METALLURGICAL COLLECTIONS. 
99 
heated to redness it sublimes, and if a proper vessel be placed 
to receive the sublimed substance, a cake of fine red colour is 
obtained, called cinnabar ; this being reduced to powder forms 
the vermilion of commerce. 
Iron and Steel Manufacture. 
Table Gases 9 and 11. — In well-marked divisions in Case 9 
the results of the processes of smelting the ores of iron are 
shown from the following iron works : — 
Whitehaven Iron Works 
Low Moor ditto 
Bowling ditto 
Farnley ditto 
Russell's Hall ditto - 
Plymouth ditto 
Dowlais ditto 
Maesteg ditto 
Monkland ditto 
Cumberland. 
Yorkshire. 
South Staffordshire. 
Glamorganshire. 
- Lanarkshire. 
The iron ore, or “mine,” if in the state of carbonate, is first 
calcined, either in open heaps, or more usually in kilns. By 
calcination, carbonic acid gas, water and other volatile ingre- 
dients are expelled. The smelting of the ore, whether raw or 
calcined, is effected in the blast furnace. The furnace which is 
now often made of very large size, is charged with ore, fuel, and 
flux. The flux is usually limestone, which yields lime to combine 
with the silica of the ore, thus forming a fusible double silicate 
of lime and alumina, which appears as a slag ; while the iron is 
separated and collected in a fluid state at the bottom of the 
furnace, from which it flows out at the proper time and is 
collected in sand moulds prepared for it, producing the masses 
known by the name of pigs. 
As an intense heat is required for smelting iron ores, a strong 
blast of air is constantly injected through twyers. By employ- 
ing heated air a saving is effected in the process of smelting, and 
it is now common to make the air traverse pipes which are 
heated in a stove before it enters the blast furnace. Iron pre- 
pared by the hot-air process is called hot blast iron , but when 
the air is admitted to the blast furnace cold it is known as cold 
blast. 
The crude metal obtained from the blast furnace is termed 
cast-iron , of which there are three leading varieties, known as 
grey, mottled and white cast-iron. 
All these varieties contain a considerable amount of carbon, 
sometimes as much as five per cent., together with small quan- 
tities of silica, sulphur, phosphorus, &c. These impurities are 
oxidized during the conversion of the cast-iron into wrought or 
malleable iron. This is usually effected in a reverberatory 
furnace, where the metal is exposed to a current of air and 
