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By M. D. Cooper

LUCIEN EATON, Ishpeming, Mich.-It is not the custom in the Lake Superior region, as far as I know, to employ shot-firers. Each man, or pair of men (most of the contracts are given to two men) do their own firing; each contractor keeps his powder separately. The general custom is to distribute powder (dynamite only is used) to the mines 2 days a week. The boxes, marked with the contract number and the level, are taken underground and the men take them to their working places. They are kept in boxes, which must not be nearer together than 50 ft. and are usually away from the timber roads or traveling roads. When holes have been drilled, one man usually takes down the machine, and the other man makes up the charge. He cuts the fuse, puts in the caps, etc., at a distance from the powder box. He then carries the powder charges to the working place where both men charge the hole. They do their own firing and warn others coming from any direction that the holes are being fired.

Jan 4, 1917

By G. Aertsen

THE CHAIRMAN (HENRY D. HIBBARD, Plainfield, N. J).-This excellent paper fills a gap in our Transactions and is most acceptable. In the early days another way of casting tire ingots, sometimes called cheeses, because of their shape, was to use a 22-gage sheet-iron cylindrical can for each ingot of the proper size to give the weight desired. These cans were bottom cast in groups, usually of four, each can being surrounded by a heavy iron ring somewhat taller than itself the top of the can being covered by a circular cast-iron plate having a small conical riser in the center, about 2 ½ in. in diameter at the bottom and 10 in. high. The top plate was clamped down to resist the upward pressure of the fluid metal and the space between the can and the outer ring, usually about 2 in. wide, was filled with dry sand. The riser permitted the escape of some of the air displaced by the steel and also increased the pressure in the steel when the mold was filled, and so diminished somewhat the tendency for gas holes to form. But little was known of segregation and pipe in those days, though the center of an ingot was understood to be the worst part, and it was separated in part in the disk which was punched out in perforating the ingot. This disk was about 8 in. in diameter and from ¾ to 2 in. thick, the variation in thickness being to rectify the weight. When an ingot was too -heavy, a thicker disk-was made by not driving the punch in quite as far as when the ingot-weight was right. Then the bloom was turned over and the punch driven in on the other side, which finished the punching and detached the disk. The tire bloom was then" becked" and later reheated and rolled as described in the paper. The forging was done with a 10-ton double-acting steam hammer. The steel generally speaking had lower carbon, from 0.45 to 0.55 per cent., than tires today have, and the tires were smaller, the most common size of ingot weighing 1,060 lb. each. BRADLEY STOUGHTON, New York, N. Y.-This paper was specially requested by the Iron and Steel Committee, because that Committee thought so important an industry should have its history written by one who was familiar with it, and before he had forgotten, or all the rest of the world had forgotten, its early stages. Mr. Aertsen has said that it is not an exhaustive research. I think it would not be any different if it were an exhaustive research, because our library made a careful attempt to find some written light on the history of these tires, but very little was found.

Jan 4, 1917

By Dorsey Hager

DORSEY HAGER, Tulsa, Okla.-I have been asked why the Dexter region is dry. I would like to know myself. I drilled two dry wells on that same anticline which has production to, the east and west and south and north. That same anticline has seven domes that have been drilled and only three have proven productive out of the seven. In other words, you have one well-defined anticline with seven domes along its length, all mappable, all checked carefully, and only three of those seven have produced. Now why the others did not produce, I do not know. L. L. HUTCHISON, Tulsa, Okla.-There is no appreciable difference in the character or structure of the sands? DORSEY HAGER.-NO, I have never .been able to see any appreciable difference in the sands where we got production and Where we did not get it. I will say that the deepest wells we drilled, in the vicinity of Dexter, had no sands at the point where they got the production farther north. I. N. -KNAPP, Ardmore, Pa.-I first went to the Kansas-Oklahoma field in 1895 and occasionally thereafter until 1899, when I began drilling; for oil. I started close to wells that were producing gas and which, when drilling, lead made good oil showings in a sand above the gas. I thought these showings were good enough evidence of an oil pool for me without looking for any anticline and I made a paying development in what' I was afterward told by geologists was probably a synclinal trough. If I remember correctly Dr. Orton's report on the lola gas pool (about 1898) he distinctly said that he found no evidence of anticlinal structure and concluded from the records of a large number of wells that there, was a terraced structure of the productive gas sands, of which there were no surface indications.

Jan 4, 1917

By A. L. Field

WOOLSEY McA. JOHNSON, Hartford, Conn. (written discussion).¬When ;we regard the number of British thermal units running into the billions that-must be applied to metallurgical slags in the United States, we cannot but conclude that the physical chemistry of-slags is a very important subject when measured in dollars and cents. A further contemplation of the subject shows us that it has been hitherto treated in too purely a practical manner. It is needless to comment at length on the cost of these heat units and on the cost of fluxes to produce these metallurgical slags, for, it amounts to tens of millions of dollars annually. Accordingly, this research is of value to the country. But we must,all balance our results against our efforts. Therefore, while the speaker is unwilling to criticise unduly this meritorious research, lie does criticise it in the interest of the profession for the reason that it seems to him too highly theoretical. The article is much too, scientific to produce results at a minimum cost. Let us explain our meaning. It has been said that there are always two sides to a question. It may be further said that there are always three sides to a question, the two extremes and the middle ground. In any industrial research there are the highly theoretical side, the purely practical side, and the theoretico-practical side. To study a slag and be practical in the studying, there is something needed that represents in the laboratory (or in microcosm) what actually happens macrocosmically in the blast furnace. There is such a thing as the art of metallurgical research occupying the middle ground between theory and practice.

Jan 4, 1917

By Henry Howe

W. E. RUDER, Schenectady, N. Y.-In 1913 I presented a paper before this society on Grain Growth, and at that time it seemed to me that the only explanation for grain growth was that of critical strain. I do not think I published the photographs at the time, but I made some experiments on the effect of stretching sheets of metal. This allowed for fairly accurate determinations of the amount of cold deformation, At the time I worked-with silicon steel because one could see the change in grain growth with the naked eye. I stretched about 10-samples from 0.5 per cent. to 10 per cent., and, after heating to 1,050° C., I found that the maximum grain growth occurred at about 2 ½ per cent. cold deformation. This I designated "the critical strain" for maximum grain growth. About a year ago I talked with Prof. Jeffries, who explained to me his ideas of grain growth. It occurred to me that it would be a very easy thing to check the strain hypothesis against the strain and temperature hypothesis, if we took a certain number of these strips, strained exactly alike and heated to different temperatures; in that case the maximum grain growth ought to appear at a different percentage of deformation for each temperature. These experiments showed that there was, as Mr. Jeffries shows in his present paper, a decrease in germinative temperature with increased cold deformation. The samples were stretched from ½ to 8 per cent. and heated for 10 hr. in hydrogen. Samples were introduced into a furnace previously heated to temperature. A maximum grain growth was obtained at 5 per cent. deformation, when heated to 750° C.; at 2 ½ per cent. when heated to 800' C.; at 1 1/4 per cent., if heated at 950°C.; and at 5/8 per cent.. when heated at 1,100° C. This shows very clearly that the germinative temperature decreases with the increase in cold deformation. The growth was very much more marked, however, at the high temperature, i.e., the grain grew more rapidly and attained a much larger size than at lower temperature. In considering the photographs (Fig. A) those along the lateral edges should be ignored because.

Jan 4, 1917

By Luther B. Eames

J. V. N. DORR, New York, N. Y.-I have read Mr. Eames' excellent paper on this' subject with great interest, for besides being connected with the design and installation of the first modern countercurrent decantation plant, he was associated with me in the development of the thickener in the Black Hills some years earlier, and has now been operating the largest plant that has used this method of treatment. His, discussion, of the influence of different factors on the results obtained is quite thorough, but several features I think may not be apparent to the reader who has not studied the subject carefully. 1. Grade of Ore That Can Be Treated.-Mr. Eames has shown graphically that' the assay of all solutions increases directly as the grade of the ore treated. He has not emphasized, however, the fact that, as most operators prefer to keep the assay of pregnant solutions down below a certain figure in order to insure complete precipitation, an increase in ore value beyond a certain point means a proportional increase in solution precipitated and therefore not only an increase in the percentage of dissolved gold recovered, but an actual descrease in tailing loss. The importance of the influence of the percentage of moisture in the underflow on loss is made clear, and I. may add that unless it is quite evident that pulp can be safely settled to 50 per cent. solids, or more, it is usually advisable to use a continuous filter at the end of. a decantation plant to reduce losses in cyanide and gold. Dissolution in Thickeners.-The influence of a change of solution on silver dissolution has long been emphasized and most gold operators have. recognized the annoying way in which a gold ore after being agitated until nothing more can be dissolved will loosen up again when almost ready for the dump after the dissolved metal has been removed by decantation or filtration. Continuous decantation gives favorable conditions for this additional dissolution and a chance to recover most of what is thus dissolved. This is especially true if an extra tank is used in the series and barren solution added at the second tank from the end instead, of the first, as shown in Mr. Eames' Fig. 1. It can be calculated that the use of this tank will reduce the mechanical loss of cyanide by one-third and cut the gold loss as well; but the saving in gold or silver that may dissolve when the pulp is first diluted with weak solution may be as important.

Jan 4, 1917

By G. F. Comstock

H. M. BOYLSTON, Cambridge, Mass.-It might be asked, since this test is so simple, why it was not discovered before. It seems to me the explanation is that when we have used the sodium picrate solution, it has .generally been on a very, high-carbon or hypereutectoid steel; to detect . the presence of free cementite, and when we have looked for sulphides, it

Jan 4, 1917

By John H. Bell

R. B. T. KILIANI, New York, N. Y.-I wish to present some figures based upon actual observation extending over a few months time which seem to prove the author's conclusions. It is a comparison of two machines operating on the same ore, in the same plant, one taking the undersize of ½ -in. screen and the other taking the undersize of 8-mesh. Each of the machines was first operated as a pebble mill, with flint pebbles, in open circuit, then with metal pebbles in open circuit and, finally with metal pebbles in closed circuit. For the first case, the percentage of oversize on 48-mesh, Tyler screen, in the discharge, varied, in the mill taking ½ -in- feed, from 37.2 to 19.9 per cent. The second mill, taking the 8-mesh feed, had a variation in oversize on 48-mesh, from 36.8 per cent: to 0.5 per cent.; so it is seen there is considerable variation in these figures. I have computed the tons per kilowatt-day reduced through 48-mesh for each machine under each one of these conditions, giving 6 sets of figures. The first of these I called 1.0 and determined the ratio of the others to this.. In the snipe way, I figured the relative mechanical efficiency according to Kick's law, using' the figures given by Mr. Taggart in his paper, for ordinal numbers of the Tyler screens. I have also figured the efficiency in mesh-tons per horsepower according to Gates' method by plotting the screen analyses of feed and product and multiplying the area by a constant dependent on the scale used. The commercial efficiency of tons per kilowatt-day reduced through 48-mesh checks very closely with the efficiency by Rittinger's law, within 1 per cent. except in one case. By Kick's law, the efficiency checks fairly closely, within about 5 per cent., with the commercial efficiency of the mill grinding feed, but when we start to grind a finer, 8-mesh material, and especially grinding very fine; with a

Jan 4, 1917

By J. Spotts McDowell

J. W. RICHARDS, So. Bethlehem, Pa.-The paper is certainly an exceedingly, valuable one and it gives detailed information which should be utilized in the following way. There are probably twenty different circumstances or conditions under which silica bricks are used. Sometimes they are used under high pressure, at others under low pressure, at times for low temperatures and others for very high temperatures. If the methods of this paper are followed out, and if the precise mechanical and thermal properties are determined and can be reproduced, the industry can furnish the proper brick for any particular purpose. There is at present only an imperfect classification made as to properties and uses, but we need a "much more scientific classification of the uses to which the bricks are to be put and then should manufacture the bricks suited particularly for each of those purposes. There is one property which is not mentioned in the paper and which is of considerable importance, that is, the 'electrical conductivity. There may be other properties besides, which a good research laboratory can determine, and when we have listed all the various properties and noted the way in which they can be reproduced, the maker can then specify his exact requirements and the corresponding quality of brick can he selected or made to meet them. H. D. HIBBARD, Plainfield, N. J.-About a year ago I had some experience in another country, in melting steel, where silica bricks made in that country failed, but in a different way from those in America. Here, when the bricks get too hot, they are partly melted and string down

Jan 4, 1917

By E. M. Chance

HERBERT M. WILSON, Pittsburgh, Pa. (written discussion).-Permit me to endorse the author's conclusions and their form of presentation as ,being, in my judgment, the last word 'on the subject of lights for the illumination of coal mines. I also feel that the open-flame oil lamp has outlived its usefulness, and that it should go, in the interests not only of safety but of efficiency. Where an open-flame lamp can be used with safety in non-gaseous mines, the acetylene light adds materially to efficiency by its better illumination, and to safety for the numerous reasons given by Mr. Chance. The latter, however, lays chief stress on the value of the acetylene because of its non-fouling and non-obscuring effect on the atmosphere. Another important advantage over any other form of illumination is the clear, bright light projected at the point where the workman may look for danger. The better illumination materially safeguards the worker against obstacles over which he may stumble when traveling, and against dangers from falls of roof or of coal, weakness in timbering, and similar conditions. The acetylene lamp, where it may be used with safety, has advantages even over the present electric cap lamp, in that it gives a higher luminosity; and when the miner comes to learn its signals, as he will in time, just as he learns those given by the open-flame or the safety lamp, he will find that the acetylene lamp is a fair detector not only of methane but of carbon dioxide, as clearly shown by Mr. Chance. The only, serious objection, raised against the use of carbide lamps. has been recently in Pennsylvania, due to the belief of the State Mine Inspection Department that it endangered miners working on pillar work, or other places where carbon dioxide might accumulate, or where there is lack of sufficient ventilation, and because it was believed that the indications of the carbide lamp would not give the miner sufficient warning. On this point Mr. Chance has clearly shown the fallacies of the objections. I may add that for those unable to detect carbon dioxide with the acetylene lamp, the maximum of protection would be afforded by using an open oil lamp or a flame safety lamp in such places; or, because the miner might not watch his oil light, a better, protection still would be offered by a sufficient number of daily inspections of such working places by a fire boss or other official, with flame safety lamp.

Jan 4, 1917

By Frank Schrader

J. DANA SPERR, Jerome, Ariz. (communication to the Secretary*).¬Very little accurate information has been published about this district. Most of the geological data appearing in the technical press are based on "careful observations" made from an auto stage and a casual glance through the U. S. Geological Survey Bulletins, No. 340 of 1908 or No. 397 of 1909, both by F. C. Schrader. Mr. Schrader's report is still the best publication on the district. A really careful study of this report will uncover only a very few statements which have since proven questionable. This is a remarkable record when it is considered that only a short time was spent by Mr. Schrader in the field and that there was very little development work done at that time. The mining world and especially Mohave County, Ariz., will feel a sense of gratitude to Mr. Schrader for revising his early report. on this

Jan 3, 1917

Herbert C. Hoover, who became a member of this Institute in 1896 and who is now one of its Vice-Presidents, is the man who in 1914 extended a helping hand to Americans stranded in Europe at the outbreak of the war, and who made it possible for many such travelers to return safely to their homes. When his countrymen no longer needed his services, he turned to the Belgians, whose need of food had been presented to him. Engineers have been among his assistants from the first, and it is because we believe that members of his own profession will still be particularly interested in his work that we thus mention it in the Bulletin. A Minute adopted by the Board of Directors of the Institute, in which the Belgian Kiddies, Ltd., is recommended to the consideration of the members, immediately follows the Proceedings of the Meeting of the Board of Directors. With the thought that members of the Institute may be glad to read Mr. Hoover's own words in regard to his work, we print in full the speech

Jan 3, 1917

By A. L. Field

A. W. FAHRENWALD, Socorro, 'N. M. (communication to the Secretary*).-When asked to discuss Mr. Feild's paper, I felt most highly complimented to have the privilege of commenting on such a worthy and needed piece of apparatus. In consideration of the importance of the viscosity of blast-furnace slags and the relation existing between the' melting point of a slag and its viscosity, the introduction of this apparatus should be a welcome means or assistant in the study of the physical properties of a slag. Up to the present time, it is A fact that this side of the practical working of the blast furnace has been sadly neglected by those investigating slags. It is easily seen that the fluidity of a slag is of as great importance as its melting point. It is not necessarily true that a slag having a low melting point will have a correspondingly low viscosity or be highly fluid. For example, a slag having a melting point of 1,100° C. may have to be superheated to, say,1,300° C., in order to have as high a fluidity as another slag whose melting point is, say, 1,250° C. The latter in this case would be the more economical. This point has been brought out very nicely by Mr. Feild. Before discussing this paper further, I think it will be well to outline some of the points, a discussion of which may be in order:

Jan 3, 1917

By R. J. Wysor

CHARLES H. RICH, Conshohocken, Pa. (communication to the Secretary*).-Mr. Wysor has certainly covered his subject in the most thorough and able manner and his paper will no doubt result in enlarged effort toward the conservation of this important byproduct. Not all furnace burdens are as rich in alkalies as those noted by Mr. Wysor. In our own experience we have never gone into any extended examination of the materials entering the furnace burdens, but have made a number of determinations of the water-soluble alkalies of our flue and boiler dust and found maximum of about 4 1/2 per cent. K20-too small for profitable reclamation. We have, however, frequently encountered the smoky gas described by Mr. Wysor. Such gas carries heavy fume, and buds with a fitful flame difficult to maintain. So pronounced was the inhibitory effect of the fume that, in extreme cases, the flame of a lighted match was extinguished by the current of gas and it was found impossible to conduct calorimeter tests without preliminary washing of the gas. When the gas was led through a washer filled with distilled water and pieces of coke, the fume was absorbed and the gas burned without difficulty. Careful analyses conducted on the water solution from the washer showed cyanides in increasing amounts in proportion to the difficulty experienced in burning the gas. We, note Mr. Wysor's statement that he has never found evidence of cyanides in their gas, ascribing the difficulty of burning such gas to the presence of chlorides. Our determinations were conducted in such manner as to preclude possibility of interference by chlorine.

Jan 3, 1917

By Henry Fay

LAWRENCE ADDICKS, New York, N. Y., (communication to the Secretary *).-There are two points regarding gun erosion on which I want to say a few words: The first is about the analogy to hardening of wire by drawing and the second the possible role played by thermal conductivity of the metal. The ductile metals do not necessarily become brittle when cold-worked as it is possible to draw copper from 3. in. in diameter soft rod down to the finest hair wire without annealing. This results, as stated in the paper, informing a hardened core with a very hard skin. The electrical conductivity is depressed some 3 per cent. and the tensile strength nearly tripled. A soft copper wire 0.08 in. in diameter and 6 in. long may be twisted 150 or more turns before the wire will snap under torsion. A hard-drawn wire will break after perhaps a dozen twists, the skin breaking down at one spot. Just wiping the wire with a cloth clamp with dilute nitric acid has a remarkable effect in increasing the number of twists without appreciably lowering the tensile strength, showing the skin to be very thin. On the other hand, pickling the rod, from which the wire is to be drawn, in dilute nitric acid also greatly increases the number of twists which can be applied to the resulting wire. This indicates that the copper oxide scale produced when the wire bar is rolled hot is more or less rolled into the rod and may have much to do with the skin effect. We also know that if the conditions of drawing are not correct, the heat of deformation in the die may produce quite an annealing effect. The application of this analogy to what occurs in a gun to produce the effects noted offers some difficulty. The second point is that as the temperature of the surface of the gun bore has undoubtedly a great deal to do with the amount of erosion, one natural remedy would be to conduct the heat away fast enough to keep this temperature within desired limits. This brings up the question of the thermal conductivity of the metal of which the gun is made. We know that the conductivity of pure metals is greatly altered by alloying and that the alloy is usually, though not always, lower in conductivity than the metal before alloying. This is interesting when it is considered that the high-nickel and manganese-steel alloys show greater erosion as stated. Would it not be instructive to study the question from the point of view of heat conducted away from the eroded surface?

Jan 3, 1917

By F. H. Willcox

IN Bessemer-steel practice, air is blow, through a bath of iron, or projected strongly upon its surface to burn out silicon, manganese, and carbon. Toward the end of the blow, when the iron is not protected. from oxidation by these elements and the excess of air becomes great, there is oxidation of the iron. In open-hearth practice, the same difficulty is experienced with dissolved gas and oxides in the product, though not to as great or severe a degree as in the Bessemer process because the oxidizing conditions grow less severe as the end of the heat is approached, and if the bath is allowed to boil for a time it undoubtedly frees itself from a large part of the gas and oxides which have been absorbed in the earlier part of the process. Basic open-hearth steel is usually assumed to contain a larger proportion of oxides than acid open-hearth steel, but it may be said that all steel, Bessemer and open-hearth, contains more or less oxide of iron dissolved in the fluid metal at the end of the "blow" or "heat." That certain metals are solvents for their respective oxides has been shown, in the case of copper, by Heyn, and, in the case of iron, by Law. It is indicated that the solubility of iron oxide in iron increases with the purity and temperature of the metal. This confirms what is observed and known by operating men, and these observations may be summarized as follows: 1. Cast irons is rarely subject to oxidation, as is logical from its composition. 2. Normal steel, unless deoxidizers are added, contains blow holes. 3. Steel known to be oxidized is full of blow holes. 4. The addition of deoxidizers prevents, to a greater or less degree, the formation of blow holes in normal steel. With these observations in mind, it is logical to deduce that the cause of blowholes lies in part in the presence of dissolved oxide of. iron in the

Jan 2, 1917

By C. Edwin Nighman

THE following is a description of the methods used in rescuing men and extinguishing the underground fire at the Pennsylvania mine, Butte, Mont. This fire, which cost the lives of 21 men, began about 9 p.m., Feb. 14, 1916, at or near a ventilating fan on the 1,200 air-shaft station. This shaft at that time was downcast, while the main hoisting shaft was upcast. Owing to the proximity of the fire to the air shaft, the air in the latter soon became heated, and as the fan on the level was not running¬the power having been cut off shortly after the outbreak' of the fire-the aim' shaft became upcast to the 300 level. At this point a blanket of cold air from the surface caused the smoke and gases to he drawn in on that level and carried down again through the workings to the 1,200. A short time after the discovery of the fire, water was turned down the air shaft through a series of pipes around the collar of the shaft, which caused the smoke to recede, below the 300, so that within 2 hr. it was possible to search that level for the missing men. From the above it will be apparent why the air shaft was upcast instead of downcast as under normal conditions, and why men were suffocated at considerable distances from the seat of the fire. The smoke and gases that came up the main hoisting shaft did not diffuse through the workings to any extent. There are doors on all levels in the connections to the main hoisting and air shafts, but-in the confusion and running around many of these doors were left open, and this undoubtedly caused the smoke and gases to spread more rapidly than they would otherwise have done. It was necessary for most of the men on the various levels to pass close to the air shaft in going to the hoisting shaft, and when they encountered the smoke and gases in that vicinity a number turned hack and climbed down with the direction of the air currents and were then suffocated, while all those who passed through the relatively short pall of smoke to the main shaft were saved.

Jan 2, 1917

By A. Patton

Introduction THE use of roll scale in the Bessemer process dates back, to the "best of our knowledge, at least 20 years. It was first used by the Ohio Steel Co.; Youngstown, Ohio (now the Ohio Works of the Carnegie Steel Co.) under the direction of Sam, MacDonald, Superintendent of the Bessemer Department at these works. Two 10-ton vessels and one blowing engine capable of blowing one heat at a time were employed. The object of using the scale was to -shorten the length of the blow; or in other words, to increase the production with the same equipment. Various means were tried out for introducing the roll scale into the bath of molten iron: It was shoveled into the vessel before the heat was charged, so that the metal would flow over the scale; it was shoveled into the bath after the vessel was turned up; it Was dumped into the empty iron ladle by the wheelbarrow-load, and at times wars dumped on top of the molten metal in the iron ladle. But the practice of introducing the scale into the iron ladle had to be abandoned on account of danger from explosions and of skulling the -ladles. It was soon learned that the proper place to charge the scale was in the empty vessel, so that when the molten iron was poured into the vessel it flowed over the scale, causing a considerable reaction to take place before the heat was turned up. Eventually, cylindrical chutes similar to those now in use were installed. Into these chutes the scale is dumped and carried into the empty vessel. Before this convenient means of introducing the scale was adopted, the Ohio Works had satisfactorily demonstrated that roll scale would increase production, by blowing 107 heats in one 12-hr. turn (1,087 tons) with one blowing engine, blowing one heat at a time; whereas, prior to the use of scale, the best practice at these works was about 80 heats under the same conditions.

Jan 2, 1917

CHICAGO SECTION CHARLES H. MACDOWELL, Chairman, Luther V. DICE, Vice-Chairman, HENRY WT. NICHOLS,. Secretary-Treasurer, 164.5 E. 68 St., Chicago; Ill. ALEXANDER K. HAMILTON-, HENRY P. HOWLAND, GEORGE P. HULST, FREDERICK 1. SNYDER. There were 32 members present at the dinner of the Chicago Section which was held at the Chicago Engineers' Club on Friday Evening, December 22. At the meeting after the dinner, the Chairman called attention to the work of Mr. Hoover in Belgium and spoke briefly of the assistance which' could be given him through the Belgian Kiddies, Ltd. Mr. Alonzo Kinyon read a paper on "Burring Powdered Coal" which so interested the members that many of them participated in the long discussion which followed. Prof. Harry B. Pulsifier then described the metallurgical plants about Chicago. He mentioned briefly the equipment and interesting features of 30 metallurgical plants of importance and stated that there were also 200 foundries in the district. He said that when number, size, quality and diversity of the plants are considered, the Chicago District is justified in calling itself the greatest metallurgical center on earth. The paper was followed by a brief discussion in Which attention was called to some smaller and incipient plants of an interesting character. HENRY T. NICHOLS, Secretary.

Jan 2, 1917

By Richard Moldenke

ONE of the little-known characteristics of cast' iron, which neverthe-less has an important bearing on results where accuracy in machining-is essential, is the ability of this material to ease up internal strains when. .allowed to remain quiescent for a more or less extended period of time. At seems as if the molecules in such a casting, by virtue of their "mobility,? can adjust their relative positions to an extent sufficient to overcome some of the existing stresses. The following instance will perhaps give a fair idea of the condition a casting may he in when just shaken out of the sand. A very large sheave-wheel, after shaking out, was taken' outdoors to be, cleaned and made ready for turning up. It was leaned against the side of the building, but before much could be done an arm tore apart with a loud report. Investigation showed that the sun had been shining on the upper rim, this adding a slight strain to those already existing within the arm and thus overbalancing the strength of the metal in tension. Had this sheave been kept under cover for a while, or at least until machined, the-strains., would have eased off sufficiently to allow the sun to look upon it without disaster. It will not be necessary to multiply examples. Every engineer knows the danger of water-hammer in pipe lines, particularly if the latter are of cast iron. Every mechanic knows, or should know, that it is not good to strike a fitting that is under steam pressure. It will be necessary to say a few words on the "internal- strains" in castings-the so-called "casting strains" we hear so much about. We all know that to get a casting reasonably true to the dimensions wanted requires a slightly larger pattern. The usual allowance for gray iron is 1/8 in. to the foot (1 cm. per meter) and ¼ in. to the foot (2 cm. per meter) for white iron (all dimensions). This reduction in length, breadth and thickness in a casting is erroneously called "shrinkage." It should be called "contraction," as for practical purposes. it is simply the difference .in dimensions of the casting red-hot and cold.

Jan 2, 1917