If a new crucible was used in commencing this comparison series, enough silicon might have been absorbed to produce this effect. This leads us to remark that on account of the variations of conditions in any series of tests, that cannot be foreseen, we must avoid drawing any but general conclusions, and these should be based upon a large number of experiments. (12) The fluidity of the melted metal. CHART 8. Our tests of fluidity are correct as far as each individual heat is concerned, but variation may be due to the heat of the metal of that particular cast when poured. Viewed in a general way, the indications are that with the white base, with almost no silicon, the aluminum has increased the fluidity; but judging from the series with the gray base we would say that combined with silicon aluminum reduced the fluidity. FLUIDITY. Our remarks in connection with shrinkage show that a sharp casting is will be too small to have much effect upon the fluidity of the metal. The fact of the iron giving sharper and more perfect castings, on account of the swell of the casting, caused by the deposition of graphite at the instant of solidification, might cause the iron to be pronounced more fluid, if judged by the appearance of the castings. No doubt the presence of varying quantities of manganese, sulphur, phosphorus and silicon, in the cast iron used, would modify the influence of aluminum, and until this is understood it may require considerable experiment to determine the amount of aluminum required, or how it shall be introduced. This hurried presentation of the remarkable effects of aluminum upon cast iron will give an idea of the great benefit which is now promised to the iron founder by the rapidly falling price of aluminum as cheapened by the electric furnace. We have already occupied all the time that was set apart for us. Following the publication of this part of the subject, we shall soon present the results of the laboratory work of Professor Mabery and Mr. Vorce, which will throw still more light upon this interesting subject. THE SECOND LAW OF THERMODYNAMICS. Ithaca, N. Y. [ABSTRACT] By Prof. R. H. THURSTON, THIS paper represents the views of its author respecting the various statements of the second law of thermodynamics given by various authors of authority. It considers the nature of a law as defined by science; compares the statements of the law to be examined, as made by many writers, and shows that they are commonly statements of simple phenomena and not of laws; and, finally, gives what is thought to be a true expression of the law which should be given place as the second law of thermodynamics, and shows in what manner it has value and where it finds application in the theories of heat-transformation and in the application of those theories and the science of thermodynamics to the operation of the heat engines. THE ECONOMICAL PRODUCTION OF CHARCOAL FOR BLAST FURNACE PURBy OLIN H. LANDRETH, Vanderbilt University, Nashville, POSES. [ABSTRACT.] THE economical production of charcoal on a scale commensurate with blast furnace needs has not received that attention and study its importance demands. Of all the charcoal produced, ninety-four per cent is used for the production of pig iron, the remaining six per cent furnishing the supply for all domestic purpose, manufacturing and the production of all metals other than iron, so that improvements or processes in charcoal manufacture to be of broad application must be applicable to blast furnace plants which are necessarily extensive. Though the ratio of production of charcoal iron to the total iron produced is decreasing, owing to the enormous increase in the output of coke and anthracite iron, the absolute amount produced is annually on the increase, since there are many purposes for which charcoal iron is essential and cannot advantageously be displaced by coke iron. Among these are the manufacture of the finer varieties of steel, the higher grades of chilling iron, malleable castings, tin plate, wire rods and for mixing with coke iron, in which it is found that the addition of a small amount of charcoal iron raises the character of the mixture for many purposes out of proportion to the amount added, so that notwithstanding the fact that it costs from $2 to $5 per ton more to produce a ton of charcoal iron than coke iron its peculiar properties maintain the demand for it, and such demand would increase and the character of manufactures would thereby be raised could its production be cheapened to admit it for those purposes for which it is desirable, but from which its price now excludes it. Fuel represents nearly one-half the cost of char coal iron, and herein lies the greatest promise of reduction of cost, particularly as the methods of charcoal making at present in general use for iron making are extremely crude and uneconomical. The only exception to this which has been widely adopted is the Pierce process invented by Dr. H. M. Pierce of Detroit, Mich., now a resident of Nashville, Tenn., whose process was devised in 1876 and has since been undergoing continued improvements and developments until now (1888) nine plants under this process are in operation in the southern and western states which aggregate in capacity over 325,000 cords of wood annually carbonized, with plants under negotiation of over 250,000 cords annual capacity. By this system the by-products preserved from the destructive distillation of the wood more than meet the expenses of manufacture, leaving the charcoal produced a clear profit. In outline the process is as follows: the charring is effected in circular, flat top, brick kilns holding fifty cords of wood each. The wood is charred by the heat produced by gas burned in a brick furnace under the kiln into and through which the products of combustion pass. The gaseous products of dry distillation of the wood pass from the kiln to condensers, where the tarry and liquid products are condensed and the gas sent back to the kiln. Thus none of the charcoal produced is burned to carbonize other wood as in the common pits or ovens. The gas which elsewhere is wasted is here not only sufficient to effect the carbonizing of the wood but furnishes fuel for the boilers required about the works. The wood used is as thoroughly seasoned as the conditions of maintaining a year's supply in advance, cost of storage room and interest on capital invested in stock render economical. All the common varieties in the localities of the various plants are used. The proportions of the varieties used at Nashville are approximately: If not thoroughly dry when placed in the kilns, the carbonization of the wood is automatically deferred, by the absorption of the heat in the evaporation of the sap and other moisture, until the seasoning process is complete. This seasoning commences at the top of the kilns and proceeds regularly downward, by a definite plane of seasoning. When this plane reaches the bottom and the seasoning is complete, which is indicated by a sudden change in the color of the escaping vapors, the process of charring begins at the top and proceeds downwards precisely like the seasoning process. The watery vapors driven off during seasoning are not preserved but are allowed to escape through vents temporarily left open around the base of the kilns and through the top of the kiln-chimneys, which, during this stage, are disconnected from the suction main and left open at the top. The time required for the several stages in the cycle of operations in producing a kiln of charcoal is as follows: As one 60-ton blast furnace requires five thousand bushels of charcoal daily, or the output of two kilns, the total number of kilns in a plant to furnish a continual supply of fuel must be equal to twice the number of days in a cycle plus a margin for relays, for repairs, and unusual delays; the margin is usually chosen at one-sixth the effective number of kilns, so that the total number of kilns comprising a plant ·2 (18) + 42, of which at any one time, = 4 kilns are being charged and closed. (36) : = These forty-two kilns are arranged in two distinct batteries of twentyone kilns each. Each battery has its own condensers and suction main carrying the products of distillation to the condensers, and its own gas main leading the non-condensable gases back to the kiln furnaces. The condensers are composed of tall wooden tanks five feet square by twenty feet high, through which the products of distillation pass, each enclosing ninety-nine vertical copper pipes two inches in diameter through which the condensing water flows. The condensed products are trapped out at the bottom of each condenser, of which ten comprise a battery, and conveyed to cooling tanks where the tar is separated from the pyroligneous acid liquor by cooling. The tar is not at present distilled further, but is used to coat the kilns to render them impervious to air, and for this purpose one coating of tar suffices for four burnings while the usual coating of lime whitewash has to be repeated after each burning. The circulation of the gaseous products through the system is maintained by exhaust fans which draw the non-condensed gases through the condensers and force them through the gas main back to the kilns when they are injected into the furnaces by a steam jet from a 4-inch orifice playing in the center of a one inch nozzle on the gas pipe. The minimum amount of air necessary to effect the perfect combustion of the gases is admitted through regulating dampers in the front of the furnace. From the liquor coolers the pyroligeneous acid liquor is conveyed to the distilling house, where the acetic acid in the liquor is converted into acetate of lime; the liquor is then sent to the fractional distillation system which comprises eight primary stills and condensers, four intermediate stills and condensers and two final or shipping stills and condensers. The stills are circular tanks each holding about 2,500 gallons and are heated by steam coils of two-inch copper pipe. The several stills of each of the three series are operated abreast. The distillation is not carried on continuously, but each series is charged and the distillation carried on until all of the alcohol available is evaporated when the stills are emptied and recharged with new liquor. The degree of concentration attained in each series of stills is as follows: The liquor entering the primary stills contains 14% alcohol. "distillate from 66 66 66 66 15% In the final form the crude alcohol is sent to the refineries. The resulting product, methylic alcohol or hydrate of methyl (CHO) is of wide application in the arts, being extensively used as a solvent for gums and varnishes for which purposes varnish manufacturers report it from four to five times as rapid in action as grain alcohol. Methylic alcohol has never been produced by fermentation but, judging from its mode of production in the charcoal kilns, its artificial production by synthesis may be inferred as possible. As none of the charcoal is sacrificed for carrying on the carbonization of the wood and as the action of the kilns during carbonization and cooling is under the control of the operator, it is reasonable to expect a larger yield of charcoal per cord of wood than in the common methods of burning in ground pits or common bee-hive ovens. The resulting charcoal is also better adapted to bear the burden in the blast furnace than the common charcoal, being both firmer and denser as is shown by the fact that while the average weight of common charcoal per bushel in Tennessee does not exceed sixteen pounds that made from the same varieties of wood by this process weighs twenty pounds per bushel. The following exhibit shows the comparative amounts produced by the common and the improved methods respectively :The average yield of charcoal per cord of wood in U. S. weight per bushel of 2,688 cu.in. = 38.1 bu.1 in U. S. = = 19.0 lbs.1 18% resulting ratio by weight of charcoal to wood in U. S. = 190/2 10 16%3 "in Pyrenees = 17%* The resulting general average in above countries The average ratio by weight, charcoal to wood, by Pierce process 2 Sauvage. Ann. des Mines, 1837. Francois. Traitment direct des minerais de Fer. Result of seven years practice at different plants. |