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More than in any other way, the community judges the minerals industry by its environmental performance. Minerals Council of Australia web site www.minerals.org.au/media/code Time is overtaking us. What was good enough yesterday is not good enough today. What may be acceptable today wonÆt be tomorrow. So we need to leap forward. We need to begin to move towards sustainability. Dick Zandee, Managing Director, Placer Dome Asia Pacific The competition for access to exploration and mining opportunities is intense. So is competition for the best people, capital and community support. Poor environmental performance damages a companyÆs ability to attract these. Quite simply, good environmental management is good business. Hugh M Morgan AO,Chief Executive Officer,WMC Limited. Decisions made by private industry and international corporations are increasingly determining the fate of the environment. ...Nothing could be more shortsighted than for todayÆs conservationists to neglect cooperation with business and industry as a means of moving company philosophy and public accountability ahead in favour of the environment. Dr Claude Martin,Director General,WWF International The four quotes above well illustrate the challenges faced by companies and conservationists in attempting to achieve the societal goal of sustainable development. That this aspirational goal itself is far from clearly defined, although it has been widely accepted and endorsed by governments, business and civil society, exacerbates the challenges. Sustainable development has as its central thesis the integration of environmental, social and economic policy. Its attainment by business has been described John Elkington (1998) as the pursuit of the ætriple bottom lineÆ - the achievement of social and environmental targets, in addition to the traditional economic bottom line. It is self-evident that business is both competent and comfortable defining and measuring economic performance and reporting that performance to internal and external audiences. As long as information has been prepared according to the established standards of measurement and reporting of economic performance, all audiences can have confidence in its accuracy. Business does not enjoy the same competence and comfort with regard to social and environmental performance. This is no startling condemnation of business, any more than it is a criticism of governments, non-government organisations (NGOs) or academia. It is a statement of fact that the tools to allow for credible definition and reporting against the other two components of the ætriple bottom lineÆ have yet to be fully developed and are, therefore, far from being widely accepted. Crucial to achieving sustainability is the ability to measure progress toward the goal. The task is to develop means to define appropriate performance standards and to credibly measure and report company environmental and social performance against those standards.

Jan 1, 2000

By T. Egleston

I HAVE to announce with great regret that our distinguished honorary member, Louis Gruner, died in Paris in March last. The Institute, in his death, has lost one of the first as well as one of the greatest of its honorary members. I speak with great feeling, as he was both my instructor and my friend ; and I am sure that if he could hear what I am about to say of him, lie would object to it. Mr. Gruner's modesty was such as even to prevent, except in his own Corps, the thorough appreciation of his work in his own country. I think be mas better appreciated by those who are familiar with his labor in almost any other country than his own. A just man, a thorough scholar, a great investigator, he was so unselfish that almost the last act of his life, and the last letter he signed, only a few hours before his death, had for its ohject to render a service to one of his former pupils. I think no one who mas ever associated with him could forget, in the greatness of his learning, the sincere and earnest friend, mho was always ready to render a service, where such service could be rendered even at great inconvenience to limself. His own motto, "Sein, nieht schein;" that is, "Be, not appear to be," was singularly descriptive of his character; and, what is more than all, he was one of the most earnest Christian men with whom it has ever been mv. good fortune to be thrown in contact. There are few such men. He was one of the greatest metallurgists that Europe has ever produced; a man the more remarkable because, though known to most of us as a metallnrgist, some of the best work of his life was in the domain of geology to which he contributed very important researches and memoirs, which will remain permanently among the valuable additions to the geology of his own country. He was, at the same time that he was the greatest metallurgist in Europe, a brilliant chemist, a thorough geologist, a distinguished professor, and an expert, practical miner, whose advice and methods had only only to be known to be followed. Mr. Gruner was born in Smitzerland in 1809, and graduated from the Polytechnic School of Paris in 1530 and entered the School of Mines, from which he graduated with distinction in the Corps of Government Engineers of Mines at an early age, and was immedi-

Jan 1, 1884

IN order that you may be expert in every phase of this art of parting, I wish to caution you upon twelve points, all necessary, so that you may know beforehand what may happen to you and what provision you must make to obtain good results. Understand that the gain derived from this art lies in carrying out the work that you wish to do accurately and with profit, which means nothing other than working with certainty and seeing that there is no loss of gold or silver [69v] or substance of anything that is valuable in itself. For, since everything lost is silver or gold, it is valuable however little. it may be, and many little things obviously make one large one; for gain increases gain, and loss, loss. Therefore, you will have as your first task to seek to have the materials that you are to use for making the aqua fortis of as perfect a nature as possible. I tell you this because the saltpeter is often weaker and of worse quality than the alum. For this reason it is necessary to make an effort to have it not only well refined and free from earthiness but also of a nature as powerful as pig [dung] saltpeter, the color of which tends strongly toward yellow. In order to work better, you also refine this again before you put it to use, as I shall tell you in its place. Likewise, see if you can get alum of the red kind that comes from the Levant or from Cartagena, for it costs less and is more powerful. Furthermore; see that you have a good number of well-formed cucurbits of properly purified glass not too large and of, equal content and size. Above all, see that they contain, no indentations, bubbles, folds, or scratches, especially, in the, body or in the bottom, because they break easily and the nature and great force of the acid pierces them by eating away, and makes a little hole. For this reason, cucurbits. are always divided into four grades; one is taken for making aqua fortis, another for drying the waters when they are laden with silver, the third for recovering the acids from the separations, and the fourth are either rejected as useless or dangerous, or are saved for recovering the whites or for some other service. Whoever wishes to practice this art well should remember to keep a large supply of cucurbits, receivers, and alembics. The third is the precaution which one must take in luting them; first, to

Jan 1, 1942

By T. Sterry Hunt

It is now five years since I called the attention of the Institute to the industrial importance of the coal and the iron ores of the Hocking Valley in Southeastern Ohio, and in a pamphlet on the region published soon after, in 1874, endeavored to resume the principal facts then known respecting it, including the observations of the geological survey of Ohio, made and published up to the time by Professors Andrews and Wormley, together with an estimate of the probable future of the region, and its relations to the coal and iron markets of the country. Since that time the labors of the Geological Survey have included a further study of the coal by Prof. Edward Orton, the results of which will be awaited with much interest. I may say from my knowledge of them, that while confirming the general conclusions of his predecessors, he has been enabled to add much to our knowledge as regards the correlation of the various members in different parts of the coal-field; and to show more clearly the positions and the importance of the ore-beds in the Hocking Valley region. The only ore mined in that vicinity previous to 1874, was below what is called the Great Vein or No. VI coal, and to the west of what is known as the Hocking Valley coal-field, and although experiments in a few furnaces in the State had shown that this coal could be used with advantage in iron-smelting there was not a single blast furnace within the field. My observations at that time, however, impressed me with the abundance of iron ore, not only below but above this important coal seam, and I then ventured to express the opinion that this region, from its cheap and easily mined smelting-coal, its native ores and limestones, and its geographical position and relations to the great markets of the West, and to the supply of rich iron-ores from Lake Superior, was destined at no distant time to become a great metallurgical centre, where iron could be made more cheaply than at any other equally accessible point in the country. The object of the present communication is to report progress, and to state how far my observations made in the region 1st month have justified the predictions of 1874. The five years which have elapsed have been, as all know, most unfavorable to the iron trade, and especially to new enterprises in untried regions, yet they have not passed without important industrial developments in the Hocking Valley, where not less than thirteen blast furnaces have been erected

Jan 1, 1879

Of all of the processes in the mining cycle, blasting has the greatest impact on the efficiency of both mining itself and the initial stages of ore processing. The cost of blasting can be readily accounted for, but the true benefits of an effective blasting operation are seldom measured or reported. This means that blasting is seldom optimised in terms of its overall economic impact on an operation. Blasting operations have evolved according to the environment provided by mine management. Most operations seek to minimise the unit cost of each component process (overburden removal, blasting, excavation and transport, crushing or grinding) without recognising the impact that blasting performance has on subsequent activities. The creation of æcost centresÆ or æmanagement unitsÆ that isolate blasting from its downstream impacts reinforce this trend. Modern blasting technology is regarded as sophisticated by virtue of the mechanical design of the drills, the chemistry of the explosives and the flexibility and reliability of modern blast initiation systems. However, blast performance is controlled by the nature of the rock mass and there is generally an inadequate appreciation of how blast designs should be tailored to suit different rock mass conditions or to meet different blasting objectives. Most operations utilise a limited suite of standard designs without routinely tailoring designs to suit the actual conditions at hand or the objectives of each blast. Mining operations would benefit from tackling the following specific challenges:What is the appropriate target performance for blasting operations to generate the maximum economic benefit for the operation as a whole? How should designs be configured to suit the changing rock mass conditions and operating constraints? What compromise (if any) should be allowed from the ideal to assist conflicting scheduling or other operational requirements? How can blast performance be measured and reported to provide appropriate guidance to future operations? These challenges can be tackled through the process of æblast engineeringÆ. This paper discusses the potential impact of blasting performance on the economics of mining operations and the author argues that very considerable benefits over and above those currently being achieved could be realised by improving the routine engineering of mine blasts. The paper then explores how the industryÆs failure to recognise the economic importance of blasting has resulted in the engineering of blasting operations receiving less management and technical support than is appropriate. Finally, a simple approach to the engineering of routine blasting operations is described as an example of how these challenges can be tackled.

Jan 1, 1999

By L. J. Klinkenberg

It is pointed out that the current concept of pore size distribution is not unequivocally defined and that different methods aiming at a determination of such a distribution therefore do not lead to the same results. A pore size distribution should not be based on the idea that a core should, under all circumstances, behave as a bundle of straight non-interconnected capillaries of the same pore size distribution. This is illustrated by calculations and experiments on the displacement of miscible liquids. INTRODUCTION The introduction of the concept of pore size distribution has been an attempt to characterize the intricate geometry of the flow channels in porous media. As pores in a porous medium are interconnected it is impossible to describe exactly what is meant by a "pore" and, therefore, the term pore size distribution requires further amplification. In the visual method for the determination of pore size distribution "the pore" is considered to be the hole between the grains as observed on thin sections or on a polished surface of the rock under a microscope. In all other presently known methods,1,2 a displacement process is studied and it is ascertained what as- semblaae of straight cylindrical capillaries would show the same behavior. The distribution of the capillary diameters of this assemblage is said to represent the size distribution of the pores of the actual porous medium. From the foregoing it is already apparent that it is useless to try to decide which process or which method of investigation leads to a "correct" pore size distribution. To illustrate this further a displacement process in which a fluid is displaced by another miscible with it will be discussed and the results will be interpreted in terms of a pore size distribution. DISPLACEMENT EXPERIMENTS WITH MISCIBLE LIQUIDS OF NEARLY IDENTICAL VISCOSITY AND DENSITY Interpretation in the Form of a Pore Size Distribution If distilled water is displaced from a homogeneous unconsolidated sand pack by, for instance, a dilute solution of NaCI, the breakthrough recovery i.e., the amount of distilled water produced at the moment the first trace of NaCl can be detected in the effluent water, is between 95 and 100 per cent of the pore volume of the pack. This result can be understood by following in imagination the course of one particle of the liquid. Imagine a length, ?l, at the end of which a liquid particle has an independent chance of a renewed choice of pores of different diameters. In other words, the particle has a choice of traveling time, at, for any length ?l; instead

Jan 1, 1958

By Randy Ynchausti

ERIC GUTIERREZ, Knowledgescape: Our next speaker is Randy Ynchausti. He's the director of development, Knowledgescape systems division, of EIMCO Process Equip- ment Company. The title of Randy's talk is "An Expert Control System for Phosphate Beneficiation." RANDY YNCHAUSTI: System integration. How does the systems integrator survive when caught between plant engineers, plant management, and third-party engineering firms, and stay within the budget of the corporate goals? I'm not sure that anyone knows how to do all of that on one project. Results are critical when we talk about how systems integrators work with operating people, how the operating people want systems integrators to work with them, and how both groups work together so that at the end of a project, you have been provided with solutions that meet your needs and solve your problems at a fair price. How does the integrator's role change when working with different types of professionals, such as plant managers, plant engineers, engineering firms, or other system integrators? Finally, what is the dynamics of people working with machines and providing services and solving needs? The average number of employees per pound of copper processed has decreased significantly during the past 15 years. I would dare to generalize and say that the average number of employees per whatever unit of measure we have in whatever industry we work in has decreased over the last 15 years. From a system integrator's perspective, there are some clients who lack a bit of internal expertise as corporate downsizing occurs, and that's one reason why we go out to system integrators or third-party vendors and buy things from them to solve our problems. Downsizing really amounts to savings, but more than that, I think Brian expressed this and I agree with him, it also amounts to a cost. Unfortunately, most of us count the savings and none of us count the cost in that approach. It's easy to count the savings, which is one reason why we count it so quickly. Maybe that also accounts for why we set our pencils down so quickly after we get that dollar value. Maybe we should pick that pencil up every once in awhile and refigure the expense, the cost to us, and determine what we're going to pay during the next year or two or three in losing that expense, or that staff. A broad experience base accumulated over projects at various plants helps system integrators to provide services to clients. This experience enables the system integrator to

Jan 1, 1998

By E. C. Harder

J. T. SINGEWALD, JR., Baltimore, Md.-I might say a word further in regard to the Miguel-Burnier district. I am sorry Mr. Harder is not here. I had hoped to be able to ask him a few questions in regard to some of the features of those deposits. This Miguel-Burnier district is the other district that I referred to that lies in the State of Minas Geraes. The interpretation that Mr. Harder gives to, these deposits is the same as that given by Harder' and Chamberlin in a previous paper, and that is that they consist of lenticular deposits of sedimentary origin in a series of rocks that also include lenses of limestone, but they seem to think that the manganese ores occur at a definite horizon and at a horizon different from the limestone. We found that the manganese ores occur at several horizons, as also do the limestone lenses, and the limestone masses are of the same shape as the manganese orebodies, so that our own feeling was that these manganese ores simply represent concentrations within the zone of oxidation formed as. a result of decomposition and replacement of this limestone. To the east of Miguel-Burnier there is a big bend in the railroad which cuts through, at right angles to the strike, this series of rocks. Here is shown very well both the local character of the limestone lenses and the local character of the manganese lenses in that, though the distance across the bend is only a couple of hundred yards, the limestone and. ,manganese lenses do not match up at all, and it also shows plainly that both occur at more than one horizon.. Consequently there is no reason why the manganese ore could not represent alterations of this limestone. The mine workings do not as yet give very definite information on this point in that they are all comparatively shallow and within what would be the zone of oxidation so that what they will grade into below that depth, we do not know. On the other hand, the character of the ore suggests that it may, represent such -a product in the zone of oxidation in that it tends to be quite earthy; whereas, if the manganese had been there originally as such it would have undergone the same metamorphism that the other rocks have undergone and one would have expected that it would have been converted into a hard manganese ore that would today stand out pretty much as do the iron ores of that same region and not have the soft, earthy texture which is a prevailing characteristic.

Jan 4, 1917

By George J. Tamaro

The design and construction of foundations in the New York City area are usually dictated by the widely varying geologic conditions encountered in the five boroughs, particularly along the spine of Manhattan Island. Rock extends well above sea level at the northern reaches and falls to depths in excess of 250 m at the barrier islands at the southern extremities. These highly variable geologic conditions, significantly affected by glacial activity, dictate different design and construction approaches throughout the five boroughs of New York City. Extensive rock removal is required at the north while long piling is dictated in the south. Similar changes can occur within a project site on Manhattan Island. This paper will describe these conditions in general, will identify the various solutions used to solve these problems and will summarize various foundation types used in the New York City area.

Jan 1, 2000

By S. F. Mauser

This report describes the study of factors which affect medium voltage (661 - 1000 volts) trailing cable splices used in underground coal mines. Improvements in quality, dependability, and design of splice kits and shop splices are presented in the study results and recommended guidelines and regulations. Recommended research programs are included which describe approaches for development of the recommended guidelines and regulations for medium voltage trailing cable splices. The basis for the conclusions and recommendations presented in this report is included in three appendices which describe a survey, splice examination, and general requirements development prepared during the progress of this study.

Jan 1, 1977

By S. L. Windes

This report presents a tabulation of the physical and petrographic properties of Over 100 rock types from operating mines or mineral-investigation projects. The physical properties include the following: Apparent specific gravity Apparent porosity Compressive strength Flexural strength, (modulus of, rupture) Impact toughness Abrasive hardness Scleroscope hardness Modulus of elasticity (Young's modulus) Modulus of rigidity Specific damping capacity Longitudinal bar velocity

Jan 1, 1949

By Francis W. Gray

Introduction Extensive undersea coal-mining has developed on both the east and west coasts of Canada, and at this time some four million tons, or 25 per cent of the total output of Canadian coal, representing a pit-mouth value of $14,000,000 per annum, is coming from coal seams lying under the sea. Of the coal now being mined in Nova Scotia, 55 per cent comes from under the sea, and this proportion is likely to increase. The Province of Nova Scotia is at this date receiving in royalties paid upon coal ?removed from undersea areas a sum exceeding $400,000 per annum. The subject is, therefore, one of special interest to the Mining Society of Nova Scotia and the Canadian Institute of Mining & Metallurgy, and while this paper will deal chiefly with undersea coal-mining in Nova Scotia, an attempt has been made to summarize the development of mining practice in the winning of undersea coal in other parts of the world, with the hope that such a recital may assist in the assessment of local problems. The connection between the mining of coal under the sea and an insular or maritime geography is obvious in regard to Great Britain, Japan, Vancouver Island, Australia, and Cape Breton Island, and also in regard to the curious conformation of Chile; the tendency towards growth of a mercantile marine and naval eminence is equally obvious where coal is mined at tidewater. But, there is the further and less favourable significance that the mining of coal under the sea is associated with poverty rather than with abundance of coal reserves.

Jan 1, 1927

By D. A. Paice

Direct current electrical systems are used in most coal mines primarily to power the main haulage trains and secondarily to feed other equipment and passageway lighting. Electrical power is supplied from rotary machines or static rectifier equipment and is distributed through the mine by open trolley wires and feeder cables. The rails of the haulageway are used as a current return path. This exposed power distribution system is very vulnerable to conditions which lead to undesired leakage currents and short circuits and, consequently, the possibility of fires or other hazards to personnel. Present techniques and equipment have been utilized in so far as practical to improve the safety of the dc electrical system; however, there still appears a need for further improvement. Because of this need, this program was sponsored by the Bureau of Mines to investigate two specific technical areas related to improvement of dc electrical system safety. One area included the determination of the characteristics of mine electrical systems and their protection requirements and the verification of the adequacy of available protective devices for mine service. Despite the widespread application of industrial protective equipment in mines, there was little detailed technical information available related specifically to the performance of this equipment in service. Our task was not only to develop useful information regarding mine system protection, but also to define and verify the adequacy of the protective devices available. The second area of investigation called for development of a practical technique for detecting low level electrical fault or leakage currents. Conventional protective devices

Jan 1, 2012

By S. H. Lorain

This paper briefly describes the principal known commercial and near commercial deposits of gold-bearing gravel end the principal placer mining operations of Idaho County, Idaho. It is one of a series of similar papers on western mining districts. The data used in writing this paper were gathered during the summer of 1937. Information concerning gold-bearing gravels was obtained from prospectors and operators, while operators supplied most of the data on mining operations. No attempt was made actually to test the gravels. The principal object of the examination was to indicate placer areas worthy of further investigation by prospective operators.

Jan 1, 1938

By G. Stecklein

This report summarizes the results of research into the areas of the fragmentation and entrainment of Airborne Respirable Dust (ARD). The objectives of this program were four-fold: first, to review the present state of knowledge regarding ARD; second, to expand this state of knowledge through the identification of hypothetical microscopic mechanisms by which the coal is fragmented and the dust becomes entrained; third, to specify the informational requirements to verify or nullify these hypotheses; and fourth, to relate experimental techniques that will produce that required information. Additionally, insights are provided regarding potential methods of extraction and/or treatment which may reduce the concentration of ARD.

Jan 1, 1982

By Joel F. Flurnerfelt

Molten Al and Al alloys containing si, Mn, Ti, and y have been lanced with nitrogen-bearing gases. These lancing experiments provided the means for observing what phases form during exposure to nitrogen-bearing gases for finite periods of time, <2 minutes, at high temperatures, >1290oC. The experiments were conducted in sn induction heated drop tube furnace apparatus. The overall premise of these experiments was to select those Al alloys and gas compositions that show promise of forming secondary dispersoid phases, particularly AIN, in the Al matrix. The alloys selected will be atomized using gas atomization reaction synthesis (GARS) using the most favorable conditions. In this case, the chosen Al alloy will be atomized with a nitrogen-bearing gas, such that the Al and gaseous nitrogen species react to form a dispersoid phase within each powder particle. The powder particles that result from this "aggressive" GARS-process would be essentially Al metal-matrix composites within a uniform distribution of dispersoids. To date, only high-purity Al has been atomized using a mild GARS reaction. This work is funded by the Materials Science Division of DOE-BES under contract number W-7405-Eng-82.

Jan 1, 1996

By H. E. Frimmel

Abstract - Most of the gold in the Late Archean Witwatersrand Basin is of detrital origin but, in its present form, it is metamorphosed. The only relict detrital features preserved are the morpho­logical characteristics of some placer gold particles. Regional burial metamorphism in the shallower and deeper levels of the Witwatersrand Supergroup reached temperatures around 300°C and 350°C at pressures between 2 kbar and 3 kbar, respectively , estimated from phase relations, chlorite-chloritoid exchange thermometry and chlorite thermometry . Metamorphism of the gold involved compositional homogenization of individual gold particles and partial recrystallization. Various infiltration events caused the partial mobilization of the gold at slightly lower temperatures, between 240°C and 300°C. These infiltrations can be related to crustal extension during the deposition of massive carbonate sequences of the Transvaal Supergroup (around 2.5 Ga), and later to the emplacement of the Bushveld Complex, and to the Vredefort event around 2.0 Ga ago. The mobility of the gold was dependent on the sulfur fugacity prevailing in a particular horizon which, in turn, was deter­ mined by the amount of pyrite (and other sulfides) present in that horizon. With the sulfur fugacity being controlled by stratigraphy, low fluid:rock ratios in a pyrite-rich horizon were most conducive for the mobilization of the gold. Thus, long-range gold mobilization in the Witwatersrand Basin can be expected to be the exception rather than the rule.

Jan 1, 1994

By C. Jay Hodgson

Hydrothermal systems form on land where and when an impermeable cap-rock unit ( either natural or self-sealed) , a permeable aquifer. and permeable discharge and recharge channels (cross-stratal permeability) develop in an anomalously hot part of the crust. A consideration of the relationship between magmatic and tectonic events in volcanically active areas indicates these conditions arise during: (1) the resurgent doming stage of the resurgent caldera cycle; (2) following movement on the bounding faults of tilted fault blocks ; and (3) as a result of hydrothermal boring associated with the intrusion of major sills. On the assumption that the submarine hydrothermal systems which deposit volcanogenic massive sulphide ores are comparable to subaerial hydrothermal systems, it is suggested that: (1) the horizon of mineralization corresponds to the time period when conditions favour the development of hydrothermal systems, as outlined above; (2) exploration for Cu-rich Cu-Zn-Pb or Cu-Zn ores should be directed to paletopographically high areas near discharge conduits , whereas exploration for Cu-poor ZnPb ores should concentrate on paleotopographically low areas down slope from conduits; (3) deposits with stringer zones lying above normally permeable units may be underlain by regionally extensive weakly mineralized and altered zones (self-seal caps) ; (4.) in the absence of a self -sealed cap, the ore horizon may be underlain by a naturally impermeable unit (e .g. a fine clastic sediment) ; (5) the condition of cross-stratal permeability may be evidenced by features such as dykes. alignment of vari ous magmatic and hydrothermal phenomena, abrupt thickness changes in stratiform units indicative of ponding against syn-volcanic faults, and fault-scarp slump deposits; (6) the condition of high heat flow may be evidenced by near-surface magmatism and steep thermal gradients preserved in metamorphic mineral assemblages.

Jan 1, 1977

By R. G. Robins

Metal separations based on the selective precipitation of phosphates have a potential application in many hydrometallurgical processes. This paper reviews the literature on the solubility of a number of both divalent and trivalent metal phosphates and presents the result of some additional experimental measurements. The systems examined have been modelled to obtain free energy of formation data for the various species. Computer generated solubility diagrams which are described can be useful in predicting a variety of metal separations.

Jan 1, 1991

By J. Chelsey Dawson

In presenting a thesis on this subject it is advisable to explain a few of the reasons for its seeming incompleteness. World progress has brought us to a position where approximations are not only to be condoned, but regarded as absolute essentials. Production in anticipation of demand is always accompanied by mistakes on the part of the producers. Only through trial and sometimes erring hypotheses may there be evolved the true course and theory upon which the steady triumphant march of world-wide industry depends. The average person likes to have everything placed ?before him in a clear and convincing manner. It is the impossibility of doing this which, in many cases, arises to confound the writer on shales. All that one can do is to present, as lucidly as possible, the known hypotheses&apos; and theories on the subject and leave the reader to study and work out the truth for himself. Many theories have been advanced on the origin of oil-shales ; some may be correct in certain instances and not in others; however, the writer will attempt no decision as to which are and which are not correct, but .will merely point out the relative merits of each. The figures given for reserves of oil and shale in different countries are only approximations and give but a rough idea of the true conditions.

Jan 1, 1925