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The Geophysics Education Committee has devoted several years to a consideration of the problem of training geophysi-cists. Past reports have dealt largely with fact finding and with the discussion of particular aspects of geophysical education. In the present report it is proposed to review the subject more comprehensively. This involves the question of what educational qualifications the geophysicist of the highest professional standards should possess, and the related question of what changes must be effected in existing educational institutions in order that prospective professional geophysicists may obtain instruction of the desired quality. The type of geophysicist here contemplated is one familiar with what is known already in the several branches of earth physics, and capable not only of following contemporary progress in any of these branches, but of contributing to that progress in a research capacity. Geophysics in its broadest sense, as has been emphasized repeatedly by this Committee, is the study of the physics of the earth and of terrestrial processes. This includes both the static and the dynamic characteristics of the gaseous, the liquid, and the solid portions of the earth, as well as its gravitational, thermal, and magnetic and electrical manifestations. Some branches of earth physics have been cultivated but slightly; others have reached an advanced state of development. Those branches whose development is sufficient to warrant explicit recognition in the form of organized Sections of the American Geophysical Union are: geodesy, seismology, tectonophysics, and volcanology, dealing with the rock constituents of the earth; oceanography and hydrology with the aqueous constituents; meteorology with the atmospheric constituents; and terrestrial electricity and magnetism with the electromagnetic manifestations. At present, instruction on the professional level in any of these branches of earth physics can be obtained in but few universities in North America. In most institutions where such instruction is undertaken different subjects are given in different and independent departments. Geodesy and hydrology are taught, if at all, as a part of civil engineering. The nearest approach to volcanology and tectonophysics ordinarily is represented by petrology and structural geology given

Jan 1, 1946

The Geophysics Education Committee has devoted several years to a consideration of the problem of training geophysi-cists. Past reports have dealt largely with fact finding and with the discussion of particular aspects of geophysical education. In the present report it is proposed to review the subject more comprehensively. This involves the question of what educational qualifications the geophysicist of the highest professional standards should possess, and the related question of what changes must be effected in existing educational institutions in order that prospective professional geophysicists may obtain instruction of the desired quality. The type of geophysicist here contemplated is one familiar with what is known already in the several branches of earth physics, and capable not only of following contemporary progress in any of these branches, but of contributing to that progress in a research capacity. Geophysics in its broadest sense, as has been emphasized repeatedly by this Committee, is the study of the physics of the earth and of terrestrial processes. This includes both the static and the dynamic characteristics of the gaseous, the liquid, and the solid portions of the earth, as well as its gravitational, thermal, and magnetic and electrical manifestations. Some branches of earth physics have been cultivated but slightly; others have reached an advanced state of development. Those branches whose development is sufficient to warrant explicit recognition in the form of organized Sections of the American Geophysical Union are: geodesy, seismology, tectonophysics, and volcanology, dealing with the rock constituents of the earth; oceanography and hydrology with the aqueous constituents; meteorology with the atmospheric constituents; and terrestrial electricity and magnetism with the electromagnetic manifestations. At present, instruction on the professional level in any of these branches of earth physics can be obtained in but few universities in North America. In most institutions where such instruction is undertaken different subjects are given in different and independent departments. Geodesy and hydrology are taught, if at all, as a part of civil engineering. The nearest approach to volcanology and tectonophysics ordinarily is represented by petrology and structural geology given

Jan 1, 1946

By D. H. Newland

During the year 1907 an investigation of the Clinton formation in New York has been carried out under the direction of the State Geologist, and a full account of the results has been prepared for publication.' The more important economic features of the report are summarized in the present paper. Previous knowledge of this, the type, section of the Clinton has been contributed mostly by Hall and Vanuxem in their reports for the Natural History Survey of New York, which were issued in their final form in 1842-43. Brief accounts of the ore-occurrences have been given by 13. T. Putnam? J. C. Smock: A. H. Chester: and E. C. Eckel.5 Prof. C. H. Smyth, Jr.,6 has discussed the origin of the Clinton ores in two papers, which, so far as the local occurrences are concerned, have removed all doubt that may have existed on that subject. Distribution of the Clinton Formation. The Clinton strata in New York State are restricted to a single belt, which extends from the eastern central part to the Niagara river, which it crosses, and thence continues for some distance into the province of Ontario. The New York

Jan 1, 1910

By S. E. Bretherton

Most metallurgists appreciate the great need of a process for the extraction and recovery of valuable metals from complex ore, where the presence of one metal increases the cost of extracting the other rnetals to such an extent that not any of the metals can be extracted at a profit. We need only refer to some of the mines in Colorado, Utah, and New Mexico, where oxidation has taken place and the sulphur, zinc, copper, and some of the iron and other metals have been leached out, large bodies of oxidized ore remaining, rich in lead, silver, and sometimes gold. These metals have been concentrated by the removal of the other metals, leaving a very desirable ore for treatment in the blast-furnace for the production of lead bullion, and recovery of the silver and gold. If lead is not present, the gold and silver metals are usually recovered by some method of milling, or the ore is shipped to a smelter, where it is mixed with lead ore or copper-iron sulphide ore from some other mine. In these same mines, when developed to greater depth below the leached or oxidized zone, the ore is found to contain the original mixture of sulphur, zinc, copper, etc., added to, or I should say left with, the lead, silver, and gold values; but instead of adding to the value of the ore, the presence of these elements, especially zinc, makes the copper, silver, and gold of less value, and often worthlees. Such was the experience of the oldest mines in Leadville,.Colo., until methods of mechanical separation of the lead from the zinc were developed sufficiently to allow of some profit by the making of a concentrate rich in zinc to be shipped to the zinc smelter, and sometimes a lead concentrate which could be shipped to the lead smelter; but even in these cases the waste of the different metals is a very serious matter. In the very best concentrating plants some zinc will be left in the lead concentrate, to be lost and to give considerable trouble in the lead-smelting furnace. On the other hand, some of the lead, with a large percentage of the copper and silver, will follow the zinc into the zinc concentrate, to be, perhaps, recovered by smelting the cinder or clinker left in the re-

Jan 1, 1915

By B. F. Koch

COPPER reverberatories develop large amounts of exit gases of a temperature in the neighborhood of 2000°F. The gases are not only of a noxious nature but must usually be disposed of at considerable heights above the yard level by a stack. Handling these gases at the temperature mentioned would require rather expensive construction of conveying flues and stack. Moreover, wasting such amounts of heat is certainly most uneconomical. Numerous investigations have indicated that waste heat boilers of the water-tube type are the most practical and economical means for utilizing that heat although the gases are heavily laden with rock dust and copper-bearing slag, which upon cooling form hard deposits on the surfaces of dampers or heat absorbing elements placed in the gas stream. Avoiding Slag and Dust Deposits Based largely on the experience of the paper industry in burning black liquor, a waste heat boiler design was developed a few years ago, providing not only extensive water-wall surfaces for cooling the gases below the fusing point of the slag but also settling out, as far as possible, the solidified particles of slag by creating low gas velocity. Matter carried in a stream of gases or air has a tendency to maintain its original direction upon a change in the direction of the flow of the conveying medium. Reverberatory waste heat boilers installed at Hurley and Morenci endeavored to utilize that tendency for the elimination of slagging particles at predetermined places and before they would strike the tube banks of the boilers. Both installations were successful in minimizing the slagging of boiler tubes and thereby minimizing the need for hand lancing. However, the low draft carried at the up-take of the reverberatory furnaces resulted in a positive pressure in the upper part of the furnace of the waste heat boilers, causing the emission of gases from lancing doors and making more difficult the already unwelcome work of cleaning the boilers by handlancing. Attempting to correct this nuisance as much as possible, the overall height of the Chuquicamata waste heat boilers has been reduced to the minimum considered necessary to obtain proper water circulation in furnace walls. Moreover, it is attempted to solidify slag and dust particles by providing large amounts of water-cooled surfaces before the gas stream reaches super-heater and convection banks of the boilers. The furnaces have been made as deep as an economical and practical arrangement of headers for water

Jan 1, 1952

By J. R. Long, T. R. Graham, C. W. Matthews, R. S. Dean

IN a previous paper§ the authors reported on the mechanical properties of a 65 per cent copper, 10 per cent manganese, 25 per cent zinc alloy as compared with similarly processed cartridge brass. Additional investigations by these laboratories, on higher copper alloys, have demonstrated that at lower zinc concentrations even larger amounts of pure manganese may be added to copper-zinc alloys without exceeding the single-phase solid solution limits, and that similar increases in tensile strength, yield strength, and hardness may be obtained without excessive decreases in ductility. Several compositions in this range showed also a decided color change with increasing manganese. The normal "brassy" color was considerably lightened and reduced to a faint yellow cast at 15 per cent manganese. With higher manganese contents the alloys were essentially white and similar in appearance to the nickel-silver alloys. From this work it appeared that it would be desirable to determine more completely the properties of the wrought and annealed white alloys. Accordingly, a more detailed study was planned of an alloy having the composition 70 per cent copper, 20 per cent manganese, and 10 per cent zinc. This alloy remained single-phase throughout the working and annealing cycles of the preliminary tests and appeared to be about the strongest of the white single-phase alloys. The project included also an investigation of additional alloys, deviating from this composition by 5 per cent of each of the three components to evaluate the effects of variation in composition; also a study of the properties of the central alloy made with silicothermic manganese. MATERIAL PREPARATION Electrolytic manganese, wirebar copper, and electrolytic zinc were used for the preparation of the alloys. Representative analysis of the electrolytic manganese seldom exceeds 0.01 per cent iron, 0.02 per cent sulphur and 0.02 per cent lead, with no silicon or aluminum. A typical sample of the silicothermic manganese metal contained 2 per cent iron, 0.81 per cent silicon, 0.i6 per cent carbon, and 0.36 per cent aluminum. Melting and alloying were performed in a high-frequency furnace with magnesia crucibles. Melts were deoxidized with small aluminum additions and cast into 25-lb. slab ingots. Care was exercised in deoxidation to avoid excessive amounts of residual aluminum, which has been found to have significant effects on alloys in this system. All ingots were hot-rolled at 1200° to 1300°F. and then cold-rolled with intermediate anneal-

Jan 1, 1945

By J. R. Long, T. R. Graham, C. W. Matthews, R. S. Dean

In a previous paper! the authors reported on the mechanical properties of a 65 per cent copper, 10 per cent manganese, 25 per cent zinc alloy as compared with, similarly processed cartridge brass. Additional investigations by these laboratories, on higher copper alloys, have demonstrated that at lower zinc concentrations even larger amounts of pure manganese may be added to copper-zinc alloys without exceeding the single-phase solid solution limits, and that similar increases in tensile strength, yield strength, and hardness may be obtained without excessive decreases in ductility. Several compositions in this range showed also a decided color change with increasing manganese. The normal "brassy" color was considerably lightcncd and reduced to a faint yellow cast at 15 per cent manganese. With higher manganese contents the alloys were essentially white and similar in appearance to the nickel-silver alloys. From this work it appeared that it would be desirable to determine more completely the properties of the wrought and annealed white alloys. Accordingly, a more detailed study was planned of an alloy having the composition 70 per cent copper, 20 per cent manganese, and 10 per cent zinc. This alloy remained single-phase throughout the working and annealing cycles of the preliminary tests and appeared to be' about the strongest of the white single-phase alloys. The project included also an investigation of additional alloys, deviating from this composition by 5 per cent of each of the three components to evaluate the effects of variation in composition and a study of the propertics of the central alloy made with silicothermic manganese. Material Preparation Electrolytic manganese, wirebar copper, and electrolytic zinc were used for the preparation of the alloys. Representative analysis of the electrolytic manganese seldom exceeds 0.01 per cent iron, 0.02 per cent sulphur and 0.02 per cent lead, with no silicon or aluminum. A typical sample of the silicothermic manganese metal contained 2 per cent iron, 0.81 per cent silicon, 0.16 per cent carbon, and 0.36 per cent aluminum. Melting and alloying were performed in a high-frequency furnace with magnesia crucibles. Melts were deoxidized with small aluminum additions and cast into 25-lb. slab ingots. Care was exercised in deoxidation to avoid excessive amounts of residual aluminum, which has been found to have significant effects on alloys in this system. All ingots were hot-rolled at 1200' to I300°F. and then cold-rolled with intermediate anneal-

Jan 1, 1945

IT will be recalled that when educational instruction for the mineral industry began at Freiberg, at the beginning of the eighteenth century, the original aim was to organize and systematize the procedures previously followed by young men in gaining familiarity with the technology then in use. There must have been many other ideas current, even then, as to just what a young man needed to learn in order to become capable of assuming responsibility for the supervision and direction of such technical work. The problem in Europe was decidedly different from that in nineteenth-century America, because some of the European mines were actually owned and operated by the governing authority and the others were supervised, regulated, and taxed by it. The American problem was the efficient performance of technical operations; the European one was regulatory supervision. It was natural, therefore, that in the development of educational processes in Europe stress was laid on those factors which conserved and protected the interests of the state. The study of mineralogy and geology, leading to correct judgments as to the workability and value of mineral deposits; assaying, which gave the means of quantitative measurements, as did surveying; chemistry, which furnished a better basis of understanding for assaying, mineralogy, and geology; and physics and mathematics, which are the bases for the understanding and efficient use of mechanical appliances, became the core of systematic instruction for the mineral industry. It was early recognized that men could learn more than was already known about all of these subjects and education took on that dichotomy which still characterizes it; the teaching of established knowledge to the unlearned, and that of extending of the bounds of knowledge, now loosely termed research, which after two and a half centuries of work still shows

Jan 1, 1941

EVERY dry thing that burns easily and multiplies or maintains fire by its own intrinsic nature can be put into an incendiary composition and various effects are produced. Some of these things are mineral combinations, like sulphur or its oil; some others, [163v] hot, dry, and subtle substances, like saltpeter; and some are. unctuous things, like fats and oils of any kind; while some serve because of dryness, like pith and wood. Some of these things are natural and some artificial But now I set aside the search for these differences in their composition. This is what I have found among all the ancient and modern things that I have been able to seek, and first, back in the time of Alexander the Great. Marcus Graecus, who was perhaps the inventor or a great experimenter and practicer of such things, writes of many of them. I have chosen some among these, and one* is this: In order to make it, he took Grecian pitch, alchitran, live sulphur, tartar, sarcocolla, niter, and petroleum oil, one part of each, and, in addition, a double amount of quicklime. He mixed it all with oil of egg yolks. Having put it in a well-covered and closed vessel of glass or glazed earthenware under warm manure, he left it for a month. Then, having liquefied it over a slow fire, always keeping the vessel well closed, he finally put this liquor in hollow sticks, in little pots, or in vessels expressly made, all with a little fuse fitted in the middle. If I should have to do this, I would say that a little gunpowder should be put in, which should give beginning to the fire so that it would ignite more easily. I have also found that another fire is made. For this sulphur is taken, or oil of sulphur if it is possible to obtain, petroleum oil or some rock oil, juniper oil, very well-refined saltpeter, and for one part of each of these five parts of asphalt; in addition, take goose or duck fat, pure black pitch, varnish, pulverized dove's dung, and enough aqua vitae to cover all the aforesaid things.. Then it is put in a glass vessel under warm manure for

Jan 1, 1942

By C. A. Wert

THE change in mechanical properties accompanying quench aging of carbon in a iron has been known for a number of years. Since the amount of carbon involved is rather small, however, no measurements could be made to correlate the property change with the state of precipitation of the carbide. Indeed, until a few years ago it was not plain which property might be used to indicate the state of the progress of precipitation. Some years ago the internal friction of solid solutions of carbon in a iron was demonstrated, and the use of this phenomenon to ascertain the amount of carbon in solid solution at any given time was developed. Shortly afterward the author made a number of measurements in which changes in electrical resistance, thermoelectric emf, and hardness were determined simultaneously with the internal friction (and hence with the precipitation) ? A little later Dijkstra and Wert measured the change in magnetic coercive force accompanying aging.' The present work was undertaken to inquire into the changes in yield strength accompanying aging. The work was done on specimens made of Puron. These specimens were 0.05 in. in diam and about 6 in. long. Though specimens of this small size are not ideal for yield strength measurements, such specimens are desirable for internal friction meas-

Jan 1, 1952

By F. W. Bradley

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

Jan 1, 1932

By J. B. Scuffham, G. A. Rowden

The use of ammonia as a leaching agent has been well-documented but only recently have its advantages been fully exploited on a commercial basis. When compared with conventional sulfuric acid leaching processes, the major advantage of ammoniacal systems is their ability to reject iron and many acid consuming gangue materials. Although metallic copper, nickel, zinc, etc. are dissolved rapidly in ammoniacal liquors at ambient temperature in the presence of air the sulfide ores of these metals are more resistant to this treatment. Sherritt Gordon Mines in Canada treats sulfide concentrates at its Fort Saskatchewan plant under pressure with ammoniacal am- monium sulfate solution to solubilize the non-ferrous metal values. Typical leach operating conditions are 80-95°C and 115- 128 psig. Although the metals present in the ammonical solution could be recovered via solvent extraction techniques, Sherritt Gordon Mines currently operates a pressure reduction process using hydrogen to yield metal powders directly from the ammoniacal solution. The basic Sherritt Gordon technology has been applied world wide for the treatment of nickel/cobalt concentrates.

Jan 12, 1973

By J. T. Pardee

INTRODUCTION PLACER is a Spanish word, the definitions of which include "an extensive bank of sand or gravel" and "a place where currents of water deposit particles of gold."l The term, probably first used in the western hemisphere by Spanish or Mexican gold miners, is now generally applied to all detrital deposits that yield valuable minerals by washing. In the Western States placer products other than gold, including the silver alloyed with it, are chiefly sapphires, produced in Montana, and platinum alloys recovered in California and Oregon. During the war tungsten ore (scheelite) was obtained from placers in the Atolia district, California, and a number of diamonds have been found in the Sierra Nevada gold belt. Small amounts of stream tin have been produced in the Black Hills of South Dakota and a little monazite sand in the Boise Basin. Idaho. Magnetite, chromite, ilmenite, zircon, and other useful minerals are more or less abundant in the beach placers of the Pacific coast and in the heavy residues of placer mining elsewhere, but the problems of profitably separating and marketing them remain to be solved. Minerals of lead, quicksilver and other metals occur in many of the placers and although not plentiful enough as a rule to be worth recover-ng, their presence has, in several instances, led to the discovery of valuable lodes, notably at Leadville, Colorado. Historical summary.-In New Mesico, Arizona, and Southern California, placer gold was mined by Mexicans and Spanish priests in the first half of the 19th century or earlier. With these exceptions history of placer mining in the Western States begins with Marshall's discovery of gold in northern California in 1848. During the next twenty years placers were found in all of the principal mining districts that are known today. The richer deposits were soon mined out but a relatively large production was maintained from the leaner deposits chiefly by hydraulic

Jan 1, 1933

By C. R. Kuzell

ALTHOUGH furnaces constructed of refractory brick have been oper-ated for many decades, there has always been an unfulfilled desire by the operators for a less arduous and more satisfactory method of patching weak spots and burned-out zones in order to postpone and to effectively extend the termination of a furnace campaign. Not only has this desire frequently arisen when small spots have approached incipient failure while the furnace structure as a whole was still in good condition, but also when larger areas showed signs of needing replacement. The availa-ble methods have been arduous, sometimes dangerous, inefficient with respect to the life of new refractory material used, and nearly always have necessitated interruption of the continuity of the furnace operations and therefore reduction in furnace production during the period of time required for the repair work. Most of these older methods have involved the replacement of masonry by refractory shapes in the weakened areas. Many attempts have been made to develop a method of patching the burned-out areas by spraying granular refractory material upon old surfaces. While some success has been attained in attempts to renew the grooved, corroded side walls and fettling, and the edges of hearths, there have been no known successful applications of the spraying method in patching the underside of arches of operating furnaces. The method developed recently at the Clarkdale smelter of the United Verde Branch of Phelps Dodge Corporation, at Clarkdale, Ariz., and described in this paper, has been found to be not only convenient and successful with respect to patching vertical or inclined surfaces, but has met with a marked degree of success in patching the parts of furnace arches that are exposed to flame, the successful result being obtained with-out interruption or interference with the continuity of furnace operations. ? It may be described as a method of renewing the interior refractory sur-faces of operating furnaces by pneumatic spraying of an aqueous suspen-sion of finely divided particles of refractory material. It has been used

Jan 1, 1939

By R. M. Bird

Few persons outside of the foundry trade have any conception of the great variety of sands now regularly specified and furnished, nor of the differences in foundry practice frequently resulting from apparently minor changes in sands. Conditions in each locality where the sands are mined and prepared necessitate special equipment designed to perform the work efficiently. The description that follows of the foundry-sand producing operations is typical of the areas in New York and New Jersey, and particularly refers to the operations of the George F. Pettinos Co. A few years ago the so-called Albany sands were dug by simple methods and hauled by horsecart to railroad. Depletion of sand near railroad sidings and extended use of automotive power have appreciably extended the area from which sand is now being dug. It is not unusual to haul 5 miles to the railroad. As stripping is quite shallow, 6 to 18 in., and the banks of usable sand generally run from 12 in. to 4 ft., it is economical to work the bank by benches so narrow that the overburden can be thrown by hand shovel to the exposed bottoms. In effect the top soil goes back to where it was, but on a lower level. Consequently the general surface appearance of a mined acreage is the same as before. This condition is in fact cutomarily required when a farm owner sells his sand in the ground. After such replacement, in the course of 3 to 5 years the soil is no less fertile than it was before mining. The sand itself varies as to grain and bond vertically and also along the breast. No mechanical equipment has been developed to compete with hand shovels and no machine has as yet been devised that grades the sand as required. Uniformity of sand, as shipped, depends first, last and all the time on the man on the job. Mixing equipment can change the appearance of the sand and mask its lack of uniformity, but it will never correct wrongly graded sand, dug from the bank. Modern methods of testing are helpful in setting up standards against which the man in the bank can compare his sands, but a good bank foreman is the only assurance that the sand, as dug, matches the required sample.

Jan 1, 1926

I am much pleased by your presentation of my article and flattered to the extent that the cover design refers to it. Incidentally, as between folks who like to work with words, refer to line 6, second full paragraph, page 773 (August Mining Engineering) Would "for" preceding technological have changed the percentages in lines two and three of the bold-face heading on page 770? The intent was coequality among three, (studies of mankind, of science, and of technological empirics). Thirty-three pct for "man" studies is a pretty big bite for engineering schoolmen; 50 pct they won't even examine, let alone nibble at. Arthur F. Taggart For those of you without a copy of the August issue handy, the sentence referred to read: The plea herein is to make the overall time allotment for studies of mankind coequal with those, for science and technological empirics.... Professor Taggart suggests that insertion of the word "for" would clarify the intent of coequality among three divisions of study: The plea herein is ... for studies of mankind coequal with those for science and (for) technological empirics. Editor.

Jan 1, 1952

By R. E. Gilmore

This paper is a revision of a former paper published in mimeograph form by both the Canadian and American coal classification committees, and is now presented for the purpose of acquainting those interested with the present status of coal classification in Canada. The classification employed for "Customs purposes" is detailed, and the classification schemes from which the customs classification was derived are reviewed and discussed. The activities of the Canadian coal classification committee, namely, the Associate Committee of Coal Classification and Analysis of the National Research Council, is also reviewed. Reserves, Production and Uses of Canadian Coals The total coal resources of North America are estimated to be 69 per cent. of those of the world, and of this portion, the distribution is 52 per cent. for the United States and 17 per cent. for Canada. Accordingly, Canadian coal resources amount to approximately one-third of those of the United States, and one-sixth of those of the world. As for the geographical distribution, the bulk of the known coal deposits are in the extreme eastern and western portions of the country. Employing the usual, more or less loosely defined, designations for the different classes and subclasses of coal, the distribution of the Canadian coal resources, according to provinces, is as follows: Maritime Provinces: Nova Scotia and New Brunswick Bituminous and semibitu- minous coals. Ontario (northern part).............................Lignite. Saskatchewan, (and Manitoba)....................... Lignite. Alberta and British Columbia........................ Lignites, subbituminous, all kinds of bituminous, semibituminous and semianthracite coals. Of the total reserves, roughly 92.5 per cent. is credited to the noncok-ing lower rank subbituninous and lignite groups, the bulk of which are

Jan 1, 1930

By H. T. Mercer

THE composition of steel and the theory of its heat treatment have been so ably discussed elsewhere that it is unnecessary to go into the subject here. The purpose of this paper is to describe briefly the method of treating drill steel at the Copper Range mines, giving some of the troubles encountered and the manner in which they were overcome or corrected. To study the matter properly, it was necessary to devise a system of records that would show the actual underground performance of the drills. To illustrate this system, the records of the Champion mine are used, as it is at this mine that most of the work along these lines has been done. Reports from each drill machine are made daily by the shop and mine, and tables compiled from these reports show the footage drilled, steel broken, drills received and sent out at the shop, drills sharpened, and bits cut off. These data show what each machine or party is doing and whether the miners' supply of drills is kept up to date. There have been times when the supply of drills has been short and time lost by the miner in looking for drills. The daily records show the number and condition of drills on hand at all times. Under the old method of sharpening, the drills were heated in a coke furnace, the proper degree of heat being judged by color. Then they were sharpened in a word drill-sharpening machine, reheated in a second coke furnace where the proper heat was again determined by color, and quenched in water. While this method was fairly successful in the hands of a careful workman and for the solid steel used in the old piston drill machine, the introduction of the faster water machine, using hollow steel, produced changes both underground and in the shop. Much more was expected of the hollow-steel and' hammer-type machine, with its improved method of rotation, but troubles due to breakage, burnt bits, uneven tempering, etc., at once began to appear.

Jan 8, 1920

By William J. Bronkala

Magnetic Separation is a proven means of effectively obtaining purification and/or concentration of mineral products. In addition, magnetic separators are widely used for tramp iron removal in the protection of mineral processing machinery such as crushers, conveyors, mixers, etc. This paper summarizes the various types of magnetic separators available and outlines their basic selection and usage. Current magnetic separator costing is provided for general guidance and estimating.

Jan 1, 1978

By Andrew A. Blair

It is now well known that certain pig-irons give a considerably smaller percentage of sulphur when determined by evolution-methods than when determined by oxidation-methods. The most striking examplcs of such irons are those made either wholly or in large part from New Jersey magnetites containing more or less titanium. It is never safe to use an evolution-method on such iron; for it is quite common that the sulphur result by evolution is only one-half or even one-third as great as that obtained by oxidation. For this reason, evolution-methods should be discarded, except in the analysis of pig-irons known to contain the sulphur in a state of combination from which it is evolved as sulphuretted hydrogen on treatment with hydrochloric acid. A good example of an iron containing, in the residue, sulphur insoluble in hydrochloric acid having come to our attention, it was determined to try to isolate a suspected insoluble sulphide. A large piece of high-silicon gray-forge iron was accordingly selected as the most promising material to work on. This piece was dissolved slowly, through several months, in dilute hydrochloric acid, aided by the electric current, yielding a soft graphitic residue. The object of dissolving a mass of iron, instead of drillings, was to prevent the crushing, by the drill, of any insoluble crystalline compound that might be present. The first step in the preparation was to break up the graphitic material and put it through bolting-cloth of 157 meshes to the linear inch. This was done by crushing the mass under the fingers on the bolting-cloth fastened over the top of a beaker, while a stream of water from a wash-bottle washed the finer portions through the cloth. The suspended matter was allowed to settle. It was then transferred to a platinum

Jan 1, 1902