GEOLOGY BETWEEN APALACHICOLA AND OCKLOCKNEE RIVERS. 21 
series of hydrous aluminum silicates. These silicates differ in 
chemical composition, but are. similar in that they all possess an 
amorphous colloidal structure. These colloidal silicates possess the 
power of absorbing and retaining organic coloring matter, thus 
bleaching oils and fats.” 
Uses : — The Florida fullers earth finds its chief use in filtering 
mineral lubricating oils. According to Day, “The. common prac- 
tice with these mineral oils is to dry the earth carefully, after it 
has been ground to 60 mesh, and run it into long cylinders, through 
which the crude black mineral oils are allowed to percolate, very 
slowly. As a result the oil which comes out first is perfectly water- 
white in color, and markedly thinner than that which follows. The 
oil is allowed to continue percolating through the fullers earth until 
the color reaches a certain maximum shade, when the process is 
stopped, to be continued with a new portion of earth. The oil is 
recovered from the spent earth.”* It is also used to some extent 
for lightening the color of cotton seed oil, and lard oil, although 
the English fullers earth is better for these purposes. The original 
use of fullers earth, that of cleaning, is now one of the minor uses. 
It is said to be used in the manufacture of some soaps. It is used 
in cleaning furs and by druggists as an absorbent. 
Methods of Mining : — Originally the overburden in the Gads- 
den county fullers earth mines was removed by pick and shovel. 
At the present time, however, the overburden is removed chiefly by 
steam power and hydraulicking. The depth of overburden that 
can be profitably removed is determined entirely by the depth and 
character of the fullers earth deposit. The overburden removed 
in the mines which are now being worked varies from one or two, 
to twenty or twenty-five feet. The greater part of this overburden 
is more or less decayed and residual in character and is readily re- 
moved. With some of the harder material, loosening by blasting 
becomes necessary. 
The fullers earth itself is mined in the open pit by pick and 
shovel, and by steam shovel, being loosened when necessary by 
blasting. From the pit it is loaded by shovel into “dummy” cars 
and is drawn either by cable or by small engine to the plant nearby. 
At the plant the fullers earth is taken to the store house. The 
*U. S. Geol. Surv., 21st Ann. Rept., pt. 6 (cont.), p. 592, 1901. 
