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By Henry W. Edwards

Concrete is not a new, nor even a modern substance. Important structures built by the old Romans before the commencement of the Christian Era are to-day sound and solid— for example, the dome of the Pantheon in Rome, 142 ft. in diameter. I do not propose, therefore, to discuss the durability of the material, as in the mining and metallurgical business, structures, as a rule, are not calculated to endure for two thousand years. I do wish to urge, however, that much of the stone masonry around mines and smelters would have given better results if concrete had been used in place of stone. Concrete looks better; is stronger, cheaper, more durable, more quickly built, and above all requires no skilled labor, except that of the carpenter, who, like the poor, is always with us. Well proportioned concrete, that is to say, having well proportioned ingredients, may be safely relied upon to withstand a compressive or crushing strength of 50 tons per square foot. In most American cities, however, the building laws limit it to the absurdly low figure of 16 tons. This restriction is probably due to the political influence of the building-trades unions, which object strongly to its too free use, undoubtedly owing to its not requiring the services of skilled workmen. I hope to show that quite important construction work may be' undertaken without the aid of the gentleman with the trowel. In some of the isolated districts of the West and Southwest this is no mean advantage. The weight of good concrete, dry, is from 130 to 160 lb. per cubic foot. Ingredients of Concrete. Concrete is composed of four ingredients; viz., 1. Crushed Stone; 2. Sand; 3. Cement; and 4. Water.

Jan 1, 1905

By T. Sterry Hunt

THE geognostical relations of the metals and their ores present many problems of great interest, alike for the geologist, the chemist, and the mining engineer. The association with certain rock-formations of characteristic mineral species may help to guide the geologist in the identification of geological horizons, and throw light on the chemical activities which have been especially manifested in certain periods; while it is clear that such relations, if established, must be of great utility to the miner, and especially to the explorer of new regions. In inquiries of this kind, however, it is only by careful observations over wide areas, and by the collocation of a great number of facts, that anything like a safe basis for induction can be attained. The effects of hasty and imperfect generalizations in this field have already in many instances been felt to the prejudice of scientific progress. I come before you to-night, therefore, not to lay down any laws or general principles, but to call your attention to certain facts, many of them doubtless known to you, which have forced themselves on my attention, with regard to the associations of various metallic ores and other useful minerals with different series of stratified rocks, and to ask you to aid the progress of this branch of geognostical inquiry. Your observations in the various regions to which you may be called by your professional duties will enable you to determine how far these associations are mere coincidences, and how far they are chemical and geological constants. The associations here to be noticed concern only those mineral species which occur, either distributed through the strata in such a manner as to show that they are contemporaneous deposits, or occupy rifts or gash-veins in these strata, and may be supposed to have been

Jan 1, 1873

By T. Sterry Hunt

THE geognostical relations of the metals and their ores present many problems of great interest, alike for the geologist, the chemist, and the mining engineer. The association with certain rock-formations of characteristic mineral species may help to guide the geologist in the identification of geological horizons, and throw light on the chemical activities which have been especially manifested in certain periods; while it is clear that such relations, if established, must be of great utility to the miner, and especially to the explorer of new regions. In inquiries of this kind, however, it is only by careful observations over wide areas, and by the collocation of a great number of facts, that anything like a safe basis for induction can be attained. The effects of hasty and imperfect generalizations in this field have already in many instances been felt to the prejudice of scientific progress. I come before you to-night, therefore, not to lay down any laws or general principles, but to call your attention to certain facts, many of them doubtless known to you, which have forced themselves on my attention, with regard to the associations of various metallic ores and other useful minerals with different series of stratified rocks, and to ask you to aid the progress of this branch of geognostical inquiry. Your observations in the various regions to which you may be called by your professional duties will enable you to determine how far these associations are mere coincidences, and how far they are chemical and geological constants. The associations here to be noticed concern only those mineral species which occur, either distributed through the strata in such a manner as to show that they are contemporaneous deposits, or occupy rifts or gash-veins in these strata, and may be supposed to have been

By Robert Mehl

A STUDY of the structures arising from the decomposition of the a solid solutions in the Cu-Zn and the Cu-Al systems is of peculiar interest in the study of the mechanism of precipitation from solid solutions. It is possible in these alloys, by varying the composition within the ß field, to precipitate from the same basic lattice phases having different lattice structures. It has been rather generally assumed heretofore that the type of structure originating from the decomposition of a solid solution-the Widmanstätten structure-is determined by the lattice structure of the parent solid solution alone. In the first paper of this series1 evidence was advanced which threw doubt upon this hypothesis; but definite proof of the correctness or incorrectness of the hypothesis should be forthcoming from a study of these alloys, for if the structures originating, for example, from the precipitation of the a phase from ß and of the -y phase from the ß in the Cu-Zn system should be shown to be crystallographically different, the hypothesis would necessarily be held as definitely disproved. Furthermore, the newer proposal enunciated in the first paper of this series-that the origin of the Widmanstätten structure lies in a cooperation between the lattice of the parent solid solution and that of the precipitate-which at present seems the only alternative hypothesis, would in such an event be given added weight. The work here reported shows that the Widmanstätten structures originating in the precipitation of the a phase from the a and in the precipitation of the -y phase from the ß in the Cu-Zn system are indeed crystallographically different; and incidentally presents some new descriptive information on the Widmanstätten structure from a more general point of view.

Jan 1, 1931

A price list of publications of the Geological Survey, complete to May, 1931, and with separate monthly notices of publications to (late, will be sent upon application to The Director, United States Geological Survey, Washington, D. C. A leaflet is issued each month listing new publications; it will be sent upon application to the Director, as well as Circulars containing information about topographic maps. Book publications of the Survey include (1) Annual Reports, (2) Monographs, (3) Professional Papers, (4) Bulletins, (5) Water Supply Papers, (6) chapters and volumes of Mineral Resources of the United States, (7) Folios of the Geologic Atlas of the United States and the World Atlas of Commercial Geology, (8) Topographic Folios and Topographic Maps that bear descriptive texts. Monographs, Folios of the Geologic Atlas of the United States and the World Atlas of Commercial Geology, and Topographic Folios and Topographic Maps, are not distributed free. A publication of one of the other classes can be distributed free only until the end of the fiscal year following that in which it was issued. No person can obtain more than one free copy of the same publication, and general requests for free publications, such as all of any series or all on any subject, can not be granted. In ordering publications one is requested to give both the series designation, as Bulletin 738 or Professional Paper 122, and the title. Give full address, plainly written, including county. Prepayment is required and may he made by postal, or express money order payable to the official charged with the sale of the publications. requested, as indicated in the discussion of each classification following; or it may be made in cash-exact amount -at sender's risk. Postage stamps are not accepted in payment for publications.

Jan 1, 1933

By John Pew

PRIOR to the development of the bulk-oil carrier, practically all transportation of oil was in barrels and in cans contained in wooden cases; the latter was known as case oil. In the year 1885, approximately two hundred million gallons of petroleum were exported from this country in barrels and about one and three-quarter millions in bulk; less than twelve years later, the shipment in barrels had decreased to nearly one and three-quarter million gallons, while the transport of bulk oil had increased to four hundred eighty-four million gallons. The first modern tanker, the "Glückauf," was built in England in 1886. Her hull, which was 300 ft. long, was divided into compartments by transverse bulk-heads, these compartments being divided by longitu-dinal center-line bulkheads extending throughout the oil spaces. There was a pump room forward of the boiler room, thus providing a cofferdam or safety space. Between the main and upper decks, a narrow trunk extended the full length of the' oil spaces, the trans-verse and longitudinal bulkheads being carried to the upper deck. This allowed for the expansion of the oil from a rise in temperature, and if the tank below the main deck was kept full, the danger of the oil moving with the roll and pitch of the vessel was considerably reduced. Spaces for the carriage of light oil were provided on each side of the vessel outboard of the expansion trunk, while water ballast was carried under the machinery compartments fore and aft. Although vessels previously had been built to carry oil next to the skin of the ship, it is claimed that the "Glückauf" was the first one constructed on the new principle outlined.

Jan 12, 1922

By Robert Kinzie

WHEN Mr. Cameron, the President of the Santa Cruz Portland Cement Co., returned from Europe in 1929, he brought first-hand infor-mation about a very versatile type of hydraulic cement. It was not a new cement, many articles having been written about it in foreign journals, but in this country the record of this type of cement had been either neglected or minimized. Using local materials, and applying the information brought back by Mr. Cameron together with many data in numerous publications, the Santa Cruz Portland Cement Co. developed the Santa Cruz high-silica cement. This cement is manufactured by grinding with portland cement clinker a properly calcined mixture of siliceous material and lime. It has all the utility of portland cement, together with an increased resistance to the destructive action of many aggressive solutions. To explain the necessity for the development of a cement having these characteristics, the history of hydraulic binding materials may be reviewed briefly. The materials used as binding media by primitive people were mud, lime, gypsum and bitumin. Due to its utility, ease of preparation, and its common occurrence, lime was the most widely used. Fat lime, when used by itself or with an inert sand, hardened only on the outside surface, where the carbonate was formed by absorption of carbon dioxide from the air, while, the interior of the mortar remained soft. It was quite early discovered that the incorporation of proper siliceous material with the lime increased its ability to harden, and for this purpose various natural siliceous powders were used, such as puzzo-lana in Italy, trass in what is now Germany, and santorin in Greece. These powders reacted with the lime forming a permanent cement and rendered unnecessary the access of carbon dioxide to the mortar.

Jan 1, 1934

The official Institute reports for the year 1929 were distributed in pamphlet form at the Annual Meeting, February, 1930, and were later included in Section 2 of Mining and Metallurgy, June, 1930, and thus made available to the entire membership. Membership In its report the Admissions Committee set forth the changes in membership during 1929, as follows: Total membership, Jan. 1, 1928, 8582; elected and placed on rolls in 1929, including 59 reinstatements, 509; loss by resignations in 1929, 88; loss by death in 1929, 110; loss by suspension in 1929, 37; membership at end of year not including Student Associates, 8856. Distribution of membership: Honorary Members, 16; Members, 6590; Junior Members, 38; Associates, 1041; Junior Associates, 1033; Rocky Mountain, 138; total membership, Jan. 1, 1930, 8856; Student Associates, 150; total including student associates, 9006. Treasurer's Annual Report, Year of 1929 Statement of Receipts For the year ended December 31, 1929 Dues: Arrears............................................ $ 3,501.75 Current............................................ 97,257.12 New Members...................................... 5,721.50 Advance........................................... 1,970.79 $108,451.16 Initiation Fees.................................................. 7,436.OO Magazine Receipts: Advertising Gross Receipts........................... $40,610.81 Magazine Sales..................................... 3,799.84 44,410.65 Sale of Transactions Current........................... $ 2,985. 15 Sale of Special Editions Current........................ 5,147.82 Sale of Back Transactions and Special Editions........... 4,186.93 Sale of Year Book..................................... 65.50 Sale of Authors' Reprints.............................. 2,585.40 Sale of Pins and Fobs.................................. 14.73 Sale of Technical Publications.......................... 1,451.55 Sale of Bindings...................................... 3,949.13 20,376.21 Net Interest Received: On Bank Balance and Temporary Investments......... $ 2,595.04 On Lie Membership Fund........................... 3,223.43 On James Douglas Library Fund...................... 5,425.61 On General Reserve Fund............................ 2,015.58 13,259.66 Miscellaneous Receipts........................................... 335.80 Total Receipts................................................ $194,269.48

Jan 1, 1930

By K. L. Williamson, P. W. Dugan

INTRODUCTION In recent years there has been increased social awareness and government attention directed toward the mining industry. The growing influence of the Occupational Safety and Health Administration (OSHA), the Mine Safety and Health Administration (MSHA), and the Environmental Protection Agency (EPA) has resulted in volumes of regulations governing a multitude of health and safety aspects of mining and milling. These regulations naturally have had an impact on new plant design and in some cases have necessitated retrofitting of existing plants. This paper will not examine the regulations governing the industry, since they are a matter of public record, but rather will address two specific health considerations, dust and noise, and their influence on the design of crushing and screening plants. DUST AND NOISE CONCEPTS Dust is generally defined as finely divided solids which may become airborne without any physical or chemical change except fracture. Since the purpose of comminution circuits is to reduce the size of solids by fracture, a percentage of the material is normally reduced in size to a point where it can easily become airborne. The major cause of dust becoming airborne is the air induced by falling material. When granular material falls through a distance, the induced (or entrapped) air rushes out available openings, carrying with it the fine particles that have become suspended. For this reason, the major points of dust generation are the points where the material is falling: chutes, transfer points, screens and equipment feed and discharge points. The expected dust concentration in an area is a function of the degree of size reduction (i.e., finer particles are more readily carried by air currents than heavier particles) and the volume of air that is induced. The measured dust concentration values for various operations agree with this

Jan 1, 1982

An Outline Classification of Mining Systems for Ore and Coal. See COAL Progress at the Homestake Mine. By Guy N. BJORGE. (Min. & Met., June, 247. 4400 words.) Homestake's mining methods today are controlled to a con¬siderable extent by that which has been done in the past. The two main operating shafts were begun m 1878 and 1896 respectively, so that the location of shafts, loca¬tions of all the drifts on the upper levels, and a great deal of stoping was done before any of those now connected with the mine had anything to do with it In this paper is described the general plan of development. A table shows percentage of total production mined by the different methods in recent years. Average daily produc¬tion for several years now has been about 3850 tons milled. With the present schedule of 6-day operation of the mine, that means about 4450 tons a day mined This ore is treated at three plants, with respective capacities of 2000, 1200 and 600 tons The principal novelty in milling is at the largest mill where the stamps are used as crushers only, and where in the last two years a notable increase has occurred in the size of screens used A unit has been added to cyanide plant No 3 The construc¬tion of a new shaft is described, as is also the hoist building The company operates its own lumber and timber department It has a well equipped hospital Housing at Lead is an individual matter. Rejuvenating the Golden Chariot Property in Idaho. By R. S. MCCLELLAN (Min. & Met, November, 443. 2300 words) An effort to rejuvenate the Golden Chariot group of properties near Silver City is now being carried on by the John Hays

Jan 1, 1935

By James R. Cudworth, Joseph C. Mead

The Birmingham district of Alabama has utilized the slag from its blast furnaces consistently since the earliest development of the slag industry. Today there are producers of slag cement who started business in 1900, and who have, under a progressive policy, expanded the number of their products to meet present demands. There are producers of slag aggregates and other crushed slag products who have been successful for periods of over thirty years. There are at the present two companies, Cheney Lime and Cement Co. and the Southern Cement Co., manufacturing puzzolan cement; two companies, Birmingham Slag Co. and Woodstock Slag Co., making slag aggregates and by-products; one company, Tennessee Coal, Iron and Railway Co., a subsidiary of the U. S. Steel Corporation, producing ground open-hearth basic slag for soil conditioning. Two companies, the Sloss Sheffield Steel and Iron Co. and the Woodstock Slag Co., make slag concrete in ready-mix plants and one company, the Superock Company, manufactures fine and coarse slag aggregates under a new granulation process. NO Portland cement is made with slag as an ingredient, because dolomite is used so extensively as a blast-furnace flux that the magnesium content of the slag is excessive. Sources of Slag In the Birmingham district there are 22 blast furnaces, of which the majority are in blast. The present production is 165,000 tons of pig iron monthly; the production in 1935 was 1,297,960 gross tons1. There arc also two blast furnaces at Gadsden and one ferroalloy electric furnaee at Anniston. From these two sources is obtained slag to approximately 1.1 tons per ton of pig iron. History of Development of the Industry The history of the local utilization of slag as an industry probably starts with the Birmingharii Slag Cement Co. This company was

Jan 1, 1938

By Joseph C. Mead, James R. Cudworth

The Birmingham district of Alabama has utilized the slag from its blast furnaces consistently since the earliest development of the slag industry. Today there are producers of slag cement who started business in 1900, and who have, under a progressive policy, expanded the number of their products to meet present demands. There are producers of slag aggregates and other crushed slag products who have been successful for periods of over thirty years. There are at the present two companies, Cheney Lime and Cement Co. and the Southern Cement Co., manufacturing puzzolan cement; two companies, Birmingham Slag Co. and Woodstock Slag Co., making slag aggregates and by-products; one company, Tennessee Coal, Iron and Railway Co., a subsidiary of the U. S. Steel Corporation, producing ground open-hearth basic slag for soil conditioning. Two companies, the Sloss Sheffield Steel and Iron Co. and the Woodstock Slag Co., make slag concrete in ready-mix plants and one company, the Superock Company, manufactures fine and coarse slag aggregates under a new granulation process. NO Portland cement is made with slag as an ingredient, because dolomite is used so extensively as a blast-furnace flux that the magnesium content of the slag is excessive. Sources of Slag In the Birmingham district there are 22 blast furnaces, of which the majority are in blast. The present production is 165,000 tons of pig iron monthly; the production in 1935 was 1,297,960 gross tons1. There arc also two blast furnaces at Gadsden and one ferroalloy electric furnaee at Anniston. From these two sources is obtained slag to approximately 1.1 tons per ton of pig iron. History of Development of the Industry The history of the local utilization of slag as an industry probably starts with the Birmingharii Slag Cement Co. This company was

Jan 1, 1938

By John T. Galey

In all, 210 wellst were completed in southwestern Pennsylvania during 1939, which is 59 more than were drilled during the preceding year. Of this number, 137 were gas wells, which is a considerable increase from the 81 completed during 1938. Only 25 oil wells were completed, as against 28 in the previous year, and 28 dry holes, 6 more than last year. Shallow Development—Gas The increase in the number of gas wells is largely the result of a search for additional gas in Armstrong and Indiana Counties. Although a considerable number of wells were drilled in the latter county, the majority of them produced less than 100 M cu. ft. initial open flow. In Armstrong County, a new pool was opened in Cowanshannock township, producing from the third Bradford sand. Several large wells were obtained there, one of which produced an initial of nearly 12 million cu. ft., with a reservoir pressure of 1100 Ib. However, the productive area has been fairly well outlined by further drilling and shows that the pool covers only about 800 acres. The sand is 20 to 30 ft. thick, and probably has 5 to 6 ft. of pay. Thus this reserve is not an important one. Several wells were found in Menallen township, Fayette County, where the Big Injun sand has been having a play for the past three years, but the activity there is much less than a year ago. Oil On the west side of the Bradford sand gas pool, Cowanshannock township, Armstrong County, a well was drilled which flowed 100 bbl. the first day from the Tiona sand. The probability is that this well is a freak, as the Tiona has been drilled within a fairly close distance on every

Jan 1, 1940

Present indications are that the Fourth National Exposition of Chemical Industries, to be held in Grand Central Palace, New York, Sept. 23 to 28, will be the greatest exhibition of its kind ever held. Preparations are well under way and the advisory committee is working hard to make, every department of the affair a success. Men prominent in the chemical and allied industries will speak on subjects vital to present conditions and needs. Dr. C. H. Herty, and Dr. G. W. Thompson, President of the American Institute of Chemical Engineers, are to make opening addresses. F. J. Tone, President of the American Electrochemical Society; Dr. W. H. Nichols, President of the American Chemical Society, and several others, are expected to make addresses also. Prof. Joseph W. Richards will speak on : ?Ferro-alloys of silicon, tungsten, uranium, vanadium, molybdenum, and titanium." Theodore Swann, President of the Southern Manganese Corporation will speak on "Ferro-manganese." The program for the exposition is in active preparation. There will be a series of symposiums on the "Development of Chemical Industries in the United States, notably since July, 1914." Among other topics for consideration is that of potash development; C. A. Higgins, of the Hercules Powder Company, will speak of the operations of that company in the recovery of potash from kelp; Linn Bradley, of the Research Corporation, on its recovery from cement dust, and other sources, by electrical precipitation. Other symposiums will be devoted to chemical engineering, acids, industrial organic chemistry, the ceramic industries, and the metal industries. Among the speakers are: A. Hough.-" Chemical Engineering in Explosives: TNT; TNA; Picric Acid; and Nitrobenzol." E. J. Pranke.-" Development of Nitric Acid Manufacture." S. P. Sadtler.-"Development of Industrial Organic Chemistry." Geo. H. Tomlinson.-" Wood as a Source of Ethyl Alcohol." C. A. Higgins.-"Kelp as a, Source of Organic Solvents." Alcan Hirsch.-" Pyrophoric Alloys."

Jan 9, 1918

By John T. Galey

In all, 210 wellst were completed in southwestern Pennsylvania during 1939, which is 59 more than were drilled during the preceding year. Of this number, 137 were gas wells, which is a considerable increase from the 81 completed during 1938. Only 25 oil wells were completed, as against 28 in the previous year, and 28 dry holes, 6 more than last year. Shallow Development—Gas The increase in the number of gas wells is largely the result of a search for additional gas in Armstrong and Indiana Counties. Although a considerable number of wells were drilled in the latter county, the majority of them produced less than 100 M cu. ft. initial open flow. In Armstrong County, a new pool was opened in Cowanshannock township, producing from the third Bradford sand. Several large wells were obtained there, one of which produced an initial of nearly 12 million cu. ft., with a reservoir pressure of 1100 Ib. However, the productive area has been fairly well outlined by further drilling and shows that the pool covers only about 800 acres. The sand is 20 to 30 ft. thick, and probably has 5 to 6 ft. of pay. Thus this reserve is not an important one. Several wells were found in Menallen township, Fayette County, where the Big Injun sand has been having a play for the past three years, but the activity there is much less than a year ago. Oil On the west side of the Bradford sand gas pool, Cowanshannock township, Armstrong County, a well was drilled which flowed 100 bbl. the first day from the Tiona sand. The probability is that this well is a freak, as the Tiona has been drilled within a fairly close distance on every

Jan 1, 1940

By J. A. M. van Liempt

Since the discovery of von Laue, that a crystal forms a natural grating for X-rays, our knowledge of the structure of solids has gone forward with rapid strides. This progress is not only of purely scientific interest, but has also yielded direct technological results. One of the most valuable results is the broadening of our knowledge of the structure of pure metals and alloys. To promote these studies it is often desirable to have at our disposal pieces of metal consisting of one single crystal. As is so often the case in the natural sciences, we obtain the best results by making our earliest experiments on pure, simple materials and avoiding unnecessary complications. The Cryogen Laboratory at Leyden followed this method with much success, because the work was done at such low temperatures that the heat movement of the atoms was almost absent. Similarly we can simplify the studies of metals by leaving out of consideration the influence of the grain boundaries and the mutual influence of the crystals by using unicrystalline instead of polycrystal-line metal. Methods of making single crystals have been scientifically studied during the past few years. Some methods were already known in the arts, but these have been improved and new methods have been developed. The methods for making metallic single crystals may be divided into the following groups: A. From the liquid state B. From the gaseous state C. Electrolytically D. By recrystallization in the solid state Method A 1. Tamwmnn's Method1—Tammann succeeded in making bismuth single crystals of a maximum length of 20 cm. by undercooling the molten metal 0.1 to 0.3' G. below its melting point in glass tubes of a maximum

By Will H. Coghill

In this investigation, the low-grade red iron ores of Alabama were examined by the use of "heavy solutions."' Ores are generally ground preparatory to concentration and as long as the concentrators make suitable products the effectiveness of the grinding is likely to be unquestioned; but when suitable products are difficult to make, an investigation becomes imperative. In such a case a dissection of the ore might be made to find the cause of the trouble. Such a condition of unsuitable products exists in the low-grade red iron ores of Alabama. They are difficult to concentrate. To be sure it might be said that the concentration of iron ores is a new thing and that the ore-dressing methods are undeveloped, but a glance at the industry reveals an abundance of methods and devices for almost all imlaginable conditions. Concentrating machinery has not been tested in this investigation. When the properties of the ores have been gleaned, the machinery may be used more effectively. Alabama Low-grade Red Iron Ores The Bureau of Mines has undertaken by laboratory methods to select the best means of concentrating the low-grade iron ores of Alabama. These ores constitute the parts of the ore bed left by selective mining. If more of the ore bed could be included in the current output, the mining cost would be reduced and longer life of the district would be insured. This advantage would be reflected by added permanence of churches, homes, schools and every undertaking in the commonwealth. The red ores chosen for this study of effectiveness of grinding are too low in lime to meet the requirements of the blast furnace. If lime is

Jan 1, 1927

By Guido Del Giudice

THE term "slime-coating" is not new in the art of flotation; the phenomenon has been observed and described by Taggart;(1)? Taggart, Taylor, and Ince;(2) and by Ince.(3) Notwithstanding that flotation was introduced for the treatment of finely crushed ore, the adverse effects of slimes have been recognized since the earliest days of the process, and the Elmore, Delprat, Potter, and other processes actually specified desliming of the ore prior to treatment. The cause of this trouble has been studied and described by Taggart;(1) Taggart, Taylor, and Ince;(2) Ince; 3 Morrow and Griswold;(4) and by Gaudin and Malozemoff.(5) OLD THEORY OF SLIME-COATINGS At present, so far as published work shows, there seems to be but one theory for the mechanism of slime-coatings. Ince(3) states that they are due to attraction between electrostatic charges of opposite sign on the sulfide and, on the slime particles, supporting this theory by migration experiments in the Burton tube. He also used the microscope in conjunction with a glass cell employed by Beans and Eastlack(6) in studying migration, but met with interference from endosmosis. Several attempts have been made in the Department of Mineral Dressing at Columbia University to duplicate Ince's experiments with the Burton tube, but the results have never been convincing. Formation of precipitates which settled through the pulp levels, and evolution of gas at the electrodes, which disturbed the interface between the pulp and the distilled water above it, seriously interfered with observations. However, by use of the migration cell shown in Fig. 1, endosmosis effects and the disturbances due to precipitation and gas evolution were avoided, and distinct and reproducible migrations or absence of migration were observed.

Jan 1, 1934

By C. H. Mathewson

BeRyllium, magnesium, zinc and cadmium, together with mercury, constitute a coherent sub-group of the periodic system and these metals, excepting mercury, have been studied in sufficient detail by the new X-ray diffraction methods to prove their common adherence to the hexagonal close-packed type of crystal structure with a progressive increase in axial ratio as we pass through the group from beryllium to cadmium. The first four columns of Table 1 summarize the data on crystal structure of these metals reported in the International Critical Tables.' The last two columns are based on results obtained in the present investigation. Twinning has often been observed in zinc and cadmium. The general aspects of this twinning are abundantly illustrated by photomicrographs, diagrams, etc., in the papers by Romig, and Mathewson and Phillips reported to this Institute in 1927.2 A determination of the composition

By William F. Boericke

THERE was a time when the selection of fire brick was .left to the judgment of the head bricklayer of the plant, whose choice was not unaffected by a box of Christmas cigars from a friendly salesman. But the days are past when it was generally believed, with complacent philosophy, that bricks were bricks without much distinction, and should be bought on a price basis alone. Gone, too, is the belief that in certain types of industrial work the eventual failure of refractories was assured. Modern metallurgical practice, with its trend toward handling larger tonnages at higher temperatures, demands the use of refractories that cannot be supplied by random guess. The logical development is to inquire into the properties of the brick to be purchased, and this resolves itself into the use of specifications. In 1925, the General Refractories Co., with the active support and hearty cooperation of some of its larger customers, established a laboratory, at its Baltimore plant, for testing and research in refractories. This was the outgrowth of a growing appreciation of the value of research in the refractory field. Since then the work has become more involved' and the aims more ambitious, so that the present laboratory now employs a staff of 11 men working, under the direction of trained refractory technologists, on problems of research as well as the routine control of manufacture. It is believed s that `this type of laboratory is a comparative novelty among refractory manufacturing plants. It handles the testing and research work for all the 15 plants of the organization. Being at one of the works has the advantage of making it possible to carry on large scale plant tests on new products after the preliminary laboratory tests have been successfully completed.

Jan 1, 1929