. The pictorial sketch-book of Pennsylvania, or, Its scenery, internal improvements, resources, and agriculture, populary described . at prudence, watchfulness, and activity. Tosupply the furnace with fuel, a barrow, similar to the above, is em-ployed. A new furnace requires firing for two or three weeks beforethe rermlar charges of ore can be thrown in. After the stack andhearth-stone are sufficiently dry, the charges of ore are introduced insmall quantities, and are afterwards gradually increased. The furnace is always exposed, at the outlet, to the liability of chil-ling ; that is, the iron
. The pictorial sketch-book of Pennsylvania, or, Its scenery, internal improvements, resources, and agriculture, populary described . at prudence, watchfulness, and activity. Tosupply the furnace with fuel, a barrow, similar to the above, is em-ployed. A new furnace requires firing for two or three weeks beforethe rermlar charges of ore can be thrown in. After the stack andhearth-stone are sufficiently dry, the charges of ore are introduced insmall quantities, and are afterwards gradually increased. The furnace is always exposed, at the outlet, to the liability of chil-ling ; that is, the iron clinkers in the interior, and suddenly coolsnear the mouth or top-hole, impairing the di-aft, and not unfrequentlyentirely choking it up. in whicli case the whole interior work has 120 LOCOMOTIVE SKETCHES. sometimes to be taken out and rebuilt. Under these circumstances,introduction of the charges of ore and fuel becomes an importantmatter. A measure often used, similar to the above, is constructedof two half-inch round iron-bars, so connected at one end that onebar sinks into the furnace, while the other serves as a handle; b. CHARGE MEASURE OP FURNACES. forming the handle ; c the measure, and the iron plate, a, prevents thesinking of the rod into the materials. There are various other devi-ces to effect the same object, but these are the most common andsimple. The philosophical principles of the blast furnace, or the causeswhich separate the several substances with which it is charged andprecipitate the metals of the ore, are by no means easily the effects produced are generally well understood, the natureof those chemical and mechanical changes and combinations, formedby the decomposition of the combustible material in the blast, duringthe various stages of ignition through which it passes, is not easily ex-plained. The engraving on page 121 exhibits Mr. Overmans theor}^ of theblast,according towhich it appears that, at a, (the pointswhere the blastis receiv
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Keywords: ., bookcentury1800, bookdecade, booksubjectminesandmineralresources
