Despite the great increase of con crete and steel construction, brick seems to be used as much as ever, as they are not affected by the weather, fire or city atmosphere. which affects the softer building stones seriously. They are cheaper than stone and can be used with cut stone or terra-cotta trimmings. Hard burned bricks are used for piers, though not so good for this purpose as stone work, and in very dry soils are sometimes used for founda tion walls. If there is any dampness of the soil, the outside of brick foundation walls is sometimes painted with water-proof paint.
B 'ricks are made from sand and clay, the clay in different localities making bricks of different characteristics. A sandy clay is most desirable. For the better kinds of brick, clay is often chosen from different places and combined with the greatest care. (See BRICK-MAKING MA CHINERY). Terra-cotta and pottery are burned in kilns which are arranged to let in heat half way up the kiln so that it will be drawn down on to the pile of terra-cotta and through the floor of the kiln into the chimney. This is said to give a more even heat. If there is iron in the clay the color of the brick will be red; the ordinary white bricks are generally due to lime. The proportion of iron makes the red of vari ous shades, according to the amount. Lime and iron make a cream-colored brick. Brown bricks are due to the presence of magnesia; and magnesia andiron make a yellow brick. Dif ferent clays give varying color effects, and the mixture of clays with mortar colors, or paint ing the exposed surfaces, gives desired effects.
Bricks should not absorb more than from one twentieth to one-tenth of their weight of water. This is a test that can be easily applied. Soft bricks may absorb as much as a quarter of their weight. Bricks should ring when struck, as cracked or soft bricks will give a dull sound. They should not have any cracks or large lumps or foreign substance, such as lime or coarse gravel. They should run all the same dimensions with true surfaces, though for rustic work rough bricks are often desired. The approximate size of a brick is 2 inches X 4 inches X 8 inches. In the Eastern States 734 inches X 334 inches X 2/ inches; but in the Western States the dimensions are slightly larger. In every case where brick work has to be figured for cutting stone trimmings, the brick should be laid up and measured. Pressed brick are generally 834 inches X 454 inches X 234 inches in size. Roman brick is 12 inches long and PA inches thick. Norman brick is 12 inches long and 2 inches thick. Bricks weigh four or five pounds apiece.
The Strength of Materials and Structures' (1887) ; Baker, Treatise on Masonry Construction> (1909) ; Merrill, (Stones for Building and Decoration> (1891) ; Patton, Practical Treatise on Foun dations' (1909) ; Mitchell, C. F., (Brickwork and Masonry' ; (Building Code of New York.> See QUARRYING; STONE-CUTTING AND DRESSING.