A PRELIMINARY REPORT ON CLAYS OF FLORIDA 
151 
appreciable thickness and ranges from six to fifteen feet. It has the fol¬ 
lowing physical properties: 
Physical Properties of Dexland Clay No. 4 . (Lab. No. 0 - 12 ). 
Plasticity, judged by feel. Excellent. 
Water of plasticity . 25.20% 
Pore water. 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. 
Per Cent. 
Absorption.. 
Per Cent. 
Porosity. 
Per Cent. 
Color. 
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 
upper bluff. Its physical properties are: 
Physical Properties of Dexland Clay No. 5 (Lab. No. 0 - 73 ). 
Plasticity, judged by feel... 
Water of plasticity. 
Pore water. 
Shrinkage water. 
Linear air shrinkage. 
Volume air shrinkage. 
Modulus of rupture, average 
Slaking test. 
Steel hard at cone 010. 
Excellent. 
28.60% 
0.85% 
27.85% 
10.4 % 
32.8 % 
384.4 pounds per square inch. 
10 minutes. 
Fire tests: 
Temperature. 
Linear Shr. 
Per Cent. 
Absorption. 
Per Cent. 
Porosity. 
Per Cent. 
Color. 
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 eight-inch layer of black plastic clay exposed 
about four feet above the river at the lower end of the Upper Bluff. Its 
