Earthenware of this description is weak, porous, liable to the attacks of frost, and is not adapted to resist the atmosphere or other destroying agents.
2. Fireclay Ware, made from the fireclays of the coal-measures (see p. 120).
It is much used for common varieties of the different articles about to be described, especially in the localities where the fireclay is found; but it is inferior to stoneware or to terra cotta for nearly every purpose.
3. Stoneware is made, as before stated, from clays of the Lias formation, mixed with sand and ground pottery, to prevent shrinkage.
The characteristics of this material have already been pointed out (see p. 128).
Its strength, durability, imperviousness, and resistance to destructive influences make it an admirable material for sanitary ware, sewer pipes, ornamental works exposed to the atmosphere, and for vessels to contain chemical compounds.
4. Terra Cotta is often used for pipes and other miscellaneous articles.
Its composition, and the mode in which it is manufactured, have already been described.
It is inferior to stoneware, inasmuch as it is more absorbent and less dense in grain. It is burnt at the same heat as fireclay goods, but is superior to them in strength and durability.