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By Charles T. Baroch, Charles J. Baroch

In 20 years of commercial development, nuclear reactors have demonstrated that they are a safe, dependable, and economical source of power. Operating experience with commercial power reactors has firmly established nuclear power as a practicable source of energy. For both boiling-water (BWR) and pressurized-water (PWR) reactors, performances to date have generally met design predictions. Furthermore, it has become possible to analyze and understand the nuclear, chemical, and physical behavior of this class of reactors. The United Kingdom has had similar success with gas-cooled reactors. The Experimental Boiling Water Reactor (EBWR), the first United States experimental power reactor, began operation in 1956. It proved to be capable of supplying 4500 kw (kilowatts) of power. This reactor was followed in 1957 by the Pressurized Water Reactor at Shippingport, Pa. It was the nation's first full-scale central-station nuclear power plant and the first in the world designed exclusively for the production of civilian electric power. The Shippingport reactor was originally designed to produce 60 megawatts (MW) of electricity, and it was increased to 100 MW in 1964. In 12 years of operation, this reactor generated over 4.5-million MW-hr of electricity in spite of many shutdowns for experimental alterations. By 1969, a total of 15 central-station nuclear power reactors were operable in the United States with an aggregate electrical capacity of over 4200 MW. Early in 1964, Jersey Central Power & Light Co. announced plans for constructing a 515-MW nuclear plant at Oyster Creek, N.J., to be built without government financial assistance. The company stated that a nuclear plant had been selected competitively with fossil fuel. Their economic analysis stated that the plant would generate electricity at less than 4 mills per kw-hr, competitive with coal at 200 per million Btu (British thermal units). Coal cost in 1964 for that region averaged 26.00 per million Btu. The Jersey Central report created wide interest in public-utility circles; nevertheless, no other nuclear plants were announced in 1964. However, in 1965, six nuclear plants were announced by utilities, followed by 26 in 1966, 29 in 1967, and 10 in 1968. By Sept. 30, 1969, 97 reactors were operable, being built, or planned. The cost of these, all committed by electric utilities, was estimated at about $12 billion. When constructed, they will have an electrical capacity of 72,000 MW. The unprecedented surge in power reactors that started in 1965 tapered in 1968, and only seven reactors were announced in

Jan 1, 1976

By Jean A. Andre

In 1969 "Société des Mines et Fonderies de Zinc de la Vieille-Montagne" produced 221,000 tons zinc ingots and 22,000 tons zinc dust, thus rating highest on the world's zinc producer list. The Company's plant at Balen, Belgium, with an output of 135,000 tons electrolytic zinc is the most important one of this group; it is an integrated metallurgical zinc and lead unit with recovery of most by-products. The present paper describes the zinc production facilities. The roasting section includes four fluid bed roasters (total concentrates charged: 740 tpd) and two sulfuric acid having a corresponding capacity. Calcine is leached in a fully automated plant by a two-step continuous process. Leaching residues, mixed with lead furnace slag, are treated in a shaft furnace. The recovered zinc fume is leached separately. In the near future, the leaching residues are to be treated by a wet process, developed in the Company's own laboratories. Purification of solutions is accomplished in two steps: antimony and zinc dust are added in the first one, only zinc dust in the second one for removal of cadmium. Electrolysis cells are partly of a conventional type. A new type of cell configuration was put onstream in October, 1969, planned output 60,000 tpy. Main features of the new cell rooms are the fully automatic pulling, stripping and replacing of the jumbo-size cathodes (immersed area 2.6 m2). Zinc cathodes are remelted in induction furnaces followed by in-line automatic casting and stacking machines.

Jan 1, 1970

By Scott Turner

MY YEAR OF SERVICE as president of the A.I.M.E. came at a time when the mineral industry had suffered severely because of disturbed economic conditions throughout the world. The Institute, an integral part of this industry, had been similarly affected. Its membership and revenues decreased; it was confronted by problems of retrenchment at a time when its vigorous operation was especially important to its members, of some moment to the mining industry, and of value to the nation. Throughout the last year, the recession of activity in our industry continued with slight abatement. Your Board accordingly exercised such economy within the Institute as was possible without impairment of essential functions. It endeavored to aid in sustaining the morale of members, their sense of professional unity, and their interest in maintaining research and the interchange of scientific and technologic data upon which the progress of our industry depends. Effort was made to assist in the difficult task of finding employment for needy members; our endeavors have met with some success.

Jan 1, 1933

By William B. Millar

IN ONTARIO development of the gold mines is being rapidly pushed, while the intensity of the search for new mines has probably not been equaled at any time in the past. Even to outline the results of recent prospecting activity in Ontario would be a big undertaking, but it would be timely and, I hope, interesting to Institute members to review some generalities regarding the work of the prospector and then to discuss in some detail the growth of Ontario's most promising prospect area, the Swayze district, where serious mining operations are already under way. Probably no one writing about prospectors and pros¬pecting can resist hoping that his article will not reach the eyes of a certain portion of the uninformed general public and cause a further influx of "prospective prospectors" into any given area. It is somewhat mystifying how so many people reach the conclusion that prospecting is in

Jan 1, 1933

By Maurice Magee

The Ducktown ore deposits have been known, explored, and mined for 120 years. Eight massive sulfide ore bodies occur in highly folded and metamorphosed graywacke, graywacke conglomerate, mica schist, chloritegarnet schist, and staurolite schist of Precambrian age. The ore deposits are tabular bodies that have been extensively folded, generally conform to the enclosing rocks, but show local complex differences. The ore deposits, ranging in size from 250,000 tons to over 20 million tons, are composed principally of the minerals pyrrhotite, pyrite, chalcopyrite, sphalerite, and magnetite. Gangue minerals are quartz, calcite, actinolite, tremolite, hornblende, garnet, and masses of schistose wall- rock. Three fault systems are present that have influenced ore control and ore body configuration. Hydrothermal effects are evident in wall-rock alteration. Evidence of retrograde metamorphism is extensive in the wall and ore associated rock. Preliminary isotopic age dates have indicated four possible metamorphic events during the Paleozoic Era. Ore genesis is considered to be hydrothermal replacement of receptive beds, predominantly highly calcareous zones, quartzitic zones, and brecciated shear zones. Ore deposition is thought to have occurred during the Devonian Period, with later mobilization and recrystallization of the ore and gangue during Middle and Late Paleozoic times.

Jan 1, 1968

By K. L. Sutherland, J. Rogers

The relationships between collector and mineral, activator and mineral, and activator, collector and mineral will be considered herein. We propose to criticize current theories of flotation but we will not repeat the many pertinent arguments presented by Wark and Cox28 in 1937 in which the "chemical" or more strictly the "solubility" theory proposed by Taggart and co-workers22 is shown to be untenable. Recently Taggart, Arbiter and Kellogg24 have studied the long-chain aliphatic amines as collectors and have attempted to resuscitate the solubility theory for these particular collectors. Dean and Ambrose3 have felt that "we stumble over words" when we distinguish different mechanisms of adsorption. Our view is that nothing is more stultifying to the development of a science than attempts to force widely different phenomena into one classification. This oversimplification leads immediately to difficulties in the interpretation of results. Experimental Procedure The response of minerals to activator and collector was determined by "captive-bubble" tests. The methods of preparation of specimens26 and of testingin have been previously described. Results from captive-bubble tests were confirmed by flotation tests in glass-stoppered cylinders.26 The full lines shown in the figures relating solution composition to contact (flotation) distinguish solutions in which contact (flotation) is possible from those in which it is not. The curve is derived by successive approximation and the accuracy is ±o.2 pH units and ±5 mg. per liter of collector or depressant. Solution compositions for which it was shown experimentally that contact or flotation is possible are marked by a circle, those for which it is not possible by a cross and those for which it is doubtful by a cross within a circle. It is assumed that at all other solution compositions within (without) the curve, contact or flotation is possible (not possible). After testing in the collector solution, the mineral was removed, washed, and tested by the captive-bubble method in water, or floated in a cylinder with frother only. In this way the composition of solutions in which a mineral was conditioned but in which properties of the collector solution prevented contact or flotation can be defined. The composition of solutions in which conditioning was possible lie between the full and broken curve, the experimental results being indicated on the figures by a square. The curves show the limits of composition of solution in which flotation in a cell would be possible. Many factors other than those considered in these tests determine recovery or grade of a given mineral in practice.

Jan 1, 1947

By J. Rogers, K. L. Sutherland

The relationships between collector and mineral, activator and mineral, and activator, collector and mineral will be considered herein. We propose to criticize current theories of flotation but we will not repeat the many pertinent arguments presented by Wark and Cox28 in 1937 in which the "chemical" or more strictly the "solubility" theory proposed by Taggart and co-workers22 is shown to be untenable. Recently Taggart, Arbiter and Kellogg24 have studied the long-chain aliphatic amines as collectors and have attempted to resuscitate the solubility theory for these particular collectors. Dean and Ambrose3 have felt that "we stumble over words" when we distinguish different mechanisms of adsorption. Our view is that nothing is more stultifying to the development of a science than attempts to force widely different phenomena into one classification. This oversimplification leads immediately to difficulties in the interpretation of results. Experimental Procedure The response of minerals to activator and collector was determined by "captive-bubble" tests. The methods of preparation of specimens26 and of testingin have been previously described. Results from captive-bubble tests were confirmed by flotation tests in glass-stoppered cylinders.26 The full lines shown in the figures relating solution composition to contact (flotation) distinguish solutions in which contact (flotation) is possible from those in which it is not. The curve is derived by successive approximation and the accuracy is ±o.2 pH units and ±5 mg. per liter of collector or depressant. Solution compositions for which it was shown experimentally that contact or flotation is possible are marked by a circle, those for which it is not possible by a cross and those for which it is doubtful by a cross within a circle. It is assumed that at all other solution compositions within (without) the curve, contact or flotation is possible (not possible). After testing in the collector solution, the mineral was removed, washed, and tested by the captive-bubble method in water, or floated in a cylinder with frother only. In this way the composition of solutions in which a mineral was conditioned but in which properties of the collector solution prevented contact or flotation can be defined. The composition of solutions in which conditioning was possible lie between the full and broken curve, the experimental results being indicated on the figures by a square. The curves show the limits of composition of solution in which flotation in a cell would be possible. Many factors other than those considered in these tests determine recovery or grade of a given mineral in practice.

Jan 1, 1947

By Paul M. Tyler

MARKETWISE the year 1935 was rather a good one for most of the rare and minor metals; as a class they climbed out of the depression much faster than the common metals. The diamond market, too, was better than it had been for years, attributable only in part to investment buying, as there was a genuine pick-up in consumer demand. Wars and rumors of war tended to speed up purchases of certain metals, but consumption for peaceful purposes was the principal factor. Significant was the important role played by new industrial uses. New discoveries during the year were disappointingly few, considering the broad extent of this research frontier. Scientific developments were far from being at a stand-still, of course, but the dominant note was the cashing in on research consummated in former years. With even a moderate upturn in general business a surprising number of laboratory ideas donned overalls and found jobs in industry.

Jan 1, 1936

By William Campbell

(Cleveland Meeting, October, 1912.) [SECRETARY'S NOTE.-To avoid repetitions of foot-notes, references to authorities are made in the paper by means of figures, referring to a numbered list in the appendix.-J. S.] I. INTRODUCTION. IN the olden days the making of alloys was au art, and the secrets of the craft were jealously guarded. To-day it has become a science, though the old ideas in regard to the secrets and formula are dying hard. Modern progress may be attributed to scientific research and testing of materials, and the substitution of chemical analytical control for " cook-book " methods. We know to-day a great deal about the constitution of alloys, the reasons of the change in structure and physical properties by heat and mechanical treatment; and this new knowledge is due for the most part to the physical chemist and metallographist, who have shown us that alloys are simply solutions, and as such obey definite laws. The application of the theories of solutions and of the phase rule tells us what ought to happen when our alloys are in a state of equilibrium. The working-out of the temperature-composition diagram (thermal diagram) for numerous alloys has thrown a light on the structure and constitution which has dispelled most of the darkness in which we labored before the advent of metallography. The work began with the determination of the freezing-point curves, and here the research of Le Chatelier,1 Gautier,2 Roberts-Austen,3 and the other pioneers broke the ground. Next the physical chemists, Tammann,4 Rooseboom,5 Bancroft,6 and their colleagues, showed us the complete thermal diagram and its meaning. Then the researches of Heycock and Neville 7 on the Cu-Sn series and of Shepherd 8 on the * Associate Professor of Metallurgy, Columbia University in the City of New York.

Dec 1, 1912

By P. P. Gregory

ESTIMATION of re- serves in prorated sand fields has been discussed by S. A. Judson, H. D. Easton, Jr., and W. A. Schaeffer, Jr., in a paper that appears in Vol. 114 (1935), of the A.I.M.E. TRANSACTIONS. The purpose of this present paper is to extend the investigation to prorated flush limestone fields and to outline a method of procedure in determining the amount of oil originally in place and the amount of oil that can be recovered from such fields. Although it is possible to use the decline curves to estimate the amount of recoverable oil in certain limestone fields that are allowed to produce the oil at or near capacity production, such a method cannot be used in fields under severely restricted production rates. The problem is exceedingly complex due to fluctuation in the allowable rates of oil production over a wide range and at frequent intervals, and especially because of the heterogeneous nature of the reservoir itself. A well completed in a large solution cavity, capable of producing great quantities of oil per day, may be offset by a well of very limited capacity. Also, it is di5cult to arrive at an average figure for porosity in a given limestone reservoir due to abrupt variations in the character of limestone, in many instances even between two ad- joining wells. It is a safe statement that uniformity of porosity and permeability in limestone reservoirs .is nonexistent. It is evident, therefore, that the method of estimation of re- serves on the basis of per-acre content can give only approximate results.

Jan 1, 1935

By Nathaniel Arbiter

There is a history in all men's lives, Figuring the nature of the times deceas'd, The which observ'd, a man may prophesy, With a near aim, of the main chance of things. W. Shakespeare, Henry IV; Part 2 Introduction This nation's first century embraced two stages of the Industrial Revolution. During one, what had been a colonial agricultural economy began to industrialize; water power, then steam after 1794, were the energy sources; coal and iron were the essential ingredients. The second stage started after 1850; aided by rich and diverse mineral resources, the country began its transition from the Iron Age to the Age of Metals. Early civilizations had been built on stone, and fairly high levels were sustained on iron. But the spectacular advances in the past century in communication, in construction, in transportation by sea, rail, land and air, and in much that characterizes modern civilization have depended increasingly on the use of the complete metallic and nonmetallic resources of the earth's crust. Thus it was appropriate to define the Industrial Revolution as “the period during which man's relationship to natural resources became utterly changed”, 1 with minerals playing a major and indispensable role. But we are now becoming aware that the relationship of man to natural resources must change again. On every hand the dangers inherent in the contamination of land, sea and air by the wastes of civilization are becoming apparent. And from the growing realization that mineral wealth is finite must eventually come other far reaching changes in mineral use and distribution. For on the scale of centuries we cannot continue to exploit mineral resources even at present rates, let alone at expanded rates, without eventual depletion of the more abundant resources, and early exhaustion of the less abundant. In the past our problems were relatively easily met by the development of new and improved machinery and processes. But the future will

Jan 1, 1971

By L. Bombardieri, H. F. Mills

Iron King mine, producing gold-silver-lead-zinc-ore, is 10 miles east of Prescott, Ariz. At present the 1806 level is being developed. The echelon pat tern of ore deposit continues at depth but is less pronounced, and the orebody is now more or less continuous over 2600 ft of strike length, with widths 5 ft to as high as 26 ft where overlapping of lenses occurs in one section of the mine. Better continuity of ore at depth has encouraged systematic mining and improved plant facilities to offset higher operating costs. With favorable persistence of ore at depth, the three-compartment No. 6 hoisting shaft appeared inadequate to handle increased tonnage from greater depths, and in 1952, a four-compartment steel and concrete shaft was started. This is now at a depth of 1906 ft, and shaft pockets and loading cartridges are being installed on the 1806 level. Ore from the new shaft, hoisted in 5 ½ -ton Jeto bottom dump skips, is dumped into a 500-ton shaft bin, from which it is fed to a 16x30-in. gyratory crusher and conveyed 415 ft through an undersurface concrete gallery to the secondary crusher and conveying system supplying the 900-ton mill. Lead, zinc, and pyrite concentrates are floated, and the flotation tailings are cyanided after desliming. Waste from the new shaft is dumped into a 250-ton surge bin, fed from this bin to a 24-in. conveyor, and discharged into the glory hole above the block cave. The new shaft is served by a double-drum 400-hp hoist used for ore and waste; the No. 6 shaft conveys men and material.

Jul 1, 1956

By J. C. Bayles

Jan 1, 1885

By H. O. Hofman

With the exception of the exhaustive paper on the Father de Smet mill, by its designer, Mr. A. J. Bowie, Jr. (Bans., x. 87), nothing, so far as the writer is aware, has as yet appeared on the stamp-mills of the Black Hills of Dakota, although they have been steady producers for the last ten years. Within the small area of about 6000 by 1600 feet, $2,271,341.14 was produced in 1887† from rock averaging $4 per ton in free gold. I. The Ores. Character of the Ores.—The gold of the district is found in quartz and pyrites finely distributed through vast bodies of mica- and amphibole-schists, argillites and phyllites, and also impregnating the schists themselves. The " Belt," embracing the section of Lead City, Terraville and Central City, is the only part worked at present. The principal associated mineral is iron pyrites, with some arsenopyrite and chalcopyrite, garnet and asbestos. The ores from open cuts and upper levels are more free-milling. than those from underground workings below water-line. Hence

Jan 1, 1889

By B. C. Craft

Oil and gas development in Mississippi during the year 1933 was rather active and a number of important wildcat wells were drilled throughout the state. Mississippi showed an increase in drilling operations during 1933. There were 58 completions from 22 counties during this period, compared with 53 completions in 10 counties during 1932. The Jackson gas field in Hinds and Rankin counties continued to be the most active area with 26 completions, resulting in 17 gas wells, 2 oil wells, and 7 dry holes, compared with 38 gas wells, 1 oil well and 5 dry holes during 1932. A further attempt to extend the producing limits of the Amory gas field resulted in a dry hole. Extensive exploration in south Mississippi has proved the existence of ample source beds and presence of an extensive sandbody near the top of Cockfield. Core tests, supplemented by extensive geophysical work, have been carried on in Jackson, George, Harrison, Pearl River and Stone counties. Exploration will be continued in 1934. The most important deep test drilled in 1933, and the deepest well ever drilled in a southeastern state, was the Eastman Gardner et al., Bank of Seminary No. 1, sec. 26-8N.-15W., Covington County. This well went through about 1300 ft. of Selma chalk, and was abandoned in the Eutaw at 8004 ft. Another interesting operation during the past year was the Foster Creek Oil Corporation's Foster Creek Lumber Co. No. 1, sec. 14-2N.-2W., in the "Eastern Conroe Trend." This test is shut down at 3687 ft. in the Catahoula sandstone and has not encountered any important shows of oil or gas. A total of 107 of the 117 gas wells completed in the Jackson gas field since its discovery in 1930 are still producing, and have a combined open flow of approximately 3,724,896,000 cu. ft. It is reasonable to assume that this area will be rather inactive during 1934 as the maximum daily production during 1933 was 3,476,000 cu. ft. The 10 wells that have gone dead were edge wells. The water level is now between the sub-sea depths of 2190 and 2195 ft. The Gulf Refining Company's Rainey No. 1, sec. 13-5N.-lE., one of the early wells in the field, had gas and water at —2225 ft. That the field is under hydraulic control is

Jan 1, 1934

By AIME AIME

COMMITTEES. LOCAL COMMITTEE.-R. C. Crawford, Chairman; Harrison W. Craver, Secretary; Julian Kennedy, Taylor Allderdice, E. W. Pargny, Charles L. Miller, W. H. Rea, S. A. Taylor, M. E. Wadsworth, W. A1. Henderon, A. C. Dinkey, W. L, Jones, E. L. Messier, George Mesta, J. H. Jones, G. H. Riley, S. L. Goodale, D. W. McNaugher. LADIES' COMMITTEE.-Mrs. Taylor Allderdice, Chairman; Mrs. Julian Kennedy, Mr. R. C. Crawford, Mrs. E. M. Herr, Airs. J. W. Marsh, Mrs. T. A. Mellon, Mrs. G. P. Bassett, Jr., Airs. D. M. Clemson, Mr. Charles L. Miller, Mrs. V. L. P. Shriver, Mrs. W. A. Bostwick, Mrs. A. C.. Dinkey, Mrs. A. P. Childs, Jr., Mrs. F. R. Dravo, Mrs. Hermon Griffin, Mrs. W. H. Nimmick, Mrs. F. H. Lloyd, Mrs. S. G. Cooper, Mrs. S. H. Church, Mrs. E. N. Ohl. The Institute Headquarters was established at the Hotel Schenley, where a bureau of information was maintained for the benefit of the visiting members and guests of the party during the time of the meeting. TECHNICAL SESSIONS. The first session, held Tuesday evening, Mar. 1, 1910, in the large lecture hall of the Carnegie Institute, was called to order by Harrison W. Craver, Secretary of the Local Committee. Mr. Craver introduced Dr. John A. Brashear, who extended to the members and guests a hearty welcome to the city of Pittsburg, to which David W. Brunton, President of the Institute, responded. The following papers were presented in oral abstract by the authors: Biographical Notice of Dr. Charles B. Dudley, by Dr. R. W. Raymond, New York, N. Y. Biographical Notice of William Metcalf, by Col. II. P. Bope, Pittsburg, Pa. Development of Hindered Settling Apparatus, by Robert H. Richards, Boston, Mass. (Illustrated by lantern-slides.) A Few Mining Districts in the Argentine Republic, South America, by Z. S. Beyl. (Illustrated by lantern. slides.)

Apr 1, 1910

By Wilhelm Borchers

IN all special branches of the chemical and metallurgical industries, in which large electric furnaces became necessary for carrying out new processes or for the improvement of old ones, the development of the electric furnaces took place on much the same lines. The endeavors to make a success of a new idea brought forth many ingenious designs, which, however, almost without exception, furnished the proof that the safest and shortest way to practical success is the utmost simplicity of construction of the necessary apparatus. Our knowledge of the qualities of materials for building electric furnaces and of the constituents of the furnace-charges, especially their electric conductivity and their chemical affinity . towards one another at high temperatures, is still far from being complete, and from this fact we must conclude that the smaller the number of elements in the construction of a furnace, the fewer the number of unreliable factors both in the construction and in the operation of the electric furnace. This conclusion deserves special attention when an electric furnace for making steel has to be chosen from the constantly growing number of inventions, inasmuch as the chief con¬stituent of steel, the element iron, is a substance which in its liquid phase has so great an affinity fir those elements which are to be removed from the charge, that it is very difficult to comply with the following conditions: 1, to beat the refining-slag to the highest point of its chemical activity ; to prevent the iron from entering the slaw, or, where this cannot be done, to make it enter so that it finally appears in the end-product

Jan 1, 1910

By Renato G. Bautista, David C. Lindholm

The results of scale-up studies on a continuous, multistage horizontal mixer-settler extractor are presented. The chemical and mechanical system involves the separation of lanthanum from a mixture of rare earth chlorides using di(2-ethylhexyl) phosphoric acid as the solvent and dilute HCl as a scrub solution in a bench scale extractor. Each stage has a hold-up of 2.6 l. A single stage unit is utilized for scale- up studies. Results are obtained on four sizes of geometrically similar units, the largest being six times the volume of the original bench size. A unit operations technique is chosen so that mixing and settling can be examined independently. Variables examined include type of continuous phase, flow rate of inlet streams, and power input to the mixer. Inlet flow-rate ratios are kept constant for all tests. TWO potential methods of unbaffled pump-mixer scale-up are explored; the maintenance of constant impeller tip speed and constant power input. For the settler, the previously successful method of basing design on constant flow-rate per unit cross- sectional area is used.

Jan 1, 1977

By F. L. Sizer

SOME old-time views which have recently come into my possession have inspired me to record that part of the early history of Leadville, Color- ado, with which I am familiar, the years 1878 to 1882, in the hope that others will add to what is here mentioned. My first appearance in Leadville was in June, 1878, immediately after graduation from the University of Michigan, and I found a congenial and lively crowd of young men, already there. The old log hotel, at the corner of Pine and State streets, housed some distinguished guests in the summer and fall of 1878. It was my good fortune there to make the acquaintance of James B. Grant, afterwards Governor of Colorado, in July of that year, when we were both glad of the accommodation afforded by cots in the second floor loft of the hostelry presided over by Herman Hibschle. Grant was then building his smelter and our associates were Eddy and James, August R. Meyer, and Berdell and Witherell. The Grand Hotel-Harris and Walsh, pro- prietors-was the first-class hotel of the place; but in a very few months there were many competitors.

Jan 1, 1924

Discussion of the paper Of JAMES JOHNSTON, presented at the New York meeting, February, 1914, and printed in Bulletin No. 85, January, 1914, pp. 107 to 133. CHAIRMAN E. GIBBON SPILSBURY.-I would like to call attention to the fact shown in this paper that less than five years or perhaps seven years ago nobody had thought it possible to cyanide with success silver ores. The cyaniding of silver and gold ores was first of all started in Mexico, and gradually extended to this country in the case of the silver ores alone. The average extraction, I think, for the metals in Mexico, in the case of the silver ore, is less than 85 per cent., whereas here, in the case of a very complex ore, carrying a high percentage of sulphur and arsenic, and other objectionable elements, the ore has been treated so as to extract an average of 95 per cent. of the silver contents of the ore. It is really a phenomenal revolution in the metallurgy of silver ores which has been demonstrated and worked out at the Nipissing mines. GEORGE A. PACKARD, Boston, Mass.-I would like to suggest a slight modification, perhaps, of the statement which is made that no one considered cyaniding of silver ores up to five, or perhaps seven years ago, because in 1897, when I was at Mercur, Utah, one mill near there was operating on silver ores. It did not operate very successfully from a commercial standpoint, because they did not have a great deal of ore, but the extraction, I was told, was very satisfactory, and I am quite confident that it was, because, as suggested by the name, Chloride Point, the ores were silver chloride ores, and of course very easily soluble. Some years before that, in 1892, I made some tests myself. I spent three months making tests on more or less complex silver sulphide ores at Virginia City, Mont., and while our tests on the plain sulphide ores, finely ground, were quite successful, on account of the presence of a small amount of copper we did not work out a satisfactory solution of the problem at that time; although since then a cyanide plant has been erected and for at least eight years these ores have been treated by cyaniding at Virginia City, and the mill is still in operation. The period of five to seven years should, therefore, be modified considerably, in justice to the pioneers in the cyanide processes. REGINALD E. HORE, Toronto, Ont., Canada.-I hoped that there would be metallurgists from Cobalt here to present and discuss Mr. Johnston's paper. In their absence a few remarks from me may help to make clearer to you what they have accomplished.

Jan 6, 1914