18 FLORIDA GEOLOGICAL SURVEY-SEVENTH ANNUAL REPORT. 
ing and burning shrinkage. The clay retains a porous structure at 1250 degrees 
C. (2282 degrees F.), and cannot be used in the manufacture of vitrified ware 
burned in commercial kilns. The clay may be used in the manufacture of com¬ 
mon and building brick. 
Sample No. 2, Washington County. The clay possesses good working plas¬ 
ticity and molding behavior; water of plasticity, 36%; a few cracks developed 
by drying; linear drying shrinkage, 9.42%; linear burning shrinkage, at 850 de¬ 
grees C., 0.55% ; at 1010 C., 1.57% ; at 1130 C., 7.75% ; at 1250 C., 8.10%. A good 
light buff color is developed by burning; per cent porosity, at 850 degrees C., 
36.80% ; at 950 C., 35.30%; at 980 C., 34.75%; at 1010 C„ 34.50%; at 1040 C., 
30.75% ; at 1070 C., 25.70% ; at 1100 C., 22.45% ; at 1130 C., 19.70% ; at 11.60 C., 
17.95%; at 1190 C., 15.70%; at 1220 C., 14.60%; at 1250 C., 12.55%. A buff 
burning clay of good plasticity and a relatively high drying shrinkage. May be 
used in the manufacture of buff colored face brick, although care must be ex¬ 
ercised in drying. The clay must be burned above 1250 degrees C. in order to 
attain low porosity. 
Sample No. 3, Santa Rosa County. The clay has good working plasticity 
and molding properties; water of plasticity, 28.90%; no drying difficulties; lin¬ 
ear drying shrinkage? 6% ; linear burning shrinkage, at 850 degrees C., 0.64% ; 
at 1010 C., 0.21% ; at 1130 C., 1.44% ; at 1250 C, 1.17% ; burns to salmon color, 
changing to buff at higher temperature; per cent porosity, at 850 degrees C., 
35.30% ; at 950 C., 35.80% ; at 980 C., 36.20% ; at 1010 C., 34.86% ; at 1040 C., 
33.60%; at 1070 C., 32.15%; at 1100 C., 31.10% ; at 1130 C., 29.55%; at 1160 C., 
29.05% ; at 1190 C., 28.80% ; at 1220 C., 28.05% ; at 1250 C., 27.30%. A clay pos¬ 
sessing good working and drying qualities but which cannot be vitrified at the 
burning temperatures of commercial kilns. Test pieces burned to 1250 degrees 
C. are easily cut by a knife. This clay is of value only in the manufacture of 
porous common building brick, etc. 
Sample No. 4, Escambia County. Appears to have good working behavior 
and plasticity; water of plasticity, 21.95%; drying behavior satisfactory; linear 
drying shrinkage, 5.75% ; linear burning shrinkage, at 850 degrees C., 1.28% ; 
at 1010 C., 0.05% ; at 1130 C., 0.26% ; at 1250 C., 1.16% ; color after burning, light 
to dark red; per cent porosity, at 850 C, 28.65% ; at 950 C., 29.30% ; at 980 C., 
28.20% ; at 1010 C, 27.90% ; at 1040 C, 27.75% ; at 1070 C, 25.85% ; at 110O C., 
26.95%; at 1130 C., 25.70%; at 1160 C., 27.95%; at 1190 C., 26.80%; at 1220 C., 
19.90%; at 1250 C., 20.20%. A clay possessing good working and drying be¬ 
havior, but one which retains a porous structure a-t temperatures as high as 1250 
degrees C. The clay is suitable for common and face brick, etc., but not for 
paving brick or other vitrified ware. 
Sample No. 5, Walton County. Plasticity and working properties good; 
water of plasticity, 28.30%; drying behavior satisfactory; linear drying shrink¬ 
age, 6.75% ; linear burning shrinkage, at 850 degrees C., 0.34% ; at 1010 C., 
0-35%; a t H30 C., 2.17%; at 12.50 C., 2.25%; color after burning, salmon to 
light red; per cent porosity, at 850 degrees C., 33.60% ; at 950 C., 33.20% ; at 980 
C., 35.40% ; at 1010 C., 34.35% ; at 1040 C, 32.80% ; at 1070 C., 30.50% ; at 1100 
C, 29.85% ; at 1130 C., 28.60% ; at 1160 C., 27.55% ; at L190 C., 27.80% ; at 1220 
C., 27.10% ; at 1250 G, 26.00%. A red burning clay having good working and 
drying behavior, but retaining a porous structure. Test pieces burned to 1250 
C. are easily scratched by a knife. This clay is suitable for the manufacture of 
porous common and building brick. Not practical to vitrify in commercial kilns. 
Sample No. 11, Duval County. Fairly plastic, fairly good working qualities; 
