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By Douglas Will Leite

O objetivo deste estudo é recuperar parte do alumínio empregado na fabricação das embalagens de medicamentos do tipo “blister”, por tratamento químico e térmico seguido de separação gravimétrica, resultando na obtenção de alumínio na forma de óxido (Al2O3). A caracterização do produto particulado metálico obtido constitui-se em um caminho para se chegar ao patamar de existência de coleta seletiva após seu descarte, diminuição deste tipo de embalagens nos aterros sanitários e/ou incineradores de lixo doméstico e posterior reaproveitamento com amplos benefícios ambientais. A caracterização morfológica do óxido de alumínio obtido foi realizada utilizando as técnicas instrumentais de ICP/AES e MEV/EDS.

Aug 7, 2018

By R. B. Barlow, J. A. C. Fortescue

Originally developed for use in mineral exploration, regional geochemical mapping based on stream (and lake) sediment sampling is showing broader application in other areas of the earth sciences and in environmental science. The purpose of this paper is to focus attention on the role of regional geochemical mapping in relation to geological and environmental studies. This is achieved using a descriptive equation for the chemical composition of a stream-sediment sample and then relating it to the use of successive approximations in geochemical and environmental investigations. The procedure is further qualified with reference to time and process in the formation of regional geochemical patterns. Examples are included of studies based on stream sediments related to bedrock geology, surficial geology, ecology and man's effect on the geochemistry of the environment. The range of applications of regional geochemical mapping in earth and environmental studies is outlined and some conclusions drawn regarding the future development of geochemical mapping under Canadian conditions.

Jan 1, 1980

By Robert Stefanko

In the context of the following report, an hazardous location can be described as any industrial area in which flammable or explosive gases, vapors, and dusts can be encountered. When electrical apparatus is used in such hazardous atmospheres, the chance of a dust or gas ignition is ever present. Consequently, in an effort to reduce the ignition hazard, several protection systems have been devised. Such systems are termed electrical hazard reduction techniques. The most widely accepted and used of these, the explosion-proof enclosure, is the principal subject of this report. However, other techniques are briefly mentioned. Hazard reduction techniques used in coal mine atmospheres (which can contain methane, coal dust, and air mixtures) are classified as Group I. The explosion-proof enclosure commonly used in mines is defined by the USBM Schedule 2G as a device that can contain internal explosions of methane-air mixtures without undergoing damage or excessive distortion and without an ignition of a surrounding methane-air mixture or discharge of flame. (100) Internationally, the definition remains the same except the words "discharge of flame" are not present. (4,5,31,42,52,76,102) The latter description often refers to flame-proof enclosure construction, but the terms "flameproof: and "explosion-proof" commonly have the same connotation. These enclosures which may not be vapor tight, are distinguished by heavy-wall cast or welded construction and bolted or threaded close fitting flanges.

Jan 1, 1974

By R. Barthel, O. Nitzsche, J. Pateiro Fernández, T. Cramer

The Hong Gai coal field in northeast Vietnam has been the main coal mining area of Vietnam for more than 150 years. Anthracite coal is produced from several open pit and underground mines situated close to the UNESCO world natural heritage site Ha Long Bay. The mining-induced environmental impacts such as dust emissions, acid mine drainage, and visual impairments due to waste dumps resulted in severe conflicts of interests regarding future land use and the protection of the world natural heritage site Ha Long Bay. Within the RAME project (Research Association Mining and Environment in Vietnam), Brenk Systemplanung is contributing to an improved environmental and sustainable planning in Vietnam's mining industry and the reduction of environmental impacts on Ha Long Bay by developing suitable and sustainable technology and planning measures (e.g. for dump construction/rehabilitation, predictive modelling, and/or monitoring) for Vietnam's leading coal producer.

Jan 1, 2011

By F. H. Froes, D. H. Warrington

Electron microscope evidence which indicates that TaC may precipitate at random sites in the matrix is presented. Initially the particles are almost spherical and coherent with the matrix. However, as they grow in conditions in which there are insufficient vacancies to relieve lattice strain, the particles rapidly lose coherency in two directions and continue to grow as plates with approximately the full lattice mismatch strain present perpendicular to the plane of the plate. The necessary relief of strain comes from dislocations loops which do not become visible until the later stages of aging. The rapid decrease of apparent strain to low values of appoximately 1 pct at small particle sizes arises not from a complete incoherency but from applying a model wrong for the particle shape and strain distribution. PREVIOUS work has shown that MC-type carbides may precipitate intragranularly in austenitic stainless steel on dislocations,1&apos;2 in association with stacking faults,3&apos;4 and randomly through the matrix,5-7 In investigations of the matrix precipitate by thin-foil electron microscopy, considerable lattice strain has been found to occur around the precipitating phase.7&apos;8 Attempts have been made to evaluate the amount of lattice strain by using the methods developed by Ashby and brown.9,10 Values of the linear strain, much less than the 17 pct theoretical mismatch (for TaC), have been reported; it has been suggested that this is due to either a loss of coherency1&apos; or vacancy absorption which occurs during either the initial nucleation or growth of the precipitate." This report is an extension of earlier work7 that dealt with the precipitation of TaC from an 18Cr/12Ni/ 2Ta/O.lC alloy after it had been quenched from 1300°C and aged between 600" and 840°C. In particular, the shape of the precipitate particles and the amount of strain in the matrix, due to the precipitate, have been studied. The work described here is part of a wider investigation of factors that affect carbide precipitation in austenitic stainless steel," details of which are to appear elsewhere. RESULTS The present investigation can be conveniently split into two aspects of the strain-fields surrounding the matrix particles: 1) information derived from the strain-field which indicates the shape and habit plane of the precipitate particles and 2) the magnitude and sign of the strain-field. The Shape and Habit Plane of the TaC Precipitate. In the early stages of aging twin lobes (normally black F. H. FROES, formerly at the University of Sheffield, Sheffield, England, is Staff Scientist, Colt Industries, Crucible Materials Research Center, Pittsburgh, Pa. D. H. WARRINGTON is Lecturer, Department of Metallurgy, University of Sheffield. Manuscript submitted November 1, 1968. IMD on white background, i.e., for the deviation parameter, S > 0) that indicate the strained region of the matrix define the position of the particles by bright field transmission electron microscopy. The actual particles were not detected until they were approximately 120Å diam; below this size they were too small to be imaged in the electron microscope. This meant that particle growth that had occurred before this stage had to be inferred from the matrix strain-field contrast. In all cases when diffraction effects were observed from the precipitate particles, a cube-cube orientation relationship (i.e., (llO)ppt Il<llO>matrix and {1ll }ppt {III} matrix) existed between the precipitate and the matrix. From the matrix precipitate particles lying along edge-on {111} planes (e.g., at A, Fig. I), the precipitates are seen to be plate-like with their diameter being roughly 18 times their thickness after 5000 hr at 650°C. However, the exact shape of the particles cannot be determined because of the masking effect of the strain-field contrast. If a dark-field micrograph, using a precipitate reflection, is studied, Fig. 2, a number of the projected images of the TaC particles [on the (110) foil surface] apear to have straight edges parallel to projected f111) planes. Thus, it appears that in the later stages of aging the TaC particles are plate-like with some tendency for the edges of the plate to be bounded by the matrix close-packed {ill} planes (though the general shape of the particles in the plane of the plate is circular and thus the "diameter" of the particles has a real physical significance). It should be noted that the bands of fine discrete particles observed in Figs. 1 and 2 are not the matrix precipitate discussed in this paper but are precipitates associated with extrinsic stacking faults3j4 occurring on (111) matrix planes. **£** ****** \ *x 23 Fig. 1—18/12/2~a/0.1~ alloy. Solution treated at 1300°C for 1 hr, water quenched, and aged 5000 hr at 650°C. The (112) directions shown are the traces of the e&e-on (111) planes. Foil normal [110]; operating reflection (331); bright field micrograph.

Jan 1, 1970

By Oswaldo Delfim

Com o aumento da exportação do minério de ferro para os mercados asiáticos e consequentes novos parâmetros nas especificações, principalmente granulométricas para o minério com maior grau de pureza, viabilizaram-se importantes mudanças no processo produtivo, como por exemplo, a classificação do minério em sua umidade natural. Os ganhos adquiridos nesta nova condição de processo vão desde o aumento da recuperação mássica (de 90 a 95 para 100%), menor investimento no Capex e Opex, além dos ganhos na área ambiental como a eliminação da água na rota do processo e das barragens de rejeitos com consequente facilidade na obtenção do licenciamento ambiental. Neste artigo apresentamos os detalhes técnicos das condições dinâmicas ideais da peneira vibratória dedicada a esta nova aplicação.

Aug 16, 2017

By D. Lawrence, H. Lawrence, G. Saevil

Plant operators in the mineral processing industry have been implementing expert systems for several years now, with the intent to increase production and reduce costs. Most systems have been installed on grinding circuits of some type and have proven that the technology is viable in that application. However, few applications on other processes have been attempted for various reasons, such as lack of reference sites, complexity of the process, lack of suitable measurements and lack of confidence in the technology. The successful application of an expert system on an Alumina Calcining kiln is the first such application in the West Indies Alumina Company (Windalco), and demonstrates how this technology can be successfully applied to other processes. The key objective of an expert system is to optimize the process. To achieve this the process must first be stabilized, followed by optimization of the operating parameters. The steps taken by this expert system to optimize the process are: • Check for abnormal conditions and deal with them using a prioritized set of special actions. • Use a selection of rule blocks to stabilize the process. • Once the process is stable, achieve additional benefits through further optimization of the process. The potential benefits that a user can expect to achieve through installing an expert system can be assessed on the basis that performance will improve from that of an "average operator" to that of the "best operator" performing at his optimum for 24 hours a day, every day. The quantifiable process benefits include: • Increased production • More consistent product quality • Reduced operating costs • Reduced standard deviation of key variables • Consistent plant operation The success of this project was measured in several ways: project implementation, realised economic benefits, and realised non-economic benefits. With a commitment to maintain the system over the long term, the longevity of the system is assured and will become an important part of the Alumina Calcining control strategy at Windalco. This paper discusses the various phases of implementing the ABB Expert Optimizer expert system, what the benefits were and the procedure that is in place to maintain the system to ensure continued long term success.

Jan 1, 2002

By Marcelo Moreira Furst Gonçalves

A qualidade superficial dos produtos lingotados continuamente está ligada diretamente aos estágios iniciais de solidificação do aço no molde. Nessa etapa do processo, os parâmetros e estratégias de oscilação são decisivos para a obtenção de produtos com qualidade superficial adequada. Assim, foi desenvolvido na Usiminas um sistema computadorizado para monitoramento dos parâmetros de oscilação do molde, de modo a fornecer subsídios para um melhor entendimento do processo. Este sistema monitora, em tempo real, o eixo vertical e as oscilações nos eixos horizontal e transversal, mesmo com baixas amplitudes. O sistema desenvolvido possibilita a obtenção dos dados com alta precisão, de forma totalmente automática e a realização de pós-tratamento de forma a se obterem valores relativos ao processo de lingotamento e funcionamento do molde.

Jul 30, 2018

By Ana Carolina Abrantes de Souza

O objetivo deste trabalho foi a obtenção de microestruturas diferenciadas a partir de simulações de distintas temperaturas de bobinamento, e o estudo da influência destas microestruturas nas propriedades mecânicas, em um aço baixo carbono com microadição de molibdênio e nióbio laminado a quente. A evolução microestrutural e mecânica foi avaliada com o auxílio de técnicas de microscopia óptica (MO) e microscopia eletrônica de varredura (MEV), testes de dureza Vickers e tração uniaxial, somado a determinação das temperaturas de transformação de fase no aquecimento (Ac1 e Ac3) em um analisador termomecânico (TMA). De acordo com os resultados obtidos, pode-se observar que as diferentes temperaturas adotadas da interrupção do resfriamento (simulando o bobinamento), foram capazes de proporcionar sutis diferenças nas microestruturas e propriedades mecânicas finais.

Jul 30, 2018

By A. Singh

The control of flotation plants is by no means trivial. Flotation is one of the most interactive minerals? processing operations. The interactive nature of flotation circuits results in oscillations of levels and hence of grades and recoveries. Also, poor level setpoint tracking and disturbances have negative influences on grades and recoveries. The result is an unstable plant with limited scope for optimization. An advanced controller, FloatStarTM, has been developed to provide tight control and to reduce the amount of disturbances in flotation levels. It has been shown on a number of plants that the system results in faster and better setpoint tracking, better regulatory control and faster settling times after start-ups and disturbances. The successful stabilization provided by FloatStar has made it easier to investigate the area of optimization on flotation circuits. Mintek has identified the need for a more meaningful set of setpoints or aeration rates to use as a basis for control than levels and have advocated flow control by looking after residence times. When the feed conditions change, the ideal solution would be an algorithm or strategy that finds the new optimum conditions rather than just having an unguided hunt from the previous point. A multivariable flow-optimizing algorithm, a new module in FloatStar, has been developed to calculate optimum level setpoints and/or aeration rates that will aim to optimize the residence times, mass pulls and circulating loads within a flotation circuit. Keywords: flotation, regulatory, FloatStar, start-up, disturbance, residence times, circulating loads

Jan 1, 2003

By P Papanastasiou, J Hadjigeorgiou, E Kyriakou

The south west area of Cyprus has a long history of slope instability problems. The location and extent of these landslides has been influenced by ground morphology, geological structure and the presence of weak rocks and cohesive soils. The main triggering mechanisms have been precipitation and/or seismic events. Landslides have contributed to the decision to relocate villages and considerable efforts have been put into maintaining the integrity of the local transportation network. This paper uses a recent case study of road embankment failure near Pentalia in southwest Cyprus to review the available tools for the analysis of slope instability. It further demonstrates how the shear strength reduction technique can be used in a finite element analysis to better visualise the slope instability mechanism of a road embankment and provide a reliable tool in selecting appropriate remedial measures.

Jan 1, 2006

By Denis G. Maxwell

INTRODUCTION It is my intention in this paper to deal with gold, uranium, diamonds, platinum, manganese, chrome, vanadium and heavy mineral sands. These are the most important strategic minerals produced by the Republic of South Africa which are not covered in other sessions of this program. In each case I have high- lighted the statistics and peculiar advantages which combine to make South Africa a vital source of these minerals. Before proceeding to give individual attention to these minerals I believe it would be useful to define what I mean by &apos;strategic&apos;. The Concise Oxford Dictionary defines strategic in the context of materials as &apos;essential for war&apos;. However it is commonly used in a much broader sense than this (often, in fact, very loosely) and I prefer to define it as &apos;concerned with the acquisition and maintenance of power, whether economic, political or military.&apos; A VITAL SOURCE In dealing with the individual minerals I have quoted statistics which are contained in Tables 1, 2 and 3. Table 1 clearly shows the absolute size of the South African mineral industry. However, it can also be used to demonstrate the importance of the industry to the South African economy if compared with the GNP in 1980 of about R60 billion. Table 4 illustrates clearly how important South Africa is as a supplier of these minerals to most of the important industrialized countries of the Western World. Gold If anyone had any doubts about the inclusion of gold in a list of strategic minerals I am sure that the above definition of &apos;strategic&apos; will convince them that it certainly belongs there. Similarly no one is likely to have any doubt about the fact that South Africa is a vital source of supply. Tables 2 and 3 show that in 1980 we had 51% of the world&apos;s reserves and accounted for 55% of world production. The figures for the Western World are considerably higher. The only other major producer, of course, is Russia, with small but significant production in the Pacific Rim area coming from Australia, Canada, Latin America, Papua New Guinea, Philippines and the U.S. All South African mine gold production is shipped in bullion form containing about 88% gold and 9% silver to the Rand Refinery which is a modern refinery with large scale units capable of refining half a ton of bullion at a time. The Refinery is equipped to produce standard &apos;good delivery&apos; gold as well as 9999 gold and 999 silver. The Refinery also produces the 22 karat blanks which are, used by the South African Mint to produce Kruger Rands. It goes without saying that the South African gold mining industry leads the world in all aspects of deep-level, narrow-reef mining technology. The industry&apos;s metallurgists, too, have a record of tenacious and continuing efforts to improve extraction to the level of the present finely honed efficient process used on all the modern mines. Uranium In 1980 South Africa had 14% of the uranium reserves of the Western World and accounted for 14% of production. In view of the paucity of data I am not in a position to estimate figures for the total world. All the other major sources of uranium in the Western World are situated around the Pacific Rim, with the U.S. and Canada already being major suppliers and accounting for 38% and 17% of Western World production in 1980. Australian production at the time was small but they have very large reserves and production is already rising rapidly. The U.S., Canada and Australia account respectively for 22%, 19% and 29% of the uranium reserves of the Western World. South Africa has been a major producer continuously for 30 years. Nearly all the uranium produced, amounting to about 115 000 tons up to the end of 1981, was a by-product or co-product of gold extraction. During that time the industry has frequently led the world in technological innovation, and has established a reputation as a reliable producer of a consistent, high-grade product. In the latter respect, it is helped by the fact that production is marketed by one company, Nuclear Fuels Corporation, which also blends, dries and calcines the product from the individual mines and samples and assays it before shipping. Diamonds Diamonds are the rock on which the South African mineral industry is founded. The discovery of diamonds in 1866 gave rise to the first major mineral industry in the country and the profits from diamond mining helped to finance the gold mining industry 20 years later. Although now overshadowed by gold, diamonds are still very important in the overall picture of mineral production and exports, as can be seen in Table 1. There are really three separate diamond markets - gem, natural industrial, and synthetic - and, to be meaningful, statistics should be provided separately. Unfortunately separate figures are not available. The figures in Tables 2 and 3 show that, for gem and natural industrial together, South Africa ranks third in the world in production and second in reserves. South Africa is a major producer of synthetics and probably ranks second in the world after the U.S. Recently, of course, Australia was the scene of a major diamond discovery and will soon become the only

Jan 1, 1982

By J. P. Rider

Operating practices and resulting production from longwall faces are continually improving. Consequently, longwall operators are continually seeking to improve the dust control capabilities on longwalls. The National Institute for Occupational Safety and Health (NIOSH) has been conducting dust surveys at longwalls throughout the country in an effort to document the types of controls that are being used and to quantify the relative effectiveness of these controls. To date, surveys have been completed at longwalls in Alabama, Colorado, Pennsylvania, Utah, and West Virginia. In addition NIOSH has been reviewing longwall dust parameters provided by mine operators to MSHA to assess the status of dust control technology being used throughout the industry. Results from the underground dust surveys and information obtained from MSHA will be summarized in this paper to provide an update on longwall dust control technology and practices.

By Gaston Gingras

"IntroductionL&apos;entretien de l&apos;equipement minier dans les mines à ciel ouvert est une activité qui est aussi vieille que I&apos;existence des mines et qui a progressé au cours des années pour suivre l&apos;évolution des techniques d&apos;exploitation. Lors de la mise en usage de s premières pelles à la va peur, celles-ci étaient généralement entretenues par I ‘équipe de quatre hommes qui était responsable de son opération. Pour les travaux plus compliqués ils utilisaient les services de machinistes qui eux savaient comment réparer Ie moteur à vapeur et couler des coussinets de ""babbit"". Les premières pelles diesel étaient entretenues de la même façon mais pour les réparations au moteur, on devait recourir au représentant du manufacturier qui était Ie seul à avoir les compétences nécessaires.Ce n&apos;est vraiment qu ‘après la deuxième guerre mondiale que I ‘usage de l&apos;équipement mobile s&apos;est répandu dans les mines à ciel ouvert pour débuter les extractions selon les méthodes que I&apos;on connaît aujourd&apos;hui.L&apos;entretien de l&apos;équipement minier de façon organisée à débute avec I ‘usage de ces machines dans nos mines. Ces machines étaient un peu primitives, petites et pas très dispendieuses a I&apos;achat. Même si la disponibilité était basse, elles fournissaient quand même un rendement qui en ces temps était acceptable. L’organisation de I ‘entretien de cet équipèrent était assez primitif et n&apos;occupait qu&apos;une place secondaire aux yeux de la direction de la mine."

Jan 1, 1988

R. S. Shoemaker: Our first question is, is there a need for a grizzly before a primary crusher? What is its effect on crusher capacity and crusher maintenance? Is it worth the extra capital cost in a crusher installation? Vincent: ASARCO has a grizzly at Mission. Utah Copper uses grizzlies ahead of their gyratories. There is some quite abrasive ore at Mission, an argillite type of rock, which has a work index of 16.5 to 20, which is getting up toward the taconite classification. We get a life of 12- 16 million tons per set of concaves or per mantle with the grizzly ahead of the crusher. At Duval Corp., some 6 miles to the south of Mission, their crusher installation on a good, hard rock does not have a grizzly, and the last information I had is they get a life of about 2 ½ -3 million tons on their mantle and concave. At Silver Bell, our other copper unit in Arizona, they do not have a grizzly ahead of the gyratory and there they get a life of about 5-6 million tons. At Utah Copper, which we all know is a fairly soft ore, relatively speaking, they get a life of 24-27 million tons with grizzlies ahead of the crushers. I think a grizzly has a very definite effect on the life of the mantle and the concaves. As far as a jaw crusher is concerned, I think that usually it is desirable to have a grizzly if it is properly designed, which means it is self- cleaning. Otherwise I would not like to see one in the circuit.

Jan 9, 1967

By M. J. Ferrante

The standard enthalpy of formation, low-temperature heat capacities, and enthalpy increments above 298 K were determined by the Federal Bureau of Mines for synthetic dawsonite [NaA1C03(OH)21. The enthalpy of formation was determined by hydrochloric acid solution calorimetry, with the result ?Hf°298 = -469.4±0.7 kcal/mole. The low-temperature heat capacities were determined from 6 to 307 K by adiabatic calorimetry. Tabulated are low-temperature values of Cp°, S°, and H.-Ho° from 3 to 298 K. The derived entropy at 298 K is S298 = 31.55±0.3 cal/deg mole. Enthalpy increments above 298 K were obtained by copper-block drop calorimetry. Tabular data of Cp°, S°, H°-H°298, -(G°-H°298)/T, ?Hf°, ?Gf°, and log Kf are given from 298 to 477 K. Enthalpies and Gibbs energies of decomposition are also reported.

Jan 1, 1976

By Hani Henein

Most metals and alloys processed undergo a solidification processing step. Increasingly, there is a growing number of solidification processing routes that involve rapid solidification of the alloy. These include strip casting, high pressure die casting, 3D printing, and atomization for the production of powders or spray formed parts. By contrast, there are few experimental techniques developed to study the solidification path of alloys during rapid solidification. Amongst these laser melting and solidification, Electromagnetic Levitation (EML) and Impulse Atomization (IA) are the most prominent. Of relevance is the formulation of the solidification path of an alloy and the resultant identification and quantification of metastable phases and their relationship to processing conditions. This typically involves the understanding of the interplay between undercooling and cooling rate for the various phases that form. This presentation will outline some of the methodologies developed to quantify phase fractions and their solidification path as a function of processing conditions using EML and IA.

Jan 1, 2016

By Sábata Marla Reis Durães Oliveira

Um dos problemas enfrentados pela maior parte das aciarias relaciona-se à redução do percentual de fósforo do aço. Reduzir o fósforo contido no aço tornou-se um requisito fundamental nas siderúrgicas que utilizam convertedores LD, devido à crescente demanda do mercado por aços especiais, como por exemplo, aços para a indústria automobilística. Durante o processo de desfosforação, as principais fases sólidas que podem se formar na escória de convertedor são CaO, MgO, silicato dicálcico (2CaO.SiO2), fosfato tricálcico (3CaO.P2O5), formado pela oxidação do fósforo, e o 3CaOSiO2.3CaOP2O5. O objetivo deste trabalho é estudar a formação destes compostos e avaliar a influência das fases sólidas formadas durante o processo de desfosforação do aço. Para isto foram analisadas quatro composições químicas de escórias com diferentes teores de CaO e FeO, sendo duas composições médias das escórias estudadas pela Usiminas, uma escória da literatura e uma escória desfosforante elaborada para pesquisa. Os resultados mostraram em quais composições ocorrem a formação das fases sólidas citadas e sua influência no processo.

Jul 30, 2018

By Michelle Lostra, Red Blanchette, Jan Babendererde, Greg Colzani

The City of Portland’s Westside CSO Project is constructing a deep tunnel system to reduce combined sewer overflows (CSO) from entering the Willamette River. Several kilometers of microtunneled pipelines connect the existing system to the new tunnel. The alignments encountered a variety of ground conditions, including fill, manmade obstructions (wood, steel piles, debris), fine-grained to dense coarse-grained materials, cobbles and boulders, all below groundwater. A slurry MTBM convertible to varying diameters, equipped with mix shield capabilities, was selected to cope with the conditions. This paper will discuss access shaft construction,

Jan 1, 2005

By Benjamin Smith Lyman

THE importance of topography to geology is so commonly underrated as to deserve to be pointed out again and again. The relation of topography to the different branches of geology may be seen best by a glance at them all. Geology is well understood to consist of the observation of facts about rocks as materials of the earth (geognosy), and the explanation of those facts (geognosy). The facts to observe are : I. GEOMETRICAL, as (1) structure, including the dip and strike at different points, the size, shape, and position of basins and saddles; (2) vertical section, that is, the thickness of rock groups and of their parts ; (3) horizontal or geographical position. 11. PHYSICAL, such as texture, whether sedimentary or crystalline ; and, if crystalline, whether granitic, porphyritic, amygdaloidal, globular, or concretionary ; whether compact or granular; coarse or fine; pervious or impervious; hard or soft; firm or tender; with cleavage or without ; massive or thin ; the microscopic structure ; also whether magnetic or not ; soluble or insoluble ; fusible or infusible ; and the constituent minerals. 111. CHEMICAL that is, the composition of the rocks and of their minerals and their affinities. IV. PALAENTOLOGICAL, as what kind of fossils are in the rocks,