482 



FOUNDING; FOUNDRY 



third must resist sudden alternations of temperature ; and a fourth must bo pretty 

 hard. 



The filling-in of the melted metal is managed in two -ways. For strong pieces, whose 

 moulds can be buried in the ground at 7 or 8 yards' distance from tho furnace, tho 

 metal may be run in gutters, formed in tho sand of the floor, sustained by plates or 

 stones. The clay plug is pierced with an iron rod, when all is ready. 



When from the smaller size, or greater distance of tho moulds, the melted metal 

 cannot bo run along the floor from the furnace, it is received in cast-iron pots or ladles, 

 lined with a coat of loam. Those are either carried by tho hands of two or more men, 

 or transported by tho crane. Between tho successive castings, the discharge hole of 

 the furnace is closed with a lump of clay, applied by means of a stick, having a small 



disc of iron fixed at its end. 



I 



1003 



After the metal is some- 

 what cooled, the moulds aro 

 taken asunder, and the ex- 

 crescences upon tho edges of 

 the castings are broken oif 

 with a hammer. They aro 

 afterwards more carefully 

 trimmed or chipped by a 

 chisel when quite cold. The 

 loss of weight in founding is 

 about 6 per cent, upon tho 

 pig iron employed. Each 

 casting always requires tho 

 melting of considerably more 

 than its own weight of iron. 

 This excess forms tho gates, 

 false seams, &c. ; tho whole 

 of which being deducted, 

 shows that 1 cwt. of coke is 

 consumed for every 3 cwts. 

 of iron put into the furnace ; 

 for every 138 cwts. of crude 

 metal, there will be 100 cwts. 

 of castings, 32 of refuse 

 pieces, and 6 of waste. 



^^.1002, Cupola furnace, 

 requires a little further de- 

 scription. It is 3 feet wide 

 within, and 13 feet high. 

 m m, solid body of masonry, 

 as a basis to tho furnace. 



b b, octagonal platform of 

 cast iron, with a lodge in 

 which tho plates a a a a aro 

 engaged. 



a a, eight, plates of cast 

 iron, 1 inch tliirk, absolutely 

 similar ; only one of them is 

 notched at its lower part in 

 c, to allow the melted nu-tal 

 to run out, and two of tho 

 others have six apertures, 

 g g ff, &c. to admit tho tu- 

 yeres. 



c, orifice for letting tho 

 metal flow out. A kind of 

 cast-iron gutter, c, lined with 

 loam, is fitted to tho orifu- 1 . 



d, hoops of hammered iron, 

 4 inches broad; i inch thick for tho bottom ones; and $ inch for tho upper oats. 

 The intermediate hoops decrease in thickness from below upwards between theso 

 limits. 



c, cast-iron gutter or spout, lined with loam, for running off tho mctai. 

 / /, cylindrical piece of cast iron, for increasing tho height and draught of the 

 -furnace. 



