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THE COMMITTEE, appointed early in May, met and organized in Washington, May 9, 1923, and were then advised that such data as they required would as far as obtainable be submitted to them in tabulations, and that they could not be allowed to see the individual reports nor know the identity of the operators on whose reports the figures submitted were based, therefore the Committee's valuation is based on data received from your statisticians, and on tonnages estimated by your staff and by the United States Geological Survey. Various methods of valuation for mining properties have been suggested, but all authorities seem to agree in accepting, as the fairest and most practicable and logical, a capitalization of the estimated future earnings, when such estimate can reasonably be made. Hoover and Finlay both emphasize this. The United States Supreme Court says in Cleveland, Cincinnati, Chicago & St. Louis Railway Co., v. Backus, 154 U. S. 439: But the value of the property results from the use to which it is put and varies with the profitableness of that use, present and prospective, actual and anticipated. There is no pecuniary value outside of that which results from such use. The amount and profitable character of such use determines the value. The Committee on Federal Taxation of the American Institute of Mining and Metallurgical Engineers, appointed in 1919, in its report states: A proper value of a mining property is the present value of the prospective net earnings, taking into account probable variations in output and value. Ingalls (" Wealth and Income of the American People," p. 97) says: The fundamental principle of mine valuation is the present worth of an annual dividend accruing during the period of years corresponding with the life of the mine. It is a convention that the estimated period shall not be more than 30 years.

Jan 1, 1924

By C. E. Sims, C. A. Zapffe

AN investigation of the behavior of inclusions in steel several years ago1 led to the conclusion that some of the commonly occurring inclusions in steel have appreciable solubilities, particularly in liquid steel. In the belief that further study and clarification of this matter was warranted, a laboratory study of oxides in liquid steel was started. These oxides are generally the result of deoxidation treatment, and the basis of an understanding of their behavior must be, therefore, the behavior of the deoxidizer in liquid iron. The Fe-Si-O system was selected for the first study, and the apparatus used and experiments conducted are described herein. APPARATUS The apparatus is shown in Fig. I and the system is shown by diagram in Fig. 2. Furnace Atmosphere Commercial hydrogen (1) passes through an orifice (2) into a manometric system that measures the tankside pressure (3) and the back pressure (4) in the system. A water trap (5) guards against excess tankside pressure. A by-pass with stopcocks (6 and 7) is provided, so that the hydrogen can be routed directly from the tank to the furnace if desired. When stopcock 7 is closed and stopcock 6 is open, the gas proceeds through the conditioning train, of which the first unit is a furnace (8) that contains platinized asbestos at 350°C. The temperature is measured by a thermocouple and potentiometer (9) and is controlled by a slidewire resistance (10). In [ ] this furnace free oxygen is converted to water vapor. The exiting gas passes over a water bath (11) kept slightly below boiling temperature by an auxiliary heating unit (12). This unit also heats a surrounding copper coil (13) containing water, and the heated water rises through a collar (14)

Jan 1, 1942

By Harold L. Hinds

The Homestake Ledge or Lead was discovered by Fred and Moses Manuel on April 9, 1876. They recovered a small amount of gold from the quartz outcrop, but, unfortunately, they were prospectors not hardrock miners. Their claim was sold to a group of experienced California mining men in 1877. These mining men incorporated their holdings as the Homestake Mining Company. This was the beginning of one of the greater gold mining enterprises of the Western World. Metallurgical operations progressed over the years from an eighty- stamp grinding circuit using amalgamation for recovery to the more complex circuit of today. The Homestake Mine, today, is an underground mine with the deepest winze reaching the 8,000-foot level. The ore is hoisted to the surface by two primary shafts, the Ross Shaft and the Yates Shaft. See Figures 1 and 2. It is crushed in three-stage crushing plants located in the headframes. From here, it is trammed to the mill fine- ore bins by electric locomotives. The Lead grinding plant milling circuit, known as the South Mill, receives ore from the crushing plant at minus 112 inch (Figure 3). This material is dumped into overhead fine-ore bins from five- ton rail cars. The fine-ore bins have a live capacity of about 3,700 tons. The South Mill bins can also be fed by a conveyor system which reclaims ore from an 80,000-ton capacity stockpile. This stockpile is built up from peak mining production periods and available surface low grade material. It is then reclaimed during low mine production periods. The grinding circuit at the South Mill consists of four rod mills in open circuit followed by four ball mills in closed circuit. Three of the rod mills are 6-foot by 12-foot Marcy's. The other is

Jan 1, 1983

By K. A. Johnson, F. H. Ellinger, C. C. Land

The Pu-La alloy systenz has been studied by thertnal, tnzcrographic, and X-ray diffraction methods. It is churacterized by a liquid miscibility gap, a maximum solubility of about 20 ut. pct PM in y lanthunum and 19 at. pct PI* in 0 lanthanum, very little soluibility of lanthanum in the plulonium allotropes, and the absence of intermediate phases. THE existence of immiscible liquids in the Pu-La system has been reported by Schonfeld.1 A tentative phase diagram based on the results of thermal-analysis experiments has been constructed by Poole et a1 2 This diagram shows a liquid immiscibility loop with a monotectic at 77 at. pct La and 846°C. 7 lanthanum is shown to dissolve 20 at. pct Pu and to decompose by an inverse peritectic reaction (y La = L , + p La) at about 82 at, pct La and 833°C. The ß lanthanum solvus was not determined, but the thermal work indicated a maximum solubility of 16 at. pct Pu in ß lanthanum. The present investigation has defined the solubility limits of plutonium in y lanthanum and 0 lanthanum, and, with the exception of minor discrepancies, has verified the results of Poole et al. 1) EXPERIMENTAL The electrolytic plutonium melting stocks were better than 99.9 wt pct pure, the main impurities being 90 ppm Fe and 50 ppm W. The lanthanum melting stocks, supplied by Research Chemicals and the Cerium Metals Corp., were about 99 wt pct pure, the main impurity detected by our spectrochemical analysis being 2000 ppm Fe. The components for each alloy button (-5 g) were weighed on an analytical balance and were melted together in a conventional arc furnace. If no significant weight loss occurred during melting, the as-weighed

Jan 1, 1968

By Anthony Anable, J. V. N. Dorr

When separate treatment of sand and slime by cyanidation was the rule rather than the exception, as now, and when gravity concentration, rather than flotation, was the accepted method of dressing copper, lead, zinc and other base ores, classification was a separate step in ore treatment. Today, however, the picture is much different. The trend toward all-slime treatment in cyanidation and flotation has made fine closed-circuit grinding essential, and the mechanical classifier is of equal importance with the mill in the preparation of an ore for its treatment. Actually, a mill and classifier are a unit, a variation in either affecting the desired results. In developing this thesis—the mutual interdependence of the rotary mill and the classifier in modern fine-grinding practice—it would be well to consider first the different types of classifiers and mills in use today, their scope and limitations and the factors governing their selection. From such a basis as this a logical approach may be made to modern closed-circuit fine grinding, the evolution of multiple-stage grinding practice, the relation of the classifier to the mill and, finally, the trend to higher and higher circulating sand loads in the mill-classifier circuit. Such data as are germane to the subject will be given to support the thesis advanced. Mechanical Classifiers Theory.—Stokes' law, applicable to the uniform slow motion of a rigid sphere in a viscous fluid of infinite extent, states that the velocity of a particle settling under the influence of gravity is a function of the square of its radius: _ 2 g(ds - de)?2 v =9 S Where V = velocity of particle in cm. per see. g8, acceleration due to gravity d8, density of particle de, density of fluid ? = radius of particle S = viscosity of fluid

Jan 1, 1935

By H. A. Schwartz, Wolfram Ruff

The spheroidal form of the temper carbon nodules in malleable cast iron and of the graphite mottles of "mottled" cast iron suggests that in both all the graphite in a given mottle or nodule grew from a single center of crystallization or nucleus. $ There is, however, a distinct metallo-graphic difference between the mottle and the nodule; the area of mother metal impoverished in combined carbon by the crystallization of graphite in a mottle is practically coextensive with the ramifications of the graphite, while the impoverished zone of metal corresponding to a given nodule is always larger, and usually much larger, than the approximately spherical mass of graphite crystals forming the nodules. Furthermore, the mottle probably is formed during freezing and the nodule almost always at a considerably lower temperature. Assuming that the nodules or mottles can be used as a measure of the existing nuclei (capable of germination) we propose to record certain observations as to the graphitizing reaction in the light of the number and habits of growth of these nuclei. The present authors, in cooperation with others'-', have reported upon various cognate aspects of the problem. The fact that temper carbon is a mass of flakes and not a solid granule has become well recognized since the introduction of an improved polishing technique8, 9, 10 for cast iron. The problem of deriving from the circular planar intercepts of a mass of spheres of varying sizes their number and size distribution in space has also been satisfactorily solved12, 13 Growth of Nuclei in White Cast Iron It has already been shown1, 3 that the progress of graphitization with time is usual1y consistent with the assumption that nodules grow in size

Jan 1, 1936

By Wolfram Ruff, H. A. Schwartz

The spheroidal form of the temper carbon nodules in malleable cast iron and of the graphite mottles of "mottled" cast iron suggests that in both all the graphite in a given mottle or nodule grew from a single center of crystallization or nucleus. $ There is, however, a distinct metallo-graphic difference between the mottle and the nodule; the area of mother metal impoverished in combined carbon by the crystallization of graphite in a mottle is practically coextensive with the ramifications of the graphite, while the impoverished zone of metal corresponding to a given nodule is always larger, and usually much larger, than the approximately spherical mass of graphite crystals forming the nodules. Furthermore, the mottle probably is formed during freezing and the nodule almost always at a considerably lower temperature. Assuming that the nodules or mottles can be used as a measure of the existing nuclei (capable of germination) we propose to record certain observations as to the graphitizing reaction in the light of the number and habits of growth of these nuclei. The present authors, in cooperation with others'-', have reported upon various cognate aspects of the problem. The fact that temper carbon is a mass of flakes and not a solid granule has become well recognized since the introduction of an improved polishing technique8, 9, 10 for cast iron. The problem of deriving from the circular planar intercepts of a mass of spheres of varying sizes their number and size distribution in space has also been satisfactorily solved12, 13 Growth of Nuclei in White Cast Iron It has already been shown1, 3 that the progress of graphitization with time is usual1y consistent with the assumption that nodules grow in size

Jan 1, 1936

By Alexandre Pourcel

The phenomena of liquation in steel or iron ingots of all sizes, but naturally to greatest extent in the heaviest ingots, have been noticed ever since the commencement on a large scale of the Besse mer and open-hearth manufactures; but they have been studied with care during the last few years only. The English and the Ameri cans were the first to publish the results of investigation upon phe nomena of this clam, to which they have given the name of segregation. Historical. Passing by that which has been written concerning the segregation observed in gray pig-iron, of which instances were given by Karsten, we shall confine ourselves here to that which is known of this subject with exclusive reference to ingot steel and iron. Mr. H. M. Howe, of Boston, in his Metallurgy of Steel, the most complete and well-arranged treatise upon steel, gives a resume of observations, with the results of numerous analyses, bearing upon the phenomena of segregation. According to Tchernoff (with whom we discussed this question at length in 1878, in connection with the cast-steel plates of large dimensions designed for the Italian fleet, which we showed him at Terre-Noire), Kalakoutsky called attention in 1866 to the lack of homogeneity in Bessemer ingots, especially when cast in sand. Our own attention had been called to the phenomena of liquation in 1868 by a somewhat surprising fact which appeared in almost every one of a number of steel-rail ingots coming from the works of Messrs. Pierre and Emile Martin at Sireuil, to be rolled at TerreNoire. In the heating or in the first groove of the rolls, a slice of from 6 to 10 centimeters (2.4 to 3.9 inches) separated itself from the head of each ingot. As a general consequence, the section of

Jan 1, 1894

The following table summarizes the information on the Hurghada field. which is still the major producing field in Egypt. Age of field to end of 1937. years..................... 24 Producing area for gas and oil. acres.................. 1.050 Babbels Total oil production to end of 1937................... 30.188.500 Total oil production during 1936..................... 1.219.406 Total oil production during 1937..................... 1.141.230 Average oil production per acre to end of 1937.......... 28.750 Average oil production per acre-foot to end of 1937.... 2.359 Daily average production (Nov. 1937)................ 3.162 Daily average production per well (Nov. 1937)........ 41.88 MillionB Cu. Ft. Total gas production (Aug. 1925 to end of 1937)....... 4,189 Total gas production during 1936.................... 281 Total gas production during 1937.................... 222.5 Maximum daily average in 1937 (July)............... 0.7 Number of producing wells completed to end of 1937... 97 Number of producing wells completed during 1937..... 3 Number of wells abandoned during 1937.............. 1 Producing wells at end of 1937....................... 78= Total number abandoned wella at end of 1937......... 19 Total number dry wells at end of 1937................ 20 Average depth of bottom of producing horizon, ft...... 1,720 Average depth of top of producing horizon, ft.......... 1,598 Character of oil, approximate average in 1937: gravity at 60" F., 0.900; base, mixed. Character of gas, approximate average during 1937: gallons gasoline per 1,000 cu. ft., 6.9. Producing rock (main): Nubian (?) sandstone. Cretaceous (?); character, sand rock and sandstone. 1 Figures were given in E. tons. A conversion factor of 6.98, based on 0.900 sp. gr., was used to obtain the number of barrels.—Ed. *All pumping.

Jan 1, 1938

By Gerhard Derge

THE introductory paper1 of this series described the potential behavior of tin in sodium carbonate and bicarbonate solutions whose pH ranged from 8.4 to 11.2 and demonstrated that significant and reproducible results could be obtained by proper attention to experimental technique. In examining the corrosion of tin under such conditions, it is desirable to know the effects of anions, aside from carbonate, that are likely to be present in commercial materials packaged in tin. Therefore, in this paper the potential behavior of tin in carbonate solutions to which sodium fluoride, chloride, bromide, iodide, sulphate, nitrate, monobasic phos-phate, dichromate, perborate and acetate have been added will be described. For most of the additions, solutions containing 0.001 and 0.01 .moles of the added material were studied. The experimental procedure was exactly the same as that described in the first paper; the pH of the electrolyte was controlled by adjusting the ratio of carbonate to bicar-bonate as follows: pH 0.1 M NaHCO3 8.4 2 parts 0.1 M NaHCO3, 1 part 0.1 M Na2CO3 9.5 1 part 0.1 M NaHCO3, 2 parts 0.1 M Na2CO3 10.0 0.1 M Na2CO3 11.2 The reagents used were all of C.P. grade. The anions studied may be divided into three groups: (1) anions that had little or no effect upon the potential curves-sulphate, nitrate, and acetate; (2) those that helped to prevent corrosion at low pH only-fluoride, chloride, bromide, and iodide; (3) those that helped to prevent corrosion at high pH also-phosphate, perborate, and chromate.

Jan 1, 1939

By James H. Pannell, John Dasher, Wilfred L. Freyberger, A. M. Gaudin

A new sorting process for beryllium minerals is described. This depends upon emission of neutrons upon irradiation by gamma rays, a nuclear reaction which is specific for beryllium at the appropriate energy level. Signals given by neutrons when ore passes on a belt are changed to mechanical commands through amplifiers and other electrical equipment.

Jan 4, 1950

By E. B. Burwell, R. H. Nesbitt

A NEW milestone in the progress of photography and subsurface exploration was reached when the Chief of Army Engineers announced the development of the NX borehole camera. In obtaining continuous undistorted cylindrical color pictures of dry or water-filled borings the device surpasses all other cameras designed for photographing interior surfaces of pipes, wells, and conduits. The usefulness of the camera and the unique projector that comes with it are at once apparent. To the geological, mining, and civil engineer alike it signifies the end of guesswork with respect to underground conditions that have eluded identification by conventional core-drilling methods. To the medical profession it may well signal new progress in photo optics which could result in cylindrical color photographs supplementing the X-ray and existing photographic methods used in exploratory surgery.

Jan 8, 1954

An informal meeting of the Conferees of the Development Committees of the four Societies was held in New York on July 2, 1919, at which the scope of the work was considered, and a sub-committee oil Procedure, consisting of the chairmen of the Conferees from each of the four Societies, was appointed to arrange the program for and the time and place of the first formal meeting. The Conference subsequently adopted the name, " The Joint Conference Committee." The Joint Conference Committee convened at the Hotel Montclair, Montclair, N. J., Aug. 13, 14, and 15, and in New York, Sept. 15, 16, and 17, 1919. The Committee has divided its report into two parts, that covering the public activities and that covering the society activities of common interest to the four societies.

Jan 12, 1919

By Persifor Frazer

TILE ore property of Mr. Augustus Roop is situated about one and a half miles south of the New Windsor Station of the Western Maryland Railroad and is connected with the town of New Windsor by the Liberty and New Windsor Turnpike. It is about forty miles distant from Baltimore, and about seven miles west from the county town of Westminster, and a little more northeast from the celebrated Liberty Copper Mines. (See accompanying Maps 1 and 2.) The property comprises about 140 acres, lying principally

Jan 1, 1881

By L. C. Brown, A. J. Stewart

Phase transformations have been studied in Ag-Zn alloys quenched from the high-temperature bcc 0 phase and lying in the composition range 37.4 to 50.0 at. pct Zn. On quenching, the alloy with the lowest zinc content transformed to massive a (fcc); all other alloys formed the ordered (3' phase. On deformation, a martensitic reaction took place forming a close-packed structure. At Lou' zinc contents transformation to this structure was complete. However, above 43 at. pct Zn a p.rogressively increasing amount of ß' was retained following deformation. The close-packed structure was fcc at lower zinc contents (under 47 at. pct Zn) and either hcp or a mixture of fcc and hcp at high zinc concentrations. The structures produced by cold working were unstable and on aging transformed to the ß' phase or the complex hexagonal to phase. For low zinc contents (under 43 at. pct) the fcc st-ructure transformed directly to the equilibrium To phase. With higher zinc contents, some 13' was retained following defownation, and on aging the amount of this phase relative to the close-packed structure increased. On further aging both structures transformed cornpletely to PO. Metallographic examination indicated that the nature of the deformation product depended very markedly on the mode of deformation. Tensile deformation gave a microstructure characteristic of thermal martensite. KING and Massalski1 have shown that an alloy of Ag-50 at. pct Zn quenched from the high-temperature bcc ß phase undergoes a low-temperature ordering reaction forming ß' which can be retained to room temperature. On deformation an hcp phase is produced, although this is unstable and the structure reverts completely to ß' on aging. In the present paper, the work of King and Massalski is extended to cover a wide composition range in the p phase, observations being made of the structure of the quenched 13 and of the effects of deformation and aging. The relevant portion of the Ag-Zn phase diagram is shown in Fig. 1. King and Massalski have shown that close to stoichiometry the ß' phase is the equilibrium structure at low temperatures. The approximate composition range of this phase, taken from a recent paper by Pops and Massalski,3 is shown on the phase diagram. The locations of atom sites are very similar in the ß' and to structures, and the 4, structure can be derived from the 0' structure by a small movement of atoms mainly in the direction of the cube diagonal.4'5 However, the probability of filling any particular atom site by a silver or a zinc atom is markedly different in the two structures. The structure can be considered partly ordered but the arrangement of the ordered atoms is completely different from that in the p' structure and transformation from ß' to requires a large fraction of the atoms to change position. It has been shown that the ß' transformation is thermally activated involving normal nucleation and growth processes.5,8 Massalski and Barrett7 have shown that in the Cu-Zn binary the (3 phase can be retained in the ordered state to room temperature over a wide composition range. On deformation a new close-packed phase is produced, the structure varying from fcc to a mixture of fcc + hcp to hcp alone with increasing zinc concentration. It appears that an ordering reaction is necessary to retain the bcc phase to room temperature. In CU-Ga,8 the bcc phase cannot be retained to low temperatures as it transforms by a massive reaction above the ordering temperature of the ß phase. The structure of the massive phase is very similar to that in Cu-Zn, varying from fcc to fcc + hcp to hcp with increasing zinc concentration. Similar structures have also been observed in CU-A1,9 Ag-Cd,10,11 and Ag-Al.12 EXPERIMENTAL The alloys were prepared by melting fine silver (99.99 pct purity) and electrolytic zinc (99.999 pct

Jan 1, 1969

By Francis H. Brownell

During the 1920's lead consumption in the United States reached the highest average total ever known. For the ten-year period 1921-'30, it was slightly over 600,000 tons per year, or say 50,000 tons per month, and the price averaged 6.81 per lb. But the I930's witnessed a severe drop in the consumption of lead is in other business activities. The average U.S. consumption for the ten-year period 1930-'40 was slightly less than 380,000 tons per year, or under 32,000 per month, with the average price dropping to 1.191c. per lb. The outlook in early 1939 was for a continuation of this average consumption and price a demand of 35,000 to 40,000 tons per month, and a price level of 4 1/2 to 5c. in the United States.

Jan 1, 1941

By M. van Swaay, C. E. Birchenall

A. S. lBrling (Johnson, Matthey & Co. Ltd., Laboratories)— Because of its initial emphasis upon the production of membranes by powder metallurgy and by normal casting and rolling techniques, this paper is of considerable interest to those concerned with the design and application of industrial diffusion units. As the subsequent performances of the three grades of palladium were not compared in detail, it can perhaps be concluded that specific permeabilities were very similar. A short table in which the absolute diffusion rates obtained by the Authors with their three grades of palladium were compared with those of other investigators18-25 would, however, have been of particular value in view of the very variable results obtained with this membrane material. The Authors state early in the paper that the permeability of the thoriated samples decreased in much the same way as that of the nonthoriated samples. Later, they emphasize that sintered palladium without thoria was very susceptible to poisoning and did not respond as well as the other materials to the decontamination treatment. These results, which suggest that sintered membranes are less effective than those produced by normal methods, have considerable industrial implications, and amplified experimental details would be very welcome. The results of the Authors differ in one important respect from those of other investigators. Thus, no "bleeding" was required to maintain a constant rate of diffusion, although Davis, Darling, and De Rosset found this to be necessary. Davisz3 found that "bleeding" was necessary even when the hydrogen had already been purified by diffusion through a palladium tube, and it would be of value to know the purity of the gas stream emerging from the purification train shown on Fig. 1 of the Authors' paper. The Authors show that diffusion rates varied according to the square root of the pressure difference providing that the palladium membrane was not contaminated in any way. This finding is in agreement with the results of those workers2,18,19,23,24 who diffused their hydrogen through the membrane into a partly or completely evacuated system.Those workers who did not find this square-root law dependence did not have a partial vacuum on the downstream-side of the membrane.'' The difference between the two experimental con- ditions appears to be significant, as the absolute diffusion rates per sq cm of diffusion area are lower when the square-root law dependence is not observed. While the effect could be attributable to poisoning of the membrane it is conceivable that a positive pressure on the downstream side of the membrane might influence the mechanism of diffusion. In view of the capricious behavior of palladium, factors of this type, which are likely to influence its industrial significance, should be carefully considered. M. van Swaay and C. E. Birchenall (authors' 9-eply) — Our Eq. 191 may be compared with several others for hydrogen diffusion in palladium: D = 5.95 x exp (-5770/1)' D = 3.55 x 10"3 exp (-5550/)' D = 4.3 x 10"3 exp (-5620/1')' Other values are given in the literature, but in many cases surface poisoning may have affected the results. No analysis was performed on the hydrogen gas stream after purification. It should be noted that the presence of liquid nitrogen traps near the heated membranes may have set up convection currents and provided the equivalent of "bleeding." The question of whether a partial vacuum existed on the downstream side of the membrane is not clear. Does it imply that there is something unique about the permeability measured near one atmosphere pressure? We do not believe that there is. When square root pressure dependence is not observed, diffusion rates are not measured. Is "absolute diffusion rate per sq. cm. of diffusion area" equivalent to permeability? The terminology is new to us. In any case we doubt very much that pressures of the order of several atmospheres can affect the mechanism of diffusion.

Jan 1, 1962

Meeting of Apr. 23, 1915.-The Iron and Steel Committee was authorized in its discretion to defer the date of acceptance of papers for the Hadfield Research Prize to Nov. 1, 1916. The sum of $250 was appropriated as a guarantee fund to establish a Library Research Bureau in co-operation with the other Founder Societies. The sum of $50 was appropriated to the Puget Sound Section. The sum of $250 was appropriated to the San Francisco Section. The sum of $125 was appropriated to the St. Louis Section. The matter of memorializing the New York State Constitutional Convention was referred to the New York Section of the Institute with authority to act as a Section only. Upon recommendation of the Committee on Membership, 50 Mem¬bers, 1 Associate, and 6 Junior Members were elected.

Jan 6, 1915

By R. L. Watts

Successful mining of taconite has required the solution of a series of difficult problems, including more efficient magnetic separation. Progress in this field is evidenced by reductions in operating and capital costs made possible by the advances in permanent magnetic materials and in new circuits for better utilization of these materials. The advent of the flux control circuit appears to be one of the more important breakthroughs in permanent magnet drum design circuitry and has contributed greatly to the economics and metallurgical requirements of the modern day taconite concentrators. High strength permanent magnetic separators are now replacing electro types in many applications requiring field strengths of 900 - 1000 gauss measured at 2 in. This is made possible by the new circuits having gauss readings at 2 in. previously attained only by electromagnets.

Jan 12, 1967

New York Holds monthly meetings, except June, July and August JOHN A CHURCH, JR, Chairman JOSEPH E POGUE, Vice-chairman SIDNEY ROLLF, Vice-chairman EDWARD C MEAGHER Secretary, Texas Gulf Sulphur Co, 41 E 42nd St, New York M H MERRISS, Treasurer, 42 Broadway, New York ARTHUR NOTMAN T T READ Boston Meets first Monday of each winter month EDWARD C GEITHER, Chairman WILLIAMS BLACK, Vice-chairman DONALD H MCLAUGHLIN, Secretary-treasurer, Rotch Bldg, Harvard Univ, Cambridge, Mass J L GILLSON A G WAITD

Jan 1, 1923