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By Hal M. Lewers

IN the past few years and especially since the beginning of World War No. 2, gold has attained a new, important. and critical place in the international scene, and in world affairs. In the past, as far back as history records, most wars have been waged for the purpose of acquiring it from someone else by conquest. But now, the most titanic struggle of all time is being waged with the avowed purpose of not only destroying it, but of destroying all that it stands for and represents. A tradition dating back to ancient Rome, affirms that battles are fought by men with weapons, but wars arc eventually won by gold. The validity of that tradition is now being subjected to its major test. Hitler has proclaimed that in his new world order, the work dollar or reichsmark, a beautifully engraved paper currency representing only a theory of value, based on unit of work and production, will become the supreme medium of world exchange, and that gold eventually will he valueless and obsolete.

Jan 1, 1942

OF the many categories into which scientific knowledge has been arbitrarily 'divided, the one that has proved most. applicable in our attempts to gain an insight into the details of steelmaking processes is physical chemistry. To the young metallurgist who has only recently survived a college course in this subject, the application of its principles to reactions in liquid steel should not be difficult. The many excellent textbooks of physical chemistry provide ample material on the principles of this subject for the student of steelmaking processes. It is the purpose of this chapter to provide a concise review of the principles of physical chemistry that have proved useful in studies of steelmaking and at the same time to present some of the data that are essential to the application of physical chemistry to reactions at high temperatures. Certain parts of physical chemistry require rather formidable mathematics for their complete development, but in the main those applications in which we are here interested can be expressed in fairly simple terms. Many of the equations are logarithmic, and we shall use the symbols In X and log X to represent, respectively the natural and the common logarithm of X. The two are related-by In X = 2.303 log X. Logarithms may, be read from a good slide rule with sufficient accuracy for our purposes. In a few spots a knowledge of the calculus will be helpful. MATTER Innumerable forms of matter may, be recognized, and these may be converted by chemical processes into others, as ore, coke, and air are converted into iron, slag, and gas.. Whenever such a change occurs there is a corresponding change in the amount of energy associated with the matter. The process may require an input of energy, as in the electrolytic production of aluminum, or it may result in an output of energy, as in the combustion of fuel. The basic laws of the conservation of matter and of energy tell us that we cannot change the total amount of matter or the total amour t of energy.. When the fuel pile is used up, we realize that it has simply been converted into other forms of matter; .i.e., ash

Jan 1, 1964

By Milton T. Pana

Computer techniques now have been applied to the solution of a wide variety of scientific and engineering problems in the mining industry, but generally not in great depth in any one area. In mining, the area covered in greatest depth and with the greatest success has probably been mine planning and to a lesser degree production scheduling. A rather comprehensive review of the literature related to mine planning and production scheduling indicates that contributions in these areas have been geographically, as well as organizationally, widespread. Of twenty-six papers reviewed, eleven were from industry, eight from educational institutions, four from computer vendors, two from the Bureau of Mines, and one from a private consultant. The conclusions that can be derived from the literature are: First, the-state-of-the art has advanced to the point that computing ore reserves and developing mining plans with the aid of the computer is now a routine practice; second, the application of the computer to mine planning problems has markedly improved our ability to estimate ore reserves, more accurately define pit limits, and determine an optimum mining sequence. MINE PLANNING The papers in this section deal essentially with the problem of determining the final pit limits of an orebody and the ore reserves associated with a given pit limit. The problem is probably best described by Soderberg25 and more recently by Reibell. 23. There are two techniques currently being applied to this problem by several mining companies: 1) the multiple-cone technique and 2) the Lerch-Grossman algorithm. The multiple-cone technique is the older of the two techniques and has the advantage of being more flexible, allowing an engineer to easily vary pit slopes in different sectors of the design. The technique can also be used to define intermediate pit contours. The Lerch-Grossman algorithm is appealing in that the final solution is given in the form of a true mathematical optimum. The technique is limited, however, in that the size of the blocks in the orebody model are a function of the desired

Jan 1, 1969

By HUNTINGTON ADANS

(Wilkes-Barre Meeting, June, 1911.) THE arrangement of a flow of cyanide-pulp through Pachuca tanks in agitation, so as to permit a continuous process, instead of alternate filling, agitation, and emptying, has been proposed by various writers within the last two years, and more particularly by A. T. Grothe, agent for the Brown patents on Pachuca tanks in Mexico. It was first put into practice, I believe, by M. H. Kuryla at the Esperanza mine in El Oro, Mexico. The starting of agitation in Pachuca tanks after filling may offer no serious difficulties with ores which do not settle rapidly in such tall tanks; and the adaptation of the tanks to continuous agitation under such conditions may give simply a somewhat more convenient method of treatment and greater agitation-capacity for a given number of tanks, because of the saving -of time lost in filling and discharging. But in the treatment .of pulp which tends to settle rapidly, as in the cyaniding of concentrates or of the whole pulp of ores containing heavy sulphides, the packing of the slime at the bottom may, cause much trouble. The use of the radial air-pipe attachments near the top of the cone and of the air-valve outside of the air-lift .tube at the bottom may obviate the difficulty to some extent; but the action of the radial air-pipes on the cone-sides is that -of a sand-blast, and their continuous use cuts through the tanks. Moreover, even when these pipes are used, some pulps will pack tightly below them in the cones. Under such conditions the use of Pachuca tanks with intermittent filling and discharging becomes a troublesome process. Time is lost in ,starting agitation; large quantities of compressed air are wasted; pulp is blown over the tank-tops; and not infrequently it may be necessary to dig out the bottoms of tanks by hand. This trouble is the only important one occurring in the use of Pachuca tanks; and, since it is caused by intermittent filling, the .arrangement of a continuous flow of pulp from tank to tank,

Aug 1, 1911

By Oscar Kuchs

IN January and February of the current year, at the Tooele plant of the International Smelting Co., Tooele, Utah, a modification of the usual method of converting, for the treatment of copper-lead matte from lead blast- furnaces, was developed and put into successful operation. In brief, the method consists in blowing molten matte direct from the blast furnaces in basic-lined converters, without the addition of siliceous fluxing ores, to the almost complete elimination of the lead contained, and to the production of copper bullion, the resulting lead fume being recovered by the filtration of the converter gases through woolen fume bags. The process is carried out in conjunction with the converting of reverberatory copper matte, the heavy iron slag, together with the copper precipitated, being transferred to converters blowing copper matte. The purpose of this transfer is to reduce the copper oxide formed, due to the necessary overblowing of the lead-matte charge, and to utilize, as far as possible, the value of iron from the lead matte, for the fluxing of siliceous dry ores. The final slag from the copper converters is then skimmed off and transferred molten to a reverberatory smelting furnace treating copper ores. This variation from general converting practice was the outgrowth of results obtained during 1913 when it was endeavored to convert copper-lead matte in the usual manner, with the direct addition of siliceous fluxing ores. To make clear the reasons lying back of the process it is necessary to recount at some length the results of operations during that year. In the design of the lead plant it was planned to treat the copper-lead matte from the furnaces by direct converting without reconcentration and thereby to recover the copper, silver, and gold as quickly as possible. A converter plant of ample capacity, treating copper matte, already being in operation, it was only necessary: to install a bag house, a fan, and the necessary flues to complete the equipment.

Jan 7, 1914

By Charles H. Fulton

THE Engineering Education group began its sessions Tuesday morning, Feb. 16, as a Committee and wound up the day as the Institute's fifth " Division." C.II. Fulton presided. The first paper for discussion was entitled "Teaching Management in Engineering Schools,"' by Eugene McAuliffe, president of the Union Pacific Coal Co., space for which may be found later in these pages. In it, Mr. McAuliffe argued that an engineering student should be taught the knowledge of men, much as a medical school teaches surgery. He then went on to indicate, out of the wealth of his administrative experience, the problems an executive needs to be equipped to handle, and said that every student engineer should look on himself as a potential manager.

Jan 1, 1932

By Ned Kuenhold

AN equipment manufacturer swallows a bitter pill when he sees his machinery improperly in- stalled and not used to the full potential. This frequently happens with vibrating screens. Screens can be classified according to the path of vibration imparted to the screen surface. On this basis there are: 1) vertical circle or modified circle throw, 2) horizontal circle or modified circle throw, 3) vertical linear reciprocation, 4) tilted linear reciprocation, and 5) horizontal linear reciprocation. The most versatile vibration for medium to coarse sizing is generally conceded to be the vertical circle produced by an eccentric or unbalanced shaft, but other types of vibration may be more suitable for certain screening operations, particularly in the finer sizes.

Jan 6, 1957

By James Norman, Benjamin S. Lindsey

BaritE (BaSO4) is the most important industrial barium mineral from the standpoint of quantity consumed. In 1938 the amount was 365,000 tons. Its uses are numerous, some of the 'more important being in the production of pigments, as an inert filler in a wide variety of products, as a weighting material in oil-well drilling muds, in the manufacture of some kinds of glass, and in the production of barium chemicals. The barite studied in this investigation occurs as the massive variety in a shale replacement formation near Magnet Cove, Ark. It is intimately mixed with quartz and small amounts of iron oxide and residual shale. Complete liberation of barite and quartz is not obtained when the rock is ground to 100 per cent through 325 mesh. The crude rock with which all test work was done assayed 85.1 per cent BaSO4, II.II per cent SiO², and 2.85 per cent R²O3. Its specific gravity was 4.03. It was found in the course of the investigation that the barite contained a small amount of uniformly distributed carbonaceous material, so intimately dispersed that it could not be seen with the microscope, but gave a definite gray cast to the barite concentrates. The color of the barite in polished sections of the crude rock ranged from gray to almost black, while finely ground powder was a reddish gray. The reddish hue was due to the iron oxide present. In 1939, under the supervision of Oliver C. Ralston,* the Bureau of Mines, in cooperation with the Milwhite Company, of Houston, Texas, undertook to study the flotation of barite from Magnet Cove, Ark. Flotation of several southern barite ores had already been investigated by the Bureau of Mines.' The Magnet Cove barite was unique, however, in that it had to be ground to such an extremely small particle size for liberation. The flotation of non-metallic minerals in the presence of a large amount of slime is usually very difficult, and when done is an innovation calling for conditions different from those under which granular material is scparated. Laboratory Flotation Work Preliminary investigation showed that the flotation reagents recommended by O'Meara and Coe1 for separating barite and siliceous material were suitable, but much larger quantities of reagents were required to separate such finely divided material. Moreover, it was found that careful control of the frothing was necessary. When oleic acid and sodium silicate were used a voluminous froth was observed at the beginning of a test, and toward the end there was not enough froth to effect complete recovery of barite. The addition of pine oil as a frother gave proper frothing for the duration of the test, and the substitution of coconut fatty acid (crude lauric acid) for oleic acid produced a more heavily burdened froth. Two different paper-mill fatty-acid products were tested

Jan 1, 1942

By Benjamin S. Lindsey, James Norman

BaritE (BaSO4) is the most important industrial barium mineral from the standpoint of quantity consumed. In 1938 the amount was 365,000 tons. Its uses are numerous, some of the 'more important being in the production of pigments, as an inert filler in a wide variety of products, as a weighting material in oil-well drilling muds, in the manufacture of some kinds of glass, and in the production of barium chemicals. The barite studied in this investigation occurs as the massive variety in a shale replacement formation near Magnet Cove, Ark. It is intimately mixed with quartz and small amounts of iron oxide and residual shale. Complete liberation of barite and quartz is not obtained when the rock is ground to 100 per cent through 325 mesh. The crude rock with which all test work was done assayed 85.1 per cent BaSO4, II.II per cent SiO², and 2.85 per cent R²O3. Its specific gravity was 4.03. It was found in the course of the investigation that the barite contained a small amount of uniformly distributed carbonaceous material, so intimately dispersed that it could not be seen with the microscope, but gave a definite gray cast to the barite concentrates. The color of the barite in polished sections of the crude rock ranged from gray to almost black, while finely ground powder was a reddish gray. The reddish hue was due to the iron oxide present. In 1939, under the supervision of Oliver C. Ralston,* the Bureau of Mines, in cooperation with the Milwhite Company, of Houston, Texas, undertook to study the flotation of barite from Magnet Cove, Ark. Flotation of several southern barite ores had already been investigated by the Bureau of Mines.' The Magnet Cove barite was unique, however, in that it had to be ground to such an extremely small particle size for liberation. The flotation of non-metallic minerals in the presence of a large amount of slime is usually very difficult, and when done is an innovation calling for conditions different from those under which granular material is scparated. Laboratory Flotation Work Preliminary investigation showed that the flotation reagents recommended by O'Meara and Coe1 for separating barite and siliceous material were suitable, but much larger quantities of reagents were required to separate such finely divided material. Moreover, it was found that careful control of the frothing was necessary. When oleic acid and sodium silicate were used a voluminous froth was observed at the beginning of a test, and toward the end there was not enough froth to effect complete recovery of barite. The addition of pine oil as a frother gave proper frothing for the duration of the test, and the substitution of coconut fatty acid (crude lauric acid) for oleic acid produced a more heavily burdened froth. Two different paper-mill fatty-acid products were tested

Jan 1, 1942

[Executive J. V. W, REYNDERS, Chairman SYDNEY IL BALL E, DEGOLYER WILLIAM H. BASSETT SAMUEL A. TAYLOR Finance GEORGE D, BARRON, Chairman H. A, GUESS GEORGE OTIS SMITH Membership J. DI, CALLOW, Chairman GEORGE D, BARRON WILBER JUDSON JOHN A. CHURCH, JR. H, N. SPICER Alternates LEWIS W. FRANCIS LOUIS D, HUNTOON F, T. RUBIDGE]

Jan 1, 1928

By A. A. Steel

(Spokane Meeting, September, 1909.) DURING. the summer of 1905 I was employed by the U. S. Geological Survey to investigate the geology, Mining, and preparation of barite in most. of the fields of the United States. The Eastern districts have been more or less completely described ; the Virginia field in detail by Thomas L. Watson, in his paper, Geology of the Virginia Barite-Deposits,' and other fields in abstract., including statistics of production and references to current literature, by various authors .2 There have also been published a few details of the occurrence of barite in the lead-mines of Washington county, Mo.3 The other accounts of this district are erroneous and meager, and since this field is the most important one in the United States at the present time, a detailed description of the local geology seems doubly desirable. Barite-deposits are scattered over nearly the whole of Washington and adjoining counties, but. the product, is all mined from the areas indicated upon the sketch-map, Fig. 1, and is shipped from the stations of the St. Louis, Iron Mountain &. Southern railway, between Blackwell and Potosi, from 45 to 60 miles SW. of St.. Louis. The topography is for the most part gently rolling, with slightly graded streams, usually less than 200 ft. below the higher hill-tops. Along Mineral fork and Indian creek are :some steep bluffs and cliffs, affording good exposures of the

Feb 1, 1910

By L. S. Richardson, N. J. Grant

REACTIONS of oxygen and nitrogen at low pressures with titanium have recently been studied by a number of investigators.1-3 Gulbransen and Andrew' noted that the reaction with nitrogen followed the parabolic rate law whereas the reaction with oxygen deviated slightly from this law in the temperature range 300° to 800°C. In the work reported here, commercial titanium (75 A) was used as the test material. Cylinders 2.5 in. long and 0.25 in. in diameter were machined from heavier bar stock. The test pieces were given a metallographic finish, immersed for 30 min in cold concentrated HC1, washed in water, then acetone, and dried with lint-free cloth. Reaction rates were determined in a modified Sieverts type apparatus by measuring the decrease in gas pressure of the reacting gas contained in a constant volume. The amount of gas added could be measured in a calibrated gas burette to an accuracy of 0.01 mm. During the course of a run the temperature never varied by more than 10°C and then only for brief moments. After placing the specimen in the furnace, the system was first evacuated for 12 hr at room temperature, and then flushed with purified argon five times, adsorbed gases being discharged during this period from the glass system with a high frequency spark coil. The flushing and discharging were repeated at 400°C. This rather involved procedure was found necessary after a number of trial runs indicated extraneous effects traceable to the system. Reaction periods up to 2 hr were used, at initial gas pressures of 0.2 to 0.5 atm. Experimental Results Fig. 1 shows the decrease in oxygen pressure for tests at 0.5 atm at various temperatures as a function of the square root of the time. Deviations from linearity are minor and the parabolic rate law is obeyed. Fig. 2 shows the same plot for the nitrogen reaction. A definite deviation from linearity is noted; however, it is probable that the higher initial rates are caused by the presence of small amounts of oxygen contamination, the initial faster rate changing to the slower rate after about 5 to 10 min. Calculations of the rate constants were made on the basis of the latter portion of the curves. The parabolic rate law constants calculated from these curves are shown for oxygen and nitrogen in Fig. 3. In spite of some scatter the average curves are quite definite. Changes in gas pressure of the order of 20 pct did not result in a measurable change in the rate law constants. The activation energy for the oxygen reaction was calculated to be 47,400 cal per mol (above 700°C), which is not in agreement with the value quoted by Gulbransen and Andrew' for lower temperatures, their value being 26,000 cal below 600°C. The activation energy for the nitrogen reaction was calculated to be 45,400 cal per mol above about

Jan 1, 1955

By Rollin A. Pallanch

THE Midvale mill of the United States Smelting Refining and Mining Company is situated on a flat site whose elevation is 50 ft above that of the Jordan River. Tailings are impounded in the area between the river and the flat upon which the mill and railroad switchyard are located. The water supply is pumped from the Galena canal which leads from the river at a point some ten miles to the south. The mill has a present capacity of approximately 1700 tons daily. It started out originally in 1926 as a 750 ton three-unit plant. The tonnage was gradually increased to 1200 tons by 1934, and in late 1935 a fourth unit was added. The accompanying flowsheet shows the principal equipment and how it is utilized. The ore is principally sulphide with varying degrees of oxidation, with individual lots ranging widely in both precious and base metal content. In each of the four individual units of the mill there will often be mixtures of as

Jan 1, 1948

By John R. Freeman

The die pressing of brass may be described as a method of producing irregularly shaped parts of brass and other copper alloys by hot deformation in a die under pressure. Die pressing of brass was first developed as an improvement on sand castings in order to obtain irregularly shaped articles of brass with superior surfaces, a closer tolerance in dimensions, a denser structure, freedom from porosity and elimination of the relatively large amount of scrap invariably attached to sand castings. The freedom from sandy surfaces with consequent greater tool life in machining operations was also recognized as well as elimination of losses due to the uncovering of blowholes in machining operations. Die pressing also gave alloys of superior strength. Die pressings today are made from extruded rod or shapes, according to design of the part to be made. The greater number of pressings are made from round rod, because of its relatively lower cost and ease of handling. The rod is first sheared or sawed into desired lengths, the diameter of rod used and length of "slug" or "rivet" depending upon ultimate weight and shape of the die-pressed part to be made and design of die. The dimensions of the slug are figured so as to give the minimum amount of scrap to be sheared from the pressing as it comes from the die. Extruded shapes having I, T or X sections are often used when the finished part is to have a similar shape or heavy sections are joined by relatively light sections of considerable length. A rod bent in the shape of a U is also used on occasion, for similar reasons. Proper shearing of the slugs is of considerable importance. The sheared ends of the slugs should be as flat and straight as possible. Improperly sheared ends having an angle to the axis of the bar or a rough, uneven surface are liable to give folds or laps in the finished pressing and proportionately high rejections. The property of shearing varies considerably with different alloys and should be considered in the selection of a material for a given part. Where satisfactory shearing is not possible, the slugs may be cut from the bar by power saws. Extruded

Jan 1, 1931

By Rex O. McLellan

The formation of a monovacancy in a metal is simulated in an elastic model by the displacement of the surface of a small spherical cavity in a large elastic continuum. The application of linear elasticity to this distortion results in a well- known formula for the energy and an expression for the concomitant entropy change due both to the shear strain in the continuum and also to the dilation of the solid resulting from the boundary conditions at the surface of the solid. Elastic data (the sliear modulus and its temperature coelficient) are used to calculate the entropy and energy of formation for many metals. Despite the simplicity of the assumptions involved, the agreement between the calculated entropies and energies and experimental values is remarkably good. In recent years there has been a large increase in measurements of the absolute concentration of mono-vacancies in metals as a function of temperature. Hence new data for both the energy and the noncon-figurational entropy of formation of monovacancies has become available. Recent measurements&apos; of the anomalous (non-Arrhenius) self-diffusion in many bcc metals has also focused interest on the prediction of the thermodynamic parameters of mono- and multi-vacancies in those metals for which no data are available. Damask and Dienes&apos; have discussed the various theoretical calculations of the energy of formation EL, of a monovacancy. These include simple models involving the breaking of atomic bonds on moving atoms from the interior of a crystal to the surface, models combining elastic calculations with surface-energy terms and detailed quantum mechanical calculations. The simler models give the correct order of magnitude of &, but tend to overestimate it by a factor of about two. The quantum mechanical calculations4"7 have been carried out for the noble and alkali metals with generally reasonably good agreement with the available Ef data. The calculation of entropy of formation Sfv14 lnvolves a fundamental calculation of the perturbation of the phonon spectrum caused by the creation of a vacancy. Huntington, Shirn. and wajda8 have given an approximate evaluation of sJV by considering an Einstein model for the localized vibrations in the immediate neighborhood of the defect and then using elastic theory to calculate the entropy associated with the shear stress field in the distorted crystal (as originally proposed by Zenerg). They also included a term due to the dilation of the crystal. They obtained a value of 1.47k for copper, in good agreement with the experimental value (1.50k). However, Nardelli and Tetta- manzi1° have recently shown that neglecting the coupling between atoms (Einstein Model) may lead to a serious error so the agreement may be somewhat fortuitous. In this work simple linear elastic theory is used to calculate the entropy and energy of formation of mono-vacancies. Despite the simplicity of some of the assumptions involved, the agreement with the available experimental data is remarkable. However. the reasonable degree of success in the application of linear elastic calculations to the excess entropy of a solute atom in a dilute solid solution1&apos; indicates that the application of elastic theory to vacancies. where the interaction of different atomic species is not involved, may not be inappropriate. THE ELASTIC MODEL The metal is assumed to be a spherical elastic continuum. A small spherical cavity of volume V = 4i;v:&apos;/3 is cut from the center. removed. and dissolved rever-sibly in the bulk of the material. TO a good approximation no net atomic bonds are broken and the material does not undergo a volume change although the externally measured volume of the body would increase by V. The radius of the sphere of metal is much larger than r Next a negative pressure is applied to the cavity causing its surface to be displaced inward by an amount simulating the relaxation of the lattice around a monovacancy. In this model the energy and entropy accompanying the distortion are taken as 4, and <. As a first approximation the equation of state for the solid is taken as: r = ro(i + *~D LiJ where K is the bulk modulus. P the hydrostatic pressure. Vo the volume of the material at 0°K and zero pressure. and d+/dT = 30. where 0 is the linear thermal expansion coefficient. The variation of entropy with hydrostatic pressure is given by the Maxwell equation: These equations give the entropy change resulting from increasing the hydrostatic pressure from 0 to P as: and since • we have: This is the entropy arising from the dilation resulting

Jan 1, 1970

By M. E. Lombardi

IN comparison with the mining industry the petroleum industry is new and inexperienced, and until now it might have been called the fortunate industry. Its great good fortune consisted in two things; a bountiful supply hidden by nature in the rocks of the earth, and a steady and large increase, during the past twenty-five years, in the demand for petroleum products. It is a remarkable fact that consumption of gasoline in the United States has shown an increase every year since automobiles first became important, and even in 1930 there was a four per cent increase, in spite of the universal depression; the estimated increase if the times had been normal, was ten per cent. This industry has, therefore, not passed

Jan 1, 1931

US 4,195,426-Manganese nodules are recovered from relatively great depths on the ocean floor using a self- propelled remote-controlled vehicle having a V-shaped tubular structure with a system of crawlers at its apexes. Underneath each side of the V-shaped structure is a scraping system for gathering nodules and directing them into a tubular conveying system for elevation to the surface ship. A given area of sea bed is fully mined in a single pass of the vehicle. V. Banzoli, V. Di Tella, and P Vielmo, assigned to Tecnomare, SPA. Apr. 1, 1980. 5 pp. 137-60) Filed. 3-31-78 (892,197). Priority: Italy, 4-1-77 (84119A/77).

Jan 1, 1982

By Huntington Adams

The arrangement of a flow of cyanide-pulp through Pachuca tanks in agitation, so as to permit a continuous process, instead of alternate filling, agitation, and emptying, has been proposed by various writers within the last two years, and more particularly by A. T. Grothe, agent for the Brown patents on Pachuca tanks in Mexico. It was first put into practice, I believe, by M. H. Kuryla at the Esperanza mine in El Oro, Mexico. The starting of agitation in Pachuca tanks after filling may offer no serious difficulties with ores which do not settle rapidly in such tall tanks; and the adaptation of the tanks to continuous agitation under such conditions may give simply a somewhat more convenient method of treatment and greater agitation-capacity for a given number of tanks, because of the saving of time lost in filling and discharging. But in the treatment of pulp which tends to settle rapidly, as in the cyaniding of concentrates or of the whole pulp of ores containing heavy sulphides, the packing of the slime at the bottom may cause much trouble. The use of the radial air-pipe attachments near the top of the cone and of the air-valve outside of the air-lift tube at the bottom may obviate the difficulty to some extent; but the action of the radial air-pipes on the cone-sides is that of a sand-blast, and their continuous use cuts through the tanks. Moreover, even when these pipes are used, some pulps will pack tightly below them in the cones. Under such conditions the use of Pachuca tanks with intermittent filling and discharging becomes a troublesome process. Time is lost in starting agitation; large quantities of compressed air are wasted; pulp is blown over the tank-tops; and not infrequently it may be necessary to dig out the bottoms of tanks by hand. This trouble is the only important one occurring in the use of Pachuca tanks; and, since it is caused by intermittent filling, the arrangement of a continuous flow of pulp from tank to tank,

Jan 1, 1912

AS provided in Article VIII, Section 4 of the By- laws, the Papers and Publications Committee has formulated the following, rules of pro-cedure and submitted them to the Board of Directors for consideration and approval. In preparing these rules the committee, and an active subcommittee con-sisting of Messrs. Norris, Sharpless; Fohs and Wither-ell, have kept in mind the desirability of codifying the practice that has grown up through the now sev-eral years of experience of the committtee, without casting them in a mold so rigid as to be hampering. The problems of the Institute change from year to year and the methods of publication must change also to meet each new situation as it arises. "The estab-lishment of divisions and special volumes devoted to the papers. read before each required certain changes from former practice. These rules have been framed with this in view. The committee suggested, however, in its letter of transmittal, that the system will be made all the more workable if the Board will, as far as practicable, in making appointments to this committee, arrange for representation from each of the professional divisions and technical committees. It is understood that the chairman of the committee will be named by the Board. The rules regarding spe-cial volumes have been framed, keeping in mind the present policy of distribution, as already approved by the Directors under which the special volumes go only to the special. groups except on request. The committee has not attempted to provide rules governing consideration of any appeal made to the Board from one of its decisions, but its services and files will necessarily be at the full service of the Board in any such event. The rules which were ap-proved by the Board at its meeting on March 30, 1928, are as follows: Signed by C. S. Witherell, Chairman. (A) The authority of. the Committee on Papers and Pub-lications, hereinafter called the Committee, is defined in Art. VIII, Sec. 4 of the By-laws of the Institute, which reads as follows: "Papers and Publications: The Committee on Papers and Publications shall consist of the Secretary of the Institute, and at least twelve members of the Institute, to assist in passing on all papers offered for publication. They shall be appointed annually by the Board of Direc-tors, on recommendation of the President, and shall have authority, subject to appeal to the Board, to accept or reject papers for publication in the Transactions and Technical Publications of the Institute. The Commit-tee shall formulate a set of rules of procedure which, when approved by the Board, shall have the force of By-laws until revoked or amended." The policy of the Committee will be to uphold the ob-jects of -the Institute as set forth in the Constitution (Arti-cle 1, Sec. 2).

Jan 5, 1928

By W. Mostowitsch, H. O. Hofman

In our investigation of the Behavior of Calcium Sulphate at Elevated Temperatures with Some Fluxes,&apos; we incidentally studied the decomposition of ferric oxide when heated in a current of dry air. We found that at 1,500° C., with 15-min. periods of heating, Fe²,O³, hardly changed in weight, the greatest loss being 0.23 per cent., and we therefore concluded that the compound remained unchanged at 1,500° C. in a current of dry air. In a more recent experiment we heated Fe²,O³, in a current of dry air and found that there was a decided loss in weight. A new investigation upon the behavior of Fe², O³, using a larger amount of substance and heating for a longer period of time, revealed the fact that a measurable dissocia-

Jan 1, 1910