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By E. L. Ickes

DURing the summer and winter of 1918 eleven standard rigs were erected in the United Kingdom to test the petroleum prospects of- ten structures, eight of which were in England and two in Scotland. By the fall of 1921 ten of the wells were completed; the remaining one, the D'Arcy in Scotland, was stopped some months later. The tests were deep ones, five of the wells being 4000 ft. or more, the rest varying in depth between 1810 and 3918 ft. The total footage drilled was 40,047 ft. The holes were put down with standard or cable tools purchased in the United States (except the boilers). The larger sizes of casing, 10-in. and above, were also from America, while the smaller sizes were secured in Scotland. The Hardstoft well in England found a small production of high-grade oil and the D'Arcy well also encountered what is reported as a favorable showing at a depth of 1810 ft. The Werrington and West Calder wells had to be abandoned on account of drilling difficulties. The Apedale well encountered great thicknesses of ash in the Carboniferous and had to be abandoned on account of depth. The results might be summarized by saying that of the ten structures drilled upon, two yielded encouraging showings; three cannot be considered as having been adequately tested; and five produced dry holes, although in some of these small oil showings and gas were met. The total cost of the work amounted to about half a million pounds sterling, which sum includes the cost of all equipment, subsequently sold by the government. The work, under the superintendence of V. L. Conaghan, took place for the most part in the period immediately following the war—a period of high prices, labor and transportation difficulties, and unsettled conditions generally; factors tending to retard the work and affect the costs. The writer, as a member of the staff of S. Pearson & Son, Ltd., had charge of the administration of the work during its later stages and

Jan 1, 1924

By E. W. Shaw

Continued discussion of the paper of Roswell H. JOHNSON, presented at the New York meeting, February, 1915, and printed in Bulletin No. 98, February, 1915, pp. 221 to 226. See also Bulletin No. 101, May, 1915, pp. 1157 to 1162. E. W. SHAW, Washington, D. C. (communication to the Secretary+). -With the word petrology-literally the science of rocks-being used primarily for igneous rocks, and with geophysics coming to mean the study of lavas and the rocks into which they solidify, contributions to the knowledge of the physical chemistry of sedimentary rocks, even though only ideas which may be used as working hypotheses, become most welcome. The forces which control the formation and subsequent history of the stratified portions of the earth's crust are so little known that no one has yet been able to settle finally the questions as to whether petroleum is of organic or inorganic origin; whether it originated far from its present position, or nearby. Yet both the chemical and physical problems of the rocks in which oil occurs seem to be more simple than those of the igneous rocks. The oil-bearing rocks of western Pennsylvania, for example, have in all probability never been subjected to a pressure exceeding 3,000 or 4,000 lb. to the square inch, nor to a temperature higher than 100° or 200° C. These pressures are considerably below the crushing strength of rocks, and the temperature far below their melting point. The igneous rocks,, on the other hand, have been affected by enormous pressures and very high temperatures and yet steady progress is being made in reproducing in the laboratory the conditions of their formation and subsequent modification within the earth. The solution of the sedimentary-rock problems would seem to be fully as important as those of igneous rocks, and yet we must content ourselves with reasoning backward and our inferences as to what has happened are oftentimes little more than guesses.1 One of the fundamental problems is the origin of the salt water in oil fields. Is the salt water fossil sea water; has it been formed by the solution o-f salts of various kinds from distinct beds, from disseminated par-ticles, and from the weathering of suitable grains in the rock; or is it of deep-seated origin? Its general resemblance to sea water points to the first, but the principles held by some concerning the free circulation of water throughout the earth's crust, and certain peculiarities of composition indicated by the few analyses available, seem out of harmony with such an explanation.

Jan 7, 1915

By O. P. Arora, J. B. Darby, Paul A. Beck

LAVES and Wallbaum' reported that the phases occurring at the compositions TiFe, TiRu, and TiOs, which are stable over a wide range of temperatures and are separated from neighboring phases by wide two phase fields, have a CsC1-type ordered structure. For TiRu and TiOs, this was recently confirmed by C. B. Jordan.2 Recent results of Greenfield and Beck3 show that solid solutions with ruthenium of the body-centered-cubic elements vanadium and tantalum (and presumably also of colum-bium) in group Va of the periodic table undergo CsC1-type ordering. Although detailed phase diagrams for these systems are not yet available, it would appear that these ordered structures are separated from the neighboring body-centered-cubic solid solutions by relatively narrow two phase fields.

Jan 1, 1957

By John D. Wiebmer

First, a definition of a small scale miner is in order. The US Bureau of Mines classifies him as one who produces 360 t/d (400 stpd) of ore or less. In Canada, he would be refered to as a "junior company." Mexico identifies the small scale miner as one whose gross income from operations is less than $880,000 per year. A small surface mine in India employs less than 400 people, and a small underground mine employs less than 150. Peru considers a small scale miner one who produces less than 54 000 t/y (60,000 stpy) of ore. Obviously, the term is relative. What may be a small mine in one country is a medium or large mine in another. This lack of agreement is understandable since small scale mining does not often cross national boundaries. Rather, its effects are felt at the regional and local levels within each nation. Its importance doesn't lie with any huge contribution to the GNP or balance of trade. Instead, its value is as a local employer and as a frontrunner in geologic exploration.

Jan 2, 1979

By Cadwallader Evans

THE American Institute of Mining Engineers was organized in the anthracite region of Pennsylvania by men who were primarily interested in anthracite. Its first meeting, at Wilkes-Barre, Pa., in the Northern Anthracite field, on May 16, 1871, resulted from a call sent out by three outstanding men of the anthracite .industry: Eckley B. Coxe, R. P. Rothwell, and Martin Coryell. The best known of these was Eckley B. Coxe, who was the manager of large hold¬ings operated by him and his family,. and who is remembered as the inventor of a special grate for burning very fine anthracite, known as the Coxe traveling grate, which is still very widely used. R. P. Rothwell was a well-known consulting engineer of the region, as was Martin Coryell, who was associated with another well-known anthracite family, the Pardees. There is no record of the discussions that resulted in this initial meeting, but it is safe to assume that the formation of the Institute was largely influenced, through appreciation by the founders, of the necessity for a free exchange of information covering the whole of the mining industry. One of the rules adopted at the first meeting was:

Jan 1, 1947

By H. W. Hockin, D. r. Brandt, R. H. Walsh, P. L. Dietz, P. R. Girardot

New Jersey, Florida, and Canadian ilmenites were reduced with hydrogen or coke under various experimental conditions and the phase changes occurring in the ilmenite upon reduction have been studied by microscopic examination of polished sections and by X-ray diffraction. The products formed were dependent upon the type of ilmenite, temperature, time and reducing agent. Of the reducing agents, hydrogen was the more effective at lower temperatures. 1 HE possible utilization of ilmenite as a source of both iron and titanium has resulted in the development of a number of methods for the separation of the iron and titanium content. Slagging processes as currently used in Canada are typical of such methods. Somewhat less attention has been given industrially to the reduction of the iron content at less than the slagging temperature. Although references maybe found to such work, in general only one type of ilmenite, either natural or synthetic, has been studied by each author. We have attempted to draw some relationship between the results of experimental reduction and the type of deposit from which the ilmenite was derived, as evidenced by phases occurring in the ores and in the reduction products. Ilmenite ores having from 27 to 61 pct titanium dioxide were included in this study and in each case reduction was carried out at such temperatures that only limited coalescence of the particulate iron product occurred within the ilmenite grains. The history of the individual ilmenite samples and the temperature of reduction were found to determine the occurrence of various phases and the mode of distribution of the iron. REVIEW OF EARLIER WORK ON REDUCTION One of the earliest references to the reduction of ilmenite at less than the slagging temperature was made in 1917.' The metallic iron produced was_____ leached out by the action of dilute sulfuric or hydrochloric acid, to leave a product high in titanium dioxide. Subsequent to this, numerous patents2-'? and other references13"21 have appeared concerning reduction of ilmenite by carbon, hydrogen, carbon monoxide, methane, coal gas, water gas, or the like in the absence of fluxing agents. Mineragraphic examinations were not reported, and in the main, the only examinations made were chemical analyses. However, in two cases3,13, titanium suboxides were reported in the products and in one case2' rutile was reported, in addition to metallic iron. Both were identified by X-ray diffraction. While reductions in the absence of fluxing agents were generally followed by either a wet or dry chemical process for removal of the metallic iron, a Canadian source17 reported removal of the metallic iron by magnetic separation. By the addition of fluxing agents during reduction, the metallic iron has been coalesced into "pearls." Each reference to such a process23-28 has shown that the coalesced iron could be removed by magnetic or gravity means after the product was crushed. In the absence of fluxes, the coalescence did not generally occur. The major part of the present study has been limited to reductions without fluxing agents in order to determine the primary reactions of naturally occurring ilmenites. Titaniferous iron ores have also been studied,29-33 17, l9 their reduction having been used as the basis of a commercial process for beneficiation of such ores in Norway29 and more recently considered in the United States34,35. The ease of reduction of titaniferous iron ores relative to that of hematite or magnetite has been referred to,33 with the conclusion that the more

Jan 1, 1961

By Joseph Lindmayer, Karl M. Busen

If silicon is in contact with silicon oxide, a heterojunction is formed which induces an inversion layer ("channel"). Influences of impurities and structural parameters on the channel are discussed. There seems to be no relation between surface damage in silicon and the channel. Phosphorz~s doping of the silicon oxide has no pronounced effect on the channel. Channels which were well above the range predicted by the heterojunction model were related to the action of H* at the silicon/silicon oxide interface. Channels which were well below tlze range predicted by the heterojunc-tion model were related to a transition region in the oxide adjacent to the interface. In support of the assumed transition region and the H+ are the ex-periments described on the paper. Furthermore, the concept of metastable OH groups in silzca, known from other publications, has been used to explain certain channel characteristics by the formation and the accommodation of hydrogen in the silicon oxide. THE electrical characteristics of a semiconductor device in many cases are influenced by the conditions of its surface. Because these conditions often are changing with temperature, time, ambient, or other parameters, numerous attempts have been undertaken to stabilize them by suitable processes. Several years ago Atallal studied the silicon/silicon dioxide interface and since then increasing attention has been given to the silicon dioxide as a means to stabilize silicon surfaces. This led to the evolution of the planar silicon devices where oxide layers are used to protect places at which the junctions are intersecting the surface. The formation of the oxide layers on silicon can be carried out by a variety of processes: high-temperature thermal oxidation (exposing the silicon surface to oxidizing agents such as 02, HzO, COz), evaporation of SiOz, or anodic oxidation of silicon. Originally the oxides were considered able to "passivate" the silicon surface and it was understood that they 1) protected the surface against any influence from the ambient and 2) stabilized surface conditions which were necessary for proper device performance. It soon was realized that the second quality was not always obtainable: Atalla and Tannenbaum showed that, in the process of forming a layer on doped silicon by thermal oxida- tion, electrically active impurities in the silicon near the interface are redistributed, thus giving rise eventually to the formation of unwanted charge distributions. The degradation of planar junctions during reoxidation of silicon was observed by Barson et a. Surface studies with silicon planar junction structures indicated that the breakdown voltage depended on the kind of procedure which was applied during or after oxidation.*" Yamin and worthinge report on charge storage and dielectric properties of SiOz films at elevated temperatures. Another influential parameter on the silicon surface is discussed by Lindmayer and usen,' namely the appearance of a surface potential on silicon as a consequence of the heterojunction formed by the silicon/silicon oxide interface. In the present paper the influence of impurities and structural parameters in silicon oxide in connection with the heterojunction is a particular object of our investigations. I) EXPERIMENTAL The material used was 10 ohm-cm p-type silicon slices with either damaged surfaces (mechanically lapped or polished) or damage-free surfaces (chemically polished). The majority of the slices were oxidized for 1 hr and 20 min at 1250°C in a steam + oxygen atmosphere generated by passing O2 through HzO at 90°C (wet oxygen). This led to oxide layers of about 9000 A. On some slices oxide layers were grown in pure oxygen (dry oxygen). By a photoresist process a set of 20 by 200 mil windows was then etched out from the oxide layer. The pattern of the windows is shown in Fig. 1. In a subsequent process n-type pockets with surface concentrations between 2 x 10" and 5 x 10" cm"3 were formed by phosphorus diffusion. This allowed ohmic contacts between the silicon surface and tungsten probes which for electrical measurements were placed into two adjoining windows and

Jan 1, 1965

By G. E. Anderson

THE Asientos-Tepezala district is in the north of the State of Aguascalientes, about 30 miles north of the city of Aguascalientes, the capital. The district is reached by a standard-gage railway on the west side through the junction, Rincon de Romos, which is on the main line of the National Railways of Mexico from El Paso to Aguascalientes. The terminal is Tepezala. On the east side a narrow gage connects Asientos with the junction, San Gil, on the main line, Asientos to San Luis Potosi. Tepezala on the west side of the Asientos hills is about 2 miles from Asientos on the east side. The area between the two mining centers is separated by a low subued divide which forms the central part of the hills. The district is in a group of isolated hills surrounded by characteristic bolson plains. The hills rise above the surrounding plains about 6500 to 10,000 ft.; the highest peak is Alta Mira. The two mining districts lie somewhat upon the flanks of the hills at about the same elevation, 7200 ft. The district is an old one and has been known since early in the 17th Century when the mines were worked by the Franciscan Monks. Their mining operations which were limited to the oxidized ore above the water level, consisted chiefly in extracting silver from the Santa Francisca vein. To judge from the old workings and the remains of surface plant, the operations were on a large scale. By modern mining operations since about 1900, the various mines of the district have been one of the principal sources of ore for the smelter located at Aguascalientes.

Jan 2, 1926

The plant, animal, and mineral arts and sciences are interrelated, interdependent, equally distinctive subject-matter fields. The artificial, erroneous, and popular idea that minerals occur in great storehouses in nature's treasure room to be removed at will at fabulous profits is about as correct as the assumption that the farmer's life is one of ease in which the crops spring miraculously from the ground. However, both of these fundament-a1 industries, mining and agriculture, have much in common. The extraction of minerals from the ground and the extraction of plants from the soil for immediate use, or conversion to meat, are fundamental activities and subject to many common economic laws. In other words, in many important basic concepts there is little difference between surface and subsurface crops. The farmer owner working the surface of the earth and the owner of a fraction of the oil or coal rights in the subsurface, from which a small yearly income is derived, are interested in the best management of the land for the mutual benefit of all concerned. Therefore, it is essential that in any planning or political action intended to create a new scheme of things, it should be remembered that one plan must fit all sources of primary wealth, whether coal or wheat, petroleum or milk, iron ore or beef.1 And what basic economic difference is there in the processing of a gallon of petroleum and a bushel of corn?

Jan 1, 1950

By D. L. Wood, J. H. Westbrook

The tensile behaviors of the CsCl structure compound AgMg are extensively documented in terms of strain, strain rate, temperature, composition, and metallurgical processing treatment. The observations lend themselves to presentation in terns of three regimes of deformation behavior; 1) low temperatures where deformation is primarily by slip; 2) intermediate temperatures where the deformation mode is also slip but with the detailed behavior dominated by dislocation interactions with solute atoms; 3) high temperatures where defomation is primarily by diffusion controlled processes. Of all the material groups of potential interest as high-temperature structural materials, the inter-metallics have been the least studied, particularly with respect to their mechanical behavior. Moreover, the application and processing of intermetallics for uses which exploit their often unique physical properties have been impeded by a lack of understanding of their mechanical properties. Previous work in this area* has been largely *For a recent review, see Westbrook.' exploratory, aimed on the one hand at the direct empirical development of materials of engineering utility and ,on the other at identification of the important parameters affecting the mechanical behavior of inter metallics. As a consequence, there has not been available, heretofore—for any inter-metallic—data, sufficient in extent or precision to provide an adequate phenomenological description of the effects of metallurgical variables on deformation behavior. Such documentation is prerequisite to intelligent application or processing design and is also necessary for testing present and future theoretical analyses of mechanical behavior. It was therefore an objective of the present investigation to document the deformation behavior of a simple ordered intermetallic over as wide a range as possible of all the usual metallurgical variables. The compound AgMg was chosen as the subject of this investigation because it met all of a group of desired criteria, namely: 1) congruent but moderate melting point; 2) simple crystal structure; 3) ordered structure persisting to the melting point; 4) broad solubilities for the component elements. The first and last criteria were expected to aid in the preparation of homogeneous single-phase specimens: the second and third to help simplify the

Jan 1, 1962

By George I. Smith

Jan 1, 1985

By J. E. Dinger, Ross Gunn

Faraday's Law of magnetic induction states that the e.m.f. acting around a closed circuit is equal to the time rate of change of flux through that circuit. If the closed circuit is a conducting medium, there will flow an electric current which is propor¬tional to the conductivity of the material and the time rate of change of the flux. Electrical currents so induced in a con¬ducting material are often referred to as eddy currents. Eddy currents are thus induced into a conducting material by (1) a time rate of change of the magnetic field through the material, by (2) a relative motion of the conducting material and a magnetic field, or by (3) a combination of (1) and (2). Because the magnitude of the induced eddy currents is dependent upon the resistance of the equivalent conducting path, these currents offer a method of detecting electrical discontinuities in a

Jan 1, 1945

By F. L. Kadey

The petrographic microscope is a well known tool in nonmetallic materials research. Its utility in the study of perlite is, therefore, not surprising. Valuable information has been derived on samples smaller than those needed by most other methods of analysis. Relatively little has been written about the petrographic analysis of perlite for two chief reasons: perlite is a material of relatively new commercial interest; and the independent prospector or expander, responsible for most studies, attacks the problem from an immediately practical viewpoint. Hence, petrographic studies of perlite have been limited to academic aspects. Rapid development of commercial interest in perlite has changed the situation. Mining and expanding companies now have effective research tools; and such instruments as the petrographic microscope have added materially to practical knowledge about this mineral. Petrographic techniques employed in the search for suitable deposits screen worthless samples rapidly and inexpensively compared with large-scale expanding tests. Hence, only samples of potential quality are selected for further testing. Field appearance of perlite reveals little about its true identity and practically nothing about its commercial significance. Consequently, any method that can be used to separate the "wheat from the chaff" is valuable. In addition to the conventional thin-section and immersion methods used in evaluation of crude perlite, petrographic microscope techniques have contributed to the study of expanded perlite. When apparently similar materials behave as differently in use as perlites, the internal structure of the individual particles becomes a subject of great interest. The purpose of this paper is to discuss some of the petrographic techniques used to characterize this material. WHAT IS PERLITE AND WHERE IS IT FOUND? Perlite was at first described as a glassy rhyolite possessing a pearl-like luster and exhibiting numerous concentric cracks resembling an onion skin appearance.' Fig. 1 is an illustration of perlite in this classical sense. Recently, its definition has taken on a commercial connotation: an acid volcanic containing 2 to 5% of combined water that, when heated rapidly to the softening point of the glass, coincident with the volatilization of the combined water, expands or "pops". Fig. 2, although hardly fitting the classical description given by Johannsen, is an excellent perlite in the commercial sense. It may occur as a breccia in rhyolite, (Fig. 3) and sometimes it is associated with obsidian nodules, as illustrated in Fig. 4. The term perlite includes the expanded product also. In the United States, perlitic rocks are restricted to the western part of the country. 2 Elsewhere in the northern hemisphere, European occurrences follow a belt beginning in Iceland and extending in a southeasterly direction through Scotland, County Antrim in Northern Ireland, and through the Massif Central of France, Germany, and Hungary; thence, into Italy and Sardinia, and through some of the Aegean Islands. A general oriental belt extends from Japan through Australia and New Zealand. Rhyolitic areas elsewhere in the world undoubtedly contain perlite.

Jan 1, 1963

By W. L., Yerkes

AN interesting study of the application of air-, conditioning to the problem of mine ventilation and cooling can be found on the Witwatersrand in South Africa. Here there are a large number of deep mines in a relatively small area. Due to the nature of the reef, many mines are working at a depth of 6000 ft. and some have gone down to 8000 and 9000 ft. below the surface. At such depths, even in a country geologically as old as Africa, the virgin rock temperature approaches 110°F. The flow of heat from the- rock to the ventilation air is tremendous though the shaft or drift may have been open to ventilation for some years. In addition, there is the heat produced by machinery, lights, and men at work and the heat of adiabatic compression of air introduced into the mine. The difference in atmosphere pressure between the collar of a shaft and a level 6000 ft. below is nearly 3lb. per sq. in., resulting in an increase in heat content of nearly four B.T.U. per pound of air delivered to the mine at surface. Further the exclusive use of wet mining to reduce the incidence of miner?s phthisis increases the latent- heat content of the air.

Jan 1, 1941

By T. A. Read, S. W. Kitchen, H. I. Fusfeld

At the present time most artillery cartridge cases are used only a single time. Since the process of reshaping a fired cartridge case so that it may be used again is much simpler and cheaper than the original manufacture of the case, it is clear that important savings could be effected if such re-formed cases were used in place of new cases. Extensive use of reconditioned cases has been hindered in the past, however, by the deterioration of the brass which may occur in the period of time between the first firing and the reconditioning of the cartridge cases. This deterioration sometimes results in a dangerously high incidence of firing splits in groups of reconditioned cartridge cases. It appears that the mechanism of the deterioration is the season cracking of the brass, for season cracks, of varying degrees of severity, may frequently be found in the cartridge cases after their return from the field. There are, of course, severe practical limitations to the extent to which fired cartridge cases can be protected from corrosion under battle conditions, particularly since the powder residue in the case is itself corrosive. The present paper describes a rapid method of testing the sidewalls of artillery cartridge cases for the presence of season cracks. This method has been developed specifically for use in connection with the reconditioning of fired cases, and makes it possible to carry out 100 per cent inspection. This new method of inspecting cartridge

Jan 1, 1945

By J. B. Newkirk, D. L. Martin, A. H. Geisler, R. Smoluchowski

A FUNDAMENTAL investigation of the mecha-nism of the ordering reaction and of the accompanying changes in properties has been undertaken, since an extensive study of this process could well contribute to the knowledge of phase transitions in alloys. Cobalt-platinum alloys were chosen for the study since they exhibit interesting and unusual permanent magnet properties.1,2. In addition, the ordering reaction in cobalt-platinum alloys is a convenient one to study experimentally because of the high maximum ordering temperature, the large difference in the X-ray scattering power of cobalt and platinum atoms, and the relative ease with which the alloys can be plastically worked into wire and strip. In the early stages of this study, it became apparent that the published phase diagrams&apos;, &apos; of the cobalt-platinum system contained questionable features, in the region of 40 to 60 atomic pct Co, which were considered in another publication by the authors.4 That portion of the research reported elsewhere on the equilibrium states of cobalt-platinum alloys does not confirm the presence of a previously reported, high temperature disordered tetragonal phase and a low temperature body-centered cubic phase. On the other hand, the structure of the ordered phase is face-centered tetragonal with an atomic distribution analogous to that of CuAu.4 This lattice forms from the disordered face-centered cubic phase in such an orientation that the <100> directions are parallel to the <100> direc-tions of the disordered phase. At compositions other than the ideal 50 atomic pct the ordered phase can exist in equilibrium at high temperatures with the disordered phase. A Widmanstatten pattern of plate-like particles of the ordered phase parallel to (110) planes of the disordered matrix is observed when an initially disordered alloy is held at these temperatures. The temperature range of the two-phase region has been determined for three alloys by X-ray diffraction analyses, microscopic examination, and electrical resistivity measurements, and these results are incorporated with some of those of Gebhardt and Köster in the revised phase diagram of fig. 1. The purpose of the investigation reported here was to examine the mechanism of ordering in co-balt-platinum alloys by X-ray diffraction and metal-

Jan 1, 1951

By Leon Merker

Flame fusion growth of strontium titanate crystals was undertaken to obtain large transparent crystals on which physical data could be gathered. The fact that strontium titanate is a cubic crystal and probably has a high index of refraction indicated that it might be useful in optics. No large boules* of strontium titanate had been synthesized previously, and none have been found as natural occurrences. The flame fusion process, invented by Verneuil in 1904, was first applied to grow large crystals of ruby and has since been used extensively to grow crystals of corundum and spinel on a commercial scale. Only during the past nine years has this technique been applied to the growth of large single crystals of other high melting compounds such as rutile, mullite and ferrites.

Jul 1, 1955

By K. Fallenius

Since 1970 a new series of pneumo-mechanical flotation machines has been developed by Outokumpu Oy. The cells have a completely new type of mechanism based on a recently-developed theory of conditions necessary for dispersion of large amounts of air. The mechanism was developed in 3 cu m cells and scaled to 16 cu m cells. Rotor and stator description, scale-up theory, and practical experience with the 16 cu m cell are presented.

Jan 1, 1976

By C Gunther

Secondary minerals are the result of a process of concentration and enrichment and are commonly richer than the primary minerals of the same deposit. Secondary ores that contain abundant sulphides are commonly dibtinguishable in the field from primary ores; this distinction is more difficult with ores that carry a small quantity only of sulphide minerals, and microscopical examination of the ore in thin section is advisable in all doubtful cases. It is frequently difficult, and in some cases impossible, to determine the primary or secondary character of quartzose gold ores. The safest guide is the presence or absence of gaseous or fluid inclusions in association with the ore minerals; such primary association coupled with a lack of traces of oxidation is indicative of primary origin. Any ore that carries traces of oxidation, such as iron stains, dendritic oxides of manganese, kaolin and so forth must be considered to have been acted upon by surface agencies, and secondary enrichment must be suspected. Further examination, however, may indicate that the contained value is primary, and, therefore, persistent in its vertical distribution. The manner of occurrence of secondary minerals is frequently characteristic; secondary minerals, being due to the action of surface waters, are commonly found in cracks through earlier minerals, or as crusts lining vugs or surrounding nucleal masses, or in general, in some distribution later than and not conforming to the arrangement of the primary minerals. Secondary sulphides are often found as soft black pulverulent masses or coatings, although they frequently occur well crystallized or as

Jan 1, 1932

By G. C. Bateman

The Workmen&apos;s Compensation Act of Ontario was passed in 1915 and Miners&apos; Phthisis was added to the list of compensable industrial diseases in 1916. Under this provision of the Act only about two cases were compensated per year. In 1924, The Department of Public Health made a survey of miners in the four principal camps—Sudbury, Porcupine, Kirkland Lake and Cobalt—and the survey indicated that an alarming proportion of the men exposed to dust had silicosis in one or other of its several stages. A number of conferences were held between representatives of the Department of Mines, the Department of Public Health, the Compensation Board and the mine operators. The operators were advised that in the earliest stages of silicosis there was no physical disability and if men in that stage were removed from underground there would be little danger of permanent disability. They were further advised that if active steps were taken at once to compensate men that had some real disability and remove from the mines men in the early stages of silicosis, the first cost would be the greatest and thereafter their liability should decrease. As a result of this advice, and having at that time no reason to doubt the findings of the survey, the operators agreed to do all that was asked of them and cooperate with the Government in the steps believed necessary to meet the situation, and to provide compensation for the men affected. Amendments in 1926 Arrangements were made for the necessary amendments to the Mines Act and the Workmen&apos;s Compensation Act and these amendments were passed in 1926. The Amendment to the Mines Act provided that all underground employees must be the holders of certificates certifying that they were free from tuberculosis of the respiratory organs and further provided that the certificates must be renewed annually. The Government, however, at that time refused to adopt a form of certificate for applicants certifying as to their physical fitness for underground work. The Amendments to the Compensation Act defined both silicosis and

Jan 1, 1937