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By George E. Roberts

The maintenance of the common gold standard is the most important cooperative undertaking in the world. The war broke up this relationship and brought about a state of great disorder in the currencies and exchanges. After the war the countries all began to grope their way back to the gold standard as the best means of establishing trade and financial relations with each other. With this movement began a general decline in commodity prices. The question has been raised whether the world's return to the gold standard was not forcing prices back to the prewar level. Also, the question is raised whether the world has not outgrown the supply of gold as the basis of credit. Because Europe readjusted its monetary units to conform to the higher level of prices there is no pressure on prices on this account. Furthermore, a large amount of gold formerly in hand-to-hand circulation passed out of circulation and has been added to the central bank reserves. The gold reserves of 36 countries increased approximately 100 per cent from the outbreak of the war to June 30,1930. The increase is much larger than the average increase of prices in any of the important countries, at any time since 192.5. As gold in the central banks of issue is far more effective for all business purposes than gold in circulation, the gold scarcity argument has little basis as applied to this time. The abnormal distribution due to the war was to the disadvantage of business everywhere. Credit was scarcer and dearer in some countries. The inflation in this country might have been greater had the production of gold been greater. The argument supporting the theory of a scarcity of gold assumes as fundamental that general price changes must be accounted for by changes in the price equation on the side of money. This is disproved in every period of business depression. A downward price movement is characteristic of every period of business recession. Important discoveries of gold must be made even to maintain present gold production, in the face of which the world's business is bound to continue increasing. It cannot be doubted that some way will be found

Jan 1, 1931

By Earl S. Greiner, Eric R. Jette

The constitution of the iron-rich iron-nickel-silicon alloys at 600ºC. has been determined by X-ray crystal structure methods. If the results are represented isothermally by a conventional equilateral triangular plot, the single-phase solid solution (body-centered cubic structure) of the iron-rich alloys at 600°C. is bounded by four two-phase areas. Three three-phase areas separate the respective two-phase areas. Three of the phases in the polyphase areas have the same structures as the corresponding phases in the binary iron-nickel or iron-silicon alloys. There are two phases, however, that have not been reported previously and whose structures have been tentatively identified in the present investigation. The solid solubility limit of the iron-rich solid solution at 600°C. was determined by comparing the lattice constants of this body-centered cubic phase in the single and polyphase areas. It has been shown that the lattice constants of ternary alloys may be represented by surfaces whose distances above the ternary plot (representing atomic composition) are proportional to the lattice constants of the respective alloys. Then the intersections of the surface for the single-phase alloys with those for the corresponding phase in the polyphase alloys, at the respective temperatures, are the solid solubility limits of the single-phase alloys at these temperatures. The data of the present investigation were evaluated by this method, although by a system of orthographic projection it was possible to represent the three-dimensional model in two-dimensional diagrams. This investigation has shown that the solid solubility of nickel in the body-centered cubic phase of the iron-rich iron-nickel-silicon alloys at 600°C. changes from 3.7 weight per cent (Owen and Sulley) in the binary iron-nickel alloys to 5.0 per cent in the ternary alloys containing 4.8 per cent silicon. Further additions of silicon increase the solid solubility limit of nickel to 16.0 per cent at 12.6 per cent silicon. From this point the limit decreases to 9.5 per cent nickel at 15.5 per cent silicon and is, of course, zero at 15.3 per cent silicon in the binary iron-silicon alloys.

Jan 1, 1943

By R. H. Richards

The spitzlutte, as described by Rittinger, is an instrument by which saud is sorted in a continual upward-flowing stream of water. Its usual firm is that of a pointed box, placed with the point downward, the box receiving. its feed of sand and water on one side and discharging its tailings on the other. The sorted product or concentration is discharged at the bottom, at the apex of the box, through which it falls against an upward current of water, which current serves to effect the sorting and separation. To make this exposure to the quicksand condition still more effective, an inverted dam is placed across the spitzlutte, which forces the sand in its passage from the feed side to the discharge to pass clown into the more active portion of the upward-flowing current of water. In the form adopted for small tests in the mining laboratory of the Massachusetts Institute of Technology (see accompaaying sketch) the feed is'throogh a central funnel instead of being at the side, and the apex of this funnel, extending down nearly to the apex of the cone, talks the place of the inverted dam in the large spitzlutte. To keep the experiment perfectly under control a bulb or bottle is attached by a rubber connecting-tube to receive the concentrations, and between this bottle and the apex of the spitzlutte is placed a glass tube of conical form, with a side tube for' the admission of water. By regulating the admission of water through this tube the concentration may be allowed to go down into the bulb as fast or as slowly as the richness of the ore seem.; to demand. This spitzlutte may be used on products that have been previously sized to take out the heavy mineral. As an example of this a test was made upon a sample of ore where the galena, blende, and quartz were much mixed up, but separated fairly when crushed. The sample of ore was from Newburyport, and assayed 16.61) per cent. lead.. After sizing through a series of sieves the ore yielded conceutrations and tailings to the spitzlutte as follows :

Jan 1, 1881

IN welcoming the attending members of the Ameri-can Zinc Institute's Ninth Annual Meeting to St. Louis on April 18, the president of the Chamber of Commerce stressed the notable progress that had been made during nine years, marked by many price de-pressions and internal dissensions, while controversies between miners and smeltermen threatened to wreck the organization, prices dropped, and consumption grew languid for want of organized publicity and research. The reports and recommendations of Percy B. Butler, chairman of the Adjustment Committee, and F. C. Wallower, chairman of the Galvanizing Committee, might well be adopted as the institute's objectives. In reply to the speeches of welcome to St. Louis, Arthur Thacher reminded the delegates that the cor-ner stone of progress in the mineral industries was laid by the formation of the American Institute of Mining Engineers in Wilkes-Barre, Pa., in 1871, and the dedication of that organization to the exchange of ideas and methods of the winning of metals and non-metals from their crude state. The activities of the American Zinc Institute constitute, he said, a valuable phase of that work. Mr. Thacher forecast the treat-ment of 1 per cent zinc ore. After the reading of the report of the board of directors, in which Scott Turner and Louis Boschern were named as honorary members of the institute, a survey of world zinc conditions by A. J. M. Sharpe of London was presented. He held pres-ent conditions in China responsible for much of the present depression in zinc. World stocks on, April 1, 1927, were estimated as 52,900 metric tons. Adolph Boldt's paper on "Solidarity in Industry" was followed by a survey of the Tri-State district by Otto Ruhl, who emphasized the importance to the dis-trict of the organization of the Tri-State section of the A.I.M.E., which already has 135 members and asso¬ciates. He also mentioned .that flotation in the Tri¬State field is adding 1500 tons of concentrate to the weekly production. "Mining Economics" was the subject of Julian D. Conover, secretary of the Tri-State Zinc and Lead Ore Producers Association. He gave a detailed report on the costs of mining and milling in the district.

Jan 5, 1927

By A. B. Young

The difficulties encountered in the preparation of the lead smelter charge for the blast furnace and in the roasting and sintering of the ores, and the expert means taken for the preparation of these materials since the introduction of flotation concentrates into the lead smelter charge, have been described by W. H. Eardleyl and R. A. Wagstaff.² Function of Roasters and Blast Furnaces The lead smelter has first its roasters and its sintering devices, of which the primary object is the removal of sulfur from the ore or from the charge. The blast furnace follows; its function being the elimination of the gangue material left in the charge—the elimination of the insoluble, the iron, the zinc and the lime from the metallic lead. The secondary object is the separation of copper from the lead. A lead blast furnace is a sensitive apparatus. The materials composing the charge must be marshalled in certain proportions before they will make a fluid slag which will separate from the metallic lead. The silica, iron, lime and zinc must be put together in proportions that usually do not mist naturally in the ores, therefore fluxes are necessary. Function of the Flotation Cell The flotation cell—-speaking from the standpoint of a lead concentrate—has taken over part of the work hitherto performed entirely by either gravity concentration or the lead blast furnace. It has eliminated gangue from the concentrate and separated waste products from the lead. In so far as it has done that, it has usurped some of the function of the lead blast furnace; and it is much cheaper to run a flotation cell than a lead blast furnace. The effect in Utah, and it will be similar to effects in other districts. has been to remove a great deal of the gangue by means of flotation, whereas in the old clays it was eliminated by means of sme1ting. In this district, as in others, the insoluble content of the ores has been greatly out of proportion to the iron and lime content to make a proper slag

Jan 1, 1928

F. JOHNSON,* Birmingham, England (written discussion t).--. Mr. Skowronski's first melting experiments tend to show that ingots with a "level set" may be obtained without oxygen. Now it is characteristic of all metals which occupy a smaller volume when solid than they do when molten to "pipe." In vertical-cast ingots, this pipe resembles a horn-shaped cavity, with the wide mouth uppermost. In horizontal-cast ingots, the pipe is a longitudinal furrow along the center-line of the ingot surface. If copper be successfully deoxidized and degasified, this furrow will inevitably be produced. In the author's oxygen-free ingots, it is. clear that gases were occluded and these gases effectively opposed the formation of a pipe or furrow by shrinkage (fluid contraction). It is riot a special property of any particular gas which produces this effect. Hence it is not surprising that the author has succeeded in producing level and overpoled ingots through the agency of sulphur. dioxide gas. That he has counteracted the overpoling influence of sulphur by means of oxygen is somewhat difficult to explain, since the well known reaction between cuprous sulphide and cuprous oxide should result in the production of sulphur dioxide gas. Why the presence of excess cuprous oxide should neutralize the overpoling influence of this gas without eliminating sulphur is not at all clear. It is to be regretted that the oxygen was not determined in the bars given in Tables 3 and 4. It is by no means established that sulphur is responsible for the over, poling of ingots given in Table 4, since carbon was used for overpoling. If, however, the same kind of poling treatment was given as that applied in the case of ingots in Table 1, the responsibility of sulphur assumes more definite shape. The author rightly points out that Mr. Johnson's theory of the equilibrium between gases and cuprous oxide does not explain why a simple addition of cuprous oxide does not correct an overpoled charge. Such a charge must be re-worked to "set" copper. This re-working (rabbling) undoubtedly forcibly removes the excess gases, which are not removable by cuprous oxide.

Jan 11, 1918

CHARLES F. WILLIS,* Bisbee, Ariz.-(written discussion?).-The consensus of the discussion of the paper of Dr. Lanza indicates that the physical examination, while it is probably a good thing, is fought by the workingman, and that, because of this fact, it has been proved unsuccessful. The physical examination standing alone is worth but little, and could easily be made a subject both of ridicule and dissension unless the company having such examination shows its own good faith in promoting a thoroughly better health program. It is easily seen why a workman would resent his employer expecting him to be physically fit, if at the same time the employer provides un-healthful, unsanitary, working conditions, or if the town in which the employees are expected to live is dirty and unkempt. One mocks the other. The employer cannot say, "You must remain healthy so that I can get by with unhealthy conditions." But if working- conditions are as good as can be obtained to keep men well, the employer can ask his men to be in a healthy condition. A State examination and standard would have many difficulties, owing to the fact that a man would pass or would not pass the standard set, thus eliminating the discretion on the part of the employer in placing men whose physical condition might well permit working in one place and not another. Any physical examination that is run for the purpose of eliminating the physically unfit is unjust, both to the worker and to the nation as a whole; a State examination would make a distinct dividing line, whereas examination by the employer is conducted with a vision of the positions available. The workman's opposition to the physical examination comes from the fact that he has been taught to believe that it is an interference in his personal affairs, that he can be clean or dirty as he chooses, that he can he healthy or unhealthy, and that it is nobody's business but his own. The war has taught us, however, that the individual is no longer the unit and that all such propositions must be based on the greatest good for the greatest number.

Jan 6, 1919

Francis Drake, Bulawayo, Rhodesia, So. Africa (communication to the Secretary *):—I should like to place on record some data in addition to those given by Mr. Canby in his paper. I regret that my notes have been destroyed so that I can give no accurate measurements of the water jacket that I am about to describe. This furnace mas erected in Cerro Gordo, Inyo county, Cal., early in 1875, and I think it quite possible that it was the first applied in lead smelting. It was made of plate iron and elliptic in shape, the inner dimensions being about 54 by 42 in. by 48 in. high. The distance between the inner and outer plates was about 6 in. Tuyere holes, one at the back and two on each side, about 12 in. in diameter, were made in this, and in these were placed cast-iron water tuyeres about 16 in. long, the diameter of the blast orifice at the point being about 3 in. The height from tuyeres to feed door was about 9 ft., but the top of the charge was kept about 5 ft. above the tuyeres. There was a space of about 12 in. between the jacket and the top brick-work. This brick-work was supported by a cast-iron plate resting on four cast-iron columns. At the beginning, the jacket was lined with air-dried radial bricks, made of crushed quartz and fire-clay, as it was thought that the jacket would not stand the heat on its bare plates. After a short time the practice was altered and no lining mas put in. The jacket was closed at the top and had a steam drum connected by two pipes at the back. This steam drum was connected to the boiler in which the steam was made for driving the Baker blower, the rock breaker and the pumps. The bottom of the jacket mas also connected to the boiler. The jacket was run under boiler pressure (80 Ib.) for some time, but eventually cracks developed in the inner plate between the tuyere holes,

Jan 1, 1913

By C. R. Hocott

The distribution and movement of fluids in oil reservoirs are influenced to a great extent by capillary forces, which depend upon the size and shape of the pores in the reservoir rock, the surface characteristics of the rock, and the interfacial tension between the fluid phases. This paper presents the results of an investigation of the interfacial tension between salt water and crude oil containing dissolved gas under reservoir conditions. Apparatus and Procedure In the preliminary phases of this investigation, it was found that a scum formed at the oil-water interface, which made measurement of interfacial tension by either the ring or capillary rise methods unreliable. Accordingly, the drop-weight method, in which a fresh interface is continuously formed, was selected. In this method, a tip through which drops of one fluid can be expelled is immersed in a second fluid. At the instant that the drop becomes large enough to fall, the gravitational force tending to pull away the drop exactly balances the interfacial force tending to hold it. From the size of the drop, the dimensions of the tip, and the density of the two fluid phases, the interfacial tension may be calculated. The apparatus consists of a circulating pump for bringing the oil to equilibrium with gas at the desired pressure, a displacement pump for forming the drops, an interfacial tension cell in which the drops are formed, and a density cell to determine the density of the oil. The density of the water is determined separately in another apparatus. A flow diagram of the assembled equipment is shown in Fig. 1. The interfacial tension cell contains a stainless-steel dropping tip suspended from the top and extending below the surface of the oil. The tip is a cylindrical rod with a small hole in the center through which the water was forced to form the drop on the lower face. The walls of the tip were highly polished, to prevent the water on the tip from creeping up the side and increasing the effective diameter. The face of the tip, how-

Jan 1, 1939

By V. R. Garfias, R. V. Whetsel

As pointed out in previous studies, estimates of petroleum reserves if they are to be of value must not only presuppose a clear understanding of what is actually meant by reserves but must be subject to constant revision to conform with changes in their component factors. When such estimates are analyzed it must be clear that it is virtually impossible to obtain comparable figures reflecting the same degree of accuracy, to represent the reserves not only in various countries, but at times even of different fields in the same country. Estimates of reserves in the United States, subject to frequent independent checks, are obviously more reliable than those furnished, for instance, by the Soviet Government, as the latter must be accepted at their face value and are open to the suspicion of being made to conform with predetermined programs of propaganda. Any tabulation of the reserves of all producing countries, therefore, gives a total that is misleading, as the component items arc not arrived at on the same basis and therefore are not homogeneous in a true sense. Only a fraction of the petroleum stored underground, usually associated with natural gas, is or can be brought to the surface, and although practically all the natural gas underground can be rccovered, in actual practice in some fields a large part of the gas that reaches the mouth of the well is wasted. It is thus estimated that in the United States only some 25 to 35 per cent of the petroleum underground in proven fields is actually economically recovered. Estimates of reserves, therefore, should make clear the distinction between the known amount of oil underground in producing fields and the portion that actually can be brought to the surface. It cannot be overemphasized that as a result of the operation of the "Law of Capture," which controls subsoil ownership in the United States on comparatively small landholdings that seldom if ever cover the entire producing area, the oil fields are not as economically exploited as some forrign fields, and that as a result (were it not for the easy accessibility of the domestic market, the largest in the world) some American production would now be unprofitable in open competition with foreign oils.

Jan 1, 1939

THOMAS L. WATSON,* Charlottesville, Va. (written discussion ? ).¬Sphalerite, as is well known, occurs not only as a common constituent of many types of ore deposits formed under widely varying geologic conditions, but its sulphide mineral associates comprise a goodly number of species. In the investigation by Mr. Teas, data were obtained from a mineralographic study of about 200 ore specimens from 43 different localities grouped according to their genesis as follows: (1) Contact-metamorphic deposits, (2) deep-vein zone deposits, (3) intermediate-vein zone deposits, (4) shallow-vein zone deposits, (5) meteoric water deposits. .The object of the study was to determine the relations of sphalerite to the associated sulphide minerals and their possible genetic significance. As a result of the investigation, Mr. Teas has deduced several important conclusions. Probably the one of largest interest and value was that sphalerite formed from magmatic waters, including contact-metamorphic, deposits, could be distinguished, for the cases investigated at least, from sphalerite formed from meteoric waters, by development in the former of minute triangular or rectangular dots or stringers of chalcopyrite. Although chalcopyrite inclusions in sphalerite had been noted by previous observers, the probable significance of their apparent general occurrence in sphalerite of certain types of ore deposits and their absence from others was unknown. The large number of ore specimens studied from more than 40 different localities in the United States and foreign countries, representing the principal genetic types of sphalerite-bearing deposits, gives considerable weight to the conclusions reached by the author. Should the conclusion drawn by Mr. Teas become generally applicable, a laboratory criterion of much value will have been established for distinguishing between sphalerite formed from juvenile and that from meteoric waters. The principle seems applicable not only to sulphide deposits in which sphalerite is the principal constituent, but to those in which it occurs as a very subordinate one, as shown by the study of ore specimens from one of the principal pyrite mines in Virginia. It may be possible also that the principle will have important application in differentiating primary from secondary sphalerite occurring in the same deposit formed from magmatic waters, although there have-been comparatively few well-

Jan 4, 1918

By Huntington Adams

The arrangement of a flow of cyanide-pulp through Pachuca tanks in agitation, so as to permit a continuous process, instead of alternate filling, agitation, and emptying, has been proposed by various writers within the last two years, and more particularly by A. T. Grothe, agent for the Brown patents on Pachuca tanks in Mexico. It was first put into practice, I believe, by M. H. Kuryla at the Esperanza mine in El Oro, Mexico. The starting of agitation in Pachuca tanks after filling may offer no serious difficulties with ores which do not settle rapidly in such tall tanks; and the adaptation of the tanks to continuous agitation under such conditions may give simply a somewhat more convenient method of treatment and greater agitation-capacity for a given number of tanks, because of the saving of time lost in filling and discharging. But in the treatment of pulp which tends to settle rapidly, as in the cyaniding of concentrates or of the whole pulp of ores containing heavy sulphides, the packing of the slime at the bottom may cause much trouble. The use of the radial air-pipe attachments near the top of the cone and of the air-valve outside of the air-lift tube at the bottom may obviate the difficulty to some extent; but the action of the radial air-pipes on the cone-sides is that of a sand-blast, and their continuous use cuts through the tanks. Moreover, even when these pipes are used, some pulps will pack tightly below them in the cones. Under such conditions the use of Pachuca tanks with intermittent filling and discharging becomes a troublesome process. Time is lost in starting agitation; large quantities of compressed air are wasted; pulp is blown over the tank-tops; and not infrequently it may be necessary to dig out the bottoms of tanks by hand. This trouble is the only important one occurring in the use of Pachuca tanks; and, since it is caused by intermittent filling, the arrangement of a continuous flow of pulp from tank to tank,

Jan 1, 1912

By S. R. Elliott

THE principles of the caving system, as they apply to mining of soft iron-ore deposits, are well known, as this method has been in use for many years. It is, however, necessary to give a general description of it before describing the Athens method. The shaft and surface equipment should be placed at a sufficient distance from the orebody, so that the caving and pulling of the surface will not disturb the operations of the mine. Levels are started at the proper intervals, and when raises are completed, slicing commences at the top of the orebody and progresses downward. The necessary precautions are taken to avoid the occurrence of large open rooms and it is customary to break sufficient capping to form a mat to prevent heavy falls of ground from crushing through to the lower sublevels and endangering the lives of the workmen. Slicing is continued, and when sufficient width and length are undercut, the capping commences to cave, and in time a settlement occurs at the surface. As soon as this caving commences, the pressure on the timber naturally increases; after it extends to the surface, the amount of pressure has a certain relation to the depth. In other words, the pressure increases with the depth, but not in direct proportion. At great depths, such as that found at the Athens, 2500 ft. (760 m.), the pressure might be so excessive that the cost of keeping working places open would be prohibitive. The actual caving of the surface in a deep mine, with a great thickness of capping, is slow and often takes years to accomplish. After sufficient width and depth -have been undercut, the capping starts to break away, but through arching large masses of rock-.fill the opening, support the capping, and retard the continuation of caving. Caving to the surface is, therefore, retarded until either a sufficient thickness of the orebody is removed, or the width and length of the undercut part have been greatly increased. I wish to emphasize this fact of slow caving, for it is on, this principle that the success of the Athens system. largely depends.

Jan 8, 1920

By M. Gensamer

IT has been suggested by a number of people that it would be worth while for some one to attempt to summarize or condense the proceedings of this symposium. This task has fallen to me as organizer and co-chairman. Its difficulty will be appreciated by anyone who attempts to read the whole proceedings. It is therefore with trepidation that I offer the following digest. In recent years there has been a renewal of interest in America on this subject of the cohesive strength of materials, and a growing appreciation of the need for a better theory of cohesion failure. The theories of elastic action and plastic action are well developed, particularly the former. The theory of plastic action is still in the course of development, but it is well along. Plastic action is terminated by cohesion failure and what is needed is a theory that will tell us when to expect the cohesion failure. In the past it has generally been assumed that cohesion failure will occur when a critical value of the maximum tensile stress has been reached. Many experiments have shown that this is not strictly true, and this symposium concerns itself with the failures of this simple hypothesis, and with the efforts that have been made to devise a more satisfactory theory. The most active contributor in recent years to knowledge in this field is Dr. McAdam, and he was asked to open the symposium with a summary or condensation of his papers and views. Undoubtedly it is presumptuous to attempt a still greater condensation, but perhaps it will be useful, because even his contribution to this symposium contains no summary, no concise statement of just what his contribution has bees. Dr. McAdam makes two main points. The first is that the cohesive strength is not a single valued quantity, but that it is a function of all three principal stresses and hence must be represented diagrammatically by a surface in a three-dimensional figure. Dr. McAdam has attempted so to delineate the cohesion limit, basing his

Jan 1, 1944

By C. K. Leith

MANGANESE is one of the minerals which is principally consumed in countries other than those of origin. Nearly 85 per cent of the pro-duction is used by the United States, England, Germany and France, and roughly a third of the total is used by the United States alone. On the other hand, over 85 per cent of the world production comes from Brazil, Russia, India, the Gold Coast of Africa, and the Sinai Peninsula. It follows from this fact that practically all manganese moves across international boundaries in raw or alloy form, and much the larger part of this movement is for considerable distances and is ocean borne. There is no indication that any one of the principal consuming countries can develop even approximately adequate supplies of its own. Under abnormal war conditions, with high prices and changes in metal-lurgical methods, only 35 per cent of the needs of the United States was met from local sources, and under our recent tariff only 11 per cent. There are thousands of manganese deposits scattered about the world, but only a very few which can figure largely in supplying requirements on a modern scale. The known reserves, together with highly probable extensions and explora-tions now under way, indicate no shortage from a world standpoint for many decades to come. The production and marketing of manganese is going steadily into fewer and stronger hands. The steel in-dustry uses over 90 per cent of all the manganese mined, and is acquiring control of a considerable part of the production in all of the principal fields-the Germans in Nikopol, the English in India and Gold Coast, the Americans in Georgia, India, Gold Coast and Brazil. Some of the controlling companies are of international scope. Concentration of commercial control is a notable tendency. A natural consequence is the growing un-easiness of smaller consumers the world over about their ultimate supplies and desire to know more definitely how and where manganese supplies will be controlled in the future. The sources of supply are few enough to warrant the belief that more or less monopolistic ele-ments of control are not impossible.

Jan 5, 1927

By W. J. Hillenbrand

The soda-ash method for eliminating arsenic from a molten copper bath has been described previously in some detail.' Briefly, the process consists in blowing powdered sodium carbonate under the surface of the partially oxidized melt and in removing the slag formed, which will contain a certain proportion of the arsenic formerly in the bath. Sodium carbonate melts readily at the temperature of molten copper, and when molten it dissolves arsenic oxide rather rapidly. In the process, sodium arsenate is formed which is removed along with the excess of molten soda ash. In order that arsenic may be eliminated in this way, it must first be oxidized to the pentavalent condition. This, however, is easily accomplished by blowing air into the molten copper until a fair excess of cuprous oxide is present. The manner in which soda ash is introduced into the furnace has a considerable effect upon the efficiency of the process. In the earliest attempts at arsenic removal, soda ash—often in combination with slaked lime, for sodium carbonate is not the only solvent that will remove arsenic—was thrown upon the surface of the bath, was allowed to melt, and was removed after it had dissolved a sufficient amount of arsenic. At present powdered soda ash is generally blown in under the surface of the melt with the aid of compressed air. Melting immediately as it comes into contact with the molten copper, it can react with considerably more of the bath than by the former method, and thus can remove arsenic more rapidly and more completely. Since the resulting slag is removed at once, its very destructive effect upon the furnace refractories is minimized. The effectiveness of the soda-ash method may be gathered from the results of the following test. A 900-lb. charge of copper was melted in a small, oil-fired reverberatory furnace, and sufficient metallic arsenic was added to the bath to bring the concentration of that element to about 0.5 per cent. Air was blown into the melt until its oxygen content was just under 1 per cent by weight. The bath was then sampled and soda ash was blown in under the surface in 5-lb. batches. After each addition

Jan 1, 1934

W. C. MATTESON (communication to the Secretary*).-The criticism and question raised by Arthur Knapp regarding the standardization of nomenclature is most important. Faulty rock classification-is generally the result of carelessness or ignorance on the part of the driller. Two remedies might be suggested. In a field where several large companies are operating on an extensive scale, a geologist from each concern might be assigned to superintend the gathering of well-log data and the classification of samples. The geologists from the several operating companies might then combine their data, which would doubtless give valuable information to all interested parties. At present, coordination is not a big factor, unfortunately, but the time will come when conservation will demand such systematic coordination on the part of competing companies. The second remedy lies in instructing and educating the driller to a thorough understanding of the importance of an accurate log and correct classification of the various formations. The writer does not agree with the statement that "90 per cent. of the logs as taken today are absolutely worthless to any one but the one who has taken the log." While mistakes in nomenclature often occur, the driller is generally able to classify the important water-, oil-, and gas-bearing formations with a fair degree of accuracy. Such information is often sufficient to permit accurate correlation and also constitutes valuable data for projection purposes. It must be borne in mind that to attempt to use well-log data in a strict scientific sense of accuracy is impracticable and impossible. A broad interpretation and a comprehensive knowledge of the practical limits of such' information are essential in applying it successfully. Even experienced geologists do not always agree on rock classification. The question as to what constitutes correct nomenclature should receive the earnest and immediate attention of geologists, operators, and producers. Although standard textbooks on geology give correct definitions and descriptions of the general rock species, such textbooks fail to develop the subject in sufficient detail for the work under consideration. A committee composed of appointed members from the American Institute of Mining Engineers, the Geological Society of America, and the

Jan 6, 1917

By E. L. Estabrook, H. H. Hill

This report summarizes the information that was obtained by the Committee on Unit Operation in Eastern United States and in the foreign countries. Letters and questionnaires were sent to all of the Eastern members of the Petroleum Division of the American Institute of Mining and Metallurgical Engineers and to those who are living outside of the United States, asking them to advise the Committee of any unit operations that are in effect in the various countries of the world and to furnish the names of men to whom inquiries should be directed for detailed information on the different projects. The response to the Committee's request is worthy of note. Practically all of the members who had knowledge of foreign operations replied to the questionnaire and not only furnished information that was of value to the Committee, but they evidenced a real interest in the subject of unit operations and assured the Committee of their willingness to assist in every way possible in order to make the study a success. The Committee wishes, at this time, to express its appreciation of the excellent cooperation that was received from the members of the A. I. M. E. to whom questionnaires were sent. Unfortunately, the limited time that has been given to this survey did not permit the collection of detailed data on the different unit operations that are now in effect. It required several weeks to get back replies from the members located in some of the foreign countries and as a result the men who were asked to furnish information on the various projects have not had sufficient time to submit the detailed data that were requested. The Committee has been assured, however, that information relating to a number of unit operations will be furnished in the near future. Part of the delay has been due to the fact that the purpose of the study was not understood and because the terms "unit" and "near-unit" operations were not clearly defined. In the foreign countries, practically all of the operations in noncompetitive fields are on concessions or leases that have been granted to a single company and for that reason

Jan 1, 1930

By H. A. Wentworth

THE Huff electrostatic plant of the United States Smelting Company operated in conjunction with its wet concentrator at Midvale, Utah, was the second plant of substantial size installed using the Huff process, and the first plant to be put in operation on the so-called Western complex ores. In spite of the machinery being of early design and consequently embracing many of the mechanical weaknesses incident to a pioneer plant the mill has operated steadily and uniformly since the summer of 1909, about five years now, without any material change other than some re-arrangement of the machinery for better handling of the sizes. The ore, at present coming almost entirely. from the company's mines in Bingham, is of practically the same composition as that upon which the plant was first put in operation. The crude ore, consisting of the sulphides of copper, lead, zinc, and iron, and containing small amounts of gold and silver, is brought by train and delivered to the hoppers of the wet concentrator, where by jig and table treatment, there are produced a shipping lead concentrate, a tailing and a middling product, the latter being conveyed in push cars to the adjoining electrostatic mill. The crude ore delivered to the wet concentrator contains from 6 to 9.5 per cent. zinc. At times the plant is used also for the treatment of custom ores from the Bingham district and elsewhere, and at such times the results of the plant vary according to the material in use, but as by far the larger portion of the product is that from the company's own mines, the results given below are fairly indicative of the general work obtained. The accompanying diagram illustrates graphically the flow of the ore through the electrostatic mill. The middling coming from the wet mill containing from 15 to 18 per cent. moisture is hoisted while on the cars by an elevator, and delivered from the top of the elevator to a hopper over the drier. The drier first installed was of too low capacity to take care of the moisture present in the tonnage to which the mill was later

Jan 8, 1914

By W. D. Bennett

AN interesting effect has been observed in the vacuum etching of titanium in the high temperature ß phase. Using a high vacuum annealing furnace, operating at less than 2x10-6 mm with a tubular titanium liner, it has been found possible to etch polished metallographic specimens at different temperatures between room temperature and 1000°C without contamination or increase in hardness.' Heat etching of titanium has been reported by other workers,' but the following example is of interest as an experiment under high vacuum in the absence of any contamination. Two polished specimens of iodide-processed titanium are placed at different positions along the axis of the furnace corresponding to temperatures of 900" and 800°C above and below the a-ß transus. The specimens are then raised to these temperatures and annealed simultaneously for 3 hr under the same high vacuum conditions. After cooling and withdrawing the specimens, their surfaces are photographed without further treatment. Figs. 1 and 2 show the results for the 800" and 900°C specimens, respectively. Fig. 1, corresponding to a vacuum etch in the a region, shows a typical equiaxed structure with what appears to be a slight shift of grain boundaries. Fig. 2, corresponding to a vacuum etch in the ß region, shows an equiaxed type of structure with the growth of striations in certain grains. The striations are only superficial, as a light polish and chemical etch restores the clean equiaxed structure. The vacuum etch, occurring as it does above the a-ß transus, records the state of the metal in the ß phase by means of the surface relief produced by the selective evaporation of metal from different grains; the metal itself reverts to the equiaxed a on cooling. The nature of the ß etch" (Fig. 2) suggests that, in transforming from the close-packed-hexagonal a to the body-centered-cubic ß lenticular-shaped laminae are formed parallel to common planes of the two structures. This would explain why some grains appear to be unaffected by the etch. The technique has interesting possibilities in the investigation of the mechanics of high temperature transformation. Acknowledgment This note is published by permission of the Deputy Minister, Dept. of Mines and Technical Surveys, Ottawa, Ont., Canada.

Jan 1, 1956