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By A. W. Gauger

Fox perhaps one hundred years scientists have been engaged in attempts at devising a satisfactory method of classification of coal. During this time many charts, tables and graphs have been proposed, some of which have had considerable merit, but no one system has been found to be applicable to all ranks of coal, nor has any one system received general acceptance. In many of the proposals, water eliminated between room temperature and 105° C. has been regarded as extraneous matter and calculations have been made to the air-dry or water-free basis. Such methods of. calculation do not lend themselves to satisfactory grouping of the high-moisture coals.1,2 A consideration not only of the properties of the high-moisture coals and their behavior on drying but of the generally accepted ideas of the coalification process and the role of water in this process indicates that water is an essential constituent of all coals and therefore should not be neglected. For example, in such low-rank coals as the lignites of the Northern Great Plains' deposits the inherent moisture of the lignite as mined plays a very important part in the physical properties thereof. Freshly mined lignite contains upwards of 30 per cent water and is extremely tough and resistant to shock. Upon exposure to the atmosphere, the lump loses part of its moisture and checks and splits, leaving a friable and broken up residue. So far as we have been able to determine, water is the only thing lost in this process and we are forced to the conclusion that moisture plays an extremely important part in the structural properties of the original lignite. With reference to the coalification process, Mack and Hulett3 pointed out in 1917 the important part that water played therein. They observed that water cannot be removed from peat or coal by pressure alone, but only as the result of chemical reaction, and suggested that peat in its early stages may be largely a hydrosol. Slow chemical changes occur over a long period of time until finally the mass becomes more largely a hydrogel. These views are substantiated to some extent by the experi-

Jan 1, 1932

By H. Foster Bain

In the preparation of this series of books it was considered particularly appropriate to include this work. Gunther was one of the younger men who was associated with Colonel Mudd in the finding and development of ore deposits. Supported by Mudd, Gunther undertook a systematic survey of the sources of copper of ancient Europe. This survey resulted in the rediscovery of the deposits now worked by the Cyprus Mines Corporation for which Gunther was, until shortly before his death, the resident manager. In finding and developing these mines, Gunther applied the methods and data embodied in this book and proved their usefulness. It is believed that other young engineers may profit similarly. In presenting a new edition, the form and substance of this work have been preserved and no changes have been made in any direct statement of the original author. Individual illustrations, paragraphs and mine descriptions appearing in the first edition have been omitted in order to permit introduction of new material. The latter has been chosen so as to present a somewhat more balanced picture of the mining industry as it now exists. The new material relates largely to the so-called porphyry coppers, to mines in Canada, Rhodesia, Alaska, and a number in the United States that have become important since the book was first written. The new material was prepared by Mr. Russell C. Fleming, using the best that had been published and items of which he had personal knowledge or had obtained by correspondence with men familiar with the deposit described. Whenever possible the description used has been submitted to the original author for correction. In a number of instances

Jan 1, 1932

Jan 1, 1932

Jan 1, 1932

By Perry Harrison

THE increased use of sintering for the beneficiation of iron ores and the reclaiming of flue dust creates a lively interest in sintering costs and, economics. The character of material sintered and geographical location of plants so radically alter sintering costs and economics that it is well to understand at least the basic elements which control such changes. The following cost factors are believed to be roughly approximated for large-scale Dwight-Lloyd 'continuously operated sinter-machine installations located anywhere. PER CRUDE TON Labor, supplies and repairs 0.15 Power 6.5¢ X kw-hr. rate ? Plant overhead and administration 0.05 Depreciation per ton annual capacity 0.05 Fuel: 6 per cent coke breeze or equivalent minimum ? 1 per cent coke breeze additional for each 5 per cent free and combined water in ore or dust ? Ignition distillate at 0.6 gal. per ton ? PER SINTER TON Royalty on Ore 0.10 Royalty on Flue Dust 0.15 PER CRUDE TON "Winter expense"; i. z., the cost of the five months enforced idle . period for plants tied in to Great Lakes transportation season 0.03 Using the foregoing data, it is possible to roughly approximate the cost of efficient sintering at any location for. any ore, viz:

Jan 1, 1932

Jan 1, 1932

Forty-three years ago a record for low cost was made at the Spanish mine, in Nevada county, California. In 22 days of September, 1887, there was mined 2796 tons of ore at a cost of 37.5 cents per ton, of which 32.4 cents was for labor and 5.1 cents for supplies. The mill treated this ore for 23 cents per ton, of which 12.3 cents was for labor and 10.7 cents for supplies. Thus the total operating cost was 60.5 cents per ton. The yield was $1.16 in gold per ton, leaving a profit of 56 cents per ton, or 48 per cent of the yield. The mine was an open-cut in a schist formation on a hillside and the work was done by Chinese laborers that were paid $1.40 per shift. The ore was soft, and could be ground effectively in four Hunting- ton mills, supplemented by silvered amalgamating plates.* The engineer in charge was F. W. Bradley, a student from the University of California. As has been indicated, the conditions were unusually favorable in respect of softness of ore, accessibility to the mill, metallurgic simplicity, with cheap labor and power, but even at that the results were so remark- able as to attract general attention, which, as might be expected, was magnified, for advertising purposes, by the manufacturers of the Huntington mill, the firm of Parke & Lacy, at San Francisco. The record made at the Spanish mine therefore found its way into many textbooks on mining published at that time. The editor of the 'Mining and Scientific Press'† (at that date, Charles G. Yale) evidently took a warm interest in. the

Jan 1, 1932

By Charles Burgess

THE improvement, in the quality of cast iron by means of alloy additions has been a metallurgical accomplishment of recent years. Work in this field has shown that chromium is one of the most effective of such additions but, in general, the influence of chromium has been studied only in. connection with other alloying additions, with irons other than foundry irons, or with relatively high percentages of chromium. The present study was initiated for the purpose of determining the influence of small additions of chromium (0.25 to 1.00 per cent) on the quality and resultant properties of cast irons of various foundry grades. The effect of small chromium additions on cast iron was investigated with particular reference to casting characteristics, hardness vs. section, strength, machinability, heat resistance and structure. MATERIAL TESTED Three separate types of cast iron were investigated as to the effect of small chromium additions. The first series of these irons was prepared from remelted foundry cast iron at the Union Carbide and Carbon Research Laboratories, and the other two -series consisted of cupola melts made under usual operating conditions. The first series was made by melting 30-lb. charges of foundry scrap iron containing - 2.86 per cent carbon, 2.72 silicon, 0.50 manganese, 0.062 sulfur and 0.794 phosphorus in a carbon resistance furnace. The chromium was added as high-carbon ferrochrome just before pouring. The irons were cast at approximately 1250° C. (2282° F.). The analysis and physical properties of these irons are given in Table 1, test 1. The second set of cast irons was made in a cupola in accordance with normal practice, 'the charge containing approximately 42 per cent steel scrap and the chromium additions being made to the ladle. Analysis and tests of these heats are shown In Table 1, test 2. A small amount of copper was present in heat C of this series.

Jan 1, 1932

By Maurice Ewing, L. Don Leet

The most important quantitative method in seismic prospecting by refraction shooting is the method of profiles. A profile is established by firing a series of charges at various points along a straight line which terminates at the seismograph. The same data are obtained by repeatedly firing charges at one place and recording at a series of stations along the line of the profile. The quantities which are measured are the distance x from each firing position to the seismograph and the time t required for the first disturbance from each explosion to travel to the seismograph. These data are used in plotting the familiar time-distance graph. The only time-distance graphs that will be considered here are those obtained in localities where the velocity of propagation depends solely on the depth beneath the surface; that is, where there is no slope in the subsurface. The essential calculation to be made from such a time-distance graph is the determination of P(x), the maximum depth of penetration of a disturbance coming to the seismograph from a firing point at the distance x from the instrument. If the time-distance graph consists of a series of straight lines, as is often the case, the penetration P(x) can be calculated by means of formulas which appear in almost every description of seismic prospecting.' Until the present, however, the only formula that has been available for calculating P(x) for time-distance graphs which are smooth curves is one which requires an arbitrary assumption regarding the law of velocity increase with depth.2 The practice in these cases has been to approximate the curve by means of a number of straight lines and then to apply the ordinary straight-line formulas. This method clearly can yield accurate results only when a sufficiently large number of straight lines is used. The labor of computation increases rapidly when the number of lines is increased, so too few lines often are used. Further than that, there is a strong tendency to overlook the approximate nature

Jan 1, 1932

By W. N. Logan

WHAT is mineral wool? This question is frequently asked by those unacquainted with its manufacture. The word "mineral" suggests that it is of mineral origin; the word "wool" suggests that it is of animal origin; but the only similarities it has to wool are its fibrous character and its white fleecyness. Mineral wool is a fiber produced by melting rock to a glasslike condition and blowing the glass into fine white, wool-like threads. A -number of the products fabricated from-mineral wool are used for some form of insulation, but mineral wool is adaptable to many other uses. It is used in the manufacture-of pipe covering designed to with; stand the high temperatures produced in steam pipes. In a similar form of insulation it is used to cover boilers and furnaces. It is used in ,the fabrication of upholstery tow for sofas and car seats: In acoustics it has many uses, such as acoustifibroblock, which is used in floors to destroy sound and vibration, and acoustic mat, which is used under carpets to destroy sound. In the insulation of houses, loose wool and granulated wool are used beneath attic floors and between the studding in frame buildings to prevent the escape of heat in winter and the entrance of heat in summer. Mineral wool is used also in fabrication of linofelt, which is a quilted form of insulation; in fibrofelt, which is an insulating board; in the fabrication of lith, which is an insulating block; in anti-fibroblock ,which is used in insulation and refrigeration; in flexfelt; in loose wool; in pressed block; in heavy oiled wool; in dark oiled block; and for many other purposes. The materials used in the manufacture of mineral wool are of two kinds. The first is a rock which contains silt, clay and silica, with smaller amounts of lime and magnesia. The second is a more highly calcareous rock which may carry a small amount of magnesia. The latter is used as flux to assist in the melting of the former. The relative proportion of the alumina-iron-silica content to the lime-magnesia content is normally as fifty to fifty but a considerable range is possible.

Jan 1, 1932

By E. M. Wise

THE practice of dentistry, particularly the construction of artificial dentures and "bridges," involves a unique and difficult application of the precious-metal alloys. Appliances used in the mouth are continuously exposed to corrosive agencies which can hardly be described as mild, and must remain free from tarnish and be substantially immune to corrosion. Limitations with respect to space and weight demand high physical properties, while complexity of form requires ease of working. The high corrosion resistance required necessitates the use of alloys of high precious metal content. The usual expedient of resorting to mechanical working to produce the requisite strength and stiffness cannot be utilized because of the frequency of annealing and soldering operations. To meet these difficult conditions manufacturers of dental goods were early led, unknowingly perhaps, to the production of precipitation-hardening or temperable alloys. The excellent properties of iridium-platinum may have suggested the addition of platinum metals to the conventional gold-silver-copper alloys to produce greater strength and hardness. It was found that such quarternary alloys retained their high physical properties after passing through the usual soldering process; i, e., heating to 7500 to 8000 C. and cooling naturally in the air. Later it was discovered that they could be softened and rendered more ductile by heating to the same temperature and quenching, in water. These early examples of precipitation hardening, for years the common knowledge, of dental practitioners and laboratory technicians, escaped the attention of the scientific world and discovery of the transformation which was responsible for this hardening was discovered by the Russian investigators of the system Au-Cu, Kurnakow, Schemtschushny and Zasedatelev,(1) § although the optimum conditions for securing good properties in aged alloys were not given attention.

Jan 1, 1932

President MRS. FREDERICK LAIST 24 Tompkins Road Scarsdale, N. Y. First Vice-president MRS. LOUIS D. HUNTOON Pleasantville New York Second Vice-president MRS. REED W. HYDE 84 Mountain Avenue Summit, N. J. Third Vice-president MISS MADELINE P. STONE 49 West 11th St. New York, N. Y. Fourth Vice-president MRS. JOHN J. LINCOLN Elkhorn, McDowell Co. West Virginia

Jan 1, 1932

Jan 1, 1932

Jan 1, 1932

GENTLEMEN : It is my privilege to transmit herewith the reports for the calendar year 1932 of your Treasurer and the Chairmen of the following Standing Committees: Finance, Admissions, Membership, Papers and Publications, Library, and Mining and Metallurgy. To these reports you are referred for additional details of the year's activities. Finances.-Continuation of depressed conditions in the mining industry (in common with other industries) caused the income of the Institute to decline from $168,274 in 1931 to $138,331. However, economies were effected so as to reduce expenditures from $171,198 to $135,977. As a consequence the net result of the operations for the year was a-surplus of income amounting to $2,354 compared with a deficit of $2,924 in 1931. This gratifying result is accounted for in large measure by the foresight of the Finance Committee in anticipating a substantial decline in income and preparing the budget accordingly. Incidentally, the tentative budget for 1933 has been balanced at $125,000.

Jan 1, 1932

Trans No. Place Date Vol. 1. Wilkes-Barre, Pa. May, '71 1 2. Bethlehem, Pa. Aug., '71 1 3. Troy, N. Nov., '71 1 4. Philadelphia, Pa. Feb., '72.. 1 5. New York, N. Y. May, '72 1 6. Pittsburgh, Pa. Oct., '72 1 7. Boston, Mass. Feb., '73 1 8. Philadelphia, Pa. May, '73 2 9. Easton, Pa. Oct., '73 2 10. New York N. Y. Feb., '74 2 11. St. Louis, Mo. May, '74 3 12. Hazleton, Pa. Oct., '74.. 3 13. New Haven, Conn. Feb., '75 3 14. Dover, N. J. May, '75 4 15. Cleveland, Ohio Oct., '75 4 16. Washington, D. C. Feb., '76 4 17. Philadelphia, Pa. June, '76 5 18. Philadelphia, Pa. Oct., '76 5

Jan 1, 1932

By L. B. Slichter

After statement of the principles of similitude which apply to electromagnetic modeling, charts showing the inductive response of conducting spheres as dependent upon frequency, conductivity, and size are exhibited in this paper. The shape of the curve which relates intensity of response to frequency is significant in indicating the advisability of low frequencies in the exploration for conducting bodies, when consistent with the securing of a large percentage of the ideally possible response. Comparisons of theoretical response and that observed with models are shown, and relationships with the subject of applied electromagnetic prospecting are indicated. Maxwell Field Equations The Maxwell field equations summarize the physical laws that govern electrical field phenomena; they are the basis for the solution of electromagnetic problems. These concise equations, with adequately formulated boundary conditions, specify the complete electrical condition of continuous media, and the development of their solution amounts merely to a more convenient re-expression of phenomena already completely described. Thus, the immediate content of the field equations themselves is sufficient and sometimes convenient for the treating of certain questions (such as those relating to electromagnetic models) which are independent of the special factors of geometry, or the nature of an impressed field. The four Maxwell field equations are written below, in c.g.s. gaussian units: curl E = -B/c [21 div eE = 4pp [31 div B = 0 [41

Jan 1, 1932

Abel, Charles Edwin, Student, Univ. of California Los Angeles, Cal. '81 Ames, Marshall B., Blaine-Republic Co Republic, Wash. "81 Anderson, Norman John, Student, South Dakota School of Mines Rapid City, S. D. '82 Angst, Robert A., Jr., Student, Michigan College of Min. & Tech Houghton, Mich. '82 Apgar, James William, Student, Lafayette College Easton, Pa. '83 Armstrong, John R. Box 274, Neosho, Mo. '81 Armstrong, Robert H., Student, Lafayette College Easton, Pa. '81 Arnot, Paul H. 608 S. Acacia St., Compton, Cal. '81 Asel, Philip R., Student, Colorado. School of Mines Golden, Colo. '82 Atkins, William Robert, Student, Michigan College of Min. & Tech Houghton, Mich. '82 Augenthaler, Robert L., Student, New Mexico School of Mines Socorro, N. M. '82 Augustine, Robert W., Student, Alaska School of Mines College, Alaska. '82. Avery, Eugene A., Student, Montana School of Mines Butte, Mont. '82 Babcock, Norwood N., Student, South Dakota School of Mines Rapid City, S. D. '82 Baer, Jerome S., Student, Michigan College of Min. & Tech Houghton, Mich. '81 Baker, Robert C., Student, Pennsylvania State College.. 112 E. Beaver Ave., State College, Pa. '82 Baldwin, William C., Student, Univ. of Illinois Urban, III. '81

Jan 1, 1932

By Hallan N. Marsh, Bruce H. Robinson

It is generally believed that the flowing of wells through tubing instead of casing results in the conservation of gas. It is further believed that use of tubing prolongs the flowing life of a well and results in greater ultimate recovery, provided either that there are no adjacent wells, or that any adjacent wells are similarly operated. Recent experience in the flowing of Buckbee zone wells at Santa Fe Springs has not only substantiated both of these beliefs but has led to the further conclusion that the use of tubing results in a greater cumulative flowing production, ' even in a highly competitive field like Santa Fe Springs, where the wells concerned are closely offset by wells of both the same and other companies flowing through casing. Further, gas-oil ratio has been so reduced that greater ultimate recovery can be expected. In the belief that such would be the case, the majority of the Buckbee zone wells of one company were brought in through tubing, but enough wells were flowed through casing to form the basis for a comparison. For the purpose of this comparison, wells with flow strings 2½ or 3-in. dia. are designated as tubed wells, while those having flow strings larger than 3-in. dia. are designated as untubed wells. Casing used was mostly of 5 ¾-in. dia., the remainder being of 4¾-in. dia. There were 15 tubed wells and 8 untubed wells and they were scattered over the field in such a way that neither group appears to have any distinct advantage as regards location. Locations of all wells involved in the comparison are shown on Fig. 1. All the Buckbee sand wells of the company are included in the average production curves, with the exception of eight that were unsatisfactory for reasons other than the method of flowing. Findings 1. Buckbee sand wells flowing through casing larger than 3 in. had an average maximum production rate of 4670 bbl. per day, while wells flowed through straight tubing or 3-in. casing had an average maximum production of only 3300 bbl. per day. (See Fig. 2.)

Jan 1, 1932

In our sessions devoted to geophysical prospecting, the greater part of the time heretofore has been given to the presentation of theoretical subjects or highly technical details by specialists directly engaged in the development and perfection of the various methods. This was necessarily so, for we wanted such information available for the benefit of other workers and for our members who were anxious to gain a reliable understanding of the principles involved, to enable them to form an opinion of the adaptability of this new technique to their special problems. The methods have now been actively applied by many reliable organizations for several years and in this period there has been opportunity for operating mining men, engineers and geologists to appraise them. We therefore felt that it would be desirable at this meeting to give some time to interchange of opinion concerning results from actual cases. Consequently, the Committee on Geophysical Methods of Pros pecting sent out letters of inquiry to numerous mining people, asking for frank statements of opinion based on results from geophysical surveys at their properties. We have received many replies, among which 30 or more are of specific interest. On the whole, the point of view is remarkably uniform. Except for one or two who were, perhaps, a bit irritated, the operating men who have replied consider the methods to be capable of yielding valuable information when suitable conditions exist. Their attitude is definitely one of tolerance and of confidence in the integrity and sincerity of the outstanding workers. There is, however, a very general feeling that the chances of attaining positive and trustworthy results are small unless the work is directed by, or at least carried on with the close cooperation of, a geologist or mining man who is thoroughly familiar with the local geologic and mineralogic conditions and with the relations of the orebodies to rocks and structure. From certain comments, I am inclined to think that some operators are not greatly impressed with the cheapness of the work. Probably they are not attaching much weight to cost per acre, but are thinking primarily of total cost in terms of significant results obtained. It is

Jan 1, 1932