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[MUNOZ, P.: New Oil Fields in Trinidad, M27, 311 MUNRO, C. H., biography, M84, 354 MUNROE, H. S., biography, M83, 277 Muntz metal (See also 60:40 Brass): corrosion. See Corrosion of Metals. fatigue and corrosion-fatigue, 78, 597 heat-treated: cleavage structure, 83, 498, 505 grain growth, abnormal, 83, 503, 505 machinability, 99, 323 stress-corrosion cracking, 89, 249. 266 MURAKAMI, T.: iron-silicon diagram, 80, 253, 255 MURDOCH, J. A. W., biography, M28, 157 MURDOCK, W. J.: Discussion on Adaptability of Various Coals as Generator Fuel in Manufacture of Water Gas 78, 561, 565, 566, 568 MURPHY. D. W. AND CHIPMAN, J.: Solubility of Nitrogen in Liquid Iron (T.P. 591) 116, 179. Abs., YB35, 33; M35, 114 MURPHY, L. J.: Relative Advantages and Costa of Electric Power in Lease Operations 77, 219]

Jan 1, 1936

By Donald Barton

THE purpose of this torsion balance survey and the quantitative calculations was to delimit the extension of the cap rock at the Hoskins Mound salt dome. The sulfur ore in the Gulf Coast sulfur-bearing salt domes occurs in the lime rock, which is the outer layer of the cap-rock mass, and also in the underlying gypsum zone. The status of the exploration and exploitation of the Hoskins Mound dome at the date of this survey is shown by Fig. 1. The mound had been covered by the very early prospect wells of the Mound Oil Co., and the later and more numerous prospect wells of The Texas Company. The Freeport Sulphur Co. was producing from the flank wells in the southwest quadrant. The limits of the cap were surmised to lie inside the centers of quad-rangles 4F, 3F, the center of the NE. ¼ of 2E, and the north line of 2D. That surmise was based partly on the data of Fig. 1 and partly on the position of the edge of the topographic mound. The management of the Freeport Sulphur Co. wished to block out the extent of its ore reserves with a minimum of expenditure. The management was informed by the writer that no geophysical method could map the presence or quantity of sulfur directly, or determine the presence and quantity of the lime-rock cap independently of the rest of the cap, but that a reasonable probability existed that the approximate position of the edge, the depth and the thickness of the cap-rock mass as a whole could be determined through quantitative calculations based on the data of a very careful torsion balance survey. Considerable lime rock would probably be present, of course, wherever much cap rock was present. This paper presents the data of the survey, our calculated prediction of the configuration of the cap rock, and the degree of confirmation by the subsequent drilling. The survey was made by the Geophysical Research Corporation, under the direction of the writer. The work of the calculations was done by Andrew Gilmour, then assistant to the writer.

Jan 1, 1936

By N. O. Johnson

This is one of a series of-Information Circulars dealing with mining and milling methods and costs at mines in various districts in the United States. The Hog Mountain gold mining district is of the northern edge of Tallapoosa County, in the east central part of the State of Alabama. The district is equally close to Goodwater and to Alexander City, both stations on the main line of the Central of Georgia Railroad. From Alexander City the mine is reached by 13 miles of graded road, traveling in a northeast direction. In dry seasons the road is good; in wet weather it is bad but passable. Improvements are being made constantly on the road, so that in the near future the gravel road should be good under all weathered conditions.

Jan 1, 1936

By L. W. McKeehan, W. C. Elmore

The magnetic powder method, long used for roughly mapping magnetic fields, has recently been refined1, "or investigating the microscopic variations in the surface magnetization of ferromagnetic crystals. Bitter2 first discovered regular powder patterns connected with the crystal structure of such specimens. Several other investigators:' have used Bitter's original technique, with slight modifications, to study the variation of the patterns with variations in the magnetizing field applied parallel to the surface, and their dependence upon the state of strain, of polish and of crystal cut. All of the explanations of these patterns on metallic ferromagnetics have been couched in general terms. In a preliminary report we have described an improvement ill the powder technique which led us to the discovery of a new effect throwing considerable light on the magnetic secondary structure of alpha iron4 and of nickel5 single crystals. We now report additional evidence confirming the existence and stability of a magnetic block secondary structure. Specimens The following list describes the specimens used in the present investigation. Designation Description A1 Silicon ferrite furnished to us by Dr. W. E. Ruder, of the General Electric Co., for which lie gave the following typical analysis: C, 0.05; P, 0.038; S, 0.026; Mn, 0.15; Si, 3.24. Disk, 0.60 cm. diameter, about 0.05 cm. thick. By X-ray analysis angles between disk normal and [100] 75o, [0101 76" [00l] 21o. A2 Same as A1 except: diameter 0.75 cm. A, Same as A1 except: diameter 0.68 cm.

Jan 1, 1936

By Emory Kemler

The problem of determining the most desirable operating conditions of an oil-well pumping unit, the selection of the proper material and size of sucker rods, and the design of the pumping unit, requires that the sucker-rod loads be known with a reasonable degree of accuracy. In production practice, it is also desirable to know the effects of operating speeds and strokes on a plunger motion, as well as on the rod loads. For a particular well, data on rod loads can be obtained by measuring the load in sucker rods with a dynamometer. This method is not satisfactory because it does not permit the various factors to be investigated independently. It is also impossible to measure the plunger motion simultancously with rod motion under operating conditions. The mathematical solution is impractical because of the simplifications that have to be made to get a solution and the tremendous amount of numerical work that is necessary after such a simplified solution has been attained. This paper shows how analogies and models can be applied to the solution of these problems. The loads set up in a sucker-rod string during the ordinary pumping cycle are made up of the weight of the rods, force required to accelerate the rods, weight of the oil and force required to accelerate the oil on the upstroke, rod friction, stuffing-box friction, plunger friction, friction of the oil in the tubing and rods, arid friction loss through the valves. The problem of determining the sucker-rod load is further complicated by the fact that the long oil column and the sucker-rod column act as springs, which affect the transmission of the polished-rod motion. A further complication is the fact that the motion cannot be transmitted at a speed greater than that of the velocity of sound in the material, and this means that there will be a time lag in the transmission in the motion, as well as a modification of its magnitude and a phase displacement.

Jan 1, 1936

By D. Harrington

Probably over 95 percent of the coal production of the United States depends upon the use of explosives before it can be placed in the railroad car at the mine, and up to the present time it has been impossible to obtain Pry kind of practicable explosive that isn't dangerous unless handled carefully. In other words, no "foolproof" explosives have been found to date and inspection of the accident records of the coal mines of this country indicates that the use of explosives in coal mines has taken a sad toll of lives. ACCIDENTS PROM EXPLOSIVES IN COAL MATES Of the 2,000 to 2,500 persons killed annually in the coal mines if the United States, 100 to 125 have been killed from explosives without an explosion of gas or dust; these accidents have been due to misfires, hangfires, premature blasts, or accidental setting off of explosives through carelessness or otherwise (but chiefly through carelessness in some form). In this type of accident the flame character of the explosive is not necessarily involved, although an unexpected or premature blast is initiated much more easily with black blasting powder, which has a long flame, than with a permissible explosive, which has a flame much shorter and of briefer duration. By far the greater number of such accidents are caused by black blasting powder or dynamite rather than by permissible explosive.

Jan 1, 1936

By George S. Rice

In response to numerous requests for information as to the status of internal-combustion mine locomotives of the Diesel type that use heavy or nonvolatile oil for fuel, with special reference to their safe use in coal mines, the United States Bureau of Mines is issuing this t port. Data were obtained on application of such locomotives to coal mining only in Belgium, France, Germany, and Great Britain. The locomotives are used in coal mining in other countries, as well as in potash, iron, and other kinds of mining, but their chief development has been in coal mining in Germany, France, and Belgium. Recently popular interest in the Diesel type of engine for motive purposes was aroused in this country by the successful application of Diesel engines to railroad locomotives hauling fast transcontinental trains, and, according to published statements, at a low cost of fuel per mile of run.

Jan 1, 1936

By William C. Schulte, Gilbert E. Doan

An extensive program of investigation is being carried out at Lehigh University in the study of arcs and arc welds of high-purity iron1, sponsored by the Engineering Foundation. The part of that program reported in the present paper deals with welds made of high-purity iron in an argon atmosphere and for comparison with them welds made of the same iron in ordinary air. Welds of commercial steel also were made in argon and in air. The primary purpose of the study is to discover the basic physical constants of iron welds when not contaminated either by impurities in the iron or by the action of oxygen and nitrogen of the air during welding. Upon these constants can be founded such future studies as will determine what effects the various impurities and alloy elements present in steel have upon its welding characteristics, and what influence is exerted by the action of oxygen and nitrogen. The welding of steel involves such a multitude of variables, both of composition and of procedure, that development in the fabrication of this most important metal has necessarily been slow, wasteful, and in many instances discouraging. In the present investigation, the simplest possible condition has been selected; namely, iron practically free from contamination and a nonparticipating atmosphere, the inert gas argon. This simplification reduces the number of variables to a point where more rigid control of the system is possible. Although this study is significant for the contributions it makes to the science of steel fabrication, yet it is hoped that it will not be without value also in increasing knowledge of the. nature and behavior of iron and steel in general. From the standpoint of open-hearth practice, and to some extent from the standpoint of electric-furnace practice also, the conditions of melting and casting iron in this investigation are extraordinary. The casting temperature is high, the mean temperature of the metal probably reaching 2000' C. (3600' F.)? The rate of chilling of

Jan 1, 1936

By Eric Sinkinson

MANY of the magnesite ores of the western part of the United States contain such large amounts of silica and hydrous silicate minerals that the value of the ores is either low or nominal. Expensive and carefully controlled mining methods are necessary to prevent excessive dilution of the higher grade ores by introduction in mining' of small pieces of the hanging walls or footwalls of the deposit. This difficulty is further complicated by the various states of decomposition of the country rock of the deposits in which many of the ores occur. The problem the authors attempted to solve arose from a request to float an impure magnesite containing varying proportions of siliceous gangue with calcium carbonate. The ore is normally. enclosed in serpen-tine masses, somewhat decomposed, and in mining it wall rock is inci-dentally added, so that variable amounts of siliceous material occur in the samples. The silica, alumina, and iron oxide are so closely associated with the magnesium carbonate in the magnesite that ordinary mechanical separation at coarse mesh sizes is of no avail. It is well known that calcium carbonate can be floated by suitable reagents, therefore it seemed reasonable to suppose that magnesium carbonate minerals would behave in a similar manner, but experimental trial proved that this supposition was unfounded. Therefore the first step in the problem was to find out what differences of behavior there were between magnesium and calcium carbonates under flotation conditions, or when suspended in water. In water at 18° C. magnesium carbonate is slightly more soluble than calcium carbonate; in fact, MgCO3 is soluble to the extent of 0.0106 grams in 100 c.c. of water at 18° C. and CaCO3 to the extent of 0.0013 grams. However, magnesium carbonate in water gradually changes to the basic carbonates of a composition (3MgCO3.Mg(OH)23H20) or (4MgCO3.Mg(OH)25H20), depending upon conditions, and calcium carbonate to calcium hydroxide, Ca(OH)2, The relative solubilities of these hydroxides in water are the reverse of the solubilities of magnesium and calcium carbonates.. The range in published figures for solubility

Jan 1, 1936

By M. Albertson

The purposes of this statement are to define a problem that exists in regard to the estimation of developed petroleum reserves, to analyze the problem in an abstract manner, and to discuss it as an introduction to certain papers that follow. The problem is to devise and develop a suitable procedure to permit more accurate estimates of developed petroleum reserves. Part of the problem is to make such estimates available earlier in the life of any particular pool. The problem of securing more accurate estimates of developed petroleum reserves existed prior to curtailment of production. With curtailment, however, the problem became acute, some of the more prominent reasons being as follows: 1. The standard method of estimation depended on production-decline curves. This method is inapplicable while curtailment prevails and available methods arc insufficient. 2. The retarding influence imposed by wide open flow conditions upon overdevelopment is absent. Great losses of capital by overdevelopment can now occur before realization of the true situation occurs, or before effective steps can be taken to stop such wastage. This increases the need for early, accurate estimates. 3. Above-ground stocks have diminished and the equivalent of such supply tends more and more to be retained underground in the natural reservoirs. It becomes increasingly necessary to know accurately the amount of these stocks. To direct attention to an additional point of different nature: improved accuracy of reserve estimation can be obtained only by closer scrutiny of the factors that determine recovery. This examination and the resulting efforts to measure the effect of these factors in terms of ultimate recovery must tend to improve ultimate recovery. The statements regarding the acute nature of the problem also indicate to some extent the importance of the problem and the necessity of finding a solution. Developed reserves of the industry, and of individual opera-tors, are one of the great factors that properly should determine explora-

Jan 1, 1936

By J. L. Rodda, R. L. Wilcox, E. C. Truesdale

In recent years various problems in connection with research work on the preparation and properties of zinc-base alloys have required reliable information concerning the constitution of the zinc-rich portion of the iron-zinc equilibrium diagram. On numerous occasions rather positive indications were obtained that, for example, the solubility of iron in zinc was incorrectly represented on the current equilibrium diagrams. A careful study of all the available literature relating to the iron-zinc system led to the conclusion that much of the early work was unsatisfactory as measured by present standards of experimental accuracy, and as a result it was decided to redetermine the location of the liquidus curve and of adjacent portions of the diagram. Part I of this paper comprises a description of the experimental methods and a summary of the results by means of which the zinc-rich end of- the iron-zinc diagram has been revised in the following ways: 1. Measurements of the solubility of iron in liquid zinc by several different sampling methods, leading to a relocation of the liquidus curve. 2. Microscopic, conductivity, and X-ray studies of the solid solubility of iron in zinc, which, together with thermal analyses, have resulted in new values for the solid solubility and the eutectic temperature and composition. 3. Heating and cooling curves, obtained by a refined differential method, leading to new locations for the two peritectic horizontals. In Part I1 of the paper the attempt is made to review all of the published work having a bearing on the constitution of the iron-zinc system, and to correlate the present results, and some recently published data involving the use of X-ray technique, with the earlier work, much of which was done from 25 to 30 years ago.

Jan 1, 1936

By F. J. Alcock

IN the summer of 1934, gold was discovered on Lodge bay, on the north shore of lake Athabaska in northern Saskatchewan, about fifty miles east of the Alberta boundary line. The first claims were taken up by the Consolidated Mining and Smelting Company of Canada, Limited, and there was a 'rush' to locate similar showings. Staking continued through the summer and succeeding winter, and in the spring of 1935 the provincial government established a recording office at a convenient point which is central to the more important holdings and where 'planes can land in any weather. During the past summer, the name of this townsite was changed from Beaverlodge to Goldfields, and a post office was established here. The season was one of great activity; a great deal of assessment and development work was carried out and a large amount of further prospecting done. In addition to the work by private companies, geological investigation was carried out in the region by a Federal Geological Survey party under the charge of the writer and a reconnaissance examination was made of an area of some 7,000 square miles surrounding the region of particular interest. Though this was the first discovery of gold in the region it was not the first occasion that prospecting had been carried out along the north side of lake Athabaska. Over twenty years ago, a number of prospectors were at work in the area and a large number of claims were staked, many of which were never recorded. One man by the name of Piché, in the years 1910, 1912, and 1913, took up a considerable number of claims north of Pine Channel narrows, east of Fond du Lac. His discoveries, which consisted of small showings of sulphides in sedimentary gneiss, proved to be of no economic importance. In 1915, a sudden widespread interest was aroused by the report that a sample of ore collected near Fond du Lac had yielded a very high assay in silver. In March and April of that year, prospectors began to rush into the field by dog teams to take up claims, and, as soon as the Athabaska river was free of ice, others started by boat from Athabaska Landing. Some hundreds of claims were staked and recorded in the Dominion Land Office at Edmonton or at Fort Smith. By July, most of the prospectors had? left the region, having failed to find any silver ore. In 1921, considerable prominence was given to the area a few miles east of Goldfields by reports that very large masses of iron ore were available there. Claims were taken up, but the material is much too low grade to be considered commercial ore.

Jan 1, 1936

PRESIDENT AND DIRECTOR JOHN M. LOVEJOY NEW YORK, N. Y. PAST PRESIDENTS AND DIRECTORS HOWARD N. EAVENSON PITTSBURGH, PA. HENRY A. BUEHLER ROLLA, Mo. VICE-PRESIDENT, TREASURER AND DIRECTOR KARL EILERS NEW YORK, N. Y. VICE-PRESIDENTS AND DIRECTORS LOUIS S. CATES NEW YORK, N. Y. PAUL D. MERICA NEW YORK, N. Y. WILFRED SYKES CHICAGO, ILL. R. C. ALLEN CLEVELAND; OHIO HENRY KRUMB NEW YORK, N. Y.

Jan 1, 1936

By Orson Shepard

THE term "electrocapillary amalgamation" is used in this paper to designate amalgamation processes that depend upon electrocapillary phenomenon; i.e., the action of an electric current upon the surface tension of mercury at the contact with aqueous solutions. Electro-capillary amalgamation is selected as a name for these processes because the electrocapillary phenomenon has been found to be the effective agent in the use of sodium amalgam, as well as in the various processes using an electric current from a source outside of the amalgam. Amalgamation processes that depend upon supplying an electric current to the amalgam from an outside source, such as batteries and generators, have previously been called electrical amalgamation processes. There has been a tremendous amount of experimental work done on amalgamation processes involving the use of an electric current, as shown by the large number of patents issued on these processes: the earliest in 1885 and the latest in 19341. Regardless of all the experimental work, the fundamental principles causing the operation of electrocapillary amalgamation processes have not been described. The explanation usually given is that an electric current keeps the amalgam bright and clean. Patent No. 328532 states: It is well known that when amalgam plates are used for collecting gold and silver from their ores the surfaces of these plates are liable to become tarnished or sickened by certain substances contained in the ores or in the current of water which is employed to carry the ore over the plates, and that in this condition they are unfitted for amalgamating the particles of gold and silver. To prevent this and to keep the surfaces of the amalgamation plates always bright and in a better condition for catching and amalgamating the particles of gold and silver I employ electricity in the following manner:. . . A similar explanation is given 49 years later, in patent No. 1953364: The sodium (Na) ions lose their charge at the cathode becoming sodium atoms, which do not react with the electrolyte, but follow the grounded electrical current through the mercury body producing in their passage sodium amalgam and liberate themselves in the amalgamation compartment when brought in contact with the fed

Jan 1, 1936

By Charles Becker

THE practice of drying phosphate in Florida is as old as the industry, which began a little more than half a century ago. The methods, however, have changed considerably. At first, the natural process of exposure to the sun and air was used, later supplemented by wood fires beneath open-air stationary dry kilns and drying towers of various designs. It was not until the early nineties that rotary driers came into use, and at first they were of very small design and fired with wood. As the industry grew and tonnage increased, so likewise grew the number and size of rotary driers, until today the largest installations are 6 ft. up to 7 ft. 6 in. in diameter, and 55 to 60 ft. long, fired with crude oil. The reasons for drying phosphate rock are: (1) to eliminate freight on water in the shipment and (2) to facilitate the good grinding qualities required by the buyers in their acidulation. Phosphate pebbles vary materially in natural characteristics and each property has a direct bearing on the processing. In making comparisons of cost and operating conditions, the following are usually taken into consideration: 1. The hard dense pebbles, which contain very little interior moisture and 6 to 8 per cent total moisture, usually produced from the low-grade deposits. 2. The lighter, porous pebbles, which contain 4 to 5 per cent interior moisture and a total moisture ranging from 9 to 15 per cent. 3. The product of recovery operations using oily reagents, containing from 15 to 25 per cent moisture. 4. The size of the pebbles. Usually the plus 5-mesh material is considered as "coarse rock"; the minus 5-mesh plus 24-mesh is "fine rock," and the minute particles below 24 mesh are called "concentrate." 5. The amount of moisture allowed in the dried product. The practice is generally to dry down to 1.5 to 2 per cent moisture. There is, however, an actual range in guarantee of from 1 per cent maximum to 3 per cent maximum.

Jan 1, 1936

The Round Table on Qualities of Pig Iron, under the auspices of the Joint Committee on Qualities of Pig Iron, which is made up of members of the American Institute of Mining and Metallurgical Engineers, the American Foundrymen's Association, the American Society for Testing Materials, the Gray Iron Institute, and the Malleable Iron Institute, was held at the Palmer House, Chicago, III., on Oct. 1, 1935. Prcoeedings R. H. SwEEtseR,* New York, N. Y.—Seven years ago last June, in Chicago, we had a round table on qualities of pig iron1, and at that time the foundrymen were out with their battle-axes for the blast-furnace men, and the open-hearth men were doing the same thing. After that meeting there was really a determined effort to find out about the qualities of pig iron, and great progress has been made all along the line. This afternoon we want to have a frank discussion of the qualities of pig iron, whether it is the molten pig iron going into the steel plant, or cold pigs going to the different foundries. We ought to hear something from Dr. J. T. MacKenzie, who is chairman of the Joint Committee, and from Mr. R. E. Kennedy, the Technical Secretary of the American Foundrymen's Association. J. T. MacKEnzie,† Birmingham, A1a.—As a result of that meeting in Chicago, there was considerable agitation in the Foundrymen's Association to develop a set of tests for pig iron. One of the difficulties was that nobody talked the same language on shrinkage, draws, live iron, dead iron, and so forth, which were the main complaints against pig iron. By request of a committee of the Foundrymen's Association, the Bureau of Standards ran a comprehensive set of tests that did develop the principles governing the optical pyrometer as applied to cast iron and pig iron. Then the Bureau went on further with the fluidity test, and developed a method for the absolute changes of volume at the freezing point. There is one serious gap in the yardstick, which has never been developed, and that is the tendency to draws from heavy sections to light. Everyone who has worried about the differences of section, and sponginess in changes of section, realizes that the

Jan 1, 1936

The Middleback Ranges are a series of parallel northsouth ridges on the eastern side of the Eyre Peninsula, South Australia, about 20 miles inland from the Spencer Gulf, as shown in Fig. 1. They extend for some 20 miles across the centre of the County of York. North of them, on the same line of strike, in, the County of Manchester, is a disconnected series of lesser which ends in the Iron Monarch-Iron Knob ridge, the principal iron ore locality. These ridges are referred to in the following pages as an integral part of the Middleback Ranges.The deposits of hematite which outcrop in these ranges (Fig. 1) form the most important group of iron ore bodies in Australia, and are exploited by the Broken Hill Proprietary Company. The largest of them is the Iron Monarch (Fig. 6) .H: The next largest are the Iron Duke, the Iron Prince and Iron Baron. The Iron Knob, Iron Duchess, the North and South Iron Knights, Iron Queen, and the small body south of it, the Kimba Lease, and the deposits in the Cook's and Ash Leases, are all smaller.Numerous small lens-like bodies of hematite occur throughout the ridges, but are not of sufficient size to be of commercial use. At present only the Iron Monarch and the Iron Prince bodies are being worked. The Iron Knob was quarried previously, but its remaining supply is held in reserve.*Published by permission of the Council for Scientific and Industrial Research.

Jan 1, 1936

By Met B. E

The increasing pace of modern mining makes constantly greater demands upon the several contributing departments of rock breaking and transport, and rock-drilling, as the spearhead of attack, has received a great deal of attention with respect to both machines and steels. By a series of mechanical improvements, combined with the application of selected heat-treated alloy steels, the rock-drill has now been developed into a machine capable of rapid drilling and long service under severe working conditions. As a factoryproduct made under strict metallurgical control it is as foolproof as, say, the modern automobile, and, like its prototype, it can be kept in efficient operation by a minor amount of attention during use and by periodical adjustments and replacements.The same cannot be said, unfortunately, of the drills with which the machine is supplied; in conventional mine-shop practice these are made of the best tool steel shaped and heat-treated under the poorest of metallurgical conditions.The crudities of steel-shop practice have, in fact, always prevented the full exploitation of the steels available at any time, and even at the present day the general standard of treatment offers a contrast with the quality of the steels which moves the metallurgist to amusement, despondency or outrage, according to his temperament. Nevertheless, the tendency persists to meet the increasing demands of the rock-drill primarily by the use of still better steels, and secondarily by improvement, of the steel-shop practice. Athird type of development is the introduction of factorymade tools in the form of detachable bits and rods. It is proposed in this paper to deal with these three aspects of the recent developments in rock-drilling.*Re-written from a lecturette given during the First Ordinary Meeting, 1936.

Jan 1, 1936

By Hertha Freche

THE diffusion of magnesium and silicon from the core into the high-purity coating of Alclad sheet is important commercially, and led to the use of a duplex product for the study of diffusion by means of spectro-graphic analysis of successive layers. It has been found that in the duplex materials the diffusion of magne-sium from an undersaturated aluminum-magnesium alloy into its high-purity aluminum coating is approximately of the same order of magnitude as the diffusion of silicon from a saturated aluminum-silicon alloy into its high-purity aluminum coating. However, if magnesium and silicon are both present in the alloy in the ratio of Mg2Si they appear to diffuse in the approximate ratio of this compound. Finally, if the alloy contains silicon in excess of the amount required by magnesium silicide, the amount of diffused silicon in the high-purity aluminum coating will also be in excess. The interdiffusion of metals in the solid state is of both scientific and technical interest, because it is helpful in the study of the alloy structure and in the solution of problems pertaining to the strength and surface condition of the fabricated product. W. C. Roberts-Austen1 carried out the first quantitative determination of the coefficient of diffusion of gold into lead. This classical experiment was followed by a series of investigations on the diffusion of metals and nonmetals in iron and steel and in nonferrous metals and alloys. Recently the diffusion of copper in coated strong aluminum alloys was investigated by A. Burkhardt2. This appeared to be the first published investigation on the diffusion of metals into aluminum.

Jan 1, 1936

By Gilbert Thiessen

THE use of a pneumatic process for removing fine material (usually less than 48-mesh) is increasing in, the preparation of stoker-size coal. The fine material, produced as a byproduct, is known as dedusting-plant dust. Since fusain is the most friable ingredient in bituminous coal (it may readily be rubbed to an impalpable powder with the fingers), it tends to accumulate in this byproduct. While studying the properties of cokes produced by blending Illinois coals with other materials, considerable quantities of fusain were required. Dedusting-plant dust suggested itself as a-convenient supply. It became necessary, therefore, to determine how much fusain was contained in a measured sample of dust, how the fusain was distributed with respect to size and specific gravity in the sample, and whether or not it would be feasible or desirable further to concentrate or to recover the fusain from, the dust before using it in the blends to be coked. The results obtained indicate the possibilities of production of a high-fusain material.

Jan 1, 1936