IRON. 
525 
five times their own weight. It appears that the 
other mountain contains loadstones on its summit, 
but attended with a singularity that makes them 
useless ; for as soon as they are detached their poles 
become multiplied and confounded together. 
All iron ore, after it is dug from the mine, must 
be smelted before it is fit for use. To effect this, 
furnaces of very considerable magnitude are con- 
structed, of the shape of an egg, with the largest 
end toward the ground. The inner wall is built of 
fine stone, which powerfully resists the heat, and 
this is surrounded with more building till the co- 
nical shape is lost, and the whole forms a square 
gradually converging towards the top. These build- 
ings are from l6‘ to 25 feet high, and from 10 to 
14 in width, in the inside. Near the bottom of the 
furnace there is an aperture for the insertion of a 
large pair of bellows worked by a steam-engine, 
and two or more holes are left ready to be occa- 
sionally opened at the bottom to permit the melted 
metal to flow out, and to remove the scoria. When 
the inside of the furnace has been strongly heated 
by throwing in charcoal and coke with lighted 
brush-wood, the process of smelting begins, and 
fuel, ore, and flux, in alternate layers, are con- 
tinually put in day and night. The flux which 
is used to assist in melting the metal is generally 
limestone, and the workmen never let the fire go 
out till the furnace wants repair, which is fre- 
quently a period of some years. The ore thrown 
in, in the manner just described, gradually subsides 
