 328 producing wells were completed during the year—over one-half the oil producers drilled in the state. Buckeye was subject to voluntary and cooperative proration from April 1 to the end of the year. Other pools of the state were not prorated. The new production at Buckeye is from porous Dundee limestone of Devonian age, similar to the older fields. Other New Fields.—The Sherman field was second in importance as a source of new production, with a total of 1,532,000 bbl. Salem township, Allegan County, on the southwest side of the Michigan Basin, was developed during the year. Production at Salem is from the Traverse limestone at a depth of 1600 ft., and 52 producing wells have been drilled in this pool. Other active pools were Clayton and Adams townships, Arenac County. The Bentley pool, discovered in October 1937 southeast of

Jan 1, 1938

By W. M. Clark

OUR interest in the matter of pyrometers and pyrometry is primarily that of a user of considerable quantities of heat-measuring equipment; and while we play be somewhat critical on the subject we have aimed to make the nature of these comments constructive. The glass industry in America dates back to 1609, when Capt. John Smith started a small glass plant near Jamestown, Va., with a few Italian workmen, to manufacture glass beads for trading with the Indians. While the industry has expanded until it has reached a volume of over $200,000,000 per annum, the means of heat determination in Colonial days was the human eye, and in much of the industry the same means is used today. About 15 yr. ago the largest glass-house supply dealers began to sell platinum pyrometers, but as nearly all of these proved un-satisfactory, pyrometers met a temporary rebuff from the old-time glass manufacturers. As their ruggedness of construction, reliability, and stability have been improved, however, pyrometers have gradually won their way into more and more extensive use throughout the glass trade. But there are still many applications where pyrometers are not used, largely because of cost and upkeep considerations. There are two distinct fields in glass works for pyrometry. The first calls for accurate temperature measurement and the second only demands knowledge of relative comparative fluctuations of temperature, to know whether the work is becoming hotter or colder. For example, in a lehr for annealing glassware and removing strain we want accurate temperatures to know that the ware is heated to the critical temperature for rapid removal of strain. On the other hand, in a glass pot furnace nearly 120 ft. (36 m.) in circumference, where the pyrometer couples only project inside the furnace wall for less than 2 in. (50 mm.), it is inconceivable that these few inches represent the accurate temperature at every point of the 120-ft. circumference but the relative readings as to whether the pyrometer shows schedule temperature fluctuations are valuable indications for control. The glass melting in the pots is,

Jan 8, 1919

By P. E. Demmler

The apparatus in which the process of bright annealing of copper wire was carried out consisted of a section of iron pipe, 6 ft. long and 3 ft. in diameter. The pipe was provided with flanges to which were bolted the end plates for sealing, also with inlet and outlet tubes to allow for the displacement of the air in the pipe by natural gas. After charging with copper wire, sealing and displacing the air, the pipe was heated to 350' C. (662" F.). It was expected that the natural gas would furnish a neutral atmosphere which would prevent oxidation and give a satisfactory bright-annealed product. It was found, however, that the outer layers of wire were discolored and not suited for the use for which they were mtended. To obtain an idea of what was taking place in the annealing furnace, skeins of the hard-drawn wire were placed in a glass tube so that all changes in appearance could be observed as they were heated to different temperatures and under varying conditions. The temperature in each case was determined by means of a thermocouple placed in the tube close to the wire. Following is a summary of the results of these experiments: 1. When the wire was heated for 1 hr. in a current of natural gas at a temperature of 350") 400") or 500" C. (662", 752", or 932" F., respectively), there was a marked darkening of the wire throughout the skein. 2. When heated for 1 hr. in natural gas at a temperature of 600" C. (1112' F.), there was no coloration, the wire remaining clean and bright. 3. When heated in natural gas to 350" C. until darkened and the treatment continued with the temperature raised to 600' C., the coloration disappeared and the wire became clean and bright.

Jan 1, 1923

By C. S. Trewin

ZINC, in its wrought form, is produced commercially in rolled strip, sheet, wire, rod and tubing. Wire has been made periodically, but due to the fact that slight drafts are necessary, the cost of production is greater than for the more common non-ferrous metals which are made into wire. Notwithstanding the cost, zinc wire has certain special uses for which it is particularly adaptable. Rod has been made both by rolling and extrusion, the product, however, has not indicated great commercial value. Tubing has been made from strip from time to time by forming a strip around a mandrel and either electrically or gas-welding a longitudinal joint. Recently a tube manufacturer has succeeded in making a fair quantity of this material. Its commercial adaptability is still to be determined but anyone who desires it can obtain quantities of the smaller sizes. Inasmuch as strip and sheet are commercially the most important, this paper will be devoted to these products. In the broader sense, zinc is not alloyed. That is, there are no combinations comparable to the various copper, aluminum and nickel alloys. It has been recognized,, for some time, that the lead and cadmium occurring with commercial zinc have some effect on its properties and such alloys as may be said to exist are those made from zincs containing varying amounts of lead and cadmium with a relatively low iron content. The foreign rolled zinc will analyze higher in lead than the domestic grades. A representative foreign analysis will run 1.1 per cent. lead, 0.07 per cent. cadmium and 0.02 per cent. iron. The American grades vary from zinc approximating high grade. and analyzing 0.08 per cent. lead, 0.002 per cent. cadmium and 0.015 per cent. iron, to the lower grades in which the lead will vary from 0.3 to 1.0 per cent., cadmium from 0.10 to 0.5 per cent. and the iron in the neighborhood of 0.02 percent.

Jan 1, 1927

By R. B. Adair, J. S. Browning

The Bureau of Mines conducted laboratory research to determine the applicability of heavy liquid separation to the evaluation of certain mica ores and plant products. After careful standardization of the particular mica ores and associated gangue, accurate analysis of muscovite content could be obtained from results of heavy liquid separation. Where applicable, the method should be particularly suited to the analysis of ores and control of plant operations wherein savings in time would be of considerable advantage. Specifically, there are many instances where a quick plant control method should enable the production of a more uniform grade of mica concentrate. The laboratory use of various heavy liquids for separating minerals of different specific gravities has been recognized for many years.1-8 Sink-float procedures have proven their utility as a rapid and moderately accurate means for determining the mineral content of ores, test products, and plant products in certain nonmetallic concentrating operations. A standard method of analysis for mica in ore samples has not been published or generally accepted by the mica industry. Recently, the U.S. Bureau of Mines investigated methods for analyzing mica by heavy liquid separation. This report has been prepared to make the methods available to others who may need simple, relatively rapid methods of determining the mica content of ores and plant products. The heavy liquid method of mica determination has recently been adopted by one of the major mica producers for evaluating exploration and mill control samples. DESCRIPTION OF THE ORES AND HEAVY LlQLllD The weathered mica pegmatite ores used in the investigation were obtained from commercial mica op erations in Alabama, Georgia, and North Carolina. The major mineral constituents of the ores were muscovite, quartz, kaolin, and minerals of the feldspar group. The ores also contained minor quantities of biotite, limonite, and tourmaline. A comparison of the specific gravities of the major constituents of the ores (muscovite 2.76 +, quartz 2.65, kaolin 2.61, and feldspar 2.57), indicates that an effective separation of muscovite from the other minerals can be made in heavy liquids at a specific

Jan 1, 1968

By Thomas Fraser, H. F. Yancey

The jig may be termed the standard coal-washing machine. Although exact figures on the relative tonnages of coal treated by the various coal-cleaning processes are not available, it is known that a large part of all the coal given special cleaning treatment is handled by jigs. This wide use of the jig warrants a special study of its performance. In this paper are presented the results of an analysis of work done by a three-compartment jig in treating bituminous coal from the Thick Freeport bed in Allegheny County, Pa. Certain systems of washing coal require sizing before washing, while others treat unsized coal. The prevailing practice, however, for the preparation of coking coal from the more easily washed coal is to treat an unsized or natural feed of about — 1 in. size and smaller. Under such conditions, the minimum size of particle that is beneficiated has long been and is still a matter of discussion and conjecture. In a careful laboratory investigation J?ngstl concluded that the practical limit of settling of fine coal is reached at from 0.02 to 0.008 in. On the other hand, Hancock2 has found that single-compartment jigs, used in preparing coal for the domestic market, usually allow most of the heavy (refuse) particles smaller than 1/4 in. to go into the washed coal. He also states that it is impossible with the ordinary coal jig to make any noticeable improvement in the quality of the coal finer than 20 mesh (about 1/30 in.). Because of its importance in coal cleaning, the work described in this paper was undertaken for the purpose of obtaining information on this subject, as a part of the general coal beneficiation program being carried out by the Bureau of Mines.

Jan 1, 1925

By David White

The submission of carefully prepared estimates of the oil reserves of the United States calls for no apology or explanation. In this country, petroleum is a rapidly wasting asset and an occasional appraisal of the amount remaining in the ground is a simple business procedure to safeguard the general welfare and the prosperity of the republic. The rumored danger of failure, in the near future, of the foreign supply on which we depend in constantly increasing amounts makes the immcdiatc review of our available reserves the more imperative. The Director of the U. S. Geological Survey, in March, 1921, requested the American Association of Petroleum Geologists to cooperate in the preparation of new estimates of the oil remaining in the graund. With the members of this cooperative committee, state geologists, regional geologists, oonsulting specialists, and geologists and engineers attached to many companies worked both independently and through subcommittees. The reports for districts, counties, fields, etc., after review by local or state committees, were discussed by the joint cooperative committee in conferences that, in some instances, were attended by the original compilers of estimates for the states or smaller areas. Finally the data were reviewed and the figures revised by the joint cooperative committee, so that the totals given in Table 1 represent the opinion of the committee, which was composed of F. W. DeWolf, W. E. Wrather, Roswell H. Johnsont Wallace A. Pratt, Alexander W. McCoy, Carl H. Beal, C. T. Lupton, G. C. Matson, K. C. Heald, W. T. Thom, Jr., A. E. Fath, Kirtley F. Mather, R. C. Moore, and David White, chairman. Oil geologists and engineers understand well the speculative nature and the chances of error that must attend estimates of the petroleum in the ground when they cover not merely prospective territory, but possible territory. Neither the character nor the magnitude of the factors of uncertainty is to be disguised. Further, the inevitable differences of opinion between geologists of equal rank and experience must also bc

Jan 1, 1923

By Alden B. Greninger

The study of mosaic structure of crystals1 has been confined until recently to the field of theoretical physics. Crystallographers, in general, have neglected the subject, although X-ray crystallographers constantly make use of formulas for intensities of X-ray reflection as modified by mosaic structure. Work on mosaic structure has centered chiefly on the task of proving or disproving the secondary-structure theory of Zwicky,² and very little attention has been paid to the visible imperfections of crystals. A. Goetz has been responsible for most of the supposed experimental confirmations of Zwicky's theory.3 On the other hand, Smckal,4 and Orowan,5 among others, maintain that there is neither theoretical nor experimental evidence to substantiate Zwicky's secondary structure. Lately the subject has been intensively investigated by Buerger,6 one of whose recent papers led to a symposium on mosaic structures.'

Jan 1, 1935

By Andrew Corry

GEOPHYSICAL investigations based on radioactivity have been applied to the earth's crust for the purpose of discovering bodies rich in radioactive substances, or for the location of solutions with high emanation or radioactive-salt content, or for the detection of oil, which, in virtue of colloidal properties, has strong powers of radioactive absorption. RADIOACTIVE SUBSTANCES Radioactive substances are distributed in all rocks, waters, and gases in the earth's crust in small quantities. Granites and similar acidic rocks are richest in uranium and thorium, two chief radioactive substances; yet the quantities present in such rocks are of the order 10-12g., this concentration being expressed in grams per gram of the whole substance per cubic centimeter. In granites the uranium yields, according to Haddock, 3 X 10-12 g. of radium per gram of rock. In basalts the uranium yields 1.19 X 10-12 g. per gram per cubic centimeter. Of thorium the granites yield -2 X 10-5 g. per gram of rock; the basalts, 0.77 X 10-5 g. per gram. Certain series of alkalis of low atomic weight, like potassium and rubidium, show weak radioactivity; this property has no significance so far for geological research. The uranium is esti-mated indirectly from the electrical properties of one of its derivatives as a -gas (emanation) into which it is transformed. The thorium is expressed directly, though it is measured as a derivative, thorium emana-tion. There is a measure for the gaseous radium emanation, the curie, which is that quantity of radium emanation, or radon, which stands in equilibrium with 1 g. of radium. The concentration of the emanation is the Mache unit corresponding to 3.64 X 10-10 curie per liter. When gases become permeated by alpha, beta, and gamma rays, plus and minus ions are produced in them by the decomposition of neutral gas molecules, and under the influence of an electrical field these ions are given opposite motions. The measurement of the alpha rays and the bisection thicknesses of the beta and gamma rays is a means of analyzing unknown radioactive substances. These rays accompany the disintegration of radioactive substances and arise from "spontaneous internal changes

Jan 1, 1929