. Appleton's dictionary of machines, mechanics, engine-work, and engineering. t when it arrives directly before the tujeres, the combustion of thefuel shall not give rise to any gaseous oxidating product; such, for example, as carbonic acid. The flux(the selection of which, as well as that of the fuel, depends on the quality of the ore) must be used insuch a state as not to produce any oxidating matter during the formation of the slag. For this reason,when the nature of the ore requires the employment of lime as a flux, the lime should be used in acaustic state, and not as a carbonate; and for
. Appleton's dictionary of machines, mechanics, engine-work, and engineering. t when it arrives directly before the tujeres, the combustion of thefuel shall not give rise to any gaseous oxidating product; such, for example, as carbonic acid. The flux(the selection of which, as well as that of the fuel, depends on the quality of the ore) must be used insuch a state as not to produce any oxidating matter during the formation of the slag. For this reason,when the nature of the ore requires the employment of lime as a flux, the lime should be used in acaustic state, and not as a carbonate; and for the same reason it is advisable to use a blast of dry air,that is to say, air deprived of aqueous vapor. The products of the furnace are, In the first place, thegases arising from the combustion of the fuel; secondly, the vapors of zinc; thirdly, the non-volatilizablematters, consisting of scoriae or slag, and of reduced metallic substances of greater density than thezinc. The throat of the furnace being closed, the gases arising from the combustion of the fuel pass off through the passages A1, and are made use of either for the purpose of heating the boiler of tl)8steam-engine which drives the blowing machine, or to burn lime when used for a flux, or to melt thezinc which is carried over in a state of vapor, or to dry and roast the ores. The vapors of zinc arecondensed in the passages F F, and may be easily withdrawn therefrom by means of a rake, (the rec-tangular form of the passages FF affording great facilities for this purpose,) after which they are re-duced and formed into ingots or bars. The non-volatilized or residual matters, which collect on thesole or hearth of the furnace, are run off from time to time according as they accumulate. The ores containing zinc may be divided into two classes: firstly, those in a state of oxide, eitherfree or combined with carbonic or silicic acid ; secondly, those containing sulphurot of zinc, (blende.)When the ores are of the f
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