A PRELIMINARY REPORT ON CLAYS OF FLORIDA 
203 
protective treatment without serious losses. The percentage of loss here 
is incredibly low. 
The clay deposit, which is probably the Citronelle formation, is sedi¬ 
mentary and consists of two strata. The upper one has a slight amount 
of sand, is brownish in color, and is about two feet in thickness. The 
lower one is gray in color, free from sand but has a slight amount of 
mica. Its thickness is unknown. The deposit is overlain by about two 
feet of sand and soil, which is removed. The proportion of the two clays 
used in the Allentown brick is one part of the upper brown one to two 
parts of the lower gray clay. 
This deposit of clay has an extensive distribution in this vicinity 
and probably is connected with the deposits of similar clay farther 
westward in Escambia County. 
Either of these clays may be used for stoneware, terra-cotta, or 
roofing tile. The small amount of sand in the upper clay should be 
washed out before it is used for the better grades of ware. The upper 
clay has the following physical properties: 
Physical Properties of Allentown Top Clay (Lab. No. 0 - 14 .). 
Plasticity, judged by feel. Excellent. 
Water of plasticity. .. 29.90% 
Linear air shrinkage. 8.6 % 
Volume fire shrinkage... 24.2 % 
Modulus of rupture, average........ 324.2 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. 
0.9 
20.20 
38.90 
Pink. 
1050 
1.6 
17.10 
33.25 
Pink. 
1150 
6.9 
8.55 
19.80 
Gray. 
1190 
6.9 
7.08 
17.25 
Gray. 
1230 
6.9 
6.85 
15.60 
Gray. 
1310 
8.9 
3.14 
8.85 
Gray. 
1370 
9.9 
1.55 
8.45 
Gray. 
1430 
9.9 
1.12 
4.72 
Gray. 
