A PRELIMINARY REPORT ON CLAYS OF FLORIDA 153


 This clay is underlain by sand and sandy clay. The overburden ranges from one to six feet. This clay is free from sand, but contains small
 amounts of very fine mica flakes. Its physical properties are:


 Physical Properties of Muscogee Cut Clay (Lab. No. o-4).
 Plasticity, judged by feel............ Excellent.
 W ater of plasticity................. 27.90%
 Pore w ater ....................... 0.68%
 Shrinkage water ................... 27.22%
 Linear air shrinkage................. 6.4%
 Volume air shrinkage............... 18.2%
 Modulus of rupture, average........ 214.3 pounds per square inch.
 Slaking test ....................... 1 hour.
 Steel hard at cone 1.
 Overfires at cone 15.

 Fire tests:
Temperature. Linear Shr. Absorption. Porosity. Color.
 Per Cent. Per Cent. Per Cent.
 950"C. 0.9 19.75 36.43 Pink.
 1050 0.1 18.32 35.81 Pink.
 1150 5.1 9.25 16.58 Buff.
 1190 5.1 9.42 14.23 Buff.
 1230 5.6 6.50 12.39 Cream.
 1310 5.6 5.30 11.04 Cream.
 1370 6.1 0.49 2.17 Gray.
 1430 4.6 1.05 5.41 Gray.

 On the property of I. L. Schaffer on the Pensacola and Alabama Railroad, about eleven miles northwest of Pensacola, is another exposure of a similar clay. This is gray and brown mottled, occurring in a very irregular deposit overlain unconformably by a cross-bedded sand. The clay underlies an extensive area in this locality, but is quite variable in thickness. In places it is as much as fifteen feet thick. It has the following physical properties:


 Physical Properties of Schaffer Clay (Lab. No. o-4o).
 Plasticity, judged by feel............ Excellent.
 W ater of plasticity................. 26.15%
 Pore water ........................ 0.18%
 Shrinkage water ................... 25.97%
 Linear air shrinkage................ 8.3%
 Volume air shrinkage ............... 23.95%
 Modulus of rupture, average........ 262.8 pounds per square inch.
 Slaking test ....................... 30 minutes.
 Steel hard at cone 05.