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Jan 1, 1966

By Theron Wasson

The year 1942 in Michigan was devoted largely to the development of fields discovered in 1941 but was also characterized by a great increase in prospecting for new productive horizons below the Dundee limestone. Some new fields were discovered but as yet these have shown few signs of being of major importance. Michigan's total production for 1942, of 21,754,000 bbl. of oil, as reported by the U. S. Bureau of Mines, was second only to the record year of 1939 when 22,799,000 bbl. of oil were produced. All important fields were prorated throughout the year, and it is obvious that without proration a new all-time high would have been established for the state this year. From 1925 to the end of 1942, Michigan has produced annually the following amounts of oil: Year Barrels Source 1925 4,000 1926 94,000 1927 435,000 1928 592,000 1929 4,641,000 1929 Michigan Geological Survey 1930 3,928,000 3,785,000 1932 6,925,000 1933 7,942,000 1934 0,603,000 1935 15,776,000 U.S. Bur. Mines, 1937 1936 11,928,000 U.S. Bur. Mines, 1938 1937 16,628,000 U.S. Bur. Mines, 1939 1938 19,211,000 U.S. Bur. Mines, 1938 1939 22,799,000 1940 19,764,000 1941 16,361,000 1942 21,754,000 Total 183,170,000 This tabulation shows the steady growth of the industry in Michigan since the first discovery of oil in 1925. Maes A map of the oil and gas fields of Michigan in 1941, published in the report for 1942, shows the main producing areas and should be referred to if information in regard to their location is desired.* The main producing zones were shown in the columnar section in the same publication. Development in Fields Reed City Field.—During 1942 the Reed City field, which ended 1941 with 112 producing oil wells, added 70 new producers to bring the total at the end of the year to 182 wells and 4700 proven acres. A south extension of the field developed during the year was in large part responsible for the increase. Approximately 9,000,000 bbl. of oil was produced from the field during the year, bringing the total accumulated production to the end of the year to roughly 11,750,000 barrels. Headquarters Field.—The Headquarters field, which started the year with ro producing oil wells, ended the year with 41 wells aid 1240 proven acres. Approximately 2,300,000 bbl. of oil was produced in 1942. Kawkawlin Field.—Although not a 1941 discovery, the Kawkawlin field has been actively developed on the 40-acre spacing plan during the last year, 42 producers having been completed, bringing the total number of wells at the end of the year to 77. Nearly 500,000 bbl. of oil was produced during the year.

Jan 1, 1943

By Theron Wasson

The year 1942 in Michigan was devoted largely to the development of fields discovered in 1941 but was also characterized by a great increase in prospecting for new productive horizons below the Dundee limestone. Some new fields were discovered but as yet these have shown few signs of being of major importance. Michigan's total production for 1942, of 21,754,000 bbl. of oil, as reported by the U. S. Bureau of Mines, was second only to the record year of 1939 when 22,799,000 bbl. of oil were produced. All important fields were prorated throughout the year, and it is obvious that without proration a new all-time high would have been established for the state this year. From 1925 to the end of 1942, Michigan has produced annually the following amounts of oil: Year Barrels Source 1925 4,000 1926 94,000 1927 435,000 1928 592,000 1929 4,641,000 1929 Michigan Geological Survey 1930 3,928,000 3,785,000 1932 6,925,000 1933 7,942,000 1934 0,603,000 1935 15,776,000 U.S. Bur. Mines, 1937 1936 11,928,000 U.S. Bur. Mines, 1938 1937 16,628,000 U.S. Bur. Mines, 1939 1938 19,211,000 U.S. Bur. Mines, 1938 1939 22,799,000 1940 19,764,000 1941 16,361,000 1942 21,754,000 Total 183,170,000 This tabulation shows the steady growth of the industry in Michigan since the first discovery of oil in 1925. Maes A map of the oil and gas fields of Michigan in 1941, published in the report for 1942, shows the main producing areas and should be referred to if information in regard to their location is desired.* The main producing zones were shown in the columnar section in the same publication. Development in Fields Reed City Field.—During 1942 the Reed City field, which ended 1941 with 112 producing oil wells, added 70 new producers to bring the total at the end of the year to 182 wells and 4700 proven acres. A south extension of the field developed during the year was in large part responsible for the increase. Approximately 9,000,000 bbl. of oil was produced from the field during the year, bringing the total accumulated production to the end of the year to roughly 11,750,000 barrels. Headquarters Field.—The Headquarters field, which started the year with ro producing oil wells, ended the year with 41 wells aid 1240 proven acres. Approximately 2,300,000 bbl. of oil was produced in 1942. Kawkawlin Field.—Although not a 1941 discovery, the Kawkawlin field has been actively developed on the 40-acre spacing plan during the last year, 42 producers having been completed, bringing the total number of wells at the end of the year to 77. Nearly 500,000 bbl. of oil was produced during the year.

Jan 1, 1943

By F. C. Hull

The grain size of a metal or alloy is one of the most important factors determining its properties. In steels, for example, grain size affects hardenability, toughness and machinability; in brasses, grain size is related to hardness and deep-drawing quality. In the field of heat-resistant alloys, grain size has a marked effect on ductility, creep and endurance strength. In order to determine these effects, as well as to control the properties of materials, many accurate and rapid measurements of grain size must be made. This paper presents a new and improved method for the estimation of grain size. Usual Methods OF EvaluatiNg Grain Size A frequetly used method of estimating grain size is that of comparing the image of a polished and etched specimen on the ground-glass screen of a metallographic microscope with standard grain-size charts. Several types of standards are available for use with different classes of microstructures. Geometric Grids.—The Metals Handbook' has a series of hexagonal grids ranging in size from ASTM No. I to 8. Idealized Grain Networks.—Idealized grain.boundary networks for ASTM grain sizes I to 8 are included in the American Society for Testing Materials Tentative Standard E 19 - 39 T, standard Micrographs & Metals Handbook and ASTM Tentative Standard E19-3gT contain micrographs of hypo-eutectoid and hypereutectoid steels ranging in grain size from No. I to 8. The grain size of annealed brass (diameter of the average grain in millimeters) is obtained by comparison with 10 micrographs of varying. grain size in ASTM Tentative Standard E 2-39 T. A handicap to accurate evaluation of grain size by this method is the fact that it is difficult to compare photographs in a dimly lighted room with the image on the ground-glass screen, or, if the general illumination is increased so that the printed standards may be clearly seen, the contrast of the image of the unknown is decreased. It is easier to estimate grain size by comparing a micrograph of the unknown with the grain-size standards. However, photographing every specimen on which the grain size is desired is too costly in time and materials to be practicable. For hardened steels, the Shepherd or Jernkontoret fracture grain-size standards are very accurate and useful, but this method obviously cannot be applied to ductile alloys such as brass, stainless steels and austenitic heat-resistant alloys. Jeffries' method for grain-size measurements consists of counting the number

Jan 1, 1948

By F. C. Hull

The grain size of a metal or alloy is one of the most important factors determining its properties. In steels, for example, grain size affects hardenability, toughness and machinability; in brasses, grain size is related to hardness and deep-drawing quality. In the field of heat-resistant alloys, grain size has a marked effect on ductility, creep and endurance strength. In order to determine these effects, as well as to control the properties of materials, many accurate and rapid measurements of grain size must be made. This paper presents a new and improved method for the estimation of grain size. Usual Methods OF EvaluatiNg Grain Size A frequetly used method of estimating grain size is that of comparing the image of a polished and etched specimen on the ground-glass screen of a metallographic microscope with standard grain-size charts. Several types of standards are available for use with different classes of microstructures. Geometric Grids.—The Metals Handbook' has a series of hexagonal grids ranging in size from ASTM No. I to 8. Idealized Grain Networks.—Idealized grain.boundary networks for ASTM grain sizes I to 8 are included in the American Society for Testing Materials Tentative Standard E 19 - 39 T, standard Micrographs & Metals Handbook and ASTM Tentative Standard E19-3gT contain micrographs of hypo-eutectoid and hypereutectoid steels ranging in grain size from No. I to 8. The grain size of annealed brass (diameter of the average grain in millimeters) is obtained by comparison with 10 micrographs of varying. grain size in ASTM Tentative Standard E 2-39 T. A handicap to accurate evaluation of grain size by this method is the fact that it is difficult to compare photographs in a dimly lighted room with the image on the ground-glass screen, or, if the general illumination is increased so that the printed standards may be clearly seen, the contrast of the image of the unknown is decreased. It is easier to estimate grain size by comparing a micrograph of the unknown with the grain-size standards. However, photographing every specimen on which the grain size is desired is too costly in time and materials to be practicable. For hardened steels, the Shepherd or Jernkontoret fracture grain-size standards are very accurate and useful, but this method obviously cannot be applied to ductile alloys such as brass, stainless steels and austenitic heat-resistant alloys. Jeffries' method for grain-size measurements consists of counting the number

Jan 1, 1948

By J. G. Thompson

OXYGEN, nitrogen and hydrogen are present in practically all metals in one or more of the following forms: (1) molecular gas in blowholes or blisters, (2) combined in nonmetallic inclusions such as nitrides, oxides or silicates, and (3) in solid solution in the metal. Gaseous elements, in some of these forms, are encountered in practically all metals and alloys but possibly have received most publicity in connection with iron and steel. In fact, the entire steel industry depends upon the control of the oxygen content during the refining process, as well as in the finished material, and it was only after the adoption of the use of efficient deoxidizers such as manganese that the production of good steel with a low carbon content became possible. In normally clean, sound steel the amount of hydrogen is negligible and the amounts of oxygen and nitrogen vary from a few thousandths to a few hundredths per cent. However, many of the effects attributed(27,31,40.41,53,54,55,56,62) ? to the presence of these elements are important and at first glance appear to be out of proportion to the amounts of impurities involved. The presence of oxygen is believed to affect the solubility of carbon in austenite and ferrite and thereby to affect the structure of the iron or steel. Such properties as strength, hardness, ductility, elastic limit, impact resistance, magnetic permeability, tendency toward caustic embrittlement, irregularity in carburization, the cutting life of tools, certain corrosion phenomena, the presence of flakes, seams, bands, ghost lines and hair cracks, and the tendency to age-harden, all have been attributed to the presence of oxygen.

Jan 1, 1932

By W. H. Newhouse

During the past few years the writer has been impressed by the close relation of many epigenetic orebodies with anticlinal structures. In the literature on ore deposits there is occasional mention that an oreshoot or district is on an anticline, but in most of the descriptions no weight or significance is attached to the relation, and usually the fact is concealed in a mass of structural detail. A few writers have stressed the relationship in a few districts or on a certain type of deposit. Church, Spurr, Butler, Stahl and Schuette have called attention to certain features, but the general extent of such a correlation has not been made known in any publication that the author has seen. A recent article1 on the localization of ore deposits, by well-known geologists, does not consider this common association. The author has seen in the field a number of the structural features described, and in addition has made a fairly complete review of the literature. This paper presents enough of the examples found to show the frequency of the relation to anticlines, and since only a few deposits on synclines are known, all of these of any importance of which the writer knows are mentioned. With certain qualifications which are discussed later, epigenetic ore deposits of replacement or vein type are mostly found where local upwarps of the earth's crust have taken place. Where formations antedating the ore deposits are present in the proper attitude to demonstrate vertical warping (i. e., more or less horizontal beds) the structural feature on which a mineral district, or mineralized area is located is almost always anticlinal, or domelike in nature. Some or even most of the ore deposits in a given district may be on the flanks of the upwarp, but few major districts are located definitely on downwarped areas. Synclinal basins within certain limits of size appear to be unfavorable to the type of fracturing that admits ore-bearing solutions. Replacement orebodies frequently are localized in small anticlines or domes, the size of the anticline or roll often being more or less commensurate with that of the enclosed oreshoot. This feature certainly ranks

Jan 1, 1931

By A. M. Gaudin

A GREAT number of hypotheses has been advanced to explain the complex phenomena that are encountered in flotation. In the days of bulk-oil flotation, when a large quantity of oil was employed, it was observed that the oil-mineral aggregate floated above the ore-pulp because of its lesser density. With the advent of froth-flotation this phase of the theory had to be modified to take into account the presence of air bubbles. The reason why the mineral-bearing froth of today rises to the top of flotation cells is, of course, because the air-mineral aggregate, with whatever reagent may be associated with it, is lighter than the pulp. In an attempt to explain froth-flotation the fact has been emphasized that certain minerals are wetted and therefore remain in water; while others are not wetted and therefore become associated in preference with air. Such an "explanation" does not explain facts, it merely states them; for instance, it does not explain why minerals are wetted under some circumstances and not wetted under others. Going somewhat further, the wetting or nonwetting of minerals by water has been ascribed' to differences in the angles of contact between oil droplets and mineral surface at the surface of the minerals. This explanation, however, was abandoned when soluble flotation reagents came to replace the so-called "insoluble" reagents. Another theory, sponsored about 10 years ago by Ralston,2 involves the effects of electric charges at the surface of the minerals particles and air bubbles. This theory, unfortunately, was not developed as fully as it seems desirable.

Jan 1, 1927

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Jan 1, 1938

By Fred A. Anderson, George B. Wallace, Edward J. Slebir

Auburn Dam will be a thin, double-curvature concrete arch dam about 685 ft high. With a crest length of about 4000 ft, it will be the world's longest single-arch dam. The site is located on the North Fork of the American River about 40 miles northeast of Sacramento, Calif. Construction is scheduled to get under way in 1970. In planning for the design and construction of Auburn Dam (see artist's conception), the foundation material, with its various discontinuities, is being investigated and the structural characteristics of the rock mass evaluated. The investigation and testing programs will aid in defining the pertinent geologic features and their individual and cumulative influence on the foundation. The work includes geologic surface mapping, surface trenching, core drilling, geophysics, tunneling, excavating shafts and raises, performing in-situ tests, and conducting laboratory tests on core and block samples. Competent amphibolite is the predominant material in the foundation, but significant bodies of chloritic, talcose, and metasedimentary rocks, a strongly developed jointing pattern, faults, and shear zones also affect the deformability of the rock mass. A comprehensive rock mechanics program, closely coordinated with geologic investigations as well as the engineering studies, therefore is required The rock mechanics work is a combination of many analytical studies and experimental investigations. The experimental work includes laboratory tests on core samples from holes drilled for geological studies of the entire foundation and in-situ tests performed in selected areas. The laboratory testing program evaluates the general properties of all important rock types and aids in correlating many of the key structural features encountered within the foundation. To derive maximum benefit from the field tests, they are conducted in materials which represent a

Jan 1, 1970

NEW MEMBERS The following list comprises the names of those persons who became members during the period Mar. 10, 1916 to Apr. 10, 1916. ALLEN, P. R., Pres., McAlester Coal & Coke Co., Knight Templar Bldg., McAlester, Okla. BERNARD, CLINTON PERCIVAL, Min. Engr., Care Forminiere Mission Kasai, Tschikapa, Congo Belge, W. Africa. CARPENTER, GEORGE 0., Vice-Pres National Lead Co. St. Louis Mo. CLARK, WILLIAM ANDREWS, JR., Min. Engr., Pres., Elm Orlu Mining Co., Butte, Mont. CLAYTON, CHARLES YANCEY, Asst. PrOf. of Metallurgy and Ore Dressing, Missouri School of Mines, Rolla, Mo. COHEN, JULIUS MILTON, Mgr. Croesus Gold Mines, Ltd., Matheson, Ont., Canada. CRAMER, WILLIAM BRONSON, Met. at Concentrator, Old Dominion Copper Min. & Smelt. Co., Globe, Ariz. DAHL, SIMEON H., Mill Supt., Messina Transvaal Dev. Co., Messina, Transvaal S. Africa.

Jan 5, 1916

By C. D. King

THE advances in basic open-hearth practice which have occurred during the past decade, have been principally in the direction of the physical development of larger units, decreased fuel consumption and increased length of furnace campaigns. However gratifying the economies which have resulted from these improvements are, it must be granted that like advances in chemical, physical-chemical and metallurgical knowledge pertaining to open-hearth practice would have added greatly to these already attained reductions in costs and it is the purpose of this paper to stimulate the discussion and study of these phases of cooperation and their relation to ingot yields. DEFINITION AND CALCULATION OF LOSSES In discussing basic open-hearth yields, the writer refers to the ingot yields obtained in the process of converting pig iron, scrap and ore to steel. In this conversion some scrap is produced. The difference between the total weight of ingots and scrap produced and the original metallic charge, constitutes the loss. Basic open-hearth yields vary considerably, and while some of the divergencies can be explained metal-lurgically because of differences in slag analysis, proportion of pig charges, and character of steel made, there often remain differences that apparently do not readily disclose themselves. In reconciling yields by the usual accepted methods of calculation, one is often forced to evaluate large losses as "unaccounted for." Such a system is prone to accept these large losses as inherent to the operation and not susceptible of appraisement and correction. It is obvious that if the ingot yield, plus the scrap recovered subtracted from 100 per cent. determines the loss, a drop in yield may increase the loss or the scrap, and both contribute to a monetary loss. To be sure, one can subdivide these unaccounted for losses into various components, such as metallics in slag, free Fe in slag, spillage, etc., and thereby reduce the amount of losses considered as "unaccounted for." If empirical methods could indicate with some degree of accuracy all losses, however slight, the undetermined losses become appreciably smaller and resultant calculations will check actual

Jan 1, 1929

By Horace Tharp Mann

Jan 1, 1926

By P. D. P. Hamilton

In any mining district where benefication of the ores is practiced, one can usually observe several types of flow sheets even though the various producers are milling ore from the same geological formations. It is obviously impossible to describe all the mills in the Porcupine district. However, the following description of some of them is of particular interest in that it shows where one mill has paid particular attention to corduroy blanket practice; one to gravity concentration of sulfides for intensive cyanidation of the values therein contained; one to flotation of values and cyanidation of this product only; and others where small variations of standard all-slime cyanidation practice prevail. In all cases it will be seen that cyanidation is the basic principle. Discussions involving the difference in the flow sheets and the reasons for them will always be of value to those interested in the art. The author of this article, however, believes that such discussions should originate from the operators of the mills under discussion. For this reason no comparisons or discussion will be included in the description of the mills mentioned. Should any reader of this article obtain information therefrom which will be of value to him in helping to solve his own particular problems, the author will consider that the article has satisfactorily served its purpose. All values mentioned throughout this article are based on the value of gold at $20.67 per ounce. Coniaurum Mines, Limited The ore of the Coniaurium mines consists of a mineralized schist and quartz containing about 2.5 per cent sulfides. Owing to the low grade of ore developed in the mine, extreme care has had to be exercised throughout the entire mining and milling operation in order that an operating profit might be obtained. The management, however, has been able to keep costs down, with the result that at present the outlook for the property is considerably brighter than it has been in the past. This is partly due to the fact that it is now known how to mine and treat

Jan 1, 1935

By Robert Ammon

THE milling practice at Mascot, at present, consists of dry crushing to 5/8 in., jigging, fine grinding, and flotation. The ore arrives at the mill from two mines, No. 1 mine shaft being located in the mill proper, and No. 2 mine shaft being situated about 2000 ft. east of the mill. No. 2 mine is served by a coarse-crushing plant and aerial tramway to the mill bins. In jigging the No. 2 mine ore, 50 per cent. of the mill feed is rejected by the jigs as a jig tailing ranging from 5/8 in. to 10 mesh; the balance of this ore, after removing a jig concentrate, is ground to flotation feed. In jigging No. 1 mine ore, approximately 80 per. cent. of the mill feed is rejected as a coarse jig tailing, and the balance is ground to flotation feed without the removal of a jig concentrate. The difference in the treatment is due to the fact that No. 2 mine ore carries a higher content of zinc than that from No. 1 mine. Of the total concentrates produced, 30 per cent. are made on jigs and 70 per cent. by flotation. At present, 1350 tons of No. 2 ore and 800 tons of No. 1 ore are treated each 24 hours. The recoveries for a typical week are as follows: Heads 3.55 Jig concentrates 61.30 Jig tails 0.80 Flotation concentrates 60.60 Flotation tails 0.09 Extraction 86.50 The associated minerals are a straw-colored sphalerite, dolomite, calcite, pyrite, quartz, and a small amount of greenockite, which occurs as a stain and sometimes small crystals along with sphalerite, but is comparatively rare. Pyrite is present in small quantities, usually less than 0.5 per cent.; quartz occurs in bands a few inches thick. A complete analysis of the ore is as follows:

Jan 9, 1924

By M. Van Weyenbergh, G. Van Esbroeck

THE copper mines of the Katanga region in the Belgian Congo lie along the same mineralized belt as those of Northern Rhodesia. There are two distinct types of deposits in that belt, the dolomitic and the quartzitic. In the dolomitic type the metallic minerals are found in a dolomitic limestone country rock. Through oxidation and enrichment,, large deposits of high-grade oxidized copper ores were formed, some of which are being worked by the Union Miniére du Haut Katanga. Such deposits are all in Katanga. The quartzitic deposits are found in Katanga and Northern Rhodesia. Here the primary mineralization occurred in sandstones and quartzites, in horizons stratigraphically lower than the dolomites. These rocks are not favorable to secondary enrichment and the oxidized zone is poorer than the sulphide zone, which alone contains the ore. There are also in Katanga a few ore-bearing veins. One of them is being worked in the Prince Leopold mine at Kipushi. PRINCE LEOPOLD MINE The Kipushi ore body fills a fault vein and invades the wall rocks more or less extensively by metasomatic replacement. The vein strikes north-northeast and south-southwest and dips to the west. The variable dip averages 60ºto a depth of 300 ft., and more uniformly 80º below 400 ft. In the upper section the average width is 200 ft. and below the width is about 150 ft. The length of the ore body is 2300 feet. The eastern side of the vein-the footwall-is dolomitic and contains irregular masses of ore sometimes extending 100 ft. or more from the main

Jan 1, 1939

By David Browne

THE literature dealing with the physical constants of nickel is so fragmentary and unrelated, that a synopsis presents unusual difficulties. It is only within the last few years that investigators have understood the importance of placing on record not only the determinations they have made but also the composition, physical treatment, and past history of the material investigated. For this reason much of the earlier literature is valueless. Determinations have been made of the same physical constants on samples differing widely in origin, composition, and treatment, and the results differ widely among themselves. In the first place nickel is almost as flexible a term as steel. Its physical properties are widely influenced by its composition and treatment. It absorbs large quantities of gases and is exceedingly difficult to prepare in a state of chemical purity comparable to gold, silver, or copper. It is vitally affected by thermal and mechanical treatment. Hence in the following pages the recorded literature, where quoted, must be accepted with a certain reserve and used, as far as possible, as a check on later observations, in which these important factors are noted. In every case where new determinations are given, an attempt has been made to record all available information concerning the composition and treatment of the material used so that the data may serve as steppingstones toward a wider knowledge of the properties of the metal. As this synopsis is an attempt by men of metallurgical training to do what should long before have been clone by physicists, it is to be expected

Jan 9, 1919

By A. E. Harnsberger

IT is obvious that details such as the physical and chemical properties and methods of heat-treating of the materials mentioned must be omitted in a paper on the subject of materials used in oil-refinery pumps1. Only sufficient identification is given to enable the reader to find additional information from already published data. Also, the subject covers many operating conditions, but only the most important services can be discussed here. To the oil refiner, the pumping equipment is of vital interest. Practically every refinery operation, from the charging of crude oil to a distillation unit to the shipping of refined products, involves some form of pumping machinery. Intermediate refining stages involve a great variety of pumping machinery to carry out successfully the aims of the refinery technologist. Temperatures at which oils are handled vary from -50° F. to 900° F. Pressure may vary from subatmospheric to 2000 lb. per sq. inch. The selection of the proper materials involves a careful consideration of the conditions under which the particular pump must operate. The four, most important considerations are temperature, pressure, corrosion, and abrasion or wear. Consideration of temperature may be divided into three parts: (1) extremely low temperatures of the order of -50° F.; (2) temperatures at atmospheric or slightly above; .(3) temperatures from 200° to 900° F. Pressures fall into two groups: (1) pressures reached by ordinary trade pumps of the order of. 200 lb. per sq. in., (2) extreme pressure conditions involving pressures as high as 2000 lb. Noncorrosive and corrosive oils can be treated differently. Under the latter falls corrosion in the presence of water, which will occur up to 250° F. The second type of corrosion occurs in high-temperature pumping equipment, with temperatures from 450° to 900° F., largely caused by sulfur compounds. There are also other corrosive conditions met with

Jan 1, 1935

By G. B. Craig, G. L. Montgomery

A simple technique has been developed which reveals glide dislocations in zone-refined aluminum as etch pits. The technique has been tested quantitatively by making dislocation counts on aluminum single crystals deformed in pure bending. The method has the advantage of being insensitive to the orientation of the surface under examination. A number of etchants which will reveal dislocations in annealed aluminum have been reported.'-' These etchants apparently depend on decoration of the dislocations by an impurity (probably iron) and cannot, therefore, be used to reveal fresh glide dislocations. In addition, it is unlikely that screw dislocations will be etched because of their small attraction for impurity atoms. Amelinckx6 has reported that glide dislocations located along slip traces can be revealed by fluo-rated aqua regia. This work indicated that dislocations themselves, irrespective of decoration by impurity atoms, are responsible for the etch pits. However, as a result of additional etching experiments, Wyon and Marchin7 concluded that dislocations alone are not sufficient to explain the localization of etch pits on slip lines in aluminum using chemical etch-pitting techniques. In addition, their results show that glide dislocations are revealed only on surfaces approximately parallel to a (100) axis and that not all slip systems are attacked. These observations have been confirmed by the present authors. The technique described in this article is insensitive to the orientation of the surface, and reveals dislocations on all glide systems. Fig. 1 shows a deformed region in the neighborhood of a scratch. Dislocations can be seen along three slip traces. In the present work, single crystals of zone-refined aluminum are polished for from 2 to 5 min in a chemical polishing reagent held at 100°C, as described by Herenguel and second:' H2Sol 60 pct H3PO4 30 pct HNO3 10 pet The samples are then coated with a thin oxide film by annealing in air at 450°C for 1 hr and cooling in the furnace. After deformation, dislocation etch pits are developed by immersing the specimen in the same polishing solution which is now held at a temperature of 50°C. The formation of small hydrogen bubbles indicates that etching has occurred. The sample is immediately removed from the solution. Prolonged etching results in enlargement of the pits and, in regions of high dislocation density, the overlapping and loss of resolution of individual pits. It is the experience of the authors that contact with iron will ruinously contaminate the reagent. With careful etching, dislocations separated by half a micron can be resolved optically and the method has been shown to be sufficiently sensitive to reveal dislocations produced during the pre-easy glide region of deformation, Fig. 2. A few examples of glide-dislocation configurations, as revealed by this technique, are shown in Figs. 1 to 4.

Jan 1, 1964

By Herbert H. Kellogg

DEPOSITS of high-silica kaolinite clays occur at many places in central Pennsylvania. These white clays were formed apparently by weathering of argillaceous quartzite and limestone. Their geology, distribution and use have been reported by Leighton.1 The larger deposits have been mined from time to time, and the clay, after washing to remove coarse sand, has found use as rubber filler, foundry clay, and in white cements. In general, the clay from these deposits contains too much grit (quartz) to be useful as paper filler, and the silica content is too high to make it useful as china clay for ceramic ware. Gravity methods for the separation of quartz from these clays have failed because of the extremely fine size of the quartz grains, but by the methods of froth flotation described in this paper these sandy kaolins can be made to yield a purified kaolinite that has a chemical composition close to that of good-grade Georgia kaolins, and is free enough from grit to be used as a paper filler. As by-products of the separation, a fine (-325-mesh) sand assaying 95.5 per cent Si02, and a very fine (-3-micron) clay are produced. The possible ceramic uses of these products are being investigated at The Pennsylvania State College. EXPERIMENTAL PROCEDURE The Sample.-The clay sample used in these tests was obtained from a small mine near Tyrone, Pa. It had already been washed to remove coarse sand, and represented the finished product of this small mine and washery. Microscopic examination showed that the clay was composed almost entirely of the minerals quartz and kaolinite, and that the quartz was present mostly in particles larger than one micron, while the kaolinite particles generally were less than 20 microns in size. The kaolinite and quartz particles were physically separable by blunging the clay in water with a suitable dispersant. Preparation of Flotation Feed.-By the addition of NaOH in an amount equal to 3 lb. per ton of solids, the clay was completely dispersed in water. Flotation feed was prepared by allowing a dispersed suspension (10 per cent solids) of the clay to stand for the period of time required for a 2.5-micron particle of quartz to settle from the top of the container to the bottom. After this settling period the suspension was decanted from the settled solids. The settled solids were redispersed in water and the separation was repeated once. The two fine fractions were then combined. Thus the clay was divided into a fine and a coarse fraction by size separation at approximately 2.5 microns.* The fine fraction was found to have a considerably lower sand content than the raw clay (Table I), and was not treated further. The coarse fraction formed the flotation feed for all the tests described in this paper.

Jan 1, 1945