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By Eli Follett

It is indeed gratifying to note the marked improvement in the methods used in the coal- mines today compared to the methods in earlier days. Away back in the decade of 1900 to 1910 many of the mines were conspicuous for their absence of sprinkling and humidifying systems, as a result much of the natural moisture was absorbed by the dry air current and carried out of the mine and the mine was left dry, dusty and dangerous. This dangerous condition was intensified by large accumulations of fine coal dust on the haulageways where fire flashed from poorly lubricated rollers and bullwheels-trip riders used a torch with a flame reaching to the back of their necks, and large supplies of blasting powder were kept in the mines. Accidents and disasters were very frequent as we, in our ignorance flirted with danger. Staggered by the numerous accidents, and the nature of them; men began thinking along lines of safety, they worked out schemes and after many disappointments succeeded in having, some very whole some legislation enacted covering coal mining operations only to find that much lawlessness was still being practiced by the miners whom they sought to protect; step by step these safety men forged ahead, enlisting the co-operation of a few men about the mine whom they called a safety committee, until, today, we have an ironclad mining law which all have to respect. We have sprinkling and humidifying systems, the miners electric lamp, permissible explosives and many other devices making for greater safety in the operation of our coal mines. Our mines are no longer veritable gasometers and powder storehouses, as I. knew them to be in South Wales, Britain, where I started to work in the mines. Instead, the mines of this day are healthy, well lighted and ventilated workshops and too much cannot be said in the praise of safety engineers who, fought altruistically in their efforts to bring about the wonderfully improved conditions in the coal mines of this day. While the possibility of a mine fire starting, in these days of scientific mining, is remote every one admits there still exists a possibility and to deal with a fire, should one start, most coal miners are equipped with fire extinguishers. Extinguishers of all designs conceivable are on the market, the different extinguishers are charged with different chemical substances, Some are charged with patented chemicals and others with baking soda and sulphuric acid and so on, however, many of them are equipped with about eighteen inches of rubber hose and bear the conventional "FOR FIRE-TURN UPSIDE DOWN" but nothing is said to indicate how close it may be necessary to take the extinguisher to the fire before doing the "TURN UPSIDE DOWN" act, neither is anything said as to what effect the contents may have upon the' hands, face or body of operator should he come in contact with the liquid, nor is any warning given as to the dangers in the fumes which may come from the contents of the extinguisher in contact with the fire.

Jan 1, 1922

By William E. Ford, Edward Salisbury Dana

I. Anhydrous Chlorides, Bromides, Iodides; Fluorides. II. OxycMorides ; Oxyfluorides. III. Hydrous Chlorides; Hydrous Fluorides. The Fourth Class includes the haloids, that is, the compounds with the halogen elements, chlorine, bromine, iodine, and also the less closely related fluorine.

Jan 1, 1922

By C. W. Burrows

The burden a man can endure depends on its magnitude and the number of times it is applied, as well as on many other factors. The resisting power of steel likewise is dependent on many factors. The maximum load it can support indefinitely is much less than its possible momentary burden. A light load straining the metal far within its elastic limit, if repeated indefinitely, ruptures the metal. The magnitude of the stresses that may be alternately applied and removed without rupturing the material depends on the number of repetitions of the cycle; the intervening periods of rest; the thermal, electric, and magnetic conditions, as well as the presence of secondary streessses. While we are unable to formulate the law between the magnitude of repeated stresses necessary to produce rupture and the length of time during which these alternating stresses may be applied before rupture, my experience is that the time increases as the magnitude of the force decreases, according to a law which! to a first approximation, is exponential. In other words, F = Ce-t where F= magnitude of alternating stresses; t= time for which stresses are continued; C = constant, which depends on the conditions under which the operations are carried out. It is quite probable that the same type of law holds for the magnitude of a continuous force and its duration. When a rod of steel is subjected to the blows of a drilling hammer several things happen. First, one end is struck by the hammer and the other end is driven into the rock, thus causing a bodily displacement of the entire material of the steel drill. The greatest stresses involved in this bodily displacement are located at the two ends of the steel and manifest themselves by the distortion of these parts. Second, after the blow has been delivered, the steel drill, due partly to its own resiliency and partly to the resiliency of the rock, experiences a vibratory motion as a whole, this motion is quite similar to the bouncing of a rubber ball thrown violently upon a smooth pavement. Third, the free vibration of the drill is determined only by its own natural period of vibration. This motion involves all the characteristics of any vibrating body emitting sound. Certain elements of the rod will experience alternations of condensation and rarefaction and, in these regions, the individual steel

Jan 1, 1922

By F. F. Sharpless

IT IS to be. read in Western newspapers that Hon. S. S. Arentz who introduced H. R. 7736, 'has repudiated it, that certain mining men in Utah and Nevada say that they will fight it "until hell freezes over." It is to be read in more temperate expressions that "the eminent engineers who drafted the bill exhibited a woeful misunderstanding of Western sentiment and opinion." Furthermore, it is averred that there is no need for revising the mining laws, that we have got along pretty well under the existing laws, etc. Such statements are so surprising in view of, the facts of record that it is hard to believe that the oppon-ents of the bill, who make them, are well informed, or that they represent general opinion. It will be useful therefore to review the record of the case. Our GOOD OLD MINING LAWS We have indeed got on well in our mining industry, but that has not been by virtue; of our good old mining laws. Rather has it been in spite of them. Ever since the Richmond-Eureka case in the '70s there has been litigation arising from them. Early in the '80s the apex law was discarded by common consent in Leadville, and it has been ignored in every district of flat-lying ore deposits ever since. The great mines of the present time are the porphyry copper deposits. At Bingham, Ely, Ray, Chino, Miami, Clifton and Ajo the apex law is simply inapplicable. A law that is inapplicable to the modern conditions of mining may be an old law, but it can not properly be characterized as a "good" law. For such reasons, and many others of weight, there has been a demand for revision of the mining laws; dat-ing ,back at least three decades. President Roosevelt appointed a commission to advise respecting the question, said commission comprising. Dr. James Douglas (chairman), John Hays Hammond, D: M. Barringer, Walter B: Devereux, and William B. Mather. This committee was unanimous on the following points:

Jan 1, 1922

By John W. Roberts

The Federal income tax law permits as a deduction in determining net income "in the case of mines,... a reasonable allowance for depletion and for depreciation of improvements, according to the peculiar conditions in each case, based upon cost, including cost of development not otherwise deducted: Provided, that in the case of such properties acquired prior to Mar. 1, 1913, the fair market value of the property (or the taxpayer's interest therein) on that date shall be taken in lieu of cost up to that date." The law provides for a reasonable allowance but the regulations provide for a definite method of computation that possesses more the virtue of simplicity than that of reasonableness. Article 210 of Regulations 45 reads: "When the cost or value as of Mar. 1, 1913, or within 30 days after the date of discovery of the property shall have been determined, and the number of mineral units in the property as of the date of acquisition or valuation shall have been estimated, the division of the former amount by the latter figure will give the unit value for purposes of depletion, and the depletion allowance for the taxable year may be computed by multiplying such unit value by the number of units of mineral extracted during the year." This is simple, but is it reasonable? The intent of the law is clearly that the cost of the ore in the ground shall be considered as part of the cost of the same ore when removed and sold. The regulations fail to carry out that intent, because of the unwarranted assumption that all the ore in the mine cost the same amount per ton. This is what gives the Treasury Department's method its simplicity, but at the same time robs it of its reasonableness because the assumption is contrary to fact. It is self-evident that a ton of ore near the surface or exposed by present workings is worth much more than a ton buried so far down in the earth that it cannot be removed for many years. If no improvements in mining methods were expected, the value of deeply buried ore would be further reduced by the greater expense that would be required to

Jan 1, 1922

By D. N. Witman

One of the special uses to which the electric furnace has been put recently is the melting of an alloy of nickel and cast iron for the production of electrical-resistance grids. The metal sections of these grids, Fig. 1, are quite uniform for each pattern, but there is, among the various patterns, a variety of thicknesses. The cross-sections vary from 1/2 by 3/16 in. to as small as 1/8 by 1/8 in. The electrical resistance of a perfect casting lies within 10 per cent. above or below the fixed listed resistance for each pattern. Good molding is essential to success in the making of these grids, for with absolutely correct metal, a variation of 0.01 in. in width and thickness of section on some of the patterns may mean as much as 12 or 14 per cent. variation in resistance. The service for which these castings are intended demands that the metal, even in the smallest castings, be very soft, showing an open, gray, highly graphitic structure, in order that they may be resistant to shock, and stand up well under rough usage. The metal used for this purpose is a gray iron alloyed with 4 to 5 per cent. of nickel, which element, when the composition of the alloy is correct, imparts toughness and pliability to the metal and helps to overcome the tendency of metal to run white and become brittle because of the rapid cooling action of the sand mold. When cold, these castings can be twisted into various shapes, taking a permanent set without breaking. The alloy has approximately double the e1etrical resistance of ordinary cast iron. The metal specification is as follows: Per Cent. Silicon............................................. 2.40 to 2.60 Sulfur............................................. Under 0.05 Phosphorus......................................... Under 0.08 Manganese......................................... Under 0.40 Total carbon....................................... 3.60 to 4.00 Nickel............................................. 4.00 to 5.00 Copper............................................ 0.50 to 0.70

Jan 1, 1922

By H. W. Seamon

The data here given were obtained by 1500 tests made by the United Verde Copper Co. to determine the most economical air pressure for the operation of hammer drills under the varying conditions of use, and to investigate the variation in drilling speed at different air pressures. Twelve models of drills were used at gage pressures ranging from 40 to 130 Ib. No effort was made to harmonize theory and practice; but rather to formulate empiric rules that would cover the average variation of the results obtained. These rules on the performance of hammer drills, based on the air pressure as the main variable, however, are not necessarily of universal application, but they apparently satisfy the results obtained in this series of tests. The drilling conditions at this property vary widely; an average of twenty-one machine shifts to a 3-ft. (0.9-m.) round has been found necessary in some of the development work, while an advance of 56 ft. has been made in seven shifts in the "oxide" ground. This range precludes the adoption of one type of drill as a standard; consequently almost every kind of hammer drill sold in this country has been tested. At present, sixteen models are in use, of which two types of the heavy (150 to 160 lb.) mounted drills, one of the light mounted drill, one stoper, and two hand plugging drills are considered as standard. Method of Conducting Tests All machines were of the wet type, and were selected as being representative of the several types in use at this property; all had been in use from two to four months except the Waugh 66 and the Sullivan DX61, which were new. All machines were thoroughly overhauled before they were sent to the testing ground. Tests were made on the following machines: Ingersoll-Rand, No. 248 Leyner-Ingersoll, No. 18 Leyner-Ingersoll, No. 26 Baby Leyner, BCRW430 Jackhamer, and CCW11

Jan 1, 1922

By William E. Ford, Edward Salisbury Dana

The NATIVE ELEMENTS are divided into the two distinct sections of the Metals and the Non-metals, and these are connected by the transition class of the Semi-metals. The distinction between them as regards physical characters and chemical relations has already been given (Art. 453). The only non-metals present among minerals are carbon, sulphur, and selenium; the last, in one of its allotropic forms, is closely related to the semi-metal tellurium. The native semi-metals form a distinct group by themselves, since all crystallize in the rhombohedra1 class of the hexagonal system with a fundamental angle differing only a few degrees from 90°, as shown in the following list :

Jan 1, 1922

By Joseph A. Norden, A. R. Willson

Much has been written concerning the hoisting equipment of various mines throughout the country, but most of the literature on the subject, if not all, describes equipment of extraordinary capacity and the small and medium-sized outfits have been neglected. The hoisting equipment here described is capable of handling about 1200 tons per day. It has not been worked to capacity, but 600 to 700 tons, together with men and materials, have been handled in two shifts without any great effort. Only one shaft extends from the surface to the lowest levels of the mine; see Fig. I. It is composed of three compartments, two of which are used for hoisting, and the third for water, air, and electrical lines, and for sinking purposes. In 1909, this shaft was raised from the 1000-ft. (304-m.) level to the 700-ft. There a station was cut and an air hoist installed. At this time all mining operations were confined to the upper levels of the mine; that is, above the 700-ft. The ore was dropped to this level through chutes from the 300-, 400-, 500-, and 600-ft. levels and then lowered in cars on cages to the 1000-ft., which is the main haulage adit, the mill and railroad bins being about 3000 ft. from the shaft. Orebodies were, in due time, developed on the 1000-ft. level and below. Therefore, in 1913,the shaft was sunk to the 1150-ft. level and thereafter sinking was continued at regular intervals until the 1500-ft. level was reached. But, hoisting from the 1300-ft. level was a difficult and slow process with the antiquated air hoist, so, in 1916, it was decided to raise the shaft to the surface and install a modern, electrically operated hoist. This was completed early in 1917 and the hoist was in operation in March of that year. The Hoist Figs. 2, 3, and 4 show various features of the hoist and electrical equipment. A Nordberg engine of the double-drum, geared type, designed for a 10-ton load, including rope, at a speed of 1500 ft. per min., is used. The drums are 7 ft. (2.1 m.) in diameter, with a 54-in. (137-em.)

Jan 1, 1922

By Howard Scott, Henry S. Rawdon

The method of demonstrating the structure existing in a metal or alloy at high temperatures, by etching a polished sample after it has been heated to the desired temperature, is quite familiar to metallog-raphists. The usual procedure1 2 is to heat the specimen, previously polished for microscopic examination, to the desired temperature, in a neutral atmosphere (hydrogen or nitrogen), then admit the etching gas (chlorine, hydrochloric acid or similar gas) for a few seconds, and finally, after flushing out the etching gas with the neutral one, cool the specimen in the neutral atmosphere. The pattern produced by etching at a definite temperature is usually taken as a record of the microstructure prevailing at that temperature. It has frequently been pointed out that changes in composition of the surface metal occur during the preliminary heating in the neutral atmosphere, so that the appearance produced by the etching at high temperature may not exactly represent the condition of the interior of the specimen. To overcome this uncertainty, the heating has sometimes been done in vacuo,3 the etching gas being admitted when the desired temperature was reached, then pumped out and the specimen cooled in vacuo. The studies of Rosenhain, Humfrey, and other workers 4, 5, 6, 7, 8 dem-

Jan 1, 1922

By Frank H. Kingdon

and eventually we would have trouble. That is, these little localized overstresses may not be important if the structure is loaded a few times, but may be important if the structure is loaded many thousands of times. The existence of localized stress has been demonstrated by direct experimentation with delicate extensometers by the elaborate investigations of Coker. Localized stresses four, five, and six times those that we would get by the ordinary laws of mechanics exist in most of our structures. These stresses, ordinarily, under steady load do no damage but if they are repeated many times may start progressive failure. So far, we have seen no failure that could not be explained by localized high stress at a nick, a crack, a point where one heat treatment stopped and another began, or where there was local faulting, or any one of a dozen causes. In the case of drill rods, the actual distribution of stress must be different from that which any mathematical analysis could predict. It would seem that the spread of damage from the localized overstresses, so far as we can see now, explains the phenomenon known as fatigue. The Ideal Drill Steel By Frank H. Kingdon The essential qualities of a drill steel are: (I), It must be easily forged; (2), the forged bit end must permit easy heat treatment to obtain hardness to resist chipping; (3)) the bar or body must be stiff to resist bending or twisting and yet tough to resist shock and vibration, with resulting breakage, (4), the forged shank end must be easily heat treated to obtain hardness with great toughness. Minor requirements are that the bit and the shank are in alignment with the body; that the shank is of the proper shape and length and the shank collar or lugs of the proper diameter and length; that the hole is free from obstruction; that the striking end of the shank is flat and square; that the bit is of the proper shape, with the cutting and reaming edges formed full and to the required size; that the reaming edges are concentric with the axis of the steel, and that there are no sharp corners at the shoulder where the bit blends into the body. The essential qualities of a bit, are: That its shape be such that maximum cutting speed can be maintained for as great a distance as possible before wear of the gage and cutting edge reduces the speed of penetration to a point where a change of steel is made necessary; that the size or diameter of the drill hole corresponding to the gage of the bit can be maintained with the least possible reduction as the depth of the hole increases, and that the bit can be correctly and readily formed and heat treated. The following features of bit design require attention: Shape,

Jan 1, 1922

THE writer of this paper well realizes that the majority of engineering and metallurgieal works have from time to time evolved mechanical devices which are of great value as regards application in an operating plant.Many of these deviees would not be apparent to an individual making a brief inspection of works such as these, and it is for this reason that the writer proposes to outline a few of the devices which have been evolved by the engineering department of the Broken Hill Associated Smelters Pty. Ltd.NOVEL METHOD OF MACHINING A SPHERICAL JOINTFig. 1 represents one half of a casing for a ball-joint coupling. In the ordinary methods of boring an external spherical casing, that is with a radius bar attached to the tool rest of a lathe, there is always an error in the bore. It has two flat sides, and this error is inherent in the ordinary orthodox method and cannot be corrected. The engineers of the Broken Hill Associated Smelters Pty. Ltd. undertook a job that had to be extremely accurate, and the tool shown in Fig. 2 was evolved. The tool is not exactly fool proof, but in the hands of an average mechanic an absolutely perfect FIG. 1. sphere can be bored. The casing has to be held in the lathe in such a manner that one half can be removed without affecting the setting of the work. The business end of the tool is then placed inside the...

Jan 1, 1922

By Oliver Bowles

[In an endeavor to promote greater efficiency in the lime industry, the United States Bureau of Mines is preparing a series of preliminary reports dealing with particular problems of the industry. Through the circulation of these reports, it is hoped that sufficient interest may develop among lime-plant operators to prompt them to discuss with the bureau their our experiences with these problems. By such an interchange of ideas, it is believed that conclusion may be reached which will be of practical benefit to try entire industry. The first report, "Stripping problems it Limestone quarries of the Shenondoah Valley", Serial No. 2401, was issued during October, 1922. This report t is the second of the series. It is hoped that may operators will contribute additions to the information now at hand.]

Jan 1, 1922

By F. B. Foley

With the possible exception of high-speed tool steel, the service demanded of rock-drill steel is probably more precarious than that of any other tool steel. Unaided by the helpful influence of alloys and dependent solely on the efficiency of the heat treatment applied for its ability to stand up under the abuse to which it is necessarily subjected, rock-drill steel is worthy of intensive study. For its heat treatment the smith has his fire, an oil fire perhaps, and a quenching bath; he judges the temperature by his eye. There are shops where excellent drills are produced by this method, but there are more where the product varies between very good and very bad. Pyrometers with specially designed equipment are used in but few cases. But the responsibility for rock-drill failures does not rest entirely on the smith. Little has been published concerning the efficiency of drill steel, though the Canadian Mining Journal1 published the breakage record of a large number of hollow drill steels. This record indicates that most of the breaks occur during the early life of the steel and that as a given batch of steel is used, its percentage of breakage decreases. This fact, the article points out, is at variance with the much-talked-of theory concerning failure from crystallization and fatigue. It seems to point to the fact that the greater part of drill-steel failure from breakage is traceable to faulty manufacture, resulting in defects in the bore of the hollow steel from inclusions of slag or oxides, etc. As this defective material meets with early failure, it is weeded out. In addition, some breakage may be caused by a lack of proper condition with respect to heat treatment of the steel as furnished by the manufacturer. In the article mentioned, the breakage of 1/14-in (3.17 cm.) hollow steel is given as 4.62 per cent. for the early period of use, with a decrease to 3.35 per cent. and 2.67 per cent. with time in use. For 1-in. (2.5 cm.) hexagonal hollow steel, the figures for breakage are 0.18 per cent. and 0.06 per cent.; attention is called to the great decrease in breakage by the use of smaller diameter drills. The figures are given as so many drills sharpened, but there is no way of determining the percentage of

Jan 1, 1922

By John Bevan

In a discussion of the personal dangers that may arise from mine gases, it is necessary to take into consideration the gases which may result from an underground fire, or a fire in or about the downcast shaft, and the methods of avoiding or minimizing the danger arising therefrom. In all cases of the combustion of carbonaceous material such as coals and timber, carbon dioxide and water vapor are formed. In cases where the air supply is limited, some carbon monoxide is produced, the quantity varying with the readiness with which the oxygen from the air can get into intimate contact with the consuming carbon; in addition to these products there may be produced large volumes of irritating fumes consisting of unconsumed vapors' distilled from the burning material. Apart from the physical distress that may be caused by the irritant action of the fumes, the chief danger to life underground arising from a fire in or about the downcast shaft or intake airways is due to the carbon monoxide which the smoke is almost certain to contain. The physiological effects of this gas have already been discussed in mining papers and ref¬erence should be made to this. The prevention of fires at the surface near to the mouth of the downcast shaft, or in the shaft itself, or at the bottom of the shaft, usually lies outside the duties of the fireboss. An outbreak of fire at such places would, however, immediately foul the air current passing into the mine, and, assuming the men were in the mine, create a situation demanding urgent attention of the fireboss. As a rule, each case of fire creates its own problems, but in all cases the guiding principle should be to restrict the poison-laden 'air to the smallest part of the mine that is practicable, by opening separation doors, or breaking down selected stoppings at the most accessible points near the seat of the fire, so that the gases and smoke may pass directly into the return and so to surface. In the case of a shaft fire it will have the effect of fouling both shafts and in the case of a fire in an intake airway, both roadways leading to the shafts. It requires the use of some judgment. Therefore, in circumstances as to whether men inside the mine should attempt to escape to the shafts or should remain in the mine, and attempt to protect themselves from the poisonous air by suitably short circuiting the air-current and retiring from the main air-ways. In order to make such restraint easier, it is very desirable that all mines should be equipped with telephone communication from all sections of the mine to the surface so that men in the mine may be informed of what is being done at the surface to secure their safety, or instructed as to what they themselves should do. In cases of fire in or about the shafts, the question of the reversal of the air-current will probably arise. Should this be decided on by the management at the surface, the fireboss in the mine may have to give some attention to the effects which this action will have on the circulation of the

Jan 1, 1922

By L. C. IlsLey

Briefly, a permissible schedule of the Bureau of Mines establishes certain minimum standards for safety; it gives details of test methods adopted to determine whether these standards have been met, and a list of charges for such tests. Any manufacturer has the privilege of submitting his product for test in accordance with the conditions outlined in the schedules. His action is wholly voluntary, for the Federal Government has no jurisdiction as to what equipment shall be used in mines, this authority being left to the various States. When the product of a manufacturer has met the schedule requirements, he is permit¬ted to advertise this fact and to attach an approval plate with the bureau's seal to each machine he makes that is identical in every way with the equipment tested, inspected, and approved by the bureau. This work of approval has grown by the addition of new schedules until at present a great many mines are using one or more classes of permissible equipment, and there is still a demand for other approved apparatus in the ever-widening field of electrically operated machinery. The safety of electrical equipment of this type depends on four fundamentals, namely, (1) correct principles of design; (2) proper assembly of parts at the factory; (3) proper assembly and installation of equipment at the mine; (4) and proper operation and maintenance after installation. The first two factors are within the province of the manufacturer. The bureau either inspects and tests several models of one product, such as electric cap lamps, or one model, such as an electric motor. If this series of tests proves satisfactory, the manufacturer is given the privilege of making other appliances, and assembling them in the same way; the approval plate he attaches is his guaranty that the equipment is identical with the one tested and inspected by the bureau. The third and fourth factors concern those who use such permissible equipment, and it is to them that this paper is mainly addressed, in an effort

Jan 1, 1922

Jan 1, 1922

By Lewis C. Karrick

In studying the destructive distillation or pyrolysis of oil shales, the primary consideration is to determine the effects of heat on the organic components of the shale. The impracticability of separating these organic components, collectively known as "kerogen", from the mineral matter with which they are associated renders the problem extremely complex. The behavior of the kerogan in the shale while undergoing the heating process is probably different from that of the same kerogen if it could be isolated and treated under similar temperature conditions, and in fact the results of actual distillations have shown that the physical properties of the mineral matter in the shale may be the cause of much variation in the products of retorting. It must be remembered that the inorganic .material of the shale is a heterogeneous mixture of minerals solidified into a very close-grained compact mass. This mineral mass has a thermal conductivity different from that of the kerogen, thus complicating the problem of even distribution of heat. Furthermore, the temperatures of dehydration of gypsum end some; hydrous silicates are included within the temperature range of the shale distillation, These minerals are frequently present in the shales; and the evolution of water vapors from them will affect the partial pressures of the hydrocarbon vapors evolved from the kerogen, probably tending toward, the improvement of the quality of the oil distillates. Carbonates and sulphides which are also frequently present begin to decompose within this range of temperature, and the gases produced from them may alter the chemical constitution of the oils produced from the kerogen.

Jan 1, 1922

Jan 1, 1922

By Richard S. McCaffery

This paper considers certain aspects of the acid bessemer process, particularly in its relations to the duplex process—that combination in which the pig iron is first desiliconized and decarburized in acid bessemer converters and then dephosphorized in basic open-hearth furnaces. The acid bessemer process employs an acid-lined converter and produces an acid slag. The blow is usually thought to eliminate the silicon and manganese as oxides and then to burn off the carbon as carbon monoxide On account, however, of the relatively large amount of metallic iron present in the converter, compared with the relatively small amount of the impurities it is desired to oxidize, the first reaction in the converter probably is the formation of iron oxide, which dissolves in the bath and acts as an oxygen carrier for the silicon and carbon. As soon as iron oxide is dissolved throughout the bath, the oxidation of silicon commences; but in the early stages of the blow the mass law would indicate that iron oxide must form first, and this oxide probably increases up to some saturation point. The molten metal in the converter from the early stages of the blow right through to its completion remains basic, while the slag produced is siliceous. This fact is shown by the corrosion of the acid bottom and the tuyeres, which is greatest at the tuyere orifice where oxidation is most active and where there is the most iron oxide. Why does this acid bottom corrode? Because it is attacked by a base. The thought, therefore, suggests itself, why not. make the bottoms of basic or neutral material?' As the converter slag is acid, those parts of the converter coming in contact with the slag should be acid; but those parts of the converter that are in contact with the molten metal saturated with metallic oxides should be basic. or neutral. Bessemer operators have for some time tacitly admitted this condition, for the blast pressures have steadily increased with the object of keeping the metal in suspension, and so preventing bottom corrosion; if the molten metal were not basic, it would not attack an acid bottom. In addition, the tuyeres are bunched together at the middle of the bottom and a clear space is left around the outside of the bottom; if tuyeres are placed too near the side walls the

Jan 1, 1922