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By H. G. M. Rose

Contribution to the above paper by H. G. M. Rose* (Fellow) INTRODUCTION Dr Lawrence is to be congratulated on his most interesting and instructive paper, particularly on his suggestion for a model to increase mining productivity through improved management performance. In view of an experiment initiated in one Union Corporation mine (Mine A) and later extended to a second mine (Mine B), it might be of interest to review the many human factors involved and the initial productivity results achieved.

Jan 7, 1974

By R. T. Muller

Contribution to the above paper by R. T. Muller (Visitor) Demands are being made and pressure is being brought to bear on employers in South Africa to narrow or eliminate the wage gap between their White and Black employees. Few thinking people will dispute the fact that a constant improvement in the wages of Black personnel is essential, but this cannot be done merely by a redistribution of income in South Africa.

Jan 7, 1974

By Jean Frenay

Bacterial leaching tests have been carried out on Portugese pyritic ores containing zinc, copper, lead and silver as valuable elements. Both indigenous and isolated strains of Thiobacillus ferrooxidans were used. During the tests the factors pH, Eh and dissolved oxygen were measured and related to the leaching activity of the bacteria. Different means to estimate or determine the real bacteria concentration were examined. The influence of nutrient media and particle size has been evaluated. The role of galvanic couples was studied by electrical linking of mineralogical samples of pyrite, sphalerite and chalcopyrite. Leach residues were examined by optical microscopy to follow the mineralogical alterations during the leaching. The results show a rather good leaching of the sphalerite. However, the dissolution of copper from chalcopyrite is much more difficult, 50 % recovery never being obtained.

Jan 1, 1985

By C. Zografidis, K. Karalis, E. Devlin, S. Tabouris

"The main parameters affecting energy and electrode consumption in smelting reduction of Greek nickeliferous laterites in submerged arc electric furnaces (E/F) were investigated. Within this framework, the operational data of E/Fs, such as energy consumption indicators, electrode consumption indicators and chemical characteristics of Fe-Ni and slag, were correlated with the physicochemical characteristics of the calcine, produced by roasting reduction of laterite in rotary kilns (R/Ks), such as reduction degree, temperature, chemical composition and granulometry. The results obtained provide a significant input for further research on the modelling of the roasting reduction – smelting reduction process, which is a critical tool for energy optimization.IntroductionThe two main steps of pyrometallurgical treatment of greek nickeliferous laterites for ferronickel production include: i) drying, pre-heating and controlled pre–reduction of laterite ores with solid fuel reducing agents and fuel oil in rotary kilns (R/Ks) for the production of a calcine, and ii) smelting reduction of the calcine in open-bath submerged-arc electric furnaces (E/Fs) for the production of Fe-Ni alloy with 12-16% Ni [1].The energy absorbed from the endothermic reductive reactions of iron, nickel and cobalt oxides (Fe2O3, FeO, NiO and CoO) of the calcine with the remaining carbon in the E/Fs, corresponds to about 16% of the total energy output in the smelting reduction step [1]. This is indicative of the significance of the calcine’s reduction degree for the electric energy requirements in the E/Fs. Moreover, the chemical characteristics and the granulometry of the calcine constitute critical parameters for the energy requirements as well as the smooth operation of the E/Fs."

Jan 1, 2012

By Natasa Mitevska, Predrag Djordjevic, Zivan Zivkovic

This paper presents the results of an experimental investigation into the distribution of copper in the slag of an industrial reverberatory furnace sulfide concentrates smelting process in the copper smelter RTB Bor (Serbia). The influence of copper content in the matte, the temperature and the height of the slag on the content of copper in the slag was determined as Cuoxide, Cusulfide and Cutotal and was based on possible mechanisms for the loss of copper in a silicate slag from the smelting of sulfide copper concentrates. The greatest quantity of copper in the silicate slag was found in the form of matte particles, which were captured in the slag as a result of the “flotation” of SO2 gas which was formed by magnetite reduction with FeS at the slag–matte interphase boundary.

By G. E. Karantzavelos

Although jigging has been the subject of extensive studies, evaluation of the effect of various jigging factors on the efficiency of separation has been less comprehensive. The basic factors that affect jigging separation are reviewed, a mathematical model describing jigging kinetics is presented, and attention is focussed on the mechanisms of the stratification process. The parameters of the kinetic model (the Wei- bull distribution function) are redefined in a gravity concentration technological sense, and their values are estimated for a wide range of jigging conditions. Several mathematical relationships (regression models) are also formulated which express the dependence of total time required for the complete stratifaction of mineral particles on the operating jigging variables.

Jan 1, 1984

By Elias Rigopoulos

In the present study the reductive behavior of dust from the rotary kilns (RK), in ferronickel production from nickeliferous Greek laterites, is investigated. The study concerns dust of various origins (washing towers, electrostatic filters, polycyclones) and pellets made from the dust. Reducibility was studied in the temperature range of 700 °C to 850 °C in a laboratory tube furnace. Experimental results showed that reduction degree increases with temperature up to about 800 °C. The rate of reduction is great during the first minutes, giving a reduction degree R% equal to about 25%, in only a few minutes. After this, the rate is decreasing until it diminishes to zero after about 10-20 minutes of reaction. Maximum reduction degree achieved is 26 to 28%. Rates and reduction degrees at various temperatures are higher for the dust samples than those of the respective pellet samples. Keywords: Ferronickel, metallurgy, laterites, pellets, reduction

Jan 1, 2004

By Duclerc Fernandes Parra, Luis Filipe Carvalho Pedroso Lima, Harumi Otaguro, Washington Luiz Oliani, Hélio Fernando Rodrigues Ferreto, Ademar Benevolo Lugao

The activation of three polyethylenes, the low density, the high density and the linear low density polyethylene, was determined by means of dynamic mechanical analysis (DMA). Storage modulus and tan δ spectra were obtained as a function of the temperature from −60 to 50 °C with a heating rate of 2° min−1 at frequencies of 1, 2 and 5 Hz and measurement strain amplitude of 10−5. In the tan δ spectra, a small peak in the β region of the three polyethylenes was found and substantiated by subtracting the growing exponential background. This procedure was based on a model that associates the dislocation motion on metals under cyclic stress to vibrating strings and considering the same for the polymeric chains. For the determination of the activation energy we have utilized the frequency versus the reciprocal of the absolute temperature peak of the tan δ. The values obtained for the three polyethylenes, the low density, the high density and the linear low density were, 362 ± 12, 266 ± 9 and 197 ± 6 kJ mol−1, respectively, which were compared with those presented in the literature.

Mar 1, 2017

By Enrique Posada

"The Valle de Aburrá area, corresponds to the city of Medellín and neighboring municipalities, with more than 3 million people. The area generates a sizable amount of solid waste, which has been taken to landfills for the last 20 years. This paper proposes a model for public policy making which considers the cost and benefit of different alternatives to handle the wastes in the coming 20 years. Combinations of several alternatives: Recycling, waste reduction, waste separation, incineration, land filling with lixiviate treating and gas energy recovery, and organic waste composting are considered and modeled and the results presented as a contribution for a more rational approach to policy making than the one currently being employed.IntroductionThe author, working for INDISA S.A., acted as a consultant for the direction of planning of the Empresas Varias de Medellín in 2004. This entity has the responsibility for the handling of the solid wastes of the city of Medellín and some of the neighboring municipalities. At the present time more the 700.000 annual tons of waste are taken to the site of La Pradera, located in very rainy location (3.000 mm of precipitation per year), with complex in topography and very far away from the sources of the waste. During the work the author detected important problems that should be addressed, as follows:Lack of adequate technical administration and resources. The entity did not count with sufficient human resources to focus on the appropriate technical handling of the solid waste. The organization worked mostly with independent contractors, lacking enough coherence and integration. The internal workload was too large for the few people who had technical responsibility and this gave rise to attention problems. It is important to have clear technical procedures, technical know how and human resources, continuity in the activities. It is important to have a clear capacity to plan, to study, to make tests and monitoring, to pursuit and develop ideas, to optimize the processes and to introduce changes, to respond to environmental authorities, to the communities and to mass media and to handle the contractors. All this was basically lacking. In the case of the handling of the sanitary filling of La Pradera, for example, although the people in charge were very able and dedicated, the magnitude of the task was too large and the resources they had were insufficient. As a result, the site had at the time of the study, problems with thousands of vultures, lack of immediate cover up for the waste, uncontrolled leaching, the area being dirty and little attractive, despite being called a park."

Jan 1, 2008

An investigation was made into the mineralogical characteristics of the upper portions of the 650 and 750 copper lodes. The investigation was based on a comprehensive suite of geological specimens representing all types of mineralization encountered during mining until the end of 1954 and the chief aims of the investigation were to determine (a) the minerals present and their textures and associations, (b) the paragenetic sequence of deposition of minerals in the orebodies, (c) significant changes, if any, which could be found in the orebodies with depth, and (d) the nature and mode of occurrence of nickel in the ore. The general structure of the orebodies is outlined and their mineral composition given. 10 textures exhibited by the ore minerals are described and a paragenetic sequence of events in the formation of the copper orebodies is outlined. No decrease in the complexity of the sulphide mineral textures with depth could be seen and no evidence was found to suggest that the tenor of the ore would decrease with depth although some factors which may eventually limit the extent of the orebodies are noted. The mode of occurrence of minor elements in the orebodies is described. Notes on the occurrence of pyrite, aikinite and berthierite in the orebodies is given and the orebodies are considered to be identified with LiIidgren's mesothermal type of sulphide ore deposit in which considerable replacement of older by younger generations of sulphide minerals occurred.INTRODUCTIONA mineragraphic study was made by Stillwell and Edwards (1945) of a suite of specimens submitted by Mount Isa Mines Limited from the Mount Isa Black Star copper orebodies with a view to determining 1. the nature, extent and association of arsenic, antimonyand bismuth minerals, 2. the mode of occurrence of silver and 3. whether galena and sphalerite occurred in minute forms and below the sizes readily observed in hand specimens.

Jan 1, 1961

By Gordon S. Duncan

(New York Meeting, February, 1912 THE U. S. Geological Survey, I believe, has almost completed a study of the Harney Peak quadrangle, preliminary to the publication of a report on that, district. As I was engaged for some months on an investigation of the mode of occurrence of the ore-bearing formation in this area, it has seemed to me timely to make public the results of my study, as a contribution to the consideration of this subject. It seems scarcely necessary to describe the locality and general geology of the Black hills of South Dakota, for since 1846 many have contributed information concerning this region, some of the reports bearing such well-known names as those of Walter P. Jenney, Henry Newton, S. F. Emmons, and C. R. Van Hise, while we have only to glance at Bulletin No. 4 of the South Dakota School of Mines, in which Prof. C. C. O'Harra, of that institution, has given us a bibliography of contributions to the geography and geology of the section, to find that other well-known men have studied the district, and have given us the benefit of their researches. The U. S. Geological Survey has made geological maps of nearly the whole of the Black hills, the only quadrangle yet to be completed being, as stated, the Harney Peak district. During the late summer and autnmn of 1910, it was my lot to examine and report. on a considerable area in this neighborhood, which once had been prospected, and in some cases exploited, for tin. This paper gives an account of certain geological phenomena, noted at that time, which greatly influenced my conclnsions. The predominating formation of the district is pre-Cambrian, represented by a highly-cleaved mica-schist, usually very garnetiferous, and sometimes hornblendic. Rising like an island from the surrounding schist is a large mass of granite, known as

Jul 1, 1912

By D. Karpoff

"IntroductionUNTIL the recent discovery and development of deposits at Allard Lake, on the Lower Romaine river, practically the whole of Quebec's - and indeed of Canada's - production of ilmenite had come from deposits in the vicinity of St. Urbain, Charlevoix •county, a village about eight miles north of Bay St. Paul on the north shore of the St. Lawrence, some sixty miles below the city of Quebec (see Figure l) . Although these deposits were known nearly three hundred years ago and were worked in a small way during the years 1872-74, when a charcoal blast furnace was operated by the Canadian Titanic Iron Company for making white pig iron, it was not until 1908 that more or less continuous production commenced and has •continued to the present by the American Titanic Iron Company. The whole of the output has been exported to the United States.The ilmenite occurs in lenses •and dyke-like bodies within anorthosite. Production has come chiefly from three deposits: General Electric, Furnace, and East and West Coulombe. During 1951 -52, an extensive diamond drilling programme was carded out under the direction of the writer to test the Furnace and the East and West Coulombe deposits (Figures 2 and 3), which form part of the property of St. Lawrence Iron and Titanium Mines, Limited. The average tenor of the orebodies encountered in the course of the drilling was 38.60 per cent TiO2 and, in addition to these high-grade •bodies, there was found a very considerable tonnage of lower grade ore."

Jan 1, 1953

By F. Ajersch, M. Rigaud, M. Jallouli

"Le gonflement des boulettes d'hématite à été étudié à l'aide d'une méthode de mesure standard ISO ainsi qu'à l'aide d 'une méthode de mesure dilatométrique.La première méthode a servi à l'étude des boulettes haute silice (5% SiO2) dont l'indice de basicité (IB = CaO + MgO -i- SiO2 + Al2O3) a été ajustée soit à l'aide d'une addition de dolomie, soit à l'aide d'une addition de pierre à chaux, soit à l'aide d'une addition de ces deux composes. L'indice de basicité variait de 0.05 à 0.12. Les résultats de gonfle ment obtenus à 1000?C dans une atmosphère de 40 CO - 60 N2 ont permis de montrer qu’indépendamment de l'indice de basicité c'est la dolomie qui contribue le plus à diminuer le gonflement par rapport à la pierre à chaux. L'utilisation de l'indice de basicité comme critère de sélection des boulettes est discutée.La méthode dilatométrique a servi à l'étude du gonfle ment de deux types de boulettes préparées à partir de deux concentrés de fer et dont la teneur en silice a été fixée à 2.5% et 0 5%. Ces deux types de boulettes ont reçues les mêmes additions de liant en quantité et en nature. La détermination en continue du gonflement, à 950?C dans 40 CO - 60 N2, a permis d'une part de mieux cerner le niveau de réduction auquel correspond le maximum de gonflement et d'autre part de montrer que l’allure des courbes de gonflement est étroitement liée à la nature du liant. Une augmentation de la teneur en silice des concentres contribue à diminuer le gonflement des boulettes.Des essais de réduction de gonflement non isothermes ont été réalisés à des montées de température à 10 et 20?C/min. Les résultats indiquent que le gonflement déterminé dans les conditions non iso thermes est inferieur à celui obtenu lors des essais isothermes. On discute alors de la validité des essais standards de gonflement qui sont utilisés pour prédire le comportement des boulettes lors de leur réduction dans un haut fourneau."

Jan 1, 1983

Operating well designed and maintained surface mine haul roads is the key to minimising truck haulage costs - in itself a significant component of the total cost per tonne mined. Existing and proposed mining operations are subject to scrutiny, both from the economic and environmental perspectives. In the long run, this scrutiny returns improved efficiencies and leaner, 'greener' operations. The focus of this evolving evaluation process should and will certainly fall on haulage operations - simply by virtue of their contribution to overall cost of operations and sustainability impacts. Whilst the end result - improved efficiency and contributions to resource sustainability - is not in itself problematic, it is the route, or process followed to achieve these improvements that needs to be carefully managed. We can be guided on this journey by our understanding of how a road is designed, and, critically, the technological solutions that can contribute to a company's sustainability initiatives. This paper examines the current state of mine road design and operation, together with the economic and environmental issues associated with under-performance. The paper serves as a basis for evaluating the economic and environmental contributions that technology in road design and management can deliver to sustainable operations. Utilising innovation is the key to long-term sustainability and as a means of positioning the industry for the imminent structural changes to the economy and environment, changes which are now within the operating life of many mines, haul roads and haul trucks.

Jun 1, 2010

By Thomas B. Borak, Keith J. Schiager, Janet A. Johnson

INTRODUCTION Several major factors introduce uncertainties into the assessment of radon progeny exposure to miners using time-weighted average radon progeny concentrations: uncertainty in the measurement of radon progeny concentrations in specific areas, assignment of an individual miner's time to those areas, variation in radon progeny concentration between measurements and potential human errors involved in calculating concentrations and handling data. The currently available grab-sampling methods for determining working level were analyzed to determine the magnitude of the uncertainty due to each of these factors. For all measurement methods studied, the variation in the airborne concentration with time in operational areas of a mine is the dominant factor in the uncertainty in determining annual radon progeny exposures for individual miners. Uncertainties relating to accuracy of the method and precision of measurement were found to contribute a significantly greater portion of the total uncertainty than human errors. Under normal conditions, if the technicians performing the measurements are conscientious and well trained, human error contributes little to the total uncertainty of the radon progeny exposure determination. The primary goal of radiation monitoring is the reduction of radiation exposure to the lowest reasonably achievable level below regulatory limits. Monitoring personnel in mines should be trained not only to obtain accurate estimates of miner radiation exposures but also to recognize and, when possible, to implement correction of situations which result in unnecessarily high radon progeny exposures. ESTIMATION OF UNCERTAINTY DUE TO HUMAN ERRORS Human errors affecting the assignment of annual radon progeny exposure to individual miners can be placed in two categories: those related to the measurement of radon progeny concentration in specific mine areas and those related to estimation of occupancy time for individual miners and transcribing data to permanent records. The former are specific for the measurement method used; the latter are common to all methods. Errors in Determination of Working Level All systems for determining radon progeny concentration require measurement of several parameters, which include volume of air sampled, count rate and decay time. These quantities and appropriate constants are used in a basic equation, specific to the system, which estimates working level. An unintentional random mistake in measurement of any one of these parameters or in the selection of proper constants will contribute to the uncertainty in the determination of working level. In our analysis of human error we separated each measurement method into a sequence of independent operations, with each step subject to operator error. For each operation we estimated the probability of occurrence and the consequence of errors to obtain a resulting uncertainty. Certain types of errors result in specific consequences. For example, we assumed that an error of 5 seconds in timing of a 5-minute sample results in a fractional error of 1/60 (1.7%). Other types of errors can result in a range of uncertainty. Transposing digits read from a scaler can produce errors ranging from near zero to approximately 60%. In these cases we calculated the statistical variance for the distribution of errors. We assigned the square root of the variance divided by the mean as the consequence factor for that type of error. This is essentially the same as a coefficient of variation. The product of the probability of occurrence and the consequence factor is the fractional uncertainty in the measurement due to that particular error. The total uncertainty due to human errors is calculated by taking the square root of the sum of the squares of the uncertainties generated by all manual operations. Uncertainties Due to Human Error for the Kusnetz Method One of the techniques most commonly used to estimate working level in U.S. uranium mines is the Kusnetz method. A generalized way to express the equation used to compute WL by this method is: WL = (Net Alpha Counts)/(V)(ST)(CT)(E)(K) where: V = sample flow rate in liters/min ST = sampling time in min CT = counting time in minutes E = absolute counting efficiency K = Kusnetz conversion factor (dis/min-L per WL), as a function of decay time in minutes. The example of human error analysis presented here is based on the Kusnetz procedure having a timing sequence of 5 minutes sampling time, 40 minute decay time, 2 minute counting time. During the sampling procedure a stop watch is used to determine the timing interval. We assume that it is common to make small timing errors of a few seconds, but larger timing errors occur infrequently. Errors greater than 30 seconds are considered to be essentially non-existent since we assume that the

Jan 1, 1981

By W. R. Barclay

IN MY general contact with industry I have become more and more impressed with the need for the closest possible co-operation between engineers and metallurgists, and particularly with the need for appreciation of the work that each group is doing to assist the other. Also, I am convinced that from time to time it. is vitally important to a true perspective of human progress in all its branches, and certainly a salutary corrective of undue optimism and pessimism to endeavor to carry the mind hack over certain periods in the advance of technical knowledge, and form some kind of broad estimate of what has been accomplished in the application of science to industry in the fields with which we, as individuals or groups, may for the time being be concerned. We cannot without some appreciable mental effort realize what our forerunners have dine For us. If the young engineer or metallurgist entering industry today could be suddenly transported to a quarter of a century ago, and be compelled to work with the materials then available and within the limitations of knowledge then attained, he would, on his return to present-day life, have a much greater appreciation of what has been accomplished before lie arrived on the scene, and, what is even more important, a far more acute sense of its inherent value to his profession. I propose here merely to indulge in a general summary of the subject of improved engineering metals and alloys rather than in details, and to deal exclusively with developments within my own experience.

Jan 1, 1938

A. H. Mokken: I am pleased to have been given this opportunity to make a contribution to Dr Muller's paper tonight. The reason for this is that, at one stage in our careers, we were associates in the same undertaking. Dr Muller, then fresh from University, with a degree in pure science, had just stepped onto the first rung of the ladder, which, it was then thought, would lead him to a career in gold extractive metallurgy. However, endowed with an enquiring mind and conscious of a lack of fundamental training in general metallurgy and engineering, he felt a need for further academic study. To meet this need and, more importantly, to meet the necessary finances, he found his opportunity in steel. Armed with a bursary, he bade farewell to gold and proceeded overseas, to the University of Sheffield, to train as a steel metallurgist. The outcome of these academic efforts, which were followed by assignments in the steel industry and a further period at Sheffield, is the man we have listened to tonight-a highly qualified metallurgist who has displayed a sound knowledge of his subject. In choosing Sheffield, Dr Muller became associated with a steelmaking centre of world renown, a centre usually credited with the first systematic production of alloy steels, as far back as the 18th century. Since that time, great advances have been made in the production of alloy steels and this is especially so in the last decade or two, when major developments in civil, mechanical, electrical, aeronautical and nuclear engineering have been made possible by the development of steels with improved properties. In spite of spectacular advances in the technology of non-ferrous alloys, plastics and other materials of construction, steel has maintained its role as a pre-eminent material for engineering use. With the gradual accumulation of data on the properties of steels, and the use of thin film electron microscopy, to study the behaviour and characteristics of such phenomena as dislocations in metals and other microstructural features, the physical metallurgist appears to be approaching the stage of an exact understanding of such phenomena as strength, ductility and brittleness-a knowledge which could lead to close control of such properties and, therefore, to the attainment of the highest goals. An interesting example, illustrating the use of fundamental principles, based on physico-metallurgical research, is the development of the maraging steels developed by Bieber at the International Nickel Company. These steels have met the extreme technological requirements of the space age by providing the material for the cases of large rockets in which qualities, such as high tensile strength, toughness, workability and weldability are most important. Attractive as they might appear to be in considerations of savings of weight, cost of erection, transport of materials and foundations, the use of high strength steels has been accompanied by special problems such as brittle fracture, hydrogen embrittlement, notch-toughness and fatigue. It has been found that high strength steels, which performed acceptably in conventional tension tests, were found to undergo failure, in a brittle manner, in service. Hydrogen embrittlement has caused spectacular failures at a fraction of the normal ultimate tensile strength, and a lack of correlation between fatigue and tensile strengths has diminished the advantages to be obtained from the use of high strength steel in some applications. A new approach to the selection of materials for engineering design has resulted from a consideration of these phenomena in which strength, as such, is no longer as significant as it was previously. Parallel with the development of high strength steel has been the need for suitable techniques for joining component parts and here welding has played an

By K. K. Kelley

The first bulletin (245)3 in this series, which appeared in 1932, summarized the entropy values then available for the elements and inorganic compounds, results being listed for some 150 substances. In the interim advances in the realms of spectroscopy applicable to the determination of thermodynamic properties and in the development of methods of calculation therefrom have added many highly accurate values. Moreover, through the efforts of Prof. W. M. Latimer (286) and his coworkers, satisfactory entropy values are now available for all but a few of the common inorganic ions in aqueous solution. At the same time rapid progress has continued in the study of low-temperature heat capacities in several laboratories, In addition, compilation and correlation of data pertaining to vapor pressures (247), thermodynamic properties of carbonates (258), thermodynamic properties of sulfur and its inorganic compounds (250), and the thermodynamic properties of metal carbides and nitrides (251), which were published as members of this series, have yielded many values. As a result, over 500 usable entropy values for inorganic substances may now be tabulated. This bulletin originally was planned as a second revision of the first member of this series, the first revision (249) having appeared in 1936; however, because of requests for the explanatory section of the first bulletin from those teaching thermodynamics, it was decided to com¬bine the information in the first bulletin and its revision with the data that have appeared since 1935 and to repeat the explanatory material in somewhat more detail. The purpose of this bulletin is therefore to give the available values of the entropies at 298.1° K. of the elements and inorganic compounds, together with enough explanation of the methods employed in calculating entropies to make the results comprehensible.

Jan 1, 1941

By K. K. Kelley

The entropy values at 298.1° K. for the elements and inorganic compounds, on which sufficient data were available for calculation in 1931, were discussed in a previous publication (96).3 Since that time the specific beats at low' temperatures of many more inorganic substances have been determined, and considerable advances have been made in the realms of spectroscopy applicable to the determination of thermodynamic properties. Moreover, a critical study of the existing vapor-pressure data made by the author (98) furnishes entropy of vaporization results suitable for obtaining approximate values of the entropies of a number of gases from the entropies of the solids or liquids. Consequently, it appears worth while at the present time to supplement the former publication, giving the new values now obtainable and making such revision in the older values as the data warrant. The methods of calculating entropies were discussed in previous publications (96, 98) and will not be repeated here. ENTROPIES AT 298.1° K. FOR INORGANIC SUBSTANCES In the following pages, the same arrangement is followed as in the previous publication (96). All entropy values are expressed in 15° gram-calories per degree Kelvin per gram-formula mass of substance. The figures given for gases do not include the effect of nuclear spin, as is nearly universally customary at present. The estimates of accuracy in the case of the values obtained from heat-capacity data apply only to the existing measurements and to the necessary extrapolations as they are made. It is assumed usually that the substances are in such an energy condition at the lowest temperatures reached in the specific-heat measurements that the usual normal type of extrapolation may be made. No allowance is made for error in this assumption. The recent work on Gd2SO4. 8H2O and FeC13 illustrates the difficulties that may arise in obtaining the entropies of some paramagnetic substances. Also the data and calculations for such substances as CO, H20, and N20 show that the correct entropy is not obtained in all cases by indiscriminate application of the usual

Jan 1, 1936

By K. K. Kelley

This work is a continuation of a program of study of the measurement and correlation of fundamental thermodynamic data inaugurated several years ago by the United States Bureau of Mines. Previous bulletins in this series were concerned with (1) The Entropies of Inorganic Substances (66),3 (2) High-Temperature Specific-Heat Equations for Inorganic Substances (67), (3) The Free Energies of Vaporization and Vapor Pressures of Inorganic Substances (68), (4) Metal Carbonates-Correlations and Applications of Thermodynamic Properties (71), (5) Heats of Fusion of Inorganic Substances (69), and (6) A Revision of the Entropies of Inorganic Substances-1935 (70). The present bulletin has as its primary purpose the correlation of the thermodynamic properties of elementary sulphur and its inorganic compounds and the presentation, after careful consideration of all available information, of a self-consistent system of thermodynamic relationships for these substances. It is believed that such a set of relationships, concerning substances of such great metallurgical importance as sulphur, sulphur oxides, hydrogen sulphide, metal sulphides, and metal sulphates, is of considerable value in indicating directions of possibly profitable experimental work and in clarifying subjects of technical interest upon which direct experimental information is difficult and expensive to obtain. It cannot be doubted that many problems of technical importance that at the outset appear almost hopelessly complex or obscure either may be solved, if enough information is available, or the specific lacking information clearly indicated by the adoption of the thermodynamic viewpoint. This has been demonstrated many times in the work of the Metallurgical Division, Pacific Experiment Station, Berkeley, Calif. Even when only crude basic information is available, a semiquantitative picture often may be developed by thermodynamic means in which general trends and approximate limits of a proposed process or modification of practice may be clearly portrayed and thus used as guides in further considerations and experimentation.

Jan 1, 1937