Cretaceous Clays of Middle Georgia. — Ladd. 243 
mous tensile strength of the air dried briquettes. Nevertheless 
the presence in these of a considerable amoinit of fluxing im- 
purities renders them of small commercial value, with the ex- 
ception always of the Columbia brick clays. 
The Potomac clays are valuable for two reasons. First, 
because they are extremely pure as regards fluxing impurities, 
which adapts them especially for the manufacture of refractory 
wares, and in the second place because, over large areas, these 
clays, otherwise pure, are also wholly free from grit or sand, 
and because they are friable and easily broken up into an inco- 
herent mass of fine particles, while they are practically as white 
as snow. They are thus fitted for the demands of the wall 
paper trade, the manufacturers of w-hich are large consumers 
of this kind of clay, paying as high as from $8 to $12 per ton. 
In South Carolina a few miles from Augusta, Georgia, this 
clay is extensively worked for the wall paper industry, while 
in Georgia development is going on and shipments being made 
from at least three different localities along the fall line. One 
company has opened a bed in the vicinity of Butler, another at 
Dry Branch, near Macon, and a third in Wilkinson county, at 
Lewiston. 
The clay beds are all easily worked. In some cases in old 
fields they are entirely free from stripping and the white chalk- 
like clay is exposed at the surface. In other cases an over- 
burden of Lafayette sand and gravel occurs, varying in thick- 
ness from 12 to 20 feet. The overburden, where necessary, is 
removed in wagons until the surface of the clay is exposed 
over a considerable area. This surface is then carefully scraped 
and swept until entirely free from the presence of grains c^f 
sand. The clay is then worked in open cuts, and sorted out 
under the direction of trained men. That which contains 
sandy impurities is entirely discarded, and the remainder class- 
ified according to the density and freedom from color (the 
pure white being the most valuable). Three colors are sold t(^ 
the wall paper trade, pure white, that which is faintly grayish, 
and a third grade having a slightly grayish or bluish tint. The 
clay is stored in drying sheds and after being thoroughly dried 
is broken up and packed solidly into enormous casks for 
shipment. The clay is usually cream colored when first taken 
from the pit, always becoming lighter and usually becoming 
