It is rather porous burning, in spite of its high fire shrinkage

at cone IO.

Several samples were also tested from C. S. Edgar's bank (Freeman bank) (Loc. 94). The section (exposed in Sept., 1901) is given below, in order to better identify the samples:

A sample from layer 7 (Lab. No. 405) was a homogeneous gritty clay of porous texture and smooth fracture. It slaked fairly fast and all passed through a 100-mesh sieve. When mixed with 32 per cent. water it gave a mass of moderate plasticity, whose tensile strength was 52 pounds per square inch and air shrinkage 7 per cent. It behaved as follows when fired:

Burning tests of a No. 1 blue fire clay, C. S. Edgar, Sand Hills.

As is shown by the absorption tests this is a rather open-burning clay, and does not become at all dense until cone 15. It burns steel-hard at cone 5, and at cone 27 is vitrified. This is a sagger clay.

A second sample tested from this pit was a mixture of layers 2 and 4 of the section given above. This mixture (Lab. No. 406) worked up with 25 per cent. of water, and had an average tensile strength of 98 pounds per square inch with an air shrinkage of 6.5 per cent. Its burning qualities were as follows:

29 CL G

Burning tests of a mixture from C. S. Edgar's bank, Sand Hills.

This shows a mixture of much denser-burning quality than the preceding one from the same bank, there being a difference of 13 per cent. in the absorption at cone 5, and 4 per cent. at cone 15. It is not quite as light burning, due to the presence of a greater percentage of iron oxide in the clay. It is not highly refractory, for at cone 30 it was viscous.

A number of fusibility tests were made on other samples from the region around Sand Hills and Bonhamtown with the following results:

The fusibility of these three specimens lay on the border line between refractory and semirefractory clays, and it was thought best to include them in the refractory class.

This specimen, from a pit 300 feet east of the stable, vitrified at cone 29. The cone of fusion was not determined, but the clay probably belongs in the refractory group.

Burt Creek.-On the south side of the Raritan river, the South Amboy fire clay is opened up at several points as mentioned in Chapter VIII. The most extensive of the fire-clay pits are those of J. R. Such (Pl. L, Fig. 1) and J. R. Crossman. At the former locality (Loc. 67) a sample of No. 1 blue fire clay was collected. This is the material which in its washed form is sold as ball clay.