Terra-cotta Works, and in 1879 changed to the Perth Amboy Terra-cotta Company. (Plate XXXI.) This was followed in 1888 by the establishment of the New Jersey Terra-cotta Works. The present Standard Terra-cotta Works was organized in 1890 under the name of the Architectural Terra-cotta Works, and the others are of still more recent date. One plant at Matawan has been converted into a floor-tile works. The value of the terra cotta produced in New Jersey in 1902 was $861,730.1 List of producers of terra cotta in New Jersey. Perth Amboy Terra-cotta Company, Perth Amboy. 1 Burlington Terra-cotta Company, Beverly and Moorestown. South Amboy Terra-cotta Company, South Amboy. Mineral Resources, U. S. Geol. Survey, 1902. Chap. on Clay-working Industries. HOLLOW WARE FOR STRUCTURAL WORK. Character. Under this heading are included fireproofing, terra-cotta lumber, hollow blocks and hollow bricks. These are all hollow, being molded through a stiff-mud die (see Pl. XXXII, Fig. 1), and may contain one or more cross webs or partitions to give them strength. Fireproofing is the term applied to those forms used in the construction of floor arches, partitions and wall furring for columns, girders and other purposes in fireproof buildings. Terra-cotta lumber is a form of fireproofing that is soft and porous, owing to the addition of a large percentage of sawdust to the clay. The former burns off in the kiln, thus leaving the material so soft and porous that nails can be driven into it. It is used chiefly for partitions. Hollow blocks are used for exterior walls, in both fireproof and nonfireproof buildings. They are of rectangular outline. Hollow brick are like hollow blocks in form, but no larger than ordinary building bricks. A number of different shapes and sizes of fireproofing are made, and while the majority of them agree in being 12 inches long, the other two dimensions may vary. Thus, of the blocks which are 12 inches long, the other, dimensions may be 6 by 3 in., 6 by 4 in., 6 by 5 in., 6 by 6 in., 6 by 7 in., etc., or perhaps 3 by 8 or 3 by 12 in., etc. A large number of the fireproof shapes made are for floor arches, and in such cases the architect commonly specifies the depth of the arch while the width of the blocks is governed by the width of the span. The weight of the arch will depend on its depth. The cost of fireproofing is commonly figured by the ton. Hollow blocks are usually made in 8-inch lengths, but vary in their other two dimensions, being 4 by 16, 6 by 16, 8 by 16, 10 by 16, 12 by 16, etc. They are used quite extensively in the central States, but not so much in the eastern ones. Hollow blocks are made with either smooth, corrugated or ornamented surfaces. Sizes 8 by 4 by 16 in. are sold for about $0.07 each, and 8 by 8 by 16 in. at $0.10 each. Hollow bricks are often used for the interior course of exterior walls, and the plaster can be laid directly on them without the use of lathing. Raw materials.-The clays used for making fireproofing and hollow bricks are often a grade of fire clay, but those manufactured in New Jersey are made from a mixture of an impure redburning clay, to which a certain proportion of fire clay is sometimes added. The former is obtained in great abundance from the laminated clay in the upper part of the Woodbridge clay bed, as well as from Clay Marl II. While the different classes of |