184 
FLORIDA GEOLOGICAL SURVEY— 15TH ANNUAL REPORT 
Both of these clays are cream-burning and retain a soft, porous tex¬ 
ture up to their fusion points. The top clay melts at cone 12 and the 
lower one at cone 9. Neither of them are desirable for the manufacture 
of high-grade clay products. A light, soft, porous structural material of 
low strength may be made from the lower clay, but very careful grinding 
and mixing would .be necessary. Both of these clays are high in soluble 
salts. The upper one contains 24.4 per cent lime and 6.63 per cent mag¬ 
nesia, as may be seen from the analysis given on the next page. 
Its physical properties are: 
Physical Properties of IV. J. McLaughlin Top Clay (Lab. No. 0 - 72 ). 
Excellent. 
Plasticity, judged by feel... 
Water of plasticity. 
Pore water . 
Shrinkage water . 
Linear air shrinkage....... 
Volume air shrinkage. 
Modulus of rupture, average 
Slaking test. 
Overfires at cone 12. 
29.10% 
0.19% 
28.91% 
4.80% 
12 . 10 % 
265.9 pounds per square inch. 
10 minutes. 
Fire tests: 
T emperature. 
Linear Shr. 
Per Cent. 
A bsorption. 
Per Cent. 
Porosity. 
Per Cent. 
Color. 
950°C. 
0.8 
6.19 
67.20 
Cream. 
1050 
1.2 
5.87 
66.80 
Cream. 
1150 
2.2 
5.30 
63.50 
Cream. 
1190 
5.2 
3.87 
54.50 
Cream. 
1230 
3.2 
3.93 
57.50 
Cream. 
1310 
2.2 
4.05 
60.10 
Cream. 
The lower clay contains 9.1 per cent lime and 5.54 per cent mag¬ 
nesia, as may be seen from the analysis given below. Its physical proper¬ 
ties are: 
Physical Properties of JV. J. McLaughlin Bottom Clay (Lab. No. 0 - 10 ). 
Plasticity, judged by feel... 
Water of plasticity. 
Linear air shrinkage. 
Volume air shrinkage. 
Modulus of rupture, average 
Slaking test .. 
Overfires at cone 9. 
Excellent. 
38.40% 
12.70% 
36.95% 
544.9 pounds per square inch. 
3 days. 
Fire tests: 
Temperature. 
Linear Shr. 
A bsorption. 
Porosity. 
Color. 
Per Cent. 
Per Cent. 
Per Cent. 
950°C. 
0.2 
26.45 
48.75 
Cream. 
1050 
2.3 
26.20 
47.50 
Cream. 
1150 
4.8 
25.80 
43.30 
Cream. 
1190 
4.3 
20.75 
43.40 
Cream. 
1230 
6.3 
16.75 
