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By C. S. Roberts

Microstructural studies of a Mg-10.3 pct Al alloy showed that discontinuous precipitation during aging multiplies the grain boundary area available for easy deformation in elevated temperature creep. An increase of strain rate for a 6.2 pct Al alloy at 400°F, where precipitation and creep are concurrent, caused an increase in the volume percentage discontinuously precipitated at the completion of the process. The relatively poor elevated temperature creep resistance of heat treated alloys of the Mg-AI-Zn type was explained in these structural terms. C resistance of the heat treatable Mg-A1 based alloys is poor compared to that of Mg-Ce based alloys. While the latter show a continuous precipitate, Mg-A1 alloys prefer a discontinuous precipitate at grain boundaries. '.:' It has been concluded that the excellent creep resistance of Mg-Ce alloys was primarily due to the continuous precipitation which especially localized at the grain boundaries.' The purpose of the present investigation was to obtain a parallel correlation, if such exists, between the poor creep resistance and the state of precipitation in Mg-A1 alloys. Discontinuous precipitation produces about three times as many true grain boundaries as originally existed. This microstructure would be expected to have a marked influence in creep, where quantity of grain boundary area is important. Experimental Procedure The two experimental alloys contained 6.2 and 10.3 pct Al. They were made from electrolytic magnesium by alloying under flux and casting in 3 in. diam permanent molds. The ingots were extruded into 1 1/4 x 1/8 in. flat stock under the following conditions: billet preheat 700°F (2 hr), container and die temperature 700°F, speed 3 fpm, and area reduction ratio 45:1. The creep specimens were machined from blanks which had been solution heat treated 24 hr at 770°F and aged 16 hr at 400°F. Attempts were made to control the grain size as closely as possible for extruded stock. The grain size after solution heat treatment was about two thousandths of an inch for the 6.2 and five thousandths for the 10.3 pct Al alloy.

Jan 1, 1957

By D. K. Crampton

The object of this work was to obtain and correlate information on effect of internal stress in variously drawn tubes on several properties. Also, a simple approximate method of comparing types of stress distribution in such variously drawn tubes was sought. There is also included some work on comparison of single and polycrystalline materials and effect of different types of operation and preferred orientation. Preparation of Material A series of tubes was drawn to study the effect of the type and degree of final reduction on various physical properties and the approximate distribution of stress intensity across the tube wall. The material used all came from a single heat of 70-30 brass melted in a regular production Ajax-Wyatt induction furnace. The analysis of the metal as cast was: copper, 70.36 per cent; lead, 0.04; iron, 0.02; zinc, balance. The material was cast in "shells" with 4 in. outside diameter and in. wall thickness. It was drawn part way down according to the usual standard mill schedule and then by suitable individual schedules to finish by a variety of types and degrees of drawing to the same final cases in every instance; namely, 0.750 in. outside diameter by 0.080 in. wall thickness. The exact final draws, together with the percentage area reductions, diameter reductions and gage reductions are given in Table 1. In fabricating these tubes, rather unusual precautions were observed to insure the elimination of ail variables not under immediate study. All intermediate anneals were carried out at about 1200" F. down to the so-called "cut-in size"; namely, 17/16 by 3/16 in. From this point on, all anneals were made at from 1050' to 1100" F. The greatest care was used all through to have the tubes as free from minor surface defects as possible. When such defects were visible on intermediate sizes they were carefully filed out. On the final draw to 3/4-in diameter the die was aligned with the greatest possible precision in order to insure as straight a tube as possible

Jan 1, 1933

By Herbert Clark Hoover, Lou Henry Hoover

MOST illustrious Princes, often have I considered the metallic arts as a whole, as Moderatus Columella2 considered the agricultural arts, just as if I had been considering the whole of the human body ; and when I had perceived the various parts of the subject, like so many members of the body, I became afraid that I might die before I should understand its full extent, much less before I could immortalise it in writing. This book itself indicates the length and breadth of the subject, and the number and importance of the sciences of which at least some little knowledge is necessary to miners. Indeed, the subject of mining is a very extensive one, and one very difficult to explain ; no part of it is fully dealt with by the Greek and Latin authors whose works survive ; and since the art is one of the most ancient, the most necessary and the most profitable to mankind, I considered that I ought not to neglect it. Without doubt, none of the arts is older than agriculture, but that of the metals is not , less ancient ; in fact they are at least equal and coeval, for no mortal man ever tilled a field without implements. In truth, in all the works of agricul- ture, as in the other arts, implements are used which are made from metals, or which could not be made without the use of metals ; for this reason the metals are of the greatest necessity to man. When an art is so poor that it lacks metals, it is not of much importance, for nothing is made without tools. Besides, of all ways whereby great wealth is acquired by good and honest means, none is more advantageous than mining ; for although from fields which are well tilled (not to mention other things) we derive rich yields, yet we obtain richer products from mines ; in fact, one mine is often much more beneficial to us than many fields. For this reason we learn from the history of nearly all ages that very many men have been made rich by the

Jan 1, 1950

By Gerhard Derge

EXTRUSION processes are used in the commercial production of a wide variety of products, as indicated by the review presented a few years ago by D. K. Crampton.1 Most writers have confined themselves to a general description of the equipment and products and the engineer-ing aspects of the process. The few studies that have dealt with the metallurgical side of extrusion have been concerned primarily with an examination of the mode of flow of the metal during extrusion. This has been accomplished by the use of composite billets, by scribing grids on symmetrical sections of billets and observing the change of dimensions in the gridwork, or by examining microstructures in extruded sections.2-8 Another limitation of these original studies is that they were confined to the extrusion of very simple shapes, usually rods having a diameter of about one-fourth that of the billet. Tin is particularly well suited to the extrusion of collapsible tubes and similar shapes in which the extruded section is very small in comparison to the diameter of the billet or slug. In modern production, impact extrusion methods are generally employed, therefore the thickness of the slug is small compared to its diameter. Under these conditions the process differs considerably from the processes that have been most fully described in the literature, and it is known that the quality of the product is very sensitive to slight variations in any one of the many variable factors involved, such as composition and structure of the alloy, rate of extrusion, temperature, shape of punch and die. An exhaustive examination of all of the above-mentioned problems promises to produce so many data that it seems advisable to initiate the reports at this time, even though all of the factors outlined have not been examined fully, and to confine this paper to a description of the apparatus and method. Only tin and its alloys with small amounts of copper have been considered. These are the alloys most commonly used in this country for the production of the type of articles already described.

Jan 1, 1939

By Tracy C. Jarrett

In making gold alloys possessing certain physical properties, such i~nportant factors as corrosion resistance, color, hardness and melting points must be considered. All of these requirements depend directly upon the composition. It is possible to obtain the same colored gold alloy by using different compositions, but in doing so one may bring in some undesirable property. Other investigations have been carried on in this field by F. E. Carter,' E. M. Wise12 and L. Sterner-Rainer2 To make a complete study of the effect of composition upon these properties, a systematic investigation was carried on involving a range of copper content from 85 to 65 per cent. Elements such as zinc, silver and nickel were used to replace in part the copper content. The gold content in all the alloys remained constant. Only 10-karat gold alloys of those containing 41.6 per cent gold will be considered. All of the alloys were made in an induction furnace. Each alloy was cast in a 3 by 1/4 by 3/4-in. ingot. The method of obtaining the melting points and making color determinations was described in a previots paper.4 The Rockwell B scale with the 1/16-in. ball and 100-kg. weight was used for all hardness determinations. The submersion of test pieces in concentrated nitric acid is one of the standard corrosion tests used in the optical trade. A test piece in the 50 per cent cold-worked condition, % by 2 by 0.045 in., is blanked from a skip using a die, and the weight loss per square inch of surface is taken as a means of comparison. The time for this test is 2 1/2 hr. of actual submersion of the test picce in the acid. This standard test was applied to all of the 10-karat gold alloys discussed in this paper. The tensile tests were made upon strips of the dimensions shown in Fig. 1. The test pieces after blanking were annealed at 1300" F. for 20 min. and cooled in air. Thc "drop of the beam" method was used in determining the yield point, as there was a very marked "drop" when the yield point was reached.

Jan 1, 1940

By Tracy C. Jarrett

In making gold alloys possessing certain physical properties, such i~nportant factors as corrosion resistance, color, hardness and melting points must be considered. All of these requirements depend directly upon the composition. It is possible to obtain the same colored gold alloy by using different compositions, but in doing so one may bring in some undesirable property. Other investigations have been carried on in this field by F. E. Carter,' E. M. Wise12 and L. Sterner-Rainer2 To make a complete study of the effect of composition upon these properties, a systematic investigation was carried on involving a range of copper content from 85 to 65 per cent. Elements such as zinc, silver and nickel were used to replace in part the copper content. The gold content in all the alloys remained constant. Only 10-karat gold alloys of those containing 41.6 per cent gold will be considered. All of the alloys were made in an induction furnace. Each alloy was cast in a 3 by 1/4 by 3/4-in. ingot. The method of obtaining the melting points and making color determinations was described in a previots paper.4 The Rockwell B scale with the 1/16-in. ball and 100-kg. weight was used for all hardness determinations. The submersion of test pieces in concentrated nitric acid is one of the standard corrosion tests used in the optical trade. A test piece in the 50 per cent cold-worked condition, % by 2 by 0.045 in., is blanked from a skip using a die, and the weight loss per square inch of surface is taken as a means of comparison. The time for this test is 2 1/2 hr. of actual submersion of the test picce in the acid. This standard test was applied to all of the 10-karat gold alloys discussed in this paper. The tensile tests were made upon strips of the dimensions shown in Fig. 1. The test pieces after blanking were annealed at 1300" F. for 20 min. and cooled in air. Thc "drop of the beam" method was used in determining the yield point, as there was a very marked "drop" when the yield point was reached.

Jan 1, 1940

By Tracy Jarrett

IN making gold alloys possessing certain physical properties, such important factors as corrosion resistance, color, hardness and melting points must be considered. All of these requirements depend directly upon the composition. It is possible to obtain the same colored gold alloy by using different compositions, but in doing so one may bring in some undesirable property. Other investigations have been carried on in this field by F. E. Carter,1 E. M. Wise,2 and L. Sterner-Rainer.3 To make a complete study of the effect of composition upon these properties, a systematic investigation was carried on involving a range of copper content from 85 to 65 per cent. Elements such as zinc, silver and nickel were used to replace in part the copper content. The gold content in all the alloys remained constant. Only 10-karat gold alloys of those containing 41.6 per cent gold will be considered. All of the alloys were made in an induction furnace. Each alloy was cast in a 3 by ¼ by ¾ -in. ingot. The method of obtaining the melting points and making color determinations was described in a previous paper.4 The Rockwell B scale with the ball and 100-kg. weight was used for all hardness determinations. The submersion of test pieces in concentrated nitric acid is one of the standard corrosion tests used in the optical trade. A test piece in the 50 per cent cold-worked condition, ½ by 2 by 0.043 in., is blanked from a strip using a. die, and the weight, loss per square inch of surface is taken as a means of comparison. The time for this test is 2 ½ hr. of actual sub-mersion of the test piece in the acid. This standard test was applied to all of the 10-karat gold alloys discussed in this paper. The tensile tests were made upon strips of the dimensions shown in Fig. 1. The test pieces after blanking were annealed at 1300° F. for 20 min. and cooled in air. The "drop of the beam" method was used in determining the yield point, as there was a very marked "drop" when the yield point was reached.

Jan 1, 1939

By G. W. P. Rengstorff, H. B. Goodwin

A method is described for purifying iron in batches of 150 Ib or more. Oxygen, carbon, nitrogen, and sulphur are removed from flakes of electrolytic iron by treatment in wet and then dry hydrogen. A special consumable-electrode arc furnace is used to remove hydrogen and to melt the flakes into ingots. A LTHOUGH iron and steel have been made and used for hundreds of years, there are still wide gaps in the knowledge of these metals. One reason for this is that the true properties of the base metal, iron, are not well known, simply because really pure iron has never been readily available for research purposes. Commercial iron, and even the "pure" irons which are readily available, are really complex alloys of iron with oxygen, nitrogen, hydrogen, carbon, sulphur, silicon, and other elements. With such materials, it has not been possible to prepare steels and other iron-base alloys in which all elements are present in exactly controlled amounts. It is an almost impossible task to determine the separate effects of each element or the intereffects of several elements unless alloys can be prepared containing only the desired elements. The ability to make controlled alloys of low impurity content is of far more than academic interest. It will assist in the study of such practical problems as the brittle failure of ship hulls or high pressure gas pipelines, determination of the factors which affect the deep-drawing properties of steels, the improvement of magnetic and electrical properties, the phenomenon of aging, and many others. In 1949, the American Iron and Steel Institute asked Battelle Memorial Institute to prepare high purity iron on a larger scale than had been attempted up to that time. The work was directed toward the preparation of iron as low as possible in carbon, oxygen, nitrogen, hydrogen, and sulphur because these are the contaminating elements of major interest in many research investigations on iron-base alloys. The initial goal was to prepare iron with not more than a few thousandths of one percent of each of these impurities. The purpose was to set up a "bank" of high purity iron on which researchers could draw when a supply was needed and which could be replenished from time to time as the stock became depleted. Of several possible purification methods, heating in hydrogen was selected as the most promising for the removal of both carbon and oxygen from solid iron. Metallic impurities are not removed by hydrogen. Electrolytic iron was chosen as a starting material because it is the most readily available form of iron low in metallic impurities. Decarburization and desulphurization were obtained by annealing in wet hydrogen at relatively low temperatures. The optimum temperature, as found by previous investigators,' is about 1400°F. This treatment also removes nitrogen. Deoxidation is favored by dry hydrogen and higher temperature. There is evidence from previous work that an anneal at 2200°F in dry hydrogen will deoxidize the iron, reduce the nitrogen content, and reduce the sulphur content. These facts suggested the use of a two-stage process: treatment in wet hydrogen followed by treatment in dry hydrogen. To carry out the purification process in a reasonable time, it was necessary that the iron be in thin pieces. Flakes of electrolytic iron were used. Because most research requires that the iron be in massive form, it was nccessary to melt the purified iron to consolidate it into large pieces. For this work, it was decided to prepare ingots weighing at least 15 lb by using a cold hearth arc-melting process in which the iron was melted in an inert atmosphere of argon or helium. This method of melting was selected because the water-cooled copper crucible is not wet by the iron and does not contaminate it as a refractory crucible would. Because the crucible is also the ingot mold, contamination from mold materials was also eliminated. Contamination from electrodes was avoided by making them from purified electrolytic iron. The melting procedure finally developed was an adaptation of the Kellogg electric ingot process.' Two batches of purified iron weighing about 100 Ib each in ingot form were prepared with analyses as shown in Table I. The remainder of this paper describes the procedures in more detail. In general, the process con-

Jan 1, 1956

By Dorsey Hager

The possibility of oil and gas production in Alabama his been little considered as yet. Gas and some oil have been found in northwestern Alabama, near Birmingham, in the Pennsylvanian beds, but the oil and gas possibilities in the Cretaceous beds are not generally appreciated. The recent activity of oil companies in that State has attracted much attention, and in this paper the main structural and the general strati-graphic features are described. Four favorable areas are outlined. These contain folds of major interest. There are other favorable areas which have not been mapped-l Commercial pools discovered in this area would have the advantage of being near tidewater. Mobile, Ala., on the Gulf of Mexico, would be the logical site for refineries and shipping facilities. A pipe line could readily be laid to that city from the Hatchitigbee and the Jackson areas. The logical outlet for the Geneva and the Gordon areas would be Panama City, Ha., on the Gulf of Mexico. Topography The whole of the area under consideration lies in the Gulf coastal plain and slopes gently to the southwest and west. The elevations vary from 200 to 400 ft. (60 to 121 m.) above sea level. The streams have sunk their channels into this gently sloping plain, the main drainage flowing south or southwest into the Gulf of Mexico. Between the

Jan 1, 1918

By AIME AIME

JOHN HUNTER NEAD, chief metallurgist of the Inland Steel Co., Chairman of the Iron and Steel Division for 1939, a native of Missouri and graduate of the University of Michigan, first taught chemistry after graduating from college and then decided to follow the field of his college specialization and be a metallurgist. In succession he was associated with the H. H. Franklin Co., Syracuse, N. Y., the Watertown Arsenal, the Racine Steel Castings Co., and the Minneapolis Steel and Machinery Co. During the World War he held a commission as Captain in the Ordnance Department and served both overseas and on the technical staff in Washington. Returning to civilian life, Hunter Nead was research metallurgist and then chief metallurgist of the American Rolling Mill Co. from 1919 until 1931, when he went to his present position with Inland.

Jan 1, 1939

By A. B. Kinzel

THE year 1936 has been an eventful one in the iron and steel industry. Renewed industrial activity has brought with it many new problems. These problems have generally involved the question of increasing capacity without sacrifice of economies and quality developed in the less active previous years. The nature of the iron ore used and the effect of its porosity and other physical characteristics on the capacity of the blast furnace has been reviewed by the U. S. Bureau of Mines. The whole question of handling raw materials and methods of charging furnaces has been intensively studied, with the result that capacity has been in- creased without affecting the quality of

Jan 1, 1937

Book Review MANAGEMENT AND MEN. By Meyer Bloomfield, Boston. The Century Co., New York, 1919, pp. 584, H.X. 5 1/2. $3.50. This hook is an exposition of English efforts to solve the problem of labor unrest in England. The first six chapters are reprinted from articles published in the Satur-day Evening Post, for whom the author went to England to study the problem at first hand. These articles deal with housing, increased production, eliminating the internal friction in the industrial machine and a chapter each devoted to the view-point of employer and employee. These chapters are written in the easily readable magazine style and give a complete general survey of the particular solution being tried. Perhaps their greatest., certainly not their least, worth lies in the fact that they form a vehicle for unusually voluminous appendices containing in full the famous Whitley Reports which are the basis of the new movement, together with various reports, which, except for this publication, would be largely inaccessible to those inter-ested in this country. The Whitley scheme considers each industry a unit and proposes to establish therein a Joint Standing Industrial Council composed of representatives of employers and employees to consider appropriate matters affecting the industry at large. There is to be a District Council for each industry which will, as its name implies, deal with the clatters pertaining to that interest in. the particular district. The third and last body in this scheme of Industrial Parliament is the Works Committee, which is com-posed of representatives of the management and of the workers employed in particu-lar plants or mines to act in close cooperation With the district quid national machinery. The Whitley or similar schemes have been tried in many communities in England and the book contains interesting comments on the result obtained, it being notable that most of the objections conic from plants which have not tried the scheme. Meyer Bloomfield, the author; is the specialist in industrial personnel problems who organized the industrial service activities of the United States Shipping Board, Emergency Fleet Corporation. P. E. B.

Jan 10, 1919

By Benjamin C. Craft

As predicted, during 1937 South Louisiana witnessed one of the most active drilling campaigns in the history of the area, resulting in the discovery .of 14 new fields. The economic importance of 10,000-ft. production was far-reaching and the objective depths placed on some wildcats was 12,000 feet. Most of the important discoveries and deep tests were in the delta area between the Atchafalaya and Mississippi Rivers, where the upper Miocene sands were found productive between 10,000 and 11,000 ft. The casing program on these wells usually called for a protection string of 95/8-in. casing at approximately 9500 ft. Drilling barges with the heaviest equipment were used where water transportation was available. The oil production for South Louisiana during 1937 was 62,147,690 bbl., as compared with 51,968,727 bbl. during 1936, an increase of 19.5 per cent. There were 281 oil and gas wells and 172 dry holes completed during 1937 as compared with 262 oil and gas wells and 135 dry holes during the previous period. New Fields Gibson.—The first discovery for the year was in the Gibson area, where Shell Petroleum Corporation's Realty Operators No. 1, sec. 18, 17 S., 15 E., Terrebonne Parish, was completed flowing 780 bbl. of 38° A.P.I. oil daily through a 14/64-in. choke with a tubing pressure of 1700 lb. Production is from upper Miocene sand found from 9461 to 9483 feet. Abbevil1e.—The discovery well for the Abbeville field was Continental Oil Company's Hebert No. 1, sec. 20, 12 S., 3 E., Vermilion Parish, completed flowing 50 bbl. of distillate and 2 million cubic feet of gas through a 3/16-in. choke with a tubing pressure of 2550 lb. The well was plugged back from 12,216 ft. in the Chickisawhay, and is producing through perforations from upper Miocene sand found from 7668 to 7682 ft. Later in the year, the same operators completed Brookshire No. 1, sec. 66, 12 S., 3 E., flowing 366 bbl. of 42° A.P.I. oil per day through a 3/16-in. choke with a tubing pressure of 1800 lb. This well was com-

Jan 1, 1938

Following the suggestion of Engineering Council and at the direction of, the President, representatives from each of the Federal Government bureaus interested in map-making were called into a conference for the purpose of coordinating all of the Government's map-making activities. This conference has now reported back to the President the results of its findings, which indicate that Engineering Council's recommendation in this matter was well founded. While the conference report states that its members were of the opinion that little duplication of effort existed, it recommends the formation of a permanent Board of Surveys and Maps. An extended review of the map-making activities, which is given as an appendix to the report, indicates that this recommendation is a logical step. The conference recommendations concerning this Board of Surveys and Maps are as follows: (1) the Board is to he com-posed of representatives of mapping bureaus to be assisted by outside engineering organizations, which have been named above; (2) the estab-lishment of an information office in one of the Government bureaus, preferably the Geological Survey, which is to be under the supervision of the Board and is to be a mapping information clearing house for the Government and outside engineering organizations; (3) copyright laws are to be so changed that copies of all. maps made in the United States and with Governmental authority, will go to the central information office; (4) the Government departments are to receive orders to cooperate, with the Board; (5) future topographic maps of all kinds are to conform with specifications for the standard topographic map; (6) the U. S. Coast and Geodetic Survey to have supervision of final adjustment of all important control data under specifications approved by Board of Surveys and Maps; (7) surveys in the form of maps and publications are to be issued as soon as possible after field work has been completed; (8) program of the Interdepartmental Committee on Aerial Surveying was approved. Outside technical and scientific organizations that are called in for consultation are to operate in an advisory capacity only, responsibility for action on Governmental work is. to rest solely with the Governmental agencies.

Jan 12, 1919

By T. B. Massalski, Horace Pops

Martensitic transformations were observed by optical metallography and electrical-resistivity measurements during cooling at cryogenic temperatures of the bcc pr-phase Au-Zn alloys. The com-position dependence of the MS, MF, AS , and AF temperatures have been determined. It is concluded that the martensitic platelets which grow mainly in the lengthwise direction and which are associated with a very small temperature hysteresis are "thermoelastic" martensite. In some cases the observed structure seems to have no definite crys-tallographic habit or consists of a mixture of- plates and broad transformed areas. THE majority of the bcc /3-phase alloys in systems of copper, silver, and gold with zinc and cadmium are unstable at low temperatures and undergo a transformation upon further cooling into another structure. A large number of such transformations are martensitic. The composition dependence of the Ms temperatures has been determined and reported for CU-~n,' Ag-Cd,' and AU-C~~ alloys. The 50 at. pct ordered Au-Zn p' alloy has been reported by Jan and pearson4 to transform martensitically at 58°K in connection with their study of the de Haas-van Alphen effect The p' phase in the Au-Zn system has the ordered CsC1-type structure. The phase field is shown in Fig. 1: it has the typical V shape which is characteristic of all copper-, silver-, and gold-based binary /3-phase alloys. There appears to be no a priori reason why the transformation should be limited to the equiatomic composition and the availability of a cryogenic stage for optical metallography5 has permitted studies down to the liquid-helium temperature of a series of alloys in this system. EXPERIMENTAL PROCEDURE Predetermined weights of 99.999 pct pure gold and zinc were melted and cast under a partial atmosphere of helium in sealed quartz capsules. Thorough mixing of the molten metals was achieved by vigorous shaking, followed by a rapid quench into a brine solution. All ingots were homogenized at 640°C for 4 days. The loss in weight was usually less than 0.04 wt pct and was assumed to be due to

Jan 1, 1965

By John B. Myers

VERMICULITE is a name used to describe micaceous material that exfoliates when heated. It is hydrated magnesium-aluminum-iron silicate. The chemical composition, color, physical appearance, and degree of exfoliation vary. COMPOSITION, PROPERTIES, AND ORIGIN Vermiculite has the characteristic micaceous structure of basal cleavage and readily splits into thin laminae, which are soft, pliable, and inelastic. The monoclinic crystal faces are often marked by triangular lines at 60° and 120°. Hardness is 1.5; specific gravity, 2.2-2.7; luster pearly to greasy; colors, amber, bronze, reddish brown, dark green, and black. Feel is soapy, particularly when wet. When heated it exfoliates by expanding at right angles to the cleavage into long wormlike pieces (the name vermiculite is from the Latin veamiculari, to breed worms). This important characteristic of expansion is believed to be a mechanical separation of the layers when the contained water is converted into steam. Warping of the unit layers may also contribute to the expansion. The increase in bulk volume of commercially prepared material is 8 to 12 times but individual flakes may increase in size more than this. Pure vermiculite is a distinct mineral and has the structural formula (OH), (Mg,Fe)3 (Si,Al,Fe)4 010.4H20. It rarely occurs in this pure form, but generally as a mixed mineral of varying structure. One explanation is that the mixed material is composed of unit layers of inter-stratified pure vermiculite and biotite. The essential difference between the two is that unit cell structure of vermiculite contains a layer of water molecules whereas the biotite cell contains potassium instead of the water. The water content of the mixed vermiculite is less than that of pure vermiculite but more than that of biotite. Pure biotite does not expand when heated. If the proportion of biotite layers in a vermiculite is too high it will adversely affect the degree of exfoliation. Within a given deposit, the great mass of material may approach a definite com-position with local areas of greater biotite content. It is not uncommon to find also small pockets of pure biotite but these are generally segre-

Jan 1, 1949

By W. S. CAYPLESS, H. O. Hofman, E. E. HARRINGTON

I. INTRODUCTION. LIME-ROASTING is a term proposed by Ingalls 1 for the operation of forcing air under pressure through a mixture of galena and lime at the kindling-temperature with the object of oxidizing lead and sulphur and of fritting or fusing the charge. If, finely-divided galena were treated in this manner without the addition of lime, the heat set free by the oxidation of part of the lead and the sulphur would be sufficiently great to fuse undecomposed sulphide, and thus stop desulphurization. Besides the chemical action that the addition of lime, limestone or gypsum to the charge may have, the admixture has the physical effect that it keeps the particles of galena separated from one another and accessible to the oxidizing effect of the air. At present, three methods of lime-roasting are carried out on a working-scale, the Huntington-Heberlein, the Carmichael-Bradford and the Savelsberg2 processes. In the last, which interests us here, an 8-ton charge is made up of galena, limestone and perhaps some siliceous or ferruginous flux; the whole is crushed to pass a screen with 3-mm. holes and moistened with 5 per cent of water. It is fed gradually into a bowl-shaped converter, 6.56 ft. in diameter, supported by trunnions attached to a truck. On the .bottom the converter has a grate with blast-inlet beneath. In starting, the truck with the converter

Jan 1, 1907

By Winston W. Spencer

ALTHOUGH by far the largest A consumer of platinum metals in the world, the United States until recently has been in- significant as a producer. Writing in the "Minerals Yearbook" for 1939, H. W. Davis states that 1938 probably marked the beginning of an- other period of transition in the world production of the platinum metals. In that year, he says, their production in the United States jumped to 49,380 oz., or fourth in the rank of world output. In the ten-year period 1925 to 1934 United States output ,averaged only 8300 oz. Practically all of this sudden in- crease in production is attributable to the introduction of mechanized equipment at the placer deposits in the Goodnews Bay district of Alaska. This district adjoins the Bering Sea and Kuskokwim Bay (accented on the first syllable), and is approximately 120 miles south of the mouth of the Kuskokwim River. The nearest village and post office is Platinum, which lies about eleven miles north- east of the Goodnews Bay Mining Company's camp. A good gravel road connects the mine camp and the village.

Jan 1, 1940

WELL known member of the Institute, Henry Krumb, survived the Japanese earthquake and has written a most interesting description of his personal experience to a friend in New York, an extended excerpt from which we publish, by permission, below. Not having been written for publication it has increased value as a human document in its vivid description of personal impressions and sensations in the midst of such a catastrophe. The earthquake was the most terrible experience I have ever passed through. We arrived at Miyanoshita, Friday, Aug. 31, about 6 p.m., having left Yokohama about 2:30 that afternoon by automobile. It was a most beautiful ride, although rather warm, but not unusually so, as it has been uncomfortably hot ever since we arrived in Japan. The first part of this automobile trip was along the old highway from Kyoto to Tokyo, which is lined with fine old pine trees. There are 52 villages along this highway and we saw real Japanese country life: naked children, both boys and girls, and men wearing nothing but gee-strings. The country on either side was intensively cultivated, the green rice fields and lotus ponds making a most beautiful sight. The occasional hills were all re-forested with young pines. In places the road runs close to the ocean beaches. The last part of the trip was up a steep mountain road, cut out of the side of the mountain. On one side of the road, in the gulch below, was a roaring river. The road crosses this river several times. Miyanoshita is beautifully located on the side of a mountain about 400 ft. above this river at an altitude of 1400 ft. The grounds of the hotel are laid out in Japanese style, small lakes with fish, waterfalls and dwarf trees making a very pretty sight. On the morning of Sept. 1, after walking around the garden and the hotel, we went to our room and I started to write up a few notes. Mrs. Krumb was reading a guide book. A few minutes before noon she came over to the table where I was writing and said that it was about lunch time. Just at that moment hell broke loose. It was the first earthquake I have ever experienced and I did not immediately realize what was happening. The building was shaking as a mine office might shake when heavy blasting was going on near by. Mrs. Krumb, having experienced many earthquakes, stepped to the open door between our room and the bathroom and called to me to get out from under the chande-lier. The plaster was commencing to fall and a large wardrobe fell over. I then knew what was happening and ran to the win dow. Before I reached it a large chunk of plaster from the ceiling hit me on the head and cut my forehead and nose. Mrs. Krumb ran for the other window just as the marble mantelpiece and the dresser fell. Without any hesitation, she jumped out of the win-dow and I followed suit out of the other. Luckily neither of us sprained an ankle-we had jumped 8 ft. We started to runaway from the building but had not gone more than 25 ft. when a second shock or rather a continuation of the first became so violent and the ground under our feet was trembling so that it was almost impossible to stand up without holding on to a tree. The ground seemed to have become liquid and rocked violently, it seemed to me in a vertical direction. In some later shocks the movement was more horizontal. About this time Mrs. Krumb saw the blood on my face and commenced to break down, but only for a moment: As soon as she saw it was not serious she was all right and during the following days stood the experiences and hardships as well as the best of them:

Jan 11, 1923

By Leroy Gardner

EVERY reader of this paper is well aware of the fact that the prolonged inhalation of large amounts of free silica dust results in fibrosis of the lungs, and that other inorganic dusts, except those of asbestos and the mineral poisons, are thought to be relatively harmless. But probably few have had opportunity to visualize the effects of silica, asbestos and other minerals upon living tissues. The ideal demonstration would be based upon sections of lungs from human beings that had inhaled com-parable concentrations of different dusts for a unit period of time. Such material is generally difficult to obtain and in some instances is of ques-tionable value because the subject has been exposed to more than one kind of dust. A demonstration could be prepared from the lungs of animals. However, so many months or even years are required to com-plete the exposure to each kind of dust that enough material has not been accumulated. For a general survey of the action of different types of dust, I am therefore compelled to use the tissues of animals that have been injected with suspensions of dust particles. The injection method offers certain advantages. The quantity, the particle size and the state of dispersion can be controlled with sufficient accuracy so that the tissue responses to different minerals can be accu-rately compared. The method insures contact between the tissues and the mineral particles; protective mechanisms, which may prevent the inhalation of certain types of foreign body, never come into play. If the pathway of injection be one that minimizes nonspecific injury, the tissue responses may simulate those produced by inhalation but they develop somewhat more rapidly. It should always be remembered that injection methods merely demonstrate the capacity of various kinds of minerals to provoke reaction in the tissues; whether the same substances are inhaled from atmospheric suspension and accumulate in the lungs in dangerous quantities can be demonstrated only by inhalation.

Jan 1, 1938