STUDIES OF BLAST FURNACE PHENOMENA. STUDIES OF BLAST FURNACE PHENOMENA. BY M. L. GRUNER, PRESIDENT OF THE GENERAL COUNCIL OF MINES OF FRANCE, AND LATELY PROFESSOR OF METALLURGY AT THE ECOLE DES MINES. TRANSLATED, WITH THE AUTHOR'S SANCTION, WITH AN APPENDIX, BY L. D. B. GORDON, F.R.S.E., F.G.S., EMERITUS REGIUS PROFESSOR OF CIVIL ENGINEERING AND MECHANICS IN THE UNIVERSITY OF GLASGOW, FORMERLY A STUDENT OF THE ROYAL SCHOOL OF MINES, OF FREIBERG, IN SAXONY; HONORARY MEMBER OF THE INSTITUTION OF ENGINEERS AND SHIPBUILDERS IN SCOTLAND; MEMBER OF THE IRON AND STEEL INSTITUTE. PHILADELPHIA: HENRY CAREY BAIRD, INDUSTRIAL PUBLISHER, 406 WALNUT STREET. 1874. PHILADELPHIA: OOLLINS, PRINTER, 705 Jayne Street. CONTENTS. PAGE LETTER TO ISAAC LOWTHIAN BELL, ESQ... X TRANSLATOR'S PREFACE... ii SECTION I. Recent Modifications in the R6gime of Blast Furnaces.. 17 SECTION II. Successive Enlargements of Blast Furnaces.18 SECTION III. Principal Reactions in Blast Furnaces.24 SECTION IV. Quantities of Caloric absorbed and given off in Blast Furnaces.. 26 SECTION V. The Economical Working of the Furnaces varies with the ratio of cO, in the Gases. 29 CO SECTION VI. The ratio co0~ is the Measure or Index of the Economical Working of Blast Furnaces CO of Blast Furnaces. 33 Vi CONTENTS. SECTION VII. PAGE Weight and Composition of the Escaping Gases-Construction of Analytical Formulas of Calculation.34 SECTION VIII. Agreement of the Formulas with the Complete Analysis... 38 SECTION IX. A Method of taking Specimens, securing a Mean of all the Gases during several hours.42 SECTION X. Determination of the Caloric consumed in Blast Furnaces... 46 SECTION XI. Caloric absorbed by the reduction of the Ores and the fusion of the Pig-Iron.47 SECTION XII. Caloric absorbed by the fusion of the Slag, the decomposition of the Limestone, etc.. 52 SECTION XIII. Sensible Heat carried off by the Gases.54 SECTION XIV. Caloric lost by Radiation from the Walls of Furnace, etc... 55 SECTION XV. Determination of the Caloric received by a Blast Furnace, solely derived from transformation of Carbon into a Mixture of CO2 and CO...........56 CONTENTS. vii SECTION XVI. PAGE First Example-Clarence Furnace, 1853-gives 0'40 of the Calorific Power of Coke consumed....... 59 SECTION XVII. Secon~d Example —Clarence, 1866-gives 0-48 of the Calorific Power of Coke consumed......... 63 SECTION XVIII. Third Example-Ormesby Furnace, 1867-gives 0'44 of the Calorific Power of Coke consumed.67 SECTION XIX. Fourth Example-Consett Furnace-gives 0'45 of Calorific power of Coke...... 70 SECTION XX. Fifth Example-Consett Furnace-gives 0'47 of the Calorific Power of Coke........ 73 SECTION XXI. Consequences derived from the preceding Examples-Synoptical Table of Results..... 77 SECTION XXII. Influence of Extra-Slow Working...... 86 SECTION XXIII. Influence of great Height and Capacity.. 88 SECTION XXIV. Beyond a certain height the Temperature of the escaping Gases does not diminish by reason of the dissociation of the Oxide of Carbon 93 Viii CONTENTS. SECTION XXV. PAGE Influence of Highly-heated Blast...... 101 SECTION XXVI. Conclusions. 116 SECTION XXVII. Application of the New Method of Analysis to a French Blast Furnace-gives 0-48 of Calorific effect of Coke consumed.. 118 SECTION XXVIII. Another Example of French Blast Furnaces.128 CONTENTS. ix APPENDIX. PAGE NOTE I. On taking Specimens of the Escaping Gases... 135 NOTE II. To explain what is meant by "Strengfliissige Erzen," "Minerais refractaire." Plattner's Experiments on the Temperature of Formation of Slags. 136 NOTE III. On Ebelmen's assertion that it takes twice as much Coke as Charcoal to smelt the same quantity and quality of Pig-Iron. 138 NOTE IV. Charcoal decomposes CO2 more rapidly than hard or soft Coke does.139 NOTE V. A Brief History of the Theory of the Blast Furnace, and of most recent practical results.140 Lampadius-1837-38.140 Karsten-1839.......... 141 Bunsen first analyzed Blast-Furnace Gases, and drew consequences therefrom-1838.. 143 Ebelmen followed in the same course-1840-42... 144 State of Calorimetric determination of the Caloric of combustion in 1839..144 Before analyses of Gases were made, viz., 1811, they were variously applied in France.145 Patent of Mr. Palmer Budd-1860. 145 Percy's "Metallurgy of Iron and Steel," published 1863-64. 147 Schinz's Work, published 1868, was the first which took the Calorific Phenomena of the Blast Furnace into consideration 148 Schinz's Experiments on Reduction. 148 ;X CONTENTS. PAGE Lowthian Bell's Studies of Blast Furnace Phenomena began to be published in 1869.152 Experiments on Reduction by Furnace Gases directly applied. 154 On the presence of Alkaline Cyanides 157 On Dissociation of CO...... 159 On the Behavior of Limestone...... 164 On Influence of Superheated Blast...... 168 NOTE VI. Useful Tables and Memoranda for Calculations of Blast Furnace Phenomena. 175 INDEX......... 181 To ISAAC LOWTHIAN BELL, ESQ., President of the Iron and Steel Institute. MY DEAR BELL, In the hope of being useful.to members of the Iron and Steel Institute, and others who do not read technical literature in foreign languages, this translation of M. Gruner's "i tudes sur les Hauts-Fourneaux" was undertaken. You have allowed me to dedicate the translation to you. No one having any knowledge of the subject will ask my reason for doing so. M. Gruner has methodically digested and arranged several important sections of your experiments and observations, and has thus rendered the results you have published more readily available to many who desire to inform themselves of the progress made in the application of exact science to blast furnace practice, and who lack the habits of study necessary for the full appreciation of your original work. The series of memoirs you have published in the Journal of the Iron and Steel Institute, on the chemical phenomena of iron-smelting-your careful diligence in the experimental verification of your observations in working furnaces, and your philosophical views in combining and reasoning upon them-have identified your name with the recent progress towards an exact theory of that wonderfully perfect apparatus, the Blast Furnace. You for the first time connected the Chemical and Xii LETTER. Calorific phenomena of the Blast Furnace together with such precision as permits us to calculate, with the certainty of a near approximation to the truth, the technical useful effect of any furnace, and the economical effect of furnaces working in any district for which the proportions of fuel, ores, and fluxes, and the temperature of the blast are known. The results of your observations, and the numerous facts elicited from many practical men in the "discussions" at the meetings of the Iron and Steel Institute, are indeed the groundwork of M. Gruner's "Studies," in which he establishes Analytical Formulas by which all the necessary calculations can be readily worked. The happy remembrances of thirty-three years' social intercourse and sympathy in the study of science applied to the arts, is an independent reason for my offering you this tribute of my friendship and esteem. Believe me to be, Yours sincerely, LEWIS D. B. GORDON. TOTTERIDGE, August, 1873.. TRANSLATOR'S PREFACE. THE Studies of Blast Furnace Phenomena by M. Gruner are not written in a style that "those who run may read;" but whoever will take the pains to read them will find his reward in a more exact appreciation of how the recent investigations of Mr. Bell and others into the chemical and calorific phenomena of the blast furnace may be practically applied to questions of blast furnace economy. For the last three years the question of the mindimum cost, theoretically and practically, of producing a ton of pig-iron has chiefly occupied the attention of the meetings of " the Iron and Steel Institute," and has even been "discussed" at meetings of the Institutions of Civil and Mechanical Engineers. There is evidently no general answer to the question. Each particular case must be investigated for itself; and M. Gruner has so far generalized the results of experiment and observation hitherto recorded as to give formulas by which the chemical and physical elements of the question may be answered approximately a priori (see p. 122 et seq.) This answer may be made with sufficient accuracy for practical purposes by ascertaining merely the proportion of carbonic oxide to carbonic acid present in the xiv TRANSLATOR S PREFACE. escaping gases of any furnace of which we know the elements of its charges. The main point of novelty in the Studies, and what gives them their chief interest, is the precision given to this doctrine, first distinctly taught by Mr. Bell, that the ratio of CO in the escaping gases is the index of the working of thefurnaces. The determination of an analytic process of calculation in place of a synthetic is of value for direct investigation of any case of blast furnace working that may present itself. Still, the other question debated, be it borne in mind, is the economy of fuel in furnaces, whether charged into the furnace and consumed there, or supplied from without as caloric in the heated blast. Again, it is only when furnaces are working with the same, or nearly the same, charges of ore, flux, and fuel, i. e., same quality of raw materials, and yielding the same quality of iron, that we can get comparative results of a reliable nature. Furnaces may be working in one district as well as in another, although using very different quantities of ore and fuel, and yielding very different quantities of iron, and showing very different profit and loss accounts. Pig-iron making, like other manufactures, must be looked at both from the purely technical and the economical point of view. There is a technical maximum of useful effect and an economical maximum of useful effect. The technical useful effect would be so much the greater as the yield of pig-iron from a given weight of carbon and ores of the poorer qualities is greater, TRANSLATORSS PREFACE. sv whereas the economical effect often involves other considerations, such as the maximum production of iron of a certain quality regardless of the maximum technical effect. In most cases, the iron-master is chiefly interested in the technical effect. There is however one factor of technical effect, viz., that of the superheated blast, which has for the last three years excited the liveliest controversy. The section 25 of the "Studies" treats of this question on the basis of the experience recorded by Mr. Bell and others in the Transactions of the Iron and Steel Institute, and on the assumption that the combustiblefor heating the blast is the gases of the furnace itself. M. Gruner's examination of the question is, like that of Mr. Bell, full of instructive applications of the actual theory of the blast furnace. The conmplete technical answer awaits the result of experience of the cost of superheating the blast. To the question, whether there is advantage in heating the blast to 800~, 900~, or 1000~, the theoretical answer is undoubtedly Yes. For each rise in temperature of the blast there is increased economy, abstraction being made, of course, of the cost of maintaining and firing stovesfor heating the blast. At the same time, this economy decreases rapidly with the rise in temperature. The economy arising from each accession of 100~ to temperature of blast is much less from 800~ upwards than from 5000 to 7000, and still less than between 400 and 500~, and thus in practice it is useless to exceed 7000 to 8000. Not having been able to collect sufficient data as to the cost of making and maintaining the stoves for superheating the blast, it Xvi TRANSLATOR'S PREFACE. is impossible for me to add to the weight of this opinion of M. Gruner, excepting to say that, after examination of all the facts hitherto published, superheated blast beyond the limits safely reached by the cast-iron stoves is useless; and if, as seems to be the case, it be thought necessary to erect generators of gas to heat brick stoves, that system is certainly wasteful, and a retrograde step in blast-furnace engineering. This subject is again alluded to in Note V., Appendix. Some apology is due for writing so much as an Appendix. The truth is, that I examined each subject and factor mentioned in the original text for myself, and conceived it might be useful to others to record my notes for their use. LEWIS D. B. GORDON. TOTTERIDGE, September, 1873. STUDIES OF BLAST FURNACES. g 1. Recent modifications in the regime of blast furnaces.For several years past the minds of metallurgists have been much preoccupied by two important modifications made in old Blast furnace practice. The furnaces have been increased in height and in diameter, and the blast is spontaneously heated to a red heat, in England especially, by means of large stoves of fire-brick, prepared by Messrs. Cowper-Siemens, and Mr. Whitwell. Successive transformations in these two directions have resulted in what is deemed exaggeration by metallurgists, such as Mr. Lowthian Bell, whilst there are others who consider there is no limit save practical possibility. This divergence of opinions has been made known by the publications of the Iron and Steel Institute-an association frequented by Bessemer, Bell, Menelaus, Williams, Snelus, Parry, Siemens, Cochrane, and others well known as leading men in the iron industry of Britain. The question is one well worthy of careful examination and study in reference to the chemical and calorific reactions which come into play in these enormous apparatus. I shall, for this purpose, make use of the series of highly interesting memoirs which Mr. Lowthian Bell has published in the Journal of the Iron and 18 STUDIES OF BLAST FURNACES. Steel Institute,* and compare them with my own personal researches on the same subject, some of them given, for many years, in my course of lectures at the Pcole des Mines of Paris, and others recently published in the Recueil des savants etrangers, and in the Annales de physique et de chimie.t ~ 2. Successive enlargements of blast furnaces. —Blast furnaces, working with charcoal as fuel, are seldom more than 30 to 35 feet high, nor have they more than 800 to 1200 cubic feet capacity. In Austria, in Russia, and in Sweden, where circumstances admit of a great accumulation of fuel, the height is carried to 45 feet, and the cubic contents to 1800 to 2200 feet. In -coal districts the furnaces have been, from the beginning, made larger: and yet the ordinary furnaces of Staffordshire have not more than 2200 to 2500 cubic feet capacity, with a height of 38 to 42 feet; and even the largest do not exceed 3500 to 5000 cubic feet. In 1830, the capacity was not more than 2000 cubic feet as an average, and in Wales 2200 to 2500 cubic feet. In 1860, however, M. Lan and I found that there was a decided tendency to enlargement of the furnaces. In Scotland there were furnaces of 3000 cubic feet, and even 7000 cubic feet; and in Wales the furnaces were of 3000 and up to 5000, with some few as large as 7000 and 7750. These successive enlargements were made with the special object of increasing production, and we were convinced that, in fact, the yield had increased in proportion to the internal capacity. In the enlarged as in the smaller furnaces in England, the yield was, on the average, a ton of Nos. 1 and 2 iron for 7 to * Published in one volume complete, with Index, by Messrs. Routledge, in 1872. f Seavants etrangers, t. xxii.; Annales, etc., Mai 1872. STUDIES OF BLAST FURNACES. 19 8 cubic metres (245 to 280 cubic feet) capacity, a ton of forge iron (gray) Nos. 3 and 4 for 210 to 245 cubic feet, and a ton of mottled forge pig for 175 to 210 cubic feet capacity. By comparing together a great many Continental furnaces, I had previously arrived at the same results. In my lectures these figures were given as results to be used in determining the dimensions of blast furnaces. In 1851, the first blast furnace was erected in Cleveland, by Messrs. Bolckow & Vaughan, who built it 42 feet high, and of 4500 cubic feet capacity. In 1853, Messrs. Bell Brothers founded the Clarence Works, and erected several furnaces 48 feet high, and of 6200 cubic feet capacity. From 1853 to 1860, a great many furnaces were erected in this district, but none of them were carried to a greater height than 58 feet, with a capacity of 7000 cubic feet, and the greater number were about 50 feet high, with 5200 to 6000 cubic feet capacity. On the other hand, beginning from 1861, there took place a prodigious enlargement of the furnaces, of which we may give the following examples:In 1861, Messrs. Whitwell & Co. built three furnaces at Thornaby 60 feet high, and 13,000 cubic feet capacity. In 1862, Messrs. iBolckow & Vaughan carried the height to 75 feet, and the capacity to 12,000 cubic feet. In 1864, Mr. Samuelson built his first furnace, at Newport, 68 feet high and 15,300 cubic feet capacity; and Mr. Thomas Vaughan carried the height to 78 feet, and the capacity to 15,750. In 1866, Messrs. Bolckow & Vaughan adopted the lofty type of 96 feet, with only 15,000 cubic feet capacity; and 20 STUDIES OF BLAST FURNACES. Messrs. IHopkins, Gilkes & Co., at Tees-side, gave 76 feet height, and 20,000 cubic feet capacity. In 1867, the furnaces at Norton were made 78 feet high, and 26,000 cubic feet. In 1868, Messrs. Bolckow & Vaughan enlarged their two furnaces of 1866, the one to 26,000 cubic feet, the other to 29,000 cubic feet capacity, the original height being retained — viz., 96 feet. In 1870, Mr. Cochrane erected a monster furnace at Ormesby, 92 feet high, and 41,000 cubic feet, and at Ferryhill, westward of Middlesborough, with a greater height they combined a smaller capacity-106 feet high, 33,000 cubic feet; and lastly, in 1871, Mr. Cochrane built a furnace 92 feet high, and 42,500 cubic feet capacity. The internal section of the greater number of these furnaces is given in the plate, copied from the historical account of the gradual development of the blast furnaces in Cleveland, by Mr. J. Gjers.* We see by these that the form is very various-lofty furnaces almost cylindrical alongside of barrels very stumpy, enlarged at the belly, and much contracted at the top. These forms, as well as the height, the total capacity, the mode of charging, etc., have, as we all know, a certain influence in the working of the furnaces. The yield and consumption of raw material vary with these elements. Unfortunately, the short notice of M. Gjers does not give any details on this subject, not even an indication of the maximum yield; but this incompleteness I have, in p)art at least, been able to supplement by data given in the Memoirs of Mr. Bell, and the reports of the discussions which * Journal of the Iron and Steel Institute, Nov. 1871. STUDIES OF BLAST FURNACES. 21 these Memoirs gave rise to at the meetings of the Iron and Steel Institute. What strikes, us immediately is, that by common consent it is allowed that the yield of these big furnaces does not increase in the proportion of their capacity. Thus, at Clarence Works, Mr. Bell's own works, we find, for four types of very different dimensions from each other, yielding forge iron Nos. 3 and 4, the yields as follows: — _ A Old Furnace High Furnace High Furnace High Furnace Elements of the furnaces. of 1853. of 1866. of 1865. of 1870. Total capacity. 6000 c. ft. 11,500 c. ft. 15,800 c. ft. 27,000 c. ft. Height.. 48 ft. 80 ft. 80 ft. 80 ft. Production in 24 hours.' 30 tons. 38-6 tons. 50 tons. 60 tons. Consumption of coke per ton iron........ 29 cwt. 22] cwt. 221 cwt. 22] cwt. Internal capacity per ton iron yielded in 24 hours... 190 c. ft. 300 c. ft. 330 c. ft. 380 c. ft. On the other hand, the numerous furnaces of Messrs. Bolckow & Vaughan and those of Ferryhill, in which the same ores and the same coke are used as at Clarence, the blast being heated to the same temperature of 4000 C. to 450~ C., and the pig being also Nos. 3 and 4, gave the following results:Blast Furnaces of Messrs. Bolckow & Vaughan. Old Furnace New Furnace Elements of the Furnaces. at at Ferryhill. Ferryhill. Built, 1865. Built, 1868. Total capacity..... 15,000 c. ft. 25,800 c. ft. 17,000 c. ft. 32,000 c. ft. Height. 95 ft. 95 ft. 80 ft. 80 ft. Yield in 24 hours. 46 tons. 52 tons. " 50 tons. 78 tons. Consumption of coke per ton of pig. 22 cwt. 221 cwt. 221 cwt. 20* cwt. Internal capacity per ton yield in 24 hours... 320 c. ft. 490 c. ft. 315 c. ft. 420 c. ft. * This amount is uncertain. 22 STUDIES OF BLAST FURNACES. Lastly, by comparing the three successive types put up by Mr. Samuelson, at Newport, we again found the same figuresc. ft. c. ft. An old furnace of. 5000 yields 23 tons in 24 hours = 218 p. ton. Another furnace, 1864, 15,800 "' 45 " 342 " And the last furnace, 30,300 " 70 " 430 " Mr. Bell, in the discussions of the Iron and Steel Institute in 1871, affirms, with perfect reason, that he " never found that a furnace of 25,000 cubic feet did twice the work as well as one of half the size." In fact, we know that in the old-furnaces of 5000 cubic feet to 7000 cubic feet capacity, the mean capacity is 210 cubic feet per ton of Nos. 3 and 4 pig, whereas in the more modern furnaces of 10,000 cubic feet to 15,000 cubic feet, we find from 280 to 320 cubic feet capacity per ton of yield, and in the most recent furnaces of 25,000 cubic feet, the capacity per ton of yield is 420 cubic feet to 490 cubic feet. In other words, the descent of the charges requires 60 to 70 hours in the large furnaces, and only 20 to 40 hours in the small ones. This extreme slowness in the descent of the charges may, in a certain point of view, have advantages. Variations in the raw material are less sensibly felt in the large furnaces. It may also happen that reduction goes on under better conditions-that the ore should arrive in the zone of fusion better prepared. But is there no limit to this successive development of the blast furnace? May not the juste milieu corresponding to a maximum of economy be overstepped? If the work goes on very slowly, is not the carbonic acid (C02), arising from the reduction of the ores, exposed to be converted into carbonic oxide (CO) by contact with incandes STUDIES OF BLAST FURNACES. 23 cent carbon, in proportions increasing as the descent of the charges is slow? In short, is the consumption necessarily so much the less as their dimensions are large, and the descent of the charges slow? The figures above tabulated answer this question to a certain extent. Previously to 1860, the blast furnaces in Cleveland consumed 1'5 to 1'7 tons of coke for one ton of pig -gray forge-yielded, or, at the very least, 1'45 tons = 29 cwt., according to the statements of Mr. Bell. At present, the consumption in the enlarged furnaces is reduced to 14125 = 221 cwt., the blast being heated to 400 to 500 degrees Centigrade: but it is quite certain that there is no difference in the consumption of the furnaces of 10,000, 16,000, and 28,000 cubic feet capacity, or even beyond these monstrous dimensions. If, therefore, beyond a certain limit, the large dimensions produce neither increased yield nor economy of fuel, it does not look very rational to go on increasing the capital for establishing furnaces with these vast dimensions.*' This is what has at last occurred to our neighbors on the other (English) side of the Channel. A reaction has taken place in England, at all events in those districts in which the fuel and the ores are liable to crush and compress under their own weight. Thus at Askam-in-Furness, the height has been reduced from 75 feet to 61; at Consett, the furnaces have been reduced from 70 feet to 55; at Workington and at Barrow, situated like Askam in the district of rich haematites of Cumberland, the body of the furnaces has, in like manner, been reduced in height-at Workington, from 70 * See note on estimate of cost, Appendix. 24 STUDIES OF BLAST FURNACES. feet to 55, and at Barrow, from 75 to 61;* and lastly, at Creusot, a blast furnace which had been raised to 88 feet has likewise been decapitated. These examples are sufficient to show that a certain height is accompanied by proved inconveniences; but if we desire to appreciate at its true value the influence of these exaggerative dimensions, we must, in the first place, endeavor to form exact notions of the chemical and calorific reactions upon which the working of the blast furnace is based. ~ 3. Principal reactions in blast furnaces.-In every furnace of this type, there are two contrary currents in motion, and -reacting the one upon the other-a gaseous current ascending, the temperature of which is at first very high, and decreases gradually till it quits the furnace at the tunnel-head or top; and a solid descending current, composed of the ores, the fluxes, and the fuel, the temperature of which goes on increasing always under the action of the gaseous current in the opposite direction. Of these two currents the one is slow, the other very rapid. The solid materials of the charges descend rarely with a greater speed than 20 inches per hour, whilst the gases pass upwards with a velocity of 20_ inches per second. Further, the mass of air blown into the furnace is generally greater than that of the solid charges by the tunnel-head in the same time; and the weight of gases going off from the furnace is often more than double that of the melted substances (pig iron and slag) flowing out by the "tap" and slag discharge. The air, blown into the furnace at the twyres, is almost * See Journal of Iron and Steel Institute, Nov. 1871, p. 409. STUDIES OF BLAST FURNACES. 25 instantaneously transformed into carbonic oxide,* and this gas, in its passage up the body of the furnace, acts more or less directly in reducing ores-that is to say, with or without the aid of the solid carbon. The reduction of the oxide of iron in the blast furnace may take place in three different ways, according to the portion of the furnace we examine. In general, the oxide of carbon (CO) is transformed into CO2, which escapes as such by the furnace top without other reaction. In other positions, the CO02 thus produced becomes again, partially at least, CO by burning solid carbon, which comes in the end, both in its chemical and calorific relations, to be the same thing as if the solid carbon acted directly on the oxygen of the ores, yielding thus either CO2 or CO. These three ways of reduction may be represented by the following formulas:1. 3CO + Fe203 = 3C02 + 2Fe; 2. 3C + 2F203= 3CO2 + 4Fe; 3. 3C + Fe203 = 3CO + 2Fe. It may be at once remarked that the two first ways of reduction are not in fact realizable, if we adopt the propor* We know by the experiments of MM. H. Deville and Cailletet, that near the twyres there is a mixture of unconsumed air and of carbon in minute state of subdivision, by the fact of dissociation; but higher up, the temperature falls sufficiently to determine the definite combination of carbon and oxygen, in the form of carbonic oxide. As to the question, whether in the first moments CO2 or CO be produced, it is simply impossible to answer it; and, truth to say, almost idle to discuss it. We may, however, remark, that when carbon is burned on fire bars, the CO is not really produced till the bed of fuel be sufficiently thick to allow of C being taken up; and thus there can be little doubt that carbonic acid is produced in the first place. 26 STUDIES OF BLAST FURNACES. tions given in the formulas. In these conditions the metallic iron would be partially reoxidized by the carbonic acid. We know by the experiments of M. Debray, confirmed by Mr. Lowthian Bell, that, in presence of equal volumes of CO and C02, peroxide and metallic iron are both brought to the state of protoxide. But though these two first modes of reduction are impossible taken singly, they generally help, with the third mode, in producing the final result; and, in fact, the gases taken at the furnace-top are always composed of a mixture of CO and C02. According as the one or the other mode of reduction has the greater share in the final result, the proportion of CO or C02 in the gases taken at the furnace-top is the greater. But it is easy to show that these three modes of reduction require very different quantities of caloric; and, in this point of view-that is, in reference to the consumption of fuel-it is not a matter of indifference which of these reactions takes place in blast furnaces.' 4. Quantities of caloric absorbed and given off in blast furnaces. Let us determine the quantities of caloric absorbed and given off in the three modes of reduction we have been considering. The caloric absorbed is the same in all three cases:-it is the caloric which a lb. of oxygen would produce in uniting with metallic iron to make peroxide. Let us put C, for the moment, for this number of calories. In the first case, the number of calories given off results from the transformation of CO into CO2. Now each lb. (or other unit of carbon) produces 2403 calories (referred to Centigrade scale and same unit), in talking up 4 lb. of oxygen from the oxide of iron. thence it follows that for each lb. of oxygen the transforma STUDIES OF BLAST FURNACES. 27 tion of CO into C02 is accompanied by the giving off of caloric of 74 x 2403 = 4205 calories. Thus the difference (C — 4025) represents the calorie required for the reduction of the peroxide of iron under the action of CO passing to the state of C02, for each lb. of oxygen taken up. In the second case, the carbon is transformed into C02 by the oxygen of the ore. Under these conditions the lb. of car~Jon develops 8080 calories in taking up 3 lb. of oxygen, and this gives 3 x 8080 = 3030 cals. for each lb. of oxygen. Consequently C -3030 is the caloric necessary for reduction, when this is effected by the solid carbon yielding C02. Lastly, in the third mode of reduction the reaction would be that the oxygen of the ores produced CO directly by means of the solid carbon. But a lb. of carbon gives off 2473 calories* when it forms CO: and as it then takes up 7 lb. of oxygen, the caloric given off by each lb. of oxygen is 3 x 2473 = 1855 cals. Consequently the difference C — 1855 represents the number of cals. required for reduction when this is effected by solid carbon burning to CO. In order therefore to take up a lb. of oxygen from the peroxide of iron, we have the number of calories given by the following formulas: C - 4205 cals. C -3030 " C- 1855 " * This number, to which we shall have to recur frequently, is determined by the following reasoning. The caloric produced by a lb. of carbon giving CO2 is evidently equal to the sum of the two results of the transformation of C into CO and then of CO in CO2. But 1 lb. carbon gives I lbs. CO, and as each lb. of CO gives off 2403 cal. in burning, we should have for the 3 lbs. - X 2403 = 5607, which leaves for the transformation of C into CO, 8080- 5607 = 2473 cals. 28 STUDIES OF BLAST FURNACES. The value of C is not rigorously known. It may indeed vary with the physical condition of the peroxide, but it appears to be confined between the limits of 4600 and 4500 calories, so that the first mode of reduction above represented is effected almost without absorption of caloric. Again, and whatever may be the value of C, it is evident that this mode of reduction is much the most favorable, and that the third mode is very disadvantageous. It is therefore of importance that the reduction of the ores in blast furnaces should be effected as far as possible by the first mode only-that is to say, by the CO being transformed into C02-or, in other words, without consumption of solid carbon. This is what we shall allude to in future as the ideally perfect working of a furnace. When this mode of working is realized, the reactions will be of the simplest kind. The CO produced near the twyres will reduce the ores and be transformed to CO2, and this in its turn will leave the furnace without reaction on the solid carbon. In this case all the carbon of the charges will pass through the furnace without other alteration than a gradual heating, and this carbon will be finally burned to CO under the action of the blast of the twyres. To realize this ideal working, or at least come as near to it as possible, the reduction must take place in a region of the furnace in which the temperature is relatively feeble, otherwise the CO2 thus generated will constantly re-form CO at the expense of solid carbon. The furnaces must therefore be sufficiently capacious, or sufficiently high to insure that the whole upper region should remain at this comparatively low temperature; but at the same time the ascent of the gases must be so rapid that it shall remain a very short time in STUDIES OF BLAST FURNACES. 29 contact with the solid carbon. It is evident besides that ores easily reduced (soft porous ores) will help to realize the ideal working more than compact siliceous ores. But,. in general, whatever be the ore, the reduction can only take place completely in the hot regions in which the C02 will continually get reconverted to CO, and this will be the case niore particularly with other oxides than those of iron-such as silica,(lime, magnesia, and the oxide of magtesla; the reducof these oxides will always require the direct or indirect aid of solid carbon. ~ 5. The economical working of the furnaces varies with the CO ratio of D in the gases.-From what precedes it results, that the relative quantities of CO2 and CO in the gas given off from the furnace depends essentially on the mode of reduction for a given constitution of the charges. And consequently, the higher or lower proportions between the two gases will allow of our appreciating the degree of perfection of the working of the blast furnace.* One or two examples will be sufficient to prove this. We shall see very soon that in the same ironwork, with the same ores, producing the same No. of pig, the temperature of the blast being the same, we find the proportions in the escaping gases as follows, according to the section and dimensions of the furnaces: 0O3 of the total carbon under the form of CO2t 0'7 " " CO * See, for announcement of this fundamental law, section xxxiv. of Mr. Bell's work. t Abstraction is made here of the CO2 in the flux. We have at present to do with the products of the carbon consumed. 30 STUDIES OF BLAST FURNACES. Co2 which gives for the proportion C the number 0'673; or, in the case where the working is less economical, 0'2 of the whole carbon in the form C02 0.8 " " CO which gives for C0- the fraction 0'392. CO Let us then now calculate the caloric given off:In the first case we have 0T'b.3 X 8080 + 0lb'7 x 2473 = 4155 calories. In the second, 01b'2 x 8080 + Olb 8 x 2473 = 3594 calories. Difference, 561 calories. To obtain the same products, the same quantity of caloric is required. IIence each lb. of carbon burned in the first furnace must be replaced by 1+ 3-594 1'155 in the second, which is, in fact, an increase of from 15 % to 16 o, by the single fact of a smaller production of C02, or of the more energetic action which this CO2 has for the solid carbon in the hot region of the furnace. Let us now compare a good working furnace with an ideal working furnace. CO2 We may take the proportion CO-(- 0'673 as indicating good working. This is, in fact, the case of the best furnaces in Cleveland, when account is taken of the gases arising from the coke and of those of the flux. Let us further suppose, as it is actually the case in Cleveland, that for each lb. of pig produced the consumption of STUDIES OF BLAST FURNACES. 31 pure carbon is 1 lb. and 01b'60 of flux. From these data let us first calculate the weight of carbon contained in the gases for each lb. of pig iron. The coke gives 0'03 of carbon to the pig iron. On the other hand the 0'60 of lime contains 0'60 x 12 - 0'072 carbon. It follows that the gases will contain for each lb. of pig produced:01b'970 the carbon from the coke 0lb'072 from the limestone Total, l1b'042 CO2 But as the proportion above assumed CO = — 0673 corresponds to 0'3 carbon burned to CO2 for 0'7 to CO, we shall have, in the gases escaping at the top, 0'3 x 1'042 = 0'3126 of carbon to the state of CO2 0'7 x 1'042 =- 07294 " CO 1.0420 But of the 01b'3126 carbon in CO02, the limestone furnishes 01b'072; there remains then as coming from the coke, 0lb'3126 Olb'072 = 0lb.2406 which gives as the total caloric produced by combustion for each lb. of pig yielded by the furnace0'2406 x 8080 = 1944 calories 0'7294 x 2473 =- 1804 do. Total,. 3748 calories. Now this is the sum of the calories which should be generated in an ideal working, in supposing, for greater simplicity, that in the two cases the blast carries in the same 32 STUDIES OF BLAST FURNACES. number of calories, and that the gases carry off the same dose of sensible heat. The ideal working supposes that the reduction of the oxide of iron is effected by the CO only, without intervention of solid carbon. But it is easy to calculate the weight of CO transformed to CO2 by the reduction of the ores-at least if we take account only of the oxide of iron properly so called. For each lb. of pig iron we have 01b 97 iron and 01b 97 x 3 of oxygen, and this oxygen transforms a weight of CO into CO2, containing a quantity of carbon equal to i of its weight of oxygen. 3 3 or 4- X-7- x 0'97 = Olb 312. The caloric produced by this carbon in its successive transformation into CO, near the twyres, and into CO2, in the zone of reduction, is.. Ob'312 x 8080 = 2521 calories. And thus the CO remaining would have to furnish... 1227 Total equal 3748 calories. 1227 But these 1227 calories require 2473 01 Ob'496 of carbon which has been burned near the twyres, and this gives as the final consumption Olb'030 + 0'312 + 0'496 = 0'838 instead of 11b., which, for the case of an ideal working, gives an economy of 01b'162 per lb. of pig yielded = 16 % CO2 Let us now show that the proportion-C0 will be, in an ideally perfect working, as follows:0'312 + 0'072 (from limestone) = 0'384 carbon in CO2 and. 0496 " CO, or total carbon in gas. 0'83i0. STUDIES OF BLAST FURNACES. 33 11 Hence C02 - x 0'384 =- 1408. 7 CO -- x 0496 = 1'157 C02 therefore C. 1217 2CO ~ 6. The ratio CO is the measure or index of the working oj Blast Furnaces.-It has now been shown by these examples that the ratio C02 in the escaping gases may vary between wide limits. In the modern furnaces of Cleveland, the proportion is generally between 0'50 and 0 70 when the working is good; but it is only 0'35 to 0'40 when the furnace is, in bad condition. And if we could attain to the idealworking, it would be as high as 1'217. We thus see that this ratio is as it were the measure or index of the degree of perfection of the working of furnaces. Of a truth, this ratio is found to vary from one district to another, according to the richness of the ores and their quality, the nature and purity of the fuel, the proportion of flux employed, the number of the pig-iron yielded, etc. etc. But in any given ironwork, or in a given district, this ratio will fall or rise, —will recede from or approach to the ideal figure as the furnace works well. It thus appears very important to be able to determine this proportion exactly by experiments easily multiplied. We have already seen by the examples I have quoted that, when the ratio is known, we can easily calculate the absolute quantities of the two gases, and consequently also the sum of the caloric given off by combustion in the blast furnace. 3 34 STUDIES OF BLAST FURNACES. It has been shown above that the direct determination of this ratio allows of our fixing, in a rigorous manner, not only the quantities of CO and C02, but also very approximately the weight of air for blast and of the escaping gases, and the composition complete of these latter. ~ 7. Weight and composition of the escaping gases.-The ordinary or normal working of the blast furnace gives the data of the weight of the flux and of fuel consumed per unit of pig-iron produced. We know also from the quality of the pig yielded the proportion of carbon united to the iron. We may estimate this at 3 % in ordinary forge iron. Let a the carbon per lb. of pig, b the carbon contained in the flux, and hence p the total carbon in the gases = a + b - 003. If we put y for the weight of CO, and m for the C02 proportion' we have my for the weight of C02, and then for determining y we have the equation(1.) Ty + 1 my = p which formula expresses that the quantities of carbon in CO and C02 are equal to the total carbon in the gases. Hence we have y= 77P 33 + 21m. The oxygen contained in the gases will, in like manner, be equal to the oxygen furnished by the blast, and by the charges of ores and flux, which is expressed by the equation(2.)4 8 (2.) y+ -my=d+x in which x represents the oxygen of the blast, and d represents that furnished by the ores and the CO of the flux. From this equation we find STUDIES OF BLAST FURNACES. 35 77 or (44 + 56mp d \33 + 21 m/ To calculate x, we must first find the value of d. If only the oxide of iron were reduced, it would be easy to determine d exactly. It would be composed of two terms, the oxygen united to b carbon in the CO2 of the flux, that is -3-b; and 3 then the oxygen combined with 0'97 iron or - x 0'97, if we suppose the iron in the state of peroxide; so that we should have 8 3 8 2'91 d --- b + -7x 0o97 = — b + 7 3 7 3 7 But pig-iron generally contains, besides 003 of carbon, other elements, such as silicium, manganese, etc. etc., phosphates derived also from the ores. If we knew the composition of the pig-iron, it would be quite as easy to calculate the oxygen derived from these various elements, as of that furnished by the peroxide of iron. Neglecting this correction, we shall generally get a value {f d; Wthe- too vitlte, because this would be to suppose that these elements united with as much oxygen as the iron, and silica at least gives a much larger proportion. If we start from an average composition of pig-iron, we shall at all events approximate the truth more nearly, and thus obtain values of d and of x very little different from the true values. Suppose a gray forge pig (Nos. 3 and 4 of English marks). We may admit as its composition, if there be little manganese 36 STUDIES OF BLAST EiURNACES. Iron..... 094 Carbon.... 003 Silicium, etc... 0'02 Earthy metals... 001 1'00 According to the equivalents, the silica contains 24 of oxygen for 21 silicium, or 8 for 7; the oxygen derived from the silica = 8- 002; and this expression would be near the 7 truth if, for a part of the silicium, there were substituted phosphorus and sulphur, for phosphoric acid contains 50 for 4Ph, and sulphuric acid contains 30 for 2S.* As to the earthy metals, we know that in Lime, the 0 corresponds to } metal Magnesia... Alumina... a " We may therefore admit, as an approximate average, 4 of Olb 01. At all events, on such a feeble quantity the possible error will be insignificant. According to the above reasoning the corrected value of the total oxygen in the ore and flux will be8 3 8 5 d - b+ - x 0'94 + 7 x 0'02 + - x 001 or d=-b+ (2'82 + 0'16 + 0'05) = 3-b (3803) 3 7 instead of the former expression, which gave b + (2-91). * Sulphuric acid furnishes for equal weight more oxygen than does silica, but this excess is compensated by the circumstance that the greater part of the sulphur of pig-iron is derived from sulph7urats and not from sulphates. STUDIES OF BLAST FURNACES. 37 The value of d being calculated thus, we can deduce that of x, and we have for the weight of air 4'33x, and for that of the nitrogen 3'33x. But this supposes the air of the blast to be perfectly dry, whilst in reality it is always more or less charged with moisture, which adds, of course, the oxygen of the water to that of the dry air. 4 8 The equation 7- Y + 1- my _ d + x, gives therefore for x the oxygen of the air and its moisture united; but it is easy to calculate the values of dry air and nitrogen. It is well known that at the mean temperature of 12~ to 13~ C = (540 to 56~ F), the humidity amounts to about 0'0062 of the weight of dry air, and the oxygen contained - 8 00062 =- 0'0055 of the dry air. Thus if we put z to represent the oxygen derived from dry air and 4'33z that of dry air itself, we have — x = z +(0'0055)( 4'33z = (1 + 0'0238)z and consequently z 1- 0=9767x - 0'0238 Hence the weight of nitrogen. = 3'33 x 0'9767x "6 dry air. = 4'33 x 0.9767x "4 moist air - 1'0062 x 4'33 + 0'9767x - 433 x 0'9828x. In reference to this indirect determination of the mass of air blown through the twyers, it is worth observing, that though it is not rigorously correct, as it depends on a sort of theoretical analysis of the pig-iron, it is nevertheless much more exact than any other mode. It may, of course, be rendered as exact as possible, by ascertaining by proper 38 STUDIES OF BLAST FURNACES. chemical analysis what is the true composition of the pigiron.* ~ 8. Agreement of the formulas with the complete analysis.We may conclude from what precedes, that to get the composition of the escaping gases, it is sufficient to determine by experiment the ratio C- m. This allows of our calculatCO ing exactly the quantities of C02 and CO, and very approximately the proportion of nitrogen: and we deduce besides, with the same degree of precision, the weight of blast. All that is neglected is the hydrogen. But in blast-furnaces using coke, the influence of hydrogen is almost nothing. The hydrogen can only come from two sources, the moisture of the air, and the hydro-carburetted gas, which remains in * The other methods of determining the mass of air are the three following: The first consists in assuming the ideal working of the furnaces-that is to say, in supposing that all the carbon of the coke reaches the twyers intact, and then calculating the oxygen corresponding. But we have seen above (Sec. 5) that even in the case of good working the carbon reaching the twyers may be 16 per cent. less than the total carbon of the coke, which, of course, involves an erroneous estimate of the air. The second method, based on the formula for the outflow of air by a conical mouthpiece, gives a still higher figure. This formula, habitually used as given by d'Aubuisson, Karsten, and Weislarch, gives the volume of air which has no other resistance to overcome than the counter-pressure of the atmosphere; whilst, in fact, the blast meets in the furnace a resistance greatly above this, and which no experiments can determine. Besides this, all the air does not pass by the eye of the twyers; a quite notable fraction is thrown back outside. The third method, that based on the volume passed through by the piston of the blowing cylinder, is quite uncertain, because neither the losses by the quantity thrown back, above referred to, nor the losses by the V ports and valves, and in the hot-blast stones, and from other imperfections, can be determined. STUDIES OF BLAST FURNACES. 39 even the best made coke-but this hydrogen is very little, and acts with the CO in reducing the oxide of iron. It also becomes transformed into steam in the upper part of the furnace. Only a small fraction escapes with the gases without being oxidized. Mr. Bell never found more than 0'001 of hydrogen in the gases of Cleveland and Ebelmen, at most, 0'0013 to 0'0018 in the three works of Vienne, PontEveque, and Seraing. This small proportion has no influence on the working of thle furnaces, and may certainly be neglected in the practical calculations with which we are now engaged. There is no question at present of blast-furnaces working with raw coal. Let us now show how well the formulas we have found correspond with the results found by Mr. Lowthian Bell by two examples:Let us take, first, the small furnace of Clarence Works of 1853 (see ~ 2), the height of which is 48 feet, and the internal capacity 6000 cubic feet. The consumption per ton of iron is 1'45 tons of coke, or 1'318 of pure carbon, and.3 of flux. We have in the formulas of ~ 17 a = 11b'318 t" b = 0'12 x 0.i- i0''06 hence p = lb'318 + 0'06 - 0'03 = 1"'3S4. On the other hand, the analysis of the gases gave CO2.. 11'80 CO... 3050 Az /,;. 57'60 H... 0.10 100'00 40 STUDIES OF BLAST FURNACES. and from this we deduce:C02 11'80 -or mrn = 5 = 0'387 CO 0.50 77 x'b38 591 CO= y = 21 591 Y 33 + 21 x 0'387 CO -- my =- 2-9i x 0'387 -= -002. 8 1 8 0 (30.3) =-0 J6 + 0-423 = 0"' 679 2'591 x'91 (44 + 56 x 0.387) - 06783 = 1'1b531. 77 z = 0'9767 x 1-53- 1 "i-'4)5 and the nitrogen = 3-33 x 1495 -b= 4'978, which gives as the weight of gas per lb. of pig yielded CO02... 1b'002. CO. 21b'591. N 4lb'978. Weight of dry gases 8]-b'571. and Mr. Bell's complete analysis gave C02. 1lb'002 CO 21b.591 N. 4b'893, a difference of 0.085, or less than 2 % 81b'486. Let us now take, as a second example, the blast furnace of 1866 at Clarence Works, height 80 feet, capacity 11,500 cubic feet. The consumption per lb. of pig is 1'125 lb. of coke - 1'020 of pure carbon, and 0'683 of flux and limestone. a = 11b'020 b 0b'12 x 0'683 =0 00$2 therefore p = l1b'020 + 0'082 - 0'03 = 1'072. STUDIES OF BLAST FURNACES. 41 The analysis of the gases gave CO... 17'30 CO... 25.20 N... 5340 H... 0410 100'00 Hence co orm 1 - 0'6865 CO 25'2 ~o = Y 77 x 1'072 82'544 _ 1740. 33 + 21 x 0'6865 = 47'4165 C02 = my =- 1'740 x 0'6865 =... 14195 d = 8 x 0082 + 1 (3'03) = O0b 219 + (')42 ='642 3 7 7= (44 + 56 x 0'6865)- 0G42 = 1863 —- 0i3 2 = 1b.221 z - 0'9767 x 1'221 - 1 b 4192 and N = 333 x -1192 = 3'"'9)9. which gives the following as the quantities of gas per lb. of pig yielded:CO2.... 14195 CO..... 1-740 N........ 3'969 weight of dry gases 6'904 and comparing this with the complete analysisCO2. 14195 CO. 1740 N. 3'965, a difference of 0'004 or 041 %, we see thus that the agreement of the formulas is as exact as possible, and indeed, by pure chance, greater than we had 42 STUDIES OF BLAST FURNACES. any right to expect; for the method of analysis, or rather the method of taking the specimens of gas for analysis, adopted by Mr. Bell, does not admit of perfect exactness. Although the results given by Mr. Lowthian Bell are the means of several specimens, it cannot be admitted that specimens taken almost instantaneously really give the true composition of the gas of a blast furnace. Ebelmen himself said, in speaking of the analysis of the gases atf Seraing, "We must conclude from this that the analysis of the escaping gas of the furnace does not represent the mean composition of the gaseous current."* And yet Ebelmen looked only to taking the means of the different gaseous currents at a given instant, whilst in order to have a clear idea of the working of a blast furnace, not only must we have the exact mean of all the currents escaping at a given instant, but of the true mean of a period of several hours. This important point has not been i~ed by any of the apparatus hitherto employed, and in taking specimens the following system is therefore proposed. ~ 9. A method of taking specimens securing a mean of all the gases during several hours. This system is borrowed from the researches of MM. Scheurer-IKestner and Ch. Meunier on the products of combustion of coal.* In order to obtain an exact mean a certain volume of the total gaseous current which passes from the top of the furnace to the boilers or heating stoves, etc., is drawn off continuously during several hours, and as it would be impracticable * Annales des Mines, t. xix. 4e serie, p. 127; also Note I. Appendix. f Bulletin de la Soceite Industrielle de Mulhouse, 1868. STUDIES OF BLAST FURNACES. 43 to collect the totality of the gases thus drawn off, a certain fraction is withdrawn in the same manner and continuously into a Mariotte's jar filled with mercury, containing about 3 litres. The general arrangement of the apparatus is as follows:Into the main pipe, which carries off the gases, there is passed a copper tube m n of 1 centimetre in diameter to 11 centimetres (a half-inch tube), fig. 13, of a length about double the diameter of the main pipe in question. The part inside the main pipe has a slit throughout that length, as at p. q, about l a millimetre wide ( 1' inch). This allows of the gases being drawn uniformly from every part of the current. The part of the copper tube outside the main pipe passes through a refrigerator on Liebig's system. Lastly, the extremity of the tube communicates by means of an Indiarubber junction with the leaden pipe which serves as exhaust. This is composed of a kind of trompe a b, provided with a cock, which allows of the current of water being regulated, and with a branch c d of greater or less' length, according to the locality. This latter is soldered to the vertical tube a b, a little below the water-cock, and is also provided with a cock, which, working in concert with the other, serves to regulate the flow of gas. It is the end of this branch c d which is united to the copper tube m mI by a joint-piece of India-rubber. Lastly, the lower end of the trompe opens into a cistern of water, which would in fact allow of measuring the gas drawn off by receiving it for a certain number of minutes under a glass receiver. It might happen in many cases where the pressure of the gases in the main tube is strong that the trompe could be dispensed with, and the gas be taken off at once-into the 44 STUDIES OF BLAST FURNACES. lower cistern without using the current of water. But in any case it is more prudent to provide the trompe. It is a simple means of regulating the flow of the gases. It may be made to come at the rate of three or four litres per minute. Now, to collect a certain fraction of this gas-two or three litres in the course of several hours —it is only necessary to use the Mariotte vase above mentioned. For this purpose the tube m n is provided with a small tube h not far from its outer extremity. A bit of India-rubber tubing makes the communication with the straight tube of the Mariotte vase. The flow of mercury is regulated by a bent tube with cock, which may be raised or lowered at pleasure. And then a second upper tube of the Mariotte vase has also a tube with a cock g, which is only used when the gas is drawn off for analysis. When the Mariotte vase has to be filled, the mercury must be let in by the vertical tube till it is full, and overflows by the cock g to expel all air. This cock is then closed, and the mercury rises to the top of the straight tube. Then by means of the India-rubber the connection between this straight tube and the tube h of the copper tube m n is made. If the gas does not come off spontaneously by the India-rubber, a slight aspiration must be applied so as to expel all air it may contain, and then make the joint with the straight tube of the Mariotte vase. What has been said above is sufficient to explain the working of the apparatus. It appears that by a double system of aspiration specimens representing as exactly as possible the average of the gases flowing from the furnace during several hours may be taken for analysis. It will of course be well, should the tension at the moment of charging be very different from the general tension, to desist from STUDIES OF BLAST FURNACES. 45 drawing off the gas until a certain interval has passed, until the usual regime is re-established. As to the analysis of the gases thus collected nothing is more simple, as it is only required to determine the proportions of CO. It is not necessary to measure or weigh the gas which has to be examined. The way to operate is as follows: The gas comes out slowly by the cock g from the Mariotte's vase, by letting in mercury by the straight tube. The gases are dried in U tubes with chloride of calcium, or pumice stone with sulphuric acid. The carbonic acid is taken up by potash tubes. Burn the carbonic a6'' (CO) by the oxide of copper, retain the water formed by the small quantity of hydrogen present, and then determine the carbonic acid produced from the carbonic oxide by means of a second system of potash tubes. This analysis will only be inaccurate in cases'where the gases contain appreciable quantities of carburetted hydrogen, which never takes place when the furnace is working with coke. A last precaution is perhaps necessary in taking the specimens of gas. There are furnaces which smoke a good deal, or in which the gases carry off quantities of fine dust. In such cases the slit in the copper tube might get obstructed more or less. This happened to M. Scheurer-Kestner in his experiments when there was much smoke. This difficulty may be overcome as this able chemist did it. A little rake, composed of a short slip of copper put into the copper tube, could be drawn backwards and forwards by a rod passing on the outside, and thus the slit kept clear. Having determined the ratio CO, the mean temperature 46 STUDIES OF BLAST FURNACES. of the gases should be determined. When the mine is not hydrated ores the temperature of the gases may rise to 400~ or even 600~ C., which renders the mercurial thermometer inapplicable, and there the thermo-electric pyrometer, or the resistance thermometer of Siemens, or the pyrometer of Lamy, based on the variable tensions of C02 derived from the decomposition of the carbonates of lime and magnesia.* ~ 10..Determination of the caloric consumed in Blast Furnaces. -Suppose we have determined the two elements we have C02 been considering CO= m, and the temperature of the gases as they leave the furnace. Let us now see how we can employ these elements to determine the working of the furnace. The question is to compare exhaustively the caloric received and the caloric consumed. It has been already shown how the caloric generated in the furnace by combustion may be calculated, when we know the total weight of CO2 and CO in the escaping gases. Further on it will be shown how the caloric produced near the twyres-in the zone of fusion, and that generated in the zone of reduction, may be separately estimated. In both cases the caloric carried in by the hot blast must be added to the caloric produced in the furnace, in which there is no difficulty if we know the temperature of the blast. It is the sum of these two quantities, caloric produced and caloric thrown in, which makes the total quantity received. For the present, let us show how the caloric consumed may be determined. It is composed of four parts:1. The caloric absorbed by the reduction of the ores and * Comptes Rendus, tome lxix. p. 347. STUDIES OF BLAST FURNACES. 47 by the fusion of the pig-iron. This is a constant element for a given quality of pig, and one which varies very little for different qualities of pig. 2. The caloric absorbed by the fusion of the slags, the decomposition of the limestone, the evaporation of the water in the coke and in the charges of mineral, and lastly, the decomposition of the water in the air. This second part is essentially variable, not only on account of the different quantities of lime used, and of water in the ore and fluxes, but also from the very varying composition of the slags, which on this account require very different quantities of caloric for their fusion. 3. The sensible heat carried off by the gases. This is also a variable element, but always easily calculated when we know the composition and temperature of the gases. 4. The caloric lost by radiation from the walls of the furnaces by contact, or by artificial means of cooling. Some experiments have been made to determine the losses in this way, but in general they can only be appreciated by deducting from the caloric received the sum of the quantities due to the first three causes. Let us now endeavor to estimate the value of these different elements. ~ 11. Caloric absorbed by the reduction of the ores and the fusion of the pig-iron. —We may here admit as in ~ 7 that the pig-iron contains 0'94 of iron, and 003 of carbon, and 0'03 of silicium, phosphorus, sulphur, and earthy metals, etc. The caloric absorbed by the reduction' is equal to that given off by 0'94 iron burned to the state of peroxide, plus the caloric given off by the oxidation of 0'03 silicium, phosphorus, etc. 48 STUDIES OF BLAST FURNACES. The caloric produced by the oxidation of iron has been determined by several experimenters. By burning iron in oxygen Dulong found that the caloric produced for each lb. of oxygen is 4327 calories.* Supposing there was formed magnetic iron or Fe304, this would amount per lb. of iron to (4 x 28) x 4327 2 x 4327 1648 calories, 3 x 284 2or, applying the law of Welther, for the passage of Fe'04 to Fe203 per lb. of iron giving peroxide, 1854 According to Mr. Andrews quoted by Mr. Bell the caloric produced per lb. of iron giving Fe304 is........1582 " and this gives for the peroxide.... 1780 Again, Favre and Silbermann* found for the transformation of a lb. of iron into protoxide by the wet way was..1352 " which gives for the peroxide. 2028 " If we adopt the mean of these three determinations we have 1887 calories. This is the figure we shall adopt for the caloric absorbed in the reduction of the peroxide of iron for each lb. of metallic iron yielded. But it must be borne in mind that this number is only a more or less accurate approximation. Not only the experiments quoted do not agree with each other, but we do not know that the law of Welther is exact for the transformation of Fe304 and FeO into Fe203; and besides, the quantities of caloric given off and absorbed vary with the density and molecular condition * Annales de physique et de chimie, 3e serie, tom. viii. t Ibid., tom. xxxvii. p. 435. STUDIES OF BLAST FURNACES. 49 of the products. Lastly, if we accept the experiments of Despretz, we get a much higher number. According to this physicist the combustion of iron produces 5325 per lb. of oxide, which corresponds to 2019 per lb. of iron passing to the state of Fe304, and 2271 when the metal is transformed into the peroxide.* As to the caloric arising from the oxidation of the 0'03 of silicium, phosphorus, earthy metals, etc., it is still more difficult to get accurate data. We know from the experiments of MM. Troost and Hautefeuille, that the caloric produced by the oxidation of silicium is 7830 calories, and according to Mr. Andrews the oxidation of phosphorus yields 5767 calories. We have no knowledge of the caloric corresponding to the earthy metals. But as silicium is generally the predominant element, we shall not probably be far wrong in adopting 7000 calories for the caloric of each lb. of these elements. It is also probable that the combination of silicium with iron produces caloric, and therefore we may with more confidence reduce the number 7830 calories formed for pure silicium. We may therefore admit that the * Let us here call to mind that the 1887 calories per lb. of iron corresponds to 1887 X 7 = 4403 cals. per lb. of oxygen. This is the value of C in ~ 4. It follows hence that the reduction of peroxide of iron by CO is accompanied by slight absorption of caloric, 4403 - 4205 = 198 calories. Whilst if with Mr. Bell we adopt 1780 calories found by Andrews, we have per lb. of oxygen 1780 X - = 4153 calories, from which would follow that there is a slight disengagement of caloric at the moment of reduction by CO, amounting to 52 calories. 4 50 STUDIES OF BLAST FURNACES. reduction of the ores, fluxes, etc., will absorb for each lb. of iron yielded For the iron proper.. 0 lb. 94 x 1887 = 1774 cals. For the other elements. 0 lb. 03 x 7000 = 210 " therefore, the caloric absorbed by the reduction = 1984 " And we may at once observe that of these 1984 cals. about 1700 are consumed in the upper part of the furnace, and about 250 to 300 in the lower regions of high temperature. To the caloric of reduction must be added that of the pigiron in fusion. This is composed of three parts-the caloric absorbed by pig-iron in its passage from ordinary temperatures to that of fusion-the caloric necessary for liquefaction (the latent heat of fusion), and lastly, that consumed by the pigiron in coming to the mean temperature of the hearth. Practically, however, these distinctions are useless. The essential is to know the total heat contained in the pig-iron as it runs from the furnace. This varies with the working of the furnace, and depends essentially on the mean temperature of the hearth, or, in other words, the degree of fusibility of the slags.* If the slags be refractory, such as earthy protosilicates, the iron will be hot, and will run from the tap at a higher temperature than if the slags be rich in manganese and in alkalies-or even if they be bisilicate of two or more bases. We need not therefore be surprised if the estimates of the total caloric of pig-iron, as given by different experimenters, do not agree with each other. Ordinary calorimeters were employed. The caloric taken up by the water from pig-iron in fusion poured into it was estimated. * See Note II. Appendix. STUDIES OF BLAST FURNACES. 51 M. Minary and Re'sal, experimenting with pig-iron fused a second time, just before it began to solidify, found 255 cals.* M. Rinman obtained from pig-iron of different brands, 261 cals., 257, 256, 252, and, on the whole, 46 calories would represent the latent heat of fusion.t Instead of 255, Messrs. Minary and Rlsal found the total caloric 292 calories, in experimenting with gray foundry iron run from a cupola. But the cast-iron from the blast furnace is generally hotter than that of cupolas. M. Rinman found 300 as a mean for the cast-iron from charcoal furnaces with extremes of 270 and 311. Messrs. Boulanger and Dulait giveS — For forge iron —coke furnace. 309 cals. For foundry iron.. 337 " M. Vathaire, on the other hand, found — For white iron.... 280 cals. For gray, No. 3.... 330 " and lastly, Mr. Gillot, civil engineer, found for pig-iron run from a cupola, and as a mean of two experiments made at the blast furnaces of Bizy.. 337' for gray iron from charcoal furnace. Mr. Bell adopts M. Vathaire's figure, 330 calories: and this is the number we shall adopt for gray No. 3, until better informed. But it is evident that experiments have to be * Annales des mines, 5th series, t. xix. page 406. f Melmoire presente6 l'Academie de Stockholm, 15th May, 1865. t Revue de Liege, 1862, t. ii. ~ Etudes sur les hauts-fourneaux. 52 STUDIES OF BLAST FURNACES. multiplied, and especially the dependence of this number, 330, on the greater or less fusibility of the slags, and on the quality of the iron, has to be further examined. As a resume, we may in the mean time adopt, as the caloric absorbed by the reduction of the ores, etc., and the fusion of the iron for gray forge iron, No. 3, 1984 calories for reduction and 330 " for fusion Total. 2314 calories. ~ 12. Caloric absorbed by the fusion of the slag, the decomposition of the limestone, etc.-The slags have very different degrees of fusibility. Many years ago, Sefstr6m and Berthier ascertained that bisilicates and even trisilicates of lime, magnesia, and alumina, are more fusible than the protosilicates, and generally the most fusible silicates correspond to compositions near to bisilicates.* It is on this account that the bisilicate formula is aimed at in all cases where the presence of sulphur or some analogous motive does not demand an excess of lime in the charges. And from this circumstance we see that not only the caloric absorbed by the slag, but that of the iron yielded, must vary, as above indicated, with the chemical constitution of the slags. The difference in the fusibility of slags has been proved by Plattner also, by comparing it with various alloys of gold and platinum. But if fusibility varies with the composition of the slags, so must the total caloric. The earthy singulosilicates, which are little fusible, must take more caloric than the bisilicates of these bases, or than the silicates containing a certain proportion of alkalies, and of * See Note II. Appendix. STUDIES OF BLAST FURNACES. 53 the oxides of iron and manganese. Hence, a diversity of results has been obtained by experiments on slags as by those on cast-iron. For a very irony slag from a cupola, MM. Mineray and RWsal found 336 calories. For a slag, approximating to sesquisilicate of lime and of magnesia, M. Rinman found 441 calories, and for another 430. For a glassy slag from charcoal furnace, having manganese in its composition, and approximating to a bisilicate, M. Gillot found 370 to 380 calories. MM. Dulait and Boulanger found, for a slag of No. 3 iron, 433 calories, and for one from gray iron for foundry, 492. These two latter slags, like the most of slags coming from blast furnaces working with coke, are generally nearly singulosilicates. The first certainly contained oxide of iron. Lastly, M. Vathaire found, for a slag from a coke furnace yielding No. 3, 350 calories; and Mr. Bell found even 572 calories, but considers this number as a too high determination. From what precedes, we see that slags which are bisilicates and contain manganese, do not retain more than 370 to 400 calories in flowing from the furnaces, whilst sesquisilicates retain about 450; and that singulosilicates may take as much as 500 calories when they contain neither iron nor manganese, but, on the other hand, a high proportion of earthy bases. Again, Mr. Bell admits 550 cals. for the total caloric of slags of Cleveland No. 3 iron, by reason of their strong proportion of lime and alumina. In any case, the slags always retain more caloric than the iron. They have both a higher specific heat and a higher latent heat. This latter is as high as 120 cals., according to 54 STUDIES OF BLAST FURNACES. Rinman, for sesquisilicates, whilst that of cast-iron is only 46. But we see from the diversity of results, that in order to have an exact estimate of the caloric absorbed, we should have to make special experiments on each slag. We have more exact experiments on the caloric absorbed in the decomposition of limestone. MM. Favre and Silbermann found the number 373'5 calories for calespar, and 360-6 for arragonite.* Thus, in this case again, the molecular state has a certain influence on the caloricity, and it cannot be affirmed that every limestone, crystalline or amorphous, dense or porous, requires the same sum of caloric for its decomposition. Still, we may admit 373'5 for our present purposes. We have now to estimate the caloric absorbed by the vaporization and decomposition of water. For the evaporation we shall adopt Regnault's number, 606'5 calories. For the decomposition of water, we have 29,003 calories per lb. of hydrogen set free. This is the caloric produced by the combustion of hydrogen to steam.t The result, therefore, is 29,003 = 3222 calories per lb. of water. 9 Let us remark in conclusion, that though the fusion of the slags absorbs caloric, the combination of silica and the bases probably disengages a certain amount of caloric which we cannot estimate. ~ 13. Sensible heat carried off by the Gases.-The caloric k Annales de physique et de chimie, 3d series, t. xxxvii. t 1 lb. hydrogen produces 34,462 calories, the steam being condensed to 00. If water remained in the state of vapor at 00, we must deduct 9 +- 606-5 = 5458-5. Hence the figure 29,003 above given. Compare Bell, section xli. Tr. STUDIES OF BLAST FURNACES. 55 carried off by the gases is easily calculated if we know their composition and their temperature. It is only necessary to consider separately each constituent of the-gaseous mixture. Taking the specific heats determined by Regnault we have per lb. and for each degree Centigrade:For CO2. 0 217 calories. CO.. 0226 N 0'244 " Steam.. 0480 " and we find further on, that, according to the mean composition of the gases of bNist furnaces (coke), the specific heat is as a general average very nearly 0'237. ~ 14. Caloric lost by radiation from the walls of furnace, etc. -The caloric thus lost is composed of several parts. There is the heat carried off by the cooling water, which is easily determined; there is the heat dispersed by radiation from the walls; that which the air carries off in its currents past the walls, and that which passes into the base of the furnace by conduction. These two latter cannot be determined, but we may attempt to determine what is lost by radiation. Mr. Bell made experiments on this subject on a blast furnace on the Wear. He used an oblong vessel of copper holding about nine quarts of water, every side of which except that put to the furnace was cased with flannel and with wood, with interposed thin strata of air. By applying this uncovered side to different parts of the wall of the furnace, Mr. Bell ascertained the caloric given off per unit of surface, and hence for the whole surface of the furnace. In this way he found 56 STUDIES OF BLAST FURNACES. For the Wear furnace per lb. of iron. 186 calories And for the caloric carried off by the water of the twyres, 10,150 lb. of water heated to 9~'16 Centigrade.... 93 Total. 279 " And to this must be added an allowance for caloric carried off by the air currents, and that lost in the foundations. And thus the number 300 or even 400 calories may be adopted for this source of loss of caloric. ~ 15. Determination of the Caloric received by a Blast Furnace.-Let us now return to the caloric produced in the interior of the furnace. Neglecting the caloric resulting from the combination of the elements constituting pig-iron and the slags, the caloric produced is derived solely from the transformation of carbon into a certain mixture of CO2 and CO. This caloric may be calculated, either by deduction from the analysis of the gases, or by considering separately the zone of combustion near the twyre and the zone of reduction in which CO is transferred into CO02. Let us first apply a knowledge of the analysis of the gases. Making use of the notation of ~ 7, we have y - the weight of CO, and my = the weight of CO02, and hence -7-y= the carbon in CO, and 3 my = the carbon in CO2. But the carbonic acid contains b of carbon derived from the limestone, therefore the carbonic acid produced by combustion.only contains(f3- my- b ) of carbon. _, m STUDIES OF BLAST FURNACES. 57 The caloric produced is therefore composed of the two products: yx 2473+( 3 my —b) x 8080 calories (4). Let us now ascertain how this caloric is divided between the two zones. ( One portion of carbon is transformed into CO in the upper part of the furnace,) the remainder descends to the sphere of the twyres, and there again produces CO,)and lastly a part of the total CO arising from these two sources is definitively burned to CO2 by the oxygen of the ores and fluxes. The caloric generated in the zone of reduction is thus composed of the sum of the quantities of caloric produced (1) by this partial combustion of carbon into CO in the upper part of the furnace, and (2) by the formation of CO2 under the action of the ores and fluxes. It is easy to calculate those quantities of caloric respectively. The 0'94 of iron in a lb. of pig-iron were united in the per3 oxide to 7 x 0'94 = 0b'403 of oxygen, and this oxygen unites with a portion of CO containing } x 0'403 = 0'302 carbon. If, then, the C02 thus produced were not partially reconverted to CO, if, in other words, the working of the furnace were what we have termed the ideal, we should find in the escaping gases a weight of C02 containing 01b'302 + b of carbon, b being, as we have said, the weight of carbon in the limestone. But the gases of the furnace contain only (3 my ) of carbon in CO2; therefore Ob 302 + b-( my ) represents the carbon of the portion of C02 which has been reconverted to CO, and as CO2 burns exactly the weight of carbon which it already possessed, this expression will 58 STUDIES OF BLAST FURNACES. represent the ca~rbon burned to CO in the region of reduction. On the other hand, as (a - 0'03) is, according to ~ 7, the total carbon of the coke, minus the 3 % taken up by the pig-iron, we perceive that the carbon burned at the twyres is given by the difference(a.-003)-( 0.302 + b- 3 my ) and hence the caloric produced near the twyres will be (5) i (a-0'03)-( 0'302 + b- my) x 2473 cals. As to the caloric produced in the zone of reduction, it, as we have seen, arises from (1) Carbon burned to CO by the ores, or ( 0302 + b-1 my )x 2473 calories. (6) (2) The CO transformed into CO2 by the ores. Now the CO2 thus formed contains (3 my - b carbon, and corresponds to, my - b ) of CO; (7) which by combustion would give -7_(3 my-b ) x 2403 calories. The sum of these three products must equal the number we have found above by the first method-that is, in starting simply from the analysis of the gases-that is, they reproduce the expression7-yx 2473 + (jmy-b )x 8080. (4) And this, in fact, is easily verified. The sum of the two first expressions (5) and (6) come in the first place to (a 0'03) x 2473 calories. STUDIES OF BLAST FURNACES. 59 This is the caloric produced by the total carbon of the coke transformed to CO. As to the third expression (7), which gives the caloric produced by the transformation of C02, it may be written thus(31 my-b )x 7 x 2403 my b 5607; and as 5607 = 8080 - 2473, we have finally, -7 3my-b) x 2403 = (my-b) x 88- my-b x 3\11 \11 nqlm-b )x 2473 and hence the sum of the three expressions (5), (6), and (7) is (a - 003 my +b) x 2473 + myb)x 8080(8) which is evidently equal to total sum (4); for, according to our notation and equation (1) of ~ 7, we have a + b - b.03 = p and ( 13 m ) y so that the coefficient 2473 in the expression (8) becomes 7 y as in the sum (4). From what we have above said it will now be easy to compare the caloric consumed and the caloric received. It is 002 sufficient to know for each particular case the ratio C m, CO - ml and the values of a and b in the charges referred to the lb. of iron yielded. Let us apply the formulas we have developed to some examples, and first let us take the Cleveland furnaces, which were the subject of Mr. Bell's investigations. ~ 16. First example.-As a first example we take the small furnace of Clarence Works of 1853, already mentioned, ~ 8, and shown in fig. 2. The height is 48 feet and the internal 60 STUDIES OF BLAST FURNACES. capacity 6000 cubic feet. There are 1'450 tons coke consumed per ton iron yield-that is 1'318 of pure carbon. We have therefore per lb. of iron yieldedCarbon in the coke, or a =.. 1'b 318 Carbon in limestone, or b = 0412 x 0'0 0 096' Total carbon..... 1 414 Carbon absorbed by the cast-iron * -.- 0'030 Total carbon of the gases, or p =. 1ib 384 According to the analysis of the gases _ m = 0.387 CO These data give, by the formula of ~ 7, as has been shown in ~ 8, the following results:Weight of the dry Gases. my or CO2 = 11b'002 Carbon contained Ob'2735 =_ ly V; 3 y or CO = -9-591 1 1105 y. 3'33 -- WN - 4'978 A, -. Total carbon. 1b'3840 = p. Weight of dry gas -— 8571 Water from coke - 0'051 Weight of moist gas = 8'622 Weight of Air of Blast. Oxygen of dry air (z). = lb.495 N..... -- 4 978 Weight of dry air... = 6'475 Moisture 0'0062 x 6'473.. = 0 040 Weight of moist air... 61b -513 or 6'513 tons per ton of pig-iron yielded. STUDIES OF BLAST FURNACES. 61 Caloric carried in by the blast.-The temperature of the blast was 485~ C. The specific heat of dry air is = 0.2375, and as that of vapor is 0'48, the mean specific heat of the blast is 0'2375 + 0'0062 x 0'40 = 0'239 1'0062 and this gives, for the caloric carried in by the moist blast, 6'5-i3 x 485~ x 0'239 =-755 calories. Caloric produced in thefurnace. The caloric due to CO2( -i,) x 8080 = (02; D -A i e) x 8080 = 1434 calories. The caloric due to CO3 y x 2473- = -;15 x 2473.. -274 " Caloric produced in the furnace by 1'278 carbon...... 4 80 " and hence caloric from 1 lb. =... 3245 " whilst, if this lb. were completely burned, it would have produced 8080 calories, so that the caloric really developed is only 0'40 of the calorific power, properly so called, of the coke consumed. It will now be shown how this caloric produced is divided between the zone of the twyres and that of reduction. The carbon burned in the zone of reduction is given by the expression, 3 01b 0'302 + b- my = 0'302 + 0 096- 0'2735 = (Pb ~245. 11 62 STUDIES OF BLAST FURNACES. The total carbon burned in the furnace, as above shown, is........ 1288; therefore, the carbon burned near the twyres. =-1'1635, and the caloric prod(!!ced in this zone, 1"1635 x 2473 - 2877 calories. As to the caloric of the zone of reduction, it is composed(1) of carbon burned to CO, or 0'1245 x 2473 =308 calories. (2) of the oxide of carbon 7j311 my-b)- 7 (0 1775) 0 414 calories. transformed to C02 or 0'414 x 2403 ='0995. calories. Hence, we have in the zone of reduction, For carbon burned. 308 calories. For CO burned... 995 Total of zone of reduction 1303 " Caloric of the zone of twyres 2877 " Total caloric produced. 4180 " Caloric carried in by the blast 755 " Total caloric received. 4935 " Let us now compare with this the total of caloric absorbed or utilized by the substances reduced and fused in the furnace. Referring to f 10, the caloric absorbed may be arranged under four heads: (1.) One element, almost constant, which comprises the caloric taken for reduction of the ores and the fusion of the iron, which according to ~ 11, = 2314 calories. STUDIES OF BLAST FURNACES. 63 (2.) Thefusion of the slags, the decomposition of the limestone, etc., ~ 12.-If we take the data abyve given, we findFusion of slags... 1610 x 550 = 885 calories. Decomposition of limestone. 0'800 x 373'5 = 299 " Evaporation of water in coke 0'051 x 606 - 31 Decomposition of vapor in blast 0'042 x 3222 - 129 12 Total... 1344 44 (3.) The caloric carried off by the gases (~ 13).-The gases escape at the mean temperature of 452~ C.; therefore, from the known weight of the gases, we haveFor CO2. 1'002 x 0'217 per 1~c. 0'2175 cals. For CO. 2'591 x 0'226 " 0'5855 " For N. 4'978 x 0'244 " 1'2146 For NO. 0'051 x 0'48 " 0'0245' Total of gases 8'622... " 20421 " and for the mean specific heat of the gases, 2-0421= 0'237, 8'622 a number which is nearly constant in the Cleveland district. Thus, en resume, we find(1.) Caloric taken for reduction and fusion of the iron 2314 cals. (2.) Caloric taken for fusion of slags, lime, etc.. 1344 " (3.) Caloric carried off by the gases... 923 Total.. 4581 and from this we have to deduct as difference 358 " loss by radiation, evection, etc. Total, equal to caloric received. = 4935 ~ 17. Second example.-As second example, we take the blast furnace of the Clarence Works of 1866, already mentioned in ~~ 2 and 8 (fig. 6). 64 STUDIES OF BLAST FURNACES. The elements of this furnace are —height, 80 feet; capacity, 11,500 cubic feet. Coke consumed per ton 1'125 tons, or pure carbon, 1.020 Ore.... 2240 " Limestone... 06831 " Slag produced.. 1'520' " Temperature of blast.. 4850 C. Temperature of gases.. 332~ C. from which we find per lb. of pig-iron produced, Carbon of coke, a =.. lb'020 Carbon of limestone, b = 012 x 0'683 0'082 Total carbon, a b -.. 1'102 Carbon taken up by iron.. 0 030 Total carbon of gases, p = l'b'072 On the other hand, the analysis of the gases gave m- = 0'6865, which, with use of formulas of ~ 7, gives the following results:Weights of Gases. my or CO2 = 1195 Carbon contained, 0'326 = my y or CO 1'740 " l 0'746 = Ty 3'33z or N = 3'969 v Total carbon.i 1'072 = p. Weight of dry gases - 6'904 Water from coke - 0'029 Weight of moist gas = 6933 STUDIES OF BLAST FURNACES. 65 Weight of Air in Blast. Oxygen of dry air (z)... 1lb 192 Nitrogen..... 3 69 Weight of dry air... 5 Li1 Moisture 0'0062 x 5'161.. 0'032 Weight of moist air... 5lb93 or, 5 193 tons per ton of iron made. Caloric carried in by Blast. 5'193 x 485~ x 0239 = -602 calories. Caloric produced in the Furnace. Caloric due to C02: 13 my-b) x 8080 = (0x326 - 0082) x 8080 1971 cals. Caloric due to CO: y x 2473 = 0746 x 2473... 1845 " Caloric produced by 0'990 carbon... 3816 " and hence caloric by 1 lb. carbon. = 3854 " Which gives for the caloric really developed 0'48 of the calorific power of the coke consumed. The 3816 calories divide themselves between the zones of the furnace as follows:-The carbon burned in the zone of reduction is given by the formula: 0'302 + b -1 my = 0'302 + 0'082 - 0'326 = 0'058.* * It is right to call attention here to this number. 0'058 absorbed in transforming C02 to CO is less than the 0'082 of carbon in the limestone, which proves, contrary to Mr. Bell's opinion, that the whole carbonic acid of the limestone is not necessarily transformed to CO in the blast furnace. 5 66 STUDIES OF BLAST FURNACES. Hence the carbon burned near the twyres 0'990 - 0058 = 0'932, and the caloric produced in this region: 0'932 x 2743 = 2305 calories. The caloric given off in the zone of reduction arises from (1.) The carbon burned to CO, - 0058 x 2473... 144 cal. (2.) The CO burned to C02, =(1 mY-b) x 2403-= x 0o244 x 2403 1367 cals. Caloric produced in zone of reduction.. 1511 " Or, to sum up, caloric produced near the twyres 2305 cal. Do. do. zone of reduction.. 1511 Total caloric produced by combustion.. 3816 cal. Caloric carried in by the blast. 602 cal. And hence, total caloric received 4418 cal. We can already perceive, by comparing this total of caloric received with that of the first example, ~ 16, that to produce the same useful effect, the supply to this second furnace is 517 calories less, and the difference is altogether in the caloric of the region of the twyres. The caloric generated in the zone of reduction is even 208 calories more in the large furnace than in the small. Let us now estimate the caloric absorbed. (1.) For the reduction of the ores, and the fusion of the pigiron r. e 2314 cals. (2.) For fusion of slag and decomposition of limestone, etc., ~ 12 gives: STUDIES OF BLAST FURNACES. 67'Fusion of slags.. x' 0Q 836 cal. Decomposition of lime 0'685 x 373'5 - 255 Vaporization of water of coke.. 0029 x 606 - 18 Decomposition of vapor in blast... 0032 x 3222 - 103 Together... 1212 cal. 1212 Caloric carried'i by gases: 6'933 x 332~ x 0'237*. 545 Total. 4071 And hence loss by radiation and evection (difference)....... 347 Total of caloric reeived. 4418 cals. ~ 18. Third example.-As third example, we take with Mr. Bell the Ormesby blast furnace, built inl 1867 (fig. 8). The elements of this furnace are:Height, 76 feet; capacity, 20,500 c. feet. As at Clarence Works, the ores smelted are calcined Cleveland ores. The yield is 63 tons of pig, Nos. 3 and 4, in 24 hours, which corresponds to 326 cubic feet capacity per ton of iron: Coke consumed per ton, 1'100 tons, or of pure carbon, 1'017 t. Ore.... 2440 " Limestone... 0'625' " Slag produced.. 1'485 " Temperature of blast 780~ v Temperature of gases 412~ * 0237 is, according to ~ 16, the mean specific heat of the gases. 68 STUDIES OF BLAST FURNACES. And from these data we deduce per each lb. of iron yielded: Carbon of coke, a.... = 1017 Carbon of limestone, b = 0'12 x 0'625 = 0'075 Total carbon, a + b.. 1'092 Carbon absorbed by the pig... 0030 Total carbon in the gases p. - 1'062 On the other hand, the analysis of the gases gave m = 0'542. With these data, the formulas of ~ 7 give the following results:Weight of Gases. my = C02 = lib'000 carbon contained Olb *272 - my. y e CO -=1 *845 do. do. 0'790 = 3-y. 3333 z or N-3.745 Total carbon 1'062. Weight of dry gases, 6lb'588 HO from coke. 0'028 Weight of moist gas, 6'616 Weight of Air in Blast. Oxygen of the dry air (z).. 1b'124 N. 3'743 Weight of dry air... 4'867 Moisture 0'0062 x 4'867.. 0'030 Weight of moist air. 4'897 Caloric carried in by Blast. 4'897 x 7800 x 0'239 = 913 calories. STUDIES OF BLAST FiURNACES. 69 Caloric produced in the Furnace. Caloric due to C02: (13% my-b) 8080 = (Olb *272-0 075) x 8080 =. 1592 cals. Caloric due to CO. y x 2473 = 0'790 x 2473.... 1954 " Caloric produced by 1'062 — 0075 = Ob'987 carbon 3546 " And hence, caloric produced per lb. carbon. 3593 " And this gives for the caloric really developed 0'44 of the calorific power of the coke consumed. These 3546 calories are divided in the following proportions between the two zones of the furnace. The carbon burned in the zone of reduction is given by 0'302 + b - my -= 0b *302 4- 0'075 - 0'272 = Olb'105 Therefore the carbon burned near the twyres = 01b'987Olb 105 = 0'882, and the caloric produced in this region, 0'882 x 2743 = 2181 calories. The caloric generated in the zone of reduction arises from (1.) carbon burned to CO - Ob'105 x 2473 =. 260 cals. (2.) CO transformed to C02, or 73- my-b) x 2403 =xx 0-197 x 2403 = 1105" Caloric produced in zone of reduction. 1365 " Or, en resume, Caloric produced near twyres. 2181 Caloric from zone of reduction. 1365 " Total caloric from combustion 3546' Caloric taken in by blast.. 913 " Total caloric received by the furnace 4459 " 70 STUDIES OF BLAST FURNACES. On the other hand, the caloric absorbed is composed of (1.) That for reduction of ore and fusion of pig (a constant). 2314 cals. (2.) For fusion of slags, and decomposition of limestone according to ~ 12. Fusion slags. 1'485 x 550 = 817 cals. Decomposition of limestone... 0625 x 3735 = 233 Evaporation of HO in coke... 0028 x 606 - 17 Decomposition of vapor in blast... 0'030 x 3222 = 97 Together. 1164 1164 cals. (3.) For the sensible heat of gases, 6lb'616 x 412~ x 0'237. 646 Total. 4124 Hence (4.) loss by radiation and evection (by difference)...... 335 4459 ~ 19. _Fourth example.-This is the blast furnace at Consett, smelting a mixture of calcined Cleveland ores and red hematite of Cumberland. The elements of the furnace are, tHeight 55 feet, capacity 9300 c. ft. Mean daily yield, 55 tons of pig-iron No. 5, which gives 170 cubic feet capacity per ton yielded. STUDIES OF BLAST FURNACES. 71 Coke consumed per ton of iron 1'137 tons, or pure carbon 1.035'5 Ore..... 2'083 Lime.... 0412 Slag produced... 0'960 Temperature of blast. 454~0 C. Temperature of gas. 6-7-7 C.,. From these data we have per lb. of pig-iron yielded, Carbon in coke, a.= lb -0355 Carbon in limestone, b = 0'12 x 0'412. = 0.0495.~. a +.... - 1 I'850 Carbon absorbed by iron. 0'0300 Total carbon in gases, p = Ilb'0550 On the other hand, the analysis of the gases gave m = 0'502. And now, with these data, we have the following results by the formulas of ~ 7:Weight of Gases. my or CO2 = Olb'9355 Carbon contained = Olb'2555 = my y or CO = lb'8655 do. do. = 0'7995 -— y Total carbon, p = lb'0550 = p 3-33 z or N= 3'8760 Weight of dry gases. 6 -6770 Water from coke.. 0'029 Weight of moist gas. 6lb'706 72 STUDIES OF BLAST FURNACES. Wei.qght of Air in Blast. Oxygen of dry air (z).. lb' 164 Nitrogen........ 3 *876 Weight of dry air. 5'040 Moisture 0'0062 x 5'040. 0'031 Weight of moist air. 51'071 Caloric carried in by Blast. 5 071 x 4540, 5 x 0'239 = 551. Caloric produced in the _Furnace. Caloric due to CO2 ( my - b x 8080 = (02555 - 0'0495) x 8080 =1664 cals. Caloric due to CO. y x 2673 = O-b'7995 x 2473... 1977 cc Caloric produced by 1"b'0055 of carbon (a - 03) = 3641 cals. Therefore, caloric by 1 lb. of carbon.. = 3621 " Which gives as the caloric really developed 0'45 of the calorific power of the coke consumed. These 3641 calories are divided between the two zones of the furnace as follows: The carbon burned in the zone of reduction given by: 0 302 + b - my - Olb'302 + 0'0495 - 0'2555 = 0'096 and therefore the carbon burned near the twyres 1'0055 - 01b'096 = 0'9095, and the caloric produced in this region, 0'9095 x 2473 = 2249 calories. The caloric generated in the zone of reduction arises from STUDIES OF BLAST FURNACES. 73 (1.) The carbon burned to CO, or 0'096 x 2473..... 237 cals. (2.) The CO transformed to C02, or (3 (lmy b) 2403 = 3 x Olb206 X 2403 1155 " Caloric produced in the zone of reduction. 1392 Add caloric produced at the twyres.. 2249 Total heat of combustion 3641 Caloric carried in by blast.... 551 Total caloric received by the furnace 4192 On the other hand, the caloric absorbed is composed of, (1.) reduction of ores and fusion of pig-iron, according to ~ 11 (constant)....... 2314 cals. (2.) For the fusion of slags, ~ 12. Olb 960 x 550 = 528 cals. Decomposition of limestone.. 0'412 x 373'5 - 154 Evaporation of water of coke. 0'029 x 606 = 18 Decomposition of ItO in air.. 0'031 x 3222 = 100 Together 800 cals. 800 (3.) For the sensible heat of the gases (~ 13), 6lb 706 x 4770 x 0'237.... 758 cals. Total 3872 (4.) Loss by radiation and evection, etc. (difference) 320w Total equal to the caloric received 4192 cals. ~ 20. Fifth example.-This is the blast furnace No. 4 of Consett, smelting like the preceding one, a mixture of calcined 74 STUDIES OF BLAST FURNACES. Cleveland and red hematite of Cumnberland ores. The elements of this furnace are: Height 55 feet, and capacity 10,200 c. feet. The mean yield is 60 tons of Nos. 4 and 5 in 24 hours, or 195 c. feet per ton of pig-iron. Coke consumed per ton 0'900 ton, or pure carbon 0'819. Ore.... 2083 v Limestone... 0'406, Slag produced.. 0'950 Temperature of blast 710~ C. Temperature of gases 248~ C. ~ And hence per lb. of pig-iron yielded:Carbon of coke, a.... 08190 Do. of limestone, b = 0'12 x 0'406 = 0'0485 Total carbon, a + b.. = 0 8675 Carbon absorbed by iron... 0 0300 Total carbon of gases, p = 01b'8375 The analysis of the gases gave m = 0'623. Applying the formulas of ~ 7 we find, Weight of Gases. my or CO2 = 0 -8715 Carbon contained 0'2375 -3- 1my. y or CO = lb' 4000 do. do. 0'6000 _ — ty. 3'33 z or N 2'8670 Total carbon 0-8375 Weight of dry gases 5'1385 Water from coke 0'0225 Weight of moist gases 1. 5b'1610 STUDIES OF BLAST FURNACES. 75 Weight of Air in Blast. Oxygen of dry air (z).. -.'b'861 Nitrogen....... 2 867 Weight of dry air.... 3 728 Moisture in air, 0'0062 x 3'728. = 0 -023 Weight of moist air.... = 3b751 Caloric carried in by Blast. 3'751 x 718~ C. x 0'239 - 643 calories. Caloric produced in the Blast Furnaces. Caloric due to C02: x ( rny- b) x 8080 -(02375 - 0'0485) x 8080 = 1527 cals. Caloric due to CO. y x 2473 = 0'600 x 2473... -1484 " Caloric produced by 01b'789 of carbon = (a - 003) = 3011 Hence caloric produced by lb-. = 3816 Which gives for the caloric really produced in the furnace 0'47 of the calorific power of the coke consumed. The 3011 calories are divided as follows between the two zones of the furnace: The carbon burned in the zone of reduction is 0'302 + b- my- Ob'*302 + Olb'485 Olb'2375 = 0'113 and therefore the carbon burned near the twyres, O0b'789 - 0'113 = 0'676, and the caloric produced in this region, 0'676 x 2473 - 1672 cals. 76 STUDIES OF BLAST FURNACES. The caloric generated in the zone of reduction arises from (1.) Carbon burned to CO, or 0'113 x 2473.... 279 cals. (2.) CO transformed into C02, -- 1my —b x 2403 =-3- x 0'189 x 2403 - 1060 " 11/ 3 Caloric produced in the zone of reduction. = 1339 cals. which, en resurne, gives Caloric produced near the twyres.. 1672 cals. Do. do. zone of reduction.. 1339 Total caloric of combustion.. 3011 Caloric carried in by the blast... 643 Total caloric received by the furnace. 3654 cals. On the other hand, the caloric absorbed includes, (1.) For reduction of ores and fusion of iron (~ 11) constant....... 2314 cals. (2.) For fusion of slags, decomposition of lime, etc., ~ 12:Fusions of slags. 0'950 x 550 = 522 cals. Decomposition. 0'406 x 373'5 = 152 Evaporation of HO in coke.. 0'0225 x 606 = 14 Decomposition of vapor in blast 0'023 x 3222 = 74 Together 762 762 (3.) For the sensible heat of the gases (~ 13), 5'1'161 x 2480 x 0-237. 303 Total.. 3379 cals. Hence loss by radiation, evection, etc. (difference) 275 Total equal to caloric received. 3654 cals. STUDIES OF BLAST FURNACES. 77 ~ 21. Consequences derived from the preceding examples:Before applying this method of analysis of the working of blast furnaces to other examples, let us endeavor to extract from the numbers we have arrived at the lessons they teach. Let us examine in turn the influence of the cubaci and of the height, of the furnaces, and then that of the temperature of the blast. For this purpose we have gathered into a single table the most salient results of the examples we have chosen as illustrations. 78 STUDIES OF BLAST FURNACES. SYNOPTICAL TABLE OF RESULTS OBTAINED. Elements of the Furnaces. I L X. Internal capacity of the furnaces c.feet 6000 11,500 20,500 9300 10,200 Height of the furnaces... feet 48 80 76 55 55 Yield in 24 hours.tons 30 38-6 63 55 60 Capacity per ton yielded in 24 hours c. feet 195 300 320 160 170 Nature of the pig classified by Nos. 3 and 4 3 and 4 3and 4 5 4to 4'5 Ore consumed per lb. of pig yielded lbs. 2-440 2448 2440 2083 2 083 Flux consumed per lb. of pig. 0"800 0'683 0'625 0412 0.406 Total carbon burned " 1..288 0'990 0'987 1-0055 0-789 Carbon burned in the zone of reduction.. C.. t).. ~. " 101245 0-058 0105 01096 0-113 Temperature of blast.. degs. C. 485 485 780 454-5 718 Temperature of gases... " 452 332 412 477 248 Value of m - C2.. " 0:387 06865 0'542 0 502 0623 Caloric developed in furnace for each lb. of carbon burned. cals. 3245 3854 3593 3621 3816 Weight of blast... s. 513 519 4.897 5071 3 751 Weight of gases... 8622 6933 6616 6706 5,161 Caloric of combustion in the zone of reduction. per lb. of pig yielded cals. 1303 1511 1365 1392 1339 Caloric of combustion in the zone of the twyres. " 2877 2305 181 2249 1672 Total caloric of combustion. " 4180 3816 8546 3641 3011 Caloric carried in by blast. " 755 602 913 551 643 Total caloric received..... 4935 4418 4459 4192 3654 Caloric of the zone of fusion — Sum of the caloric of combustion near the twyres and that carried in by blast....... " 3632 2907 3094 2800 2315 Caloric absorbed by the reduction of the ores and fusion of the iron " 2314 2314 2314 2314 2314 Caloric absorbed by fusion of slags and decomposition of limestone, etc. " 1344 1212 1164 800 762 Sensible heat carried off by gases. " 923 545 646 758 303 Caloric lost by radiationRadiation from the furnace walls 1 etc. (determined by difference) " 354 37 ~- 335 320 ro 275 Sum of the caloric consumed.. " 4935 4418 4459 4192 3654 STUDIES OF BLAST FURNACES. 79 Let us remark now, at once, on the subject of the five examples compared in this synoptical table, that the furnaces of Consett are not rigorously comparable with the three others. The ores treated are richer-a mixtare of hematites and calcined Cleveland oxides; and, above all, the pig-iron is cooler, so to speak-it is Nos. 4 and 5, and not Nos. 3 and 4, like those of Clarence and Ormesby. On this account we should calculate for Consett furnaces rather less than 330 and 550 calories for the caloric absorbed by the fusion of pig and slags. This circumstance explains the relatively feeble amount, found by difference, for the caloric lost by the walls, etc., of the furnace at Consett. Having mentioned this, let us now compare the two furnaces of Clarence, which differ from each other only in capacity and in height, whilst they are charged with exactly the same ores, fluxes, and coke, and with blast at the same temperature, and yield pig-iron of the same quality. If the consumption be different, it must chiefly arise from this difference in capacity and in height in the two furnaces. It is necessary to remark, however, that the section of the furnace of 1866\is more tapering than that of 185a3(figs. 2 and 6). For very different heights, the waist of the large furnace is 6 inches more than that of the small one. The distribution of the reducing gases, and consequently the reduction itself, will be less uniform in the small furnace, and this circumstance alone may involve a less economical working. Nevertheless, we know by the general experience of blast furnaces that this difference of section cannot have any great influence if the mode of charging be suited to the section, which doubtless is the case in Clarence works. The descent of the charges is slower in the large furnace. 80 STUDIES OF BLAST FURNACES. The internal capacity is 300 cubic feet per ton of pig yielded, whereas it is only 195 cubic feet in the small. But this circumstance alone cannot explain the remarkable difference in consumption in the two furnaces. In the greater number of old blast furnaces in Britain and on the Continent, the internal capacity does not exceed 175 to 210 cubic feet, and yet the consumption is often less than in these Cleveland furnaces; and besides, as remarked in ~ 2, the most modern furnaces of Cleveland, which give 350, 420, and even 500 cubic feet capacity per ton of yield, consume no less-the temperature of blast being the same-than the furnaces of smaller capacity, provided the height of these furnaces be suited to the nature of the ores treated, and the temperature of the blast. We have only to consult the numbers referring to Consett furnaces to be convinced that even with heights of 52 feet, and capacities less than 175 cubic feet per ton of yield, we may, with suitable ores, have a very small consumption of fuel; and we therefore already conclude that it would be very rash to assert, in any general terms, that, in all circumstances, blast furnaces of great height and great capacity are necessarily more economical of fuel than those of smaller dimensions. That which first strikes us, in comparing the two blast furnaces of Clarence, is the difference of temperature of the gases, 4520 in the small, against 332~ in the large furnace. Then comes the difference in the ratio CO2 which is 0'387 in CO-' the small, and 0'6865 in the large. This low value of m in the small furnace indicates an unfavorable combustion of carbon; that is, an abundant formation of CO at the expense of CO2 due to the reduction. STUDIES OF BLAST FURNACES. 81 We see, in fact, that each lb. of carbon burned produces 3854 calories in the large furnace, and only 3245 calories in the small. Difference 609 calories. We have found, above all, a great difference in the carbon burned in the zone of reduction: 0'058 per lb. of iron in the large furnace, and 041245 in the small one; a difference which shows that the small furnace is much further from the ideal working than the large one. In reality, the largefurnace consumes per lb. of pig yielded, 1*'020 carbon, of which 0990 is burned,' 0'030 is taken up by the iron. The smallfurnace consumes 1lb'318 carbon, of which 1'288 is burned, 0'030 taken by the iron. Diff. 0'298 in favor of the large furnace. The synoptical table shows, besides per lb. of pig yielded, Total caloric received by the smallfurnace. 4935 cal. Do. do. large furnace. 4418 Difference.... 517 cal. And this excess is supplied partly by the hot blast, partly by combustion, properly so called. Notwithstanding the equality of temperature, the blast carries in more caloric into the small than into the large furnace; because, as it consumes more fuel, it requires more blast. The small furnace receives from the hot blast. 755 cal. The large....... 602 Difference.. 153 cal. 6 82 STUDIES OF BLAST FURNACES. And, on the other hand, the total caloric of combustion is in the small furnace. 4180 cal. in the large........ 3168 Difference.... 364 cal. But what especially characterizes the working of the two furnaces is, that in the higher furnace the caloric directly generated in the region of reduction is greater than in the lower furnace; and, on the other hand, it is the lower furnace which receives most caloric near the twyres. The table gives the following quantities:The zone of reduction of the high furnace receives 1511 cal. Do. do. low furnace receives 1303 Difference.... 208 cal. Zone of fusion of the low furnace... 3632 cal. Do. do. high furnace... 2907 Difference on other side. 725 cal. But it is precisely this greater amount of caloric, developed in the zone of reduction, which is the whole advantage of high blast furnaces. In fact, the excess-208 calories-to the profit of the upper region of the large furnace is in no way derived from a greater proportion of solid carbon burned in this region. We see, on the contrary, that the carbon consumed in the zone of reduction is only 01b'058 in the high furnace, whilst it amounts to 01b'1245 in the low. But instead of solid carbon, CO is burned in the zone of reduction of the large furnace. If we refer back to ~~ 16 and 17, we find that, per lb. of pig, the quantities of CO transformed to CO02 are Olb'414 in the small, and - x 0'244 -= 0b 569 in -w STUDIES OF BLAST FURNACES. 83 the large; and the caloric developed in these upper regions is given in the following statement:In the Large Furnace. In the Small Furnace. By the carbon burned 141 calories 308 calories. By the CO burned 1367 ".. 995 " Total 1511 calories. 1303 calories. Thus, as already remarked, the large furnace approaches much more nearly to the ideal working than the small one. Less solid carbon is burned, and more CO, and this difference in working is expressed by the difference in the values 0'387 and 0'6865 of the ratio -- of the escaping gases. Whilst CO the gases of the large furnace contain, per lb. of pig, 11b'195 of C02 for lib -740 of CO, those of the small contain 1'002 of C02 for 2'591 of CO. Let us now examine what becomes of the caloric received in the two furnaces. We should find in the products, the excess of 517 calories received by the small furnace. The gases carry off in the form of sensible heat, 923 calories in the small furnace, and only 545 calories in the large furnace. Difference 378 calories. On the other hand, the fusion of the slags, and the decomposition of the limestone, require more caloric in the small furnace, because the excess of coke involves an excess of cinder, which, in its turn, requires more lime to flux it. We have, on this account, 1344 calories in the small furnace, 1212 calories in the large furnace. Difference 132 calories. 84 STUDIES OF BLAST FURNACES. The sum of these two differences is 510 calories, leaving only 7 calories of the 517 to account for, and this may well be looked for in the losses by radiation, etc., estimated above by difference.* But these 517 calories only represent a feeble proportion of the consumption of the two blast furnaces, that corresponding to the sensible heat. There is another much more important, which is indicated by greater proportion of CO in the gases escaping. The gases of the small furnace contain, per lb. of pig, 2lb'591 — lb *740 = Olb'851 more oxide of carbon (CO) than those of the large furnace, which is a difference of calorific power = 0851 x 2403 = 2045 calories. If we add to this the 517 calories of sensible heat, we have 2562 calories more received by the small furnace. Of this total, 153 calories come from the hot blast.'. 2562 - 153 = 2408 calories result from the excess of carbon burned; and 2409 the weight of the carbon = -08 Olb'298, which is pre8080 - cisely the difference of consumption of the two furnaces. We have now analyzed the differences of production and consumption of caloric in the two furnaces. Let us now endeavor to discover the cause of these differences. In the first place, the descent of the charges is much slower in the large furnace. The ore in it does not so soon reach the region where the temperature is sufficiently high to determine the transformation of the C02 by the solid carbon of the coke. Quite at the mouth of the furnace the temperature of the gases is higher in the small than in the large furnace* The walls of the small furnace, though less in surface, are hotter at top, for the gases have a higher temperature. STUDIES OiF BLAST FURNACES. 85 452~ instead of 332~; and, starting from thence, the temperature must necessarily increase so much the more rapidly, all else being equal, as the tunnel or mouth is nearer the zone of fusion. Mr. Bell found in the 48 feet high furnace, A cherry red, at... 97 feet from tunnel. A bright red (800~ to 9000), at. 15'7 Temperature of melting copper, at 27'0 " On the other hand, in the furnace 80 feet high, the bright red was found only at 26 feet below the tunnel, and the point of fusion of copper (1000~ to 12000) 53 feet from tunnel-head. Thus, in the upper part of the large furnace, there is a much more extensive zone in which reduction may go on, as in the ideal working, under the action of CO alone, without any consumption of solid carbon. This is the whole secret of the superiority of the large furnace. For one thing, the gases leave the furnace at a lower temperature, their sensible heat is better utilized, and then, there is a larger proportion of CO2 formed, which has the great advantage of consuming little solid carbon in the zone of reduction, whilst developing much caloric by the combustion of CO. But have we the right to conclude from this, that, in a furnace of given dimensions, the consumption will necessarily be so much the less, the slower the charges descend; or, in other words, that by increasing the height and capacity of the furnaces, we shall always effect more economical working? Is there not, under this double relation of dimension and yield, some limit? Is there not, as indicated in ~ 2, a certain rapidity and mean volume giving a maximrurn of advantages, a sort ofjuste milieu, which cannot be passed with impunity? 86 STUDIES OF BLAST FURNACES. It is worth trying to get at the bottom of this question-and first let us examine the case of the small furnaces. What does practical experience say as to the consequences of a very slow descent of the charges. ~ 22. Influence of extra-slow working.-Mr. Bell had six blast furnaces at Clarence Works of 48 feet in height, and 6000 cubic feet capacity. The mean of a month's working gave 1'375 tons coke consumed per ton, when the daily yield was 35 tons. This was the normal working of the furnaces. As an experiment, less and less blast was supplied, which gradually reduced the yield; but the consumption is thus recorded, with a yield of 31'3 tons, the consumption was 1'449 tons. " 29-4 " " 1'553 " 26,06 " " 1'717 " that is to say, increased consumption by lowering the speed of descent of the charges or rate of working.* This example would not however be conclusive; for even at 26'6 tons per day, the working is not very slow, as for each ton there is only 228 cubic feet of internal capacity. The following, however, is, in my opinion, a more salient fact. I shall refer to the enormous consumption found by Ebelmen in 1865 in the two small coke furnaces of PontEv6que and of Vienne in the Isbre.t At Pont-Eveque a blast furnace of 36 feet high and 1250 cubic feet capacity, produced only 3'6 tons in 24 hours of white forge iron with a consumption of two tons of coke per ton. This was an extra-slow working, for the internal capacity was 350 cubic feet per ton of white forge pig. * See Bell, sect. xxxii. p. 215. t Annales des Mines, 4th series. tom. v. STUDIES OF BLAST FURNACES. 87 At Vienne, a blast furnace of 33 feet high and 1200 cubic feet capacity yielded 4 tons per day of gray foundry iron, consuming 2'850 tons of coke! In this latter case, however, the working was not so far from the usual working, for the capacity per ton was 310 c. ft. The enormous consumption arose chiefly from the want of height. Ebelmen was struck by the exaggeration of these figures, but instead of looking for the true cause, he contented himself by drawing the general conclusion, that blastfurnaces working with coke consume twice as much carbon as those working with charcoal, a perfectly erroneous conclusion.* By reason of the more basic character of the slags, the pig made by coke may require a slight excess of carbon, all being equal. For the great porosity of the charcoal favors its combustion by C02 in the upper region of the furnace.t What we know positively is, that the large consumption in the small furnaces of Pont-Eveque and Vienne arises both from their want of height and the slowness of the descent of the charges. Since 1845 all the furnaces of the Rhone Valley have been carried to heights of 50 and 55 feet; and now the yield is so increased that the internal capacity per ton is not more than 175 to 210 cubic feet; and the consumption is reduced to 1'100 to 1'200 ton of coke per ton of forge pig, when the coke is of good quality, with not more than 10 to 12 per cent. of cinder, etc. It appears to me then to be ascertained practically that not only a want of height, but also an extra-slow working, increases the consumption. And theory is in perfect agreement with experience on this head. * See Note III. Appendix. f Note IV. Appendix. 88 STUDIES OF BLAST FURNACES. Whatever be the progress of descent of the chargeswhether fast or slow, it is quite evident that their temperature will increase the more rapidly as the height of the furnace is less. Under these conditions, the ore, very little reduced, reaches the zone where the heat is sufficient to burn carbon by the C02.' Consequently, the consumption must always be great in low furnaces. But there are two extreme cases which would even increase this evil. If the descent is too rapid, in which case the ascending gaseous current has an excess of speed as well as the descending solid current, the oxide of carbon (CO) has not the time indispensable for effecting reduction in the upper part of the furnace. If, on the other hand, the descent be too slow, the carbonic acid (C02), remaining much longer amongst the carbon, will from that circumstance be transformed in larger proportions to CO. In both cases we diverge from the ideal working, we consume more carbon, and we find a less proportion of C02 in the gases.* Consequently, it is quite evident that between these two extremes, there must be for each blast furnace, a mean speed of working for which the consumption will be a minimum.t ~ 23. Influence of great height and capacity. —Let us now consider the immense modern furnaces of Cleveland. Their * The analyses of Ebelmen give a value of 0'4 for CO in the blast furnace of Pont-Eveque, and as the furnace of Vienne gave this value = 0'721, we conclude that the samples did not represent a mean of the currents escaping. t I do not pretend, be it understood, that this theoretical minimnem will always be the most favorable practical working. For reducing the general expenses, it may be advantageous to force production at the expense of consumption of fuel, though very rarely. STUDIES OF BLAST FURNACES. 89 working is relatively slow, for each ton of yield takes 280, 350, and even 420 to 440 cubic feet of capacity. This slow descent of materials may to a certain extent offer the same inconveniences in these large furnaces as in the small. The CO2 has time to reform CO, although, owing to the more gradual increase of temperature in the upper region of the large furnaces, this reaction of carbon on CO2 is much less energetic than in the furnaces of small height. But it is pretty certain that here again there is ajuste milieu giving a minimum consumption. But it is evident that in reference to the height of furnaces it must be limited by the physical qualities of the ore and combustible. If these are small and friable, if they crush or go together under their own weight, it is not possible to exceed a certain height on account of the resistance offered to the passage of the blast, and the uniform ascent of the gases. And if the height be thus limited, it will be the same with the capacity of the furnace. It is only by increasing the diameter for a given height that the capacity can be increased, and this would render the section too stumpy, and consequently, the distribution of the gases irregular and the reduction of the ores partial. In a word, all the conditions of working would be less favorable. We cannot therefore give excess of capacity any more than we can excess of height. Besides, if the waist of the furnace be large, and the distribution of the currents unequal, this latter inconvenience must be remedied by a slower working. This explains why the monster furnaces of Cleveland have for each ton yielded 300 to 400 cubic feet of 90 STUDIES OF BLAST FURNACES. capacity, and why also, as soon as it is attempted to work faster, they work less regularly and consume more coke. We shall now show by some examples that blast furnaces of dimensions beyond certain limits, do not in reality offer any advantages. Take for instance the third furnace mentioned in our table, ~ 21, that of Ormesby of 1867. It has a height of 76 feet with a capacity of 20,500 cubic feet. The section (fig. 8) compared with that of Clarence of 1866 (fig. 6) is relatively stumpy and swelled out at the waist. Well, notwithstanding its capacity, its almost double yield, it consumes no less fuel than the other, for identically the same ore and the same pig-iron. It gives 01b'987 carbon per lb. of pig-iron compared to O0b'990, and that notwithstanding a different temperature of blast of 295~ (7800 - 4850); that is, we have the same consumption, though the one receives 311 calories more by the blast than the other. This clearly indicates a less favorable working, and this is proved by all the figures of the synoptical table. The value of the ratio 002-= m is less: 0'542 against 0'6865. The carbon burned in the zone of reduction is greater in amount: 0lb *105 instead of 0'058. The caloric developed per lb. of carbon is less: 3593 at Ormesby for 3854 calories at Clarence. The gases leave the furnace at a higher temperature, 412~ against 332~, and thus the sensible caloric carried off by the gases is 646 calories against 545 at Clarence. The caloric developed in the zone of reduction is less, notwithstanding the excess of carbon burned, 1365 instead of 1511 calories; and finally, although the consumption is almost identical, the total caloric is less in the Ormesby furnace, 3546 against 3816 calories, from which we may conclude STUDIES OF BLAST EURNACES. 91 that if the higher temperature of blast had not been applied the consumption would have been by so much increased. Thus it seems demonstrated that the large furnace of Ormesby works less economically than that of Clarence Works. This might be attributed to the distended section of the Ormesby furnace. But this section is itself a consequence of the exaggerated capacity, so that we are forced to the conclusion that beyond a certain limit the enlargement of blast furnaces may not only be no advantage, but may become prejudicial. This conclusion is further proved by the following facts, of which the elements are given in Mr. Bell's paper, 32d and 33d sections: This distinguished and able iron-master has at Clarence Works several blast furnaces, all of 80 feet in height, but the capacities of which are respectively 11,500, 15,500, and 25,500 cubic feet (~ 2). But he has been unable to fin.d any appreciable difference between the results furnished by these three types; or rather it is that of the smallest capacity-11,500 cubic feet-the section of which is more tapering, which appears to work best; for it is this which approaches the nearest to the ideal working. The proportions of m are as follows:Several Furnaces of 11,500 c. ft. Furnace of 15,500 c. ft. Furnace of 25,500 c. ft. m =0-698 mn - 0-627 n = 0'560 m - 0'637 m -= 0'686 Mean = 0670' Mr. Ed. Williams, who manages the Eston Works for Messrs. Bolckow & Vaughan, with furnaces of 15,000, 20,000, 92 STUDIES OF BLAST FURNACES. and 27,000 cubic feet capacity, all charged with the same charges, and of the uniform height of 95 feet (figs. 7 and 9), asserts, on the other hand, that he cannot find any advantage in economy or otherwise in the large furnaces. His long experience has convinced him that beyond the limit of 11,000 to 12,000 cubic feet capacity, the large furnaces of Cleveland really offer no advantage in economy of fuel consumed. It is also to be observed that the blast furnaces are 15 feet higher than the Clarence furnaces, and yet they burn no less coke, and the temperature of the escaping gases is not lower. And now, a last remark on the large furnaces of Clarence Works and of Eston. In ~ 2 the three types of Clarence and the two huge furnaces of Eston (figs. 7 and 9) of 15,000 and 27,000 cubic feet capacity have been alluded to. These furnaces consume the same weight of coke per ton of pig yielded, 1'125 ton, but this equality is in reality obtained by the much slower working of the large furnaces, which require 420 to 490 cubic feet of capacity per ton of yield in place of 280 to 320 cubic feet. If therefore the large furnaces were made to yield proportionally as much as the smaller furnaces, the consumption of fuel would inevitably be greater, and therefore the working of the monster furnaces is in truth less advantageous. We cannot escape from this alternative, less production per cubic foot of capacity, or greater consumption of fuel. This conclusion comes out more strongly from comparison of the two furnaces at Ferryhill already mentioned in ~ 2. The one measures 82 feet high, and 16,000 capacity. The other " 104 " 30,500 " The first takes 310 c. ft. capacity, the second 420 c. ft. But, notwithstanding the great difference in height, the STUDIES OF BLAST FURNACES. 913 escaping gases have within 6~ the same temperature in the 104 feet as in the 82 (191~ and 1970), and the consumption of fuel is as nearly as possible the same in the two-1000 tons in the high furnace, and 1025 in the other.* What is the cause to which we are to attribute this apparent anomaly in blast furnaces in which the gases do not vary in temperature after a certain height, which appears to be from 75 to 80 feet? It is an important question. ~ 24. Beyond a certain height the temperature of the escaping gases does not diminish by reason of the dissociation of the oxide of carbon.-We know that the gaseous current of blast furnaces, which at first are composed only of CO and N, become mixed in increasing quantities as they ascend with CO2, and also with watery vapor when the ores and combustibles are moist, or chemically hydrated. The reducing action of the CO is thus partially neutralized in the upper regions of blast furnaces, and we know that certain mixtures of CO2, CO, and HIO have no action on the oxide of iron. Thus M. Debray has proved that the peroxide is simply transformed at intense red heat to protoxide by a mixture of equal volumes of CO anld C02, and that, on the other hand, this mixture converts metallic iron to this same degree of oxidation. Mr. Bell has verified this double reaction; but this mixture of equal volumes corresponds in weight to CO02 1'829 m = CO = 0967 =1581 * In one of the last numbers of the Journal of the Iron and Steel Institute, that of November 1871, Mr. Bell, recurring to the same subject, thus sums up his conclusions as to the working of the Cleveland furnaces: "After a certain capacity, 15,000 c. ft., for example, the escaping gases are as cool and as rich in CO2 as those of furnaces of double this capacity" (p. 391). From discussions of 1ir. Samuelson's account of two monster furncaces, read before the Institute of Civil Engineers. 94 STUDIES OF BLAST FURNACES. Wrheinever, therefore, the CO2 reaches this proportion, reduction cannot go further than the protoxide, and if the current of gas contains steam as well, reduction would reach its limits even before this proportion, m = 1'581, was reached. Besides, there is a certain time required-a prolonged action of the two gases-to reduce ores in small pieces so long as their temperature is not very high. But the ores remain only a few hours in the upper regions of the furnaces; consequently they will be little modified by the gases as soon as CO02 abounds. Thus Mr. Bell has proved that in the Cleveland furnaces, for which the value of m varies between 0'50 and 0'70, reduction almost ceases towards the top of the furnace. At the temperature of melting zinc (about 417~) when the gases contain 31 volumes of C02 to 100 CO, which corresponds to m = 0'49, it requires 5 hours to carry off 1'9 % of the oxygen contained, and 10- (" " 2.9 7 " "" * And when the gases are composed of 50 volumes of CO2100 of CO —which gives m = 0'79, it takes 59 hours to carry 0'9 % of the oxygen on the ores. We thus see that even when the gases are dry and hot, as in the Cleveland district, reduction at the level of the tunnel is insignificant, and it must therefore be still less when the ores are hydrates or carbonates. And indeed this has been recognized by MM. Ebelmen and Tunner long since. In the experiments at Eisenerz, M. Tunner ascertained that reducCO2 tion commences when the ratio of C _ - 2, but that metallic COSection 33 of Mr. Bell's work. STUDIES OF BLAST FURNACES. 95 iron does not appear until the ratio descends to 0'70 —about 23 feet below the tunnel-head.* It is however certain that if there were no other chemical reaction in the upper regions of the furnace than the partial reduction of the ores by CO —reduction effected as we know (~ 11) almost without change of temperature-there ought to be some real advantage in increased height of furnace above the point at which the gases still retain a temperature in escaping of 300~ to 400~. B3y such increased height we should inevitably cool the gases more perfectly, and thus utilize more perfectly the caloric produced. But there is another reaction which always takes place in the upper regions of the furnace: this is the dissociation of the carbonic oxide, and it is this transformation of 2 CO into C02 + C which, after a certain limit, prevents the further lowering of the temperature of the gases by any increase of height of thefurnace. Mr. Bell was the first to point out this singular reaction of the ores on the gases of blast furnaces, and since then I have with much care investigated the principal circumstances attending it. The results of this investigation were communicated to the Academy of Sciences in July, 1871, and the memoir has been published in the Recueil des savants etrangers, and in the May number of the Annales de physique et de chimie for 1872. I shall here transcribe the conclusions:1. If we pass CO over iron ore, heated to 300~ to 400~, the oxide of iron is gradually reduced from the surface inwards of each small piece. But from the moment any small portion of the extreme crust of these morsels is brought to the state of metallic iron, the ore cracks in all directions and gets * Memoir published at Leoben in 1859. 96 STUDIES OF BLAST FURNACES. covered with a dust of carbon. This reaction takes place by whatever method the CO is prepared. 2. As the reduction approaches completion the carbon deposit becomes less abundant, and would altogether cease from the moment the oxide of iron (Fe203) is completely reduced, if this absolute reduction could be realized in the conditions under which our experiments were made. But, at all events, this would require a very long time. 3. If we pass CO over metallic iron at the temperature of 300~ to 4000 C., the iron, in like manner, becomes covered with a dust of carbon from the moment that the reducing action of the CO is partially tempered down, whether by the presence of a small proportion of CO2, or by any source of oxygen which could transform any part of CO into CO2. 4. On the other hand, CO, pure and dry, gives off so much the less carbon to the metallic iron, as the iron is itself free of all admixture of oxygen, so that there would be scarcely any reduction at 300~ or 400~, if the experiment could be made with iron absolutely free of any admixture of oxide. 5. The carbon dust which deposits, either on the ores at the time of their reduction, or on the metallic iron when the CO acts together with a small proportion of C02, is a sort of ferruginous carbon-a composition of iron and carbon with 5 % to 7 2 of metallic iron as a maximum. This carbon differs from that of steel, or the hexagonal graphite of gray pig-iron. The ferruginous carbon contains also a small proportion of oxidized iron, chiefly magnetic, the part played by which seems essential in the reaction which determines the deposit of carbon. 6. Carbonic acid acts as an oxidizing agent on iron; but STUDIES OF BLAST FURNACES. 97 at the temperature of 300~ to 400~ the action is not intense. There is only a small quantity produced in variable proportions of Fe203, Fe203 + FeO, and FeO; that is to say, of the peroxide, the magnetic oxide, and the protoxide of iron, and these oxides are never accompanied by a deposit of carbon. 7. The formation of ferruginous carbon is the result of a sort of dissociation of CO. 2C0 is transformed to C02 + C, but this reaction never takes place directly. That it may take place there must be simultaneous presence of metallic iron and protoxide of iron-the metallic iron to fix the carbon, the protoxide to retain for a moment the oxygen. But this passing reoxidation of the protoxide, which resists its final reduction by this very reaction, can only be produced if the reducing action of the CO be partially tempered down by CO02. This, I repeat, is the sine qua non condition of the deposit of carbon. This double reaction is expressed by the formulas3FeO + CO - Fe304 + C (this carbon having been united to the iron), and Fe304 + CO = 3FeO + CO, and so on indefinitely, provided that the CO is always tempered in reductive action by a certain portion of CO2. In one word, CO pure is not dissociated by iron absolutely free from an oxidized element. In the same way, CO02, if it acts alone on iron, does not deposit ferruginous carbon; and lastly, the two gases united, provided CO be in excess, produce an abundance of ferruginous carbon by the sinmultaneous action on metallic iron at the low temperature of 3000 to 4000~. 8. Spathore iron, or the protoxide of iron (FeO), is rapidly 7 98 STUDIES OF BLAST FURNACES. transformed into magnetic oxide under the action of CO2 without any deposit of carbon, whilst CO in the same circumstances rapidly deposits large quantities of ferruginous carbon. 9. If we raise the temperature to a lively red, in those experiments which give ferruginous carbon, the deposit immediately ceases, and, moreover, the carbon already deposited is burned again so long as there is present a sufficient quantity of oxide unreduced. Thus the reactions are in this respect quite different at high temperatures from what they are at temperatures of 300~ to 400~. 10. In reference to the theory of the blast furnace, it may be remarked that the carbon must deposit itself on the ores in the upper regions of the furnace, and that this carbon dust must facilitate the ulterior reduction of the ores, and that of C02, in the middle regions of the furnace. At all events, in consequence of this reaction, the carbon deposited will be burned a second time in the zone of fusion. 11. The dissociation of CO takes place with a development of caloric. For each unit of carbon deposited there is a disengagement of 3134 calories. To the resume of what goes before, I add two observations. The dissociation of CO does not take place when a mixture of equal volumes of CO and C02 are made to act on the oxide of iron, that is when m = 1'581. According to M. Debray's experiments, only FeO is formed in this case, whilst metallic iron is necessary to determine the deposit of carbon dust. If, on the other hand, we have 2 vols. CO to 1 vol. C02, which corresponds to m - -79, then the carbon commences to deposit, for then also metallic iron begins to appear, provided STUDIES OF BLAST FURNACES. 99 of course that the current of gases be sufficiently rapid to carry off, without delay, the C02 formed. My second observation is relative to the disengagement of 3134 calories, due to the deposit of ferruginous carbon. This is the essential point of the phenomenon in question, as regards the temperature of the gases and the limit of height of blast furnaces. The caloric produced by the combustion of 2 C to 2 CO is, as we know, 2 x 2473 = 4946 calories. On the other hand, when the half of 2 C is transformed into CO2, the caloric developed is 8080 calories: therefore the dissociation of 2 CO into C + CO2 unquestionably sets free 8080 - 4946 = 3134 calories. We may therefore conclude that when the escaping gases have a temperature of 300~ to 4000, and such a composition that the ratio m - CO= — 080, there will be not only partial reduction of the ores, but also impregnation and deposit of carbon dust, with a notable disengagement of caloric, from which there results a sort of stationary condition without any further lowering of temperature of the gases, notwithstanding greater height given to furnace. But what actually takes place is this:In the upper part of the furnaces, two different reactions take place at the same time. On the one hand, ore is reduced by CO giving CO2 without sensible change of temperature. On the other hand, 2 CO is transformed to C + CO2, with a production of 3136 calories. The carbon C resulting from this dissociation is restored to the charge in the shape of carbon dust. It descends with the charge, and then reforms CO in the lower hotter regions. The CO thus reproduced ascends again, and is dissociated in its turn into (I C + I C02). 100 STUDIES OF BLAST FURNACES. And the same reaction is renewed indefinitely, and thus the sum of the reactions is just as if the 2 CO had been directly transformed into 2 C02 by the oxygen of the ores; that is, as if the reduction took place, as assumed in the ideal working, by the action of CO without consumption of solid carbon, and consequently without sensible variation of temperature. The dissociation of the CO brings the ordinary good working nearly up to the ideal working, and consequently whatever favors this dissociation will reduce the consumption of fuel; and hence we may conclude increase of height of furnaces would lead to a gradual diminution of consumption, the extreme limit of which would be the ideal working of the furnace. But, in fact, this could not be realized. In the first place, the height of the furnaces is limited by the increasing resistance of the charges to the passage of the blast. Again, although the sum total of the caloric disengaged depends solely on the value of the ratio m for a given consumption, its distribution will be chiefly regulated by the manner of production of CO2. When CO2 comes from the dissociation of 2 CO, there is production of caloric in the upper region of the furnace, whilst there would be absorption in the middle region where the carbon desposited is transformed into CO by the oxygen of the ore. It is true that there is only a displacement of caloric, but the gases thus reheated in the upper part of the furnace will, from want of time, yield less caloric to the cold elements of the charges than if their temperature had been raised in the middle regions by the simple oxidation of CO to CO2 by the ores. Raising the height of furnaces tends to a sort of constant STUDIES OF BLAST FURNACES. 101 calorific state by favoring the dissociation of CO, but after this there can be no sensible advantage. I shall only add one more observation. All that I have said applies only to blast furnaces in which calcined anhydrous ores alone are charged, as in Cleveland. Elsewhere, in the districts of France where hydrated oxides are used, for example, and in districts also where incompletely calcined spathic ores are used, the tunnel-head is much cooler. Thus I have quoted from M. Tunner's memoir the example of Eisenerz, where the metallic iron, and with it the dissociation of CO, does not begin to declare itself till 23 feet below the top. But in furnaces of small height, the charges would get into the highly heated zones in which this reaction ceases again very soon after. Any raising of the height of furnaces, in such cases, might enlarge the zone in which dissociation would take place, and thus lead finally to a certain economy by rendering the gases richer in CO2. But it is evident, for the reasons above given, that there is here again a limit at which real economy becomes insignificant.-En resume — After a certain height has been attained, variable with the ores and the section of the furnaces, there is no longer any advantage in enlarging their capacity. ~ 25. Influence of highly heated blast.-Let us now, in the second place, endeavor to appreciate the influence of variations of the temperature of the blast on the working of the furnace. Let us, for this purpose, compare the two furnaces of Consett, cited in our synoptical table. The dimensions and the section differ very little; the charges are identical; the pig-iron yielded is the same. On the other hand, the temperature of the blast is 4540~5 in the one, and 718~ in the other. The difference in the results 102 STUDIES OF BLAST FURNACES. obtained can therefore only be attributed to the difference of 263~ of temperature. The blast of the one furnace is heated in ordinary cast-metal tubes, that of the other in one of Whitwell's brick stoves. The combustible for heating is, in both cases, the furnace gases. What strikes us at once is, that the escaping gases are colder, the hotter the blast-viz., 4770 for the 4540 blast, against 248~ for the 718~ blast. This is indeed a well-known, well-ascertained result wherever hot-blast is substituted for cold. The hot-blast cools the top of the furnace, because a larger proportion of the caloric received is due to the blast. Combustion furnishes less gas, and this is better cooled in ascending through the same mass of solid materials. The differences between the two Consett furnaces are great in these points of view. The furnace with highly heated blast receives per lb. of iron yielded, only. 31b'751 blast, and gives off only..... 5b 161 of gases, whilst the furnace with blast at ordinary temperature of hot blast, receives. 51b'071 of blast, and gives off.... 61b'706 of gases. The caloric of combustion in the zone of twyres is 1672 calories only in the first case, against 2249 calories in the second, and this enormous difference is only compensated in a very small degree by the caloric carried in by the blast, which is 643 calories against 551 calories-a difference of 92 calories. Again, the zone of fusion of the furnace with ordinary hot blast, receives, notwithstanding this, an excess of caloric of 2800 - 2315 = 485 calories, STUDIES OF BLAST FURNACES. 103 and the difference is still greater in the total caloric received by the two furnaces; this is 4192- 3654 = 538 calories. But this excess of caloric received by the furnace with ordinary hot blast is accounted for almost wholly by the caloric carried off by the gases, which amounts to 758 calories in the first furnace, against 303 calories carried off by the gases of furnace with highly heated blast. Difference, 455 calories. The advantages of the superheated blast are manifested by the higher ratio of C- m, which is 0'623, instead of 0'502. The carbon burned is better utilized; and this difference certainly arises from the lower temperature of the zone of reduction tending to determine a more active dissociation of the CO. Thus, the use of superheated blast at Consett gives an economy of lib *0055 - 0lb'789 = Olb'2165 carbon (pure) per lb. of iron yielded-an economy of which only a very small amount arises from the caloric carried in directly by the superheated blast.* It is chiefly due to more useful distribution of the caloric which effects a more energetic cooling of the gases, and to the earlier combustion of the carbon developing 3816 calories per lb. in the case of superheated blast, and 3621 calories in the case of ordinary hot-blast. Thus, there are considerable advantages obtained by the superheating of the blasts to the extent we have been * The excess of caloric carried in by the superheated blast is 92 calories, and this replaces only 924 0037 of carbon burned at the twyres. 104 STUDIES OF BLAST FURNACES. examining, and that without any alteration in the nature of the products obtained. when working with ordinary ores. It remains to be seen whether, in reference to this question, there are not other limits besides practical possibility. Might we without prejudice heat the blast to 800~, 900~, 10000, etc., and will each increment of temperature be accompanied by an equivalent economy in the carbon consumed? Experience alone can solve this problem. But from the facts we have collected, we can, to a certain extent, ascertain what would be the result of further heating the blast. As the temperature of the blast increases, the temperature at the tunnel-head decreases. This is a fact well ascertained, and the Consett experience proves it once more. The hot blast acts, in this respect, like an increased height of furnace; but the dissociation of the CO puts a limit to this cooling. According to the results given by the highest furnace of Cleveland, it appears that the temperature of the escaping gases does not descend below 200~ C. I speak always, of course, of furnaces supplied with calcined Cleveland ores, and not of furnaces smelting hydrated or carbonated ores. At the highest furnace of Cleveland, that of Ferryhill of 104 feet high, the gases have still a temperature of 191~ C.; and yet in these works they use in the charges ores which travel 40 miles after their calcination, which in ordinary circumstances must give rise to the absorption of a certain amount of humidity. We may therefore admit as the lower limit, in Cleveland conditions, a temperature of 200~ C. at the tunnel-head. Another consequence of the use of highly heated blast, as of the increased height of the furnace, is the gradual increase STUDIES OF BLAST FURNACES. 105 in the value of m. We approximate to the ideal working, and we have seen that at Consett the ratio m rises from 0'502 to 0'623. As the blast is more heated the combustion of carbon at the twyres decreases, and therefore the mass of CO produced above this point diminishes. But, as the oxygen of the ore is constant, there must take place one of two things-either the CO2 will go on increasing, and the limit at which the CO dissociates will soon be reached, which corresponds to m = 0-80, and soon after the ideal working would be reached, where m = 1'217 (~ 5); or the excess of C02 in the region of reduction will act on the solid carbon, and, while the consumption near the twyres will decrease, it will increase in the region of reduction-or, rather, in general, the two effects will be simultaneous; —the ratio m will be seen to increase concurrently with quantity of carbon burned in the region of reduction. This is exactly what takes place at Consett. In comparing the furnace with ordinary hot blast and that with superheated blast, we see that not only m passes from 0-502 to 0'623. but the carbon burned in the zone of reduction rises from 0'096 to 0'113. Now, starting from the consumption at Consett, we can easily calculate, for quantities of carbon burned at the twyres successively decreasing, and values of m successively increasing, the temperatures that must be given to the blast, and also the carbon burned in the zone of reduction. I shall first assume a constant value of m = 0'623, the figure found for Consett furnace working with blast at 718~ C. We have seen that in this case the carbon burned at the level of the twyres is 0lb'789 - 0113 = Ob 676. Let us suppose this weight reduced successively to 0'650 and 0'600. Let us calculate the carbon burned in the zone of reduction 106 STUDIES OF BLAST FURNACES. under these conditions, and let us determine what must be the temperature of the blast to get the caloric necessary for the working of the furnace. We know the total oxygen supplied to the gases of the furnace. It is composed of the oxygen derived from the charge, and of that carried in by the blast. But this sum should equal the total oxygen of the carbonic oxide and the 4 8 carbonic acid of the gases, that is to say, = y + my, according to the notation of ~ 7. This ratio,will allow of our determining the values of y and my, and consequently the total carbon contained in the gases. The oxygen of the charge is given by formula (3.) ~ 7, d =8 b1 (3'03) but it is well to remark that the term, (3'03), which represents the oxygen of the ore, is composed of two parts, the oxygen abandoned in the zone of reduction = a (2'82) 01b'403, and the oxygen taken up near the twyres by the direct action of the carbon - 1 (021) = 0 030.* The oxygen carried in by the blast is determined by the carbon burned near the twyres. But one of carbon combines with 4 of oxygen to form CO: if then the weight of carbon be 0'650, we shall have for corresponding oxygen A x 0'650 = 0'867, of which 0'030 is furnished by the charge, and 0'837 by the blast. Let us apply these principles to the furnaces of Consett No. 4 (~ 20), in which the carbon of the limestone b = 00485 we shall have for total oxygen, * See ~ 7, p. 36 ante. STUDIES OF BLAST FURNACES. 107 01b *867 + 01b.403 + 8 (0lb'0485)=- lb.399, and consequently we have the equation, 4 8 7 + 4 nzy = 1lb 399, or, as m = 0'623, (7 = 81-1 x 0.623) y= 11b 399 77 x 1.399 And hence CO or y =- 144 365 44 + 56 x 0 =623 CO2 = my- 0'623 x 0'625- 0'850 But the CO or y contains. 3 x 1365 = 0585 carbon. And the CO2 or my ". 3x 0850 = 0232 " 11 Xor the total carbon of the gases, p,.. 0817 " and as the carbon burned at the twyre and that supplied by the limestone are - 0'650 + 0.0485..... 06985 " we have for the carbon burned in the zone of reduction..... 01185" And now from the total carbon we can deduce the caloric of combustion: The CO develops... 0'585 x 2473 = 1446 cal. The C02 gives. (0'232 - 00485) x 8080 = 1483 Total caloric of combustion 2929 cal. Let us admit that the caloric absorbed is the same as was ascertained for No. 4 furnace at Consett (~ 20), i. e. 3654 cals., the blast must therefore carry in 725 cals. instead of 643. But in reality the caloric absorbed will be less, because the weight of the gases will be less, and besides, their temperature 108 STUDIES OF BLAST FURNACES. would be somewhat lowered. We should find for this difference a maximum value, by supposing that we get to the limit of cooling at 200~, above indicated. The weight of the gases is as follows:my or CO2.. = 0850 y or CO... 1'365 3'33 x 0'837 x 0'9767- 2722 iThe oxygen x of blast XN333 x I837 x 09767= 22 being = 0'837 Weight of dry air. 4*937 Water from coke.. 0022 Weight of moist gases. 4'959 instead of 5'161 of ~ 20. Therefore the caloric carried off by the gases will be 41b 959 x 2000 x 0'237 = 235 calories, instead of 303 calories found in ~ 20. The caloric absorbed or necessary will therefore be decreased by 68 calories, and thus reduced from 3654 to 3586. Although in fact the gases would escape at a somewhat higher temperature than 2000, let us admit these numbers. The blast would have to furnish at least 3586 - 2929 = 657 calories, and as the weight of blast is, according to the formulas of ~ 7, 0'857 x 4'33 x 0'9828 = 31b'562, we then have for the minimum temperature of the blast, 657 657 3'562 x 0'239 0-851 Let us now calculate the caloric developed in the zone of reduction. It is equal to the total caloric of combustion STUDIES OF BLAST FURNACES. 109 minus the caloric developed near the twyres by the combustion of 0'650 of carbon, which is. 0'650 x 2473 = 1607 cals. and there therefore remains for the caloric of the zone of reduction...... 1322 Total calories, as above 2929 But, according to the synoptical table of ~ 21, the caloric of combustion in the zone of reduction of No. 4 Consett furnace is 1339 calories. Thus, as has been already remarked, as the temperature of the blast increases the calorie of combustion diminishes in the zone of reduction, and that notwithstanding the increase of the carbon consumed in this region, which rises in this case from 0'113 to 041185. Let us now go through the same calculations for the case in which the carbon consumed near the twyres is reduced to 01b'600. 4 The oxygen corresponding = x 0'600 = 0'800, and as 0'030 is furnished by the charge, there remains for the blast 0'770, and hence the total oxygen will be, 0'800 + 0'403 + 8 (0'0485) 1 lb 332, which gives 77 x 1'332 CO = y- 778 332 1'300 containing carbon, 0'557 and C02= my = 1'300 x 0'623 = 0'810,... 0221 Total carbon of gases, 0'778 Carbon burned at twyres and derived from limestone, 0'6485 Therefore carbon burned in zone of reduction, 0'1295 110 STUDIES OF BLAST FURNACES. The caloric of combustion is, according to this, For CO 0'557 x 2473..... 1377 cals. CO2 (0'221 —0'0485) x 8080 = 0'1725 x 8080 = 1394 Total, 2771 cals. To find the sum of caloric necessary for the furnace, we must calculate the caloric carried off by the gases, admitting as above that they are cooled down to the extreme limit of 200~ C. The gases are composed ofmy = C02....= 0810 y- CO..... 1'300 N = 3'33 x 0'770 x 0'9767. = 2504 by formulas of ~ 7. Weight of dry gases. = 4'614 Water from coke... = 0'021 Weight of moist gases. = 4'635 and hence caloric carried off by gases 4'635 x 2000 x 0'237 = 220 calories. instead of 303 of ~ 20. The necessary amount of caloric is thus reduced by 83 calories, that is, to 3571. The blast has therefore to furnish 3571 - 2771 = 800 calories. But the weight of blast is, according to ~ 7, 0'770 x 4'33 x 0'9828 = 3'277, and hence for temperature of blast, 800 800 -- ---- =1022~ 3'277 x 0'239 0'783 And now let us calculate the caloric developed in the zone of reduction. We have, Total caloric of combustion.... 2771 cals. Caloric developed near twyres, 0'600 x 2473. 1484 Therefore caloric developed in zone of reduction 1287 cals. STUDIES OF BLAST FURNACES. 11i Let us now bring together, in a synoptical table, the results found actually at Consett, and the results which we have found by calculation on the hypothesis that m = 0'623 does not vary:Actual Hypothetic Hypothetic Working. Working. Working. Carbon burned at the twyres..bs. 0'676 0'650 0-600 Carbon burned in the zone of reduction " 0'113 0'1185 0'1295 Total carbon consumed, including the l} 0h819 0-7985 0,7595 0'030 taken up by the iron.9 Caloric developed in zone of reduction. cals. 1339 1322 1287 Caloric developed near twyres. " 1672 1607 1484 Total caloric of combustion. 3011 2929 2771 Caloric carried in by blast..643 657 800 Total caloric received or necessary " 3654 3586 3571 Temperature of the gases... deg. 248 200 200 Temperature of blast." 718 772 1022 Weight of blast.. bs. 3751 3-562 3'277 This Table shows that after a certain limit of temperature the advantages of superheated blast become less and less, and this fact is due to several causes: 1. The mass of air diminishes as the temperature increases.* 2. The cooling of the gases of the tunnel-head, at first very rapid, is soon limited by the development of the phenomenon of dissociation of CO. 3d, and lastly. The ratio m, which we have assumed as constant at and above 718~, cannot, in fact, increase above a certain maximum, for reasons already given in detail; and this limits the caloric developed in the zone of reduction. From this it appears certain that although there is great advantage, under the conditions of the Cleveland furnaces, * See Bell, op. cit. 112 STUDIES OF BLAST FURNACES. in raising the temperature of the blast from 400~ to 700~, there is not nearly the same advantage in adding 3000 more, that is, heating the blast to 10000~. It remains now to show that these conclusions would be very little modified even if the ratio m was 0'70, or even 0'80, which is the proportion at which the CO is no longer dissociated. Let us take of the same calculations in the hypothesis of these new values of m, and let us see, in the first place, which changes would be produced on the working of No. 4 Consett furnace, if m passed from 0'623 to 0'70. Carbon burned near the twyres.. - 0676 Oxygen furnished by the blast 4- x 0676- 0030 0871 Total oxide of carbon -x 0-676 + 0 403 + (0 0485)=1*443 and hence 77 x 1'443 110-341 1b.326 with 568 CO or y = —-- c326 arbon = 0-568 44 x 56 x 0'70 832 and CO2 or 1my 1326 x 0'70 =0'928{ wI = 0t253 Therefore total carbon of gases 0'821 Sum of carbon burned at twyres, and in limestone 0'7245 Carbon burned in zone of reduction. 00965 The caloric of combustion is therefore From CO c 0'568 x 2473. = 1405 cals. "4 CO2 = (0'253 —0.0485) x 8080 = 1652 Total. 3057 cals. The gases are composed of my or CO2... 0928 y or CO... 1326 N = 3'33 x 0'871 x 0'97677 = 2'833 (formulas of ~ 7). STUDIES OF BLAST FURNACES. 113 Weight of dry gases. 5087 Water of coke.. 0022 Weight of moist gases. 5109 The temperature of these gases will not much differ from those of the actual working, as their weight is nearly the same, 5b'109 to 5lb'161 (~ 20). The caloric carried off by the gases will hence be 5lb 109 x 248~ x 0'237 = 300 calories instead of 303. The necessary caloric will therefore be decreased by 3 calories, which brings it to.... 3651 cals. And as the caloric of combustion is.. 3057 There remains for the heat of the blast.. 594 cals. But the weight of the moist blast is, according to ~ 20, 31b'751, and hence for the temperature of the blast 594 3 59451 9- 662~ instead of 718~ 3-751 x 0'239 that is to say, any increase in the ratio m admits of a lowering of the temperature of the blast, or it involves, for equal consumption of fuel, a higher temperature of the gases. Let us now calculate the caloric developed in the zone of reduction:We have total caloric of combustion.. 3057 cals. Caloric developed near twyres 0'675 x 2473 = 1672 And hence caloric developed in zone of reduction 1385 cals. We can, in the same manner, calculate all the details for the case of the carbon burned near the twyres being reduced to 0'650 and 0'600. To abridge the matter, a synoptical view only is given in the following Table. It is only necessary to 8 114 STUDIES OF BLAST FURNACES. say that, as in the cases above given, it is assumed that the gases go off with a temperature of only 200~. We then have for the supposition that m _ 0'70:Carbon burned at the twyres... bs. 0'676 0650 0600 Carbon burned in zone of reduction " 0'0965 01035 0'1145 Total carbon consumed, including the 0'030 absorbed by the iron... 08025 0'7835 0'7445 Caloric developed in the zone of reduction cals. 1385 1369 1329 Caloric developed near twyres.. " 1672 1607 1484 Total caloric of combustion 3059 2976 2813 Caloric carried in by blast... cals. 594 609 757 Total caloric necessary 3651 3583 3570 Temperature of the gases. deg. 248 200 200 Temperature of blast. " 672 715 967 Weight of blast.. lbs. 3751 3562 3'277 And now I shall, in like manner, give a synoptical table of the elements of working the Consett furnace, in the hypothesis that the ratio rn could be brought to 0'80, the limit at which dissociation of CO takes place. This case is not yet know to occur in Cleveland, but it is important to have exact notions of the effects of such working. The only uncertainty which attaches to the results is the unknown temperature of the escaping gases. For the high temperature of blast corresponding to the small consumption of 0'650 and 0'600 of carbon at the twyres, it is more than probable that the gases leave the furnace at the limit of 200~. But when the consumption is 0'676 before the twyres, it may happen that the temperature of the gases is higher than this limit, 200~, which would, of course, involve a higher temperature of blast, for from this cause alone the necessary caloric would be greater. The following are the results of calculations on the double hypothesis of m = 0'80, and the temperatue of gases = 200~: STUDIES OF BLAST FURNACES. 115 Carbon burned at the twyres.. lbs. 0'676 0'650 0'600 Carbon burned in zone of reduction. " 00785 0'0865 0-0985 Total carbon, including 0'030 for combination with iron. " 0'7845 0-7665 0-7285 Caloric developed in the zone of reduction. cals. 1442 1428 1384 Caloric developed before twyres.. " 1672 1607 1484 Total caloric.. 3114 3035' 2868 Caloric carried in by blast.. " 477 549 701 Total necessary caloric. 3591 3584 3569 Temperature of gases. deg. 200 200 200 Temperature of blast.. 561 645 895 Weight of blast..... bs.3'51 3'562 3'277 These two last Tables confirm the conclusions drawn from the first. For the same value of the ratio m, the carbon burned in the zone of reduction increases when, by increasing the temperature of the blast, the total consumption, as well as that near the twyres, tends to decrease; and yet the caloric developed in the zone of reduction is so much the less as the blast temperature is higher. If we compare the three Tables with each other, we see that to ascertain the caloric necessary in the furnace, the blast temperature must be so much the higher as m is less. But it is evident that, all other things being equal, it will be more economical to get this necessary caloric by a good design of the furnace than by an overheated blast. In any case, the maximum of economy will be attained by the combination of high temperature of blast and a high value qof the ratio m _C. But this high value of m corresponds with a certain mean height of furnace, as shown in the preceding paragraphs, and presupposes that the working is slower in proportion to the greater capacity of the furnace-that is, from the moment a certain limit is overstepped. 116 STUDIES OF BLAST FURNACES. And now to answer the question proposed at the commencement of this paragraph-whether there is advantage to heat the blast to 800~, 900~, or 10000. We can boldly answer, Yes. For each rise in temperature of the blast there is increased economy, abstraction being made of course of the cost of maintaining and firing stoves for heating the blast. At the same time this economy decreases rapidly with the rise in temperature. The economy arising from each accession of 100~ to temperature of blast is much less from 8000 upwards than from 500~ to 7000, and still less than between 400~ and 500~, and thus in practice it is almost useless to exceed 700~ to 800~. ~ 26. Conclusions.-It is now time to state the conclusions to which we have been successively led by the preceding study of the blast furnaces of Cleveland. 1. The production of blast furnaces beyond the capacity of 7000 cubic feet does not increase in proportion to that capacity (~ 1). 2. To appreciate rightly the working of blast furnaces, it is important to determine by experiment the ratio C0 in the Co escaping gases. By help of this ratio we can not only calculate the true composition of the gases, but also the weights of blast necessary for the furnace. 3. To determine exactly the ratio CO2 it is not sufficient to Co draw off a certain number of samples taken from time to time instantaneously. The gases must be drawn off for several hours, and for this purpose it will be well to have recourse to an apparatus analogous to that used by Mr. Scheurer-Kestner STUDIES OF BLAST FURNACES. 117 in his analysis of the products of combustion of coal under steam boilers (~ 9; Plate, Fig. 13). 4. Once the composition of the gases is known, if we would render an exact account of the working of the blast furnace, we must establish a balance between the caloric received and the caloric expended, and estimate separately the caloric developed in the zone of the twyres, and that which is produced in the zone of reduction (~~ 10 to 15). 5. In the application of these principles to several blast furnaces of Cleveland, we have found that the advantages of very high furnaces over low furnaces, result simply from the lower temperature of the upper parts of the body of the furnace. Reduction goes on more perfectly and completely by the action of CO alone, without intervention of solid carbon. We approach the ideal working, which supposes the solid carbon burned exclusively by the oxygen of the blast. An additional advantage, and more direct, is the less amount of sensible heat in the escaping gases (~ 21). 6. The consumption of blast furnaces depends partly on their yield. The minimum consumption corresponds to a mean speed of descent of the charges, and this varies besides with the height and absolute capacity of the furnaces (~~ 22 and 23). 7. By reason of the dissociation of the CO in the upper region of blast furnaces, the temperature of the escaping gases cannot descend below a certain limit, and on this account there is no advantage from the time this limit is attained in enlarging either the capacity or height of the furnaces (~ 24). A very slow rate of working and an excess of capacity are prejudicial. 8. The caloric carried in by the hot blast replaces advan 118 STUDIES OF BLAST FURNACES. tageously what is developed in the zone of the twyres. The relative economy due to hot blast decreases as the temperature is made higher. In practice there seems to be no real economy after the limit of 700~ to 800~ has been reached. The hot blast tends to raise the ratio C02 and by cooling the upper regions of the furnace it favors reduction without consumption of solid carbon; that is, the ideal working of the apparatus. APPLICATION OF THE NEW METHOD OF ANALYSIS TO A FRENCH BLAST FURNACE. ~ 27. The investigation of which I have just summed up the principal conclusions is composed of two parts:I first showed how, with help of a simple apparatus, we can obtain samples, small in volume, it is true, but representing the exact mean composition of the escaping gases of a blast furnace, and how, by merely determining the ratio of c0o we can, quite sufficiently for practice, approximate not only to the complete composition of these gases, but in a more rigorerosway than by any other method, the weight of the blast consumed in the furnace. I then showed how, with help of the elements thus determined, we can make up the calorific balance of blast furnaces, and thus render a complete account of all the details of its working. By applying these principles to some English blast furnaces, and making use of the analysis made by Mr. Lowthian Bell, I endeavored to solve the important question of the STUDIES OF BLAST FURNACES. 119 maximum height and limit of capacity, and also that of the use of superheated blast. It is quite unnecessary that I should insist on the advantages of such an analytic study of the working of blast furnaces. It is time to quit empirical methods for rational investigation. Uip to the present time the difficulties and complication of processes have stayed progress. The mode of analysis which I propose is simple, and available in every industrial laboratory. Until this mode can be applied by myself and others in France I desire to show by one example how it is possible to ascertain, even without chemical analysis, how nearly the working of a blast furnace approaches or falls short of the ideal working, that is, of the minimum consumption possible. We have seen above how far the old 46 to 56 feet furnaces of Cleveland were from realizing the ideal workings; the gases escaped at a high temperature, and the proportion of carbonic acid in them is small. The ratio C2 rarely attained 0'40. The progressive increase in the height of the furnaces overcame this double disadvantage; but it is quite evident that in cases where the gases are cool, and the ratio of C02 to CO approaches unity, the progressive increase of height is useless, and hence the great importance of determining the ratio CO2 in each particular case. W'e could then determine a priori whether there would be or not an advantage in modifying the dimensions of the furnaces. By these studies abortive trials, such as are alluded to in ~ 2, may be avoidedblast furnaces raised to great heights, and then decapitated and reduced to the old dimensions. 120 STUDIES OF BLAST FURNACES. We have in France numerous coke blast furnaces of ordinary dimensions, the consumption in which is not greater than in the great furnaces of Cleveland, and yet the ores there treated are neither richer nor more fusible than those of the north of England. These furnaces would gain very little in being increased in height, for the gases are now relatively cool and the consumption small, so that a priori we may feel sure that the ratio C-2 is not far from unity. Let us show by an example that even without an analysis, properly so called, it is possible to arrive at an approximate determination of this ratio, and to ascertain up to a certain point if it be possible to improve the working of the furnace. It is, however, quite clear that in any case it would be most useful to be able to confirm these approximations by a direct examination of the gases of the tunnel-head. I take as an example one of the blast furnaces of Pouzin, of the Societe de l'Horme, situated on the borders of the Rhone, between Valence and Mont6limart. The data have reference to 1857 —somewhat old, but the ores, the coke, the consumption, etc., are even now the same. The yield alone is different. In 1857 the yield was only 18 tons; it is now 25 to 30 tons. The section of the furnace is tapering (fig. 12). The height is 55 feet, and the capacity 4000 cubic feet. The blast was heated to 290~, and supplied at pleasure by two or three twyres. The temperature of the gases escaping was 150~. The normal yield was forge pig No. 4. The ore is the red haematite of the Oxford formation, with an argilo-calcareous matrix. Its average composition is represented by the following: STUDIES OF BLAST FURNACES. 121 Peroxide of iron.. 60, with 42 of iron. Clay.... 21 Carbonate of lime.. 15 Water.... 4 100 The various elements of the working of the furnace are put together in the following Table, giving the balance of raw materials and yield. This is the model of such tables used by me for a long time for my lectures at the Zcole des Mines. 122 STUDIES OF BLAST FURENACES. BALANCE OF RAW MATERIAL AND OF YIELD of one of the Blast Furnaces of Pouzin (1857), the pig-iron containing 3 per cent. of carbon, 2 per cent. silicium, 1 per cent. of other foreign matters. Yield. Raw materials per lb. of Distribution of the materials. pig yielded. Pig- Slag. Gas. iron. lbs. Ore... 2-340 Composed of- lbs. C Peroxide of iron, 1-343 { Fe 0940 0403 (0'60) Fe203 1 404 i Peroxide of iron, 0-061 Few/..., 1-404 0.... ( 0-006 (02) clay. Silica and earth Si, etc. 0-030 (0'21) clay. 0-491 See d 003 See ~ 7. i 0.431 undecomposed clay.. 0'431. (0-15) carbon- 5 Lime........ 0196 ateof lime 0351 CO2.......... 0155 (0'04) water, 0'094 Steam..... 0'094 2-340 Flux.. 0-600 CLime2... 0-3. 24 c. _. 02 64 f Carbon. s. Ib. 0'970 0-030.. 0940 Cinder" 0-180.. 0-180 Coke... 1-200 Water." 0050.... 0"050 I Coke... " 1200 Totalw material44 f Giving....... 1000 1198 942 NOTE.-To have the total weight of the gases, we must add to 1-942 the weight of blast supplied. We shall see that this may be valued approximately at 4'875. It is also to be remarked in passing, that when we know the composition of the matrix of the ores, and of the ashes of the coke, we can also, by means of this table, determine a priori the composition of the slags. STUDIES OF BLAST FURNACES. 123 In order now to a at,-hy this Table, the real working of the furnace, we must first make an approximate estimate of the caloric consumed. This is composed (by ~ 10) of four parts, of which two can be determined with sufficient exactness, and the two others only approximately. The first part includes, on the one hand, the caloric absorbed by the reduction, which scarcely varies with the nature of the ores if they be peroxide; and, on the other hand, the caloric possessed by the iron in flowing from the furnace. The caloric of reduction is... 1984 cals. (~ 11). For caloric of fusion for forge iron, No. 4, say 310 Total.. 2294 cals. In the second part, there is first the caloric in the slags. As the ore is fusible, we may put this at 500 calories per lb. of slags, instead of 550, which gives for 1'198 lb. of slag, 599 calories. We have then the caloric taken for decomposition of the limestone, the vaporization of water, and the decomposition of the moisture of the air. It is only this last element which is uncertain, because we do not know the exact weight of the blast. But we may admit, provisionally, as the weight, 4'50 lb., considering what we know of the carbon consumed and the results derived from the Cleveland furnaces. The third part is the caloric carried off by the gases. We know their temperature. As to their weight, it is sufficient to add to the gases from the charges the air of the blast, that is, according to our table, 4'5 + 1'942 = 6'442; and the fourth part is the caloric lost by radiation, etc., from the 124 STUDIES OF BLAST FURNACES. walls of the furnace; and we may admit 300 calories, judging by Mr. Bell's data for Cleveland. Starting from these principles, we shall find for the caloric consumed by the Pouzin furnaces as follows:1. Caloric of reduction and of fusion of pig-iron = 2294 cals. Caloric in the slag, 1'198 x 500.. = 599 " Caloric absorbed by the limestone, of ore and flux, 0'991 x 373'5.... 355 " 2. Caloric absorbed for evaporation of water of ore, and coke, 0'144 x 606.. = 87 " Caloric taken for decomposition of moisture of air, 0'0062 x 4'5 x 3222... 90 " 3. Caloric carried off by gases, 6'442 x 150 x 0)237....... 229" 4. Caloric lost by radiation, etc. 300 " Total caloric consumed or necessary. 3954 cals. This figure must also represent the caloric received, which is made up of the caloric of combustion, and the caloric carried in by the blast. Now, admitting that the weight of blast is 41b *50, we have, as approximate value of the caloric carried in by blast (~ 16), 4'50 x 2900 x 0'239 = 312 calories. There remains, therefore, for the caloric of combustion, 364-calories, whilst the total calorific power of the carbon is 0'940 x 8080 = 7595 calories; so that we have, as final result, the caloric developed in the furnace 4 — 0'48 of 7595 the calorific power of the carbon burned. This is precisely the proportio`n fouid forfthe large blast furnace of Clarence Works (~ 17), which seems to prove already that the Pouzin STUDIES OF BLAST FURNACES. 125 furnace, notwithstanding its small capacity, was working under good conditions. But as we know the carbon burned and the caloric developed, it is easy to find, by the help of two equations, the value of my or C02 and y or CO. We have, on one hand, the equation (1.) of ~ 7: 3 3,,' 7 y+ 11my=p and, on the other hand, we know that the caloric of comlbustion is due to carbon burned to CO and C02. The formula (4.) of ~ 15 gives for this caloric 3 7 4 7 y x 2473 + ( y — y b 8080 _ 4642a formula which may be written thus:' 3 7 3 (4.) (-1 x 2473 -+ y m x 880 x b = Q. And from these two equations (1.) and (4.) we have 11(Q -2473. p Y= 7 8080.p Q) m 7 \8080p - Q -3 5607 11Q - 2473.p hence.ny -3- 5607 Let us now apply these expressions to the data of the furnace of Pouzin..... i::b is the carbon contained in the limestone^0M'951 = 0'600 + *351, therefore- b 0'12 x 0'951 = 0'114; K p is the carbons-eontumed plus the carbon supplied by the limestone; therefore p = 0940 + 0'114 = 1 054, ~ hence Q -36.4 + 8080 x 04114 = -4&G.6 calories, 11 /4s3- -206\ 11 -1957\ 21527 m =. — ~ _ =8516-)-..8 m 7 \8516 -A4 7 -3953] 27671 y -= 1b'645 and my- 1 lb'280. 126 STUDIES OF BLAST FURNACES. The gases therefore contain: / - t —1-64&-C0, containing O'b'-I5 carbon /37 7 1.280 C02 i; 0 —-349 " Total carbon 11b'054 = p. And from the values of m and of y we can deduce the quantities of oxygen and nitrogen which must be supplied by the blast, using the formulas of ~ 7. The formula (3.) determines the oxygen given up by the charge to the gases: 8 d — x 0114 + 0423-'Olb 727 and formula (2.) gives for total oxygen of blast x = Y (44 + 56 x m) —0'727 = 1lb'146 and hence for oxygen of dry air, z 0'97677 x.. - 1b'.119 For nitrogen, 3'33 z... =3'726 That is, for dry air = 4'845 Moisture of air, 0'0062 x 4'845.= 0'030 Weight of moist air = 4'875 And finally the gas will be composed of CO2..... 1'b 280 CO.1.645 N..... 3 726 Dry gases... 6 651 Water of charges.. 0 144 Moist gases... 6'795 We see now that the weight of air in blast, and of the escaping gases, are somewhat greater than the weights we STUDIES OF BLAST FURNACES. 127 assumed a priori. [But in reference to calorific effects, there is very nearly compensation; the excess of blast, 0'375, would take in 25 calories more into the furnace, whilst the excess of gases would carry off 14 to 15 calories above the numbers deduced by calculation. There would therefore be in reality an excess of caloric carried in of 10 to 11 calories, which should be compensated by a less caloric of combustion; that is, the caloric of combustion would be reduced from 3642 to 3632. If we would go very accurately to work, we must begin the calculation again with this last number in order to determine the values of m and y. The number Q, in the preceding formulas, would be reduced by 10 units. We should have 4553 calories, instead of 4563. But it is quite evident that this correction would be insignificant. It would give the value of CO 0'b'004 more (1649 instead of 1'645), and the ratio mn would scarcely be affected. In short, the figures above given represent sufficiently near, for practical purposes, the real state of things; and the result is, that the working of the Pouzin furnace is very satisfactory. The ratio m has almost attained the limit 0'80, at which the dissociation of CO does not take place. The gases are rich in C02 and yet cool. In these circumstances an increase of the height of the furnace could produce no sensible useful effect (~ 24). The consumption could not be reduced below 0'970 of pure carbon, unless the blast were superheated, as at Consett. This advantageous working of the Pouzin furnace must, in my opinion, be attributed, in great measure, to the high taering form of action. The gases are very uniformly distributed, and the reduction goes on very regularly. At one 128 STUDIES OF BLAST FURNACES. time, the director of the works tried to enlare the tunnelhead without modifying the system of charging. There resulted immediately a less regular working, and a greater consumption. Since that time the yield has been increased by forcing the weight of blast, but the consumption has not sunk below 0'970 of pure carbon. We now see, that indirectly, even without determining by C02 experimenting the value of m = C we can come at an approximate estimate of the manner in which the carbon is consumed in blast furnaces, and thus F aiteei the relative economy of their working. But this indirect determination of the value of CO2 depends on an estimate more or less hypothetic of the caloric consumed. It will always be preferable to determine the ratio by an analysis of the gases, which allows of our calculating with perfect exactness the caloric received. This is a system of controlling the working of blast furnaces easily realized. It may be confidently recommended to iron-masters. They can thus ascertain in what respect their apparatus is faulty, and remedy the fault with confidence. ~ 28. Another example of French blast furnaces.-I have now shown by the example of Pouzin, that it is not always necessary to have great height of blast furnace to get satisfactory results. I might multiply examples. I shall take the blast furnaces of Denain of 1865, in which, with a volume of 2750 cubic feet, and a height of 42 feet only, they have arrived at a yield of 30 tons per day of forge iron, consuming only 14150 to 1'200 tons of coke of 15 % ashes per ton of pig, STUDIES OF BLAST FURNACES. 129 and this with argillaceous ores yielding only 32 % to 35 %. These favorable results are realized chiefly by a more rational system of charging, and also, as at Pouzin, by their having a more contracted region of fusion than most of the English blast furnaces. Take now, as example, No. 1 furnace of Montlu9on, St. Jacques' Works, of which in 1867 the principal elements were, Capacity.... 4250 c. ft. Height.... 49 feet. Temperature of the blast. 315~ Temperature of escaping gases, 100~, arising from the hydrated state of the ores. Yield in twenty-four hours, 24 tons of gray forge iron. 10 Charges-hydrated ore in grains, with 1() slag from forge, contains about 40 % as a mean. Consumption per lb. of iron, k{cokei 1145 at17 % of ash and 3 of water, or 0'916 pure carbon. ores 2'547 flux 0'906 Slag produced.. 1470 This is again an example of economical working, and if we apply to this the methods of calculation above given in detail for Pouzin, we should again find a high value for the ratio C0'2 An increase in height would certainly not diminish the consumption, already very low. 9 130 STUDIES OF BLAST FURNACES. The only possible economy is that which would result from the use of higher temperature of blast. If now I am asked whence arises this great difference between the working of the French furnaces here named and those of the older types of Cleveland, I can only suggest the following reasons: — 1. The section of the French furnaces is generally more tapering than that of English furnaces. Hence there is a better distribution of the gases; the reduction goes on in the upper regions with a less combustion of solid carbon. It has been already remarked that it is to this difference in section,' in shape, that part of the economy of the furnace of Clarence 1866, compared to Ormesby 1867, and Clarence 1853, is to be attributed. 2. The manner tf charging is more studied in France. Its influence on the distribution of the blast is well known. It is seen that thus they approach most nearly to the ideal working, that is, to the reduction of the ores without burning solid carbon. 3. Lastly, the region of fusion near the twyres, the hearth, appears to me to be generally too wide in England. In the smallest furnaces of Cleveland the diameter of the hearth is never less than 6 feet, and in most of those of 10,000 cubic feet and 17,000 cubic capacity, it reaches 7 feet 3 inches to 8 feet 3 inches, and even 9 feet, and yet the height is often less than this diameter. But the capacity of the region of fusion has a direct influence on the consumption. For fusing a refractory ore, it is not necessary alone to have a certain amount of caloric, the caloric must be well distributed, so that the local temperature shall be intense, which cannot be realized save in a contracted space. STUDIES OF BLAST FURNACES. 131 We know by Tunner's experiments on the temperatures of the region of fusion, that near each twyre the zone of combustion is always very limited, and that if we desire to have a high mean temperature the zone of fusion must be contracted. Whatever be the dimensions of the body of a blast furnace this high temperature cannot be realized with a relatively low consumption, except by the use of narrow hearths high relatively to their diameter. This is a precaution too often neglected, not only in blast furnaces but also in lead and copper furnaces and in cupola furnaces. ADDITIONAL NOTE. During the impression of these pages, I have engaged in certain experiments on the caloric of the iron and slags running from the blast furnace. I shall publish these results soon. In the mean time I must say that the numbers adopted by Mr. Bell now appear to me somewhat high, and that in the estimates above given there may be some correction to make. All the general conclusions to which my study of the blast furnace has led me are in no way affected by this-only, the caloric carried off by radiation from the swalls of the furnace should be about 100 calories more than above given. APPENDIX. APPENDIX. NOTE I. p. 42. ON this subject Dr. Percy has the following observations: "In all the preceding experimental investigations concerning the composition of the gaseous currents of blast furnaces there is one source of error which should be particularly borne in mind. The gas from any given furnace was collected at successive intervals, and it is doubtful whether any method could have been adapted for collecting it simultaneously at different depths, except by the insertion of tubes through the sides of the furnace, which would have involved much additional expense, and which might not, after all, have yielded perfectly satisfactory results, as the gas from the centre, owing to variations in the velocity of the gaseous current in different parts of the same transverse sectional area, may not have the same composition as near the sides. Now, identity of conditions cannot be measured, even in the same furnace, for an hour, much less for a day; so that the gas collected at intervals, however short, from exactly the same part of the furnace, working with the same charge, may not have the same composition."* In Dr. Wedding's translation of Percy's work, the remark is intercalated: "The most accurate average composition of * Percy, vol. ii. p. 443. 136 APPENDIX. the gases will be got by analysis of the gases drawn from the main tube leading off the gases from the tunnel-head for further use. Here they are thoroughly mixed." NOTE II. pp. 50, 52. On the subject of refractory ores-" Minerais Refractaires" — " Strengfliissige Erze" as opposed to " Leichtfiiissige Erze"Mr. Lowthian Bell makes the following remark in section xliii. of his Chemical Phenomena of Iron Smelting: "In connection with the greater or less consumption of fuel, German writers on Iron-smelting make use of the terms' Strengfliissig' and' Leichtfiissig.' If these words have to be taken in their literal sense of comparative susceptibility to fusion, their use, in my opinion, may lead to error. There are, no doubt, some differences in the melting points of different kinds of iron and slag, but these, I apprehend, are trifling, and cannot account for the marked alterations just spoken of in the quantity of fuel required for mere liquefaction. The actual cause of the lesser quantity of consumption of fuel in small furnaces I have conceived and described as being due to difference in susceptibility of reduction, and not fusion. There is however a considerable difference in the temperature required for the complete formation of different slags. According to Plattner's experiments, although the temperature of fusion of the slag itself when formed varies much less for different proportions of acid and bases, forming singulosilicates, bisilicates, and trisilicates, the temperature at which slags are formed varies considerably. In general, singulosilicates require a higher temperature for formation-are APPENDIX. 137 "Strengfuiissiger" or " Strengschmelziger"-than bisilicates: and of singulo-silicates, that of Alumina takes for formation.. 2400~ C. Magnesia... 22000 to 2250~ " Barytes.... 2100~ to 22000 " Lime.... 2100~ to 2150~ " Iron and manganese. 1789~ to 1832~ " The silicates of oxides of manganese and iron (protoxide) differ very little from each other. The bi- and trisilicates of the different earths are formed at a lower temperature. Of the bisilicates those of barytes and lime form at 2100~ barytes and alumina 2050~ ~" " lime and magnesia 2000~ c" " r lime and alumina 1918~ to 1950~ The temperature required for the formation of compound silicate (for instance, CaO3 Si203 + A103 Si203, a frequently occuring slag) from the earths composing them, is very much higher than that at which slags which have been already fused can be melted. As the slags coming from smelting processes are seldom formed by fusing together these independent components, but more frequently from a mixture of silicates already formed —partly from the ores, etc., and generally of manifold combinations of the oxides of the earths-the temperature required for the formation of the new slag or compounded silicates will lie between their point of fusion and the temperature which would be necessary to form this new slag from the separate simple substances. Refractory slags-" strengfliissige"-which are always indications of faulty working of the furnace, arise either from 138 APPENDIX. insufficient temperature, or from injudicious combination of the charges, as when too much silica and too little of the bases, or the contrary, exists, or if among the bases there be an excess of alumina and magnesia. Such slags are recognized by their pasty nature, their earthy, half-fused appearance, and by the air-holes pervading them. On the other hand, the charge is a good combination when the slags flow out of a good consistency-as free from metal as possible-and when, for a given consumption of fuel, the maximum of ores can be used. Dr. Percy, while objecting to the principle of Plattner's method-because it assumes that alloys of gold, silver, and platina fuse at the mean temperature of the component parts -says we may accept his results as affording practical information of value. "The melting points of metals and their alloys are fixed and unvarying, except under extraordinary conditions of great pressure, and as they extend through a very wide range of temperature they may be conveniently employed in the determination and comparison of high temperature. " Plattner himself considered that he had only determined temperatures correctly proportioned to each other, and not absolute thermometric limits. This note is to explain what is meant by " Strengflissige Erzen" —" minerais refractaire" - as used by continental writers. NOTE III. p. 87. The beautiful inductive investigation of the large yield of pig-iron with small consumption of fuel in the Styrian and * Percy, op. cit. vol. i. p. 48. APPENDIX. 189 Carinthian furnaces, in section xliii. of Mr. Bell's work, is well worthy of study in reference to this conclusion of M. Ebelmen. Also Dr. Percy, vol. ii. p. 446, quotes Ebelmen in detail as follows: "If we compare two kinds of fuel, which act with different rapidity upon the air and carbonic acid, such as coke and charcoal, it is very plain that it will be necessary to increase the mass of the least'combustible of the two, relatively to that of the ore, in order that oxidation of the iron should not take place to a greater extent in one case than in another. Thus experience has proved that, on the average, twice as much coke (by weight) is required as charcoal to produce in the blast furnace pig-iron of the same amount and of the same quality. In the same manner may be explained the difference of consumption of the same furnace, working always with the same fuel, according as it is desired to produce different qualities of pig-iron. Thus, much more charcoal is consumed in order to obtain gray pigiron than white." Dr. Percy remarks-" There is no doubt about this fact, though there may be much as to Ebelmen's explanation of it." Dr. Percy's remark I do not agree with. The "fact" is open to the greatest doubt. NOTE IV. p. 87. The fact that charcoal decomposes C02 (burns under a current of C02 giving off CO) more rapidly than hard or soft coke, is proved incontestably by Mr. Bell's experiments, Nos. 818 and 819, p. 75, No. I. Part II. of Journal of Iron and Steel Institute. 140 APPENDIX. NOTE V. It is proposed in this Note to give a brief history of the "Theory of the Blast Furnace," with the view of showing how very recently correct notions on the subject were first published, even of the chemical phenomena involved; and that it is not more than ten years since any concentrated attention was given to investigate the physical phenomena, that is, the calorific phenomena accompanying the chemical phenomena, by a knowledge of which alone the natural limit to the economy of fuel can be determined. And further' it is proposed to examine whether any tenable objections have been made to Mr. Bell's theory of this subject, now reproduced and perhaps rendered even more precise by Mr. Gruner in the text, ~~ 4 and 5, where he defines what is, in respect of consumption of fuel, the ideally perfect working of a blast furnace. As to the theory of the blast furnace. In 1837-1838, Lampadius* taught his pupils that we may divide the blast furnace into four zones from above downwards, viz., into zones of calcination, reduction, smelting and collection of products, and that therefore the charges in moving downwards must undergo the following changes. In the zone of calcination, the gaseous substances are driven off; the water, and in some part the carbonic acid of the ores * Wilhelm August Lampadius, b. 1772, d. 1842, was chosen by the celebrated Werner, founder of the Royal School of Mines, to be Professor of Chemistry and Metallurgy at Freyberg. He introduced Lavoisier's Chemistry at Freyberg. He published his Handbuch der Allgemeinen Hiittenkunde in 1801-1810, 4 vols., and was all his life active in the publication of important works on metallurgy and chemistry. APPENDIX. 141 and fluxes. In the reducing zone, extending downwards nearly to the boshes, the desoxidation of the oxides of iron, by the carbonic oxide generated near the twyres, goes on, and the rest of the C02 is expelled. A small portion of carburetted hydrogen also comes into play, and there is also reduction by contact with incandescent solid carbon. Towards the end of reduction the reduced iron sinters together with the substances forming the slags. The other substances present in the charges, as manganese, phosphorus, sulphuric acid, titanic acid, and such like, are only very partially desoxidized in this zone. In the zone of smelting, extending down to a point in the hearth above the twyres, the reduction of the ore is completed, and also a part of the manganese, and the acids and earths desoxidized. There are therefore formed compounds of manganese, phosphorus, sulphur, silicium, aluminium with iron, and these mix or combine with the iron, which here also takes up a certain proportion of carbon, and thus Roh eisen, cast-iron, pig-iron, fonte, is produced, a substance more fusible than malleable iron. In February, 1839, Lampadius published this statement of his views in a small work, Die Neuere.Fortschritte im Gebiete der Gesammten Jiittenkunde, i. e. "Latest Progress in Metallurgical Science and Practice." That this was not the generally received theory of the process going on in the blast furnace is shown by the following abstract of a paper "On the Reduction of Iron Ores in the Blast Furnace by Hot and Cold Blast, and with Raw and Coked Fuel," published by IKarsten in 1839.* It has been asserted, says Karsten, that in cases where not * Archiv fib Miineralogie, etc., vol. xii. p. 528. 142 APPENDIX. only fusion has to be effected, but reduction of oxides must take place, this reduction is hastened by complete contact of the fuel with the ores; and hence it has been recommended that the fuel and ore should be mixed before being charged into the furnace. But it is well known, that it is only necessary to begin reduction on the surface of a body, and that the process penetrates to the interior without any immediate contact with the reducing agent being necessary. M. Le Play has, it is true, recently and repeatedly called attention to the reducing power of carbonic oxide. He has shown that oxides of iron, in circumstances where they could not come in contact with solid carbon, were reduced at a certain temperature by carbonic oxide made in a tube in which carbon was at one end, oxide of iron at the other, and the air was sealed up with the two-that the carbonic oxide first formed was transformed to carbonic acid by the oxygen of the ore, and reconverted to carbonic oxide by the carbon, and so on in succession, till either the carbon was burned or the ore was completely reduced. "But," says Karsten, "the oxides of iron are unquestionably not reduced in this way in the blast furnace, because the CO formed by the incandescent carbon in contact with CO2 rushes too rapidly past to the top of the furnace, and because the oxides of iron are everywhere in contact with incandescent carbon, by which the reduction can be begun without its being necessary to decompose a gas, which would, besides, have to take place under circumstances which would rather favor the generation than the decomposition of the gas (C02)." Assuming that the process of reduction above described was correctly conceived, IKarsten proceeds to take into consideration the products of combustion, and concludes, "that APPENDIX. 143 the formation of carbonic oxide takes place in the upper part of the furnace by the reduction of the ores by solid carbon." "But," says he, "the reduction when only CO is formed takes twice as much fuel as when CO2 is formed; and if there were any means of preventing the formation of CO here, this would be at the same time the means of reducing the ores with the least expenditure of fuel." We now know that the air blown into the furnace at the twyres is almost instantaneously transformed into carbonic oxide, and this gas, in its passage up the body of the furnace, acts more or less directly in reducing ores; that is, with or without the aid of the solid carbon (see ante, p. 25). We also know that, in the presence of CO2, iron is practically reoxidized, and that in the presence of equal volumes of CO and CO2, peroxide and metallic iron are both brought to the state of oxide. The doctrine of Lampadius was much nearer the truth than that of Karsten, and is, in fact, the explanation still given of what goes on in the blast furnace (see Percy, vol. ii. p. 444), but great strides had yet to be made, and that very year, 1839, before the printing of the number of Karsten's Archiv in which his notions above given was finished, Bunsen's first experiments on the composition of the gases at different depths of the blast furnace, at Veckerhagen, were published as an Appendix to Karsten's paper. In his report of the experiments Bunsen writes: "They prove that too much weight has hitherto been laid on the desoxidation of CO2 to CO at the cost of incandescent carbon. Some of my experiments demonstrate that, in the combustion of charcoal, the first immediate product is CO, provided there be no 144 APPENDIX. surplus supply of oxygen to burn the CO to C02, and thus one-half the calorific effect of the fuel is lost." Thus began to be formed a theory of the blast furnace. But such as it was, the theory was still only a qualitative analysis, so to speak. Bunsen first began the quantitative analysis, and first gave a calculation of the quantity of caloric used in thefurnace, and of the quantity carried off in the gases, and pointed out for what purposes this lost heat might be made available. For a particular case of analysis of the gases collected 5 feet under the tunnel-head, 49'55 per cent., or onehalf of thefuel was proved to go off as CO, and was lost, and that besides the sensible heat of the gases themselves being 9930 C., 25 % more of the fuel was lost in this way; so that 75 %o altogether was lost.* The researches of Ebelmen on the composition of the blast furnace gases were begun at the same time as Bunsen's researches, but were published a year or two later.t Ebelmen made his calculations of the quantities of caloric used, and of the temperature in the furnace, by adopting Dulong's calorimetric results, given in the Comptes Rendus, 1838, p. 874,: and arrived at the conclusion that 64'8 % of the fuel went off in the gases and was lost. Ebelmen pointed out that the gases escaping would suffice for heating the blast, supplying the steam for blast engine, and for the desiccation of the wood used in the furnace itself. * Karsten's Archiv, vol. xii. p. 547; 1839. f Annales des Mines, 1841-43, and collected Memoirs, published in Paris, 1861. f For the combustion of C to C02 Dulong found 7167 cals., but it is 8080 CO to CO2 " 4" 2634 cals.,'" " 2473. APPENDIX. 145 Such was the progress made towards a rational theory of the blast furnace-chemical and physical-and of its application to determining the calorific efficiency of the fuel consumed, in 1842; and very little progress was made for several years afterwards either in diffusing or extending the notions then attained to. And now it is interesting to show how, in this department as in many others, art is the mother of science. Long before an analysis of the gases of blast furnaces was made, or could have been made, practical men perceived the uses to which the gases could be turned. For this object a quotation from Dr. Percy's great work, vol. ii. p. 663, will suffice: "In June, 1814, Berthier published an interesting and important paper* on the successful application, in France, of the waste gas to various purposes, such as the conversion of iron into steel by cementation, and the burning of lime and bricks. The credit of this application is due to M. Aubertot, who was a proprietor of ironworks in the department of Cher. He obtained a patent for it in France in 1811. Berthier visited four works, either belonging to, or managed by, M. Aubertot, so that his description was founded on personal observation; and it is very just to his memory to state, that he seems clearly to have foreseen the value of the application in question. The calorific effect of the waste gases was rightly attributed by Berthier, partly to the sensible heat, and partly to the heat developed by combustion in contact with atmospheric air." Mr. Moses Teague took a patent on this matter in 1832. Mr. James Palmer Budd obtained a patent for the applica* Journal des Mines, 35, p. 375; June, 1814. 10 146 APPENDIX. tion of the " heat, flames, and gases of the blast furnace to the heating of hot-blast stoves" in 1840. This application was carried into practice at Ystelyfera, and so satisfied was Mr. Budd with the success that he even ventured to draw the following conclusion: "It would appear to be more profitable to employ a blast furnace, if as a gas generator only, even if you smelted nothing in it, and carried off its heated vapors (sic) by flues to your boilers and stoves, than to employ a separate fire to each boiler and each stove. These considerations irresistibly suggest to me a great revolution ill metallurgical practice, a new arrangement, in fact, of furnaces and works by which considerably above ~1,000,000 a year might be saved in the iron trade alone (1848)." This was excusable in the first enthusiasm, but it is well known that it is only when a low class of coal has to be used that generator or "producer" gases are not wasteful, except where intensity of heat is required. Let us revert now to the progress made since 1842 in the chemical and physical theory of the blast furnace. Bunsen's calculations were founded on the truth of " Welter's law," by which the caloric evolved in the furnace would be to the potential caloric of the gases escaping as the weight of the oxygen burned in the furnace is to that of the oxygen required for complete combustion of the gases escaping. Welter's law is not universally true, and it is certainly not true for this application. Ebelmen could only refer to the calorimetric determinations of Dulong for his calculation of the development of caloric in the combustion of carbon and carbonic oxide.* Since then * It is interesting to mention here that in the fandbuch der Chemie of L. Gmelin, published in 1843, he remarks-" Dulong's determination of the APPENDIX. 147 we have the more accurate determinations of MM. Favre and Silbermann, and of Professor Andrews, of this and other essential elements of the calculations in question, and besides these, more accurate knowledge of specific heats of all substances, as may be gathered from the study of modern works on chemistry and physics; or, for the present special question, in the works of Dr. Percy, Mr. Bell, M. Gruner, and Mr. Schinz. In 1863-64 the "Metallurgy of Iron and Steel" was published by Dr. Percy, and this was certainly an epoch in the literature of this important subject, not only in England, where it was the first work on metallurgy of any scientific value ever published, but in Germany and in France, where the work was immediately translated by eminently qualified metallurgists. The German translation by Dr. Wedding is still in progress. Dr. Percy says, p. 444, vol. ii. —" As far as I am able to judge, the importance, whether in a scientific or practical point of view, of the results of the analysis of the blast furnace gases has been somewhat over-estimated. Temperature, carbonic oxide, and incandescent carbon, explain all the phenomena of the blast furnace," and Dr. Percy does perfectly explain them in the next subsequent pages of his book, with just a little more preciseness than Lampadius did in 1838. quantity of caloric from the combustion of carbonic oxide is, woithout doubt, much too high. If it were correct, then carbon in combining with the first atom of oxygen must develop much less caloric than with the second, which is extremely improbable." But we know now that this is exactly what occurs-so the exact science of to-day was a stumbling-block to the ablest men of science only twenty years ago. Let us learn to be cautious in accepting even scientific authority as final, and very humble in the assertion of scientific opinions. 148 APPENDIX. The physical phenomena-the calorific phenomena of the blast furnace were not, as far as my knowledge of the subject goes, taken into serious consideration till Mr. Schinz, of Strasburg, began his investigations about 1864. In 1868 the Dokumente betreffend den Hohofen zur.Darstellung von Roheisen was published,* and in this, for the first time, the advancement in calorimetric determinations of the heat absorbed or evolved in chemical combinations, which science had gained since the early experiments of Dulong, Despretz, and others, were applied to determine the principles on which the economy of the blast furnace depends. Schinz's work contains much useful information. Laborious calculations are unfortunately expended on questions of no practical interest, and some fundamental mistakes were made in this first attempt to construct a balance-sheet between caloric received and caloric expended altogether vitiating the results. The original, or, better, the translation, should nevertheless be in the hands of every student of the phenomena of the blast furnace, if only to show the difficulties and complications of the question, and how even men of unquestionable scientific attainment may be misled by one false step in their reasoning into a maze of calculations based often on guess-work and having no practical use. Schinz undertook a series of experiments on the conditions under which ores are reduced, and the laws upon which this reduction is based, upon which he "spent years of labor in * A good translation of this work by W. H. Maw and M. Miiller, under the title Researches on the Action of the Blast Furnace, was published in 1870. APPENDIX. 149 order to acquire this knowledge as exactly as possible."* These investigations aspired to determine for the process of reduction, a. The influence of temperature. b. The influence of the quantity of gas passing in unit of time. c. The influence of the proportion of CO in the gases. d. The influence of time of exposure to gases. e. The influence of the nature of the ores; and f. The conditions of carburation of the iron. Schinz after a time convinced himself that correct and useful results could only be attained if such gases were experimented with as are really to be found in the blast furnace. These gases he prepared artificially, so far as the proportion of CO to nitrogen is concerned. The pyrometer used was a thermo-electric element, very specially arranged, and for which Schinz calculated tables of correction, but the relative thermometric determinations he considered as generally too high. Ten different qualities of ores were experimented upon: Red iRaematite-brown ores from Hayange-from Nassau — Spathic ores from Siegen-Oolithic ores from Namur- artificial ores-viz., 100 oxide of iron, 100 carbonate of lime, 25 carbon, and others as bases of pure oxide of iron. The experiments made with the " Reductometer" impressed him with the opinion that there is no justification for a distinction between the zone of fusion and that of carburation; * Dokumente, p. 57; translation, p. 88. Op. cit. p. 1; translation, p. 6 et 8eq. 150 APPENDIX. for the carburation begins at a low temperature with the appearance of the first molecules of metallic iron. This temperature he found by his pyrometer to be between 780~ and 7860 C. And further on in. his reasearches Schinz writes-" It is therefore almost impossible that the iron can receive carbon from any other source than the carbonic oxide, or at other place than in the zone of reduction." The experiments showed that at 400~ of the thermo-electric pyrometer no reduction takes place. Measured otherwise, Mr. L. Bell found that reduction is complete under this temperature (see postea, p. 152). a. We must cite an example of the influence of temperature* on the rate of reduction of red iron ore from Dillenburg, sp. gr. 5'4-30 % of oxygen combined. No. of Experiment. Hourly absorption of O. Temperatures (by pyrom.) 21.. 1-60.. 421~ 22.. 2'55.. 546~ to 621~ 23.. 2'70.. 823~ to 861~ 24.. 4.45.. 884~ b. The influence of quantity of gases passing in unit of time was proved to be such that, for instance, with a double flow of gas, the reduction was as 5-62 % to 4'75 % of the total oxygen absorbed per hour, for temperatures varying from 4990 upwards in the one case to 720~ upwards in the case of the less supply of gas.t c. The influence of the quantity of CO in the gases was found to be such that when 49'32 % CO was present, the reduction per hour was just twice as much as when the * Op. cit. p. 77; trans. 112. t Consult Bell's work, section iv. and section xi. APPENDIX. 151 contents were only 34'65 per cent. for the sanle temperature and same absolute quantity of gas. d. The influence of time was, as might be expected, quite evident through all the experiments. e. The quality of the ore. The result of these experiments was that " the richest and most compact ores gave under all circumstances the most favorable coefficient of reduction, but neither the specific gravity nor the contents of iron in the ores have any recognized proportion to the reduction, so that experiments for each ore would have to be made. f. The carburation of the iron. The experiments prove that carburation of the iron begins' with its reduction, that is, as soon as metallic iron appears. The observation that the carbon of the CO combines with the iron instead of reducing it is proved by experiment 50; for instance, where an abundant carburation took place at 780~ (by pyrometer), although not one-half of the iron was reduced from the peroxide. The greater the percentage of carbonic oxide in the gases the greater is the transfer of carbon to the iron when reduction of the iron is complete. Exp. 68, p. 77; trans. p. 111. Further, Schinz, after examining critically the analyses of the gases of the blast furnace which were made by Bunsen and Ebelmen in 1839-40, and pointing out their insufficient accuracy, put the question, What is the practical application of such analyses? The answer given is almost the answer we give now, viz., that when we have an exact knowledge of the composition of the charges, it is possible to calculate from the analysis of the waste gases the amount of carbon which passes by direct reduction-reduction by solid carbon-into 152 APPENDIX. the gases, and which was therefore not burned at the twyres by the air of the blast. This chapter is worthy of attentive study. Schinz concludes that the analysis of the waste gases is, even to the practical metallurgist, a valuable means of ascertaining what takes place inside his furnace in reference to the consumption of fuel. The services of Schinz in enlarging and rectifying our notions of this important element of the theory of the blast furnace are not sufficiently recognized. In the calculation of the calorific effects produced in the blast furnace, M. Schinz started with a fundamental error in the calculation of the production of heat by combustion of carbon to C02 and the reduction of CO2 to CO. This error having been pointed out to him by M. Luhrmann of Osnabriick, it was corrected in 1871, in Douglers' Journal, vol. 201, p. 231; but even there the correction is not perfectly satisfactory, as it imports into the subject the latent heat of gasification of carbon, about which nothing positive is known. No injustice is therefore done in not entering on Schinz's results of calculation, which are further rendered useless by erroneous notions of the loss of caloric by radiation, etc., from the walls of the furnace. And now we come to the present state of the theory of the blast furnace-that which gave rise to Mr. Gruner's Studies, and the foregoing translation. Mr. Lowthian Bell, a hereditary iron-master, brought up from his youth in the midst of blast furnaces and great chemical works on the Tyne, and besides, having a thorough scientific education and a genial disposition to give freely all information he possessed, and to take kindly all given him APPENDIX. 153 by his neighbors and compeers in the trade, began in June, 1869, to contribute a series of papers to various Societies on the Chemical and Physical Phenomena of the Blast Furnace, which may be truly said to bring the theory in every respect to the actual level of the sciences of chemistry and physics, and to point the way to practical improvements, or at all events to put a scientific test of their working in the hands of furnace managers.* Mr. Bell first examined the notion of "zones" of reaction in the furnace as used by Lampadius in his explanations of blast-furnace theory in 1838, afterwards adapted by Scheerer in 1853, and by Tunner later. He has constructed diagrams to scale of the results reported by these experimenters, as well as those obtained by Ebelmen in 1844 at Clerval with regard to reduction of the ores and the commencement of carburation. Practical men could thus for the first time see what the experiments had really ascertained, and that the lines of demarcation between the different " zones" were not meant as having any horizontal divisions or other very precise form. What Lampadius taught on this subject was that four or five changes took place-pedetentim et graduatimin the descent of the charges against the ascent of the counter current of gases, and that there were zones in which these changes began and ended. Mr. Bell points out, that, as in practice a uniform descent of the materials in a furnace is interfered with by the difference in size and specific gravity of the ironstone, lime, and coke-by the friction of the sides of the furnace, more especially on the boshes, and by the mode * Journal of the Chemical Society, June, 1869; Report of the British Association, etc., Exeter meeting, 1869; Transactions of the Iron and Steel Institute, 1869; Journal of the Iron and Steel Institute, 1870 to 1871. 154 APPENDIX. of charging, whether central by a narrow tunnel-head, or all round as by a wide mouth-therefore the zones could not possibly have any shape such as given in Scheerer's work, and since repeated in books by several continental scientific metallurgists.* But it is also pretty certain that zone is a figurative expression for a region of change of temperature, change of reaction, etc. However this may be, the examination of the notion of zones led Mr. Bell to make a series of direct experiments on reduction of ores by the gases escaping from the blast furnaces, and the true deduction from these experiments is that the reduction of calcined Cleveland and other ores, Fe203, is begun and ended by these gases at a much lower temperature than had been supposed proved by the experiments of Scheerer, Tunner, and Ebelmen, of those found by Schinz; for the temperature of the furnace gases, from Cleveland furnaces, of capacity varying from 6000 cubic feet to 26,000 cubic feet capacity, was seldom above 336~ C., melting point of lead, and never above 450~ C., the melting point of zinc..A certain size of the pieces of ore retards reduction, and even delays its commencement until sufficient heat is imparted, but the temperatures above given are, with time, sufficient to completely deoxidize ores of iron.t Of all the substances found in "pig-iron"-and Fresenius * Jfetallurgie, 1848 to 1853. t The beginning and ending of the process of reduction was as follows:Began. Ended. By Scheerer 4000 C. 1000o to 12000 Tunner 6800 14000 Ebelmen. Below red heat. Incipient fusion of ore. See also, page 148, the experiments of Schinz. APPENDIX. 155 made an analysis of a "Spiegel" iron of St. Louis near Marseilles, in which he found some twenty substances besides iron-and although no case occurs in which some two or three impurities do not occur, no substance is really essential to its constitution except carbon. The circumstances which determine the union of this indispensable element with the metal are of high interest to the smelter, because upon the quantity and condition in which the carbon is associated with the iron depends, it is considered, the different qualities of the article he is manufacturing. The portion of the furnace in which the combustion takes place, the temperature necessary for effecting it, andl the exact source of immediate supply, have engaged the attention of all metallurgists who have studied the subject. Scheerer says that carburation takes place only after all traces of unreduced oxide have disappeared, and where the temperature ranges from 10000 to 1600~ Centigrade. Tunner considered that his experiments proved that this combination takes place when the furnace has the temperature at which cementation takes place in steel furnaces, taken at 1150~ Centigrade. Mr. Bell, on the other hand, found that "an exposure of three hours to a temperature a little above the melting point of lead, and below that of zinc, sufficed to give a black deposit of carbon in a minute state of subdivision, so that he really believes it to be combined with the iron, or deposited by chemical action in such a form as to present great facilities for subsequent combination. It therefore seems probable that instead of the lowest and hottest portion of the furnace being the zone of carburation, this change occurs high up, 156 APPENDIX. where the temperature is comparatively low."* Foreign ores treated exactly as were the Cleveland ores in the gases of the furnaces, showed unmistakable signs of this carbon impregnation. And moreover, the raw iron-stone gave rise to a blacker and larger deposit than the calcined. The deposit was 1'68 per cent. of the iron in the ore in the calcined, and 4'63 per cent. on the raw ore, after each had been exposed twenty-four hours in the escaping gases. In September and October, 1869, Mr. Bell read papers "On the Development and Appropriation of Hteat in Iron Blast Furnaces of different Dimensions," before the members of the Iron and Steel Institute. In this paper there are explained all the principal elements of the Calorific Phenomena of the blast furnace; and many of the remarkable results worked out during succeeding years are given in a preliminary shape, sufficiently accurate to warrant the conclusion stated then, that a capacity of 11,000 to 12,000 cubic feet, and a height of 70 to 80 feet, is sufficient to realize all the economy it is possible to derive from this element of blast furnace engineering in Cleveland circumstances. This paper was an appropriate introduction to the remarkable series of investigations presented to the Iron and Steel Institute at short intervals from 1870 to 1872, forming "an experimental and practical examination of the circumstances which determine the capacity of the blast furnace, the temperature of the blast, and the proper condition of the material to be operated upon." * -Mr. Bell found charcoal just as suitable for carburizing iron as precipitated carbon, but considers the latter the mo8t probable source of the carbon of combination with the iron on account of the intimate mechanical mixture with the iron for its precipitation. APPENDIX. 157 In the course of these researches, Mr. Bell completely filled up the details of what he had sketched out in reference to the chemical and physical theory of the blast furnace in 1869. If he has not exhausted the subject, he has at least left no point of the theory unexamined by all the light and methods of investigation of modern chemistry and physics. It only requires an examination of the headings of the forty-five sections of Mr. Bell's work to perceive how the minutest point has a section dedicated to it as conscientiously as is done for the most essential. But the investigations which were made on the presence of alkaline cyanides in the blast furnace, in section xxvi., and on the part they play in the processes going on in the furnace, are so very important and interesting that I must attempt to give a summary of them. Messrs. Bunsen and Playfair, in their " Report on the Gases evolved from Iron Furnaces, with reference to the theory of the Smelting of Iron"-made to the British Association at Cambridge in 1845-called attention to the fact that the gases from the lower part of the furnace, immediately over the point of entrance of the blast, contain cyanogen, which again disappears a short way above that point-so that at the top of the boshes* only traces of it are observed. And they remark, "The compound of this substance with potassium appears to play a most important part in the furnace, although its functions have apparently been altogether overlooked." Their detailed experiments led them to the conclusion that this cyanide of potassium owes its forma* The Alfreton furnace was 40'5 feet high, and 11 feet diameter at the widest. 158 APPENDIX. tion to a direct union of carbon with potassium and nitrogen of the air. Messrs. Bunsen and Playfair estimated-all corrections made —that in every cubic metre of gas at 2'75 feet above the twyres there was to be found 8 to 10 grammes of cyanide of potassium. Their experiments further showed that the cyanide of potassium is volatile at high temperatures. Thus, carried up by the ascending currents, it exerts its well-known reducing power —is thus decomposed into nitrogen, carbonic acid, and carbonate of potash —the gases passing off by the top, the potash falling back to the region where it is again converted into cyanide of potassium, under the influence of the carbon and nitrogen. "hence a large quantity of ore may in this way be reduced in the lower part of the furnace by a comparatively small quantity of regenerated cyanide of potassium." Dr. Percy,* in examining the figures given by Bunsen and Playfair, concludes, "that, unless the oxidation and regeneration of the cyanide of potassium takes place with a degree of rapidity hardly admissible, its service as a reducing agent must be so inappreciable that it may well have been'previously entirely neglected.' "t The phenomenon of a decrease of oxygen, as the gases leave the twyres, when compared with the atmospheric nitrogen, had been observed and an explanation proposed by Ebelmen. Dr. Percy: says, " such a decrease implies an abstraction of oxygen from the gaseous current, and its fixation in a solid state of combination, or an evolution of nitrogen in sensible Op. cit., vol. ii. p. 451. t Rep. B. A. 184,5, p. 186.: Vol. ii. pp. 444, 445. APPENDIX. 159 quantity from the solid contents of the furnace; but I cannot understand how either of these results should occur:" and further on he writes, "I have failed to elicit from these analyses of gases any satisfactory general expressions such as might reasonably have been expected. I must, therefore, leave the reader to examine each'table' for himself, and draw his own inferences therefrom." But, as Mr. Bell observes, Dr. Percy makes no allusion to the alteration in the quantity of carbon, gauged by the same standard. Mr. Bell therefore selected four of the examples in the "tables," and these show incontestably that as a certain volume of gas ascends, it loses oxygen, but in addition to this, they prove that there is a simultaneous disappearance of carbon. Mr. Bell gives the following statement of the loss of oxygen and carbon in the gases at 111 feet above the twyres of an 80-feet Wear furnace:Oxygen. Carbon. Example 1.. 2'83 cwts. 1'37 cwt. "4 2.. 319 " 180 4 3.. 243 1" 1P65 3" *' 4.. 251 " 1"91 Average 2-74 cwts. 1'62 cwt. The undoubted disappearance of carbon from the gases of the furnace as, they leave the hearth leads necessarily to inquire whether it may not throw some light on the simultaneous diminution in the quantity of oxygen. "The form of combination into which the missing carbon has entered, I venture to suggest, is chiefly cyanogen, and possibly to some extent carbonic acid, both united with the 160 APPENDIX. alkaline metals, which I have shown abound in the lower region of the blast furnace." Mr. Bell then shows that there is much probability that the 1'62 cwt. of carbon, above ascertained as an average, assumes the form of 3'51 cwts. of cyanogen per ton of iron yielded. This assumes that about 40 grammes of cyanogen are present in the cubic metre of gases. (Dr. Percy's calculations were founded upon an analysis of Bunsen and Playfair giving only 4 grammes.) Admitting the probability that the carbon has assumed the form of cyanogen, it remains to consider in what way this action has led to a still more marked change in the quantity of oxygen, viz., 2'74 cwts. But even Mr. Bell fails to draw up any general theory which will fit every change which makes itself apparent in a blast furnace. These changes are well known to every intelligent manager to be numerous and sudden, and frequently take place without any apparent cause. The sum of all the evidence goes to show, that the quantity of cyanogen would account for the largest weight of carbon in excess which appeared at the twyres; and the presence of so large a quantity of cyanogen and alkaline gases appears to justify Mr. Bell's conclusion, "that it is to these substances that the apparent excess of carbon and oxygen in the lower region of the furnace has to be attributed." Many other modes of reaction besides the direct union of C and N, in the presence of K and N, might be suggested as accounting for the disappearance of C and O from the gases, and Mr. Bell has illustrated this, p. 254 to 256, and we shall not enter upon the subject. It is of great interest to record here Mr. Bell's own summary of what he "conceives to be the action proper of the blast furnace, i. e., supposing no alkaline substance to be present. APPENDIX. 161 This, no doubt, is a condition of things not to be found in practice, but experiment would indicate (vide section xxvi.) that the alkalies, along with their associated cyanogen, are not indispensable for the reduction and carburization of iron. This imaginary process would consist in the volatile constituents of the roasted ore, viz., its oxygen, being expelled probably before it has passed the first 10 or 12 feet of the furnace. This is inferred because already, at a depth of 16J feet, there are only 2'06 cwts. of oxygen due to the minerals present in the gases, and of this 1'03, or something like it, has been contributed, not by Fe203, but by P205, SO3, Si02 and CaO. The remainder, 1'03 cwts.,along with a certain quantity of carbon, 0'34 cwt., is probably due to the carbonic acid of the flux, seeing that it requires a higher temperature to split up CaC03 than to reduce an oxide of iron. From the point B in the furnace (vide diagram, example of original 1) the oxygen in the gases remains almost stationary until we approach the twyres, where the small quantity of 0 absorbed by the iron in the dissociation of CO, and that combined with the P, S, Si, and Ca, found in the iron and slag, alone ought to appear. Here also the quantity of carbon in the gases ought to be that furnished by the coke, less the portion which may have been carried off by the reduction of CO2 to CO in the manner already described." "Simultaneously with the process of reduction is the deposition of carbon by the splitting up of CO into C and C02, and that this takes place very soon after the immersion of the ironstone among the gases, seems to admit of no doubt. This operation of carbon-impregnation will continue until the iron or its lower oxide is sufficiently heated to suspend 11 162 APPENDIX. further action, in the manner already fully explained in the sections upon the dissociation of CO." "No doubt, even in this supposititious case of the absence of the alkalies K120 and Na20, there would ensue irregularities in the composition of the gases at the same position in the furnace, which might result from a retarded or accelerated rate of reduction, from the nature of the ore itself, or from some of those mechanical causes which have been spoken of. Substantially, however, I apprehend there would not be found any of those discrepancies, to explain which I have bestowed some pains, and which, in my judgment, are to be entirely attributed to the presence of the alkalies, potash and soda, and the consequent generation of cyanogen." "If I am correct in this supposition, and if the experimental proof of the great fluctuations in the quantities of these substances is to be relied upon, it is not difficult to comprehend that there must necessarily be corresponding irregularities in the character of the products in different parts of the furnace." Such is the explanation of the action proper of the blast furnace in 1873. The generation that has lived since Lampadius taught has seen such precision given to the expression of the chemical phenomena going on in this vast apparatus as takes it out of the domain of empiricism, and puts it into that of exact science. But it was not till 1870 that the phenomenon of dissociation of carbonic oxide-the splitting up of CO, so that 2 CO is transformed into CO2 + C —was discovered, and that all the conditions of this phenomenon were examined experimentally and described. Though Mr. Schinz had observed the deposit APPENDIX. 163 of carbon, and had applied the facts to explain carburation, he gave no explanation of its origin. From Mr. Bell's experiments it seems highly probable that carbon impregnation, as he terms the action, by the splitting up or dissociation of CO, takes place at nearly as low a temperature as desoxidation, which, in the case of Cleveland calcined ore is begun at 200~ to 210~ C. (section xi. p. 46). And as the extent of reduction in different ores is affected apparently by their molecular condition (section iv. pp. 17-19), when submitted under perfectly similar circumstances to the action of CO; so the same irregularity in the extent to which carbon impregnation takes place has been observed for different ores. Generally speaking, the more readily an ore or oxide of iron loses its oxygen, the more capable it is of dissociating carbon from CO. Very small differences of temperature greatly affect the quantity of carbon yielded by the CO. In experiment 211 (p. 48), 100 Fe in calcined Cleveland ore, at a temperature not visibly red, the carbon deposited in 41 hours was 64'0 C. Using the same ore the following figures were obtained: — Carbon deposited. Exp. 228. Temperature for 11 hours red and 10 hours bright red-in all 21 hours. 2'3 % of Fe. " 229. Temperature very bright red for 6~ hours...... 03 " Practically it may be assumed that the phenomenon of carbon impregnation diminishes very rapidly as soon as a red heat is reached. The temperature most favorable for its production is between 4000 C. and 4500 C. But if the ores with carbon deposited at this temperature be only partially reduced, 164 APPENDIX. and exposed to a bright red heat, the carbon will be consumed to the extent at least of the supply of oxygen in the unreduced portion of the ore. It remains therefore a question whether all the carbon necessary to constitute the various qualities of pig-iron is the result of carbon impregnation accompanying the process of reduction in the upper portion of the furnace, or whether a portion is derived from the incandescent carbon of the hearth. The only other point on which it seems useful for me here to attempt to give the results of Mr. Bell's investigations, is that of the behavior of limestone in the blast furnace-its use as a flux, and its use for removing sulphur in Cleveland ores. On this latter point it has been proved that these ores may be used without lime, but then the "pig" contained much more sulphur than when lime was used, viz., 0'33 %, and the quality in point of strength suffered considerable deterioration. But the most interesting question in reference to the limestone is, What becomes of the carbonic acid united to the lime? The use of CaO C02, as a flux, is the usual means by which CO2 finds its way illto the blast furnace. The C02 which we find in the gases owes its origin, be it repeated, to the expulsion of that contained in the limestone, to the desoxidation of the ore, and to carbon deposition by the reaction so fully described. Mr. Bell concludes, from experiments directed to this point in section xxi., that as carbonic acid in an atmosphere of CO2 is only sparingly given off at a full red heat, and CO2 commences to undergo decomposition at 4000 to 500~ C., all the CO2 entering the furnace combined with CaO, leaves it as CO, and adds, "this view of what really takes place in the furnaces in the Cleveland district is further confirmed by the fact that the CO2 in the gases never APPENDIX. 165 exceeds that due to reduction of Fe203, and to the dissociation of that portion of CO which furnishes the carbon found in the pig-iron." In opposition to this conclusion the note at foot of p. 65 of M. Gruner's "Studies" must be referred to, where it is proved that in the special example of a Clarence furnace the 01b'058 of carbon absorbed to transform C02 into CO is less than the 01b'082 of carbon in the limestone. The experiments are very difficult to make with such precision that well-defined conclusions can be drawon (see Bell, section xxi. p. 110, note). The application of the phenomenon of dissociation and of the decomposition of the CO2 in the limestone takes place in estimating the quantity of caloric required in the process of ironsmelting. Mr. Bell's services in this part of the theory of the blast furnace are unique. His papers on the subject have been translated into German by P. Tunner, into Swedish by Rinman, and the work of M. Gruner testifies to the interest it has excited in France. Bell's experiments, showing the reactions that take place between the oxides of iron and iron itself, and the CO and CO2 of the gases of the furnace, demonstrate the fallacy of calculating the calorific efficiency of the fuel in a blast furnace upon the supposition that it can all be resolved into C02, as was done before the Institution of Mechanical Engineers in November, 1868, and afterwards in January, 1869. They prove that we must content ourselves with ascertaining to what extent the carbon applied in a furnace can be made to assume its highest state of oxidation, for which it produces 3'28 times as much caloric as when it takes only the lower state-that is, Mr. Bell first proved that the proportion of C02 in the blast furnace gases 060 166 APPENDIX. is the index of the calorific efficiency of the furnace. After the complete manner in which this proposition has been demonstrated in M. Gruner's text, it is quite unnecessary to refer to it further. This point is no longer questioned, although it is often overlooked by persons taking part in " discussions" of papers on the limit of the economy of fuel in blast furnaces. There is in fact only one rational way of estimating the quantity of heat required in the process of iron-smelting. There are questions open as to the values to be given to certain factors, to certain experimental data, but there should be no question as to the principle of calculation which is alone available. There should be no question now as to the principle of calculation of the heat received and developed in a furnace, nor of the heat absorbed in the chemical action and in fusion, and carried off by radiation and reaction from the walls and foundations of the furnace, in the twyre water, and in the sensible heat of the escaping gases. Some years ago calculations were put forward for determining the consumption of fuel by another method. Various assumptions were made, for instance that it is impossible to have a greater proportion of C02 to CO in the gases of a blast furnace than I C02 to 4 CO, when the CO02 of the limestone is eliminated-i. e. an assumption at variance with almost all experience of furnaces of fair proportions and in good working order-as, for example, the six furnaces examined in this book, in which the proportions (after elimination of CO2 of limestone) are 1 1 1 1 1 1 and 4 2'73 3'55 3'4 2'19 2'9 respectively. The proportions of limestone (carbonate of lime) for these examples being in cwts. to the ton of iron, 16 13'5 12'5 8 8 18 APPENDIX. 167 whilst the proportions in the calculations in question were taken at 8 to 10 cwts. But the assumption that the CO2 of the limestone passes off entirely as such in the gases is gratuitous. It is still an open question. It is assumed further, that it is by the caloric due to this composition of the gases C02 I (calculated at 6000~ Fahrenheit units), that all the calorific effects in the furnace are produced, viz., the fusion of the iron and the slags, and also the chemical effects of reduction-which assumptions are erroneous: for the composition of the gases is an effect of reduction, and not a cause. The reasoning in the context, moreover, is, that the fixed oxygen in the ore has to be made to enter into combination with the.fixed carbon in the coke, and that therefore, because it has been found "practically" that when a mixture of ore and carbon is exposed in a close retort to the heat of the furnace, it is necessary to supply a large amount of heat in order to bring about a combination of the elements-which is no doubt true-it is calculated that for the reduction of the peroxide of iron, there is an excess of heat absorbed requiring as much as 3'19 cwts. of carbon to compensate it. This is a conclusion at variance with the direct experiments quoted in detail, p. 49, showing that there is very nearly a balance between the heat developed by burning CO to CO2 in the process of reduction, and the heat absorbed in effecting the reduction, that is, in effecting the disengagement of the oxygen from the iron in the ores. Then again the specific heat of iron is taken as 0'12, water being 1. This is the specific heat of bar iron at temperatures of about 250~ C. For such " temperature" as is assumed for 168 APPENDIX. the fusion of the iron (viz. 2223~ C. or 4000~ F.), the specific heat of pig-iron is quite problematical. If such a degree of temperature as 2200~ C. exists in the hearth, the specific heat of the molten iron would be 0'22 (see Table 6, Note VI., Appendix). And further, the specific heat of slags is taken as 0-20, but the specific heat at the temperature assumed in the calculations in question, 4000~ F. = 2223 C., would be 0-40, according to the experiments and calculations of M. Schinz. Thus, admitting the principle of the calculation as to caloric required for fusion of iron and slags, the factors used are so arbitrarily chosen, that the results have no acceodance with direct experiment, no scientific accuracy, no practical value. That a result something near what might be expected is finally obtained, is only an illustration of Mr. Canning's sarcastic remark, "that anything can be proved by figures." This too is the place to notice some criticisms of Mr. Bell's conclusions as to the use and abuse of a superheated blast. On the theoretical opposition to Mr. Bell's conclusions, nothing need be said. However, a paper entitled "' Further Results from the use of Hot Blast Firebrick Stoves" contains two tables of the working of two Consett furnaces examined by Mr. Bell, from which tables of results conclusions are drawn, which an examination of them without preconceived notions does not justify. At the bottom of one table (No. IV. Furnace) is written: Decrease of temperature, 200o. Increase of coke per ton, 213 lbs. and at the bottom of the other (No. V. Furnace): Mean decrease of temperature, 200o. Mean increase of coke per ton, 169 lbs. Now, taking the period of working at the blast temperatures of APPENDIX. 169 cwts. qrs. lbs. 1400~ F. = 763~ C., the mean consumption of coke is 17 3 6 12000 F. = 6500 C., the consumption.. 18 1 19 Therefore the increased consumption for loss of 200~ 0 2 15 or 71 lbs.-exactly ~ of the estimate stated. Again, the difference of consumption of coke when working at 1400~ F. varies, so that the greatest difference is 123 lbs., or nearly double the difference for a fall of 200~ F. The difference between the greatest consumption at 1400~ and the consumption at 1200~ is only 67 lbs. The difference when the furnace is working with blast at 12000, and at 1190~, or a fall of 10~0, is 194 lbs. coke, or 2-7 times as great as for a fall of 200~. For the same temperature of blast, viz., 1148~ at two periods, the difference was 82 lbs. of coke, or more than for the fall from 1400~ to 1200~. For No. V. Furnace the facts are: For the furnace working at blast temperatures of 1450~ F. = 788 C., the difference at one period and another is 90 lbs. Working at 1260~ F., or a fall of 190~ F., the difference is 128 lbs. (in favor of hot blast). cwt. qrs. lbs. Again, the mean consumption at 1450~ = 19 3 25 cc" " " 1250 =-21 1 21 1 2 24 =- 192 lbs. Thus in the one furnace a fall of 10~ increases the consumption by 194 lbs., and in the other a fall of 200~ increases it by 192 lbs. If we take into consideration the very great variations in weight of blast at the time one "consumption" was taken and 170 APPENDIX. that at the other, the difference of yield from one period to the other, and from one furnace to the other, the conclusion drawn from these extracts from the books of the Consett Company as to the greater economy of a blast at 760~ C. and the one at 650~ C. cannot be accepted as proving that there is any necessary connection between the difference of consumption of coke, and it is only by selecting results that the difference of 2 Cent. increases for the decrease of temperature of 200~ F. = 160 C. can be made out for particular weeks of working. Upon the value of such deductions from "facts" as this paper contains, the following quotation from section xxxii. of Mr. Bell's work gives a practical iron-master's estimate: " There is nothing easier than to persuade ourselves that this or the other furnace is doing better or worse than some other with which it is compared, or in comparing the same furnace at different periods. In such an inquiry it is absolutely indispensable that all disturbing causes should be eliminated, and every instance brought down to one common level in respect to the coke, ironstone, and limestone consumed, temperature of the blast, and every other circumstance connected with its working." The opinion to which all the evidence of fact and calculation leads appears to me to be, that it is more economical to get the necessary caloric by a good design of the furnace than by a superheated blast. Reverting further to Mr. Bell's work, it is of some importance to state here the values of the factors of calorific effects, used by Mr. Bell and M. Gruner respectively, in the calculation of the caloric necessary for, or absorbed in, the production of ironl; and to make the subject more distinct, the APPENDIX. 171 weight of materials per ton of iron yielded, of Mr. Bell's example, Section xli., p. 374, are used. Mr. Bell's M. Gruner's Factors. Materials, Calories. Factors. Calories. Tons. Reduction of Fe203 of iron. 1780 0-93 1665 1887 1750 Reduc. of P205, SO3 and SiO.2 170... 170 210 210 Fusion of Pig Iron.. 330 1 00 330 330 330. Fusion of Slags...... 550 1 396 770 550 770,Decomposition of Limestone. 370 0-55 202 373.5 203 Decomp. of H20 in Blast per lb. 3400 0-0025 85 3222 80 Carbon Impregnation.... 2400 0 003 72 0 0 Decomp. of C02 in Limestone 3200 0-066 206 0 0 Transmission through walls of furnace, twyre, water, etc.. 270... 270 270 270 Expansion of Blast.... 185 0 0 3955 3613 Thus, there are three sources of absorption which together involve 463 calories per lb. of iron produced, which Mr. Bell deems it necessary to take into calculation, and which M. Gruner does not. The question of the decomposition of C02 in limestone has been referred to above. The "Expansion of the Blast" introduces an element of guess-work for which it is difficult to find a reason. Upon the final balance of accounts Mr. Bell has 337 calories more than M. Gruner for this special case-a difference of 8'5 %. On the other hand, for the caloric evolved on the supposition that C02 = 0'783 (p. 378), M. Gruner is agreed with Mr. Bell on the principle of calculation for every element but one, viz., the effect of the C02 of the limestone. 172 APPENDIX. Mr. Bell reckons M. Gruner reckons C in CO of Gases.. 1322 C in CO of Gases.. 1322 13'22 Less that in Limestone 1 32 1190 C in CO2 of Gases.. 6'58 C in CO2 of Gases.... 6-58 Less that in Limestone 1'32 5 26 Total C in Gases.. 1848 Total...... 1848 And reducing both to one unit we have C. Cals. C. Cals. C in CO 0'595 X 2473 = 1465 0'661 X 2473 = 1635 C in C02 0'329 X 8080 = 2660 0'263 X 8080 = 2135 4125 3770 Thus, M. Gruner's estimate of the heat evolved is 8 % less than Mr. Bell's, arising from difference of appreciation of the function of the CO2 of the limestone in the blast furnace. As to the sensible heat carried off in the gases, the estimates would be the same, viz., 430 of the lb. units. As to the caloric carried in by the blast, or rather as to the balance of calories for heating the blast, the calculations give 253 calories in the one and 278 in the other, or the temperature of blast would have to be 220~ in the one case and 240~ in the other. But the true principles of calorific determinations are so exhaustively displayed in M. Gruner's Studies, that I must refer those who desire to familiarize themselves with these principles and their applications to that source of information, and especially to sections 4 and 16 to 21. Before concluding this note, however, let us examine one case to illustrate the necessity of attending to all the "vital statistics" of furnaces before drawing any conclusions as to their technical economy. APPENDIX. 173 Let us take for example Clarence furnace 1866 and Consett No. 4. ANALYSIS OF TECHINICAL ECONOMY, ETC. Clarence. Consett, Ratios. Remarks. Height in feet.... 80 55 1 to 145 Capacity in cubic feet... 11500 10300 1 to 1-115 Ore per ton Iron yielded... 2-440 2'083 Iron 41 % to Limestone do.... 0-683 0'406 48 * Ratio of total to smelt Ash in Coke....... 0088 0'076 to 1.total carbon = Total raw material to smelt. 3-211 2565 128 to 1* Pig-iron yielded in 24 h.. 38'6 60 1r55 to 1 C t Carbon burned at Cutbiefeet capacity per ton.. 300 171 1X75 to 1 Twyres, or for smelting, plus that due to Weight of Blast, tons... 5'193 3-75 greater amount of Weight of Gases.... 6-933 5-161 [ caloric carried in, Total Coke, tons... 1-115 0 900 comes to within 45 ~Total Cokerb t ~ons 115~ 0'~9090 I~p. c. of the ratiolIto 1, Total Carbon. 0'990 0-789 1 126 to 1* compared with total Carbon burned at Twyres 9.. 3 0930 0675 1'37 to 1I weight smelted. Temperature of Blast.. 4850 7180 Caloric carried in by Blast, cals. 602 643 1 to 1'07t r The caloric carried Temperature of Gases. 3320 2480 off is as nearly as ~Temperature of Gases...332~248 o I may be in the ratio Caloric carried off by Gases, cals. 545 303 1-80 to 1 I of the carbon conCarbon burned in Zone of Re- lurnvedforreduction. duction...... 0-058 0113 1 to 1'95 This table shows that in a technical point of view there is no practical difference in the economy of working in the two furnaces. The greater yield of the Consett furnace is another question. The rate of driving, calculated by the capacity of furnace per ton of yield, is as 1'75 for Consett against 1 at Clarence. Why one furnace can be driven faster than another is as yet unexplained. At Cleveland the pressure of the blast was 2'75 lbs. as at Consett, but the area of the twyres at Consett was 80 square inches, while at Clarence it was 50. 80 is to 50 as 1'60 to 1, but it would require 80 to 46, to give the ratio of faster driving, viz., 1'75 to 1. This is a subject well worthy the attention of iron-masters and their managers. It will not be without interest to mention here, in reference 174 APPENDIX. to the economy of fuel in blast furnaces, that the recorded consumption of coal per ton of forge iron produced has been, at the Dowlais Ironworks, as given on the authority of the late Mr. Truran by Dr. Percy, and as given by Mr. Menelaus, the present manager of these vast works, as follows:In 1791. 1831. 1862. In Furnace.. 6tons. 6 cwt. 0 qrs. 2 10 0 1 8 0 For Engine.. 1 15 0 0 10 0 0 0 0 Calcining.. 0 6 0 0 6 0 0 5 0 Total Coal.. 9 7 0 3 6 0 113 0 or of Coke.. 6 5 0 2 4 0 1 2 0 or of Carbon..5 10 0 1 19 0 0 19 1 12 lbs. Or in three successive generations as 5: 2:1. Again, let us call to mind that Carbon. Consett No. 4 furnace works with.. 5'78 cwt. with 48 % ores. Clarence....... 198 40 " Pousin (capacity 4080 ft.).194 41 " Consett No. 5.... 200 48 " Osnabriick (Georg-Marienhutte) (C 8040) 25'5 24 1' These are a few illustrations to prove that the minimum quantity of fuel required can only be determined approximately for each particular case, of which all the vital statistics are known. Capacity, height, temperature of blast, are all subordinate to desin f furnace, quality of material, and skill iU management. The history of the hot blast-the different apparatus for applying it-its effects on the progress of iron manufactureand its theory, I feel reluctantly obliged to reserve for further consideration. APPENDIX. 175 NOTE VI.-USEFUL TABLES AND MEMORANDA FOR CALCULATIONS OF BLAST FURNACE PHENOMENA. 1. Chemical Equivalents, etc. e'. B1n' v;' 1 Composition of Air. Substances. E: i e I t By Volume. By Weight. Carbon... C 6 12...... Air O+ N. O+N Oxygen.. 0 8 16 1'108... "... Nitrogen... N 14 14 0'969... 20196 79'24 -28331 76-68 Phosphorus. P 31 31... 177 or in,, Silicon... Si 14 21...... round Hydrogen. H 1 2 0H0694... numSulphur... S 2 32 2.216* 2-03 bers Calcium... Ca 20 40... 1*58 21 79 23 77 Aluminium. Al 13-7 2755.. 2A67_ Iron.. Fe or Fe2 28 56... 7-79 Carbonic Oxide CO 14 28 0969 Weight of cubic metre of " Acid. C02 22 44 11524... air, 1 300 kilo. Water.... HO or H20 9 18... 1-00 Weight of cubic foot = Silica. Si 02 30 37... 2-65 lb= Phosphoric Acid P2 05 102 142 cubic feet of dry air. Alumina... Al12 03 79 103... 390 cAir in winter contains Calcia or Lime. Ca 0 48 56 about *0000342 lbs. per Limestone (pure) CaO CO2 70 100... 2-72 cubic foot, or, 0w00495 lbs. per lb. of dry air. * as vapor. FOR C AND 0. Equiv. Weight. Per cent. Volume. Sp. gr. C 12 or 6 42'86 Carbon Vapor 1 0'82922 0 16 or 8 57-14 Oxygen Gas 1 1'10563 C() 28 or 14 100'00 Carbonic Oxide 2 1-93485 1 Equiv. Carbonic oxide = CO = 14.. 1 096742 FOR CO2. Equiv. Weight. Per cent. C 12 or 6 27'27 Carbon Vapor () 1 0-82922 20 32 or 16 72-73 Oxygen Gas 2 2-21126 44 or 22 100-00 2 3'04048 Regnault, [1 Equivalent C02=O 22.] 1 1'52024 1'52910 176 APPENDIX. FOR IRON ORES. The natural combinations of iron with oxygen are, 1. Suboxide of iron and Fe O 4 with 7g'4 % iron. peroxide Fe J 2. Oxide of iron or peroxide Fe2 03 with 70,o iron. 3. Hydrated oxide of iron Fe2 09 with Gt % iron. 4. Carbonate of protoxide Fe C03 with 48'3 %O iron. 2. Caloric. —Determination of Caloric of Combustion. CARBON. 1 lb. CO to C02= 2403 calories by experiment. 1 lb. C to C02=8080 do. do. 1 lb. carbon-gives * lbs. CO.... CO burned gives I X 2403 = 5607. Hence, for the combustion of I lb. C to CO we have 8080-5607=2473 calories by calculation. IRON. Cals. 1 lb. iron burned to Fe3 O4 (magnetic oxide) gives 1648, Dulong.. Fe203=1854 "' " " 1575, Pouillet,.. " =1775 " " " 1582, Andrews, " =1780 4' to FeO (protoxide)=1352 Favre and Silbermann, " =2028 7437 The mean of which experiments and calculation... =1859 Number adopted by M. Gruner is 1887 Mr. Bell, 1780 THERMOMETERS. 90 Fahrenheit = 50 Centigrade = 40 Reaumur. Temperature Fahrenheit = _ Temp. Cent. + 32 9 Reau. + 32 4 Temperature Centigrade= 5 (Temp. Fahr. - 32)= 65 Temp. Reau. 6 APPENDIX. 177 QUANTITIES OF HEAT are expressed in units of weights of water heated one degree, or in pounds of water heated one degree of Fahrenheit (the British unit); or in kilogrammes of water, one degree of Centigrade (the French unit); or, as in this translation, in pounds of water raised one degree Centigrade. One Centigrade unit of heat equals 1 8 Fahrenheit units for same unit of weight of water. THERMOMETRIC PYROMETER SCALES. Supposing we have determined the Freezing Point and Boiling Point of thermometers or pyrometers of iron, glass, copper, and platina, these thermometers show at 3000, by the air thermometer or true temperature, as follows:Air. Platina. Copper. Glass. Iron. 300. 312. 329. 353. 373. How vague, therefore, must be thermometric units as determined for higher temperatures still! 3. Melting Points, Latent Heat, etc. 1. EXPERIMENTS OF PERSON. Specific Heat. Melting-point Latent Heat. Degrees. C. Latent Het. Solid. Fluid. Tin.... 237'7 0'0562 0'0637 14"25 Bismuth... 266 8 0'0308 0'0363 12 64 Lead.... 3262 00314 0 0402 5-37 Zinc... 415'0 0'0955... 28'13 Daniell. Pouillet. Gold... 1250 1102 Silver... 1100 1023 IRON. Pouillet. Plattner. Blast Furnace Slags. English Hammered. 16000. Platter. Soft, French... 1500 Temperature of Melting point of Steel, best..1400 Formation of Slags when Steel....... 1300 Slag. formed. Gray Pig-iron. 1200 1530 C. White Pig-iron... 1050 1876 C. 14450 C. 12 178 APPENDIX. Mitscherlich ( Chemie, vol. i. p. 289) reckons the melting point of platinum at under 1560~ C.; and if this be a true deduction, then certainly the melting points of gold, silver, iron, etc., as above given, are too high. There is no certainty in these melting points being exact. 4. Specific Heats of Gases, Water = 1. Equal Equal Weights. Volumes. Atmospheric Air.. 0 2377 0-2377 These numbers for equal volumes are so Oxygen..... 02182 0-2412 nearly the same that it seems highly Hydrogen. 04046 0 2356 probable that for permanent gases the Nitrogen.. 02440 02370 J specific heat of equal volumes is the Carbonic Oxide. 02479 02399 ame-Regaut Carbonic Acid.. 0-2164 0'3308 Steam... 0'4750 0'2950 5. Specific Heats of Solids. The specific heat of bodies varies with the specific gravity. ThusRegnault found Charcoal... 02415 Coal.... 0-2009 Diamond... 0-1469 Dulong and Petit found that the specific heat varies with the temperature. Mean Specific Heat. Substances. Between 00 and 1000. Between 00 and 300~. Iron- (rod).......... 01098 0-1218 Zinc............ 00927 0'1015 Silver........... 00557 0'0611 Platinum........... 00335 0'0355 Glass.......... 0'177 0'190 The specific heat varies from the solid state to the fluid. ThusSolid. Fused 350~ to 4500. Lead.. 0314 0-402 APPENDIX, 179 6. Schinz's Experimental Results on Specific Heats. Specific Specific Gravities. lbs. per Heat Increase for C. Ft. at 1000. each 1000. IRON. Gray Foundry Iron. 635 7'275 471 mean 0'09049 0'00399 Light Gray.. 6916 7572 495 White and "Spiegel" 7.056 7'889 502 0'08937 0'00635 Steel (Cementation) 7 400 7'825 522...... Cast Steel. 826 8'092...... Bar Iron.. 352 7'912... 0'1190... Wire.... 7794 8'100...... Coke... 1120... 75 0'1571 0'0194 ORES. Calcareous Iron Ore.. 503... 168 0 2557 Red Spathose, raw.. 3679. 249 0'11174 0 084 4" 4 calcined. 4413... 296 0'153006 0'013 White Spathose, raw. 3555... 242 0-12478 0'045 4" calcined 4460... 305 0'17955 0'008 Clay Iron Stone, raw. 3238... 218 0'1894 0,0033 calcined 3829... 256 0'17632 0'0141 Magnetic Ore.... 4220... 284 0'16674 0'0071 Limestone, uncalcined. 2525.. 172..... 4" 4 calcined. 2 075... 140 Blast Furnace Slags.. 2383... 160 0'1469 0'010 Do. do. 2 917... 195 0'1479 0'0116 Do. do. 2 777... 156 0'1492 0'0117 Do. Hayange. 2-573... 176 0-14698 0-0125 Memorandum. —Average weight, per cubic foot, of the materials of the charges, as they are filled into the charging barrows at Clarence Works:Coke..'218 cent. =24-5 lbs. = ~ of theoretical or solid. Calcined Ore.'678 " =76'5 " " Limestone'607 " -68 "," Memorandum.-If a weight m ot a substance be heated to temperature t', and plunged in a weight m of water, raising the temperature thereof by t degrees, then a, the specific heat, is determined by the equation mt Sm't'=-mt. 8. s t mt,' From this equation we have also t"_ = t. sm/n' For example, a platina ball, of 200 grains weight, heated in a furnace, 180 APPENDIX. plunged into a weight of water of 1000 grains, raises the temperature of the water by 70; then m = 1000 - m = 200t =7 - s (spec. heat of platina) - 0-0355 (?) 1000X7 7000 t1_lOO- 7 - 9760C. 200X 0355 7-1 Here the supposition is made that the sp. heat of piatina is the same at 976o as at 300; but, supposing the difference for the first 2000, viz., 0'002 or for 100~ =0 001 to contain these at 976, or say 9000, we should have 0 001 X (900 - 300) =0'006. Then 00:355+ 0 006 =0 0415, 1000 x 7 7000 and therefore 000 7__ 7000 — 8540c 200 X 0061 8-2 a difference of 1220. The most recent experiments are those of Professor Wanhold of Chemnitz, and from these, made with every precaution to insure accuracy, the specific heat of platinum may be taken for pyrometric work as constant. INDE X. ACTION proper of blast furnace, Bell, I. Lowthian, on decrease of 160-162 oxygen and carbon in the Agreement of the formulas with the gases of the blast furnace, complete analysis, 38-42 158, 159, 160 Air, composition of, 175 on the action proper of blast determination of the mass of, furnace, 160-164 blown through the twyres, 37, On the Development and Ap38 plication of Heat in Iron of blast, weight of, 60 Blast Furnaces, 156 weight of, in blast, 65, 68, 72, 75 theory of the blast furnace, Alfreton furnace, 157 140 Analysis and formulas, agreement of, Berthier on waste gases, 145 38-42 Big furnaces, yield of, 21, 22 application of new method, to a Blast, caloric carried in by, 61 French blast furnace, 118-121 consideration of weight of; 169 of gases, 45 furnace, action proper of, 160-164 of technical economy, 172 calorific phenomena of, 156 Andrews, Prof., experiments, 147 determination of the caloric Application of new method of analysis received by, 56 to a French blast furnace, 118-121 experiments of M. Schinz on, Askam-in-Furness, furnace, 23 148-152 Aubertot, M., application of waste phenomena, tables, and megases by, 145 moranda for calculating, Aubuisson, 38 175-180 Austria, height of blast furnaces in, 18 theory of, 140-174 furnaces, determination of the caloric consumed in, 46-47 BALANCE of raw material and of principal reactions in, 24-26:) yield of blast furnace of Pouzin, recent modifications in, 17 122-128 successive enlargements of, Barrow, furnaces at, 23 18 Bell, I. Lowthian, 17, 21, 22, 23, 26 influence of highly heated, 10129, 39, 42, 48, 49, 51, 55, 116 59, 67, 85, 86, 91, 93, 94, influence of variations of the 95, 131, 136, 138, 139, 150 temperature of, 101 160 weight of air in, 65, 68, 72, 75 and M. Gruner, 170, 171, 172 Boulanger and Dulait's experiments experiments on the chemical on the heat in pig-iron, 51 and physical phenomena Budd, James P., patent for applicaof the blast furnace, 152 tion of heat, flames, and gases of importance of his investiga- the blast furnace to heating hottions, 165 blast stoves, 145, 146 on caloric of slags, 53 Bunsen's experiments on the comporequired in iron smelt- sition of gases of the furnace, 143, ing, 165-174 144, 146 12* 182 INDEX. Bunsen and Playfair on the gases Clarence furnace, economy of fuel at, evolved from iron furnaces, 157, 158 174 furnaces compared with French furnaces, 130 CALORIC absorbed and given off in works, 91, 92, 93 blast furnaces, 26-29 examples of working of, 63 by the fusion of the slag and 64, 67, 78, 79 the decomposition of the furnaces of, 19, 21 limestone, 52-54 gases of the furnaces at, 39, by the reduction of the ores 40 and the fusion of the pig- Cleveland, furnaces in, 19, 20, 33 iron, 47-52 hearths of, 130 in the reduction of ores, prior to 1860, 23 fluxes, etc., 49, 50 highest furnace, temperature of of peroxide of iron, 48 escaping gases at, 104 arising from the oxidation of Coke and charcoal, decomposition of, silicium, phosphorus, etc., 49 139 carried in by blast, 61, 65, 68, 72, Consett furnace, economy of fuel at, 75 174 off by radiation from walls fuel used at, 174 of furnace, 131 furnaces at, 23 off by the gases, 63 conclusions drawn from reconsumed in blast furnaces, 46-47 sults at, 111 determination of, received by a examples of working of, 70, blast furnace, 56 73, 78, 79, 104, 105, 106, lost by radiation from the walls 109, 111, 114, 115 of furnace, etc., 55, 56 table of results of actual of combustion, determination of, compared with hypothetic 176 working, 111 more economical to get, by a working of, 168, 174 good design of furnace than by use of superheated blast at, 103, an over-heated blast, 115 104 produced in the furnace, 61, 65, Cowper-Siemens and Whitwell's 69, 72, 75 stoves of fire-brick, 17 required in iron-smelting, 165174 taken for reduction of the ores, 62 ]EBRAY, M., experiments of, 26 Calorific effects, factors of, 170, 171, Decomposition of limestone, 63 172 Denain, blast furnaces of, 128 efficiency of the furnace, index Despretz, experiments of, 49 to, 166 Determination of the caloric conphenomena of the blast furnace, sumed in blast furnaces, 156 46, 47 Calculations of blast furnace phe- received by a blast furnace, nomena, 175-180 56 Capacity, great, influence of, 88-93 Deville, H., and Cailletet, experiCarbon and iron, 176 ments of, 25 deposition, 164. r Diameters of furnaces, 17 impregnation, 163 Dowlais Ironworks, economy of fuel Carbonic acid, 96 a. at, 174 oxide, dissociation of, 162 Driving furnace, rate of, 173 Charcoal and coke, decomposition of, Dry gases, weight of, 60 139 Dulait and Boulanger's experiments Charging French furnaces, 130 on slags, 53 Chemical equivalents, 175 Dulong's experiments on the gases, Clarence furnace, blast at, 173 144, 146 INDEX. 183 FARTHY metals, caloric corre- Furnace, application of the new mesponding to, 49 thod of analysis to a French, Ebelmen, analyses of, 88 118-121 on analysis of the gases at Sera- caloric produced in, 64, 65, 69 ing, 42 elements of the working of, 121, on comparison of fuels, 139 122 Ebelmen's experience of slow work- of Montluqon, 129 ing, 86, 87, 88 theory of, 140-174 experiments on the composition of Vienne in the Isere, 86 of blast furnace gases, 144, Furnaces, after a certain height has 146 been attained, no longer any Economy, analysis of, 172 advantage in enlarging, 101 maximum, how obtained, 115 at Pont-Eveque, 86 Economical working of the furnaces, big, yield of, 21, 22 how it varies, 29-33 economical working of, how it England, furnaces in, 18 varies, 29-33 hearth too wide in, 130 French, manner of charging, 130 Escaping gases, weight and compo- section of, 130 sition of, 34-38 large and small, 81 Eston Works, 91 measure or index of the working large furnaces of, 92 of, 33, 34 Equivalents, chemical, 175 reduction of height of, 23 Experiments on the heat in pig-iron, synoptical table of results ob50, 51 tained in the working of various, 78 Fusion of slag, caloric absorbed by, FACTORS of calorific effects, 170, 52-54 171, 172 of slags, 63 Favre and Silbermann, 48 and Silbermann's experiments, 147 / ASEOUS current in furnaces, 24 on the caloric absorbed. of blast furnaces, 93 in the decomposition currents of blast furnaces, comof limestone, 54 position of, 135 Ferruginous carbon, 96, 97 Gases, analysis of, 45 Ferryhill furnace, temperatures of at Seraing, 42 escaping gases at, 104 beyond a certain height, the furnaces at, 20, 21 temperature of, does not diFormulas and analysis, agreement of, minish by reason of dissocia38-42 tion of oxide of carbon, 93French blast furnaces, 118-131 101 furnaces, manner of charging, caloric carried off by the, 63 130 determination of the mean temsection of, 130 perature of, 45 Fresenius, M., analysis of Spiegel escaping from the furhace, 154 iron, 154 weight and composition of, Fuel, comparison of, 139 34-38 consumption of, in the ideal evolved from iron furnaces, Bunworking blast furnace, 140 sen and Playfair on, 157, 158 economy of, 174 in the economical working of natural limit of the economy of, furnaces, 29 140 method of taking specimens of, required, 174 42-46 used at various furnaces, 174 of blast furnace, Bunsen's expeFurnace, advantage of good design riments on the composition of, of, 115 143, 144 184 INDEX. Gases of blast furnace, Dr. Percy on Large furnaces, 101 analysis of, 147 Latent heat, 177 Ebelmen's experiments Leichtfliissig, 136, 187 on the composition of, Le Play, M., on the reducing power 144, 146 of carbonic oxide, 142 of the furnaces at Clarence works, Limestone, caloric absorbed by de39, 40 composition of, 52-54 sensible heat carried off by, 54, decomposition of, 63 55 CO,. rt specific heat of, 178 waste of, furnace, 145 M EASURE or index of the workweight of dry, 60 M ing of blast furnaces, 33, 34 weights of, 64, 68, 71, 74 Melting points, 177 Gillot's experiments on slags, 53 Method of taking specimens securing on the heat in pig-iron, 51 a mean of gases, 42-46 Gjers, J., account of development of Minary and RWsal's experiments on Cleveland furnaces, 20 slags, 52 Gmelin, L., Hand Book of Chemistry, on the heat in pig-iron, 146 51 Great height and capacity, influence Modifications in blast furnaces, 17 of, 88-93 Montluqon, furnace in, 129 Gruner, M., and I. L. Bell, 170, 171, 172 NEWPORT, furnaces at, 19, 22 Norton, furnaces at, 20 HEARTH too wide in England, 130 Heat, quantities of, 177 Height of furnaces, 17 RORES, fluxes, etc., caloric absorbed fHighly heated blast, influence of, J in the reduction of, 49, 50 101-116 refractory, 136 Hot-blast stoves, heating, 146 Ormesby furnace, 91 examples of working of, 67, 78, 79 DEAL working, 105 of 1867 compared with of the furnace, 28, 30, 31, French, 130 32, 38 monster furnace at, 20 Influence of extra-slow working, Osnabrfick furnace, fuel used at, 174 86-88 Oxide of iron, reduction of, 95 of great height and capacity, Oxygen and carbon, decrease of, in 88-93 blast furnace, 158, 159, 160 of highly heated blast, 101-116 supplied to the gases of the furIron and Steel Institute of Great nace, 106 Britain, 17 ores, equivalents for, 176 -smelting, caloric required, 165- DERCY. Dr., examination of figures 174 I of Bunsen and Playfair on gases, 158, 159 Metallurgy of Iron and Steel, J[ARSTEN, 38 importance of, 147 fiX on the theory of the blast fur- on analysis of blast furnace gases, nace, 141, 142, 143 147 on comparison of fuels, 139 on composition of gaseous curLAMPADIUS, W. A., on the rents, 135 theory of the blast furnace, 140, on melting points of metals and 143, 147, 153 alloys, 138 INDEX. 185 Peroxide of iron, caloric absorbed in Sefstr6m and Berthier experiments reduction of, 48 on silicates, 52 Plattner's experiments on fusibilty of Sensible heat carried off by the gases, slags, 52 54, 55 on slags, 136, 138 Seraing, Ebelmen on the analysis of Phosphorus, oxidation of, 49 the gases at, 42 Pig-iron, composition of, 35 Silicates, 137 experiments on the heat in, fusibility of, 52 50, 51 Silicium, caloric produced by the Pont-Eveque, furnace at, 86 oxidation of, 49 Pouzin, blast furnaces of, 120-128 Slags, 136-138 Pouzin furnace, fuel used at, 174 fusibility of, 52, 53 Principal reactions in blast furnaces, fusion of, 63 24-26 formation of, 136, 137 Protoxide of iron, 97 Slow-working, influence of extra, 86-88 Solid descending current in furnaces, QUANTITIES of caloric absorbed 24 and given off in blast furnaces, Spathore iron, 97 26-29 Specific heat, 177 heats of gases, 178 of solids, 178 RADIATION, caloric lost by, 55, Sclhinz's experiments, 179 56 St. Jacques' Works, 129 from walls of furnace, 131 Stoves of fire-brick, Cowper-Siemens Raw material and yield of blast fur- and Whitwell's, 17 nace of Pouzin, 122-128 Strengfluissige, 136, 137 Reactions in blast furnaces, 24-26 erzen, 138 Recent modifications in the regime of Styrian and Carinthian furnaces, blast furnaces, 17 yield of; 138 Reduction in the blast furnace, 25, 26 Successive enlargements of blast furof ores and fusion of pig-iron, naces, 18-24 caloric absorbed by, 47-52 Superheated blast, 103 Refractory ores, 136 excess of caloric carried in slags, 137 by, 103 Region of fusion, Tunner's experi- Sweden, height of blast furnaces in, 18 ments on temperatures of, 131 Synoptical table of results, 78 Regnault, 54, 55 found at Consett, 111 Rinman's experiments on slags, 53, 54 on the heat in pig-iron, 51 Russia, height of blast furnaces in, 18 TABLE of results, 78, 111 1 found at Consett, 111 Tables and memoranda for calculaAMUELSON, Mr., on monster tions of blast furnace phenomena, furnaces, 93 175-180 Scheurer-Kestner and Ch. Meunier Teague, Moses, patent for utilization on the products of combustion of of waste gases, 145 coal, 42 Technical economy, analysis, 172 Schinz, M., 162, 168 Tees-side, furnace, 19, 20 experiments of, on the calorific Temperature, influence of variations phenomena of the blast furnace, of, in the blast, 101 148-152 of blast and at the tunnel-head, Schinz's experiments on specific 104 heats, 179 Thermometers, 176 Scotland, furnaces in, 18 Thermometric pyrometer scales, 177 Section of French furnaces, 130 Theory of the blast furnace, 140-174 186 INDEX. Thornaby, furnaces at, 19 Weight of air in blast, 65, 68, 72, 75 Troost and Hautefuille, experiments of blast, 60 of, 49 of the dry gases, 60 Tunner's experiments on the ternm- Weights of gases, 64, 78, 71, 74 peratures of region of fusion, 131 Weislarch, 38 Welther, law of, 48 Williams, Ed., of Eston Works, ATHAIRE'S experiment on the quoted, 91 heat in pig-iron, 51 Workington, furnaces at, 23 experiments on slag, 53 Vienne, furnace at, 86 YIELD and raw material of blast l furnace of Pouzin, 122-128 ilyALES, furnaces in, 18 W~ Wedding, Dr., on composition of gases, 135 7ONES of reaction in the furnace, Weight and composition of the escap-L Bell's examination of, 153 ng gases, 34-38 / -) -f -ne O 02' -R- - T~-'+y' -"o z tv ( ('8 Bt~ij A - KrciQS bt t t ~ 1- -lo J 4. \ \ 4h ~3~S \XN W 0\Q -At tS? n~~~~~~~~~~~~4 zet7g0'Js- ~;~ ( t ~~? rrrrS~i~ O +- -~~M3-~~e ~g,,\ -i~- YY'ii~ t8% 2 ')(df~l 0 l3 " b'oo.',?i omnia,,f 7,, I " r.,-Q If p. a~ rhlf. 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A complete detailed description of the various Materials and Apparatus used in the Perfumer's Art, with thorough Practical Instruction and careful Formulae, and advice for the fabrication of all known preparations of the day, including Essences, Tinctures, Extracts, Spirits, Waters, Vinegars, Pomades, Powders, Paints, Oils, Emulsions, Cosmetics, Infusions, Pastiiles, Tooth Powders and Washes, Cachous, Hair Dyes, Sachets, Essential Oils, Flavoring Extracts, etc.; and full details for making and manipulating Fancy Toilet Soaps, Shaving Creams, etc., by new and improved methods. With an Appendix giving hints and advice for making and fermenting Domestic Wines, Cordials, Liquors, Candies, Jellies, Syrups, Colors, etc., and for Perfuming and Flavoring Segars, Snuff and Tobacco, and Miscellaneous Receipts for various useful Analogous Articles. By R. S. CRISTIANI, Consuiting Chemist and Perfumer, Philadelphia. 8vo.. $5.00 DAVIDSON.-A Practical Manual of House Painting, Graining, Marbling, and Sign-Writing: Containing full information on the processes of House Painting in Oil and Distemper, the Formation of Letters and Practice of SignWriting, the Principles of Decorative Art, a Course of Elementary Drawing for House Painters, Writers, etc., and a Collection of Useful Receipts. With nine colored illustrations of Woods and Marbles, and numerous wood engravings. By ELLIS A. DAVIDSON. I2mo. $3-00 ZAVIES.-A Treatise on Earthy and Other Minerals and Mining: By D. C. DAVIES, F. G. S., Mining Engineer, etc. Illustrated bh76 Engravings. 2mo. $5.00 tro HENRY CAREY BAIRD & CO.'S CATALOGUE. DAVIES.-A Treatise on Metalliferous Minerals and Mining: By D. C. DAVIES, F. G. S., Mining Engineer, Examiner of Mines, Quarries and Collieries. 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Illustrated by fourteen folding plates and several wood engravings. 743 PP. 8vo. 8vo. $Io oo DUSSA OCE.-Practical Treatise on the Fabrication of Matches, Gun Cotton, and Fulminating Powder. By Professor H. DUSSAUcE. I2mo..$3 00 DYER AND COLOR-MAKER'S COMPANION: Containing upwards of two hundred Receipts for making Colors, on the most approved principles, for all the various styles and fabrics now in existence; with the Scouring Process, and plain Directions for Preparing, Washing-off, and Finishing the Goods. I2mo. $I 25 EDWARDS.-A Catechism of the Marine Steam-Engine, For the use of Engineers, Firemen, and Mechanics. A Practical Work for Practical Men. By EMORY EDWARDS, Mechanical Engineer. Illustrated by sixty-three Engravings, including examples of the most modern Engines. Third edition, thoroughly revised, with much additional matter. I2mo. 4I4 pages... $2 o00 EDWARDS.-Modern American Locomotive Engines, Their Design, Construction and Management. By EMORY EDWARDS, Illustrated 12mo..........oo EDWARDS.-The American Steam Engineer: Theoretical and Practical, with examples of the latest and most approved American practice in the design and construction of Steam Engines and Boilers. For the use of engineers, machinists, boilermakers, and engineering students. By EMORY EDWARDS. Fully Plustrated, 419 pages. I2mo.. e d $2.50 1 HENRY CAREY BAIRD & CO.'S CATALOGUE. EDWARDS.-Modern American Marine Engines, Boilers, and Screw Propellers, Their Design and Construction. Showing the Present Practice of the most Eminent Engineers and Marine Engine Builders inl the United States. Illustrated by 30 large and elaborate plates. 4to. $5.oa EDWARDS.-The Practical Steam Engineer's Guide In the Design, Construction, and Management of American Stationary, Portable, and Steam Fire-Engines, Steam Pumps, Boilers, Injectors,;overnors, Indicators, Pistons and Rings, Safety Valves and Stealn Gaufes. For the use of Engineers, Firemen, and Steam Users. By EMORY EDWARDS. Illustrated by II9 engravings. 420 pages. I 211o...$2 50 EISSLER.-The Metallurgy of Gold: A Practical Treatise on the Metallurgical Treatment of Gold-Bearing Ores, including the Processes of Concentration and Chlorination, and the Assaying, Melting, and Refining of Gold. By M. EISSLER. With go Illustrations. I88 pp. I211.. $3 00 ELDER.-Conversations on the Principal Subjects of Politick' Economy. By Dr. WILLIAM ELDER. 8vo. $2 5C ELDER.-Questions of the Day, Economic and Social. By Dr. WILLIAM ELDER. 8VO.. $3 00 ELDER.-Memoir of Henry C. Carey. Py Dr. WILLIAM ELDER. 8vo. cloth. 75 ERNI.-Mineralogy Simplified. Easy Methods of Determining and Classifying Minerals, including Ores, by means of the Blowl ipe, and by Humid Chemical Analysis, based on Professor von K(jbell's Tables for the Det-'minationl of Minerals, with an Introduction to Modern Chemistry. By HENRY ERNI, A.M., M.D., Professor of Chemistry. Second Edition, rewritten, enlarced and improved. I2mo.... 3oc FAIRBAIRN.-The Principles of Mechanism and Machineiy of Transmission ~ Comprising the Principles of Mechanism, Wheels, and Pulleys, Strength and Proportions of Shafts, Coupling of Shafts, and Engaging and Disengaging Gear. By SIR WILLIAM I'AIRBAIRN, Bait. C. E. Beautifully illustrated by over 50o wood-cuts. In one volume, 12mo. $2.5C FLEMING.-Narrow Gauge Railways in America. A Sketch of their Rise, Progress, and Success. Valuable Statistics as to Grades, Curves, Weight of Rall, Locomotives, Cars, etc. BIy HOWARD FLEMIN(G. Illustrated, 8vo. $I o3 FORSYTH.-Book of Designs for Headstones, Mural, and other Monuments: Containing 78 Designs. By JAMES FORSYTH. With an Introduction',v CHARLES BOUTELL, M. 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X2mo...75 GEE.-The Silversmith's Handbook: Containing full instructions for the Alloying and Working of Silver, including the different modes of Refining and Melting the Metal; its Solders; the Preparation of Imitation Alloys; Methods of Manipulation; Prevention of Waste; Instructions for Improving and Finishing the Surface of the Work; together with other Useful Information and Memoranda. By GEORGE E. GEE, Jeweller. Illustrated. I2mo. I.75 GOTHIC ALBUM FOR CABINET-MAKERS: Designs for Gothic Furniture. Twenty-three plates. Oblong $2.00 GREENWOOD.-Steel and Iron: Comprising the Practice and Theory of the Several Methods Pursued in their Manufacture, and of their Treatment in the RollingMills, the Forge, and the Foundry. By WILLIAM HENRY GREENWOOD, F. C. S. Asso. M. I. C. E., M. I. MW. E., Associate of the Royal School of Mines. With 97 Diagrams, 536 pages. I2mo.. $2.00 GREGORY.-Mathematics for Practical Men: Adapted to the Pursuits of Surveyors, Architects, Mechanics, and Civil Engineers. By OLINTHUS GREGORY. 8vo., plates. $3.0O GRIER.-Rural Hydraulics: A Practical Treatise on Rural Household Water Supply. Giving a full description of Springs and Wells, of Pumps and Hydraulic Ram, with Instructions in Cistern Building, Laying of Pipes, etc. By W. W. GRIER. Illustrated 8vo. 75 GRIMSHAW. —Modern Milling: Being the substance of two addresses delivered by request, at the Franklin Institute, Philadelphia, January i9th and January 27th, I88i. By ROBERT GRIMSHAW, Ph. D. Edited from the Phono. graphic Reports. With 28 Illustrations. 8vo. DRIMSHAW.-Saws: The History, Development, Action, Classification, and Comparison of Saws of all kinds. With Copious Appendices. Giving the details 14 HIENRY CAREY BAIRD & CO.'S CATALOGUE. of Manufacture, Filing, Setting, Gumming, etc. Care and Use ot Saws; Tables of Gauges; Capacities of Saw-Mills; List of Saw. Patents, and other valuable information. By ROBERT GRIMSHAW, Second and greatly enlarged edition, with Supplement, and 354 Illustrations. Quarto.$4.oc GRIMSHAW.-A Supplement to Grimshaw on Saws: Containing additional practical matter, more especially relating to the Forms of Saw-Teeth, for special material and conditions, and to the Behavior of Saws under particular conditions. I20 Illustrations. By ROBERT GRTMSHAW. Quarto G3RISWOLD.-Railroad Engineer's Pocket Companion for the Field: Comprising Rules for Calculating Deflection Distances and Angles, Tangential Distances and Angles, and all Necessary Tables f6r En. gineers; also the Art of Levelling from Preliminary Survey to the Construction of Railroads, intended Expressly for the Young Engineer, together with Numerous Valuable Rules and Examples. By W. GRISWOLD. I2mo., tucks. $175 GRIUNER. Studies of Blast Furnace Phenomena: By M. L. GRUNER, President of the General Council of Mines of France, and lately Professor of Metallurgy at the Ecole des Mines. Translated, with the author's sanction, with an Appendix, by L. D. B. GORDON, F. R. S. E., F. G. S. 8vo..2.SC Hand-Book of Useful Tables for the Lumberman, Farmer and Mechanic: Containing Accurate Tables of Logs Reduced to Inch Board Meas, ure, Plank, Scantling and Timber Measure; Wages and Rent, by Week or Month; Capacity of Granaries, Bins and Cisterns; Land Measure, Interest Tables, with Directions for Finding the Interest on any sum at 4, 5, 6, 7 and 8 per cent., and many other Useful Tables. 32 mo., boards. I86 pages..25 HASERICK.-The Secrets of the Art of Dyeing Wool, Cotton,,and Linen, Including Bleaching and Coloring Wool and Cotton Hosiery and Random Yarns. A Treatise based on Economy and Practice. By E. C. HASERICK. illustrated by 323 Dyed Patterns of the Yarnj or Fabrics. 8vo. $I2.5c HATS AND FELTING: A Practical Treatise on their Manufacture. 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Illustrated by ninety engravings. 8vo. $4.00 WARN.-The Sheet-Metal Worker's Instructor: For Zinc, Sheet-Iron, Copper, and Tin-Plate Workers, etc. Containing a selection of Geometrical Problems; also, Practical and Simple Rules for Describing the various Patterns required in the different branches of the above Trades. By REUBEN H. WARN, Practicai Tin-Plate Worker. To which is added an Appendix, containing Instructions for Boiler-Making, Mensuration of Surfaces and Solids, Rules for Calculating the Weights of different Figures of Iron and Steel, Tables of the Weights of Iron, Steel, etc. Illustrated by thirtytwo Plates and thirty-seven Wood Engravings. 8vo. $3.00 WARNER.-New Theorems, Tables, and Diagrams, for the Computation of Earth-work: Designed for the use of Engineers in Preliminary and Final Estimates, of Students in Engineering, and of Contractors and other non-profes. sional Computers. In two parts, with an Appendix. Part I. A Practical Treatise; Part II. 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WATSON, Author of " The Modern Practice of American Machinists and Engineers." Illustrated by 78 engravings. $1.50 WATSON.-The Modern Practice of American Machinists and Engineers: Including the Construction, Application, and Use of Drills. Lathe Tools, Cutters for Boring Cylinders, and Hollow-work generally, with the most Economical Speed for the same; the Results verified by Actual Practice at the Lathe, the'Vise, and on the Floor. Together HENRY CAREY BAIRD & CO.'S CATALOGUE. 29 with Workshop Management, Economy of Manufacture, the Steam Engine, Boilers, Gears, Belting, etc., etc. By EGBERT P. WATSON. Illustrated by eighty-six engravings. I2mo... 2.56 WATSON.-The Theory and Practice of the Art of Weaving by Hand and Power: With Calculations and Tables for the Use of those connected with the Trade. By JOHN WATSON, Manufacturer and Practical Machine. Maker. Illustrated by large Drawings of the best Power Looms. 8vo. ~...... $7.50 WATT. —The Art of Soap Making: A Practical HIand-book of the Manufactlme of Hard and Soft Soaps, Toilet Soaps, etc., including many New Processes, and a Chapter on the Recovery of Glycerine from Waste Leys. By ALEXANDER WATT. 11. I 2mo. $3.oo WEATHERLY.-Treatise on the Art of Boiling Sugar, Crystallizing, Lozenge-making, Comfits, Gumn Goods, And other processes for Confectionery, etc., in which are explained, in an easy and familiar mallner, the various Methods of Manufactur. ing every Description of Raw and Refined Sugar Goods, as sold by Confectioners and others. I2mo... I.5 WIGHTWICK.-Hints to Young Architects: Comprising Advice to those who, while yet at school, are destined to the Profession; to such as, having passed their pupilage, are about to travel; and to those who, having completed their education, are about to practise. Together with a Model Specification involvir,g a great variety of instructive and suggestive matter. By GEORGE W!GHTWICK, Architect. A new edition, revised and considerablly enlarged; comprising Treatises on the Principles of Constructi,;n and Design. By G. HUSKISSON GUILLAUME, Architect. Numerous Illustrations. One vol. I2mo.... 2.00 WILL.-Tables of Qualitative Chemical Analysis. With an Introductory Chapter on the Course of Analysis. By Pro-.ssor IIEINRICH WILL, of Giessen, Germany. Third American, from the eleventh German edition. Edited by CHARLES F. HIMES, Ph. D., Professor of Natural Science, Dickinson College, Carlisle, Pa. 8vo... $1.50 WILLIAMS.-On Heat and Steam: Embracing New Views of Vaporization, Condensation, and Explo. sion. By CHARLES WYE WILLIAMS, A. I. C. E. Illustrated 8vo. $3 50 WILSON.-A Treatise on Steam Boilers: Their Strength, Construction, and Economical Working. By ROBERT WILSON. Illustrated I2mo. $2.5c WILSON.-First Principles of Political Economy: With Reference to Statesmanship and the Progress of Civilization. By Professor W. I). WILSON, of the Cornell University. A new and revised edition. I2iio. $I.50 30 HENRY CAREY BAIRD & CO.'S CATALOGUE. WOHLER.-A Hand-Book of Mineral Analysis: By F. WoHLER, Professor of Chemistry in the University of G6ttingen. Edited by HENRY B. NASON, Professor of Chemistry in the Renssalaer Polytechnic Institute, Troy, New York. Illustrated. I2mo.......... $.00 WORSSAM.-On Mechanical Saws: From the Transactions of the Society of Engineers, I869. By S. W. WORSSAM, JR. Illustrated by eighteen large plates. 8vo. $2.50 RECENT ADDITIONS. ANDERSON.-The Prospector's Hand-Book: A Guide for the Prospector and Traveler in Search of Metal Bearing or other Valuable Minerals. By J. WV. ANDERSON. 52 Illustrations. I2mo. $...........50 BEAUMONT.-Woollen and Worsted Cloth Manufacture: Being a Practical Treatise for the use of all persons employed in the manipulation of Textile Fabrics. By ROBERT BEAUMONT, M. S. A. With over 200 illustrations, including Sketches of Machinery, Designs, Clothls, etc. 39I PP. I2mo. $2.5G BRANNT.-The Metallic Alloys: A Practical Guide for the Manufacture of all kinds of Alloys, Analgams and Solders used by Metal Workers, especially by Bell Founders, Bronze Workers, Tinsmiths, Gold and Silver Workers, Dentists, etc., etc., as well as their Chemical and Physical Properties. Edited chiefly from the German of A. Krupp and Andreas Wildberger. with additions by WM. T. BRANNT. Illustrated. I2mo. $2.50 CROSS.-The Cotton Yarn Spinner: Showing how the Preparation should be arranged for Differen Counts of Yarns by a System more uniform than has hitherto been practiced; by having a Standard Schedule from which we make all our Changes. By RICHARD CROSS. 122 pp. I2mo.. 75 GRANT.-A Hand-Book on the Teeth of Gears: Their Curves, Properties, and Practical Construction. By GEORGE B. GRANT. Illustrated. Second Edition, enlarged. 8vo. $S.oo MAKINS.-A Manual of Metallurgy: By GEORGE IIOGARTH MAKINS, M. R. C. S., S. C. S. Illustrated by Ioo engravings. Second edition rewritten and much enlarged. 8vo., 592 pages. $ o HENRY CAREY BAIRD & CO.'S CATALOGUE. 31 POSSELT.-Technology of Textile Design: Being a Practical Treatise on the Construction and Application of Weaves for all Textile Fabrics, with minute reference to the latest Inventions for Weaving. Containing also an Appendix, showing the Analysis and giving the Calculations necessary for the Manufacture of the various Textile Fabrics. By E. A. POSSELT, Head Master Textile Department, Pennsylvania Museum and School of Industiial Art, Philadelphia, with over Iooo illustrations. 292 pages. 4to..5.oo POSSELT.-The Jacquard Machine Analysed and Explained: With an Appendix on the Preparation of Jacquard Cards, and Practical Hints to Learners of Jacquard Designing. By E. A. POSSELT. With 230 illustrations and numerous diagrams. 127 pp. 4to......... $3.00 ROPER.-Instructions and Suggestions for Engineers and Firemen: By STEPHEN ROPER, Engineer.$2.00 ROPER.-The Steam Boiler: Its Care and Management: By STEPHEN ROPER, Engineer. 12mo., tuck, gilt edges. $2.00 ROPER.-The Young Engineer's Own Book: Containing an Explanation of the Principle and Theories on which the Steam Engine as a Prime Mover is Based. By STEPHEN ROPER, Engineer. I6o illustrations, 363 pages. I8mo., tuck. $3.00 ROSE.-Modern Steam-Engines: An Elementary Treatise upon the Steam-Engine, written in Plain language; for Use in the Workshop as well as in the Drawing Office. Giving Full IExplanations of the C)onstruction of Modern SteamEngines: Including Diagrams showing their Actual operation. Together with Complete but Simple Explanations of the operations of Various Kinds of Valves, Valve Motions, and Link Motions, etc., thereby Enabling the Ordinary Engineer to Clearly Understand the Principles Involved in their Construction and Use, and to Plot out their Movements upon the Drawing Board. By JOSHUA ROSE, MI. E. Illustrated by 422 engravings. 4to, 320 pages.. $6.oo POSE.-Steam Boilers: A Practical Tteatise on Boiler Construction and Examination, for the Use of Practical Boiler Makers, Boiler Users, and Inspectors; and eml*acing!n plain figures all the calculations necessary in Designing or Classifying Steam Boilers. By JOSHUA ROSE, M. E. Illustrated by 73 engravings. 250 pages. 8vo. $2.50 SULZ.-A Treatise on Beverages: Or the Complete Practical Bottler. Full instructions for Laboratory Work, with Original Practical Recipes for all kinds of Carbonated Drinks, Mineral Waters, Flavorings, Extracts, Syrups, etc. By CHAS. HERMAN SULZ, Technical Chemist and Practical Bottler. Illustrated by 428 Engravings. 8I8 pp. 8vo... $Io.oo 32 HENRY CAREY BAIRD & CO.'S CATALOGUE. Davis.-A Practical Treatise on the Manufacture of Bricks, Tiles, Terra-Cotta, etc.: Including, Hand-Made, Dry Clay, Tempered Clay, Soft-Mud, and Stiff-Clay Bricks, also Front, Hand-Pressed, SteamPressed, Re-Pressed, Ornamentally Shaped and Enamelled Bricks, Drain Tiles, Straight and Curved Sewer and WaterPipes, Fire-Clays, Fire-Bricks, Glass Pots, Terra-Cotta, Roofing Tiles, Flooring Tiles, Art Tiles, Mosaic Plates, and Imitation of Intarsia or Inlaid Surfaces, comprising every Important Product of Clay Employed in Architecture, Engineering, the Blast Furnace, for Retorts, etc., with a History and the Actual Processes in Handling, Disintegrating, Tempering and Moulding the Clay into the Shape, Drying Naturally and Artificially, Setting, Burning with Coal, Natural Gas and Crude Oil Fuels, Enamelling in Polychromic Colors, Composition and Application of Glazes, etc., including Full Detailed Descriptions of the Most Modern Machines, Tools, Kilns and Kiln Roofs used. By CHARLES THOMAS DAVIS. Second Edition. Thoroughly Revised. Illustrated by 217 Engravings. 501 pp. 8vo. $5 00 CONTENTS.-CHAPTER I. The History of Bricks. II. General Remarks Concerning Bricks, their Size, Strength and Other Qualities, Ornamental Bricks, Architectural Terra-Cotta, Blue Bricks, Saltpetre Exudations upon Brick-Work. III. Enamelling, Glazing and Ornamenting Bricks and Tiles, Earthenware, etc. IV. Selecting Clays for Various Kinds of Bricks-The Different Varieties of Clay-The Characteristics, Qualities and Localities-How to Color Bricks Red-Kaolin-TerraCotta Clays-Fire Clays-Exploring, Digging and Marketing Fire Clays -Washing Clays. V. Making and Burning a Kiln of Hand-Made Bricks. VI. Manutacture of Dry Clay Bricks. VII. The Manufacture of Tempered-Clay Bricks, Including a Description of the most Modern Machinery Employed. VIII. Kilns. [X. The Manufacture of Pressed and Ornamental Bricks. X. The Manufacture of Fire-Bricks. XI. The Manufacture of Drain Tiles. XII. The Manufacture of Sewer-Pipes. XIII. The Manufacture of Roofing Tiles. XIV. The Manufacture of Architectural Terra-Cotta. XV. Ornamental Tiles, etc. Index.