258 
FLORIDA STATE GEOLOGICAL SURVEY. 
of minerals it is often difficult to make a satisfactory determination of 
the individual mineral constituents. 
Chemical Constituents:—There is a wide range in variation in the 
chemical constituents of different fullers earths, or fullers earth from 
different localities. The range of individual constituents may be in¬ 
ferred from the accompanying analyses. 
ANALYSES OF FULLERS EARTH FROM VARIOUS LOCALITIES. 
I. 
II. 
III. 
IV. 
V. 
VI. 
Silica (SiO,) .. 
.62.83 
67.46 
58.72 
50.36 
74.90 
63.19 
Alumina (Ah0 3 ) . . 
. . . . .10.35 
10.08 
16.90 
33.38 
10.25 
18.76 
Ferric Oxide (FeX) 3 ) ........ 
. .. .. 2.45 
2.49 
4.00 
3.31 
1.75 
7.05 
Lime (CaO) ... 
. 2.43 
3.14 
4.06 
1.30 
0.78 
Magnesia (MgO) ............ 
. 3.12 
4.09 
2.56 
2.30 
1.68 
Potash (ICO) ... 
Soda (NaoO) ......... 
. 0.74 
. 0.20 
-4 
2.11 
.88 
1.75 
JO.21 
11.50 
Water (HoO) ...’.. 
. 7.72 
5.61 
8.10 
12.05 
5.80 
7.57 
Moisture ... 
. 6.41 
6.28 
2.30 
1.70 
No. I. From Gadsden County, 
Florida. 
U. S. Geol: Sur. 
17th 
Ann. Rept., pt. 
iii (cont.), page 880. 
No. II. From Decatur County, Georgia. Ibid. 
No. III. From Fairburn, S. D. Ibid. 
No. IV. Glacialite, Enid, Okla. G. P. Merrill, Non-metallic Minerals. U. S. 
Nat. Mus., Rept. for 1899, p. 337, 1901. 
No. V. From Sumter, S. C., U. S. Geol. Surv., Min. Reso., 1901, p. 933, 1902. 
No. VI. From Alexander, Ark. Branner, Amer. Inst. Min. Eng. Trans. XXVII. 
p. 62 1898. Ries, Clays, p. 465, 1906. 
Physical Properties:—The most distinctive physical property of 
fullers earth is that of clarifying oils. 
Test for Fullers Earth:—Fullers earth varies in color. That found 
in Florida is mostly light buff, brownish or yellowish, or olive green, 
gray or blue. It is not readily distinguished in general appearance 
from other clays. It is light and porous and when dry adheres firmly 
to the tongue, but some other clays are also adhesive. A practical 
test of fullers earth is necessary in order to determine its value. A 
test may be made by the use of a glass tube p 2 to 1 inch in diameter 
and 2 to 3 feet long. To make the test, support the tube in an erect 
“position, the lower end being plugged with asbestos fiber. The earth 
is powdered and packed into the tube. A mineral oil is then passed 
through .it. If the clay is a fullers earth the oils will be more or less 
perfectly clarified, depending upon the quality of the earth. It is 
reported that a fullers earth that will clarify a mineral oil may not 
affect a vegetable oil, while an earth used to clarify a vegetable oil 
may be unsatisfactory when applied to a mineral oil. A theory of the 
action of fullers earth in clarifying oils is given by Porter as follows 
