A PRELIMINARY REPORT ON CLAYS OP FLORIDA 173 
The plant is small and has only one kiln which has a 110,000 capaci¬ 
ty. All the work is done by boys ranging in age from' eight to eighteen 
years. 
The clay has excellent plasticity. Its linear fire shrinkage increases 
from 3.1 per cent at cone 010 to 10.6 per cent at cone 5. Its porosity and 
absorption percentages are low at cone 1 and remain so until after cone 
9 is passed. This clay should be used only for common structural materi¬ 
als as common and face brick, fireproofing, hollow-block ware, drain tile 
and similar products and should be burned at about cone 010. Its physi¬ 
cal properties are: 
Physical Properties of Florida Industrial School Clay (Lab. No. 0 - 28 ). 
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. 
Overfires at cone 12. 
Excellent, 
36.65% 
0.46% 
36.19% 
14.40% 
38.10% 
421.2 pounds per square inch. 
5 minutes. 
Fire tests: 
T emperature. 
Linear Shr. 
Per Cent. 
A bsorption. 
Per Cent. 
Porosity. 
Per Cent. 
Color . 
9S0°C. 
3.1 
11.95 
26.00 
Brick red. 
1050 
10.6 
8.05 
20.75 
Brick red. 
1150 
10.6 
2.10 
8.60 
Brick red. 
1190 
12.6 
1.70 
7.50 
Brick red. 
1230 
12.6 
1.67 
5.80 
Brick red. 
1310 
13.6 
1.50 
6.10 
Brick red. 
JEFFERSON COUNTY 
Jefferson County lies in north Florida and extends from the north¬ 
ern boundary of the State to the Gulf of Mexico. It is underlain by the 
Alum Bluff formation in the northern part of the county and the Chat¬ 
tahoochee formation in the southern part. A heavy mantle of red, coarse, 
sandy clay covers most of the county. 
Several brick plants have formerly been operated in the county. 
Three of these, located near Monticello, have worked a sandy, jointed, 
surface clay. Another small plant worked a red surface clay on the 
Bishop Homestead, four miles south of Aucilla. Clays from each of 
these localities may be used for common brick. The Bishop clay is too 
far from transportation to be of commercial importance. 
