A PRELIMINARY REPORT ON CLAYS OF VLORIDA 209


is now removed in order to obtain the underlying marl for road purposes, this clay might be of some value as a by-product.
 This mixture has excellent drying and working qualities, is redburning, and would be suitable for a good grade of structural materials. The shells associated with these two clays are detrimental and would necessarily have to be removed or very finely ground. The physical properties are:


 Physical Properties of DeLand City Clay (Lab. No. 0-48).
 Plasticity, judged by feel........... .Excellent.
 W ater of plasticity................. 29.90%
 Pore water ....................... 6.12%
 Shrinkage water .................. 23.78%
 Linear air shrinkage............... 13.0 %
 Volume air shrinkage.............. 38.0 %
 Modulus of rupture, average........ 966.5 pounds per square inch.
 Slaking test ....................... 30 minutes.
 Steel hard at cone 010.
 Fire tests:
Temperature. Linear Shr. Absorption. Porosity. Color.
 Per Cent. Per Cent. Per Cent.
 950*C. 1.0 11.40 27.95 Brick red.
 1050 2.0 9.72 25.95 Brick red.
 1150 2.0 9.96 25.20 Brick red.
 1190 1.0 7.49 21.20 Brick red.
 1230 0.5 12.51 26.75 Brick red.

 A sandy clay, occurring in the northwest part of the city of DeLand, was formerly worked for common brick. The deposit consists of three feet of sand, three feet of red-mottled clay, and three feet of a buff clay, underlain by a sand.
 This clay may be used for a porous, common brick. The physical properties are:


 Physical Properties of Herman Brown Brick Yard Clay (Lab. No. 0-35).
 Plasticity, judged by feel........... Excellent.
 Water of plasticity................. 26.70%
 Pore water ....................... 0.00%
 Shrinkage water .................. 26.70%
 Linear air shrinkage............... 10.7 %
 Volume air shrinkage.............. 27.75%
 Modulus of rupture, average........ 306.4 pounds per square inch.
 Slaking test ....................... 10 minutes.