244 
FLORIDA STATE GEOLOGICAL SURVEY. 
logical Survey prove that the Florida peats are well up to the average 
in fuel value. Both the details of the occurrence of the peat and the 
analyses of samples will accompany the report on peat when com¬ 
pleted. 
When it is remembered that in northern Europe more than 10 
million tons of peat are prepared and used for fuel annually, 1 it will 
scarcely be doubted that the large deposits in Florida will ultimately be 
used either for fuel or for other purposes for which peat with the 
improved processes of treatment may be adapted. 
DIATOMACEOUS EARTH. 
Diatomaceous earth consists of the tests of certain small plants 
known as diatoms. When pure it is a white powdery looking sub¬ 
stance. As it occurs in nature it contains often more or less im¬ 
purities. The diatoms themselves are minute in size and are visible 
only by the aid of the microscope. They are aquatic in habit and live 
in both salt and fresh water, and are particularly abundant in fresh 
water ponds. These minute plants secrete during life a siliceous cover¬ 
ing or test. After the death of the plant the test falls to the bottom. 
The accumulation of these tests forms in time the deposits known as 
diatomaceous earth. 
Diatoms seem to have been particularly abundant during the 
Tertiary period, large deposits formed during that time having been 
found in various parts of the world, especially in New Mexico, Ne¬ 
vada, California, and Oregon, as well as in Europe. 
The deposits found in Florida were formed in fresh water ponds 
and are of comparatively recent date. A deposit near Eustis which has 
been worked to some extent is in general appearance not unlike other 
peat bogs of that section. The diatomaceous earth is in fact intimate¬ 
ly mixed with the peat or muck and the material as taken from the 
bog has the appearance of peat of a grayish color. The method of 
treatment is to burn out the carbonaceous matter, the siliceous mate¬ 
rial remaining as a very fine, white powder. The deposit of peat in 
this bog according to soundings made by Dr. R. M. Harper has a 
thickness of twenty or more feet. Aside from the tests one observes in 
a mount of this material more or less silica resulting possibly from the 
silica contained originally in the stems and leaves of grasses. 
Infusorial earth is a term often used in commerce interchangeable 
with diatomaceous earth. Tripoli has frequently been used in Amer¬ 
ica to apply to a material which serves a similar purpose obtained 
from a bed of decomposed flint or chert. 
1 Davis, C. A. U. S. Geol. Surv. Bull. 379, p. 63, 1908. 
