The intention is to prevent a needless loss of capital in improvements not likely to be beneficial either to the stockholders or the public. From the Mechanics' Magazine. ON THE USES OF ZINC FOR ROOFING OF in mountains there are always gentle de-dressed to Taylor & Son, Henderson, Ky., civities met with, which (when gained by will meet with prompt attention. an ascension of a lock, or two, as the case Knowing that a Railway from Charleston may be) can be easily graded, and at a to Cincinnati is in contemplation, and antriffing expense, comparatively speaking; ticipating a meeting of Commissioners and whereas, by making inclined planes, those Engineers sometime this spring, I have All well enough, but we see from the gentle ascents are lost by being merged in been induced to make this communication, manner in which they handle Railroads, the general inclination; 4thly, it will enable in order that the subject might undergo a that they are much behind us, not only in you to dispense with the use of stationary timely consideration, as it may be the engines, (which will be found to be no small means of causing a survey of more direct regard to the experience, but as to their geitem,) as the machinery of the locks will routes, and also be a great saving of ex-neral views of the subject-inmany instanalways be propelled by the locomotives, pense in the making and keeping up the ces we think most singularly inaccurate. without requiring them to be detached from road. I have not been at home since the 4th the train of cars, the whole train being of Nov., and am quite ignorant of what is elevated at the same time with the locomo-going on upon the subject of the road. tive; whereas, on inclined planes, the lo- The United States Frigate Potomac, of comotives are always detached from the 1600 tons burthen, was raised by the screw train, and if there be many cars, they are dock in New-York, 22 feet in the space of brought up in detached parcels, thereby oc-40 minutes. There were 90 men at work casioning a delay of time; 5thly, the use to propel the screws. The weight of that of locks will enable you to do the business vessel is supposed to be equal to 1000 or 1200 with a less number of locomotives, as the tons. Now, if it were necessary that such same locomotive will carry the cars through a vessel should be raised daily, or even the whole road, without requiring to be de-weekly, there is no doubt, but that it would tached from the cars; whereas, the locomo- have been constructed so as to be propelled tives in the use of inclined planes, are al- by steam. This I think is a clear and satisways stopped at the end of the plane, and factory proof of the practicability of the must there remain until a returning train lock. will require its use; and lastly, there is not the slightest danger to be apprehended in ascending or descending by locks, whereas there is always great danger to be apprehended in passing inclined planes. think enough has already been said to show that locks are decidedly preferable to inclined planes, provided their practicability can be shown, (or proved,) and I soldiers. RAILROAD AND CANAL FOREIGN. AND ON THE PRODUCTS FORMED BY EXPO- Metallic zinc has been applied to various uses in the Arts in Europe, since 1740 or 1750. Though it had been known and wrought for a long time previous by the Chinese and East Indians. The abundance and cheapness of this metal, early attracted the attention of speculators to employ it in the useful arts, and it is stated in the Philosophical Transactions for 1747, that it casts and bores quite as well as brass, and it is proposed that it this can clearly be done by mathematical of 1000 florins each, in the Iron Railroad to should be used for various culinary vessels calculations. I have gone into the calculations, and proven it to my entire satisfaction as to power, &c. The plan of this important machinery has been derived from the screw docks, the ability of which to elevate weight to an almost incalculable extent is When the Messrs. Rothschild deal so not to be doubted, as sufficient tests of its largly in Railroad stocks, it is a fair prepowers have already been given in New-sumption that the investment is a good York and Baltimore. The only difference between the two machines is, that the lock by its peculiar construction, is capable of being connected with and propelled by the locomotives, which being placed in the lock, with their train of cars, may be instantly attached to the machinery of the lock, and which being put in motion, elevates itself one. The Swabian Mercury announces that Messrs. Rothschild have taken 4000 shares, be established between Galicia and some other points of the Austrian States. The as a substitute for iron and other metals, works of this road will be begun in the that were then, and still continue in use spring, and will be executed by about 30,000 for such purposes. The use of this metal for culinary vessels, attempted to be made, both in England and France, was of short duration, for it was soon ascertained that the various acids that are contained in a considerable proportion of our articles used as a vegetable diet, act upon the A most important application of the Jac-zinc, and that the compounds formed from quard loom has just been made. It is now the union of the metal with these acids, being used in raising figures on bed-quilts. are both disgusting to the taste, and The figures are in relief on the surface of poisonous. Besides, it is found that the the cloth, and are as firmly bound as on metal is rapidly acted upon, by contact counterpanes made the usual way. The in- with moist air, or alternate wetting and tion is gained by means of screws, the Spection of a 13-4ths quilt, just finished, drying, and that when corroded, it is soluble has given great satisfaction. The effect on the prices of these articles will be astonish-in water, (as we shall state when speaking ing. A quilt, 13-4ths, by the Jacquard of the oxide of zinc,) forming a very deleloom, may be had raw for 18s.; whilst one terious solution, and rendering the water made in the usual manner costs 30s. in wholly unfit for ordinary domestic purposes. wages only. [Herald.] Within a few years an attempt has been Much useful information as to the sur-made to introduce the use of this metal for prising improvement of these looms will be found in the evidence before the Select Committee of the House of Commons. and the cars at the same time. The eleva same as those of the dock. The screws of the dock are propelled by the application of manual labor, whereas those of the lock are propelled by means of machinery, and that by steam. It is confidently believed that locks may be made to ascend and descend thirty feet in the space of five minutes from the time the locomotive is attached to it. Mr. Taylor has given me an estimate of the expense of a lock of 130 feet in length, say sufficient to elevate a locomotive and ten produce cars, the whole weight of which, together with that of the cradle on which they stand, may be considered equal to 160 tons, to be raised thirty feet; this he says will be readily done by an engine of M. Bernet, an engineer at Lyons, has ininvented a machine he calls a Balayeuse, by which, with the employment of only one horse, the mud in the streets, squares, and highways, is collected and thrown into a cart with extraordinary regularity, giving horse power. The expenses, agreea-100 strokes on a surface of about six yards bly to this estimate, will be $8135; but in square, and thus doing the work of 200 order to make the estimate safe, he added in the same space of time. $1865 for contingences, making a total of We wish some engineer in New-York $10,000. Mr. Taylor has had a brass model of the machinery made, which he will ex- would invent and put into operation a Balhibit at any time when called on, and I ayeuse, he certainly would not come into think will be fully able to dispel all doubts bad odor. on the subject, Auy communication ad *Here the figures denoting the quantity of horse power are defaced by the seal, Scavengers Much debate is going on in the House of Commons on the subject of Railroads, particularly those in and near London. culinary vessels into the United States, and it was especially recommended as having the peculiar property of preserving the sweetness of milk for a much longer time than the materials generally used for such purposes, but unfortunately the anticipations were not verified in the trials, and the use of the metal for such purposes is now almost totally abandoned. if exposed to a warm atmosphere, soon If milk be kept in a zinc vessel, it will, begin to undergo a change. An acid is formed, which attacks the metal vessel and dissolves a portion of it, forming a salt which is both disagreeable to the taste, and deleterious to the system. The metal cannot, therefore, ever be used for the above pur pose with safety. More recently, it has been proposed to use the metal for covering the roofs of build, ings, as a substitute for slate, copper, and other materials, that have been for a long time in general use; and unfortunately for the public, large sums have already been expended for zinc roofs, which is worse than useless, when we take into consideration the trouble and expense of removing the material, and supplying its place with some other. One could hardly see how it is possible that the public should be so deccived in the use of an article that has been so thoroughly tried and condemned, both in France and England. From the London Mechanics' Magazine. Nothing is perhaps more certain than ferwise, the use of rain water which runs the fact, that this metal can never be used from it must be partially or entirely disconadvantageously for covering roofs. In the tinued. first place, the expansion of the metal is so great by slight changes of temperature, that the junctures are exceeding liable to get out of place from expansion and contraction, hence in the present manner of thing of this kind? putting on the metal, the buildings are constantly liable to leak. In the second place, the metal is very brittle, so that two sheets cannot be put together by folding, but must be joined in a sort of double coil, thus: EMBOSSING ON WOOD. declare that it would supersede carving and marily expensive nature of the machinery, and the jealousy of cabinet-makers, who inlaying, and so spoil their business. The will be brought out in different colors; it is process may be so varied that the relief also applicable to the embossing of cloths, kerseymeres, waist-coat pieces, paper-hangings, and things of a like nature. Sir, I have been shown some very beautiful specimens of embossing upon veneer, principally floral and arabesque designs, upon rosewood, maple, mahogany, elm, and other hard woods. The relief is almost alto, and has quite the appearance of carving. I understand the invention is patented, but that the inventor, M. Caccia, And though this roof, when new, will shedness in the open air, it takes fire and burns rain tolerably well, it can never be made with intense brilliancy, forming an exceeding it into extensive operation from the prian Italian, has been prevented from bringto resist the action of melting snow, as has ingly light, white substance, which is a a considerable number of our citizens, during the oxygen of the air. It is therefore an been proved to the satisfaction, I trust, of compound of the metal with a portion of the past winter. The reason of the leak- oxide of zinc, and generally denominated age is quite evident to any one who has the flowers of zinc. This is the only comstudied the principles of capillary attrac-pound of zinc and oxygen described in most tion and the laws of fluids. Suppose, for of the books; it is a white powder so light example, that a roof covered with zinc con-as readily to float in the atmosphere, and tains a depth of six inches of snow, and is perfectly insoluble in water. that the snow melts rapidly and becomes If zinc be exposed to moist atmosphere, saturated with water to the depth of three it becomes covered with a gray coating, This is the first instance, as far as I inches this would have precisely the same which is described as a mixture of the know, in which designs have been impresseffect in proving the roof as if its whole white oxide and the metal ; but ed upon wood-embossing is common as the gray surface were actually covered with water compound is soluble in water, and neither enough upon card, paper, calico, and such to the same depth. The capillary attrac- of the others possess the same property, the fabrics; and unless there be some imtion exerted by the water in the small opinion advanced in the books can hardly provement in the process, I do not know spaces between the coils, together with the be correct. Berzelius, who first described that the patent will hold good. Making weight of a column of water three inches the gray compound, considers it as a sub-the parts in relief come up of different in depth upon the same, is sufficient to al- oxide, though he does not mention the fact colors, I believe to be new; and upon this low water enough to pass through any that it is soluble in water. This last pro- possibly the patent rests. roof thus covered to inundate the building. perty is one that renders the metal highly It will be seen that the above objections objectionable as a roofing, for the sub-oxide apply equally to all metal roofs put together formed by the action of alternate wet and in the same manner. If we would keep dry weather, is dissolved off by the rains, our buildings dry, the snow must not be and carried into the cisterns, deteriorating allowed to accumulate on them, or the metal the water, and rendering it almost entirely used to cover the roofs must be made water unfit for all domestic purposes. It thus actight by soldering. The past winter has quires a styplic, coppery taste, and if taken tested, in the severest manner, roofing ma- into the stomach, produces nausea and voterials; heavy snows, followed by heavy miting. It decomposes soap, and produces rains and rapid thaws, have continually that property in water called hardness, alternated during the whole season, and which renders it unfit for washing. the damage done to buildings, furniture, and goods, will be felt for a long time. The brittleness of zinc renders it highly objectionable. This property is increased in a tenfold proportion, by diminishing its temperature. At the freezing point of water it is almost as brittle as glass; and hence if any heavy body fall upon the coils which project above the roof, they are very liable to be broken, and when broken it is exceedingly difficult to repair them. Embossed hard fancy woods might be very extensively and very beautifully applied to the ornamenting of cabinets, workboxes, &c., and to the panels of doors and wainscoting. Herewith I send you some specimens, that in the effect produced, you may judge for yourself. November, 1835. I am, &c. P. B. T. From the London Mechanic's Magazine. REMARKS ON THE CONSTRUCTION OF BOG-ROADS. In the first case, they run on the crown of the road, consequently in the same rut; and as the traffic increases, the rut becomes greater. If the water which has dissolved the sub-oxide of zinc be freely exposed to the air, oxygen will be absorbed, and the suboxide will be gradually converted into the white oxide or flowers of zinc, which being Sir,-There are some instances where insoluble in water, falls to the bottom as vehicles are obliged to run in the same fast as formed in the state of a white pow-track or rut, either owing to the sloping der, and thus the water at length becomes sides of a road, its inequality, or to facilinearly pure again. This effect is quite tate the journey of the horses on account of perceptible after a dry season, when the its being boggy. water constantly becomes better, until it is again deteriorated by a fresh fall of rain, which dissolves more of the metal. Now, since rain water is so valuable an article in all large towns and cities, any agent that would deteriorate it must be got rid of, even if it be at a considerable expense. Be sides, rain water, after being filtered through sand and charcoal, is now coming into use for drinking, and substituted for the spring water, which has been formerly universally used for this and for all culinary purposes. There are two distinct compounds form- It is, therefore, quite certain, that the use of ed by exposing to the action of the air this zinc as a roofing for dwelling houses, at metal. If the metal be heated to white-east, must be entirely abandoned, or oth The third objection to the use of zinc for roofing is, that it is dissolved in the water which runs over the roof, and thus renders it unfit for all domestic purposes. This fact seems to be one that has not yet attracted the attention of the public. Having unfortunately resided under a zinc roof, and shared largely in its deleterious effects, I have been led to examine the qualities communicated to the water by means of the zinc. The inequalities of a road are a great evil; and when the road is boggy as well, the sides are still more avoided, as the water in running over the sloping sides is absorbed in the yielding substance, and renders passage over them impossible. Ruts cease to exist if the roads are worn equally in every part; therefore, if the roads are perfectly level, or nearly flat, every ve hicle will take a separate track. The first thing to be considered in the construction of bog-roads, after the ground is well drain. ed, is the making the surface perfectly level; || invention was first put into operation, ob-be well enough conceived from the sectionand after that has been effected, if concrete, tained full and free access to all informational sketch on the margin. similar to what is used in securing the regarding the results of trials of the inven- The whole of the materials put into the foundations of buildings, and mixed with tions in those works, on the large scale of furnace, resolved themselves into gaseous broken stone, were thrown in, and exposed manufacture, I cannot help thinking that an products, and into liquid products. The for a considerable time, it would be supe-authentic notice of these results, together gaseous products, escaping invisible at the rior to any other method previously adopt- with an attempt to explain the cause of top, included all the carbonaceous matter of ed. When hardened sufficiently for con- them, will prove acceptable to the Royal the coke, probably in the form of carbonic stant use and friction, time alone would Society of Edinburgh. And that these re-acid, except only the small portion of carsoon prove whether it would not be more sults, as well as the cause of them, may be bon retained by the cast-iron. The liquid serviceable and efficacious than either the set forth with clearness, I shall advert products were collected in the cylindrical method of "laying branches of trees on the 1st. To the process of making iron, as reservoir, constituting the bottom of the level of the strata," or "firm heathy sods." formerly practised. furnace, and there divided themselves into When such roads are situated near any two portions, the lower and heavier being place from whence lime may be obtained, the melted cast-iron, and the upper and or gravel could be had in abundance, addi- 3d. To the effect of that alteration. lighter being the melted slag, resulting from tional facilities would be offered for effect- 4th. To the cause of that effect. the action of the fixed portion of the flux ing this method, which, as it becomes by I. In proceeding to advert to the process upon the fixed impurities of the fuel and of exposure as firm as a rock, would certainly of making cast-iron, as formerly practised, the ore. be found beneficial. The additional ex-it cannot here be necessary to enter into pense attending the construction of such a much detail in explanation of a process, road, if the work is properly performed, long practised and extensively known, as would also be compensated by the perma- this has been; nor, indeed, shall I enter nent and substantial road which would be into detail, farther than, to the general the result. Yours, &c. scientific reader, may be proper to eluciFREDERICK LUSH. date Mr. Neilson's invention. Charles-square, Hoxton, Nov. 20, 1835. [Some useful hints as to the improvement of our common roads, in similar situations, may be drawn from the foregoing article.-ED. M. M.] ge 2d. To Mr. Neilson's alteration on that process. In making cast-iron, then, the materials made use of were three The ore, The flux. The ore was clay iron-stone, that is to say, carbonate of iron, mixed, in variable proportions, with carbonates of lime, and of magnesia, as well as with aluminous and siliceous matter. II. Thus much being understood in regard to the process of making cast-iron, as formerly practised, we are now prepared for the statement of Mr. Neilson's improvement. This improvement consists essentially in heating the air in its passage from the blowing apparatus to the furnace. The heating has hitherto been effected by mak ing the air pass through cast-iron vessels, kept at a red heat. In the specification of the patent, Mr. Neilson states, that no particular form of heating apparatus is essential to obtaining the beneficial effect of his invention; and, out of many forms that have been tried, experience does not seem to have yet decided which is best. At The fuel made use of at Clyde Iron Clyde Iron Works, the most beneficial of Works, and in Scotland generally, was the results that I shall have occasion to coke, derived from splint coal. During its state, were obtained by the obvious expeconversion into coke, this coal underwent dient of keeping red-hot the cast-iron cylina loss of 55 parts in the 100, leaving 45 of drical pipes, conveying the air from the Coke. The advantage of this previous con-blowing apparatus to the furnace. version consisted in the higher temperature III. Such being the simple nature of Mr. produced by the combustion of the coke, Neilson's invention, I now proceed to state in consequence of none of the resulting heat the effect of its application. OF CHEMISTRY IN MARISCHALL COLLEGE, disappearing in the latent form, in the vapors arising from the coal, during its conversion into coke. The following article gives the best neral description we have seen of the "Application of the Hot Blast." It is well worth reading. From the London Mechanic's Magazine. BY THOMAS CLARKE, M. D., PROFESSOR ABERDEEN. (Read before the Royal Society of Edinburgh, March, 1835.) The flux was common lime-stone, which was employed to act upon the aluminous and siliceous impurities of the ore, so as to produce a mixture more easy to melt than any of the materials of which it was made up, just as an alloy of tin and lead serves as a solder, the resulting alloy being more easy to melt than either the lead or the tin apart. During the first six months of the year 1829, when all the cast-iron in Clyde Iron Works was made by means of the cold blast, a single ton of cast-iron required for fuel to reduce it, 8 tons 14 cwt. of coal, converted into coke. During the first six months of the following year, while the air was heated to near 300° Fahr., one ton of cast-iron required 5 tons 3 cwt. of coal, converted into coke. Among persons interesting themselves in the progress of British manufactures, it can scarce fail to be known, that Mr. Neilson of Glasgow, manager of the GasWorks in that city, has taken out a patent for an important improvement in the working of such furnaces as, in the language of The saving amounts to 2 tons 18 cwt. on the patent," are supplied with air by means the making of one ton of cast-iron; but of bellows, or other blowing apparatus." These three materials-the ore, the fuel, from that saving comes to be deducted the In Scotland Mr. Neilson's invention has and the flux-were put into the furnace, coals used in heating the air, which were been extensively applied to the making of near the top, in a state of mixture. The nearly 8 cwt. The nett saving thus was cast-iron, insomuch that there is only one only other material supplied was air, which 2 tons of coal on a single ton of cast-iror. Scotch iron-work where the invention is was driven into the furnace by pipes from But during that year, 1830, the air was not in use, and in that work apparatus is blowing apparatus, and it entered the fur-heated no higher than 300° Fahr. The under construction to put the invention into nace by nozzles, sometimes on two opposite great success, however, of those trials, enoperation. Apart from the obvious im- sides of the furnace, sometimes on three,couraged Mr. Dunlop, and other iron-masportance of any considerable improvement and sometimes, but rarely, on four. Theters, to try the effect of a still higher tem in the manufacture of so valuable a product air supplied in this manner, entered near perature. Nor were their expectations disas cast-iron, the invention of Mr. Neilson the bottom of the furnace, at about 40 feet appointed. The saving of coal was greatly would merit attention, were it only for the from the top, where the solid materials were increased, insomuch, that about the beginsingular extent of the improvement effected, put in. The furnace, in shape, consisted, ning of 1831, Mr. Dixon, proprietor of Ca' compared with the apparent simplicity-I at the middle part, of the frustrums of two der Iron Works, felt himself encouraged to had almost said inadequacy of the means cones, having a horizontal base common to attempt the substitution of raw coal for the employed. Having, therefore, by the libe- both, and the other and smaller ends of each coke before in use. Proceeding on the asrallity of Mr. Dunlop, proprietor of the prolonged into cylinders, which constituted certained advantages of the hot blast, the Clyde Iron Works, where Mr. Neilson's the top and bottom of the furnace, as may attempt was entirely successful; and, since that period, the use of raw coal has extended so far as to be adopted in the majority of the Scotch iron works. The temperature of the air under blast had now been raised so as to melt lead, and sometimes zinc, and therefore was above 600° Fahr., instead of being only 300°, as in the year 1830. The furnace had now become so much elevated in temperature, as to require, around the nozzle of the blow-pipes, a precaution borrowed from the finery-furnaces, wherein cast-iron is converted into malleable, but seldom or never employed where cast-iron is made by means of the cold blast. What is called the tweer, is the opening in the furnace to admit the nozzle of the blow-pipe. This opening is of a round funnel shape, tapering inwards, and it used always to have a cast-iron lining, to protect the other building materials, and to afford them support. This cast-iron lining was just a tapering tube, nearly of the shape of the blow-pipe, but large enough to admit it freely. Now, under the changes I have been describing, the temperature of the furnace became so hot near the nozzles, as to risk the melting of the cast-iron lining, which, being essential to the tweer, is itself commonly called by that name. Το prevent such an accident, an old invention, called the water-tweer, was made available. The peculiarity of this tweer consists in the cast-iron lining already described being cast hollow instead of solid, so as to contain water within, and water is kept there continually changing as it heats, by means of one pipe to admit the water cold, and another to let the water escape when heated.* fore. Tons. 111 162 IV. To attempt an explanation of the foregoing extraordinary results. Tons. Tons. In 1829, from 3 furnaces, Iron from 403 In 1830, from 3 furnaces, Iron from 376 In 1833, from 4 furnaces, 245 Iron Comparing the product of 1829 with the Works, that one furnace requires of hot product of 1833, it will be observed that air from 2,500 to 3,000 cubical feet in a the blast, in consequence of being heat-minute. I shall here assume 2,867 cubical ed, has reduced more than double the feet to be the quantity; a number that I quantity of iron. The fuel consumed in adopt for the sake of simplicity. inasmuch these two periods we cannot compare, since, as, calculated at an avoirdupois ounce and in the former coke was burned, and in the a quarter, which is the weight of a cubical latter coal. But on comparing the con- foot air at 50° Fahr., these correspond presumpt of coke in the years 1829 and 1830, cisely with 2 cwt. of air a minute, or six we find that although the product of iron in tons an hour. Two tons of solid material the latter period was increased, yet the con- an hour, put in at the top of the furnace, can sumpt of coke was rather diminished. scarce hurtfully affect the temperature of Hence the increased efficacy of the blast the furnace, at least in the hottest part of appears to be not greater than was to be ex-it, which must be far down, and where the pected, from the diminished fuel that had iron, besides being reduced to the state of become necessary to smelt a given quantity metal, is melted, and the slag too produced. of iron. When the fuel put in at the top is coal, I On the whole, then, the application of have no doubt that, before it comes to this the hot blast has caused the same fuel to far-down part of the furnace-the place of reduce three times as much iron as before, its useful activity-the coal has been enand the same blast twice as much as be-tirely coked; so that, in regard to the fuel, the new process differs from the old much The proportion of the flux required to more in appearance than in essence and reduce a given weight of the ore, has also reality. But if two tons of solid material been diminished. The amount of this di- an hour, put in at the top, are not likely to minution, and other particulars, interesting||affect the temperature of the hottest part of to practical persons, will appear on refer- the furnace, can we say the same of six ence to a tabular statement supplied by Mr. tons of air an hour, forced in at the bottom Dunlop, and printed as an appendix to this near that hottest part? The air supplied paper. Not further to dwell on such de- is intended, no doubt, and answers to suptails, I proceed to the last division of this port the combustion; but this beneficial paper, which is,effect is, in the case of the cold blast, incidentally counteracted by the cooling power of six tons of air an hour, or 2 cwt. a minSubsidiary to this attempt, it is necessary ute, which, when forced in at the ordinary to discriminate between the quantity of fuel temperature of the air, cannot be conceived consumed, and the temperature produced. otherwise than as a prodigious refrigeratory For instance, we may conceive a stove to passing through the hottest part of the furbe kept at the temperature of 500° Fahr., nace, and repressing its temperature. The and lead to be put into such a stove for the expedient of previously heating the blast purpose of being melted. Then, since the obviously removes this refrigeratory, leav melting point of lead is more than 100° high-ing the air to act in promoting combustion, er, it is evident that whatever fuel might be without robbing the combustion of any porconsumed in keeping that stove at the tem-tion of the heat it produces. perature of 500°, the fuel is all consumed Such, I conceive, is the palpable, the to no purpose, so far as regards the melting adequate, and very simple explanation of the of lead, in consequence of deficiency in the extraordinary advantages derived in the temperature. In the manufacture of cast-manufacture of cast-iron, from heating the iron likewise, experience has taught us, that air in its passage from the blowing apparaa certain temperature is required in order to tus to the furnace. During the three successive periods that work the furnace favorably, and all the fuel have been specified, the same blowing apconsumed, so as to produce any lower deparatus was in use; and not the least re-gree of temperature, is fuel consumed in markable effect of Mr. Neilson's invention, vain. And how the hot blast serves to in- The blowing-engine has a steam-cylinder has been the increased efficacy of a given crease the temperature of a blast furnace, of 40 inches diameter, and a blowing-cylinquantity of air in the production of iron. will appear on adverting to the relative der of 8 feet deep and 80 inches diameter, The furnaces at Clyde Iron Works, which weights of the solid and of the gaseous and goes 18 strokes a minute. The whole were at first three, have been increased to materials made use of in the reduction of power of the engine was exerted in blowing four, and, the blast machinery being still ron. the three furnaces, as well as in blowing the same, the following were the successive As nearly as may be, a furnace, as wrought|| the four, and in both cases there were two weekly products of iron during the peri- at Clyde Iron Works in 1833, had two tons tweers of 3 inches diameter to each furods already named, and the successive of solid materials an hour put in at the top, nace. The pressure of the blast was 2 weekly consumpt of fuel put into the fur- and this supply of two tons an hour was lb. to the square inch. The fourth furnace nace, apart from what was used in heating continued for 23 hours a-day, one half hour was put into operation after the waterevery morning, and another every evening, tweers were introduced, and the open spaces being consumed in letting off the iron made. round the blow-pipes were closed up by But the gaseous material-the hot air-luting. The engine then went less than 18 what might be the weight of it? This can strokes a minute, in consequence of the too easily be ascertained thus; I find, by com- great resistance of the materials contained paring the quantities of air consumed at in the three furnaces to the blast in its pasClyde Iron Works, and at Calder Iron sage upwards, During the first six months of the year 1833, when all these changes had been fully brought into operatien, one ton of castiron was made by means of 2 tons 54 cwt. of coal, which had not previously to be converted into coke. Adding to this 8 cwt. of coal for heating, we have 2 tons 134 cwt. of coal required to make a ton of iron; whereas, in 1829, when the cold blast was in operation, 8 tons 14 cwt. of coal had to be used. This being almost exactly three times as much, we have, from the change of the cold blast to the hot, combined with the use of coal instead of coke, three times as much iron made from any given weight of splint coal. the blast: An incidental advantage attended the adoption of the water-tweers, inasmuch as these made it practica ble to lute up the space between the blow-pipe nozzle and the tweers, and thus prevent the loss of some air that formerly escaped by that space, and kept up a bel. Jowing hiss, which, happily, is now no longer heard, Marischall College, Aberdeen, APPENDIX. Materials constituting a Charge. 5 006000 000000 1830-Coke, Roasted Ironstone, 5 1 1 16 1833-Coal, 5 3 16 Roasted Ironstone, 5 1 1829-Coke, Table showing the Weight of Cast-Iron produced, and the Average Weight of Coals made use of, in producing a ton of Cast-Iron, at Clyde Iron Works, during the years 1829, 1830, and 1833, the Blowing-engine being the same. COKE AND HEATED AIR. 1829 Weekly pro- 1830 Weekly pro- Average of T. C. Q. T. C. Q T. C. Q. C. QJ T. C. Q. Jan. 7 137 18 2 8 2 Jan. 9 375 14 148 0 6 21 16 267 Aug. 5 106 17 220022-OROOONONNONOORNOO 200022130 2878 18 0 209 19 0 Average 110 14 2 8 1 14 154 9 21 163 4 28 148 12 2 May 5 162 10 12 149 13 19 162 26 165 7 3 and flux require 1 lb. of fuel with hot air, and 2.5 lbs. require the same fuel with heated air. At Wasseralfingen, the increase of the mineral charge, when hot air is used, is 1.43 to 1, and at Riouperoux, 1.42 to 1. When iron for forging only is made, and fuel is scarce, it is thought that the hot air blast will be of but little advantage; the company who use the patent for this blast have stipulated for the Creusot furnace, not to pay for the construction of the heating apparatus, in case no real advantage is de rived from its use. In those furnaces which use the hot air blast, and where the mineral part of the charge has been increased, the charges pass less rapidly than formerly, and there are, of course, fewer charges in a given time, but so much more ore passes in the same time that the run of iron is much increased This increase is greater when the iron is made of the quality for forging than when made for casting. At Vienna, where iron of the second mentioned quality is manufactured, the daily yield has increased in the ratio of 1.22 to 1, while at Janon, where that of the first named quality is used, the ratio is 1.6 to 1. At La Voulte, they produce in twenty-four hours 8 or 9 tons of iron for forging, and it is stated that with an increase of the blast, the yield could be increased to 11 or 12 tons without injuring the quality of the iron. The greatest advantage from the hot air blast is undoubtedly to be found in the diminution in the enormous quantity of fuel (coal) used in some of the English works. The results obtained in the works of the south of France are the following. At Vienne, where they chiefly make iron for casting, they tried the Clyde form of heating apparatus, but abandoned it for that of Calder, by which they heat the air above the melting point of lead. The economy of coke USE OF THE HOT AIR has been in the ratio of 1.37 to 2.50. And From the Journal of the Franklin Institute. 1 ON THE (Translated for this Journal, by Professor A. D. Bache.) (Continued from page 199.) The following details confirm the abstract 1st. Furnaces using coke or coal. the daily yield has increased from 4 to 5 or 6 tons of iron. The daily product of the two furnaces at Janon, where Taylor's heatfor forging, by the consumption per ton of ing apparatus is used, is 8 or 9 tons of iron clude the fuel required to heat the iron. 1.20 to 1.40 of coke. This does not inEach of the three furnaces of La Voulte with the cold blast, they made but 7 to 8 turn out 9 tons of iron for forging, while, vorable circumstances. The consumption of coke is now 1.25 to 1.30 tons for each ton of iron, besides about 600 lbs. per ton, which is required to heat the blast; the for mer consumption was 2.10 to 2.30 tons of fuel for one of iron. The experiments made in France with crude coal and the hot air in the pipe for the purpose, a little way be- hot air blast are stated, in the Scottish works, tons of the best quality, under the most fafore it enters the furnace; the lead is in-as nearly 3 to 2. At Vienna, the same stantly melted. When in good working quantity of coke which was used for 1.075 order, zinc is fused (700°) in the same of ore and flux in the charge, is now used The air is heated in passing through for 1.51. At La Voulte, where the air is a series of iron pipes of small diameter, fixed heated only to 320° in the manufacture of upright in a brick oven, and kept at a red iron for forging, 1 part of coke is now used heat; the heated air entering the furnace to 2.1 parts of ore and flux. At the furby four tweers. The Condie pipes,'-so nace of Terre-Noire, 1 lb. of coke is used called from Mr. John Condie, the manager to 1.82 of the mixed ore and flux. of the Wilsonton Iron Works, and late of At Torteron, where a mixture of coke, the Calder-last much longer than the ill-(1-3) and charcoal (2-3) is used as fuel, 1 arranged heating apparatus (with pipes of lb. of the fuel is used to 2.83 lbs. of the large diameter) at the Clyde Iron Works, mixed charge, with the hot air blast. While at the furnace of Guerche, where they use and effect a much greater saving in fuel. "The raw coal when used as the fuel, the same ore, flux and fuel, but with the has the disadvantage of soon filling the fur-cold air blast, 1 lb. of the fuel is used for nace, and is also found to produce an infe- 2.98 lbs. of the mixed ore and flux. rior quality of iron, to that made by use of coke. It is, therefore, not unlikely to be soon, generally, given up." At Ancy-le-Franc, where charcoal is used, in the proportion of 2-3 oak charcoal and 1-3 of white wood, 2,1 lbs, of the orel blast, have not been conclusive in regard to With the hot air blast, 2. On the use of raw coal in smelting furnaces. The substitution of raw coal for coke is doubtless the source of the very great eco |