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By R. H. Winn

A method for the selection of the most suitable corrosion inhibitor for a particular system is given. The method involves the evaluation of surface passivity by means of copper ion displacement after the metal surface has been subjected to the corrosive atmosphere. The application of the method to the selection of suitable inhibitors for use in producing wells is described. Correlation with recognized laboratory tests has beet1 found to be good within the limitations of the test. The use of the test to evaluate inhibitor persistencc is described. INTRODUCTION Corrosion as it is associated with the industry shows wide variations in its qualitative as well as its quantitative aspects. This complicates the work of the corrosion engineer. In the past few years the efforts of the corrosion engineer have been further taxed by the large numbers of products being marketed as corrosion inhibitors by various manufacturers. These products are submitted to him together with a limited amount of data to support their use as inhibitors. The data are usually authentic and reliable yet all too often when these products are applied to an actual corrosive system the results are disappointing due to the ineffectiveness of the inhibitor and the corrosive system. The corrosion engineer must select a comparatively limited number of inhibitors for field trial from the large number available. The selection is usually made on the basis of a standardized laboratory test such as that adopted by the National Association of Corrosion Engineers or by field experience in an area; however, testing of this type is discouraging on large numbers of compounds, particularly in view of the specificity of environment. It has been an object of this work to devise a method which will allow the corrosion engineer to select the best inhibitor for a specific environment under field conditions. The test would of necessity be rapid and inexpensive. It would preferably eliminate the need for expensive and delicate instruments. STATEMENT OF THEORY The test as developed makes use of the fact that metal ions will be displaced from solution by metals having a more positive electrode potential. Thus, if an active iron surface is exposed to a solution of a copper salt, free copper will plate spontaneously on the iron surface as it is displaced from the salt solution by iron ions. If the iron surface is passified, as by coating with an insulating-type organic corrosion inhibitor, it is no longer capable of displacing the copper ions due to its own limited ionization. The result will be a change in the amount of copper plated upon exposure to a neutral copper salt solution. In practice it has been found possible to measure the magnitude of the alteration of the cell potential by determining the copper deposited on a standard iron surface under controlled conditions. This means that, as the film builds up, the resulting shift in the electrode potential tends to cause the iron surface to act more like a noble metal, resulting in a reduction in the cell potential to a point that copper will no longer plate spontaneously. Obviously, the salts of other metals such as silver, gold or platinum might be used for this operation; however, copper was selected because of the color difference of the plate, the comparatively low cost of copper salts and the ease of evaluation of the plated copper. Furthermore, its high cell potential provides a substantial driving energy. The determination of the copper is readily done colorimetrically by dissolving it in 5 per cent ammonium hydroxide solution containing 2 per cent potassium per-sulfate. The blue color of the copper ammonic complex ion so developed may be compared with standards prepared by dissolving known quantities of copper powder in the same reagent. In routine screening it is seldom desirable to determine the amount of copper plated. It is usually more important to determine the concentration of inhibitor required to prevent the plating of copper.

By Sallie McCabe Johnson

LIFE IN RUSSIA for the foreign woman is hard. It is up to her whether her days are spent in tearful longing for ironic or whether she :hakes the real effort to ferret out the interesting or amusing side of such exasperating conditions as ooh a Russian can conjure. So to begin Discard all promises.. This is perhaps the most difficult thins- to learn but promises in Russia are nut what they are at home. There are many reasons for ibis, sonic good and some bad but whatever the reason. the fact remains that they are usually worthless- as each of us must slowly learn In, disappointment after disappointment. Also we must learn that we cannot expect to get or to do a certain thing just because someone else has done so. What we did yesterday perhaps cannot be dune today. What we purchased air hour ago, oxen ten minutes ago- we cannot purchase now. What our neighbor did this morning we cannot do this afternoon. Changes arc continuous. Every person's experience is different from that of another aid this in a great measure accounts for the conflicting stories brought horns. In a land of chaos we live only from hour to hour and this is one of the exceedingly exasperating conditions to face. When I wished to visit Leningrad, an overnight nip from Moscow, more than a week's lime w as required to obtain a ticket, vi en through the efficiency of lntourist: alone I might have spent a month at it. Each day

Jan 1, 1932

By C. H. Benedict

Largest and most important of the milling plants under construction during the year is the Morenci plant of the Phelps Dodge Corp., in Arizona, where plans are being rushed for production in 1942. Grate mills will be used for fine-grinding, and in the pilot plant, classifiers of the spiral type have the preference for the closed- circuit work. The flotation units will be chiefly of the pneumatic type, with some mechanical units as auxiliaries. The Fagergren, Pan American, and Agitair machines were left in the competition as the year closed. If the absence of European markets for finished products has dislocated the mining industry, fortunately the lack of raw materials required in the beneficiation of ores has not been serious. except possibly as to the inability to import flint grinding pebbles. Some of the less important gold mines still use pebbles for grinding as is also the practice in the comminution of nonmetallics used in various industries. T the Calumet & Hecla in the Lake A Superior copper district pebbles have been used exclusively in open- circuit grinding in the Hardinge mills treating the

Jan 1, 1941

By J. G. Hadley

IN THE early stages of the depression the Utah Copper Co. realized that an unemployment problem would he created which demanded an intelligent and sympathetic solution. The company recognized that as many men as possible must be kept at work on a basis which would ultimately permit of the most efficient reabsorption of displaced labor. The company therefore determined to distribute available work among the greatest number of men and to that end adopted a system of rotating employees on a part-time basis. An employer requires a certain number of days' or shifts' work during the month. Obviously one employee working thirty days or shifts a month is equal to two employees each working fifteen. In principle, therefore, where two employees equally fitted to do certain work are available the work could be divided between them on an equitable basis and twice as many persons would benefit. A rotation plan on this basis was adopted by the Utah Copper, Co. on Jan. 30, 1930. Some variations of the orig¬inal plan have been made from time to time, the reasons for which will be discussed.

Jan 1, 1932

By W. M. Myers

Certain minerals possess inherent color and other properties that make them suitable for the pigmentation of paints, mortar, plaster, concrete, face brick, and other materials. Their production is one of the most ancient of mineral industries and their use by primitive man is well known. These natural pigments have some economic factors in their favor, particularly wide geographic distribution, low cost of production, ease of preparation, chemical stability, and permanence in use so that they continue to form the basis of a small but useful industry. When used in paints such pigments act as a filler and supply body and opacity in addition to color. Natural mineral pigments are prepared for the market by the comparatively simple operations of washing, grinding, blending, and calcining. Any one, or all of these processes may be applied to a single pigment. The development of synthetic pigments and the use of by- product materials have introduced competition with the products of nature and are having a growing influence on the economic position of the mined minerals.

Jan 1, 1949

By E. J. Lintner

CLAY mining in the 'United States is by no means a small industry for approximately ten million tons of shale and clay are recovered yearly. The bulk of this tonnage enters into the manufacture of paving, building and refractory brick, draintile, pots, sewer pipe, stoneware, and wall and floor tile. This group of manufactures is commonly known as the heavy clay products industry. The winning of the raw materials for this industry constitutes merely a step in the manufacturing process because the manufacturer usually owns and operates his own source of supply. The mining of kaolin and the whiteware and chinaware claps, however, is usually a separate industry.

Jan 1, 1936

By E. J. KENNEDY

FEBRUARY 15-18 will be the outstanding dates of the month for members of the A. I. M. E., for then the 141st Meeting of the Institute is to be held in the Engineering Societies Building, at New York. What with 41 technical sessions, the Annual Business Meeting at 4 o'clock Tuesday afternoon,, two sessions of the Section and Division delegates, minor committee meetings, and the many luncheons and dinners, the Dinner-Smoker, Informal Dance, President's Reception and the Dinner-Dance, the opportunity will be limited to do- more-than cast sheep's eyes at New York's other multitudinous attrac¬tions until the meeting is over. The technical program is diverse but well organized. The sessions are almost equally divided among the four days, with ten on Monday, Tuesday, and Wednesday, and 11 on Thursday. The meeting opens Monday morning with registration. Be sure to attend to this detail. Failure to do so may have its repercussions at the meeting and throughout the year.

Jan 1, 1932

Trans. No. Place Date Vol. Page 1. Wilkes-Barre Pa......May.71 1 3 2. Bethlehem, Pa.........Aug., '71 I 10 3. Troy, N.Y............Nov..: 71 1 13 4. Philadelphia, Pa........Feb., 72.. 1 17 5. New York. N. Y.*......May, '72.. 1 20 6. Pittsburgh. Pa.........Oct..' 72.. 1 25 7. Boston, Mesa..........Feb., '73.. 1 28 8. Philadelhia, Pa.*......May, '73.. 2 3 9. Easton, is............Oct..' 73.. 2 7 10. New York, N. Y.......Feb..' 74 . . 2 11 11. St. Louie. Mo.*........May,' 74 . . 3 3 12. Hazleton, Pa...........Oct., '74.. 3 8 13. New Haven Conn......Feb., '75.. 3 15 14. Dover,N.J.*..........May, 75.. 4 3 15. Cleveland,O...........Oct. 75. 4 0 16. Washington D. C......Feb.'' 76.: 4 18 17. philadelphia, Pa.......June,: 76.. 5 3 18. Philadelphia Pa........Oct 76.. 5 19 19. New York, N. Y.......Feb: '77.. 5 27 20. Wilkes-Barre. Pa.*.....Mag :77.. 0 3 21. Amenia N. Y..........Oct. 77.. 6 10 22. Philadeiphia Pa........Feb.;' 78. . 6 18 23. Chattanooga' Term.*. . . May' 78. . 7 3 24. Lake George: N. Y....: Oct. 78. . 7 103 25. Baltimore, Md.*.......Feb:' 79.. 7 217 26. ~ittsburgi, Pa.........~a;' 79.. 6 3 27. Montreal, Canada......~ept.;' 79.. 8 121 28. New York, N. Y.*......Feb., '80.. 8 275 29. Lake Superior, Mich....Aug., '80. . 9 1 30. Philadelphia, Pa.*......Feb., '81. 9 275 31. Staunton, Va..........May, '81. .10 1 32. Harrisburg, Pa.........Oct.. '81..10 119 33. Washington, I). C.*....Feb., '82. . 10 226 34. Denver. Colo..........Aug.. '82. . ll 1 35. Boston. Mass.*.........Feb.. '83..11 217 38. Roanoke, Va...........June, '83.. 12 3 37. Troy, N. Y...........Oct.. '83. .12 175 38. Cincinnati. O.*.... Feb, '84..12 4 39. Chicago Ill............May, '84. . 13 1 40. philadelphia, Pa........Sept., '84. . 13 285 41. New York, N. Y.*......Feb., '85. . 13 586 42. Chattanooga, Tenn.....May, '85..14 1 43. Halifax, N. S..........Sept., '85.. 14 307 44. Pittsburgh, Pa.*........Feb.. '86 . . 14 587 45. Bethlehem. Pa.........May, '86 .. 15 Ixiii. 46. St. Louis, Mo..........Oct, 86.. 15 Ixx. 47. Scranton, Pa.*.........Feb.', '87. . 15 lxxvi 48. Utah and Montana.....July '87.. 16 xvii. 49. Duluth, Minn...........July' '87. -16 xxiv. 50. Boston. Mass.*.........Feb.: '88. . 16 xxviii. 51. Birmingham, Ala.......May, '88. .17 xix. 52. Buffalo N. Y..........Oct. '88.. 17 xxiv. 53. New york, N.Y........feb.' ;89 . . 17 xxxi. 54. Colorado..............June' 89 . . 18 xvii. 55. Ottawa, Canada........Oct., 89. . 18 xxiv. 56. Washington, I). C.*. . . Feb. 90. .18 xxx. 57. New York, N. Y........sept:, '93. .19 vii. 58. New York, N. Y.*......Feb. '91. . 19 xxv. 59. Cleveland, O.......... June, :91 . .a xvi. 60. Glen Summit, Pa.......Oct, 111. . 20 lxi. 61. Baltimore, Md.*.......Feb.: '92. .21 xix. 62. Plattsburg, N. Y.......June, '02. . 21 xxxiii. 03. Reading. Pa...........Oct., :92. .21 xliv. 64. Montreal. Canada*.....Feb. 93..21 65. Chicago, Ill............aug.: '93..22 XI. 66. Virginia Reach. Va.*. ...Feb., '04. .24 xwl. 67. Bridgeport Coon.......Oct., '94..24 xxx?. 08. Florida ...'............Mar., '95. .25 xix 69 Atlanta. Ga......... Oct 95. 25 xi 70. Pittsburgh. Pa.*........Feb., '96.. 26 xvii. Trans. No. Place Date Vol. Page 71. Colorado..............Sept. '96. .26 xxix. 72. Chicago, Ill............Feb.. "97.. 27 xvii. 73. Lake Superior..........July '97. .27 xxx. 74. Atlantic City, N. J.*. ..Feb.: :98. .28 xvii. 75. Buffalo N. Y..........Oct. 08. .28 XXXVI. 76. New York,N. Y.*......Feb.: '99. .29 xvii. 77. California.............Sept., ;99. . 29 xlix. 78. Washington, D. C.*.....Feb., 00. .30 xix. 79. Canada...............Aug.. '00. .30 xlv. 80. Richmond. Va.*........Feb.. '01. . 31 xix. 81. Mexico................Nov..'01.. 32 cxviii. 82. Philadelphia Pa. $......May, :02. . 33 xxxv. 83. New Haven, Conn......Oct.. 02.. 33 xlvii. 84. Albany N. Y.*........Feb '03. .34 xxiii. 85. New York, N. Y........Oct.': '03. .34 xi. 86. Atlantic City. N. J.*....Feb., '04. .35 XXIII. 87. Lake Superior..........Sept.'04. .35 dii. 88. Washington. D. C......May' '05. .36 xlii. 89. British Columbia.......July, '05. . 36 90. Bethlehem. Pa.........Feb. '06. .37 xli. 91. London, England.......July: '06. .37 xlviii. 92. New York, N. Y........April, '07. . 38 lii. 93. Toronto, Canada.......July. '07. .38 lix. 94. New York, N. Y........Feb., :08. .39 xli. 95. Chattanooga, Tenn.....Oct.. 08..39 xlviii. 06. New Haven Conn......Feb. '09. .40 xli. 97. Spokane,Wash.........Sept:.'09. .40 xlviii. 98. Pittsburgh, Pa.........Mar.,'10. .41 xxxviii. 99. Canal Zone............Nov.,'10. .41 dv. 100. Wilkes-Barre, Pa.......June. ' 11. . 42 xxxiv. 101. San Francisco, Cal......Oct.. '11..42 xliv. 102. New York. N. Y.*......Feb 12. .43 Ixxvii. 103. Cleveland, Ohio........0ct;' '12.. 44 wii. 104. New York, N. Y.*......Feb.. '13. .45 xv. 105. Butte, Mont...........Aug., '13. .46 ?' 108. New York, N. Y........Oct., 13..47 vii 107. New York. N. Y.*......Feb.. '14..48 xv. 108 Salt Lake City. Otah Aug. :l. 49 5: 109. Pittsburgh, Pa.........Oct., 14. .50 vii. 110. New York, N. Y.*......Feb., '15. .51 xvi. 111. San Francisco, Cal......Sept., '15. .52 xii. 112. New York,N. Y.*......Feb., '16..54 xvi. 1 Arizona...............Sept.,'l6. .55 VII 114. New York, N. Y.*......Feb., '17: .56 vii. 115. St. Louis, Mo..........Oct.. '17..57 vii. 116. NewYork,N. Y.*......Feb.. '18..59 xvii 117. Colorado.....:........Sept.,'18. .60 vii. 118. Milwaukee, Wis........Oct.. '18. .60 x:!: 119. NewYork,N. Y.*......Feb., '19..61 xi. 120. Chicago...............Sept.,' l9.. 62 VII. 121. New York, N. T.*......Feb., '20..63 ix. 122. Lake Superior District. .Aug., '20.. 66 ix. 123. New York, N. Y.*......Feb., '21. .66 xiii. 124. Wilkes-Barre, Pa...... Sept.. : 21.. 66 xix. 125. New York, N. Y.*......Feb., 22. .67 ix. 126. San Francisco. Cal......Sept.,:22. .68 xxix. 127. New York, N.Y.*.....Feb., 23. .69 xxix 128. Canada...............Aug., '23. .69 xxxv! 128.129. New York, N. Y.*......Feb., ;24. .70 xxxi. 130. Birmingham, Ala.......Oct. 24. .71 xxxiii 131. NewYork.N Y.*......Feb.: '25.. 71 xxxviii. 132. 131.Salt Lake City, Utah .. .Sept., '25. .73 xvi 133. New York, N. Y.*......Feb., '26. .73 xxii. 134. Pittsburgh Pa ....... Oct.. '26. .74 xv. 135. New York,' N. Y.*............Feb., '27. .75 x::: 135.136. NewYork,N. Y.*......Feb., '28..76 104 137 NewYork.N. Y.*......Feb., '29. .291 116 138.San FranciscoYork,N.Y. Cal..........Oct. 29..308 406 139. New York, N. Y.*...Feb., '30..30H 1321

Jan 1, 1930

By Edward W. Parker

I. INTRODUCTION. AT the Seventy-sixth meeting of the Institute, held in New York, N. Y., February, 1899, I presented a, paper on this subject entitled, Coal-Cutting Machinery,' which has become somewhat out of date, in view of the decade's development in this feature of the coal-minim industry. It should be explained that the present paper is limited to the use of mining-machines in bituminous mines. Practically all of the anthracite mined is ?shot from the solid," no undercutting being done. Anthracite-mining is therefore not considered in the statistics or other references. The statistical record as compiled by the United States Geological Survey shows that in 1898, the year preceding the presentation of my former paper, there were 32,413,144 short tons of coal undercut by the use of machines. In 1907 the machine-mined coal-product amounted to 138,547,823 short tons. In sympathy with the general decrease in coal-production during 1908, the output of machine-mined coal decreased to 123,183,334 short tons, but the proportion of machine-mined coal to the total output, nevertheless, showed an increase, from 35.1 per cent in 1907 to 37 per cent in 1908. In 1898 only 19.5 per cent. of the total product was undercut by the use of machines. The number of undercutting-machines in use in the bituminous mines of the United States has increased from 2,622 in 1898 to 11,144 in 1907, and to 11,569 in 1908. The total production of bituminous coal in the United States in 1908 was almost exactly double that of 1898, while the machine- * Published by permission of the Director of the U. S. Geological Survey. 1 Trans.. xxix.. 400 to 4,59 (1899).

Sep 1, 1910

By Hugh D. Pallister, Richard W. Smith

The Alabama flake-graphite industry has flourished only in times of war when importations of foreign graphite for crucible use have been greatly curtailed or cut off. World War I was a boom period and in 1918 some 30 plants produced 7,795,475 Ib. of flake graphite. The industry languished following the war and no graphite was produced from 1929 to 1939. The Federal Bureau of Mines began investigating the Alabama graphite deposits in 1940 and worked out modern recovery methods that were applied to production during part of World War 11. A prospecting program disclosed reserves of over 25 million tons of graphtic schists. In 1942 the War Production Board authorized the enlargement of the only plant then producing flake graphite and the construction of two new plants. Production of flake graphite from these three plants in 1943 is estimated at 8,100,000 lb. Increased imports from Madagascar late in 1943 shut down one of the new plants and curtailed production at the other. Alabama flake graphite has not yet been able to compete with Madagascar graphite for use in the manufacture of any but small graphite crucibles. The future of the industry must depend on meeting the higher carbon content demanded for other uses. Introduction The flake-graphite deposits of Alabama are confined to a narrow belt extending for about 60 miles southwest from the northeast corner of Clay County across Coosa County to the edge of the Coastal Plain in Chilton County (Fig. I). The continuity of the beds is broken by a 10-mile gap between Millerville in Clay County and Goodwater in Coosa County. The Clay County beds extend about 27 miles northwest of this gap, with a width of 3 to 4 miles near Millerville and of less than a mile at the northeast end. The Coosa-Chilton are? is about 33 miles long with a fairly consistent width of 2 to 3 miles. Geologically the graphite belt lies near the northeast boundary of the outcrop of metamorphic rocks of the Ashland series, a complex group of intensely folded and faulted beds of pre-Cambrian age composed mostly of quartz-mica schist, in which the mica is predominantly muscovite; garnet-mica schist, in which biotite is more common; and hornblende schist. Flake graphite is found in commercial quantities only in the quartz-mica schist. The best graphite, both in quantity and quality, is found in schist cut by numerous small pegmatite stringers along the planes of the schistosity. The pegmatites themselves contain little graphite, but the adjacent country rock is normally rich. . The schist was derived through the recrystallization of shale during the intrusion of the pegmatites, the graphite being derived from amorphous carbon in the shale. The intrusion of the pegmatites, and therefore the size and quantity .of the graphite flakes, seems to have a structural control.

Jan 1, 1948

By Hugh D. Pallister, Richard W. Smith

The Alabama flake-graphite industry has flourished only in times of war when importations of foreign graphite for crucible use have been greatly curtailed or cut off. World War I was a boom period and in 1918 some 30 plants produced 7,795,475 Ib. of flake graphite. The industry languished following the war and no graphite was produced from 1929 to 1939. The Federal Bureau of Mines began investigating the Alabama graphite deposits in 1940 and worked out modern recovery methods that were applied to production during part of World War 11. A prospecting program disclosed reserves of over 25 million tons of graphtic schists. In 1942 the War Production Board authorized the enlargement of the only plant then producing flake graphite and the construction of two new plants. Production of flake graphite from these three plants in 1943 is estimated at 8,100,000 lb. Increased imports from Madagascar late in 1943 shut down one of the new plants and curtailed production at the other. Alabama flake graphite has not yet been able to compete with Madagascar graphite for use in the manufacture of any but small graphite crucibles. The future of the industry must depend on meeting the higher carbon content demanded for other uses. Introduction The flake-graphite deposits of Alabama are confined to a narrow belt extending for about 60 miles southwest from the northeast corner of Clay County across Coosa County to the edge of the Coastal Plain in Chilton County (Fig. I). The continuity of the beds is broken by a 10-mile gap between Millerville in Clay County and Goodwater in Coosa County. The Clay County beds extend about 27 miles northwest of this gap, with a width of 3 to 4 miles near Millerville and of less than a mile at the northeast end. The Coosa-Chilton are? is about 33 miles long with a fairly consistent width of 2 to 3 miles. Geologically the graphite belt lies near the northeast boundary of the outcrop of metamorphic rocks of the Ashland series, a complex group of intensely folded and faulted beds of pre-Cambrian age composed mostly of quartz-mica schist, in which the mica is predominantly muscovite; garnet-mica schist, in which biotite is more common; and hornblende schist. Flake graphite is found in commercial quantities only in the quartz-mica schist. The best graphite, both in quantity and quality, is found in schist cut by numerous small pegmatite stringers along the planes of the schistosity. The pegmatites themselves contain little graphite, but the adjacent country rock is normally rich. . The schist was derived through the recrystallization of shale during the intrusion of the pegmatites, the graphite being derived from amorphous carbon in the shale. The intrusion of the pegmatites, and therefore the size and quantity .of the graphite flakes, seems to have a structural control.

Jan 1, 1948

By C. G. Goetzel

E. V. Crane.*—I want to ask Dr. Goetzel concerning the control of atmosphere in heating and pressing. Was the heating and pressing done in the die, or were the two kept separate there? C. G. Goetzel.—The setup used for this investigation implied heating the die to the temperature at which the work was to proceed, introducing a preformed compact into the hot die. The atmosphere was supplied through an annular chamber from which it passed through two holes into the die cavity. E. V. CRane.—The compact was not preheated? C. G. Goetzel.—The compact was not preheated. Tee Chairman.—In the course of recent studies on the effect of time of heating upon the tensile strength and hardness, I have observed that there is often a maximum in tensile strength and hardness reached before complete homogenization has been attained. The magnitude of each mechanical Property changes rapidly with time in the early stages of sintering, the more so as temperature increases. For these reasons it seems that the comparison of values obtained by heating for the same time at a series of temperatures may be deceptive. Not only may those heated at higher temperatures give higher tensile readings, but the reverse may be true if the maximum in the tensile strength versus time curve has been passed. A better basis for comparison would be that of equal degree of diffusion. C' " Goetzel.—Thank you, Professor Rhines, for this interesting contribution. I would like to add here that I have noticed a similar effect with straight copper. There is, of course, the possibility that this maximum in hardness and tensile strength may be caused by work-hardening.

Jan 1, 1945

By Alan M. Bateman

Before World War II we proudly considered that we were the nation of all the world most richly endowed in mineral resources. We knew it was no accident that those countries abundantly supplied with mineral resources became the great manufacturing nations, and the politically and militarily strong ones; and that our own great industrial cities sprang up where coal and iron met. We all reallized, especially we of the mining profession, that the energy of fuels and the solidity of metals spelled industrial growth and in turn industrial might and that other nations came to regard mineral self-sufficiency as one of the chief goalsof economic nationalism.

Jan 1, 1949

By E. H. Kelton, R. D. Grissinger

E. E. Schumacher.*—DO YOU control the humidity in your test room? What effect does the environment have on your results? E. H. Kelton.—We do not attempt to control the humidity. As a matter of fact, the humidity in the beam tests that were conducted in a constant-temperature room varied widely and, as far as we know, there is no effect. The tension tests were conducted largely in an oil bath. I suppose there would be an effect in highly corrosive atmospheres, sufficiently corrosive to notch the specimen; otherwise, I would say none. E. A. Anderson.*—The effect of the humidity on the corrosion of zinc does not become important until the relative humidity is 70 per cent. At that point the corrosion products are capable of absorbing moisture and the corrosion rate increases. Below that point corrosion is almost imperceptible. This does not take into account any effect due to stress. That may be important. E. E. Schumacher.—Recently 1 have become very conscious of the enormous effect that surface films can exert on the physical properties of certain alloys. Shortly, we are publishing an article in which it will be shown that the fatigue endurance of some lead alloys can be changed markedly by merely changing the type of film placed on their surfaces. Changes as great as tenfold were observed. These findings make me wonder whether in your creep test you might not obtain quite variable results, depending upon the type of liquid medium used to immerse your specimens. Did you use more than one type of oil and, if you did, what were your results? E. H. Kelton.—I think we have used no more than three different oils, and we could not see any difference in effect.

Jan 1, 1945

By R. S. Shoemaker

Mines are closed for two reasons; exhaustion of ore or insufficient price for the mineral. On the other hand, the reopening of an old mine can be the result of any one of three events; the discovery of more ore, a sudden rise in the price of the product or the use of a new low-cost method of mining or milling the ore. Examples of the latter would be the open-pitting of an orebody previously mined underground as recently happened at Tyrone, N.M., or the adoption of acid leaching of an old pit as has been done at Miami, Ariz. The unique native copper mines of the Keweenaw Peninsula of upper Michigan have not been so fortunate. These deposits, which were first worked by prehistoric Indians, have been mined continuously from the early 1840's to 1968 when the last mines of Calumet and Hecla were closed and the Ahmeek mill. still using eight Nordberg steam stamps, was shut down. There are two types of deposits from which native copper is obtained; amygdaloid, which is a lava flow, and conglomerate, a sedimentary deposit of sand, rock fragments and pebbles cemented together. "In the amygdaloid, the copper is disseminated, or distributed much like the raisins in a cake; but in the rich Calumet conglomerate, the copper is more like a malleable rope or thread cementing the pebbles together." (C. Harry Benedict. Red Metal: The Calumet and Hecla Story, (Ann Arbor, Michigan, 1952), p. 42.) These deposits produced almost all of the copper used by the North in the Civil War and were substantial contributors to the copper needs of the United States in both World Wars. Some were mined to depths of as much as 9500 ft along the dip of the vein structure and 7500 ft vertically. Few of the mines ever really became worked out, but became uneconomical because of depth, pinching of veins or grades which dropped to about 1%.

Jan 5, 1972

By Augustus Locke

WHY should I, a geologist, be coming before you to talk about finding ore? Certainly, the great discoveries of the past have not been made by geologists, but by men of very different tastes and training. If, in the year 1800, the course of ore discovery could have been foreseen, there would have been no reason to put it into the hands of geologists or other men of technical preparation. It was not geologists but explorers, Indian fighters, prospectors, manual laborers, and hardy financiers, who initiated the American mining industry. Then why this association of geological technique with ore finding? Why this feeling that the way to find ore is to apply to the problem what we call geo- logical principles? Well, to put it broadly, the old method has run out on us. It no longer works. Or, to put it another way, the cost of finding ore by the old method has mounted so high that one old district after another has become, practically speaking, dead, and various other old districts that are still going apparently at full strength are actually beginning to limp, and, with the cost of discovery mounting yearly, to fear, more than they will acknowledge, that the end is approaching.

Jan 1, 1926

By G. Thodos, W. F. Stevens

The point-source function introduced by Horner' us a solution to the general unsteady-state equation for the flow of fluids through porous media has been utilized to calculate pressure profiles for adjacent wells as a function of time. By trial and error, the time at which the pressure waves meet to cause interference can then be calculated. For this calculation, the time of interference is arbitrarily defined as that time when both pressure waves exhibit a pressure decrease of 25 psi ar the same point within the formation. To illustrate the method, an example involving two adjacent wells producing at different rates has been worked out and is presented in detail. INTRODUCTION The initiation of production of a new well is usually accompanied by pressure drawdown measurements in order to establish the extent and characteristics of the formation. The interpretation of such pressure drawdown data is based on mathematical developments involving a single well in an infinite reservoir. If more than one well is present in a reservoir, the possibility of interaction between wells exists. Therefore, care must be taken in interpreting the pressure drawdown data. It becomes important to be able to determine when this interaction, or interference, becomes significant. This paper presents a method for the prediction of the approximate time of interference between two such adjacent wells. The basic differential equation describing the pressure distribution existing during unsteady-state flow of a slightly compressible fluid has been solved by Hor-ner.' for a constant production rate from a circular homogeneous reservoir of infinite extent. The solution utilizes the point-source function to define the pressure at various points within the formation as a function of time. The resulting expression is: q = production rate, STB/D ,;= formation volume factor, dimension-less µ = fluid viscosity, cp k = formation permeability. md H = formation thickness, ft C - fluid compressibility, psi' F = formation porosity, dimensionless R = distance from centerline of well, ft T = production time, hours Ei(—u) = Ei-function of U Eq. 1 may be used to calculate the pressure profiles generated during production from a single well in an infinite reservoir.

By D. J. Coolidge, H. L. Sheakley

THIS paper does not deal with all sands used in the glass industry in Missouri; it covers only that used in the plate-glass factory at Crystal City. However, it is probably safe to say that other sands, pro- [ ] duced throughout the state for this purpose, are of identical nature. The glass sand used in Missouri is commonly called the St. Peter deposit, which is ascribed to the Ordovician Rock series in the form of sandstone. This St. Peter deposit, aside from a few small outliers, covers a large area of eastern Missouri. It forms, through a broad curve, the northeast margin of the typical Ozark region between Cape Girardeau on the southeast and Mineola, Montgomery County, on the northwest. The belt is extremely irregular, varying from one to ten miles in width; its length is 150 miles in a straight line. [ ] The outcrop near the entrance to the Crystal City mine appears in the form of a sandstone bluff approximately 30 ft. high, running along Plattin Creek (Fig. , I). Above the sand rock an overburden of Joachim limestone appears, which, thickens to nearly 300 ft. and forms the hill commonly called Buck Knob. Test holes, where drilled at various points and the drillers' log indicate that the St. Peter deposit ranges in thickness from 63 to 71 feet. PROPERTIES OT THE ST. PETER SAND From an analysis of the glass sands of the St. Peter formation in Missouri, the follow-

Jan 1, 1942

By L. Adler

Two basic cases involved in the design of an opening in bedded rock are: 1) where the beds deflect from each other so as to be separated; and 2) where the beds deflect onto their lower neighbor, loading the latter while reducing their own load. Analysis of case 1 is relatively simple, while the interference of the original deflection curves in case 2 complicates analysis of the latter. Figures and formulae are presented for determination of interference loading in this situation. The design of an opening in bedded rock involves two basic alternatives.1'2 In one case the beds deflect away from each other, so as to be separated from their neighbors; in the other case the beds deflect onto their lower neighbor, loading it, while reducing their own load. This is shown in Fig. 1. The first case lends itself to a simple analysis, since the upper and lower boundaries of each beam remain a free surface. In the latter case, however, due to the interference of original deflection curves, the analysis is more complex. Earlier investigators of this interference problem solved it by making the tacit assumption that this type of loading was uniformly distributed along the beam's length. While there is no intuitive justification for this assumption, its use does lead to an approximate solution. Still, a more exact solution does not require this apparently unrealistic restriction. To achieve initial simplicity, the analysis will at first be limited to a two-bedded sequence, as in Fig. 2. Since both beams have identical end conditions and spans, the original deflections of their center lines are members of the same family of curves, as shown in Fig. 3. Therefore, if interference occurs at one point along their center lines, it will occur at every point. For convenience, the midspan point is that usually examined. Deflection at midspan for a uniformly loaded beam regardless of end conditions is: where c is a constant depending on end conditions; w is the body load and equals yh, lb per ft; y is the specific weight of rock, lb per ft'; L is the span, ft; E is Young's Modulus, lb per ft2; I is moment of inertia (for a rectangular section), I = bh3/12 = h3/12, (ft4); b is the width of beam and equals one; and h is the thickness of beam, ft; or 3U > yB an Substituting the appropriate values into Eq. lb, interference between the two beds can be predicted. Should it occur, the additional loads along the lower boundary of the upper bed and the upper boundary of the lower bed must be determined. From the principle of action and reaction, these added loads are known to be equal and opposite, as indicated in Fig. 4. Since the final deflection curves for both beds are identical (Fig. 3), their successive derivatives of y with respect tox must also be identical. That is:

Jan 1, 1961

By George A. Laird

I. INTRODUCTION. THIS old and once famous district played, through its enormous production of silver and gold, an important part in the history of the State of San Luis Potosi. According to a pamphlet prepared under the direction of the Governor of the State, Sr. Don Blas Escontria, and presented to the visiting members of the Institute during the Mexican meeting of 1901, this district is situated 20 km. east of the city of San Luis Potosi, in a range of mountains of moderate height, extending 135 km. N. and S., and 16 km. E. and W.; and the mineralized area hitherto developed is about 600,000 sq. m. The history of the district,. as given by the record dated 1778, and formerly kept in the San Francisco convent, says that it was discovered in 1575 by Sr. Don Pedro Irarte, and adds that the city of San Luis Rey de Francisco del Potosi received its name (in allusion to the famous Potosi mines in Bolivia) by reason of the remarkable productiveness of its gold- and silver-mines in the first period of their exploration, during which they paid to the Crown, as " quintos " (the fifth part of the product), $97,000,000, as appears from the accounts of the royal treasury. The amount of the quientos paid during the " bonanza period " of 80 years was $72,000,000. The larger sum first mentioned probably represents a longer series of years. But either will suffice to indicate the great wealth of the mines. In 1663, the decadence of the industry began with the caving¬ in of several mines, concerning which the record of 1778, al¬ready cited, says, in substance, that on Good Friday one of the owners in the enterprise, in view of the unfavorable prospect of a lawsuit in which he was engaged, set fire to the timbers supporting the underground galleries and workings of the San

Jan 1, 1905