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By Jay J. Burns

TWO zinc concentrating mills are operated by the St. Joseph Lead Co. in St. Lawrence County, N. Y. The Edwards mill is operating at present only sixteen hours a day treating 400 tons daily. The metallurgy at Edwards presents no unusual problems therefore this discussion is mainly limited to the metallurgy of the Balmat ore. The Balmat mill has a capacity of 1,250 tons per day and the operating crew consists of three shift bosses each with five millmen per shift. Two crusher operators work on each of two shifts and one cleanup man on day shift. The repair crew is made up of a foreman and three repairmen, one of the repairmen being capable of taking over any operating job in the mill from shift boss down. Each millman is capable of handling the next job in line and several men in the yard crew are broken into handling the start-off job in the mill so that temporary shortages of men do not cause extensive overtime. Sphalerite, pyrite, and galena, the principal ore minerals, occur in a gangue of calcite, dolomite, and silicates, especially diopside, plus tremo-

Jan 1, 1947

By Chas. B. Dudley

A Discussion of the papers of Mr. James Gayley, on "The Application of the Dry-Air Blast to the Manufacture of Iron," and of Mr. J. E. Johnson, Jr., on "The Physical Action of the Blast-Furnace," by Messrs. Charles B. Dudley, R. W. Raymond, J. E. Johnson, Jr., William F. Mattes, James Gayley, David Baker, John Birkinbine and F. E. Bachman. (Washington Meeting, May, 1905.) CHAS. B. DUDLEY, Altoona, Pa.:-Pam not a blast-furnace man, and this always puts me it a disadvantage because I cannot go into the details of the making of iron and steel. I have not the experience, and have to take the statements of other people, so what I say regarding the subject of this paper is not in the sense of an expert. When I first heard of Mr. Gayley's experiments, I said to myself, " I fear they will result in failure, since, apparently, Mr. Gayley has forgotten one chemical fact, namely, that carbon does not combine with oxygen in the absence of water-vapor." This fact which was so astonishing when it was first brought out some years ago, and which those who are interested may find in the Journal of the Chemical Society of London, for 18S5, page 349, and 1894, page 611, led me to think that the drying of the air would be a mistake. The general subject of the influence of water-vapor on chemical action is a large one; but the special point in which we are for the moment interested, namely, the influence of water-vapor on the combustion of carbon, was especially treated by Mr. H. B. Baker, in the papers referred to. Apparently, however, as the result of Mr. Gayley's experiments, we are to learn that the amount of moisture still left in the desiccated air is sufficient to secure perfectly satis¬factory combustion. In thinking over Mr. Gayley's paper, it occurred to me that there were two alternatives, either of which might be chosen, namely, we might dry the air as Mr. Gayley does, or possibly we might, in a very much simpler way, simply saturate the air at a constant temperature, and thus get uniform working and

Sep 1, 1905

By H. Leslie Bullock

From aluminum to zirconium, the quantitative preponderance of quartz as a gangue material is well recognized. lf this material is to be efficiently removed, its variations must be understood. Variations with temperature are especially important. Too little attention has been given to the thermal polarization of quartz. Under closely controlled conditions, electrostatic upgrading is very reliable. For efficient separation, contact charges must be fostered and charges due to radiation, surface coatings, or thermal polarization avoided. This paper lists thermal transition points of quartz and shows their effect on actual separations. Simple separation tests with all factors except temperature held constant are recommended for determining transition points. With silica making up more than 27% of the earth's crust, its oxides comprising more than 59% of all igneous rocks, and quartz accounting for most of the main free oxides, the mining engineer is in constant contact with quartz, which may occur as a valuable mineral to be purified or, far more frequently, as a gangue material to be removed as completely and economically as possible. As a means of effecting such purification or removal, dry beneficiation is becoming more and more desirable owing to local water scarcities, wet waste disposal problems, or freezing conditions. One method that has been gaining particularly rapid acceptance is electrostatic beneficiation, or the separation of dry free-flowing materials by means of opposite surface charges, differences in potential, or differences in conductivity. Electrostatic beneficiation dates back to the 1870's, but only in recent years have newly developed methods and apparatus and a growing knowledge of solid-state physics widened the field for its economical application. Because the term "electrostatic beneficiation" has been rather loosely used in the literature, it has come to include both electrostatic and electrodynamic procedures. Attracting type separators, however, in which oper- ation is based on differences of surface charge or potential, are truly electrostatic, because the separation occurs in a substantially static field set up between oppositely charged surfaces. Separations with this type of equipment may occur at potentials as low as 1000 v and seldom require potentials as high as 30,000 v. In the new contact charge dielectric separators1 the variation in charge is produced by continuous contact and separation of the particles in the moving feed stream and these charges are fostered by the use of non-conducting support and feed surfaces and by handling the feed in the form of streams of appreciable depth. This favors uniformity of feed and allows higher production rates. The distinctive surface charge differences are set up on the separation of the particles according to Coehn's Law,2 which states that equal and opposite charges are generated on the separation of any two materials in contact and that the substance having the highest dielectric constant will be positively charged. The basic contact charge concept is reliable, but all electrical charges are transient and modified by the electrical conditions of the surroundings. Pyro-electric, photoelectric and radiant effects may modify or totally destroy the contact charges necessary for efficient separation, or contact with conducting surfaces may neutralize them. Such hostile conditions must be carefully guarded against, since they have led to many costly failures in the past. The most consistent difference in surface charges to insure good separation is produced by repeated uniform contact and separation of particles in the moving stream. The thickness of the feed stream possible with this method reduces the effect of contact with the supporting surfaces, but as some contact is inevitable, the best results may be assured by having the dielectric constants of the supporting surfaces between the dielectric constants of the substances to be separated. In general, the hard smooth surface of quartz makes it an ideal substance for electrostatic separation from most minerals. For instance, with calcite, starting with a feed containing 1.9% acid insolubles, one can produce a concentrate containing 0.30% acid insolubles with a tailings containing 21.7% acid insolubles and a yield of 92.8%. The color can be held at 92 or above and the tint at 1.7 or lower. Working with specularite iron ore, laboratory work has given a concentrate of 68.8% Fe., with an iron unit recovery of 96.7%. Excellent results are also in pros-

Jan 1, 1969

By J. C. Bradley

THE relation of annealing temperature to conductivity of copper wire has been determined. Conductivity hard was 98.26 per cent. After a 10-min. heating at 200°C. it was 98.69. By annealing 10 min. at 300° C. a large increase, to 100.93, occurred. Maximum conductivity, 101.15, was attained after a 500° C. anneal; thereafter it decreased to 100.53 after a 950° C. anneal. If copper is gassed the decrease is much more than this. Materials and Methods The work was done on high grade electrolytic copper, 99.942 per cent. copper plus silver, silver 0.0008 per cent. It was hot-rolled to >/4 in., then cold drawn to 0.080 in. The wire was cut into 25 5-ft. lengths and numbered 1 to 25 as cut. Four samples were tested hard. The others were wound into 5-in. diameter coils. For the 100° C. heating a coil was put into water, the water brought to boiling, and the wire kept at this temperature for 10 min. For the higher temperatures the coils were placed in envelopes of sheet copper, a little water added, and the envelopes sealed by folding over the edges twice, and hammering them together. This kept the air out very well. The envelope and wire 'were brought to the desired temperature; this was maintained for 10 min., then the whole was water-quenched.

Jan 1, 1927

By Michael S. Roscoe

In order to more accurately predict longwall surface subsidence over the Pittsburgh No. 8 Coal in Eastern Ohio, North American Coal Corporation's Quarto Mining Company undertook or participated in several subsidence studies. Due to the changing roof geology and rapid variations in the amount of cover two separate areas were investigated at two different mines to determine the subsidence response if any to these changes. Data generated from these studies were compared with NCB derived,data for accuracy and then used to predict subsidence under houses, gas lines and other critical man made structures. The following report summarizes the results of these studies as well as the subsidence case histories of gas lines, transmission towers, houses and water wells. Problems that were encountered during both phases of this process (investigation and subsequent application) are also included.

By Dick Whittington, W. R. Taylor

GENERAL In mid-1974, a representative of ARCO Petroleum Company walked into our Austin offices and asked for a permit for ARCO's first Clay West Mine site. This was the first in situ uranium mining permit issued in the United States. That initial permit, issued in January 1975, was for three acres. The four years since have been characterized by growth and change. Today there are 16 permits approved for approximately 1,540 production acres issued to five companies at eight sites in four counties. There are approximately seven additional permit applications being processed or on the verge of being submitted for an estimated 2,000 additional acres of production. As a rough gauge of the financial scope of this activity, at the typical 40 production wells per acre and an estimated $2,000/well, operators hale installed or committed $122 million for production wells. This does not account for the exploration and development wells installed to delineate the ore or the cost of processing facilities for extracting the uranium. HISTORY OF URANIUM MINING IN TEXAS Information I have concerning early in situ uranium mining activities is "sketchy" but the apparent first on-site test of in situ uranium mining was conducted between 1967 and 1971 at the Dueterstat site, north of Yorktown in Gonzales County, by City Service. Others ran tests at the Bruni site in Webb County and the Burns and Clay West sites in Live Oak County in the mid-70's. During this period, Texas Water Quality Board personnel in the central and district offices maintained a general surveillance of these various test activities. Regulation of in situ uranium mining was formalized with the issuance of a permit in January 1975 with the advent of ARCO's initial production scale (3 acre) effort in the Clay West area at the Moser mine site. Since 1975, the accelerating rate of mining and exploration activity is noticeable. There were 16 exploratory rigs operating early in 1977. This year, the rig count is averaging 46--a 287% increase. HISTORY OF LEGISLATION Paralleling this mining activity was state and federal legislation which subjected in situ mining to environmental regulation. The following is a brief chronology of the legislation that is directly or indirectly related to uranium mining. As most of you know, disposal wells are an integral part of most in situ uranium mines operating in Texas. They are used both during production and during aquifer restoration following production. The wells are regulated by the Texas Injection Well Act, enacted in 1961 by the Texas Legislature. In 1967, the Water Quality Act established the Texas Water Quality Board, and provided for the regulation of water quality by the so-called permit system. In 1969, the Solid Waste Act was enacted by the Texas Legislature. The legislation provides for control of wastes from manufacturing, mining, and agriculture. This Act regulated uranium surface mining activities until 1975 when the Texas Surface and Mining Reclamation Act placed responsibility with the Railroad Commission for uranium open-pit mining and surface mining of coal and lignite. In 1972, the Federal Water Pollution Control Act (Public Law 92-500) was passed. This legislation forms the legal base for the NPDES (National Pollutant Discharge Elimination System) and the subsequent point source effluent guidelines and standards. The November 6, 1975 issue of the Federal Register published interim final rules for Best Practical Treatment levels for effluent discharges from ore mining and dressing operations. Litigation was immediately initiated by eleven companies against these proposed rules, and they are currently being reconsidered for reissuance in 1979. In 1974, the Federal Safe Drinking Water Act (Public Law 93-523) was enacted. A part of this legislation is the Underground Injection Congrol Program. The regulations implementing this program have undergone various public hearings and it is expected that they will be published in the Federal Register before the end of 1978. In 1975, the Texas Surface Mining and Reclamation Act (Senate Bill 55), providing for the Railroad Commission's authority to require reclamation of surface mines, was passed. In 1977, an amendment to Senate Bill 55 was introduced that proposed to place regulation of in situ mining of coal, lignite, and

Jan 1, 1979

By A. V. UDELL

OF all the metals that have from time to time been called the "Wonder Metal," mercury, often called quicksilver, is probably the most deserving of this designation. A wonder metal it must have been to those workers of an earlier day who named it after that Latin god of commerce and gain, characterized as the fleet messenger of the gods and the conductor of souls to the lower world. The word mercury has been used to indicate a carrier of tidings, a bearer of news, a nimble or clever person, a hawker, and a skillful thief. All of these attributes, and more, are recognizable in this metal, the technical terminology of which is "Hydragyrum," meaning water-silver, and from which the chemical symbol "Hg" is derived. Fickle in its occurrence in nature, simple in its metallurgy, illusive in captivity, it serves man in life or death, in war or peace, in commerce, science and arts, in mining, agriculture, and forestry with a versatility found in no other element.

Jan 1, 1929

A. Bement, Chicago,Ill. (communication to the Secretary*):— Formerly it was the general practice of engineers to designate coal that is free from moisture and ash as " combustible," notwithstandirig that it contains oxygen and nitrogen. The origin of this practice was more particularly due to the requirements in connection with boiler-testing, which demanded a consideration of that portion of the fuel which took part in the combuition-process because results based on a unit of either moist or dry coal were not comparable, since both moisture and ash were recognized as variable quantities. Thus, a pound of " combustible " became a standard of value, and was treated as a constant before employing measurements of heating-power and calculating therefrom the percentage of efficiency. The recognition of this term " combustible " was an advance to be credited to the engineer rather than to the chemist, because the latter, not having to do with the interpretation of analyses in practice outside the laboratory, usually saw no reason for reporting results in terms other than those of the moist-coal composition. Some years ago I needed a table of fuel-composition in terms of moist, dry, moisture-free and ash-free coal, and of the combustible components. This table required the use of the word combustible in its proper sense, for the purpose of designating carbon, hydrogen, and sulphur, instead of including these three elements with oxygen and nitrogen, to which aggregate the term combustible was formerly applied. To make such a tabulation involved either the use of the inconvenient and cumbersome term, "ash- and moisture-free coal," or of some other representative term, and for this purpose I adopted the expression pure coal, which is short, simple, convenient, and technically correct. It is also harmonious, because it agrees

Jan 1, 1909

By H. L. Hazen

THIS is the story of the recent operations of the Standard Cyaniding Co., which owns the Standard mine, a low-grade gold property in sight of Highway 40 about thirty miles from Lovelock toward Winnemucca, Nev. The ore is mined by power shovel and cyanided after grinding to only 3/S in. A total direct cost of $1.24 was attained in 1941 on 600 tons a day. Mining operations ceased, under Government edict, in 1942, and only in recent months have been resumed. The operating difficulties of today are: (1) the high cost of supplies; (2) labor problems; and (3) Federal laws as interpreted and enforced by executive bureaus of the Government. Of these, the increased cost of supplies is the least important.

Jan 1, 1947

By Timothy Collins

There was once a speculative period of interest in small mining companies that is commonly referred to as "the uranium boom of the 50's." In the late 60's, there was a second mining stock boom: it centered around uranium and silver, when silver had reached a new high of $3.60. In the mid 1970Js, there may be a new boom in the making, and it appears that substantial public and institutional interest in mining equities will finally result in a viable long-term capital market rather than the boom-or-bust pattern of the 50's and 60's. The reason for Wall Street's renewed interest in mining is understandable: most mineral commodities have recently gone up in price. Domestically, these price increases have come in the wake of the inflationary spiral unleashed by years of unbridled government deficit spending and erratic fiscal and monetary policies. Internationally, of course, the biggest push for higher prices has come from third-world countries whose primary income derives from indigenous natural resources. Many of these countries-whose fiscal and monetary policies haven't been models of excellence either-have attempted to cope with the worldwide economic mess by forming cartels that could control the price of commodities. What's happened to petroleum is well-known; what's happened to copper, bauxite, phosphate, and uranium is part and parcel of the same syndrome.

Jan 9, 1975

By James Ruddy

THE medical program of the Climax Molybdenum Co. is under the supervision of the department of industrial medicine of the University of Colorado, of which James J. Waring, professor of medicine at the University Medical School, is director. Dr. Waring is consultant and direct supervisor of both the hospital and industrial medical department at Climax. At Climax the program is in charge of the medical director and the associate physician, Dr. Galen M. Hover. The hospital at Climax is completely equipped with all that is necessary for the practice of scientific medicine and surgery. Only graduate registered nurses with experience in industrial medicine are employed. Being only a few hundred yards from the portal of the mine. acci-

Jan 1, 1946

By M. J. Coolbaugh

There is a need for concepts and techniques developed specifically for blasting in areas where the rock is loose or highly fractured. Common practice has been to use techniques developed in hard homogeneous rock and reduce the amount and strength of explosive. However, this rule cannot cope with all of the special characteristics of highly fractured rock and has not adequately taken care of the problems of overbreak, gouging, and wall damage. The main problems encountered when blasting in highly fractured rock are controlling the amount of rock broken, minimizing the damage done to the remaining wall material, and adapting blasting methods to rapidly fluctuating ground conditions. In addition, because it frequently needs timber support right into the blasting area, there is also the problem of how not to shoot out the timber when heavy loading is needed in order to offset a loss of impact caused by deflection of the detonation wave off the numerous rock interfaces, and by the absorption of the wave by resilient clay particles. Another consideration is the fact that less attention needs to be directed toward producing satisfactory fragmentation of the broken rock. Those blasting methods designed for breaking hard rock into manageable segments are, as a rule, not needed in highly fractured rock which will usually break along its own numerous fracture lines.

Jan 8, 1965

By Alfred Weiss

Over the past 25 years hard-rock mining companies have developed a number of profitable computer applications which appear applicable to operations in the coal industry. The evolution of these applications are described and the most profitable discussed. The basic nature of these systems is that they must cut across organizational boundaries. While technological advances contributed significantly to the successful implementation of computers within mining, the human aspects related to organization, management and control of systems projects remain as key to future success in coal as they were and still are in hard-rock mining.

Jan 1, 1983

By W. D. BRENNAN

AS a rule the thoughts of engineers are more often directed toward the mechanical and physical conditions of mining practice than they are toward the disposition and the marketing of the product. This, I think, has been true of the coal industry to the present time not only among the engineering force but also generally true of operators. There has been a tendency to place the sales department in a rather secondary position; for a great many years there was a greater demand for coal than the supply would meet, so it was only necessary to increase production: either by expansion of operating mines, or opening new mines of greater capacity. While the production of coal is still a highly important phase of the industry, its enormous development throughout the country, the great advance in fuel, efficiency and economy, and the discovery of new reserves of competitive fuels have combined to create a buyers' market and force the present-day attention upon merchandising in modern ways. A buyers' market has a natural tendency to develop the keenest competition, frequently unscrupulous and nearly always profit-wrecking. Under such conditions bad practices are bound to grow and to extend until the industry is wrecked, or until wiser heads get together to reduce or eliminate unfair methods of competition. This is not so recent a condition as one might believe.

Jan 1, 1931

By W. F. Boericke

THE recent completion by the United States Aluminum Company of a $4,000,000 addition to its plant at Massena, N. Y., consisting of a large blooming mill and structural mill, gives this organization, a subsidiary of the Aluminum Company of America, the distinction of possessing the largest aluminum rolling mill in the world, as well as the first mil1 in this country to roll aluminum exclusively. The plant is located near the international boundary line between Canada and the United States, about 3 miles from the St. Lawrence River, to take advantage of the development of cheap hydroelectric power which is needed not only for the manufacture of structural shapes from the ingots, but in the reduction of alumina to the metal by the well-known Hall process as well. A power canal from the St. Lawrence River to the power house on the Grasse River at the plant provides for the waterflow, which, coupled with a drop of 47 ft. in 2% miles, generates 80,000 hp. through vertical turbines. An additional 60,000 hp. is purchased.

Jan 1, 1930

By J. L. Fitch, B. G. Hurd

The presence of gypsum in samples subjected to standard core analysis introduces serious errors in the measurement of water saturation and porosity. The magnitude of these errors, depending upon the type of analysis procedure used, has been evaluated experimentally and theoretically. Water-saturated pore volumes determined by vacuum distillation or retort procedures may be too high by as much as 48 per cent of the volume of gypsum present. The maximum error in this value determined by Dean-Stark extraction with toluene is 36 per cent of the gypsum volume. If pore space is measured by a Boyle's law type porosimeter the maximum erorr due to gypsum is 38 per cent of the original gypsum volume present. The conscientious core analyst may eliminate the errors caused by gypsum by either of two methods. He may apply suitable corrections for the water of crystallization removed from gypsum, or take special precautions to prevent dehydration of gypsum during core cleaning and alzalysis procedures. These alternatives are discussed and methods for obtaining reliable core analysis data are proposed. Gypsum (CaSO4 . 2H2O) occurs as a common mineral in many of the world's sedimentary basins. In addition to its presence as primary bedded evaporitic deposits, it is often found as secondary replacement zones and pore-fillings in host rocks. That it may cause false indications in porosity, both on neutron logs and in standard core analysis, has been generally recognized. False porosity interpretations from neutron logs result because the chemically bound water in gypsum attenuates neutrons as effectively as free water. Errors in core analysis result when gypsum is dehydrated prior to or during the analysis. Vacuum retort procedures used by many laboratories to determine fluid saturation and porosity effect a complete removal of water of crystallization from gypsum. The crystal water, distilled and collected with free water from the sample, is counted as water-sat11rated pore space. Dehydration of gypsum results in a decrease in volume occupied by calcium sulfate and a corresponding increase in pore volume. Thus, if gypsum is dehydrated by sample cleaning and drying procedures, subsequent porosity measurements with gas expansion or compression instruments will be high. The qualitative effect of gypsum on porosity determinations by retort procedures was discussed in a recent article by Bynum and Koepl3. They concluded that since false porosity was interpreted as being water saturated, determinations of oil content were not affected. Others in the industry, however, have pointed out that porosity values are often used with values of water saturation determined independently, e.g., from electric resistivity logs in making reserve estimates. Values of water saturation calculated from the formation resistivity using the Archie equation, S4= are actually low if values of are high due to gypsum. In this case, false porosity values due to gypsum could cause serious errors in calculations of oil-in-place. This investigation was made to determine quantitatively the effect of gypsum on porosity values determined by different core analysis procedures. EXPERIMENTAL PROCEDURES Dehydration of Gypsum The extent and rate of removal of water of crystallization from gypsum under conditions encountered in core analysis procedures were studied. Taken for the experiments were three types of relatively pure, naturally occurring gypsum, viz. selenite, satin spar and massive gypsum. Although all samples probably contained trace chemical impurities, each type lost the theoretical amount of water upon complete dehydration. An automatic recording thermobalance, similar to one described by Mauer2, was used to obtain dehydration rate data for samples heated in dry air. Water

By AIME AIME

The following abstract of the minutes of the final Adjourned Annual Business Meeting, held Nov. 12, 1912, in the office of the Institute, 29 West 39th Street, New York City, is here presented for the information of the membership at large. On the announcement by the Secretary that there was a quorum present, President James F. Kemp called the meeting to order. The minutes of the Adjourned Annual Business Meeting of Oct. 7, 1912, were read and approved. (Sec p. xi,Bulletin No. 71, November). Prof. Jos. W. Richards, in behalf of the Special Committee of the Board of Directors and the Council (Messrs. Richards, Kirchhoff, and Rand), withdrew the two proposed amendments to the Constitution offered by the said Committee at the Adjourned Annual Business Meeting of Oct. 7, 1912. (See Bulletin. No. 70, October, 1912, p. vi., and Circular Announcement No. 8, Oct. 15, 1912, p. 15.) Professor Richards presented a syllabus of the proposed amendments to the Constitution and By-Laws prepared by the Special Committee. Several members present discussed various sections of the proposed Constitution, and the Committee advised that the suggestions would he duly considered before submitting the final document, which would be duly presented and sent to the membership at large at least 30 days before the next Annual Business Meeting, Feb. 18, 1913. Professor Richards presented a resolution, seconded by Mr. Kirchhoff, making a change in the present Certificate of Incorporation, so that it would conform to the proposed changes in the Constitution and By-Laws; said resolution was unanimously adopted. Professor Richards presented another amendment to the Constitution, which had been purposely omitted from the printed list, but had been requested by many members, namely, the creation of a " Class of Fellows." This question was freely discussed at the Cleveland meeting (see Bulletin No. 71, November, 1912, p. 1348), and in view of the diversity of opinion it was-decided to present it in separate form for separate action of the membership at large at the Annual Business Meeting, Feb. 18, 1913. In answer to question, the President announced that the proposed amendments to the Constitution and By-Laws presented by Messrs. Corning and Stone at the Adjourned Annual Business Meeting, Oct. 7, 1912, and published in Circular Announcement No. 8, Oct. 15, 1912, were still on record. Professor Richards presented a syllabus of the proposed amendments to the By-Laws, and several sections were discused by members present, but no action of record was taken. Mr. Charles F. Rand read a letter from Mr. L. K. Armstrong, Sec-retary of the Spokane Local Section of the Institute, referring to the proposed amendments to the Constitution, and he announced that many of Mr. Armstrong's suggestions were, in one form or another, already incorporated in the proposed amendments submitted by the Special Committee. A special vote of thanks was passed to Dr. Albert R. Ledoux for the valuable assistance rendered by him to the Special Committee in the preparation of the proposed amendments to the Constitution and By-Laws.

Dec 1, 1912

By W. A. Eardley

FIFTEEN years ago the world's deepest oil well penetrated the earth about 7300 ft. That depth has now been more than doubled. Why has such deep drilling become necessary and how has it become possible? Three factors have had an important bearing: (1) Depletion of shallow zones, making it necessary to search for deeper producing measures. (2) The perfection of prospecting methods, which have been success- fully used to locate favorable buried structures, many at great depth. (3) Improvement in the quality of steels used for drilling.

Jan 1, 1940

By E. A. Holbrook

IN my thirty years of educational work in the mineral industries and other engineering fields, this past year has been the most unusual and difficult one. Contact with educators from other schools leads to the conclusion that the same situation is countrywide. The first of our difficulties came from the shortsighted policy of the Selective Service in taking out of the colleges, continuously, all engineering students as soon as they had reached their eighteenth birthday. England, Canada, and Russia, too, even in the midst of their critical war situations, had the good sense to keep their young engineering brains in college, for they realized the vital necessity of a steady flow of engineering graduates into the war industries and into the postwar peace industries. As a result of the policy of our Government, our engineering schools were left with only a handful of students who had been rejected for military service. Our colleges, faced with the prospect of several years without students and without income, hastened to give leave of absence to many of their competent teachers who quickly were taken into industry and in many instances are now being retained there at higher salaries than colleges are accustomed or able to pay their teaching personnel. We are finding it most difficult to induce these men to return to their former engineering teaching work. In my judgment, it will take us three or four years to restore our engineering departments to their former level in quality of instruction.

Jan 1, 1946

By Harold V. Pearce

(Chattanooga Meeting, October, 1908.) THE fire which occurred in the fall of 1906, at the works of the Boston & Colorado Smelting Co., Argo, Colo., destroyed entirely the gold- and silver-refinery of the plant; and in view of the development of modern practice in the refining of copper-mattes, etc., the management decided that it would be inadvisable to rebuild that part of the works for the continued use of the process which had been conducted therein for so many years as a metallurgical secret. This decision probably removes altogether from the sphere of practice the " Pearce " method for the separation of gold. At all events, it removes the business reasons which have prevented hitherto the publication of the principles involved. At the suggestion of Dr. Raymond, Secretary of the Institute, my father, Richard Pearce, the former manager of these works, has requested me to prepare a brief description of this process for the benefit of our members. Since I severed my connection with the Boston & Colorado Smelting Co. some time ago, I am indebted for some practical details to the present superintendent, Charles Rees, whose friendly assistance I would gratefully acknowledge. With regard to the history of the inception and development of this process by its inventor, Richard Pearce, I cannot do better than quote freely from his own notes and papers. HISTORY OF THE PEARCE PROCESS.' "In 1874 my entire time was directed to the improvements and additions to the plant at Black Hawk. The changes which I had made in the construction of the furnaces at Black Hawk proved so beneficial that I was requested to introduce the improvements at the branch works at Alma. These changes were carried out as speedily as possible, and proved of great advantage as compared with the old system. "The separation and refining of the gold from the matte now engaged my attention, and since previous experience in the treatment of gold-bearing matte and

Feb 1, 1909