Gault Bricks are from the clay between the upper and lower greensand. They are white, and generally very dense and heavy, being to some extent lightened by a large frog, or by holes through their thickness.
Staffordshire Blue Bricks are made from the local clays, which contain some 10 per cent of oxide of iron, converted under great heat into the black oxide. They are of a dark blue colour or nearly black. They have an enormous resistance and compression, are very hard, non-porous, very durable, and much used for paving, copings, etc.
Fareham Bed Bricks are made near Portsmouth, and are much used for superior face-work.
Enamelled Bricks have a white china-like surface, and are used for lavatories, dairies, etc.
Dutch Clinkers are very small, well-burnt hard bricks, used for facing.
Fire Bricks are made from "fire clays," found generally in the coal-measures. They are capable of withstanding very high temperatures, and are much used for lining furnaces, etc.
Terra Cotta is made from mixtures of peculiar clays with ground glass, pottery, and sometimes sand. It is apt to warp in manufacture, but is much used for building, is very bard, strong, and durable in any atmosphere.
These are innumerable in form, but it is important to distinguish between the material of which they are made.
Unglazed ware is made from ordinary clays, weak, and unable to resist frost.
Fire-clay Ware, made from fire clays and glazed, used for common work.
Stoneware, made from Lias clays, glazed, is very strong, durable, and used for the best work.
Terra Cotta, made from the material above described. It is inferior to stoneware, being more absorbent, but better than fire-clay goods.