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By C. W. Kovach, A. Moskowitz

Studies were undertaken to investigate the effects of manganese content on the machinability and other Properties of a free machining martensitic stainless steel (AISI Type 416). Machinability was found to be significantly improved in steels of high manganese content, and a direct relationship was obtained between machinability and steel Mn:S ratio. As the manganese content of the steel increases, the sulfide Phase present changes from CrS to (FeMn)Cr2S4 to (MnFeCr)S, and finally to MnS. The average sulfide inclusion hardness decreases through the same range of increasing manganese content. The mechanism for machinability improvement is discussed in terms of a soft ductile sulfide affecting deformation in the secondary shear zone. Type 416 containing relatively high manganese for improved machinability shows good general properties. The effects of increasing manganese content on mechanical properties, cold formability, and corrosion resistance are described. THE addition of sulfur is commonly used to improve the machinability of stainless steels. However, little attention has been paid in the past to the composition and characteristics of the sulfur-containing phase or phases present in these resulfurized steels. Recent information on the properties of sulfide phases, and their role in metal cutting, suggests that variations in these phases could have critical effects on machin-ability, as well as important effects on formability and other properties such as corrosion resistance. Manganese, chromium, and iron are strong sulfide forming elements present in stainless steels! of these, manganese has the greatest sulfide forming tendency and iron the least.1"1 The manganese content of resul-furized 13 pct Cr steels, often about 0.5 pct, can be insufficient or only barely sufficient to combine with the sulfur that is present; thus, the precise level of manganese can strongly influence the nature of the sulfide phase. Sulfide phases which may be present in stainless steels have been reported to include CrS, a spinel-type sulfide, chromium-rich manganese sul-fide, and manganese Sulfide.5,6 Detailed phase relationships for the Fel3Cr-Mn-S system have been reported by the present investigators,7 and a portion of this work will be referred to subsequently in this paper. Recent work by Kiessling6 and Chao et a1.8 has shown that sulfide phases can display wide variations in hardness, and may undergo considerable plastic deformation under isostatic loading.9-12 Early theories of metal cutting attributed the influence of sulfur to a lubricating effect. It is now apparent that the influence of the nonmetallic inclusions and their properties on crack initiation, deformation in the shear zones, and boundary films must also be considered in relation to the machining process. This paper presents the results of studies conducted to relate machinability to the various sulfide phases which occur in stainless steels. This work has led to the development of alloys with improved machinability, and has generated information on the effects of inclusions on metal cutting processes. Effects of sulfide inclusions and steel composition on other important metallurgical properties are also discussed. MATERIALS For drill machinability and inclusion studies, 10 lb laboratory heats were melted in an air induction furnace. These heats were made with sulfur contents be tween 0.10 and 0.50 pct and manganese contents be tween 0.05 and 3.0 pct. Residual elements were added to the heats in amounts typical for commercial steels. The typical compositional range covered by the heats is shown below: C Mn P S Si Ni Cr Mo Cu N 0.10 0.05 0.007 (M0 0.40 0.40 13.0 0.20 0.10 0.03 3.0 0750 The laboratory ingots were forged in the temperature range of 1800" to 2100°F to 3/4-in. sq bars, and all bars tempered to a hardness aim of 200 Bhn prior to testing. Because of differences in composition and tempering response, the tempered bars showed some variation in hardness (175 to 275 Bhn) as well as variations in delta ferrite content (0 to 50 pct). Composition, hardness, and delta ferrite content were considered in the analysis of the machinability data. Additional tests involving tool-life evaluation and determination of other properties were conducted on materials from commercially melted and processed 15-ton electric furnace heats. TESTS AND PROCEDURES Machinability of the laboratory heats was evaluated in a drill test. In this test, 1/4-in. diam holes, 0.4 in. deep, were drilled alternately in a test bar and in a standard bar for a total of four holes in each. This sequence was repeated three times using a freshly sharpened drill each time. The average time required to drill a hole in the test bar was compared to that for the standard bar. A drill machinability rating was assigned to the test bar relative to a rating of 100

Jan 1, 1970

By Edward Walsh

In the early history of the production of metallic iron from the native oxides or ores, success attended the labors of the workman according to the care he devoted to his work, and according to the degree of skill he possessed in furnishing the required amounts of fuel and ores to be acted upon by the blast propelled by the bellows, trompe, or wooden tub, and delivered into the hearths of the Persian, bloomery, or Catalan forges. The same skill may also have been of avail in the use of the lower forms of the ".Stück," "Blue,"or" Wolf"

Jan 1, 1887

The Institute is custodian of funds for support of numerous gold medals and prizes and has representatives on boards awarding still others. Details regarding the Institute Awards are given below. The Institute is represented on the boards of the John Fritz Medal, the Hoover Medal, and the Alfred Noble Prize, in conjunction with the three national societies of Civil, Mechanical and Electrical engineers; and, also on the board of the Washington Award, on which the Western Society of Engineers also is represented.

Jan 1, 1940

By John V. Beall, William F. Haddon

A long the mighty Andean Cordillera, there is splendor beyond imagination-in the natural beauty of the mountains and in daring engineering and lavish investment in the mines. This is the story of the great copper mines of Chile and Peru. Each mine has a special quality which has tested the physical and spiritual resources of the founder. In the early days of the older mines, the mining engineer of song and story was more the rule than the exception. He was physically tough, ingenious and a leader of men. In the current political and social environment of Chile and Peru, the foreign contract mining engineer is still needed; but he must be a different type of man. To John J. Selters at Cerro's Rio Blanco, the principal ingredient is still "toughness," but it is "toughness of mind" that is needed. "He probably should be a teacher." The copper mines are not new. They were, almost without exception, worked by Indians (La Exotica might prove the rule), and later by the intrepid Spaniards. Modern mining began after the turn of the century. In Chile, the first of the big ones was the Braden Copper Co. founded on the El Teniente deposit. This development was followed by Chile Exploration Co. at Chuquicamata and Andes Copper at Potrerillos. These properties have been developed over the years by vast expenditures of money and a monumental amount of labor. None was free of technical problems-metallurgy at Chuqui, marginal grade of the old mine at Andes, avalanches and the great fire at El Teniente. The evolution which has brought the established mines of Chile, and the new ones coming on stream, to their present state of development is in reality the work of wonders of input-money, engineering and responsible management in an atmosphere of political stability. Without any one of these, the result would have been failure.

Jan 11, 1969

By Carl R. Christiansen, James J. Scott

Advance mine planning, coupled with good mining practice, can be employed to develop underground space in stone mines for future industrial usage. To assure the developer the maximum return on his investment, initial planning should consider all aspects of the commercial operation, including surface layout, mining, and underground industrialization. The modular concept of mining to compartmentalize the space offers several advantages over conventional methods. Some expenditures can be considered as mining costs with a reduction of profit from stone production while lowering the capital requirements for conversion for usable space.

Jan 1, 1977

By Sidney Cornell

THE technical- advantages of adding oxygen to air and producer gas, or using it as a reactive agent, producing 400 B.t.u. gas instead of. the present 150 B.t.u., with higher flame temperatures and a reducing flame possible, with a smaller volume of gases passing through a furnace, will result in quicker melting, sharp working, and the production of a higher quality steel. Probably electric-furnace quality steel can be produced in an open-hearth furnace using oxygen. A modern, standard, 100-ton open-hearth furnace, with all equipment, costs from $350,000 to $500,000; there are about 1000 open-hearth furnaces in this country. When considering the use of oxygen in the open-hearth furnace, it is necessary to study: (1) The use of oxygen in the present furnaces, such that modification of existing furnaces and equipment cost the minimum, although the full advantages of oxygen are not thus obtainable. (2) The use of oxygen in a furnace designed for its use, producing quality and quantity steel at the lowest possible cost. This entails the junking of approximately one-half the value in existing equipment-writing off $250,000,000. The basis of such an estimate is the present cost of manufacturing open-hearth steel. Objection may be taken to some of the unit prices here given, but while some companies obtain their ores for much less, the prices quoted are -market price. They are used to show the maximum economy obtained by oxygen at that point.

Jan 11, 1924

By William H. Morris

At the Glen Summit meeting, the question of controlling the silicon in pig-iron WAS raised; and as this has been deemed by most furnace-men for years past a matter of special difficulty, an account of our experience in the matter may be of interest. When running on mill-iron, some years ago, we aimed to keep

Jan 1, 1893

By A. Beeby Thompson

FOR more than 2500 years, natural gas issues in the Surakhany district of the Apsheron peninsula were the object of pilgrimages by fire worshippers and Hindoos from Burma and India. Even as late as 1890, Hindoo priests conducted ceremonies in a temple at Surakhany, which probably replaced a more ancient one; but later, the visits of the pilgrims were prohibited in order to check the spread of Asiatic diseases in that region. For centuries, limited supplies of oil have been abstracted from shallow excavations in the Caspian oil belt and dispatched into the interior of Asia and elsewhere for medicinal and industrial purposes. Statistics show a yield of 37,400 bbl. in 1863, but only since 1869 has there been serious development; in that year the yield was 203,000 bbl. At that time, hand digging was supplanted by drilling, and the enormous wells that resulted from tapping sources hitherto beyond the reach of operators completely demoralized the industry for a time, owing to inadequate outlets for the products. The early activities in this area were greatly hindered by annoying taxation, monopolies, imperial land grants, etc., but when these were revoked or adjusted, in 1877, the industry sprang into prominence and, between 1898 and 1901, the Baku fields produced practically one-half of the world's supply of oil. Within a few miles of Baku lie the two richest oil fields in the world; viz., the Balakhany-Saboontchy-Romany and the Bibi-Eibat, the latter constituting almost a suburb of the city. For many years the gasoline obtained in the refineries of the Baku area was burned in pits, being considered an undesirable product, and until 1870 the residue also was destroyed, its value as a fuel not being recognized. Kerosene was the main product sought by the refiners. It was shipped across the Caspian Sea and up the Volga to the industrial centers of Russia. Only on the completion of the Baku-Batoum railway did the Baku oil fields secure

Jan 8, 1920

By George Langford

THE McIntyre mine is in the Pearl Lake section of the Porcupine gold area. The rocks are Keewatin lavas intruded by quartz porphyries and albitite dikes of Algoman age. Gold-bearing quartz veins are found in the Keewatin rocks near the porphyry stocks. The whole area has been highly compressed by forces acting along a N. 20°W. line. These forces folded the Keewatin rocks before the intrusion of the Algoman rocks, and later schisted both the Keewatin and Algoman rocks. Vein fractures were developed after the folding but before the development of the schist by the compres-sive forces being locally broken up into couples. These couples were set up by the differential resistance to deformation of porphyries and basalts, and also by the competency of the dacites and incompetency of the tuffs and fragmental rocks. During the important period of vein formation, two zones were developed-an inner productive zone in which the quartz veins are ankerite-bearing and an outer barren zone in which the quartz veins are calcite-bearing. The vein solutions originated in the same magma that supplied the albitite dikes.

Jan 1, 1938

By William Fink

MANY investigators have attempted to determine the true nature of the internal changes taking place during aging. Merica, Waltenberg and Scott1 were the first to propose a theory of age-hardening. They attributed the age-hardening of duralumin to the precipitation of minute particles of the compound CuA12. Later Zay Jeffries and R. S. Archer2 augmented the above theory by suggesting that the small CuA12 particles acted as "keys" causing "slip interference." Many other investi-gators3 have devoted much time to the mechanism of age-hardening, some corroborating the "precipitation" and "slip interference" theory, others coming to different conclusions because of effects that to them seemed unexplainable by the early theories; e.g., the increase of electrical resistance upon aging, the fact that no change in lattice parameter could be detected during the early stages of aging even at elevated tempera-tures, and the fact that the density did not change as would be predicted. In 1932, Merica revised4 his earlier precipitation theory to take care of these presumably anomalous effects. This revised theory, the "knot" theory, assumes that substantial age-hardening occurs before actual precipitation of solute as discrete particles. The assumed mechanism is one of diffusion of solute atones into groups forming distorted regions which act as "hard" spots and cause slip interference. These "knots" are assumed to have approximately the same lattice arrangement as the solvent.

Jan 1, 1936

By Frank H. Skelding

Still the world's largest producer, consumer and importer/exporter of minerals, the United States has, in recent years, become more and more aware of the many diverse forces that increasingly affect its ability to maintain free access to and trade in minerals, both domestically and abroad. The nation's growing dependence upon foreign sources of minerals in the face of mounting competition is causing many changes, not only in the mineral industries, but in national attitudes and policies as well. This paper examines the position of the United States in the world mineral economy relative to the significant trends that have and are developing. It attempts to define and evaluate the major present and future impact of these trends and to anticipate the probable effects upon the U.S. and its mineral economy.

Jan 1, 1976

By S. Razi

Injection luminescence of single crystals of rare-earth-activated CdS was investigated. Crystals of CdS:Nd, CdS:Er, and CdS:Yb, grown by the vapor transport technique, were suitably etched and hetero-junctions of Cu2S-CdS were fabricated on one side of the CdS substrate by chemical reaction. The device was then heated to 200°C in an inert atmosphere for 5 min. Static V-I measurements show that at low voltages (V < 1 v) the current is controlled by the junction, while at higher voltages the bulk Properties of the CdS substrate effectively control the current. Because of the large thicknesses no negative resistance was found. Reverse breakdown voltage varied from 5 v, for junctions that were not heat-treated, to 100 v, for diodes that received the proper heat treatment. The rectification ratio, measured in the range of 2 to 10 v, varied from 300 to 3000. Capacitance- voltage measurements indicate a weak dependence of the junction capacity on applied voltage. The capacity was found to increase appreciably with room light illumination. The variation of capacitance with frequency is indicative of a p+-i-n structure. An open-circuit voltage of 0.4 v was measured under an illumination of 100 mw per sq cm. Under forward bias, the bluish-green edge emission characteristic of CdS was observed. No sharp rare earth emission line was observed, which is in contrast to our results using ZnS:Tb, where, under high-voltage excitation, the rare earth emission was dominat over the lattice emission. The absence of rare earth emission implies that either the nature of the rare earth ion is different at the het-erojunction than in the bulk or the probability of energy transfer to the rare earth ion is small. RARE earth elements are playing an increasingly important role in the Synthesis of materials for a variety of purposes, e.g., solid-state lasers, color television screens, and so forth. Interesting systems result when wide-band-gap photoconducting lattices are activated with rare earths. A study of the lumines-

Jan 1, 1969

By J. B. Fisken

(Butte Meeting, August, 1913.) BEFORE touching upon the immediate subject of this paper a few facts of a historical nature as to the general application of electricity to mining might be of interest. As to what was actually the first application of electricity to mining, opinions will no doubt always differ. My experience does not go back far enough, nor are the records to which I have had access of any value as covering this point. Sydney F. Walker, a man whose pioneer experience in the application of electricity to mining purposes dates back as far as 1876, ,gave an interesting resume of the subject in an address before the South Wales branch of the Association of Mining Electrical Engineers at its 1.913 session, and, unless his statements are shown to be wrong, they should be accepted as facts. According to Mr. Walker, the ignition of charges of blasting powder was the first operation in mining to be accomplished with the aid of electricity. Very frequently this energy was furnished by a static machine and occasionally by a magneto generator. Later, this was followed by the application of electricity to bell signals, and we are told that this application was looked upon skeptically and regarded as an expensive experiment by the mining managers of those early days. At the Paris Exposition of 1878, there was exhibited an electric lamp, which suggested future possibilities to the mining engineers of those days. The first successful application of electric lighting to underground excavations that I have been able to find any record of is that of M. Blavier. In the year 1879&apos; he installed two Serrin lamps and successfully illuminated one of the large underground chambers in the Angers slate quarries. Another early application of electricity to the lighting of mines is that in the large chambers in the salt mines of Maros-Ujvár, in Hungary; these have been regularly and successfully lighted elec-

Jan 6, 1913

By Yves Dardel

The literature concerning the remelting of alunlinum and its alloys is very rich. Unfortunately the majority of the papers on this subject have no scientific value, for the theories or explanations are too often in opposition to the laws of physical chemistry. Furthermore only a few of the methods of purification are considered in the literature. Hence it has seemed necessary to the author to sketch a general theory of the purification of secondary aluminum. The purpose of the purification is to eliminate the impurities that the charges, and the atmosphere of the furnaces bring into the bath during the successive remelt-ings. Indeed scrap as well as metal can be used when soiled with oil, greases, water, or others, if it has been sufficiently dried and contains oxides. At the melting point of the metal, the oils and greases are decomposed into their constituent elements H², O2, H²O, co², CO, CH,, and others. These gases are added to the corresponding gases in the atmosphere of the furnace. The impurities introduced into the metal during the remelting will accordingly be the products resulting from the action of these gases on the liquid bath. The quantity of hydrogen that is soluble in aluminum and its alloys is given by the relation of sieverts3 as a function of its partial pressure PH2 in the atmosphere m = K vPH² [I] where K is a constant, which depends only upon the temperature and increases with it. The experiments of Rijntgen and Braun4, RÖntgen and M611er5, Bircum-shaw6 and Winterhagerl have rendered it possible to determine the value of K, when the temperature is less than 1.000°C. One obtains: log K = - 4,702.5T + o 238 [2] Besides its usual significance, the term Ph~ represents also the internal pressure of dissolved hydrogen, since in the equilibrium, that is1 when no gas exchange Occurs between the two phases, the Pressures of hydrogen in the metal and in the atmosphere must be equal. Eq I shows that when the partial pressure of H2 increases the amount of dissolved hydrogen in equilibrium increases, and that, if the contrary Occurs, the quantity of H² should diminish. However, if for any reason the diffusion of hydrogen is hindered and the total amount of dissolved gas remains constant while the temperature decreases, the internal pressure of H² increases until it reaches the value of the hydrostatic pressure. At this point, bubbles of hydrogen appear in the bath and escape out of it. The amount of hydrogen in the metal is then limited by a a depending On the hydro- static pressure, which is practically equal to one atmosphere. Indeed hydrogen does not accumulate in the form of a hydride appearing as a separate solid phase. However1 even the mechanism of the solubility is not yet elucidated. One does not know exactly as yet, whether the

Jan 1, 1949

By Robert G. Van Nostrand, John H. Henkel

TRANSIENT potentials obtained in resistivity prospecting can be separated into two classes. The first is electromagnetic, has a comparatively short time constant, and increases in relative amplitude as the electrode separation is increased. These electromagnetic transient potentials, of which an excellent theoretical treatment is given by Yost: are the result of changes in the current and can be classed as differentiated signals. The second class is electrochemical, has a comparatively long time constant, and decreases in relative amplitude as the electrode separation is increased. The electrochemical signals are generated by the current flow itself and can be classed as integrated signals. The transient potentials due to electrochemical factors are the subject of this article. The phenomenon is referred to as induced polarization. Schlumberger" was the first worker to observe induced polarization, but he was unsuccessful in attempts to apply the principles of induced polarization in electrochemical prospecting. Other workers, notably Bleil; have studied polarization and in some cases pointed out its possibilities, but no theory has been presented that describes polarization and its time dependence adequately. It is the purpose of this discussion to present the essence of a theory to geo-physicists and to show that it leads to results consistent with experimental evidence. The theory on which this analysis is based has existed in electrochemical circles since 1910."

Jan 1, 1958

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,&apos; which has become somewhat out of date, in view of the decade&apos;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

Shoemaker: We&apos;ve all heard a lot about epoxy liner backings. This brings up the question-do zinc furnaces still have a place in a new plant? Meaders: I would, you must understand, be prejudiced in this question because we introduced epoxy backing into the industry. Naturally, we wouldn&apos;t have done so if we didn&apos;t think it should be done. With that background maybe I could give a little more information on this particular subject than some of the others, because we now have been in this business for some three or four years.

Jan 11, 1967

By C. E. Shoenfelt

The year 1939 witnessed the rapid development of several of the more important Rocky Mountain oil and gas areas and the discovery of new oil and gas fields. As a further result of an active year, many oil fields had their productive limits greatly extended or responded to deeper drilling with oil production in lower horizons. In Colorado there was a substantial increase in refinery capacity, with three new units constructed. Its contribution to the crude-oil supply was an important extension of the producing area of a Western Slope field and a deeper oil-producing horizon in an old field east of the Front Range. Occurrences of gas were reported in two wells in northwestern Colorado, but severe winter weather prevented tests and the value of these discoveries cannot be determined at this time. Montana&apos;s northern fields were extended and a number of record wells were completed. The North Cut Bank area gives promise of wide expansion in 1940. The gas-producing area of Wyoming&apos;s Elk Basin field was extended into Montana on the north plunge of the anticline. The most important developments in Wyoming oil fields in 1939 were extensions to the producing area of Lance Creek and the discovery of a deeper pay in the Tensleep formation at Wertz dome. A new gas field at Horn Valley in the south central part of the state was the only new field discovered, but wildcatting was at low ebb in Wyoming in 1939. Colorado In Colorado, the year 1939 saw the completion of several interesting tests, but largely with negative results. Oil was discovered, however, in a deeper sand in the old Fort Collins field and the productive area of the Wilson Creek field was extended. Gas had been noted in two Western Slope wells, at Yellowjacket-Buford and at Trull, but their volumes had not been determined at the end of the year. Of principal interest, however, were the failures, descriptions of which will be given presently. One of these established a new depth record for Colorado.

Jan 1, 1940

By C. E. Shoenfelt

The year 1939 witnessed the rapid development of several of the more important Rocky Mountain oil and gas areas and the discovery of new oil and gas fields. As a further result of an active year, many oil fields had their productive limits greatly extended or responded to deeper drilling with oil production in lower horizons. In Colorado there was a substantial increase in refinery capacity, with three new units constructed. Its contribution to the crude-oil supply was an important extension of the producing area of a Western Slope field and a deeper oil-producing horizon in an old field east of the Front Range. Occurrences of gas were reported in two wells in northwestern Colorado, but severe winter weather prevented tests and the value of these discoveries cannot be determined at this time. Montana&apos;s northern fields were extended and a number of record wells were completed. The North Cut Bank area gives promise of wide expansion in 1940. The gas-producing area of Wyoming&apos;s Elk Basin field was extended into Montana on the north plunge of the anticline. The most important developments in Wyoming oil fields in 1939 were extensions to the producing area of Lance Creek and the discovery of a deeper pay in the Tensleep formation at Wertz dome. A new gas field at Horn Valley in the south central part of the state was the only new field discovered, but wildcatting was at low ebb in Wyoming in 1939. Colorado In Colorado, the year 1939 saw the completion of several interesting tests, but largely with negative results. Oil was discovered, however, in a deeper sand in the old Fort Collins field and the productive area of the Wilson Creek field was extended. Gas had been noted in two Western Slope wells, at Yellowjacket-Buford and at Trull, but their volumes had not been determined at the end of the year. Of principal interest, however, were the failures, descriptions of which will be given presently. One of these established a new depth record for Colorado.

Jan 1, 1940

By A. Keith Brewer

RECENT advances in the fields of chemistry, biology, and metallurgy have confronted the analytical chemist with an entirely new set of problems. Development of plastics and synthetics has brought about a need, not only for adequate methods for their analysis but also for the various raw materials entering into their manufacture. The remarkable advance made in biochemical and agricultural research resulting from the use of isotopes as tracers or "tagged atoms" has established the necessity for the development of methods for the concentration of natural isotopes and for a means for their analysis. Similarly the advent of new and complex alloys calls for accurate analytical methods. Fortunately the analytical chemist has been able to meet some of these new demands by adapting to his purposes an instrument which has long been the most exclusive toy of the physicists. Solubility and the chemical properties of the atoms, which have always served as the basis for chemical analysis, do not enter into this new technique. Instead, momentum, defined as mass times velocity, is utilized as the means for the separation of atoms or mass groups.

Jan 1, 1946