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By John D. Meahin

THE use of digital methods for generating crystallo-graphic data is well-established and many programs are now available. Transmission electron microscopy usually requires a knowledge of the electron diffraction pattern which is obtained by plotting a planar section through reciprocal space. With cubic symmetry these sections are very easily produced, but with hexagonal and lower symmetry systems considerably more labor is involved. Johari and Buchanan1 have written a Fortran program for generating standard projections and along similar lines we have produced a short but completely general program for generating any section through reciprocal space. The required inputs are the lattice parameters and angles for the real crystal. The Miller indices of the direction [U, V, W] parallel to the electron beam are then specified and the program will generate the Miller indices of the plane normals perpendicular to [U, V,, W] up to some specified integer. A subroutine can be inserted to test for forbidden reflections if desired. We have used such routines for fct and hcp crystals. As each permitted index is generated it is printed or punched out and no storage arrays are utilized in the computer. The normal diffraction pattern corresponds to the zero-order Laue zone, but with thin crystals or crystals of large lattice parameters the higher-order Laue zones may contribute to the diffraction pattern. Accordingly the program will generate successive Laue zones and project them onto the zero-order zone. The output of the program first lists the zone axis [C, V, W] and the Laue zone, and then gives a list of permitted reflections and the corresponding XP and YP coordinates of the reciprocal lattice point in angstroms-'. In addition, ZP, the perpendicular distance of the reciprocal lattice point from the (U, V, Ur) plane in reciprocal space is given, as is the reciprocal interplanar spacing. In the case of the zero-order Laue zone ZP is zero. A diffraction spot from the higher-order Laue zones will be very slightly displaced from the computed coordinates as its position in an actual pattern is given by projection along the diffracted beam2 and not along [u, V, w]. For any given electron wavelength this correction could be readily incorporated into the program, but as it only amounts to -1 pct it was decided to leave the program in its most general form, i.e ., a computation of points

Jan 1, 1970

The accompanying sketch shows the interesting position of Salt Lake City with reference to Western mining areas and justifies its title "The Center of Western Mining." In the last twenty years, the area embraced within a circle of 600 miles radius with Salt Lake City as its center has produced 79.87% of the gold, 91.9% of the Silver, 77.47% of the copper, 53.61% of the lead and 26.55% of the zinc produced in the United States, including Alaska. This area also contains the greatest coal deposits of the continent, some of the greatest oil deposits, great iron deposits and many other important mineral resources. The 600-mile circle contained 69% of the active operators of other than coal mines and 40% of the men employed in mines other than coal mines of the United States, including Alaska, for the four-year period ended with 1923.

Jan 1, 1925

The Industrial Minerals Division met jointly with the Materials and Equipment Division of the American Ceramic Society at State College, Pa, Sept 24-26 Headquarters were at the Nittany Lion Inn Thurs- day afternoon was devoted to a tour of inspection of the Bell Mine, American Lime and Stone Co , Bellefonte, Pa The party returned to State College for dinner and in the evening the Division's executive committee held a brief session There were four technical sessions Friday morning, Mining, afternoon, Beneficiation, Saturday morning, Industrial Minerals and Beneficiation There was an informal banquet at the Nittany Lion Inn Friday night with 93 present Edward Steidle was toastmaster Brief talks were made by President F C Flint and Secretary Ross Purdy, of the American Ceramic Society, Oliver Bowles, Chairman, Industrial Minerals Division, Adrian Morse, assistant to the president, Pennsylvania State College, and George Otis Smith, past president A I R'I E

Jan 1, 1937

On Sept. 22 to 26, the Institute will hold its 120th meeting in Chicago. The program arranged provides for technical sessions on: Mine Taxation, Non-ferrous Metallography, Coal and Gas, Milling, Oil, Industrial Organization, Geology, Non-ferrous Metallurgy, Mining and Local Resources, Iron and Steel, Symposium on Sulfur Coals, Symposium on Pyrometry. Inspection trips have been arranged to: Gary Steel Plant. La Salle District: Zinc smelters, coal mines, cement works, America's first permanganate plant, many varied industries, scenic trips. North Chicago and Milwaukee: Mining-machinery manufacturing plants, tungsten and molybdenum reduction plants. East Chicago and Whiting: Lead refinery, oil refinery. Franklin and McCoupin: Coal fields. Chicago: Nearly every kind of metallurgical and manufacturing industry. MONDAY, SEPT. 22d Morning Registration, Non-ferrous Metallurgy, Coal and Gas. Afternoon Coal and Gas Milling Industrial Geology, etc. Evening Smoker. TUESDAY Morning Gary. Afternoon Gary. Iron and Steel. Evening Oil, Iron and Steel.

Jan 9, 1919

By George D. Dub

Owens Lake is at present a source of important nonmetallic minerals, sodium carbonate (soda ash, Na2CO3); sodium sesquicarbonate (trona, Na2CO3.NaHCO3.-2H2O) and borax, (Na2B4O7.10H2O). Owens Lake is a closed basin in the southern part of Inyo County, California, at the southern end of Owens Valley, east of the Sierra Nevada Mountains and west of the Coso and Inyo Mountains. Broadly considered, it is in the Great Basin area, but at no time was it a part of Lake Lahontan. Closed Basins Closed basins are phenomena of arid or semiarid regions where outflow is considerably less than inflow and where accordingly soluble salts concentrate in residual liquid. When inflowing waters originate in areas where the rocks are predominantly marine sediments, the residual basin liquid is primarily a chloride, brine; if the rocks are largely igneous, the residual brine tends to be alkaline containing carbonates, and sometimes borates as well. Since normally, both types of rocks occur in regions contiguous to closed basins, residual liquids do not often fit into the two broad divisions mentioned. No two residual brines are exactly alike, just as no two ore deposits are exactly alike. Even out of the same closed basin, it is possible to get widely different analyses of liquids since underground and surface flows, as well as local evaporation rates and other conditions might have a marked influence on residual-liquid compositions. At Searles Lake, The American Potash and Chemical Corporation is building a plant to process a lower-level brine which is considerably higher in sodium carbonate and borax, and lower in potassium chloride, than that company has processed for many years. F. W. Clarke1 has classified waters of closed basins as follows: I. Chloride type; largely sodium chloride (NaC1) and of oceanic type, such as Great Salt Lake. Related is -the Dead Sea, a bittern residue of magnesium, potassium and sodium chlorides. a. Sulphate type; largely sodium sulphate (Na2SO4) with considerable sodium chloride such as Sevier Lake, Utah; Laramie Lakes, Wyoming; Dale Lake, California. 3. Carbonate type; high in carbonates and fairly high in sulphates, such as Moses Lake, Eastern Washington; and the Nebraska Potash Lakes. 4. Carbonate—chloride type; lower in carbonates than type 3 and about equally rich in sulphates, such as Pyramid Lake, Nevada. 5. Sulphate—Carbonate type; quite high in sulphates and carbonates, such as Pelican Lake, Oregon. 6. Triple type; considerable quantities of carbonates, sulphates and chlorides

Jan 1, 1948

By George D. Dub

Owens Lake is at present a source of important nonmetallic minerals, sodium carbonate (soda ash, Na2CO3); sodium sesquicarbonate (trona, Na2CO3.NaHCO3.-2H2O) and borax, (Na2B4O7.10H2O). Owens Lake is a closed basin in the southern part of Inyo County, California, at the southern end of Owens Valley, east of the Sierra Nevada Mountains and west of the Coso and Inyo Mountains. Broadly considered, it is in the Great Basin area, but at no time was it a part of Lake Lahontan. Closed Basins Closed basins are phenomena of arid or semiarid regions where outflow is considerably less than inflow and where accordingly soluble salts concentrate in residual liquid. When inflowing waters originate in areas where the rocks are predominantly marine sediments, the residual basin liquid is primarily a chloride, brine; if the rocks are largely igneous, the residual brine tends to be alkaline containing carbonates, and sometimes borates as well. Since normally, both types of rocks occur in regions contiguous to closed basins, residual liquids do not often fit into the two broad divisions mentioned. No two residual brines are exactly alike, just as no two ore deposits are exactly alike. Even out of the same closed basin, it is possible to get widely different analyses of liquids since underground and surface flows, as well as local evaporation rates and other conditions might have a marked influence on residual-liquid compositions. At Searles Lake, The American Potash and Chemical Corporation is building a plant to process a lower-level brine which is considerably higher in sodium carbonate and borax, and lower in potassium chloride, than that company has processed for many years. F. W. Clarke1 has classified waters of closed basins as follows: I. Chloride type; largely sodium chloride (NaC1) and of oceanic type, such as Great Salt Lake. Related is -the Dead Sea, a bittern residue of magnesium, potassium and sodium chlorides. a. Sulphate type; largely sodium sulphate (Na2SO4) with considerable sodium chloride such as Sevier Lake, Utah; Laramie Lakes, Wyoming; Dale Lake, California. 3. Carbonate type; high in carbonates and fairly high in sulphates, such as Moses Lake, Eastern Washington; and the Nebraska Potash Lakes. 4. Carbonate—chloride type; lower in carbonates than type 3 and about equally rich in sulphates, such as Pyramid Lake, Nevada. 5. Sulphate—Carbonate type; quite high in sulphates and carbonates, such as Pelican Lake, Oregon. 6. Triple type; considerable quantities of carbonates, sulphates and chlorides

Jan 1, 1948

By F. H. Ellinger

TI HE crystal structure of neodymium has been re-A ported by Quill1 and by Klemm and Bommer"s to be hexagonal-close-packed, Strukturbericht-type A3, with a, = 3.650.4, c, = 5.890.4, c/a = 1.614. Klemm and Bommer,% owever, pointed out that the observed intensities of the lines of the neodymium powder pattern agreed only in part with the intensities calculated for the type A3 structure, and that the neodymium powder pattern showed extra lines which could not be traced to impurities. They found that these extra lines could be accounted for by doubling the c-axis, but apparently they did not consider their evidence to be sufficiently conclusive to justify reporting the doubled c-axis. In the present work, the structure of neodymium was found to be double hexagonal-close-packed. The neodymium metal used in the present investigation was obtained through the courtesy of F. H. Spedding of the Ames Laboratory. Its major impurity was stated to be 0.03 pct Ca. The author's spectrographic analysis indicated high purity and carbon was determined to be less than 30 ppm. X-ray powder specimens were prepared from filings stress relieved in vacuum at 200°C for 50 hr. Powder photographs were taken in an 114.6 mm diam camera (Straumanis film mounting) at room temperature and in a 19 cm diam Unicam high temperature camera at elevated temperatures. Copper x-radia-tion was used for all the photographs. The powder pattern of neodymium was found to index to a hexagonal unit cell with dimensions, as determined from the high angle Ka doublets, of: a.= 3.655+0.001.4; c, = 11.796+0.004.4; and c/a = 3.227 at room temperature. The measured density of neodymium shows that this cell contains 4 atoms, the calculated density is accordingly D, = 7.02 g per cu cm. The diffraction data for the first 15 lines of the powder pattern are listed in Table I. In a double hexagonal-close-packed unit cell, the 4 atoms would be in the positions (0,0,0), (0,0,%), (1/3, 2/3, 1/4), and (2/3,1/3,%) of space group P 6,/mmc. On the basis of these positions, the relative intensities of the reflections were calculated using the expression: 1+cos2 20 I oc \Frp 1 ' sin2 0 cos 0 where F is the structure factor and p is the multi- plicity factor. Since absorption was not taken into consideration, comparison of observed and calculated intensities should be made only for neighboring reflections. Each atom has 12 neighbors, 6 in the basal plane at a distance of 3.655.4 and 3 above and 3 below at the closer distance of 3.626.4. These distances correspond to an average radius of the neodymium atom of 1.820.4. The description of this structure in terms of A, B, and C close-packed layers of atoms is ABAC ABAC. ...... The structure repeats every fourth layer and the stacking sequence of the second, third, and fourth layers corresponds to cubic-close-packing of atoms. A series of powder photographs taken at successively increasing temperatures up to 680a10"C revealed that the double hexagonal-close-packed structure is stable up to this temperature. Acknowledgments The authw wishes to thank W. H. Zachariasen and A. S. Coffinberry for their helpful comments on this work and also Marion Gibbs for measuring the diffraction films. This work was sponsored by the United States Atomic Energy Commission.

Jan 1, 1956

ROBERT F. MEHL, Chairman ALBERT J. PHILLIPS, Past-chairman ROBERT H. LEACH, Vice-chairman E. M. WISE, Vice-chairman W. M. CORSE, Treasurer - Louis JORDAN. Secretary 29 West 39th St., New York, N. Y.

Jan 1, 1938

By J. P. Kerr, W. N. Logan

Lack of reliable and detailed information on many of the older fields in Indiana has necessitated the use of x and y in many instances. Even in the younger fields many data were lacking. It was thought that even though much was to be desired regarding the amount and accuracy of the information on the old Trenton field, it was too important to be left out. We trust that we are not perpetuating any of the inaccuracies that are to be found in the data for Indiana.

Jan 1, 1935

President Howe : It is not so clear to me that the facts which Dr. Waldo brings forward really argue that the nature of the combination between copper and aluminum differs from that of the combination between copper and zinc or copper and tin. As regards electric conductivity, I suppose that the fact, which he thinks points to a special intimate kind of union between aluminum and copper, is that the line in his Fig. 1 is neither straight nor uniformly curved, but that its curvature varies rapidly, not to say abruptly. But we find just such variation in like curves for the copper-zinc and copper-tin alloys. Thus, a slight addition of zinc or tin to copper causes a change in color wholly out of proportion to the quantity added; and, as we add zinc or tin to copper, the tenacity rises very greatly, only to fall off abruptly with further additions of either of these metals. Dr. Waldo : My curve related only to electrical conductivity. The President : If irregularity in one physical property argues

Jan 1, 1895

On June 1, the offices of the Engineering Division of the National Research Council were moved from Washington to the sixteenth floor of the Engineering Societies Building, 29 W. 39th St., New York City.

Jan 7, 1919

[*E. O'C. Acker '86 Jinzoc Adachl '88 T. H. Aldrich '96 *Truman H. Aldrich '78 Walter H. Aldridge '89 *Anson W. Allen '87 John H. Allen '84 *Thomas Andrews '94 *William R. Analeby '90]

Jan 1, 1946

By J. T. Lapsley, I. I. Cornet, A. E. Flanigan, R. Hultgren, J. E. Dorn

With the greatly expanding use of magnesium during the war, it appeared necessary to the War Metallurgy Committee that procedures of heat treating common magnesium casting alloys be investigated systematically. Accordingly, the National Defense Research Committee of the Office of Scientific Research and Development placed a research contract with the University of California, supervised by the War Metallurgy Committee. Research on the solution heat treatment and aging of magnesium alloy AZg2, (formerly ASTM No. 17; also known as Dowmetal C or AM26o) which was done under "Restricted" Project NRC-2I, in 1942-1943, and reported in detail in a final report to the OSRD on September 3, 1943, is the basis of this paper, which has been released for publication by the OSRD. American experience with magnesium alloys prior to World War II was limited, although some of these alloys had been in commercial use since 1909. Requirements of the aircraft industry for light alloys made it imperative to understand and utilize the advantageous strength-weight properties of magnesium castings. Magnesium casting alloys are commonly solution heat- treated to increase their ultimate tensile strength and ductility; this treatment may be followed by an age hardening at elevated temperatures, which raises the tensile yield strength but diminishes the ductility. In the present investigation, AZp was studied to determine the effects on properties of various solution heat treatment and aging schedules. The principles of heat treatment of magnesium alloys are the same as for other non-ferrous alloys. The alloy studied, AZp, has a nominal composition of 9 pct aluminum, 2 pct zinc, and minor constituents. Fig I shows, by the projection of isothermal sections on the concentration plane, the solubility surface1 of the ternary magnesium-rich solid solutions as determined by X ray 'analysis. From this figure it may be seen that above approximately 375°C (707OF), AZp alloy is a single phase alloy at equilibrium; below this temperature the equilibrium condition is a two phase alloy. The beta constituent which precipitates from the solid solution exerts a hardening effect. Because the zinc concentration is only 2 pct, ancl because of its solubility relations, AZqz resembles a binary alloy of magnesium with aluminum. The solubility curve1 of Fig 2 shows how rapidly the solubility of the beta phase decreases with decreasing temperatures. Unlike many aluminum alloys, magnesium alloys do not age harden at room temperatures; precipitation hardening of AZ² alloy is performed at about 177°C (350°F). At this temperature about 3 pct aluminum

Jan 1, 1949

By L. G. Austin

If S (x) is the specific rate of breakage of size x and B (x, y) (see Table 1 for Nomenclature) is the cumulative breakage distribution function, the Herbst Fuerstenau2 assumption is that Inserting this assumption into first-order grinding equations it has been shown" that there are then simple analytical solutions to the grinding equations, as shown in Table 2. In this context "plug flow" is defined as all material passing through the mill in the same length of time, the residence time t. The term "n fully-mixed" means that the mill has a residence time distribution" which can be treated as if the mill were n equal fully mixed sections in series. In addition it has been shown that the assumption of Eq. 1 also leads to simple analytical solutions for closed-circuit, steady-state grinding with an ideal classifier at the mill exit returning oversize to the mill feed. The solutions are also given in Table 2, with µ as the ideal classifier cut size, C the circulation ratio, and Q (x) the size distribution of the circuit product. The specific surface area of these size distributions is where the density-shape factor k. is assumed to be constant with size. In practice, most methods of size analysis or area [ ] measurement have a finite lower limit, so that the integration is really performed from xm, to xm, For a realistic degree of grinding the value of So is dominated by the fine sizes because of the 1/x factor. Consider batch grinding of a feed of size y to y + dy. The batch grinding solution given in Table 2 is then [ ] The fresh surface area produced is the area of the fines plus the area of the original material remaining minus the area of the original material, [ ] Little error is introduced by neglecting the last term on the right-hand side since at t = 0 it is zero, and when t is significant the first term dominates because of the fine sizes produced. In addition, the form of P (x, t) for [ ] realistic values of S (x) 2t ax° is such that the major fraction of fresh surface produced is contained within the bottom 10% of weight of broken material, that is, for sizes for which P(x, t) < 0.1 (providing y is not near x.,). Thus for surface area purposes Eq. 3 can be approximated by [ ] becomes providing again that the feed sizes are coarse relative to xmi. Then the fresh area production is and W is the mass in the mill. The rate of surface production is WK, and the specific surface is Kt. From Table 2, the specific energy is mt/W so surface production per unit energy is [ ] Surface produced per unit energy input = KW/m (8) where m is the energy input of the mill. Clearly, identical reasoning applies to open-cycle, plug-flow grinding, with t replacing t, and Eq. 8 is obtained again. Considering open-cycle, fully mixed grinding, similar reasoning gives P(x) - t S(x) for surface area purposes, and

Jan 1, 1974

By Edward Judd

CANADA&apos;S mining industry is rapidly recovering from the depression through which it passed in 1921. Its total output of $183,029,600 in 1922 was 6.4 per cent. greater than that of 1921, and was exceeded by only three previous years, 1917, 1918, and 1920. Table 1 compares the output of a few of &apos;the more important items selected from preliminary data published&apos; by the Dominion Bureau of Statistics. TABLE 1.-OUTPUT OF CERTAIN MINERAL PRODUCTS IN CANADA PER CENT. 1921 1922 CHANGE Cobalt, metal and in compounds, lb 252,000 443,800 +76.1; Copper contents of blister, matte, and exported ores, lb 47,620,820 43,321,400 - 9.0 Refined copper, lb 4,286,000 730,000 -83.0 Gold, fine oz 926,329 1,230,985 +32.8 Pig iron, sh. tons 665,676 429,024 -35.5 Lead, sh. tons 33,340 47,085 +41.2 Nickel contents of matte, etc., lb. 19,293,060 17,496,490 - 9.3 Silver, including that in base bullion, gold bullion, etc., fine, oz. 13,543,198 17,611,646 +30.0 Zinc (nearly all refined), sh. tons. 26,545 28,199 + 6.2 Asbestos shipments, sh. tons 92,761 136,657 +47.3 Coal, all grades, sh. tons 15,057,500 15,045,300 Gypsum shipments, sh. tons 386,550 441,160 +14.1 Natural gas, M. cu. ft 14,077,600 14,954,100 + 6.2 Petroleum, bbl : 187,540 178,570 - 4.8 Cement, bbl 5,752,885 6,943,968 +21.0 Brick, structural, all kinds, M. , , 109,009 127,137 +17.0 On the basis of estimated market values, the whole output of 1922 was contributed as follows: Metals, 33.4 per cent.; non-metallic minerals, 45.1 per cent.; structural materials and clay products, 21.5 percent.; this distribution indicates a return of the metal mining. industry nearly to the position of relative importance that it occupied. before 1921, in which year metals contributed only 28.7 per cent. to the total value. of output while non-metallics gave 51.1 per cent. Canadian cobalt originates entirely in the ores of the Cobalt district, which are mainly treated at smelters in southern Ontario, although some quantities of residues have been exported to England and Europe. Exports during 1922 increased even more than production, consisting of about four-fifths . cobalt oxides and salts, and one-fifth of cobalt alloys and other metal combinations.

Jan 8, 1923

By C.P. Clingerman

The recent iastallation of a combination dust catcher, gas washer and precipitator at Carrie blast furnaces of the Homestead Steel Works has given very satisfactory results. The following description of the gas-cleaning installation is based on actual operating experience. When Carrie blast furnace No. 3 was rebuilt the decision was made to fine-clean all the gas produced by the furnace, because the management wanted fine-cleaned gas for fuel in the stoves and boilers. In order to keep the installation cost as low as possible, the gas-cleaning system was streamlined. All by-pass lines and goggle valves for bypass lines were eliminated from the system. A radical departure from the use of 8-in. tubes in the Cottrell-type precipitators was made by using 12-in. diameter tubes in a single compartment, the single compartment being divided into two units by a single partition wall in the top header. The Furnace Proper A few of the characteristic points and dimensions of the furnace proper are: Hearth diameter.............. 26 ft. o in. Bosh diameter............... 29 ft. 1 3/4 in. Stock-line diameter........... 20 ft. o in. Large-bell diameter........... 14 ft. 8 in. Small-bell diameter........... 6 ft. 6 in. Height of furnace from center of iron notch to bottom of large bell, closed............ 94 ft. 4 in. Height of furnace from center of iron notch to main platform ...................... 105 ft. o in. The furnace top is equipped with a MC-Kee revolving distributor, the operation of which is electrically interlocked with the skips, bell hoists, and coke-weighing and charging apparatus through a Freyn automatic charging control. The gas leaves the furnace first through four offtakes, 5 ft. 9 in. in diameter, then through uptakes that, are approximately 85 ft. high, which feed into a single down-comer that is 9 ft. in diameter. Dust Catcher The primary dust catcher installed (Fig. I) may be described as a single-cone type. The inlet pipe at the top of the dust catchei is 9 ft. in diameter; it is flared to a conical shape as it extends down inside the dust-catcher shell, which is 35 ft. in diameter, 37 ft. high on the straight side, and has a conical top and bottom. The slope of the bottom is so0 with the horizontal. The cone-shaped pipe inside the dust-catcher shell is 42 ft. high and is 19 ft. 7 in. in diameter at its bottom lip where it releases the gas inside the dust catcher. The ratio of the area of the inside cone at its bottom lip to the

Jan 1, 1943

By C. P. Clingerman

The recent iastallation of a combination dust catcher, gas washer and precipitator at Carrie blast furnaces of the Homestead Steel Works has given very satisfactory results. The following description of the gas-cleaning installation is based on actual operating experience. When Carrie blast furnace No. 3 was rebuilt the decision was made to fine-clean all the gas produced by the furnace, because the management wanted fine-cleaned gas for fuel in the stoves and boilers. In order to keep the installation cost as low as possible, the gas-cleaning system was streamlined. All by-pass lines and goggle valves for bypass lines were eliminated from the system. A radical departure from the use of 8-in. tubes in the Cottrell-type precipitators was made by using 12-in. diameter tubes in a single compartment, the single compartment being divided into two units by a single partition wall in the top header. The Furnace Proper A few of the characteristic points and dimensions of the furnace proper are: Hearth diameter.............. 26 ft. o in. Bosh diameter............... 29 ft. 1 3/4 in. Stock-line diameter........... 20 ft. o in. Large-bell diameter........... 14 ft. 8 in. Small-bell diameter........... 6 ft. 6 in. Height of furnace from center of iron notch to bottom of large bell, closed............ 94 ft. 4 in. Height of furnace from center of iron notch to main platform ...................... 105 ft. o in. The furnace top is equipped with a MC-Kee revolving distributor, the operation of which is electrically interlocked with the skips, bell hoists, and coke-weighing and charging apparatus through a Freyn automatic charging control. The gas leaves the furnace first through four offtakes, 5 ft. 9 in. in diameter, then through uptakes that, are approximately 85 ft. high, which feed into a single down-comer that is 9 ft. in diameter. Dust Catcher The primary dust catcher installed (Fig. I) may be described as a single-cone type. The inlet pipe at the top of the dust catchei is 9 ft. in diameter; it is flared to a conical shape as it extends down inside the dust-catcher shell, which is 35 ft. in diameter, 37 ft. high on the straight side, and has a conical top and bottom. The slope of the bottom is so0 with the horizontal. The cone-shaped pipe inside the dust-catcher shell is 42 ft. high and is 19 ft. 7 in. in diameter at its bottom lip where it releases the gas inside the dust catcher. The ratio of the area of the inside cone at its bottom lip to the

Jan 1, 1943

Established as a Division February 22, 1928 J J Golden, Chairman M Tenenbaum, Past Chairman Gerhard Derge, Chairman-Elect R W Shearman, Secretary-Treasurer AIME, 29 West 39th Street New York 18, N Y

Jan 1, 1960

UNIVERSITY OF ALABAMA University, Ala. MINING AND METALLURGICAL SOCIETY James W Stewart UNIVERSITY OF ALASKA College, Alaska MINING SOCIETY OF THE UNIVERSITY OF ALASKA Guinn Metzger UNIVERSITY OF ARIZONA Tucson, Ariz. MINERS, SOCIETY H. Krumlauf

Jan 1, 1951

BUFFALO C E Moyer, Chairman (Buffalo, N Y ) R M Jordan, Vice-Chairman H A Morlock, Secretary CHICAGO M E Nickel, Chairman (Chicago, Ill) A M Kroner, Vice-Chairman W R McLain, Secretary-Treasurer

Jan 1, 1960