162 VLORIDA GEOLOGICAL SURVEY-I5TH ANNUAL REPORT


 This clay may be used to make an excellent grade of common building brick and similar structural materials. Rail transportation is not nearer than about three miles, but the Apalachicola River offers water transportation to points down that river and up the Flint and Chattahoochee Rivers in Georgia and Alabama. This clay has the following physical properties:

 Physical Properties of State Hospital River Field (Lab. No. o-8).
 Plasticity, judged by feel ............ Excellent.
 W ater of plasticity................. 26.50%
 Pore water ........................ 0.94%
 Shrinkage water ................... 25.56%
 Linear air shrinkage................ 8.1 %
 Volume air shrinkage............... 23.6 %
 Modulus of rupture, average ........ 301.1 pounds per -square inch.
 Slaking test ....................... 36 hours.
 Steel hard at cone 9.
 Fire tests:
 Temperature. Linear Shr. Absorption. Porosity. Color.
 Per Cent. Per Cent. Per Cent.
 950'C. 0.9 17.95 39.02 Brick red.
 1050 1.1 20.50 39.40 Brick red.
 1150 1.9 16.45 39.40 Brick red.
 1190 4.4 13.15 38.50 Brick red.
 1230 4.9 12.70 31.20 Brick red.
 1310 4.9 8.35 31.60 Brick red.
 1370 5.4 3.29 25.50 Brick red.
 1430 7.9 14.90 Brick red.

 The Ocklocknee Brick Company, located on the Seaboard Air Line Railway at Lawrence, uses a flood-plain clay. The deposit is five feet thick and is overlain by six inches of soil. The clay has good plasticity and bonding strength and presents no drying difficulties. It is now used in the manufacture of common brick. An excellent grade of common brick, hollow-block ware, and drain tile may be made from it. A series of compression tests made on the Ocklocknee Brick Company's product by the Birmingham branch of the Pittsburgh Testing Laboratory were as follows : Compression Tests on Ocklocknee Brick.

 HARD BRICK.
 Weight Dimen- Area, square Load, Unit load, pounds
 pounds. sons. inches. pounds. per square inch.
No. 1-4.1 3.6x7.8 28.08 78,900 2,810
No. 2-4.1 3.7x7.7 28.49 83,600 2,9r35
No. 3-4.2 3.7x7.8 28.86 88,500 3,067

 A verage ..................................................... 2,937