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Discussion of the paper of P. B. LIEBERMANN, presented at the St. Louis meeting October, 1917, and printed in Bulletin No. 127, July, 1917, pp. 1051 to 1062. P. B. LIEBERMANN.-As mentioned in my paper, a special investigation was made on the effect of dirt on the track, for the -express purpose of educating mine operators to the advantage of keeping their tracks clean. As to the benefit of clean tracks to the saving in battery consumption, that can be easily determined if the rate of discharge is known under existing conditions, that is, on dirty tracks. The tests have shown that tracks covered with coal dust cause an increase in draw-bar pull of about 30 per cent. The battery discharge table will show the capacity corresponding to the new rate of discharge and will thereby disclose the possible saving in battery consumption. The difference between dirty tracks and clean tracks will be found large enough to have an appreciable effect on the size of the storage-battery locomotive, and for a locomotive of any given size it may mean

Jan 1, 1918

By S. S. Hartranft

FuRnace-men of the present day agree very nearly as to the best cooling-devices for the protection of blast-furnace hearths and boshes, and the best location of the cooling-system in the brick-work for the maintenance of favorable furnacelines throughout the blast. The replaceable bronze and copper plates are practically faultless; and there seems to be no reason why a furnace-hearth and bosh should not be held in good condition, by intelligent management and the use of replaceable plates, for a period several times the length of the average blast of to-day. While furnace-men have taken these .precautions to protect the hearth and bosh beyond the life of the lining, the portion of the lining above the mantle has been partly protected by some and wholly neglected by others. Some would not construct a furnace without mantle-plates, and others would not construct a furnace with them. In most cases, furnace-men have either trusted to Providence or to the bosh-plates for the continuance of favorable working-conditions above the mantle, and the prolongation of the life of the lining; consequently furnaces are constantly blown out for repairs to the lining, or for relining, when the hearth and bosh are in good enough condition to last through another blast. The following extract from one of Mr. James Gayley's con-

Jan 1, 1901

W. P. WHITE,* Washington, D. C. (written discussion?).-The authors seem to have proved that for a phenomenon as irregular as the one they were investigating there was no perceptible conduction effect in the platinum wire. It should be mentioned, however, that the conduction of heat to and from small wires is not proportional to their surface and might give unexpected value, varying largely with the medium in which the wire was situated. Attempts to eliminate a conduction effect in the wire by extrapolating the curve obtained by using different sizes have in some cases given incorrect results, so that the authors' result should be applied with great care as a guide in other cases. The difference in size of wire employed by them is really rather small. If the desire had been to find out how great the effect was instead of merely to demonstrate its absence, a greater difference of diameter would, of course, have been selected. The sharp gradient immediately in front of the burning portion of the cigar is quite surprising at first sight. The weight of air coming from a flame is considerably greater than the weight of material burned, and it would be thought that this stream of heated air would heat very con-siderably the material not yet reached by the zone of combustion. Pos-sibly the heat is exhausted in evaporating moisture from the material. In that case the cigar is really a sort of regenerative furnace, except that it is not air but the, material which is preheated, and the pre-heating produces dryness rather than increase of temperature. Whether or not this is the case would be shown by finding how hot a thoroughly dry cigar would get.

Jan 12, 1919

The Library of the above-named Societies is open from 9 A.M. to 10 P.M. on all week-days, except holidays, from September 1 to June 30, and from 9 A.M. to 6 P.M. during July and August. The Library contains about 55,000 volumes, including sets of technical periodicals and the publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library can render valuable service through correspondence; letters requesting information will receive special attention. The Library is prepared to furnish references and copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish general information as to the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may be what is desired and not, include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape. The members of the Institute can be of service to the Library by forwarding copies of mining reports, maps privately issued, and similar material, which will be classified, indexed, and made available to other members. Suggestions for additions to the Library, either by purchase or personal solicitation as gifts, will be welcomed. It is hoped that members while in the city will use the Library freely, and assurance is given that most careful service will be rendered to them.

Jan 9, 1915

By E. C. Roberts

TO facilitate some recent microscopic investigations it was necessary to devise special mounting techniques for the polishing of two quite different metallographic specimens. These techniques are extremely simple and are submitted for whatever value they may be to other investigators. The first specimen mount proved very satisfactory for the study of untempered martensite. Since it was undesirable to heat the specimen, lucite or bakelite mounting materials could not be used in the conventional manner. A cold mount was made by drilling a hole of the same diameter as the specimen in a cylindrical piece of polystyrene then press- ing the steel specimen into the hole on an ordinary vise. A prefabricated disk of lucite should work equally well. The only precautions necessary are that the hole be drilled out cleanly and the piece of steel be pressed into the plastic uniformly, otherwise the mount will crack. The second type of mount was required for the study of slag specimens by reflected light. Mounting these specimens in bakelite and then attempting to rough finish the surfaces on graded emery papers resulted in a considerable amount of chipping and breaking out of the slag particles. This made further satisfactory polishing almost impossible. It was found, however, that if the bakelite-mounted specimen was first rough finished to a point where a good specimen surface became visible, the interstices in the specimen surface could be filled and the polishing completed. This filling was accomplished by placing a small amount of lucite powder in the bottom of the steel specimen mold then reinserting the bakelite-mounted specimen on top of the lucite powder. Reheating the mold to the proper temperature and applying the required pressure resulted in the formation of a thin disk of lucite on the bottom of the bakelite specimen. By carefully grinding the lucite away a uniform surface including the slag specimen was obtained and further polishing was unhampered by slag disintegration.

Jan 1, 1951

By J. L. Leland Myer

Some of the early experiments on the oxidation temperature of coal1 were undertaken in England in connection with a study of self-heating, or spontaneous combustion. It was then suspected that coals with low oxidation temperature were most likely to ignite by self-heating, but further experiments showed that many additional factors were involved. The oxidation temperature has importance as a physical property or characteristic of the coal. While only a few of the physical properties have been studied, they appear to have basic significance2 in the ultimate classification of all coals. When reliable data become available on the oxidation temperatures, as determined by standard and adequate methods, it should provide an additional basis for classification and comparative evaluation. Oxidation Temperature Defined For such a heterogeneous substance as coal is known to be, no simple definition of oxidation temperature can be established on a theoretical basis. If coals were homogeneous and of simpler structure, the accepted definition of "ignition temperature " as applied to simple gaseous mixtures might be adopted; that is, the temperature at which self-heating of the mixture sets in. But most coals self-heat slightly even at storage temperature, as evidenced by spontaneous combustion, and the definition for gases cannot be applied to coals with any exactness. By subjecting coals to suitable experimental conditions various oxidation characteristics can be obtained and examined for critical or significant stages of the oxidation process. Oxidation temperature itself must then be defined on the basis of such experimental results. Experimental Methods Attempts to determine critical points in the temperature functions of coal undergoing oxidation have resulted in the following experimental methods:

Jan 1, 1932

By G. P. Moore

BOLIVIA still remains among the oil countries that have proved oil acreage but no production which is being marketed. No steps have been taken during the past year to provide facilities for transport of Bolivian oil to market nor are any known to be contemplated for 1930. The only active operator to date is the Standard Oil Co. of Bolivia, subsidiary of the Standard Oil Co. of New Jersey. The potential production from completed wells is practically unchanged from the 1928 figure of 6000 bbl. daily. As far as is known, there has been only one completion during the year 1929. This is the Machareti well, which is about 50 km. north of Villa Montes along the road to Charagua. The well is reported at about 250 bbl. daily initial production. The gravity of the oil is not known but is presumed to be about 40" Bé., the average for the region. The Standard Oil Co. of Bolivia has five strings working on various parts of its concession. No new locations have been made definitely. Company Activities There was no change in the situation of American holdings in Bolivia during 1929. The oil rights of an English company, acquired under a special colonization contract with the Bolivian Government, are being negotiated in New York and may mean the entrance of another of the large American oil companies in Bolivia. The Sucre Syndicate sold its holdings to the Standard Oil Co. of Bolivia during the past year. .A local company called the "Aguila Doble" was formed during 1929 to drill a well or wells near the town of Cochabamba on structures mapped by a local geologist. It is reported that the Government is buying about one-fourth of the capital stock of this company for 500,000 Bolivianos (about $180,000). The company has not yet raised sufficieht funds to buy drilling equipment so that no operations have been started. According to the statements published in La Pas, this company has acreage on seven anticlinal structures near Cochabamba. This area lies about 8500 ft. above sea level on the eastern Hank of the Andes Moun-

Jan 1, 1930

RAYMOND M. Howe (author's reply to discussion*).-Dr. Unger states that magnesite will hardly supersede dolomite in fettling after a heat; that it is hard to believe a slag composed of oxide of iron containing about 6 per cent. of phosphorus is the active corroding, agent in a boil in a furnace; and that boiling cannot be said to be the result of the chemical action of a high-phosphorus slag on a basic bottom. These are well-established facts that no one would venture to question. The authors were misinterpreted in the statement that "in the summary, it is claimed that magnesite low in lime, or of greatest purity, ranks first in resistance to slaking," etc. On the contrary, the position has been taken throughout that while a low lime content is advantageous, the presence of several per cent. of iron oxide (an impurity), is necessary in order to confer the proper bonding and sintering properties in dead-burned grain magnesite to be used for furnace hearths. We cannot subscribe to the view that pure magnesia is no better fitted for a refractory than pure lime,' nor that the pure natural varieties of magnesite; such as Grecian or Washington, must necessarily be burned with silica and oxide of iron to produce a satisfactory material. On a small scale, pure magnesia has been satisfactorily used as a refractory in the form of crucibles. In the production of dead-burned grain magnesite from the Grecian or Washington mineral, iron oxide is added but the addition of silica is neither customary nor desirable. It is possible to manufacture brick of good quality from both the Grecian and the Washington material without adding either silica or iron oxide, providing they are burned at a sufficiently high temperature. This is regularly done on a commercial scale both in America and abroad when brick of. exceptionally high refractoriness or special purity are desired. The following analysis is of an English brick of Grecian magnesite which is extremely low in all impurities.1

Jan 6, 1919

By F. L. Wolf

THERE is a tendency on the part of practical foundrymen to accept with reluctance the results of tests on sands, binders, and. such materials made in the chemical laboratory alone. They feel that such tests frequently emphasize and measure properties that are of minor importance and fail to take account of characteristics that are important in determining the value of the material in actual practice. Experience seems to indicate that the most thorough and conclusive, test for any new foundry material is an actual run in the foundry alongside of a standard material of known value. Such a test, however, involves certain difficulties and necessitates certain precautions. It is not always easy to obtain a fair trial for a new material. We all have certain prejudices, which unconsciously affect our judgment to a marked degree. A practical test frequently involves so many workmen, each of whom reacts in a different manner to the test, that; the personal equation becomes very, complex and the true results of the test are obscured. There are times, too, when a thorough experimental trial of a material would interfere too much with the rush of work in a department or would hazard the quality, of the product to such an extent as to make it inadvisable. Under such conditions a laboratory test is advisable before the material is sent into the foundry. These tests should be made as practical as possible and so closely related to foundry practice as to give a true index to the value of a, product for the purpose desired. Core sands and molding sands are as numerous "as the sands of the sea" and vary as much in quality. Old sources of supply are continually failing and new ones must be opened, so that we must continually search for new and better grades of sand. During the past year, the Ohio Brass Co. has developed tests for sands', cores, and binders which bear a close relation to the particular use to which these materials are put in

Jan 9, 1920

By Ralph Arnold

WHILE much geological work and drilling have been done in Venezuela, the incompleteness of geological evidence obtainable and the restricted areas in which drilling has been done make any estimates of oil resources extremely speculative. Nevertheless, it is felt that the data given are justified, in the belief that the ideas of a geologist familiar with the region are better than those of a promoter. The oldest beds of interest to oil men are those of the Cretaceous, which are well developed in eastern Venezuela and about parts of Lake Maracaibo. In both cases, a hard massive limestone is overlain by a great thickness, most of which is shale. In the west, in places this shale is more than 2000 ft. (610 m.) thick, while in the east it may attain 3500 ft., (1067 m.). The limestone and parts of the shale are oil producing. In the east, the Tertiary where present is almost entirely covered by the Quarternary, but in the west it is well developed. In probable unconformity over the Cretaceous shales is found a series of sandstones and shales, which may beg called the lower coal series. It is well developed southwest of the lake, where it is the oil container, and is probably the lowest series exposed east of the lake. Above this is the Pauji shale, which is probably the point of origin of all the oil east of Lake Maracaibo and in the State of Falcon. It has a thickness of about 3000 ft. (914 m.) in the Mene Grande region. The upper coal series is developed as a great thickness of sands, shales, and clays, with some partly consolidated limestone. Its thickness may be as great as 10,000 ft. It is the oil container of the Falcon-El Mene region and a probable location for oil in some of the area about the lake. It may or may not include the so-called Maracaibo series in which the oil is found at Mene Grande. Over much of Venenzuela, the Quarternary is present in unknown thickness, which probably is not great. It obscures oil structure in all cases and presents the greatest hazard of oil exploration for the fields which probably exist below.

Jan 7, 1922

By H. E. Doerr

THE writer has been unable to find much information relative to tests made to determine the effect of forging on the specific density of steel. The opinion, however, among men engaged in the business, seems to he that forging greatly compresses or consolidates the steel. While such is doubtless the case with spongy or porous steel, the following experiments indicate that there can be little or no change in the density with steel initially free from cavities: Ten ingots of basic open-hearth steel cast as shown in Fig. 1 were used in the experiments. All the specimens were 0.53 carbon with all other elements the same, the analysis being determined from drillings taken midway between the center and outside of the upper end, as shown in Fig. 2. The specimens were selected from over one thousand ingots so that the tests could be comparative for the work done in forging only, but no two of the ingots were cast in the same heat. Each ingot remained in the mold approximately 30 min., when it was removed and air-cooled. About 12 hr. later, when the temperature had been reduced to approximately that of the surrounding atmosphere, the head was discarded and the ingot heated in an oil furnace to approximately 2250° F. (1235° C). Approximately 1 min. was required to forge under the steam hammier to 1 ¼ in. (31.75 mm.), rough diameter, as shown by the dotted lines in Fig. 2. All ingots were allowed to air-cool after forging. Cylinders ½ in. (17.7 mm.) in diameter and ½ in. high were then turned from the forged and unforged parts of the ingots and numbered. The ten pairs of specimens were submitted to Louis E. Endsley, Professor of Railway Mechanical Engineering, University of Pittsburgh; A. N. Talbot, Professor of Applied Mechanics, University of Illinois; L. Z. Slater, chief chemist, Scullin Steel Co., St. Louis, Mo. No in-formation was furnished as to which specimens were forged or unforged and each laboratory used the same specimens, submitting the average of three independent determinations, a tabulation of which is shown in the accompanying table in which the laboratories are designated by

Jan 1, 1919

By J. Jones-Parra

In previous Technical Notes, W. R. Rose' and W. Purcell have discussed the capillary pressure data presented by Welge.' Welge obtained capillary pressure curves of the imbibition type in which it was necessary to apply to the apparent wetting phase a greater pressure than that of the non-wetting phase to complete the cycle and reduce the non-wetting phase saturation to low values. Rose suggests in his Note that conditions of equilibrium could not have prevailed, since the. non-wetting phase pressure must always be the greater. Pur-cell in his Note, proceeds to postulate a pore system consisting. of a series of "holes in a doughnut," in which he contends that under equilibrium conditions it is necessary to resort to negative capillary pressures before significant wetting phase displacement can take place. There is a remarkable similarity between the shape of the capillary pressure curve calculated by Purcell and those measured by Welge. It is the purpose of this Note to show that, because Purcell neglected to account for the behavior of the residual wetting phase saturation, his system was not in equilibrium during imbibition; and, furthermore, that if his system had been in equilibrium, negative capillary pressures would not have been possible. In Purcell's pore system, the residual wetting phase will form pendular rings at the interstitial spaces existing somewhere within the system, for example, such as those spaces between "doughnuts" as shown in Fig. 1. The true capillary pressure is that across the pendular ring interface, and for the system to be in equilibrium the pressure drop across all interfaces must be the same, including that across the interface in the tight pores A of diaphragm B (Fig. 1). As the pressure across the cell is reduced, the advancing interface will move into the pore from the diaphragm, but at each pressure, the curvature of the pendular rings must be the same as that of the advancing interface if equilibrium is to prevail. Since equilibrium conditions are the basis for the entire argument, it follows that pendular rings must grow as wetting phase enters the pore, that is, as the pressure across the cell is lowered. In Purcell's calculated curve, the residual wetting phase saturation remains constant as the capillary pressure decreases. Thus, his curve does not represent an equilibrium process.

Jan 1, 1953

By J. N. Houser

THE industrial relations between the Tennessee Copper Co. and its employees have developed a number of interesting things and have been most, profitable to the employees and to the company. It is noteworthy that considerable has been done without a formal organization of any kind built up through the efforts of the company. From time to time there have been discussions regarding the advisability of a formal organization and the decision has always been in favor of the present method. In the year 1919, the company was dealing with its employees through union committees and, after an understanding was reached, satisfactory results began to be obtained, but as time went on the committees did not function and it came to a question of how to reach the men. For the past two years, about once a month, but at no stated time, there has been a meeting with a committee of employees consisting of 40 or 50 men out of 700. This committee is secured by notify-ing the locals. In addition, the Service Department notifies a number of men not represented in the union, so as to have a large representative committee. The meetings are on company time and the men are rotated, so that in time every employee attends , at least one meeting. All department heads and a number of foremen also are present. The operating plans and policy of the company are set out at the meetings and the market outlook for products is discussed. Explana-tions are also given of anything that has come up since the last meeting which affects the employees, and an effort is made to inform them of what will probably happen in the next month or two. Once a week there is a meeting of department heads with the manager, for discussion of all operations as a whole and such depart-mental details as seem advisable. When the depression started, it was necessary to curtail operations and the reasons were carefully explained; before the men were laid off, the employees as a whole were advised of the coming layoffs through these meetings. They were also advised generally who would be retained and given an opportunity to express their agreement or their. disapproval. In fact, an effort was and is being made to keep the employees advised in advance of matters affecting them and to give them full opportunity to express themselves.

Jan 12, 1922

By F. C. von der Weid

The mining district of Sao Fidelis, in the northern part of the State of Rio de Janeiro, is situated on the Paraiba River, where it crosses the Serra do Mar (Mountain of the Sea), in the center of a mountainous country having numerous graphitic outcrops. For a long time, these outcrops were irregularly explored by local people, who had little means and no technical advice. A few years ago, the Cia. Brasileira de Minerasgo de Grafite took over the control of some of the more important outcrops and entrusted to me the task of studying the ores and establishing a flowsheet for a pilot plant to be situated in São Fidelis—the ore to be concentrated being mostly of a very high grade. Mineralization and Ores The rocks of the district are mostly gneiss and crystalline schists, with occasional interstratification of dolomitic limestone belonging to the Archean Brazilian Fundamental Complex. The general direction of the beds is roughly between 60" and 80°E., with variable dip, generally nearly vertical. Mostly, direction and dip of the graphitic outcrops is concordant with the embanking gneisses or schists. These outcrops seem to be aligned in two or three parallel zones (Pádua, São Fidelis, Mac- abu), the Sao Fidelis zone being the best known and the most important to date. Two outcrops of the São Fidelis zone, Saudade and Sao Benedito, are now being exploited. Mining has been carried out, so far, on a small scale. The mineralization consists of a vein of nearly massive graphite in a very compact, partially granitized gneiss, with vertical dip. The vein is most irregular, with nests and lenses irregularly distributed along the fracture plane. The ore consists chiefly (particularly in Sao Benedito) of massive graphite appearing and disappearing along the main direction of the vein, forming a succession of irregular lenses in a sort of rosary design. The average width is more or less one foot, with variations from zero to 6 feet. The lode minerals are quartz, a little feldspar and garnet (the latter having its origin perhaps in the embedding gneisses), with rare ferruginous clays on the outcrops. In Saudade a little pyrite, pyrrhotite and chalcopyrite is found occasionally, as well as a carbonaceous mineral, very light, black and shiny, with conchoidal fracture, looking like a sort of jet. The composition of this mineral has not yet been established, but it seems to be very complex. The mineralization seems to be hydro-thermal at a rather low temperature, perhaps mesothermal. The paragenesis, according to samples from Saudade, seems to be as follows, the earlier minerals being listed first: pyrrhotite, pyrite, chalcopyrite, with quartz concomitant to the three and graphite formed later. Age of the mineralization is still uncertain, owing to the very in-

Jan 1, 1948

By F. C. von der Weid

The mining district of Sao Fidelis, in the northern part of the State of Rio de Janeiro, is situated on the Paraiba River, where it crosses the Serra do Mar (Mountain of the Sea), in the center of a mountainous country having numerous graphitic outcrops. For a long time, these outcrops were irregularly explored by local people, who had little means and no technical advice. A few years ago, the Cia. Brasileira de Minerasgo de Grafite took over the control of some of the more important outcrops and entrusted to me the task of studying the ores and establishing a flowsheet for a pilot plant to be situated in São Fidelis—the ore to be concentrated being mostly of a very high grade. Mineralization and Ores The rocks of the district are mostly gneiss and crystalline schists, with occasional interstratification of dolomitic limestone belonging to the Archean Brazilian Fundamental Complex. The general direction of the beds is roughly between 60" and 80°E., with variable dip, generally nearly vertical. Mostly, direction and dip of the graphitic outcrops is concordant with the embanking gneisses or schists. These outcrops seem to be aligned in two or three parallel zones (Pádua, São Fidelis, Mac- abu), the Sao Fidelis zone being the best known and the most important to date. Two outcrops of the São Fidelis zone, Saudade and Sao Benedito, are now being exploited. Mining has been carried out, so far, on a small scale. The mineralization consists of a vein of nearly massive graphite in a very compact, partially granitized gneiss, with vertical dip. The vein is most irregular, with nests and lenses irregularly distributed along the fracture plane. The ore consists chiefly (particularly in Sao Benedito) of massive graphite appearing and disappearing along the main direction of the vein, forming a succession of irregular lenses in a sort of rosary design. The average width is more or less one foot, with variations from zero to 6 feet. The lode minerals are quartz, a little feldspar and garnet (the latter having its origin perhaps in the embedding gneisses), with rare ferruginous clays on the outcrops. In Saudade a little pyrite, pyrrhotite and chalcopyrite is found occasionally, as well as a carbonaceous mineral, very light, black and shiny, with conchoidal fracture, looking like a sort of jet. The composition of this mineral has not yet been established, but it seems to be very complex. The mineralization seems to be hydro-thermal at a rather low temperature, perhaps mesothermal. The paragenesis, according to samples from Saudade, seems to be as follows, the earlier minerals being listed first: pyrrhotite, pyrite, chalcopyrite, with quartz concomitant to the three and graphite formed later. Age of the mineralization is still uncertain, owing to the very in-

Jan 1, 1948

Howe Memorial Lecture The Howe Memorial Lecture, in memory of Henry Marion Howe, Past President of the Institute, was authorized in April, 1923, as an annual address to be delivered by invitation under the auspices of the Institute by an individual of recognized and outstanding attainment in the science and -practice of iron and steel metallurgy- or-metallography, chosen -by-the Board-of Directors upon recommendation of the Iron and Steel Division. The following were the Howe lectures and lecturers for the years indicated 1924 What is Steel'., By Albert Sauveur.

Jan 1, 1938

An experiment substituting pneumatic crawler drills for large-diameter rotary rigs in overburden stripping operations has indicated significant bit cost savings for Perry and Hylton Coal Co., Beckley, W. Va. The test was conducted in the Egeria Mountains (part of the Appalachian Range), where about 30 m (100 ft) of overburden consisting of hard, seamy sandstone and shale must be removed to recover a 560-mm (22-in.) vein. Perry and Hylton operates ten surface mines and is presently developing three more for start-up in the near future. The company follows a progressive policy toward ecological concerns, incorporating a self-imposed systematic mining and reclamation program for mined lands which leaves the landscape in a suitable condition for further development by local communities.

Jan 6, 1976

No. 219. Assayer for gold-silver property in Ecuador. No. 220. Two engineers to go to Russia, 22-28 years old. Not engaged or married. Knowledge of some language other than English. To study conditions in Russia two summers and intervening winter. One man must have experience in oil-well operation or oil manufacture; the other, in mining or metallurgy. Salary £300 per annum, plus traveling and living expenses. No. 221. Position in metallurgical testing department. Initial salary $1600 to $1500. Candidate who has had industrial training and experience either in the manufacture and testing of steel or in electro- metallurgy preferred, but one who has had post graduate work in these lines will be considered. No. 223. Experimental and research laboratory in Wisconsin wants ,a man who has had experience in ore dressing, iron ore preferably. Salary $3600. Also, an iron metallurgist. Salary $3600.

Jan 7, 1917

W: 0. HOTCHKISS, Madison, Wis. (written discussion*).-Mr. George's paper on. "The Wisconsin Zinc District" is a very complete and clear description, which it is a pleasure to read. His discussion of the origin of the ores is the least satisfactory part, and Mr. George correctly states present knowledge when he begins his paragraph on a origin with the words "the general supposition is, etc." There is still much to be learned regarding the details of the processes by which the ores have reached their present situation. In this the Wisconsin district differs not at all from other mining districts. It is my hope that Mr. George and others, equally clear-thinking, who are in close touch with these operations will be able at an early date to give us more information on this subject.

Jan 3, 1918

By Merle L. Bowser, Lawrence W. Scott, John N. Murphy

The environmental status of underground mining operations is critical to the health and safety of the miners; particularly in a large mine, the multitude of interacting parameters that can favorably or adversely affect the environmental status makes the manpower requirement of the routine checking of specific areas and conditions a formidable one. While the concept of environmental monitoring for miners has been considered for some time, until recently the availability of sensors to reliably measure the parameters of interest severely limited the utility of such systems. The status of sensors for mine use and the evaluation of enviornmental monitoring systems is reviewed.

Jan 1, 1980