A PRELIMINARY REPORT ON CLAYS Or FLORIDA 151


appreciable thickness and ranges from six to fifteen feet. It has the following physical properties:

 Physical Properties of Dexland Clay No. 4 (Lab. No. o-12).
 Plasticity, judged by feel............ Excellent.
 W ater of plasticity ................ 25.20%
 Pore w ater ........................ 1.37%
 Shrinkage water ................... 29.95%
 Linear air shrinkage ............... 8.5 %
 Volume air shrinkage............... 19.4%
 Modulus of rupture, average ........ 207.9 pounds per square inch.
 Slaking test ....................... 20 minutes.
 Steel hard at cone 1.
 Fire tests:
Temperature. Linear Shr. Absorption. Porosity. Color.
 Per Cent. Per Cent. Per Cent.
 950'C. 1.0 18.70 35.25 Cream.
 1050 1.0 17.95 34.60 Cream.
 1150 1.5 17.50 34.20 Cream.
 1190 1.5 13.80 28.65 Cream.
 1230 1.5 11.58 27.75 Cream.
 1310 1.5 10.58 25.20 Cream.
 1370 1.5 7.57 25.90 Brown.
 1430 2.5 6.30 20.40 Brown.

 Dexland No. 5 is a gray plastic clay ranging from six to ten feet
in thickness and exposed about three feet above the river level at the tipper bluff. Its physical properties are:

 Physical Properties of Dexland Clay No. 5 (Lab. No. 0-73).
 Plasticity, judged by feel........... Excellent.
 W ater of plasticity................. 28.60%
 Pore water ........................ 0.85%
 Shrinkage water ................... 27.85%
 Linear air shrinkage................ 10.4 %
 Volume air shrinkage............... 32.8 %
 Modulus of rupture, average........ 384.4 pounds per square inch.
 Slaking test ....................... 10 minutes.
 Steel hard at cone 010.
 Fire tests:
Temperature. Linear Shr. Absorption. Porosity. Color.
 Per Cent. Per Cent. Per Cent.
 950'C. 0.1 24.30 32.05 Cream.
 1050 1.1 17.20 30.65 Cream.
 1150 2.6 9.86 21.50 Brown.
 1190 5.6 6.24 9.70 Brown.
 1230 5.6 6.16 9.72 Gray.
 1310 6.6 4.08 6.65 Gray.

 Dexland No. 6 is an eiglht-inch layer of black plastic clay exposed about four feet above the river at the lower end of the Upper Bluff. Its