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Executive Committee. GEORGE F. KUNZ, Chairman. E. GIBBON SPILSBURY, Vice-Chairman. THOMAS ROBINS, H. J. SEAMAN. Louis D. HUNTOON, Secretary-Treasurer. Meeting, Apr. 4, 1913. A joint meeting of the New York Section of the American Institute of Mining Engineers, the American Society of Mechanical Engineers, and the American Institute of Electrical Engineers was held in the large auditorium of the Engineering Societies Building, 29 West 39th Street, on Friday evening, Apr. 4, 1913, and an exhibition of the Edison Talking Moving Pictures was presented before the Societies, together with exhibitions of the work which is being done by the Edison Co. in making moving pictures to illustrate lectures on natural science and the useful arts for school and college work. Introductory remarks were made by Mr. J. W. Lieb, Jr., and followed by an exhibition of moving pictures illustrating the formation of crystals, the operation of different types of pumps, magnetic forces, electro-magnetic separation of iron ore, the evolution of the fly, and many other most interesting studies. One of the films, entitled The Formation of Crystals, showed a moving picture of a boy, whose laboratory was the kitchen, dissolving salt in a test tube filled with hot water. The boy then poured the solution of hot salt into a watch glass and placed it under the microscope to watch the crystals form. This film was immediately followed by another showing what the boy saw through the microscope. The solution at first was free from crystals. Gradually the crystals commenced to form and increased very rapidly after once starting, shooting across the screen with lightning speed. The film illustrating the separation of iron ores by the Edison electro-magnet showed an ore bin with an electro-magnet set at one side and below the bin. As the ore was dropped from the bin the magnetite was drawn into the. electric field and deposited in a separate rile from the sand.

Jan 5, 1913

By George W. Bain

SOME problems concomitant with commercial exploitation of marble are presented as examples of interesting, useful and profitable fields for application of scientific knowledge. The marble industry is only one such field and is selected because its varying new aspects are familiar to the author. However, what is true for marble is equally so in principle for many industrial minerals. The problems of any stone industry are to maintain markets, create new outlets for stone already in demand, and develop varied uses for varieties that are not so popular. Here the geologist has a different role from most of his colleagues in metal mining. The producing branch may ask about the expectable variation in thickness or size of a deposit as development proceeds. The stock department may call for the available amount of a given type of stone before accepting a large order. The sales force requires data on the use for stone from certain parts of deposits in order to divert grades to the most suitable use. The service department wants defects rectified and the cause determined to avoid recurrence. The mills want data on durability and cutting quality of abrasives. The geologist occupies no special department; he is on general call, as may be illustrated by a few types of problems that may be classified as: (1) dominantly geological in character, (2) dominantly chemical in character, (3) dominantly physical in character. GEOLOGICAL PROBLEMS The geological problems deal almost exclusively with the size of blocks. Size across the deposit is limited by thickness of individual beds, and along the strike by the space between crosscutting joints. Frequently the vertical depth of a block is reduced by exfoliation shells arising from spontaneous expansion. All these factors require consideration in developing a deposit to fill an order. Thickening of Marble Beds The limestone beds that became the marble deposits of the northern Appalachians and of the Yule locality in Colorado were seldom homo-

Jan 1, 1940

By C. M. Weld

The southeastern coast of China, from Ning-Po to .Macao, represents an element in the continental mass of Asia which has at practically all times in the remote past exhibited a tendency to rise rather than to subside.' This strip of land, 1,000 or more miles long by perhaps 150 miles wide at its widest part, has in fact stood above sea level since at least early Cambrian times, while the great basins to the north and west were receiving their massive accumulations of Sinian (Cambro-Ordovician), Carboniferous, and later deposits. We find, .therefore, a coastal fringe of metamorphic and igneous rocks bordering the huge expanses of sedimentary rocks which occupy the interior. Hong-Kong is situated toward the southwestern extremity of this fringe. Hong-Kong is an island of approximately 30 sq. miles, on the north shore of which is situated the city of Victoria, with its 325,000 inhabitants. This island was ceded to Great Britain in 1842. In 1560 the peninsula of Kowloon (about 5 sq. miles), being that part of the mainland lying directly across from the city of Victoria, was added to Hong Kong. Thirty-eight years later, in 1898, a stretch of territory, including the mainland behind Kowloon and. numerous adjacent islands, was leased to Great Britain for 99 years. This last addition is known as the "New Territory of Hong-Kong" and comprises 376 sq. miles in area. A map of Hong-Kong, Kowloon, and the "New Territory" is shown in Fig. 1. My studies of this total area of over 400 sq. miles were devoted primarily to an investigation of the mineral resources. Systematic mapping of the immensely complex exposures of rocks was not possible in the time at my disposal. However, observations in, this. direction warrant a few generalizations.

Jan 2, 1914

By M. B. Yung

Location THE Fu Chuan district lies near the eastern boundary of Kwang Si province in southern China and is connected with the coast by the West river and its branches. The Journey The first part of the journey from the coast is made very comfortably in one of the West river steamers which runs to Wuchow, the great distributing center for tile whole province. From here there are two ways of reaching the Fu Chuan district. One is to drop clown the West river for 15 miles and ascend the Yuen river for 120 miles. The other is to ascend the Fu river, which joins the West river at Wuchow, and at Ping Lok tike chairs across country. Of the two the former is the more direct and shorter but for other reasons I chose the latter. At Wuchow one must provide his own means of transportation, which may be a native boat anywhere up to 40 ft. in length, but not over 18-in. draft. The method of working these river boats against the swift current which in many places develops into rapids is interesting and worthy of note. Tracking along the bank with the tow line attached to the mast head is the most common procedure, but poling, sculling, sailing and winding up the rapids by a windlass are used as the case may require. The boatmen are the hardiest set of fellows I have ever seen often putting in 15 hr. of the most exhausting labor. The average clay's run against the current is 15 miles. On this trip one should have his own food, bedding and servants, and a guard of 10, or more soldiers is almost a necessity as certain parts of the river are infested with pirates.

Jan 9, 1914

By Paul M. Tyler

YEAR after year, the kaolin industry of the United States has been setting new production records and making better products. High-grade paper, pottery, and rubber clays are produced in this country mostly in the South. Georgia alone contributes over 70 pct and South Carolina almost 20 pct of the total domestic output. Residual kaolin is mined in North Carolina, highly plastic but naturally sandy Tertiary (Eocene) potting clays are worked in north central Florida, and good white clays are produced in several other states, but the main sources of kaolin or china clay have been numerous deposits in the Tuscaloosa (Upper Cretaceous) formation. This formation of generally sandy sediments is called the Middendorf member in older geologic reports and corresponds in age with some of the New Jersey clays. As shown in fig. 1, it crops out almost continuously in a generally southwesterly direction across South Carolina and Georgia and into Alabama. Clay is mined from this formation in all three states but the principal producing centers lie within about 10 miles of a straight line drawn between Aiken, S. C., and a point about 10 miles south of Macon, Ga. The white kaolins of the South were recognized and used prior to the Civil War but suitable treatment processes were not introduced until World War I when imports, chiefly from England, were curtailed. Although imports of high-grade clays were resumed after 1918, the domestic industry managed to treble its prewar production record during the early 1920's and has continued to grow. Whereas the 1909 to 1913 average total production in the United States was only 132,104 short tons valued at $705,352 f.o.b. mines, the output in 1948 was 1,568,848 tons worth $19,756,738.

Jan 6, 1950

By Hewitt Wilson

CHALK is soft, pulverulent limestone formed from calcareous remains of microscopic organisms. Whiting is the powder made by the fine- grinding of limestone. Although European chalk dominated the early American market and is still shipped to the eastern and western seaboards, the domestic producer, by new technical processing, improved equipment, and proper selection and mixing of raw materials has shown that the United States can be independent of foreign sources. DISTRIBUTION European Chalk-Outcrops of Cretaceous chalk are found in the area roughly bounded by Antrim, Ireland, on the east, East Prussia on the west, Sweden and Scotland on the north, and Nice, France, on the south. Commercial chalk is mined from the chalk cliffs between Dover and Hull, England; from deposits near Mons, in the Departments of Pas de Calais and Nord in northern France; and from similar de- posits in Denmark and Belgium. United States-Some grade of limestone is found in every state of the Union, but true chalk of Cretaceous age is limited to three large areas in the central and southern states. Niobrara (Cretaceous) chalk outcrops are found as a narrow band encircling the Black Hills in South Dakota, Wyoming, and Nebraska, and in much larger exposures in southeastern South Dakota, eastern Nebraska, and western Kansas. A third chalk belt extends from west central Arkansas into Oklahoma and connects with the Austin beds, which almost cross Texas. In the southeastern states, the Selma chalk extends from western Tennessee south through northern Mississippi and turns east across central Alabama. Most of the domestic chalks are discolored with iron oxide or carbon. Some marls can be included with chalks of commercial possibilities. Some of the soft, cream-colored limestones of northern Florida, Georgia,

Jan 1, 1949

By Dr. T

THE application of electricity in the extraction of metals has hithcrto been chiefly confined to the electrolysis of dissolved or fused compounds of these by varios methods. The power of electric currents to generate intense heat in their passage through a resisting medium has, however, long been known, and the late W. Siemens thereby succeeded in fusing considerable quantities of steel. But it was reserved to Messrs. Eugene 11. and Alfred H. CoWles, of Cleveland, Ohio, to take a new step in the metallurgic art by maKing the heat thus produced a means of reducing in the presence of carbon the oxides not only of the alkaline metals, but of calcium, magnesium, manganese, aluminium, silicon, and boron, with an ease that permits the production of these elements and their alloys with copper and other metals 011 a commercial scale. In the apparatus devised and now employed by the Messrs. Cowles, a column of fragments of well-calcined charcoal, so prepared and arranged as to present the requisite electrical resistance, is imbedded horizontally in finely pulverized charcoal, and covered by a layer of the same material coarsely broken, the whole being arranged in a box of fire-brick, covered with perforated tiles and opened at the ends to admit two carbon electrodes an inch and a half in diameter.

Jan 1, 1886

By Robert Hunt

(New York Meeting, February, 1913.) I HAVE frequently stated that while the chemical composition of steel is important, yet even greater importance is connected with the mechanical and heat treatment of the metal. During the past year I encountered such a positive example of that fact that I deem it worth putting upon record. A prominent railway system divided an order for open-hearth steel rails between two steel works, both of which are under the control of the one corporation; giving to one about 18,000 tons, and to the other 7,500 tons of the same section and to be made under the same specifications. The rolling results obtained in the two mills varied so widely that a study of the figures is intensely interesting and serves to illustrate the advantages obtained by careful ingot casting, and, quite as pertinently, the possible benefits of careful subsequent heating and rolling with moderate reductions in the rolling process. The smaller order was rolled complete in four installments during the same months that the larger order was being made in six separate installments; but, to permit of exact comparisons, the totals of the four installments (completing the order with the mill which I will call A) are given with the totals of the first four installments of the larger order, made by the mill designated as B. These rolling results are:

Jan 5, 1913

By H. A. Schwartz, A. F. Gorton, H. R. Payne

In a previous paper1 we published what we believed to be a correct stable equilibrium diagram for an iron-carbon alloy containing + 1.20 per cent. silicon. The purpose of the present paper is to record the results of studies concerning the effect of silicon on the location of the eutectoid points of both systems, including also certain incidental observations of general interest. We prepared white cast irons containing roughly 21/2 per cent. carbon, 0.05 per cent. manganese, and 0.03 per cent. each of phosphorus and sulfur, but of accurately known silicon contents which varied from 0.40 to 3.32 per cent. These were completely graphitized, and both A1 points determined, as in our previous work, the specimens being converted from the stable to the metastable condition and vice versa by appropriate heat treatments. Each stable alloy was heated to a few degrees above Arl for 3 to 7 hr., quenched and analyzed for total and graphitic carbon, the difference being the "combined" or, better, agraphitic2 carbon content of the saturated solid solution just above the eutectoid transformation. One specimen was lost through accident, and the 0.40-per cent. silicon material gave an anomalous result ascribed to difficulty in maintaining the stable system in the presence of but little silicon.

Jan 1, 1923

By H. R. Payne, A. F. Gorton, H. A. Schwartz

In a previous paper1 we published what we believed to be a correct stable equilibrium diagram for an iron-carbon alloy containing + 1.20 per cent. silicon. The purpose of the present paper is to record the results of studies concerning the effect of silicon on the location of the eutectoid points of both systems, including also certain incidental observations of general interest. We prepared white cast irons containing roughly 21/2 per cent. carbon, 0.05 per cent. manganese, and 0.03 per cent. each of phosphorus and sulfur, but of accurately known silicon contents which varied from 0.40 to 3.32 per cent. These were completely graphitized, and both A1 points determined, as in our previous work, the specimens being converted from the stable to the metastable condition and vice versa by appropriate heat treatments. Each stable alloy was heated to a few degrees above Arl for 3 to 7 hr., quenched and analyzed for total and graphitic carbon, the difference being the "combined" or, better, agraphitic2 carbon content of the saturated solid solution just above the eutectoid transformation. One specimen was lost through accident, and the 0.40-per cent. silicon material gave an anomalous result ascribed to difficulty in maintaining the stable system in the presence of but little silicon.

Jan 1, 1923

By J. Intrater, E. S. Machlin

In a study of grain boundary sliding in superpure Copper (99.999 pct),&apos; bicrystals of a specific shape were used, Fig. 1. That shape was adopted in order to minimize the deformation of grains on both sides of the boundary due to clamping. Another requirement was to obtain bicrystals with a rnicroscopically straight boundary, Fig. 2. Single crystals of predetermined orientation (growth axis parallel to <310>) were grown in a graphite mold from seed crystals. The apparatus for growing single crystals consisted of a vacuum system, argon purification train, vycor tube (in which a graphite mold was placed), a carriage for the induction coi1,and a Lepel (7-1/2 KW) high-frequency converter. The graphite mold was heated by induction and the charge in turn was heated by conduction. The induction coil was moved by means of a motor at a speed of 1 1/2 in. per hr. Single crystals of two different orientations were grown from the melt in one-half of a split graphite mold, Fig. 3(a). Two such crystals were then placed in contact with each other in another split mold, Fig. 3(b) using tapered inserts. The pair of crystals was then remelted starting 2 in. from the top to insure that the whole top portion of the crystals was maintained molten. By moving the induction coil

Jan 1, 1960

By E. I. Larsen, A. S. Doty, F. R. Hensel

The alloy under discussion is a Pig. I shows results of heat-treating tests nickel-silicon bronze and is one of many on two typical nickel-silicon bronze castings age-hardening or precipitation-hardening of the type on which the observations were copper-base alloys. The hardening constituent is a nickel-silicon compound.l The quenching temperature necessary to produce hardening by a subsequent aging treatment is a function of the composition and extends from about 700°C. to 950°C.; the aging temperature range extends from 4000 to 600°C. The work carried out by the authors of this paper was confined to cast alloys having compositions within the ranges of: 1.5 to 3.00 per cent Ni; 0.4 to 0.75 per cent Sj: balance. comer. made. A quenching temperature of 750°C. produces almost as high a hardness on subsequent aging as do quenching temperatures of 850&apos; and 900°C. Several foundries have spent years of active and intelligent effort in trying to control the casting and heat-treating variables of nickel-silicon bronzes and finally gave up the attempts because of the inconsistencies of results.2 This undesirable characteristic was not manifest in the ultimate hardness or conductivity but primarily in tensile strength and ductility, as shown in Table I. The variation in tensile properties was often much greater than that existing on the alloys

Jan 1, 1941

By T. H. Courtney, G. W. Pearsall, J. Wulff

The mechanism, of the decrease in transition temperature of Nb3Sn was studied. Presintered Nb3Sn powder compacts were heated in a dynamic vacuum at elevated temperatures. Loss of tin resulted from these heat treatments and transition temperature as a function of tin loss was discontinuous at a critical value of tin loss. In general, decreases in transition temperature were correlated with deviations from AS a class, the A15 structure-type (also known as Cr3O or ß W) compounds have the highest superconducting transition temperatures.&apos; In this class are stoichiometry and presence of vacancies in niobium sites. The effect of vacancy distribution on the physical properties of Nh3Sn is considered. It is concluded that the close-packed atomic A chain in the A3B A15 structure must be preserved both in coutinuity and direction if good superconducting properties are to he obtained. tempting to associate these high transition temperatures with the most unique crystallographic feature of the A3B structure: the three close-packed, orthogonal chains of A atoms.&apos;0"&apos; There are at least three principal mechanisms by which the perfection of these "A-atom chains" could be interrupted: changing stoichiometry, inducing disorder, or introducing vacancies. Departures from stoichiometry in either direction in V3Ga lower the transition temperature.7&apos;8 In niobium-

Jan 1, 1965

By A. S. Doty, E. I. Larsen, F. R. Hensel

The alloy under discussion is a Pig. I shows results of heat-treating tests nickel-silicon bronze and is one of many on two typical nickel-silicon bronze castings age-hardening or precipitation-hardening of the type on which the observations were copper-base alloys. The hardening constituent is a nickel-silicon compound.l The quenching temperature necessary to produce hardening by a subsequent aging treatment is a function of the composition and extends from about 700°C. to 950°C.; the aging temperature range extends from 4000 to 600°C. The work carried out by the authors of this paper was confined to cast alloys having compositions within the ranges of: 1.5 to 3.00 per cent Ni; 0.4 to 0.75 per cent Sj: balance. comer. made. A quenching temperature of 750°C. produces almost as high a hardness on subsequent aging as do quenching temperatures of 850&apos; and 900°C. Several foundries have spent years of active and intelligent effort in trying to control the casting and heat-treating variables of nickel-silicon bronzes and finally gave up the attempts because of the inconsistencies of results.2 This undesirable characteristic was not manifest in the ultimate hardness or conductivity but primarily in tensile strength and ductility, as shown in Table I. The variation in tensile properties was often much greater than that existing on the alloys

Jan 1, 1941

By A. C. Fieldner

ASH in coal has always been regarded as an undesirable substance, as the heat content of a coal decreases in direct proportion to its ash content. It represents so much inert material that has to be transported, handled when the coal is burned, and finally disposed of. W. R. Roberts, in an address before the Engineers&apos; Society of Western Pennsylvania, Pittsburgh, on Sept. 29, 1925, said that on an annual output of five hundred million tons of coal, a reduction of 3 per cent. of ash means fifteen million tons of refuse and a decrease of $30,000,000 in freight charges. Ash also often prevents efficient utilization of the coal through the formation of clinker caused by the melting of the ash constituents when subjected to heat. The mineral constituents of coal may be of such nature as to make the coal unsuited for specific uses, as for instance, high-sulfur coal for making metallurgical coke. While the usual proximate analysis of coal gives the amount of ash, it gives no information as to the nature and composition of the ash nor of the mineral constituents from which the ash is produced. For the efficient washing of coal to remove ash-forming constituents it is desirable to know the composition and distribution of the ash-forming constituents. Obviously such information is also desirable for the most efficient utilization of coal.

Jan 1, 1926

By R. S. Archer

THE name molybdena was employed by Pliny to denote various substances resembling lead. Later this name was applied to galena-the naturally occurring sulfide of lead-or substances of similar appearance. By the middle of the eighteenth century, it was applied to graphite and to the mineral sulfide of molybdenum (MoS2) now called molybdenite. This confusion is quite understand- able inasmuch as these substances look and feel very much alike. In 1778, the Swedish chemist Scheele published a treatise in which he pointed out essential differences between graphite and molybdenite. On treatment with nitric acid, molybdenite, unlike graphite, produced a peculiar white earth with acidic properties which he called molybdic acid. Since the same mineral gave off sulfurous fumes on heating, he concluded that it was a sulfide of molybdenum. In 1790, there appeared an account of the isolation by P. J. Hjelm of the new element molybdenum, as a metallic powder, by heating the oxide with carbon. It was not until Bertelius conducted the necessary experiments, about 1818 to 1825, that the foundation of the chemistry of molybdenum was laid. The only recorded use of molybdenum during the first century after its isolation was as a chemical reagent, primarily for the determination of phosphorus. It was not until the last decade of the nineteenth century that the use of molybdenum in steel appears to have been investigated. A

Jan 1, 1953

By Wallace E. Johnson, Leslie R. Hill

As part of a continuing study of intense energy effects on the earth, such as explosive cratering for Plowshare, large scale hydro- dynamic computer codes which numerically integrate the two-dimensional mass, momenta, and energy conservation equations have been adapted for use on geological materials. Experimentally determined nonlinear dynamic equations of state and constitutive equations governing material strength are incorporated into a two-material Eulerian code, DORF. With the use of this code, impact studies have been made of projectiles with arbitrary shapes in the r,z cylindrical plane normally incident on semi-infinite half-space targets. The impact of projectiles on rocks has been studied empirically and experimentally; however, this paper employs a theoretical approach. Particular examples selected involve the impact of aluminum and iron projectiles on oil shale at velocities of 0.5 and 1.0 cm/µsec. These studies offer a quick and economic means to edit quantities unavailable in an experiment and to independently study the effect of varying parameters such as material shape, density, and strength, and impact velocity. Results reveal early time agreement with experimental high-speed photography as seen in the bowl-shaped crater and spray. Initial impact pressures at the projectile-target contact are in close accord with the one-dimensional Rankine-Hugoniot relations for the impact of dissimilar materials. These equations require local continuity of pressure and particle velocity across the interface and were found to hold locally, quite independent of projectile shape. Essentially all projectile energy is transferred quickly to the oil shale target (tens of microseconds). Over 75% of the original kinetic energy

Jan 1, 1971

By C. M. Tucker, Kent R. Van Horn, W. P. Sykes

RECENT investigations of the molybdenum-carbon alloys have been reported by Becker and Ebert1‡, Westgren and Phragmén2, T. Takei3, and H. Tutiya4. Takei3 studied the Mo-C system by employing metallographic and X-ray methods, and the other publications described the determination of the crystal structure of the molybdenum carbides. In exploring this system by a technique previously applied to the tungsten-carbon series5, the results of Takei were confirmed with two definite exceptions; i.e., first the composition of the eutectic, and second the nature of the carbon-fish intermediate phase. Consequently, a more thorough examination of the molybdenum-carbon constitution was initiated in an effort to correlate the data supplied by the microstructures, diffraction patterns and chemical analyses. METALLOGRAPHIC INVESTIGATION A briquette of molybdenum powder when heated in a carburizing atmosphere at 1500° to 1600° C. for several hours develops the carbon-rich layer shown in Fig. 1. The carburization was accomplished by placing the briquette in a carbon tube, which was heated in the hydrogen atmosphere of an alundum muffle wound with tungsten resistor. While the macrostructure indicates two distinct shells, and suggests the possibility of two carbon-rich phases, no evidence of this condition could be detected by the microscope, which revealed but one high-carbon constituent. This carbide forms next to the molybdenum as a relatively

Jan 1, 1935

By L. W. McKeehan

THE occurrence of twins in large ferrite crystals, made by a new process, was reported in a recent note. This paper describes a typical case of such twinning and suggests, on the basis of the observed facts, why smooth slip-planes are rarely observed in this metal. METHOD OF PREPARATION The material In which the crystals here dealt with were grown was made from 1/8 -in. Armco iron welding rod containing C, 0.04; S, 0.037; P, 0.003; Si, 0.008, and Mn, 0.02 per cent. This rod was cold drawn into wire about 1 mm. dia. A piece of this wire was supported vertically and was locally heated in hydrogen at atmospheric pressure to about 1400° C. by an alternating current (60 cycles per sec.) of about 35 amp., passed through it between a pair of travelling contacts about 8 cm. apart. The rate of travel for the case in hand was 12 cm. per hr. After some 30 cm. of the length of the wire had been heated and cooled in this manner the whole wire was immersed for a few seconds in dilute nitric acid, not restrained by alcohol. Etching was continued until, as nearly as could be judged by eye, the original smooth cylindrical surface of the wire was no longer capable of specular reflection.

Jan 1, 1927

By Shun-ichi Satoh

A NEW method of treating steel by ammonia has recently been intro¬duced into the metallurgical industry, by means of which piston cylinders of internal combustion engines, shafts and other similar steel products can be made more resistant to wear than formerly. In 1929 the writer&apos; published the historical notes and some experiments upon nitrification. He believes that the corrosion of nitrified steel is a matter of importance and worth studying; and as there have been few studies thereof, he has conducted experiments in this respect. L. Guillet,2 in 1927, reported corrosion tests made on nitrified and cemented steels with acid and salt solutions. In 1928, 0. Hengstenberg3 reported the high resistance of nitrified steel to water vapor and air. V. 0. Homerberg4 stated that nitrified steel has high resistance to water, air and salt solution; and G. Hagg5 studied nitrified layers of iron by means of the X-ray. Though F. Hanaman6 in 1913, measured the single potential difference of steel treated with ammonia at above 650° C., no one, it seems, has ever measured the single potential difference of the so-called nitrified steels having extraordinary hardness. The writer measured the single potential differences of nitrified special steels in various solutions with the object of studying the corrosion problem and, if possible, of knowing whether any new physical property would be caused by nitrification.

Jan 1, 1932