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By Jean E. Tilden

An investigation of several trace elements distributed among sulfide minerals from deposits located in the southeastern United States was conducted. The deposits investigated are distributed within both the Blue Ridge Province and the Piedmont Province, which are contiguous geographic provinces. Twenty five deposits were examined;' eleven in the Blue Ridge Province and fourteen in the Piedmont Province. Figure 1 shows the locations of deposits investigated. In the deposits investigated, the mineral phases examined were pyrite, pyrrhotite, chalcopyrite, and sphalerite. These phases were chosen because of their relatively widespread occurrence, although no pyrrhotite was seen in the Piedmont Province. A total of 116 polished surfaces of ores were prepared, and mineral phases were collected from these surfaces for analysis. Samples were analyzed for cobalt, nickel, manganese, lead, tin, chromium, molybdenum, and gold. A total of 372 analyses were made. Trace elements were determined by atomic absorption spectrophotometry following standard procedures. In this study, trace elements are defined as those elements which are present in the mineral but which do not affect the chemical formula for that mineral. Lead is considered as a trace element only in ores where little or no lead sulfide could be identified as a distinct mineral phase.

Jan 1, 1972

By Carlandrea Albonico, Salvatore Miranda

After a brief introduction of the whole Project, the paper describes two special geotechnical engineering solutions provided within the scope of the Galataport Project, in Istanbul, Turkey. The first refers to the new quay of Salıpazarı, which is a combination of retaining structure and ground improvement, formed by a combiwall, a reinforced concrete diaphragm wall and a soil improvement by deep soil mixing (Turbojet). The second, refers to the soil improvement works executed underneath three existing buildings. Single-fluid jet grouting columns had the scope of improving the mechanical properties of the bearing soil and reducing the associated risk of liquefaction. A set of underpinning micropiles was installed in order to allow the excavation of a partial basement inside two of these three buildings. All activities were conducted from inside the existing buildings, with reduced headroom. The paper highlights the importance of employing cutting-edge technologies within the foundation engineering field and state-of-the-art electronic control devices, in parallel with the essential human expertise, in order to obtain the desired results in this high-profile Project.

Nov 1, 2022

By W. B. Gallup

"The Athabasca Bituminous Sands have been subject to sporadic investigations since the beginning of the century. It is probable, however, that much of what has been learned and achieved concerning the deposit has been accomplished in the last few years.Current exploratory techniques, generally speaking, involve a moderate amount of coring. Electrologs and often radioactive logs are run on most holes and certain types of these archieved excellent qualitative analysis when backed up by some core analysis for calibration. Exploration - is moving back from the river and consequently a permanent network of access roads has been developed within the last few years. Most of the operations take place in the winter time. There are about 90 permit holders at the present time.Some exploratory techniques are set up to go into recovery experiments where rich tar beds are found. It is probable that in the final analysis there will be several successful methods of extraction and that both mining and various in situ techniques will be applicable depending upon the problem locally."

Jan 1, 1960

By C. M. EYE

IN the spring of 1905 I was employed by Messrs. Bradley and Requa, under our fellow member, Thomas Cox, on the mill plans for the Nevada Consolidated, when an opportunity came to go to the Philippines to erect a small mill on the property of the Benguet Consolidated. This I accepted, expecting to be away eight months or so, but it was seven years before I got back. .I sailed in May, on the Coptic, having as room-mate as far as Kobe, A. E. Drucker, who was going out to Korea for the Oriental Consolidated. It was the first trans-ocean trip for either of us, and we had some rather unusual experiences. This was toward the close of the Russo-Japanese war and the Russian fleet was known to be on the way from Suez to Asiatic waters, but it was a matter of doubt whether they would risk a passage between Japan and the mainland, or take the longer but obviously safer route outside of Japan. The Coptic carried much contraband of war for Japan, so naturally did not care to meet this fleet. No definite word being available at Honolulu, we went to the Midway Islands, but the cable station there had very little information to offer, so we proceeded cautiously toward Japan. On the last afternoon out, we steamed due north at half speed for several hours, and finally sneaked into Yokohama at night, to learn that ' the Russian fleet had met the Japanese the day before and had been annihilated. We sailed over the spot in the Sea of Japan a week later, and when we got to Manila we found three of the Russian boats interned and being guarded by the monitor Monadnock and a cruiser. This was only a matter of form, as the Russians were only too glad to be there for the rest of the war, and the boats could not have gone far anyway, for they were literally shot to pieces. The Admiral's flagship had a hole within 3 ft. of the water line, for ward, through which a man could enter by stooping.

Jan 1, 1929

By Griffith. F. E., Glei

"INTRODUCTION For many years protective grounding of electrical equipment has been advocated as a means of safeguarding equipment against damage and of minimizing shock hazards to persons. Several codes are in effect covering in considerable detail the items to be observed in obtaining effective grounding in and about industrial plants. Although the coal-mining industry does not have a comprehensive code of its own covering the grounding of electrical installations, a number of States and individual coal-mining companies have issued codes, standards, or rules that include certain requirements with reference to grounding. As early as 1916, 4/ and again more recently, 5/ the Bureau of Mines recommended grounding, particularly as a means of preventing shock to men working on or around electrical equipment.It is common knowledge among electrical engineers of public utility and mining companies that connecting a wire from the frame of a machine to a rod or pipe driven into the earth does not necessarily assure desired protection of surface equipment. In fact, it has often been found necessary to use several interconnected rods and to treat the surrounding earth with salt or other chemicals before the connection to earth would have sufficiently low resistance to give satisfactory results. Even these expedients have not produced the desired results in some localities. It has also been found that ground connections initially having a low resistance may attain high resistance during some seasons of the year. In spite of such difficulties with surface equipment, it has sometimes been assumed that a mining machine resting on the floor in a coal mine is grounded by virtue of its contact with that floor. It has also been assumed by persons endeavoring to comply with grounding requirements that a peg or rod driven into the mine floor would provide a sufficiently low-resistance contact with the earth to be satisfactory as an electrode for connecting the grounding wire from frames of equipment. That both assumptions may be wholly untrustworthy has been proved by the authors in actual tests with underground machinery."

Dec 1, 1943

By N Lefebvre, M Jakeman, R Aseervatham

Semi-arid regions suffer from two afflictions; evaporation may exceed precipitation by multiples of two or more and variations in precipitation can be both extreme and difficult to predict. Many Australian mines are situated in semi-arid areas where communities are reliant upon locally sourced water or special purpose infrastructure is built as part of the mine construction. As the question of climate change looms, issues related to future water supply and sustainable water management become increasingly important. Across Australia several mining operations co-exist in a single surface water and/or groundwater catchment area. The management of water on a mine by mine or a community by community basis is illogical and must be reconsidered based on a single water catchment and a whole-of-community basis. Mine water should be considered on a full life cycle basis where the quality is assessed for specific mine site applications. This paper addresses technical challenges that include surface water and groundwater supply in semi-arid regions, operational water in the mining industry, beneficial uses of water, water economics and demand management. In much the same way as emissions trading evolved into a multi-stakeholder forum, mining regions offer scope for innovative thinking in water supply and reuse. In addition, this paper considers a number of initiatives taken by Australian mining companies that are entering a prefeasibility stage and contrasts these initiatives against the established success within a South African mining region. The challenges and potential solutions to this initiative are presented for future consideration.

Jan 1, 2006

By Richard D. Hagni

The United States is dependent upon foreign sources for more than 93% of its bauxite and alumina supply. Domestic production of bauxite, which comes from Alabama, Georgia and Arkansas, is limited to those bauxite ores containing less than about l ½ % iron. Bauxites with higher iron contents are generally not utilized because they cause problems in bauxite calcining and especially because they produce undesirable brick discoloration and cracking. In order to improve beneficiation and expand the utilization of high-iron or ferruginous bauxites, a mineralogical and textural study has been conducted on selected samples from the Eufaula, Alabama, bauxite district. Reflected light microscopic, petrographic, and X-ray techniques have shown that a variety of iron minerals are present, including hematite, goethite, lepidocrosite, siderite, pyrite, marcasite, and ilmenite. Although the iron minerals may be locally concentrated into concretions and pisolites, most occur as very fine grains that are disseminated and show a variety of intergrowths. Mineralogical and textural observations indicate that the fine-grained iron mineral grains may be amenable to high gradient magnetic separation.

Jan 1, 1981

By P. W. Bridgman

Flow and fracture are admittedly complicated phenomena of which we are yet only partially masters. There is not even nni-.persal agreement as to the details of the language best adapted merely to describe the phenomena, to say nothing of any theory. Certain points of view, however, are widely held, and there are certain general expectations as to what sort of procedures will prove permissible. A complete description of any situation involving fracture would demand a complete history of all the variables in the control of the experimenter. The experimenter endeavors so to choose his independent variables that they are adequate to determine completely the situation in the sense that when an experiment is repeated on the same initial material and with the independent variables running through the same sequence, all the other measurable properties of the system will also run through the same course. It is, I think, the universal conviction that when we are dealing with phenomena of flow and fracture, the most important of the necessary variables are the external forces acting on the various parts of the body; when the force history repeats, with certain obvious restrictions such as that temperature must be constant and non-mechanical forces, such as magnetic field, must be small enough to be ineffective, then the history of all measurable properties will repeat; in particular the alteration of geometrical shape due to flow will run through the same course, and when fracture comes, the character of the fracture will be reproduced. Complete mastery of merely the descriptive aspects of flow and fracture would demand the ability to predict the entire course of flow and complete characterization of the final fracture for every possible combination of forces, varying in time in all possible ways, when applied to bodies of all possible shapes. This full situation is obviously of prohibitive complexity. The first stage in reduction to manageable simplicity is to resolve the total situation into the sum of contributions made by small elements. Our thesis is that if each of the elements is adequately characterized, the behavior of the whole system is fixed. The element is usually taken of a simple geometrical shape, suggested by the mathematics best adapted to the particular situation. The forces acting across the faces of the elements are ultimately determined by the forces acting across the free faces of the whole system. The detailed process of finding the precise forces on the faces of all the elements in terms of the external forces involves the use of a special mathematical invention, the stress, a constructional quantity consisting of six components. The stress at any point in the body is determined by both the external force system and by the physical properties of the body at all points; quite different stresses prevail at the interior of bodies of the same shape under the same external forces in the elastic and plastic ranges. The forces on the faces of any element are, however, uniquely determined by the stress system at the element. Our fundamental thesis

Jan 1, 1945

By Mauro Chiesa

A. New Dictionary, Since 2007/8 Traditional concept of ?cycle? is dead A dearth of projects AND good metal prices suggests otherwise In a depletion-business, good times for any greenfields in 2-3 yrs! ?Balance? sheet means quality assets = quality capital So, de-risk the assets, and ration the capital ?Replacement costs > historical costs ?Discounted assets depleting; replacement costs need self-financing (FCF) ?Public-sector slows permits, avoids assets and wants more of FCF ?Capital ?markets? are now ?market fragments? ..and? ??Shareholder? has changed from ?growth? to ?income + performance? ?Higher search costs, higher capital costs and higher cost of capital

May 1, 2013

The paper will review the marked upsurge in the installation of new continuous metal coating lines, both hot dip and electrodeposition. Although some of this new capacity has been replacement for obsolete facilities or directed at traditional markets, eg building products, consumer durables etc, by far the major portion is targeted at the automotive industry. The reasons for the rapid growth of coated automobile panels are discussed. A comparison of the installed capacity with projections for this market indicate that a severe over-supply situation has arisen. Many coatings are now available for the automotive industry, each with their own strengths and weaknesses, but none as yet wholly satisfactory. Coating development has mainly been cost driven. This favours hot dipped coatings, providing surface quality and pressing problems can be overcome. The high cost per unit thickness of electrodeposited coatings has also seen pure zinc coatings being replaced by thinner, more corrosion resistant alloy coatings such as zinc-nickel and zinc-iron. Recently resin overlays have been introduced to improve the performance of electrodeposited coatings. Developments in coatings for the more traditional markets will be described. The fastest growing market in the last decade has been prepainted product for the building industry. This has led to the installation of extra painting capacity and again it appears an excess capacity situation has occurred. Over the same period the traditional zinc coatings have continued to lose market share to the zinc/aluminium alloy coatings, Galvalume and Galfan. These have been joined recently by '1'aiyo Crack-Free which has been taken up by some metal coaters. Galvalume is now widely accepted as being the best available coating for unpainted applications. It is also suggested that 'spin-off' coatings from automotive developments might find a niche in the consumer durable market. The end users of coated products, particularly the automotive industry, have demanded improvements in quality, such as surface smoothness, formability, etc. At the same time the new coating lines have to process wider strip and run at faster speeds. To reconcile these somewhat incompatible needs has required numerous process improvements, many of which need in-line instrumentation and computer control. The more important of these changes are discussed briefly. Finally the paper will describe the recent developments which have occurred in continuous galvanising in Australia and put them into context with the rest of the world.

Jan 1, 1993

By F. W. Bradley

This chapter on the Alaska Juneau mill is intended to make clear that "choice of methods," or the selection of proper methods, is the first essential step in launching a new enterprise; and to illustrate that when entering into new country where local conditions and physical features are new or strange to an engineer, he should respect the practices already adopted and followed in meeting peculiar conditions in these new countries that may seem strange to a casual visitor. For example, Americans going into Malay Peninsula with their most up-to-date machinery for drilling placer prospect holes found their cost to total about $3 per foot; by adopting native methods, it was found the same work could be done for 50 cents per foot. Also, those not used to frozen road conditions in a country of arctic climate might scrape the snow off such a road and cause unending road troubles into the following spring and summer; while natives understanding local conditions would leave the snow on the road. So in the neighborhood of Juneau, Alaska, where successful gold-milling operations had been going on for

Jan 1, 1932

By E. S. Bianchin

The more complex control needs of today's mineral processing plants combined with ever-changing digital technology have brought numerous improvements to process control systems. This paper discusses recent advancements in distributed control systems (DCS) which facilitate the implementation of process plant automation. Some of the topics of discussion include integrated function controllers, weigh scale and analyzer interfacing, operator interfacing, personal computers, process information management and process plant management.

Jan 1, 1988

By K. V. Raj, T. Bhowmick

"Computational fluid dynamics (CFD) modeling of an open-pit mine has several challenges. A good quality mesh of the model domain is a pre-requisite for convergence in solution. Good quality tetrahedral meshing and insertion of prism layers in faceted open-pit mine geometry is complicated due to presence of numerous vertices and ridges. Presence of vertices and ridges result in poor quality tetra elements and holes in prism layers, which cause instability in the model. Good quality pit bottom prism mesh elements significantly improve the formation of velocity boundary layer and thermal boundary layer at the pit bottom. This results in an expected temperature dependent micrometeorological buoyancy flow in the pit. Whereas, model geometry without a prism layer, results in abrupt temperature gradient near pit bottom. Buoyancy flow and recirculation have significant effect in lifting mechanism of fugitive dust particles generated near pit bottom. Representative initial and boundary conditions and selection of appropriate turbulence model have significant influences on the simulation results. In this paper, three-dimensional models of open-pit mines are developed using commercial CFD software (CRADLE-CFD). Important constraints and various consequences in modeling complex open-pit geometries are presented. INTRODUCTION Application of Computational fluid dynamics (CFD) to model an open-pit mine to predict fugitive dust and pollutant concentrations in and around a mine is relatively new. In former Soviet republic (USSR), Baklanov [1] and Belousov [2, 3] presented numerical models of pollutant transport in open-pit mines in Arctic regions. In recent years, advances in mathematical and computational fields have enabled better modeling of pollutant dispersion phenomenon around mines using computational fluid dynamics (CFD). Several CFD software packages have been used by various researchers to model the pollutant transport in open-pit mines. Works by Alvarez et al. [4]; Lowndes et al. [5]; Silvester et al. [6]; Torno et al. [7]; Choudhury and Bandopadhyay [8]; Collingwood et al. [9]; Raj et al. [10] and Flores et al. [11]; are examples of application of various commercial and open source CFD packages (COMSOL, ANSYS, OpenFOAM) to model pollutant transport in open-pit mines. These researches provided a strong background for additional research involving CFD modeling of open-pit mines. Due to the limitations of computational times and capacity, 3D modeling and various aspects of fugitive dust dispersion in open-pit mines remained unexplored."

Jan 1, 2015

"The Dumont deposit is a large (1066 Mt probable reserve) low grade (0.27% nickel), nickel sulphide project located in the Abitibi region 25km west of Amos, Quebec. Royal Nickel Corporation acquired the project in 2007 and has since taken the deposit through pre-feasibility. And updated, revised pre-feasibility was released in July 2012.The disseminated nickel sulphide and alloy mineralization is hosted within the serpentinized dunite subzone of the Dumont Sill; a differentiated, pervasively serpentinized, ultramafic sill of komatitic affinity. Pentlandite, heazlewoodite and awaruite are the dominant nickel-bearing, metallic phases and can be recovered by conventional methods (flotation, mag separation). Non-recoverable nickel is also present within the silicate matrix of the serpentinized dunite and is locked in serpentine (Fe and Mg-rich variants) and minor olivine.A detailed mineralogical program including 1097 QEMSCAN® samples and 4300 electron microprobe points were undertaken to increase the understanding of the nickel deportment in the various recoverable and non-recoverable phases in a spatial context across the deposit. Eighty-three (83) metallurgical tests performed under a standard procedure have linked the mineralogy to metallurgical performance. This has allowed the creation and modelling of geometallurgical domains on a block by block basis to understand the recovery variation and metallurgical performance throughout the deposit. Understanding the spatial variability of Ni deportment in recoverable and non-recoverable phases through mineralogy is the key to understanding metallurgical performance thus, unlocking the value of the Dumont deposit and other large tonnage low grade ultramafic nickel deposits."

Jan 1, 2013

By Richard F. Hewlett

Engineers at the Bureau of Mines Denver Mining Research Center have been a research program investigating the theory and application of mine sampling. Part of this program is an investigation of the efficiency of sampling methods that involves development of sampling-method theory through simulating ore-deposit samples and assays, using - electronic digital computer. Theoretical developments are checked against actual ore-deposit sampling, assay, and production data by the commonly used polygonal and triangular methods of computing grade and tonnage of ore reserves. To speed the computing procedures, a program has been developed utilizing a medium-size digital computer for computing ore reserves by the polygonal method. This program calculates nine prismoids per minute at a total cost of $0.21 per prismoid. The complete program, written for an augmented IBM 650 computer, is described in detail; it can be used without change for computing ore reserves for a low-grade deposit. Modifications necessary to convert the program to compute ore reserves for virtually any other type of deposit or grouping of ore horizons also are given; however, the program is limited to using only vertical drill-hole data.

Jan 1, 1962

By B. R. Schneiders

"Atikokan is 200 km west of Thunder Bay and earned its mining fame from the discovery of the Steep Rock Iron Range in the late 1930s. Gold, however, was discovered in the Atikokan and Mine Centre areas in the late 1800s and eventually led to one of Ontario's first gold camps, and a total production of approximately 52,000 oz of gold and 174,000 oz of silver from 218,000 tons milled.The general geology of the area consists of Early Precambrian rocks of the Wabigoon and Quetico subprovinces, separated by the east-trending Quetico Fault. The Wabigoon Subprovince, to the north, consists of metavolcanics, minor metasediments and granitic batholiths. The Quetico Subprovince consists of metasediments and granitoids. Small ultramafic plutons occur throughout the metasediments.Within a 50-km radius of Atikokan, more than 50 gold occurrences, prospects and past producers have been discovered since the 18oos. The Atikokan Gold Study performed by the Ontario Geological Sur vey (Wilkinson, 1980, 1982) defined three types of gold mineralization in which gold is concentrated in quartz and quartz-carbonate veins:I) Metavolcanic-Hosted, Stratabound Type-associated with altered felsic fragmental units and chemical sedimentary rocks; possible gold mineralization source rocks. The mineralization is due to metamorphogenic (epigenetic) enrichment. Associated with dynamic metamorphism events and/or felsic intrusive events.2) Marmion Lake Batholith Type-occurs within the gneissic core of the batholith associated with north east-trending lineaments, representing faults or shear zones. Mineralized veins are related to several periods of deformation and shearing, suggesting that metamorphogenic veins were produced during dynamic metamorphism.3) Contact Zone Type -occurs in the contact zone rocks between gneissic batholiths and meta volcanic belts. Hydrothermal solutions produced during several deformational periods acted to leach and concentrate gold mineralization. Localized, discontinuous shear zones host the epigenetic (metamorphogenic) veins.Twenty-one properties in the area were mapped and sampled, and researched petrographically and geochemically. Geological data from the Atikokan Economic Geologist Program of the Ontario Geological Survey are used in discussing the types of mineralization, genetic models, and exploration targets and techiques."

Jan 1, 1983

By Kenneth Gavin, Weichao Li, Paul Doherty

"The lateral load capacity is one of the most important issues to be considered in designing piles to resist berthing loads, ship impact forces and for monopiles used in the offshore wind sector. A number of semi-empirical design approaches are available to calculate the ultimate soil resistance and assumed soil reaction profile along the piles’ embedded depth. In order to investigate the response of monopiles to lateral loading, a series of field experiments were conducted on instrumented steel pipe piles. Two lateral loading tests were performed on model piles with a diameter, D, of 340 mm and embedded depth, Lem, of 2.2 m, giving a Lem/D ratio similar to those adopted in the offshore wind sector. The piles were driven into dense sand at the University College Dublin geotechnical test bed site in Ireland. 10 pairs of strain gauges were installed on each model pile along the embedded depth at 10 levels to capture the load transfer and bending moment within the piles. The deflection and rotation at the model pile head were measured by Linear Variable Differential Transformer (LVDT) and inclinometers. The tests results were used to perform a detailed evaluation of current design methods. In the final section, discussion on the determination of the ultimate lateral load capacity for monopile design was conducted. IntroductionA pile’s lateral load capacity is determined, for design purposes, by two conditions: 1) the ultimate lateral load, Fu, divided by an appropriate safety factor; and 2) the load according to the maximum lateral deflection that the support structures can sustain. In view of the first condition, design methods to calculate the ultimate load were developed for piles used in the offshore oil and gas sectors, which tend to be much more slender than monopiles used in the wind industry. The purpose of this study was to investigate whether these design methods provide reasonable estimates of ultimate capacity, for short rigid monopiles.The methods to determine the ultimate lateral load generally follow three steps: 1) determine the ultimate soil resistance, Pu, along the pile embedded depth; 2) adopt the most appropriate soil reaction profile, Pz, along the piles embedded depth when the pile subjected to the ultimate lateral load condition (four of the most popular ones are depicted in Figure. 1); and 3) ensure equilibrium of lateral forces (see Equation 1, symbols are listed at the end of the paper) acting on the pile and bending moments (see Equation 2) about a point in pile is employed to determine the ultimate lateral load."

Jan 1, 2015

By Jurij Karlovšek, Wolfgang Angerer, Vojtech Ernst Gall, Jacob Grasmick

The International Tunneling Association (ITA) Working Group (WG) 22 “Information Modelling in Tunneling” has developed a guideline for the implementation of Building Information Modeling (BIM) concepts for Bored Tunneling Projects. The guideline primarily covers the use of BIM during the conceptual and delivery phases of a project. It provides Owners with an introduction to BIM, an overview of the current capabilities of BIM, and a guide for implementation for a Bored Tunnel. The document will be officially published at the World Tunnel Congress (WTC) in Copenhagen in 2022. This paper describes the need for the guideline and provides a preview of its contents.

Dec 1, 2022

By R. C. Allen

ABOUT four years ago the writer proposed a revision of the correlation of the Huronian formations in Michigan, and noted the bearing of the question on the correlations of the Huronian rocks in Wisconsin and Minnesota.1 Dr. C. K. Leith opposed this revision and argued for the retention of the correlations of the United States Geological Survey, published in 1911,2 for which he and Dr. Van Hise were mainly responsible. As late as June, 1917, Harder and Johnson, following Leith, thought it "premature to change radically a correlation based on years of careful field work."3 The work of Wolff on the Mesabi and Cuyuna Ranges, of Hotchkiss on the Gogebic Range (unpublished), and of the writer and assistants on the Michigan ranges, together with data developed by exploratory and mining operations, has introduced so many pew facts not recognized in the scheme of the U. S. Geological Survey that the correlations of 1911 must be considered, in some important respects, obsolete. Indeed new data are accumulating so rapidly that any classification, which for the moment may seem best to explain the facts, is almost immediately modified or refined by further observations. The problem of Huronian correlations is difficult, but interesting and important. With the aid of fossils, stratigraphers of the post-Algonkian formations have been able to show that slight disconformities may separate strata of vastly different ages, and that within physically conformable strata may be concealed a hiatus of great magnitude. In the non-fossiliferous Huronian group, minor physical breaks in the strata are

Jan 9, 1919

By F. C. Blare

THE best method for the estimation of copper in ores and secondary products is that proposed by Dr. Steinbeck* for the award offered by the Mansfeld'schen Ober-Berg-und Hutten-Direction. It is based upon the decolorization of the blue ammonia solution of copper by potassic cyanide,† It is necessary for the accurate estimation of copper in arsenides that the arsenic be separated from the copper before the ammonia solution is made. The presence of a notable amount of arsenic renders the titration by potassic cyanide inaccurate, the end reaction being obscured by the appearance of a yellowish-green tint towards the end of the titration. The change of the color of the ammonia solution from blue to the tint caused by the presence of arsenic cannot be used for an end reaction, for the intensity and quick appearance of the latter-color depend upon the amount of arsenic present in the solution. In the analysis of speise, the method of separating the copper by an oxidizing and reducing treatment in the muffle, to volatilize the arsenic, gives poor results, and there may easily be some loss of the weighed sample. The separation of the precipitated sulphides of arsenic and copper by treating with sodic sulphide, gives good results, but the process is tedious. I have used the two following methods, which are simpler and more expeditious than those mentioned, with good results. * Fresenius, Zeitschrift Air Anal. Chemie., viii, 1. †First noted by Parkes in the Mining Journal for 1861.

Jan 1, 1881