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By T. V. Philip, Paul A. Beck

IN a previous note1 it was pointed out that the available information suggests a distinct correlation between the occurrence of the CsCl-type ordered structures formed in equi-atomic binary alloys of transition elements and the location of the components in the periodic table. A definite increase in the bond strength between unlike atoms, as compared with that between like atoms, is indicated when, in binary alloys of iron group elements, the other component is changed from chromium to vanadium or tantalum, to titanium. Laves and Wallbaum,2 eported a CsCl-type ordered structure for the stable intermediate phase at the equi-atomic composition in the Ti-Fe system (and also in the Ti-Ru and Ti-Os systems). On the other hand, Tagaya, Nenno, and Nishiyama8 found no ordering of this kind in the body-centered-cubic solid solutions in the Cr-Fe system. It was concluded' that the occurrence of a CsC1-type ordered phase of intermediate stability may be expected in the V-Fe system. Preliminary results were described: suggesting that at least some degree of order does exist in the equi-atomic alloy VFe, annealed at 1200° C and quenched in cold water. Using CrK radiation, at least one weak superlattice line was found in the X-ray diffraction pattern which could be indexed as (100). and which disappeared, as expected, when FeK radiation was used. It was found more recently that the impurity phase (presumably VN), previously giving rise to additional X-ray diffraction lines and thus preventing definite indentification of the (111) superlattice line,' can be eliminated by preparing the alloy by arc melting in a helium atmosphere. The alloy specimen melted in this manner had clean surfaces and showed very littte, if any, nitride phase in the microstructure after annealing in vacuum at 1250°C and quenching. The relative intensity of the (100). superlattice line with CrK radiation was greatly increased and, in addition, a fairly strong (Ill) , superlattice line and even a detectable (210) , super- lattice line was obtained, when the powder produced by filing from the 1250°C annealed and quenched specimen was reannealed in vacuum at 625°C for 1 hr. By using a cellulose acetate film as a filter in front of the photographic film in order to absorb the soft radiation resulting from air fluorescence, the background intensity could be reduced considerably in relation to the intensity of the diffraction lines. All three superlattice lines, (100),, (111)., and (210)a, disappeared, as expected, when a radiation other than CrK, was used.1 For the powder reannealed at 625ºC, the strongest lines of the s pattern also appeared weakly, indicating that during an: nealing at 625°C a small amount of transformation took place from the body-centered-cubic to the u phase. However, since all superlattice lines to be expected in the 0 angle range used were actually very clearly present, it was evident that the high temperature body-centered-cubic phase had transformed into a CsCl-type ordered structure before much s phase could form. Reannealing filings for 1 hr at 700°C resulted in complete transformation into the u phase. After 1 hr at 650°C the transformation into IT was not quite complete, the strongest body-centered-cubic diffraction lines were still present, although fairly weak, and only the (100), super-lattice line was detectable (extremely weak). These findings not only confirm the previous conclusionsL as to the existence of a CsCl-type ordered structure in the Fe-V system, but they also indicate that this metastable ordered structure forms at about 600°C preceding the formation of the stable s phase, while at 1250°C the disordered body-centered-cubic phase is stable. The faint (loo) , super-lattice line previously observed in specimens quenched from 1200°C was probably due to the fact that the quenching of the powder in an evacuated fuse:! quartz capsule was not fast enough to prevent completely the ordering reaction on cooling. The present results conform with the suggestion that the A-B bond, in relation to the A-A and B-B bonds, increases in strength from CrFe to VFe to TiFc. It is, therefore, of interest to compare the measured values of the average atomic diameter for these three alloys with the corresponding average atomic diameters calculated from the atomic radii of the elements concerned. ASSUming A-B contacts

Jan 1, 1958

By W. L. Finlay

Size effects in quenching steel are particularly prominent and well recognized because of the existence of a critical cooling rate separating nuclea-tion and growth transformations, as exemplified by the formation of pearl-ite, from the shear type of transformation characterizing the martensite reaction. The absence of a similar, sharply demarcating cooling rate is characteristic of precipitation hardening systems and size effects in these are correspondingly less prominent. This paper is concerned with a size effect in high-purity, precipitation-hardenable alloys which appears not to have been recognized previously. This effect is believed to result from the thermal fluctuations which inevitably occur in quenching a specimen of finite size into a cooling liquid rather than from the existence of a critical cooling rate. QUENCHING "ANOMALIES" The precipitation hardening literature contains many references to so-called anomalous quenching and aging results. By "anomalous", investigators usually meant that their alloys did not consistently harden on aging after quenching according to some anticipated pnttern: not infrequently virtually no age hardening occurred with compositions known to be precipitation-hardenable. Perhaps the most prominent series of anomalies was reported over a 15-year period by Gayler and coworkers on aluminum-copper.l,2,3,4 Working with silver-rich copper alloy, Cohen5 secured some very interesting Rockwell F hardness changes of from 1-5 Rockwell points between the first peak and valley. Fink and Smith borrowed one of Cohen's specimens and, following his heat treatment and quenching practice to the letter, secured6 very different results in which only one peak was obtained and in which the hardness level at the aging lime of Cohen's first peak was 20 Rockwell F points higher. Fink and Van Horn7 encountered serious deviations in age-hardening high purity aluminum-zinc alloys. They stated that "the discrepancies were larger than might be expected from possible experimental errors in the Brinell readings." Geisler, Barrett and Mehl8 likewise encountered anomalous hardening results in aluminum-silver alloys, securing quite different age-hardening curves from two identical specimens. They stated that "the treatments of these samples had been the same, so that the different behaviors could be attributed only to accidental variations in the quenching practice."

Jan 1, 1950

By J. F. Enrietto

It is shown that one cannot approximate the broad internal friction Peaks observed in the Fe-Mn-N system as the sum of a number of subsidiary Peaks and still vetain the concept of a single relaxation time. Furthermore, the approximation of manganese affectirg only nearest neighbor interstitial sites is shown to be incompatible with the experimental results. The results of this experiment show that the influence of manganese in the ferrite lattice extends over 3 to 4 atomic distances. NUMEROUS experiments have shown that the presence of relatively small amounts of substitutional alloying elements can profoundly affect the profile of the damping spectrum in the vicinity of the Snoek peak in bee metals.1-7 Dijkstra and Sladekl observed this phenomenon in Fe-Mn-N alloys where it appeared as a broadening and shifting of the Snoek peak to higher temperatures. The authors interpreted this as being the result of a superposition of two damping maxima—the normal Snoek peak, located at its usual position and having a normal half-width, and an interaction peak having a normal half-width, but occurring at a somewhat higher temperature. They prclposed that the interaction peak was caused by nitrogen atoms jumping from Fe-Mn sites to Fe-Fe sites, the Fe-Mn interstitial sites having one manganese and one iron atom as nearest neighbors, and the Fe-Fe sites having two iron atoms as nearest neighbors. They further suggested that the Fe-Mn sites had a lower energy than the normal Fe-Fe sites because of the presence of the adjacent manganese atoms. From the relative heights of the two postulated damping peaks, the dif-

Jan 1, 1962

By R. L. Smith, J. L. Rutherford

ALTHOUGH considerable effort has been devoted toward the determination of the mechanical properties of pure metals, it is extremely difficult to compare the results of such work. This is because of differences in method and type of test, grain size, heat treatment, and purity of material. There is very little information on the properties of most of the high melting point reactive metals with purities greater than 99.9 pct. Previous evidence concerning the tensile properties of unalloyed metals show that: body-centered-cubic metals are brittle at low temperatures; face-centered-cubic metals remain ductile; some hexagonal metals remain ductile, others become brittle. It may be that traces of impurities decrease the low temperature ductility of the body-centered-cubic lattice. This would suppose that a body-centered-cubic lattice free from impurities would exhibit nearly the same ductility as a face-centered-cubic structure. The present investigation has been an evaluation of the tensile properties of zone refined iron in order to determine whether higher purity material than that previously evaluated behaves differently. Experimental Procedure In this investigation, high purity iron was zone purified using the floating zone method.' The starting stock was obtained from two sources. The first,

Jan 1, 1958

By Arthur Zentner

THE PAST YEAR saw important developments in all the main branches of zinc metallurgy, which can only be douched on briefly here. Vertical Retort Smelting-The New Jersey Zinc Co. reports their operations to be about as last year when the number of vertical retorts at the Palmerton plant was increased from 16 to 28. The first unit of eight vertical retorts at Oker, Germany, to treat the Rammelsburg complex ore was completed early in the year. A second unit has been under construction and is probably ready to start operations about this time. Each unit is rated for 10,000 metric tons of zinc per year. A plant of 40,000 metric tons annual capacity is the goal. A reflux plant was also built to make high-grade zinc. The plant program is being -carried forward with government finan¬cial assistance, as was the case with the electrolytic zinc plant at Magdeburg. Government subsidies cover mining and 'smelting, and allow for depreciation and reasonable return on invested capital, according to U. S. Bureau of Mines reports.

Jan 1, 1938

Institute of Metals Division SAM TOUR, Chairman J R FREEMAN, JR , Vice-chairman ZAY JEFFRIES, Past-chairman C H MATHEWSON, Vice-chairman WILLIAM M CORSE, Secretary-Treasurer 810 Eighteenth Street, N W Washington, D C Executive Committee Until February, 1031 Until February, 1932 Until February, 1933 T S FULLER J L CHRISTIE W M PEIRCE G E JOHNSON ARTHUR PHILLIPS A J PHILLIPS W A SCHEUCH H M WILLIAMS GUY C RIDDELL Research PAUL D MERICA, Chairman S SKOWRONSKI

Jan 1, 1923

U.S. Steel Uncovers Massive Iron Ore Deposits in Nevada United States Steel Corporation has confirmed that mineral investigation in Lyon County, Nevada. has been under way since 1960. Confirmation followed press reports of a statement attributed to a Nevada State inspector of mines to the effect that the Corporation has found a major iron ore deposit that may also contain copper ill West Central Nevada. Drillings over the years in a number of locations have indicated extensive iron ore bodie containing a possible quarter of a billion tons of ore of a basically magnetite composition. analyzing less than 40% iron, which would require beneficiation for commercial use. Some of these deposits are deep- lying while others would permit open pit mining. These bodies contain copper in quantities of approxiimately 0.3%. More recent drilling in another area has disclosed evidence of additional deeply-lying deposits of a lower fe content but with more promising indications of copper. A realistic estimate of fe and cu ore reserves cannot be made until more drilling is completed.

Jan 1, 1970

By Henry G. Morris

The use of compressed air for the transmission of power has reached so great a development that we find numerous large establishments devoted to the manufacture of machinery for its production and application, and special periodicals published for the dissemination of information on the subject. Moreover, its employment is so general in mining operations that no apology is needed for the presentation to the Institute of such a paper as the present. The admirable articles of Mr. E. A. Rix, published in Conzpressed Air, show a wide range in the mechanical efficiency of air-compressors, varying, under different conditions, from 15 to 60 per cent.; and it is evident that any

Jan 1, 1902

THE Boston meeting, August 29-31, was in many ways one of the pleasantest the Institute has enjoyed in years. Much hard work had been done by the committee, and with excellent results. The program had been purposely restricted with the idea that a smaller, more homogeneous audience formed the best basis for a regional meeting, and the event fully justified the plan. The one hundred and sixty-three members and guests attending were dominantly interested in geophysical methods or their application, and, despite the highly technical character of the papers and the unusual heat, attendance and interest in the technical sessions were well sustained. The exhibition of geophysical instruments and aerial maps added greatly to the meeting.

Jan 1, 1928

By Ralph Sweetser

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, Ill., on Oct. 1, 1935. PROCEEDINGS R. H. SWEETSER,* New York, N. Y.-Seven years ago last June 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 tech-nical secretary. J. T. MACKENZIE, t Birmingham, Ala.-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 com-plaints 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 prin-ciples 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.

Jan 1, 1936

By Chas. Y. Clayton, Francis B. Foley, W. E. Remmers

DuRing the summer of 1919, the late Dr. Henry M. Howe, then Chairman of the Division of Engineering of the National Research Council, organized a committee to obtain a better insight into the behavior of carbon steels under the influence of various treatments by a proper control of the time and temperature factors. During part of 1919 and 1920, work in connection with this investigation was carried on at Dr. Howe's laboratory at Bedford Hills, N. Y. During 1921 there was an enforced hiatus in the work, occasioned by the illness which resulted in Dr. Howe's death in 1922. At that time one of the present authors compiled the results of the work which had been done and this was published in 1923.' Following the publication of this work, it seemed desirable to carry on in the same manner an investigation of steel of C 0.75 per cent., which steel had not been as fully treated as had the other steels of C 0.34 and 0.52 per cent., used in the published work. Furthermore, certain unusual results have been obtained in the treatment of C 0.52 per cent. steel by quenching and drawing, and repetition of this part of the work seemed advisable. This has been done during the past year at the School of Mines and Metallurgy of the University of Missouri at Rolla, Mo., by a cooperative undertaking of the School and the Bureau of Mines, working in conjunction with the Committee on Heat Treatment of Carbon Steels of the National Research Council. The present paper is a report of the results obtained in this work.

Jan 1, 1926

By Frank L. Hess

BERYLLIUM is demanding more of the limelight, and the output of beryllium copper (containing 2% to~ 3 per cent of beryllium) seems to have grown 60 per cent above that of 1936, which was double that of 1935. There is increasing interest in beryllium-aluminum alloys and small quantities are being marketed at $50 per lb. for the contained beryllium. Other alloys also can be produced. Further price decreases for beryllium copper (now $23 per lb. for the contained beryllium) seem , possible and desirable. No difficulty has been experienced in obtaining beryl and a 'reserve stock has been built up. One supplier heretofore found reliable has offered to furnish 200 tons per month. Supplies during 1937 have come from the Black Hills in South Dakota, Colorado. India, and South America

Jan 1, 1938

By S. E. Bronisz, R. E. Tate

s-plutonium samples possessing a strong growth texture have been produced by allowing them to transform under pressure from p to a. A fiber texture with [010] parallel to the pressure axis results. The textured samples are expected to be useful in determining the effects of crystallographic orientation on the physical properties of a plutonium, and initial results of measurements of resistivity and mechanical properties are described. THE crystal structure of a plutonium1 is mono-clinic, P21/m, and many of the metal's properties should reflect the crystallographic anisotropy. Unfortunately, it has not yet been possible to grow useful sizes of single crystals of a plutonium. Therefore, few of plutonium's orientation-sensitive properties have been determined as a function of crystallographic orientation. One way to gain information about at least some of the orientation-dependent properties is to study a highly textured sample. Such samples have been produced by cold rolling a plutonium,2 but they are necessarily very small in one dimension. We have now successfully used two other techniques to produce highly textured samples, not limited to small thicknesses. METHODS OF PRODUCING PREFERRED ORIENTATION The texture is produced by causing the plutonium to transform from ß to a while under pressure. It was observed by Gardner3 that applying a compres-sive load during the transformation resulted in the formation of columnar grains of a plutonium, and Cramer4 observed a similar structure in some diffusion couples rolled in the P phase. Neither of these workers, however, investigated the subject beyond these observations. The more flexible of the two methods developed is that of compressive loading. The technique is to enclose a sample of plutonium in a die assembly before applying the load. It is possible, of course, to dispense with the die and simply press the sample between two platens. In this case, however, the unrestrained sample deforms during the pressing, making it difficult to maintain the load and to control the final sample thickness. This compressive loading technique has been used on specimens ranging from 1/4 to 3 in. diameter, with height-to-diameter ratios ranging from 5 : l to 1:6. The procedure begins with loading the sample, a right cylinder of a plutonium, into the pressing die. Plastic deformation of the sample while it is being pressed is minimized by machining the sample so that its diameter is nearly the same as that of the die barrel. Then the loaded die assembly is placed in a vacuum pressing can that fits on a hydraulic press. After a vacuum is achieved the die assembly is heated to 180°C and equilibrated. The load is then applied and the specimen and die are allowed to cool to about 40° to 50°C before the pressure is removed. The resulting sample is composed of rod-shaped a -plutonium grains, the rod axes being parallel to the cylinder axis and the pressing direction. Photomicrographs of the oriented structure are shown in Fig. 1. Although most of the specimen is composed of grains whose rod axes are parallel to the cylinder axis, a thin, peripheral layer consists of rod-shaped grains whose rod axes are perpendicular to the cylinder axis. Presumably, the highly plastic nature of p plutonium leads to approximately hydrostatic conditions during the initial stages of the P — a transformation under pressure. At this time, the grains in the peripheral layer would have grown parallel to the local force direction. During the latter stages of the transformation, the accompanying volume contraction would have eliminated the radial forces, leaving only the axial force and resulting in the growth of the observed structure. The growth texture did not form without the application of pressure. Attempts were made to produce the texture by repeating the standard temperature cycle without

Jan 1, 1965

By Joseph B. Darby, Paul A. Beck

IN isothermal sections of several ternary systems, the a-phase was found1 to extend in the form of a relatively narrow elongated field, connecting the U-phases that are present in the adjoining binary systems. This was interpreted in accordance with the conception that the U-phase is an electron compound and the ternary U-phase fields were shown in several systems' to extend approximately in the direction of constant average d-shell electron vacancy number per atom. ' However, in the various isothermal sections of the Fe-Cr-Mo system" the ternary a-phase field was

Jan 1, 1958

By Herty, C. H.

Iron oxide (FeO) plays an extremely important part in the manufacture of iron and steel. In the three major processes- blast-furnace, open-hearth, and Bessemer converter-iron oxide is the chemically predominant compound and controls to a large ex- tent the operation of the furnaces and the composition and quality of their respective products. In order to emphasize the importance of iron oxide in each process, they will be considered individually in some detail. THE OPEN-HEARTH FURNACE. Iron oxide is introduced into the open-hearth furnace in four ways : 1. The scrap charged into the open hearth is oxidized by the furnace gases, the amount of oxide formed depending primarily on the amount and type of scrap charged. It has been found' that with large scrap, 1.7 Ib. of FeO is formed per 100 Ib. of scrap charged, whereas with scrap of medium size about 5.3 Ib. of FeO is formed per 100 Ib. of scrap charged, when the period between the charging of the scrap and the addition of hot metal is 3 hours. 2. The decomposition of the limestone sets free CO, by the reaction

Jan 1, 1957

By William P. Blake

(Canal Zone Meeting, November, 1910.) A DEPOSIT of manganese-ore near Tucson, Ariz., merits notice by reason of the peculiar form in which it occurs, and as a striking. example of ore-deposition by vadose upward capillary flow of metal-bearing solutions with concentration at the surface of the country-rock. This deposit occurs at the northern end of the Coyote mountains, about 40 miles west of Tucson, upon the outcropping beds of porphyritic rock, which appear to be partly-metamorphosed strata of volcanic tufa, probably of late Secondary or of Tertiary age. The strata dip northward at a low angle, and present a series of basset-edges in parallel lines of outcrop, east and west, facing the south and extending over many acres. Successive groups of these outcrops, from 5 to 20 ft. in breadth, are coated with oxides of manganese in lustrous black films and crusts, shining in the sunlight like polished ebony, and covering the whole surface of the rock above the soil. Seen at a little distance, these croppings look like solid ledges of massive and pure ore; but closer inspection and a few blows of the hammer reveal their true nature as a superficial coating allied in origin to the blackened shining surface of rocks exposed in desert-regions, familiarly known as " desert paint" or "desert varnish,"' similar to the phenomena described by me in a former paper, but much thicker and heavier. * By reason of the death of the distinguished author, this communication, probably his last communication to technical literature, is published without revision of the proofs by him. A term first given y G. K. Gilbert. See Rocks, Rock-Weathering, and Soil; by George P. Merrill, p. 256 (New York, 1897). Superficial Blackening and Discoloration of Rocks, Especially in Desert Regions, Trans., xxxv., 371 (1905).

Sep 1, 1910

By J. E. Breen, J. Weertman

The creep rate of polycrystalline tin was studied as a function of temperature and stress in constant stress experiments. The temperature was varied from room temperature to almost the melting point of tin. Activation energies were calculated from tests run at the same stress. It was found that on a log creep rate vs inverse temperature plot the experimental points did not fall on one straight line but on a line which changed its slope in the 90° to 160°C region. Two activation energies for the creep of tin can be calculated from the data: a value around 26,000 cal per mol at high temperatures and a value around 11,000 cal per mot at low temperatures. It is suggested that the discrepancies between the creep activation energies and those of self-diffusion can be accounted for if self-diffusion takes place predominately by Zener's ring mechanism rather than through vacancy or interstitial movement. SHERBY, Orr, and Dorn' and Dorn' have recently reviewed some of the data on high temperature creep of metals. -The data show that the activation energy of high temperature creep is approximately equal to the activation energy of self-diffusion. This same correlation has also been successfully made between the activation energy of grain boundary relaxation and that of self-diffusion.3,4 The metal tin does not fit into this simple picture. Its activation energies of self-diffusion differ appreciably from that of grain boundary relaxation and of creep. Fensham,5 from a precisely performed experiment, has determined that the activation energies of self-diffusion of tin are 10,500 and 5,900 cal per mol along the C and A axes, respectively. There are two energies because of the anisotropic nature of tin. Rotherham, Smith, and Greenough6 have shown that the grain boundary relaxation activation energy is 19,000 cal per mol (measurements made from room temperature to 100°C). Puttick and King7 found the same activation energy for grain boundary slip in bicrystals of tin (180° to 225°C region). Until recently, there was no high temperature large strain creep data on tin suitable for activation energy calculations. At rather small strains (up to 0.01), Tyte8 had made a series of measurements on tin from which activation energies can be calculated. In Fig. 1 are plotted some of his data on a log creep rate vs inverse temperature graph. It can be seen that Tyte's work indicates that at a relatively low temperature the activation energy is around 7,400 cal per mol but at higher temperatures the activation energy increases. Since Tyte measured the creep only for small strains, it is doubtful if a

Jan 1, 1956

By R. J. Wysor

J. S. UNGER, Pittsburgh, Pa.-On page 22 reference is made to 36 carloads .of dust shipped. Did the material in that last sample come from a; furnace running on pig iron, ferro alloys, or spiegel? R. J. Wysor.-Pig iron; we have not made any ferro alloys; or spiegel at Bethlehem in the last 3 years. J. S. UNGER.-DO you use domestic or foreign ores? R. J. WYSOR.-In regular practice, largely foreign ores. J. S. UNGER.-How much per unit does it cost to produce that? R. J. WYSOR.-You might say it does not cost anything; we do not change our blast-furnace practice at all to obtain the dust. Although it has been a profitable byproduct, I would rather not have it unless we could reclaim it on a large scale, as we would have better working stoves. J. S. UNGER.-Does the trade take it as readily as natural salts? W. J. WYSOR.-The fertilizer dealers have been anxious to get it. This did not happen, however, until the war started. J. S., UNGER.-They have been willing to take anything since the war started. R. J. WYSOR.-Yes. However, we could have sold the material before the war; in fact, about 4 years ago, we had a contract ready to sign, but we did not think it would pay us to bother with it then. W. H. Ross, Washington, D. C.-We of the Fertilizer Division of the Bureau of Soils have been particularly interested in Mr. Wysor's investigations on the possibilities of recovering potash from the blast furnace, and we look upon the results he obtained as among the-most important that have yet appeared on the subject of finding new sources of .American potash. About 5 years ago we undertook a corresponding investigation on the recovery of potash in the cement industry. Representative samples of raw mix and ground clinker were collected from the different cement plants in this country with a view to analyzing each sample for potash. With the data thus obtained and knowing the ratio between the raw mix and the cement produced and the output of the latter, we thought it possible to calculate approximately for each plant the quantity of potash that escapes daily from the kilns. After partly completing the work, however, it had to be abandoned for a time. It was again taken

Jan 4, 1917

By M. M. Neale

The pottery department has been aptly described as the "heart of the zinc plant," md every operator of a horizontal-retort plant is acquainted with the fact that good retort practice is the keystone of the smelting process. Since retorts and condensers are clay products, it is obvious that improvements in other branches of the ceramic industry should be observed for possible adoption in the pottery process for zinc smelting. Deaeration of clay bodies is one of the improvements that have become fully, established in many brick and pottery plants. Our investigation of a number of these installations always yielded the same answer—improved practice. Improvement in workability, elimination of laminations, less porosity, greater wet and dry strength, were among the claims put forth for this process. All of these features are exceedingly desirable characteristics in the manufacture of a zinc retort. A preliminary test, which involved truck transportation of deaired slugs over a relatively long distance, did show the value of many of these characteristics in forming the retort. Results from the standpoint of , longer retort life in the smelting furnace were not outstanding. The idea lay dormant for several years but was revived again in 1940, when it was decided to make whatever changes were necessary in the equipment for pottery manufacture to fully demonstrate the process. A number of the manu- facturers of machinery for clay work were asked to submit proposals, and the plan finally adopted was extremely simple and economical. Machine FOR DeaeRRATING Selection of the ''Straight-line'' principle for conversion of the "Wettengel" pug mill to a ''vacuum-extrusion" machine preserved some usable parts of the original equipment, such as the drive mechanism, and main shaft. The converted machine consists of a feed hopper, a compression and shredding zone, a vacuum chamber, and an extrusion barrel, as shown in Fig. I. In operation the clay mix travels from the feed hopper into the compression zone, where it is compressed and finally forced around the tapered cone into the vacuum chamber. As it enters this chamber the clay body is shredded into thin plates, for exFosure to the vacuum. The shredder consists of a hub mounted on the main shaft, to which are bolted segmental sections, each of which carries shredder knives. The compression zone and extrusion barrel function as seals for the vacuum chamber and the shredded clay mix is agitated thoroughly during its exposure to the vacuum. A vacuum pump, equipped with a 3-hp. motor, is attached to this chamber, and maintains 25 to 26 in. vacuum during operation of the mill. Changes in Practice Prior to the adoption of the deaeration process, our standard pottery practice called for double mixing in the combination 7

Jan 1, 1944

By F. H. Buttner, E. R. Funk, H. Udin

A. P. Greenough (University College, swansea, Great Britain)—I have recently made some experiments on the deformation of silver wire at high temperature in an atmosphere of oxygen-free nitrogen. The observa-tions which 1 made confirm the main conclusion of this paper, that the most satisfactory mechanism so far suggested to explain the deformation which takes place

Jan 1, 1953