A PRELIMINARY REPORT ON CLAYS OF FLORIDA 123

in temperature when in use fairly well without excessive losses from cracking.
 A mixture of equal parts of the upper white clay and the lower reddish clay in this deposit as used by the Campville Brick Company has the following physical properties:
 Physical Properties of Campville Brick Company Clay (Lab. No. b-52).
 Plasticity, judged by feel............ Excellent.
 Water of plasticity ................. 27.45%,
 Pore water ......................... 2.55% ,
 Shrinkage water ................... 24.90%.
 Linear air shrinkage ............... 11.5 %
 Volume air shrinkage ............... 28.3 %
 Modulus of rupture, average........ 400.2 pounds per square inch.
 Slaking test ....................... 24 hours.
 Fire tests:
Temperature. Linear Shr. Absorption. Porosity. Color..
 Per Cent. Per Cent. Per Cent.
 9500C. 0.5 14.69 33.20 Pink.
 1050 0.5 15.81 33.60 Light pink.
 1150 1.0 13.79 32.40 Light brown.
 1190 1.0 13.66 30.20 Yellowish brown.
 1230 1.0 12.40 29.40 Yellowish.
 1310 1.0 13.28 30.10 Yellowish.
 In the northeast part of the county in the region about Waldo and Melrose a brown sandy jointed clay is exposed in numerous places. It is only suitable for a low grade of common brick.
 A blue-gray jointed clay is exposed in Hatchett Creek at the crossing of the Seaboard Air Line Railway (Cedar Key Division). This clay has an excessive air- and fire-shrinkage ana1 cracks slightly in firing. It is of little value for fired products, except perhaps a poor grade of common brick. Its physical properties are:
 Physical Properties of Hatchett Creek Clay (Lab. No. 0-47).
 Plasticity, judged by feel............ Poor.
 Water of plasticity................. 39.30%
 Pore water ........................ 3.08%
 Shrinkage water .................... 36.22%
 Linear air shrinkage ................ 15.5 %
 Volume air shrinkage............... 44.7 %
 Modulus of rupture, average........ 208.3 pounds per square inch.
 Slaking test ....................... 2 minutes.
 Steel hard at cone 1.
 Fire tests:
Temperature. Linear Shr. Absorption. Porosity. Color.
 Per Cent. Per Cent. Per Cent.
 950*C. 6.5 8.42 20.50 Pink.
 1050 7.5 9.57 21.75 Light brown.
 1150 8.5 6.89 18.30 Dark brown.
 1190 9.5 1.93 16.50 Brown.