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US 4,152,143-Continuous precipitation of cement copper from an aqueous ore leach solution mixed with pieces of iron as the precipitant Copper depositing on the pieces of iron is loosened and removed therefrom by means of constant but regulated oscillating movement of the pieces of iron in a horizontal elongated chamber, and the loosened copper is separated and collected from the mixture E Kausel and R Nissen, assigned to Klockner-Humboldt-Deutz A G May 1, 1979 8 pp (75-100) Filed 1-12-78 (868,981) (Drawings below) [ ] US 4,156,711-Removal of metal impurities from an acidic zinc or cadmium solution prior to electrolysis. Impurities such as manganese, cobalt, nickel, and thallium are selectively precipitated by contacting the solution with persulfuric acid or an ammonium or alkali metal salt thereof while maintaining a pH value of from 1 5 to 4 5 This patent is a continuation-in-

Jan 1, 1980

By Paul Gordon

It is shown that equations for grain-boundary migrntion given by Gordon and Vandermeer, based on a theory first advanced quantitatively by Lucke and Detert, satisfactorily explain recent data on both GRAIN boundary migration in recrystallization and in postrecrystallization grain growth has been the subject of extensive studies for many years. Only solute-independent and solute-dependent boundary migration during recrystallization in zone-refined, poly crystalline aluminum, and during grain growth in zone-refined tin. with the advent of zone-refining, however, has it been possible to carry out such studies on high-purity metals, and thus to delineate quantitatively the major effect On the migration rates of very small percentages of dissolved imPurities. Earlier exPerimental work almost invariably gave migration rate parameters which disagreed with theoretical predictions

Jan 1, 1963

By R. D. Groves, G. M. Potter, T. H. Jeffers

Experiments on ammonium carbonate leaching of native copper ores crushed to 1-inch size showed that in 30 days 55 percent of the copper was extracted from 0.7 percent copper conglomerate-type ore, and 85 percent was extracted from 2.1 percent copper amygdaloid-type ore. Cupric ions were not necessary to initiate leaching, and dilute solution containing only 2.2 grams per liter NH3 and 1.9 grams CO, was a suitable solvent. Copper was recovered from the leach liquor by solvent extraction and electrolysis of the strip solution. Cyclic testing of the leach-solvent extraction-electrolytic procedure is in progress on a 6-ton charge of minus 12-inch conglomerate-type ore assaying 2.2 percent copper. Oxygen is metered to the closed leach vessel as required by the leaching reaction. Initial copper dissolution was much slower than from minus 1-inch ore, but the leaching rate then markedly improved.

Jan 1, 1974

By L. Bombardieri, H. F. Mills

Iron King mine, producing gold-silver-lead-zinc-ore, is 10 miles east of Prescott, Ariz. At present the 1806 level is being developed. The echelon pat tern of ore deposit continues at depth but is less pronounced, and the orebody is now more or less continuous over 2600 ft of strike length, with widths 5 ft to as high as 26 ft where overlapping of lenses occurs in one section of the mine. Better continuity of ore at depth has encouraged systematic mining and improved plant facilities to offset higher operating costs. With favorable persistence of ore at depth, the three-compartment No. 6 hoisting shaft appeared inadequate to handle increased tonnage from greater depths, and in 1952, a four-compartment steel and concrete shaft was started. This is now at a depth of 1906 ft, and shaft pockets and loading cartridges are being installed on the 1806 level. Ore from the new shaft, hoisted in 5 ½ -ton Jeto bottom dump skips, is dumped into a 500-ton shaft bin, from which it is fed to a 16x30-in. gyratory crusher and conveyed 415 ft through an undersurface concrete gallery to the secondary crusher and conveying system supplying the 900-ton mill. Lead, zinc, and pyrite concentrates are floated, and the flotation tailings are cyanided after desliming. Waste from the new shaft is dumped into a 250-ton surge bin, fed from this bin to a 24-in. conveyor, and discharged into the glory hole above the block cave. The new shaft is served by a double-drum 400-hp hoist used for ore and waste; the No. 6 shaft conveys men and material.

Jul 1, 1956

By Carl R. Davis

The cost of mining during the past history of these mines has been excessive, principally by reason of the inefficiency of labor under the wage-system. The amount of labor performed per man was unsatisfactory; and Mr. Edmund B. Kirby, the general manager, decided to adopt the contract-system as a remedy. For this purpose the method now in use was devised by the writer (then and now the superintendent), as best adapted to the local conditions. On March 12, 1900, this system was presented to the miners of the War Eagle and the Center Star. The issue remained unsettled for several weeks,

Jan 1, 1902

By Arthur B. Cummins, Henry Mulryan

DIATOMITE is a hydrous or opaline form of silica, commonly known as diatomaceous earth, diatomaceous silica or kieselguhr. The term "infusorial earth" has lost its original meaning and today is incorrect in view of the distinctions between diatoms and infusoria. Various locality and variety names are obsolete but some retain local significance. Moler and Celite are trade names that have become associated with diatomite products from certain deposits in Denmark and near Lompoc, California. COMPOSITION Diatomite is essentially silica with some combined water (2 to 10 pct). Frequently it contains organic matter (from traces up to over 30 pct) and varying amounts of inorganic impurities such as sand, cryptocrystalline silica, clay, volcanic ash, calcium carbonate, magnesia and soluble salts. In the natural or crude state, diatomite contains from 10 to 65 pct or more of free water. Table I gives analyses of several diatomites from deposits of different types. PROPERTIES Pure varieties, either massive or stratified, are friable and porous, of low apparent density, and somewhat chalklike in appearance. Varieties containing organic matter vary from sedimentary oozes to peatlike materials. Impure varieties may be more or less claylike, sandy, calcareous or cherty. Compacted types approach porcellanite and silicified shales. COLOR-white, cream, gray, tan, brown, greenish to nearly black. HARDNES-light-weight varieties appear 1 to 1.5 because of porosity, but microscopic particles are 4.5 to 6.5. SPECIFIC GRAVITY-1.9 to 2.35. APPARENT DENSITY---dry block form, 20 to 40 lb per cu ft; dry powder, 5 to 16 lb per cu ft. CRYSTAL SYSTEM-generally amorphous (isotropic by X-ray diffraction) but frequently showing faint cristobalite pattern.67.68,70 MELTING POINT-1400° to 1650°C. STREAK-white. LUSTER

Jan 1, 1949

By R. H. Sweetser

The Committee on Evaluation of Coal for Blast-furnace Coke reports progress in the working out of the problem of evaluation. There has been no full meeting of the Committee but there have been several conferences with two or more of the members present, and the different members have expressed themselves freely on the five points that have been under consideration since the meeting of the Committee in New York on Feb. 16, 1932. The need of a method of coal evaluation, not only of coking coals but all other kinds, is obvious. Under NRA it becomes imperative that coals of the same size from the same seam be priced according to their variations in quality, especially in reference to cleanliness in respect to freedom from extraneous ash-forming materials. In looking over the correspondence that has passed between members of our Committee, it is evident that much of the confusion and misunderstanding would disappear if we could realize that practically all of the variations in value of coal from the same seam of coal are due to variations in the amounts of extraneous materials that are contained in the coal as it passes over the scales for shipment. It is not now a question with our committee as to the differentials in value, or in prices, between different kinds of coking coals or between noncoking and coking coals; our present problem is to arrive at the method for determining the scale of values of the coal from a certain coal seam according to the increase or decrease of extraneous ash and moisture from a predetermined base line adopted for that particular coal. The five points mentioned above are the same as discussed at the meeting in February, 1932, except that the temperature for determining the moisture content has been changed from 212" F. to 221" F., at the suggestion of Dr. A. C. Fieldner. The points are: 1. It is proposed that the coal industry adopt as a base line for evaluating all coals the analysis of the coal as it passes over the neighing device that determines the tonnage of coal bought and sold. 2. It is proposed that the Committee on Evaluation of Coal for Blast-furnace Coke approve the adoption of the base line for Pittsburgh seam coal presented by F. A. Jordan at the annual meeting of A.I.M.E.

Jan 1, 1934

By Walter H. Voskuil

Illinois supplies coal to seven states in the Upper Mississippi Valley —Illinois, Missouri, Iowa, Minnesota, Wisconsin, and portions of the Dakotas, Nebraska and Kansas. In this same area are marketed large quantities of coal from West Virginia, Kentucky, Pennsylvania, and elsewhere; fuel oil from the crude petroleum supplies of the Mid-Continent fields, and natural gas from Louisiana, Kansas and the Texas Panhandle. The boundaries of this "Illinois coal-market area" are determined by competition from other coal fields and from other forms of fuel. Within the area so described 90 per cent of Illinois coal is marketed. Thus in the Southwest, an abundance of fuel-oil supplies and natural gas dominates the market almost to the exclusion of coal. The westward movement of Illinois coal in Kansas, Nebraska and the Dakotas is met by an eastward flow of high-grade coals from Colorado, Wyoming and Montana. In the lake-shore counties of Minnesota and Wisconsin, the market is dominated by Appalachian coals, cheaply carried over the Great Lakes and reaching the ports of Lake Michigan and at the head of Lake Superior. Illinois coals find their largest market in the southern and western sections of these two lake states. Only small quantities of Illinois coals are shipped east of the state line. This market area is occupied entirely by the neighboring coal fields of Indiana and the Appalachian coal fields in Ohio, West Virginia, Kentucky and Pennsylvania. Illinois Coal-makket Area , With these factors in mind, the map of the Illinois coal-market area may be drawn. Within this boundary is the area that is logically and economically served by Illinois coal. However, this area is by no means exclusively dependent upon coal from Illinois mines. The preponderance. of Appalachian coal in Wisconsin and Minnesota has been mentioned. Appalachian coal, also, moves in large tonnages into Illinois itself, particularly the Chicago district. The Iowa and Missouri local coals share the market with imported coal from Illinois; throughout the market area, fuel oil and natural gas are important factors in the total energy supply.

Jan 1, 1936

By Walter H. Voskuil

Illinois supplies coal to seven states in the Upper Mississippi Valley —Illinois, Missouri, Iowa, Minnesota, Wisconsin, and portions of the Dakotas, Nebraska and Kansas. In this same area are marketed large quantities of coal from West Virginia, Kentucky, Pennsylvania, and elsewhere; fuel oil from the crude petroleum supplies of the Mid-Continent fields, and natural gas from Louisiana, Kansas and the Texas Panhandle. The boundaries of this "Illinois coal-market area" are determined by competition from other coal fields and from other forms of fuel. Within the area so described 90 per cent of Illinois coal is marketed. Thus in the Southwest, an abundance of fuel-oil supplies and natural gas dominates the market almost to the exclusion of coal. The westward movement of Illinois coal in Kansas, Nebraska and the Dakotas is met by an eastward flow of high-grade coals from Colorado, Wyoming and Montana. In the lake-shore counties of Minnesota and Wisconsin, the market is dominated by Appalachian coals, cheaply carried over the Great Lakes and reaching the ports of Lake Michigan and at the head of Lake Superior. Illinois coals find their largest market in the southern and western sections of these two lake states. Only small quantities of Illinois coals are shipped east of the state line. This market area is occupied entirely by the neighboring coal fields of Indiana and the Appalachian coal fields in Ohio, West Virginia, Kentucky and Pennsylvania. Illinois Coal-makket Area , With these factors in mind, the map of the Illinois coal-market area may be drawn. Within this boundary is the area that is logically and economically served by Illinois coal. However, this area is by no means exclusively dependent upon coal from Illinois mines. The preponderance. of Appalachian coal in Wisconsin and Minnesota has been mentioned. Appalachian coal, also, moves in large tonnages into Illinois itself, particularly the Chicago district. The Iowa and Missouri local coals share the market with imported coal from Illinois; throughout the market area, fuel oil and natural gas are important factors in the total energy supply.

Jan 1, 1936

By C. Perez-Rosales

A statistical method for determining simultaneously some of the basic geometrical characteristics of porous media such as porsity, specific surface* mean pore width, mean grain thickness and absolute permeability is presented. The proposed method is characterized by its simplicity and the minimum amount of laboratory equipment that it requires. The experimental procedure used to evaluate the various geometrical characteristics is based 'pan the 'surface analysis Of a a In view of this fact the app1icability Of the method is limited to homogeneous and isotropic materials. INTRODUCTION The behavior of a fluid flowing through a porous medium depends, among other things, upon the internal geometry of the medium; hence the importance of developing efficient methods to determine the geometrical properties of porous materials. This paper describes a statistical method to determine simultaneously some of the basic geometrical properties of porous materials such as porosity, specific surface, mean pore width, mean grain thickness and absolute permeability. The mathematical formulation has been developed that the data required to calculate the various geometrical characteristics of a sample can be easily measured by analyzing a section of the sample with an evenly spaced grid. THEORY A simple way of obtaining information about the internal geometry of a porous material is to throw a point at random over a cross-section of a sample. l-Through this procedure the porosity can be detemined.l,2 By considering that the material is homogeneous and isotropic, and that the point is dropped many times, the porosity 4 is given by where N is the total number of times the point is thrown and n is he number of times the point falls within pore areas. Another simple manner of analyzing the structural characteristics of a porous material is to superimpose an arbitrarily long line on a cross-section so that its length is evenly distributed over the surface area. Through this procedure the porosity can also be determined. If L is the total length of the line, and 1 is the sum of the lengths of the line segments within void spaces, the porosity is given by 4 = —.1.............. (2) The advantage of this type of analysis is that geometrical characteristics other than porosity can be obtained. Thus, if c represents the number of intersections between the line and the perimeter of pores, it can be shown3 that the specific surface, defined as he surface area of pores per unit bulk volume, is given by To give a proper description of the internal geometry of a porous medium, it is necessary to define quantities that characterize the notions of pore size and grain size. Unfortunately, because of the complexity of porous materials, it is difficult to give exact geometrical definitions of what is meant by the ConCePtS of "poresl' and "grains", especially when dealing with consolidated materials. Never theless, one often talks about the "size of pores" and the "size of grains" without defining accurately the terms. A possible solution to this problem follows. Assume that an arbitrarily long line is placed on a section of a sample so that the line is evenly distributed over the surface area (see Fig. 1). 1n a system like this, each line segment within a void space will be, by definition, the pore width in a given location and direction. Consequently, if the

Jan 1, 1970

By Benjamin Gildersleeve

Uniquely colored, thin-bedded quartzite is quarried between Crossville and Crab Orchard in Cumberland County, Tenn. It is produced in all sizes up to the limits of transportation from beds usually ranging in thickness from less than 1/2 in. to 6 in. The stone is very resistant to wear and weathering and is marketed throughout the country for many different purposes in exterior and interior construction. The annual production exceeds 36,000 tons, valued at nearly $1,000,000.

Jan 8, 1950

By J. P. Hirth, G. M. Pound

The flux of evaporation J from {loo) , {111), and (110) planes of silver single crystals and from poly crystalline specimens was measured at 744°C under a high vacuum using a time average weight loss method. The evaporation coefficient a was computed from the measured flux and vapor pressure data through the relationship J = aPe/21rmkT. The evaporation coefficients for the close packed planes and the poly crystalline specimens were found to be about 0.4 providing tentative confirmation of the theoretical limiting law for evaporation of metal crystals, a = 73(P/Pe) + % . The (110) planes faceted to form (111) planes, resulting in a greater evaporating area and larger a . The evaporation morphology of the plane surfaces and the surfaces of spherical single crystals is described in some detail. RECENTLY a detailed theoretical analysis of the mechanism and kinetics of metal crystal evaporation was made.1'2 A mechanism for vaporization involving the recession of monatomic ledges across a metal surface was deduced, and evaporation rate equations were derived by considering the dynamics of these ledges. In most metals, the process of evaporation is one of dissociation of atoms from ledges, surface diffusion, and desorption. The gross vaporization rate is controlled by the surface diffusion and desorption rates. It was shown that the monatomic ledges, under the action of surface diffusion gradients, tend to assume a terminal velocity and spacing. Further, it was shown that crystal edges and grain boundaries are a ready source for monatomic ledges. In the case of evaporation of large, perfect crystals with clean, low-index surfaces, the kinetic treatment1 leads to a limiting law for crystal evaporation: where J is the gross flux of vaporization, a is the evaporation coefficient, Pe the equilibrium vapor pressure, m the atomic mass, k Boltzmann's constant, T the absolute temperature, and P the actual pressure of vapor over the crystal surface. Imperfections such as grain boundaries, pores, cracks, and macroscopic steps should have the effect of causing positive departures from this limiting law. Such an imperfection is a source for monatomic ledges, which, near their origin, are closely spaced and thus give rise to higher evaporation rates there. However, under many experimental conditions,' this effect should be negligible due to the relatively low concentration of imperfections. In general, a more important cause of positive departure should be screw dislocations, and the effect of these has been considered in some detai1.2,3 Monatomic ledges emanate from points where the surface is intersected by a dislocation with a screw component normal to the surface. The dynamics of ledges arising from a screw dislocation are similar to those of ledges arising from a crystal edge. There is a perturbed region near the origin where the monatomic ledges are, under certain experimental conditions, closely spaced and the

Jan 1, 1960

By S. Paul Lindau

THREE years ago it was decided by the management to granulate the matte that is produced in the smelter of the St: Joseph Lead Co. at Herculaneum, Mo., thereby doing away with a large amount of labor in handling the matte and in subsequent crushing. On Mar. 1, 1915, the granulator was put in operation and up to Jan. 1, 1916, 18,735 tons had been, granulated. The four blast furnaces have a daily output of about 280 tons of pig lead and 100 tons of matte assaying about 11.0 per cent. Pb. It is expected that projected improvements in roasting methods will eliminate more sulphur from the charge, and cut down the matte-fall, to about one-half of the present figure. The blast furnaces are tapped into movable forehearths or settlers, 6 ft. by 4 ft. by 22 in., the slag overflowing into 27-cu. ft. slag cars which are hauled to the clump by electric locomotives. Previous to the adoption of granulation, the matte was tapped from the forehearths into small slag pots which were dumped after cooling. The matte cakes were broken with sledges, and transported to the crushing plant for fine crushing and screening. Here the matte was reduced to ¼ -in. size before being fed to the roaster bins.. A Wedge and a Holthoff mechanical furnace are used for preroasting before sintering on the Dwight and Lloyd machines. The matte is returned to the furnaces as an iron flux until the .gradually accumulating copper content reaches about 7 per cent., after which it is put aside to be concentrated in a small copper blast furnace, the resultant high-grade matte-being sold. When the matte does not settle readily from the slag, two settling devices are often used, the second one being a large catch-pot, which gathers any matte that may overflow from the forehearth, the slag then overflowing from the catch-pot into the slag cars. When full of matte, the catch-pot is removed, allowed to cool, and the contents broken and crushed.

Jan 10, 1916

By George C. Ference

Sulfur is the 13th most common element in the earth's crust, constituting approximately 0.05% of the total. It occurs naturally in its elemental form, as metallic sulfides, nonmetallic sulfates, and as combined or free sulfur in natural gas, crude oil, and coal. COMMERCIAL SOURCES Most of the sulfur that is consumed is converted into sulfuric acid before use; therefore, it is not necessary to recover sulfur solely in its elemental form. Processes for recovery are peculiar- to the types of reserves being processed. The major commercial processes as well as the general geographic locations where the appropriate reserves occur are listed in the following. It should be noted that the sulfur values may be recovered as the primary product, as a coproduct with other materials, or as a byproduct. Elemental Sulfur 1) Frasch mining is used for subterranean deposits of elemental sulfur around the Gulf Coast areas of the United States and Mexico. Generally, but not exclusively, such deposits are located in salt dome structure. 2) Autoclaving, flotation, or solvent extraction of surface deposits of elemental sulfur is practiced throughout the world. 3) Extraction and conversion of hydrogen sulfide from sour natural gas into elemental sulfur is done principally in Canada, France, and the United States. 4) Conversion of metallic sulfides from pyrites into elemental sulfur is done via the Outokumpu process in Finland. 5) Catalytic cracking and hydrocracking of sulfur-bearing crude oils to produce elemental sulfur is done worldwide. Desulfurization of refined petroleum products also yields elemental sulfur. 6) Recovery of elemental sulfur from sulfur-bearing oil sands (Athabasca tar sands) has been initiated in Canada. 7) As of this writing (1970), a plant has been constructed for the thermal decomposition of gypsum to produce elemental sulfur in the United States. Sulfuric Acid Sulfur values in the form of sulfuric acid are recovered via: 1) Recovery from smelter gases throughout the world. 2) Roasting of pyrites throughout the world with iron sinters as a byproduct. 3) Roasting of anhydrite with cement as a coproduct, primarily in Europe. 4) Processes currently are being developed for recovery of sulfuric acid from combustion gases resulting from the burning of high-sulfur-content fuel. Other Sulfur values also are recovered from waste products which normally occur in highly industrialized areas. Some examples are: coke-oven gases, sludge sulfuric acid, and pickling liquors (ferrous sulfate).

Jan 1, 1976

By C. M. Heath, B. W. Gonser

Soft solders are used principally in the automotive, can-making, building construction and electrical industries, but their field of usefulness extends well beyond these principal users to a vast list of miscellaneous applications where metal joints are required. The most common soft solders and the only ones considered in this discussion are those composed of lead and tin, with or without various relatively small percentages of impurities or additions. A small amount of antimony is often purposely added. As an indication of the importance of these lead-tin solders, 8620 long tons of tin were consumed in 1934 in the United States for making new solder, and during most of 1935 from 900 to 1000 long tons often were used each month. In addition, many thousands of tons of secondary solder are recirculated annually. A great many factors influence the properties of joints made with soft solders. Fluxes and the fluxing procedure used to prepare the surfaces to be joined in order to give a true metal-to-metal contact are among the most important of these factors. The temperatures used, cleanliness of the work and general soldering technique have their effect, but when results are unsatisfactory they are usually attributed to the metallic solder itself and the raw materials from which it is made. Sometimes criticism of the solder is justified. The wrong composition may be chosen for a given job, impurities may be present that ruin certain desired qualities, or uniformity may be lacking. A solder may even be looked upon with suspicion because of its ancestry, regardless of its true composition and behavior. To clarify the effect of slight differences in composition as found in commercially refined solders, a comparison of properties of solders grouped according to their origin has been undertaken. This investigation seeks to give practical information on the properties of tin-lead solders produced from virgin metals, from commercially refined secondary solder, and from an electrolytically refined crude

Jan 1, 1936

By Dol Duwez, R. H. Willens

A technique is described by which metastable alloy phases can be obtained by very rapid cooling from the liquid state. The results obtained so far have lead to; 1) extension of solubility limits beyond their equilibrium values, 2) new phases not found under equilibrium conditions, and 3) amorphous alloys. MANY new nonequilibrium phases have been found in alloys rapidly cooled from the liquid state. The technique used in these investigations essentially consisted of propelling a small molten globule of an alloy against the inside surface of a rotating copper cylinder. Since these original experiments were performed, the technique has been greatly improved. The purpose of this paper is to describe in detail, for the first time, a simple and efficient apparatus for producing foils of alloys which are rapidly cooled from the melt and to summarize some of the observations made on these alloys. I) FAST COOLING APPARATUS In the original fast cooling apparatus used by Duwez, Willens, and Klement,' the alloy was melted in a graphite container having the shape shown schematically in Fig. 1. A shock tube was attached to one end of the graphite part to supply the pressure for ejecting the molten globule. The globule was received on the inside of a rotating cylinder located about 0.5 in. from the exit of the graphite container. The globule trajectory made an angle of about 15 to 25 deg with the tangent to the cylinder at the point of

Jan 1, 1963

By Edward Adarns Richardson

As developed up to the end of the Great War, an airplane was essentially a mechanism of wood and fabric, joined and held together by metal fittings and fastening. The engine and accessories, wire for wheel spokes and other tension members, and the occasional use of metal for inter-plane struts and the shafts of surface controls required some metal, but essentially it was a wood and fabric structure. Attempts had been made to use metal for other purposes, such as struts in the drag-trussing of wing panels and for short interplane struts, and Junkers had produced an airplane of iron in 1915. By 1917 he was using steel tubes and duralumin sheets, securing noteworthy advantages aerodynamically and from the standpoint of weight and upkeep. He was a pioneer along lines in which progress is still being made. Principles of Airplane Construction The loaded weight of airplanes ranges from 500 lb. for the light plane of which we heard so much a short time ago, to about 40,000 Ib. The great majority of planes range from 2000 to 10,000 Ib. Of this weight from 15 to 30 per cent. is for the dividend-earning load. This percentage is so low that every per cent. saved on the rest of the weight increases the pay load from 3 to 6 per cent,. The economic value of every pound that can be saved in designing or constructing a plane is sufficiently great to warrant spending money on refined methods of structural analysis, materials of superior strength properties for a given weight, methods of manufacture which may make possible the use of refinements in structural design, and the like, to an extent unknown heretofore. The weight of the airplane, without fuel, oil and crew, and pay load, ranges from 50 to 65 per cent. of the total weight loaded for planes suitable for commercial use. It is doubtful if the structural weight will ever be brought down to as low as 40 per cent. for commercial planes. The airplane may be roughly divided into: (1) Power plant, which includes engines, radiators, cooling water, oil and fuel tanks, piping, propellers, engine-starting systems, pumps, super-

By A. D. Hoagland

The Flat Gap mine is located on Copper Ridge in the Appalachian Valley of East Tennessee. Large zinc orebodies occupy zones of solution and collapse breccias in Lower Ordovician Kingsport limestone and dolomite. The principal ore mineral is sphalerite and the principal gangue is dolomite. The ore-bearing horizons are considerably more than 95% covered by thick residual clay. Geochemical prospecting under these conditions is an effective exploration technique which played an important role in the discovery and exploration of the Flat Gap mine. The Flat Gap mine, an important zinc deposit of the Appalachian type, is located in the Copper Ridge Belt in the Valley of Tennessee approximately 30 miles northeast of the Mascot-Jefferson City zinc district (Fig. 1). The ore is found in large stratigraphically linked deposits in solution and collapse breccias of the Kingsport, Longview and, to a minor extent, Mascot formations of Lower Ordovician age. The principal ore mineral is sphalerite and the principal gangue minerals are dolcrmite and accessory pyrite. There is local minor galena and very rare barite and fluorite. The ore-bearing horizons are covered by about 20 to 100 ft or more of residual clay except where active streams have exposed bedrock. Considerably less than 5% of the favorable host rocks are exposed in outcrop, and this nearly complete soil cover creates a serious obstacle to exploration. Comprehensive surveys of the base metal content of soils furnish a useful substitute for outcrop geology, and under favorable conditions, this technique is a very valuable prospecting tool. The analysis is carried out by a titrametric dithizone method modified after the procedure described by E. B. Sandell.' This method detects

Jan 1, 1962

By Welton Crook

UNLESS present in considerable proportion, metals of the precious-metal group-other than gold and silver-are not readily detected by the methods of fire assaying usually applied to ores and metallurgical products. Platinum, when present in small quantity, will ordinarily be reported as silver unless special methods of parting are used. Other elements occurring in the gold itself are all fluxed and slagged in the assay operation and if analyses are made on bullions the melting and slagging operations to which the bullion has been subjected may eliminate most of the associated elements. On the other hand, the analysis of precipi-tate from the cyanide treatment of gold ores may reveal the presence of many unexpected elements, such as tungsten and molybdenum. It is uncertain, however, whether many of the elements present in the pre-cipitate are derived from the ore gangue or from the gold itself. No very general survey of the distribution of metallic elements in gold seems to have been made. Rose and Newman,1 in connection with the composition of native gold, say in part as follows: Gold is occasionally found alloyed with copper and sometimes also with iron, bis-muth, lead, mercury, tin, antimony, palladium or rhodium. Rhodium gold from Mexico was found to be of the specific gravity 15.5 to 16.8 and contained 34 to 43 per cent of rhodium. The native alloy of palladium, gold, and silver from Porpez con-tains 85.98 per cent of gold, 9.85 per cent palladium and 4.17 per cent silver. Mal-donite, from Victoria, contains gold 64.5 per cent, bismuth 35.5 per cent (Louis). Dana' says that native gold is usually alloyed with silver in varying amounts, and that sometimes it also contains traces of copper and iron. Rare varieties contain palladium, rhodium and bismuth. Other authors, for instance Zeigler3 and Clark,4 give similar information. Most refer-ences on the subject agree that ordinary native golds contain, in common, the elements silver, copper and iron. After completion of the work of which this paper is a record, the conclusion is reached that all ordinary native gold probably does contain these elements and, although in certain cases other elements may be found to be present, that it is difficult to

Jan 1, 1939

By Welton J. Crook

Unless present, in considerable praportion, metals of the precious-metal group—other than gold and silver—are not readily detected by the methods of fire assaying usually applied to ores and metallurgical products. Platinum, when present in small quantity, will ordinarily be reported as silver unless special methods of parting are used. Other elements occurring in the gold itself are all fluxed and slagged in the assay operation and if analyses are made on bullions the melting and slagging operations to which the bullion has been subjected may eliminate most of the associated elements. On the other hand, the analysis of precipitate from the cyanide treatment of gold ores may reveal the presence of many unexpected elements, such as tungsten and molybdenum. It is uncertain, however, whether many of the elements present in the precipitate are derived from the ore gangue or from the gold itself. No very general survey of the distribution of metallic elements in gold seems to have been made. Rose and Newman,l in connection with the composition of native gold, say in part as follows: Gold is occasionally found alloyed with copper and sometimes also with iron, bismuth, lead, mercury, tin, antimony, palladium or rhodium. Rhodium gold from Mexico was found to be of the specific gravity 15.5 to 16.8 and contained 34 to 43 per cent of rhodium. The native alloy of palladium, gold, and silver from Porpez contains 85.98 per cent of gold, 9.85 per cent palladium and 4.17 per cent silver. Mal-donitk, from Victoria, contains gold 64.5 per cent, bismuth 35.5 per cent (Louis). Dana2 says that native gold is usually alloyed with silver in varying amounts, and that sometimes it also contains traces of copper and iron. Rare varieties contain palladium, rhodium and bismuth. Other authors, for instance Zeigler3 and Clark,4 give similar information. Most references on the subject agree that ordinary native golds contain, in common, the elements silver, copper and iron. After completion of the work of which this paper is a record, the conclusion is reached that all ordinary native gold probably does contain these elements and, although in certain cases other elements may be found to be present, that it is difficult to

Jan 1, 1943