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A sample of the crude clay (Lab. No. 391) showed it to be a very plastic feeling clay of fine grain and fast-slaking qualities. It required 39 per cent. of water to temper it to a mass of the proper consistency for molding. The air shrinkage of the bricklets was 5 to 6 per cent., but when air dried they did not feel very hard or dense, and on the contrary were rather soft and pulverulent. The tensile strength of the air-dried bricks was 59 pounds per square inch.

Burning tests of a No. 1 blue fire clay. J. R. Such, Burt Creek.

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Inasmuch as the washed ball clay, which is purer than the crude, was well vitrified at cone 27 (see below), it seems proper to classify this clay as refractory, although its fusibility was not tested in the Deville furnace.

I blue.

Several grades of clay are mined in the pits of J. R. Crossman (Loc. 65 and 66), near Burt Creek. A good grade of fire clay from locality 66, was viscous at cone 33. This is known as No. At times it is found sufficiently free from impurities to wash for a ball clay, although this is not commonly done. Some of the buff fire clays from this pit are used by wall-plaster manufacturers, while other grades are sold for saggers, and enameledbrick manufacture.

A red-mottled clay1 from another of Crossman's pits (Loc. 65, Lab. No. 386) was also tested. It was a clay of rather low plasticity but rapid-slaking qualities, working up to a plastic mass with 30 per cent. of water. Its air shrinkage was low, being 4 per cent., and its tensile strength of 15 pounds per square inch was equally low. A lump of the crude clay burned to cone 10 was

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quite porous and showed the presence of many small fused specks. The behavior of the molded material under fire was as follows:

Burning tests of a red-mottled clay. J. R. Crossman, Burt Creek.

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These speckles showed on the fracture even at cone 3, and the clay became steel-hard slightly above this cone. In spite of its red color, which suggests a high per cent. of ferric oxide, it is more refractory than a No. 1 blue fire clay dug in the same pit (p. 457), for it does not become viscous until cone 31.

Ball Clays.

Refractory ball clays occur in the South Amboy fire-clay bed, and those dug by C. S. Edgar and J. R. Such were tested with the following results.

Sayreville.-Washed ball clay from pits of C. S. Edgar, east of Sayreville (Pl. XLIX, Loc. 268, Lab. No. 723). This is a whitish, very fine-grained, soft clay. Its fineness can be judged from the fact that it contains 87 per cent. of clay particles which are under 120 inch in diameter. It slaked fast and worked up with 39.1 per cent. of water to a plastic-feeling mass whose air shrinkage was 5 per cent., but the clay had a very low tensile strength. Its burning qualities were as follows:

Burning tests of washed ball clay. C. S. Edgar, Sayreville.

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It burned steel-hard at cone 5, but showed many fine cracks. The material is not used alone, but mixed with other white-burning clays. It is refractory, being only vitrified at cone 27.

Burt Creek.-Another sample of washed ball clay was examined from J. R. Such's pit (Loc. 67, Lab. No. 389). This is like

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Clay-washing plant of Edgar Bros., near Sayreville, N. J. The settling tanks and troughing are seen in the center and left of the picture, while behind them are the drying sheds.

wise a soft, fine-grained clay, which slaked slowly. It worked up with 40 per cent. of water, and had an air shrinkage of 5 per cent., but its tensile strength was low and all the briquettes developed cracks in drying. It behaved as follows when burned:

Burning tests of washed ball clay. J. R. Such, Burt Creek.

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This term is used chiefly in the area around Woodbridge and South Amboy, and refers to beds of fire clay, of No. 2 grade, good plasticity, and dense-burning qualities. On account of the two last mentioned qualities they are specially adapted for the manufacture of stoneware. They can therefore be called a variety of No. 2 fire clay. In some pits two grades of stoneware clay are recognized. Those dug in the Woodbridge area are found in the Woodbridge fire-clay bed, and those on the south side of the Raritan river occur in the Amboy stoneware-clay bed.

Woodbridge. In the Woodbridge district a sample of stoneware clay from the eastern pit of W. H. Cutter (Loc. 29) was tested.

For purposes of identification the section carrying the stoneware clay is given below:

1. Drift.

Section of W. H. Cutter's clay bank, Woodbridge.

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