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E. D. WILLIAMSON,* Washington, D. C. (written discussion?).-The paper is interesting and suggestive and the work described should he carried to completion, as it presents points of interest quite apart from the immediate application in glass manufacture. It ought to help, for instance, in throwing light on the chemical nature of glasses and on all questions of viscous flow.

Jan 11, 1919

By Joseph Ames

THERE are two distinct questions associated with the concept of temperature: one is practical, the other is theoretical. Our fundamental ideas of temperature come from our senses; we know what we mean by the words "hot" and "cold," or by saying one body is "hotter than another." But for scientific purposes words require definition. We are guided in this matter, as in all other scientific questions, by our knowledge of facts of observation. When two bodies at different temperatures are intimately associated, e.g., a hot stone is, dropped into a pail of water, our experience is that ultimately they come to the smile temperature as far as our senses can tell; the hot body becomes colder and the cold body hotter. In the case of a block of ice, immersed in, water, the ice melts, forming cold water, which then mixes with the other water, the final result being water colder than the original water. From our knowledge of the nature of heat phenomena, we learn that in this process one body loses, heat and the other gains heat, the condition of equilibrium being, one in which each body gains Is much heat as it loses. It is distinctly assumed in this statement that only two bodies are concerned in the transfer of heat, all other bodies being rendered in some way impervious to heat. The body that in the process loses heat is said to have the ?higher temperature" while the body that gains the heat is said to have the "lower temperature;" and, when thermal equilibrium is reached, the two bodies are said to have the "same temperature." Consequently, the temperature of a body may be defined, is it was by Maxwell, as "its thermal state considered with reference to its power of communicating heat to other bodies."

Jan 9, 1919

By David P. Hale, Guy W. Jordan

HIGH-IRON cements have a number of advantages over cements carrying little or no iron. The presence of iron in Portland cement aids in the manufacture of the cement and also imparts certain advantageous physical properties to the finished product. In manufacture, the presence of iron lowers the fuel consumption, increases the ease of proper burning, and lessens the destructive action of the charge on the kiln refractories. In the finished cement the presence of iron reduces the expansion and contraction, adds strength, adds increased resistance to freezing and thawing, and increases the resistance of the cement to sea or sulphate waters. During the past few years the construction of numerous dams throughout the Southeast by the Tennessee Valley Authority has stimulated the production of high-iron cements. At present a great number of specifications call for an iron cement, and the industry is supplying this demand with a Portland cement carrying approximately 5 per cent iron oxide. Several manufacturers are now making practically all of their cement of this type and a number of others manufacture it as a special cement over short periods to meet demands from the Tennessee Valley Authority and other buyers. The recent increase in the use of iron in Portland cement has created a market for iron products that previously was nonexistent. The chief sources of supply for the cement manufacturers at present are iron sand, iron sinter and slag, and ocher. The Copperhill mining district, Tennessee, supplies both iron sinter and slag for use in cement. The Cartersville district supplies iron sand, ocher, and some iron resulting from the magnetic separation of iron from barite. The advantages of these products vary according to the chemical properties of the raw materials and the methods of handling used by the different manufacturers. Where the iron is to be handled by conveying belts and in hopper cars, the iron

Jan 1, 1939

By T. C. Rao

Oil agglomeration experiments were carried out on coal fines to study the effect of process variables such as pulp density, bridging oil dosage and intensity of agitation on (i) size distribution and (ii) yield of agglomerated product. It has been observed that the growth of agglomerates follows a self-preserving behaviour and using this, a characteristic curve has been derived. This curve has been found to be independent of the process variables. It has also been noted that the growth of agglomerates follows second order kinetics. In an attempt to model the process for predicting the size distribution and yield of agglomerates at different levels of the variables, the cumulative 50 percent of the agglomerates passing size (d50) has been correlated with the variables (i) through the kinetic equation and (ii) directly. These equations, coupled with the characteristic curve can predict the size distribution of the agglomerates at any levels of the variables tested. The yield of agglomerates has been found to follow a definite relationship with d50.

Jan 1, 1984

There is no simple answer to the question, "What is the meaning of life?" The expressions of life are so multiple that life has different meanings for different spheres of thought, such as art, science, or philosophy; and it conveys a different significance to different persons, according to their individual development and interests. Life is complex from a philosophical point of view. The meaning of life is superficially positive and unmistakable only when approached from a mechanistic view- point; namely, that of biology or biochemistry, since these deal with the physicochemical basis of life processes. However, such a purely mechanistic or biochemical approach to the significance of life and the interpretation of man's behavior on the basis of purely physical laws is certain to run into trouble. Similarly, a concentration of effort upon materialistic advances in world progress is extremely dangerous. The possible consequences of splitting the atom, development of guided missiles, and possible bacterial warfare are timely examples. Man becomes more self-reliant as he extends his scientific and technologic discoveries and learns how to shape natural conditions to his own desires. When man will be able to travel to other planets in atomically propelled space ships and destroy whole worlds by pushing a button, a possibility which now seems to be within the realm of the predictable future, he will need the strong-

Jan 1, 1950

By Charles A. Kumke

THE "slot" system of mining in use at the Golden Queen mine, Mojave, Calif., does not involve any new mining methods. It is, however, a new combination and adaptation of several stoping systems in common practice. The first plans for stoping operations at the Golden Queen mine called for ordinary shrinkage stopes. The hanging wall of the vein, where exposed, is a very hard felsite with a dip varying from 50º to 70º. The vein itself is quartz, shattered and fractured enough to make it easy to drill and blast to a clean hanging wall. There is no well defined footwall. The footwall limits had to be determined by assays as the metal content faded out into the felsite. Two shrinkage stopes, each approximately 200 ft. long, were laid out and started on the 200-ft. level. One of these stopes, varying in width from 8 to 18 ft., was carried on up to the top limits of the ore, approximately 120 ft., without a break in the operation. The shrinkage system proved entirely satisfactory and low costs resulted from this operation. In the final drawing of this stope, two timbermen followed down on the ore, scaling the hanging wall clean of small fragments and placing an occasional long stull from foot to hanging wall where it was deemed necessary. Few such stulls, however, were required. The hanging wall stood up very well until the stope was entirely emptied of ore. Waste fill was then put into the stope by the glory-hole method, through a waste raise that had previously been run to surface from the middle of the stope. The second shrinkage stope ran into difficulties about 35 ft. above the sill floor. Up to this point the maximum width of the ore had been about 15 ft. The ore suddenly widened into the footwall to a distance of 40 ft. in the north end of the stope. In extending the stoping operations over this width, it was soon found that the vein material would not arch and support itself. Drilling in this end of the stope was then entirely too hazardous, and all operations were stopped. The ore was drawn through the chutes below as rapidly as possible and as soon as the stope was entirely

Jan 1, 1937

Jan 1, 1916

Ask any mineral industry executive what he considers one of the most expensive aspects of getting a product to the ultimate consumer and invariably the answer will be transportation. Some company officials say that transportation charges alone account for over half of the total cost of most products. If these judgments are correct and a recent invention turns out to be the long-awaited breakthrough that shippers have been looking for, then many producers can look forward to slashing their delivery costs by 90%.

Jan 9, 1969

By R. S. Shoemaker, F. W. McQuiston

Mineral Occurrence Treatment Method Table Page

Jan 1, 1975

Jan 1, 1945

By J. A. Herbst, J. L. Sepulveda, J. D. Miller

Lead cake, a zinc smelter flue dust residue, consists primarily of lead sulfate. Characteristic properties of lead cake were determined in order to aid the understanding of reaction mechanisms involved in bismuth removal from lead cake by sulfuric acid digestion. Sp gr (specific gravity) measurements, surface area measurements, and photomicrographs revealed that the particles of lead cake are quite porous and seem to consist of an agglomeration of submicron grains (0.4 pm) fused together in a manner similar to cement clinker. Analysis of experimental rate data, which was independent of particle size, indicates that the dissolution reaction involves two distinct, rate limiting steps. The initial stage of reaction appears to be limited mainly by intergranular diffusion of the reactant, hydrogen ion, while the latter stage of reaction appears to be controlled by diffusion of soluble reaction products through the reaction product layer of the individual grains.

Jan 1, 1979

By Alfred E. Hunt

The application of the color-method for the estimation of manganese in iron and steel, based upon the depth of the characteristic purple color of permanganic acid, was first made in this country, the writer thinks, by one of the members of the American Institute of Mining Engineers, Mr. Samuel Peters, in 1874, at the laboratory of the Bay State Iron Company, and was published by him in the Chemical News. The method is credited to him in the new edition of Crooke's Select Methods. The principle of oxidizing manganese with peroxide of lead, or other oxidizing agents, and determining the amount of manganese from the color of the purple permanganic

Jan 1, 1887

By Howard N. Eavenson

An analysis of the bituminous coal situation by an authority who traces the production, mining, safety, markets and labor trends in comparison with other fuels.

Jan 2, 1950

By Gustave E. Behr

The peculiar and changing conditions of a wartime market and the necessary governmental restrictions have resulted in an accumulation of a large amount of certain secondary metals in the tin-lead alloy class. With certain of these metals this accumulation has reached such proportions that it has been proposed that government agencies finance the creation of stockpiles of these secondaries just as stockpiles of primary metals have been created. The purpose of such financing would be to keep the secondary metal dealers engaged in collecting these metals, which they might

Jan 1, 1943

Colorado today is the largest coal producing state west of the Mississippi River. Developments around Denver began about 1860, and the building of railroads created a good market for the new industry. The development of the smelter and steel industries near Pueblo increased the demand. The available records are not complete, and all the data found are shown in Table 76. [ ]

Jan 1, 1942

By L. M. Litz

Study results are presented in which gaseous oxygen was dissolved in the leach liquor at concentrations of the order of 300 ppm. This oxygen-containing solution was injected into portions of a field being operated on a commercial basis with hydrogen peroxide as the oxidant. Comparative results indicate that uranium concentrations and production rates were essentially equivalent with these two oxidants.

Jan 1, 1983

By Herbert E. Lindberg

Laboratory-scale intact and jointed rock masses were tested in field and laboratory experiments to investigate tunnel response in high stress environments. In most of the experiments the tunnels were modeled by a rigid-plastic foam polyurethane with a crush strength of 3.4 MPa (500 psi) and emphasis was placed on jointed rock parameters: joint sets (single set of parallel plane joints versus a double set of orthogonal parallel plane joints), joint plane angle with respect to the direct loading direction, and joint spacing. Other parameters were loading stress, loading direction, and tunnel reinforcement strength. Results show quantitatively the increase in tunnel deformation in jointed compared with intact rocks, double versus single joint sets, and large versus small angle between the joint plane normal and the loading direction. A surprising result was the decreases in tunnel deformation with increases in the number of joints across a tunnel diameter. The efficacy of scale modeling with laboratory-constructed rock was tested by modeling complex reinforced concrete and steel tunnel reinforcements in jointed rock masses and comparing the results with large scale tunnels previously fielded in highly jointed granite. Tunnel response was reproduced in surprising detail, including concrete fracture, steel liner bending and fracture, and critical load to produce these responses. The scale models also allowed sectioning of the jointed rock masses to observe gross sliding along the joints that accompanied tunnel failure.

Jan 1, 1982

A permanent exhibition of mining machinery has just been opened in the Grand Central Palace, New York City. The exhibits include: Aerial tramways, amalgamation, assaying and laboratory appliances and supplies, blast furnaces, coal, coal-breaker plant, coal excavation, coal products, compressed-air plant, concentrating, crushing, cyanidation, distillation, drainage and pumping, drilling, earth excavation, electrical supplies, explosives, fire prevention, flotation, general supplies, hoisting, hygiene, welfare, iron products, leaching, mechanical conveyors, metal products, natural gas, petroleum, petroleum products, electric, steam, hydraulic, gas, air, and internal-combustion engines, power machinery, preparation of coal, pumping, refining, roasting, rock excavation, rotary drilling; boring, safety appliance, screening and washing, sizing and classifying, smelting, storage of coal, storage of petroleum, surface transportation, surveying, underground timbering, underground trans-port, ventilation, mine. This exposition is operated by the Merchants and Manufacturers Exchange of New York for the purpose of showing under one roof all lines of machinery and mechanical appliances. As for as possible, the exhibits will be shown in operation. The Advisory Committee is as follows: General Howard R. Ward and H. C. Parmelee. Coal and Coke.-Prof. H. H. Stoek, Samuel A. Taylor, Edwin Ludlow. Petroleum and Gas.-Frederick G. Clapp, Ralph Arnold.¬ Extraction of Metals.-Charles W. Merrill, E. Gybbon Spilsbury. Refractories.-Kenneth Seaver.

Jan 12, 1919

Jan 1, 1926

By S. C. Sun, D. R. Mitchell

T LTRASONICS can be used to deslime and up-grade ores, such as tungsten and tin, which slime excessively with high losses of value in the tailing and are difficult to deslime with conventional methods. Experimenta] work has been performed with a test-tube size ultrasonic classifier. Larger equip-

Jan 1, 1957