have not been found in the primary limestone, but its presence in the solid frequently affords a necessary mineral base for the accumulation of nitrous earth under plantation buildings, which in the absence of caves is found to be a valuable source of the niter supply. Good working caves should contain at least 5,000 cubic feet of earth. The nitrous earth, which usually covers the cave floor or fills up its side chambers in crevices, must be dry, and should yield 1 per cent. and upward of nitrates. Potash, wood, water within easy access outside are essential to the manufacture of niter from the natural deposits. These conditions are mentioned to explain the fact why out of so many known and explored case so few can be advantageously worked.
Referring to the niter district sin detail-in Virginia fifty contracts have been closed with private parties, some of whom have worked well, but from their slow progress and the frequent loss of caves by the enemy in Greenbrier and Monroe Counties, work has been undertaken on Government account as follows: One large cave in Tazewell, one is Giles, and six small caves in Wythe, Smyth, Pulaski, and Montgomery. These caves are in good working order and beginning to yield. The interruption from recruiting officers having generally ceased upon a large future yield is the scarcity of labor. The artificial production of niter has been commenced in Virginia near Richmond, the city affording material for 30,000 pounds at least per annum, which will be made use of if labor can be retained, which is almost impossible, for such work, so near the army. Beds have also been commenced at Petersburg.
In North Carolina the secondary limestone belt borders on the extreme western counties, where niter caves are few, small, and inaccessible. Our effective labors must be confined to the plantation earth in the tobacco and primary limestone counties. Several localities have been examined for niter beds on a large scale, but they do not present the facilities for work obtained elsewhere.
In South Carolina there is no known niter cave. The rich marls in the lower districts promise favorably for niter beds. One nitriary has been commenced by State authority at Columbia, one by Government agents near Orangeburg, and one on the Georgia side of the Savannah River near Augusta. At the last there are unusual facilities in climate, water carriage, and the supply of materials, organic and inorganic, for niter works of a permanent character upon the most improved European system.
In Georgia there are several niter caves int he northwestern counties-one in Bartow County, very valuable. This last, under imperative necessity and upon consultation with the adjutant-general of the State of Georgia-the State authorities having taken preliminary steps to seize the cave-was taken possession of by order of the Department on the 15th June, and has since been put in order and worked on Government account. During the last two weeks of private management the yield of the cave did nor reach eighty pounds per day; under Government management it was raised to 400 per working day, and would have been much higher but for the interruption of potash transportation on the Georgia railroads owing to the movement of General Bragg's army.
In Tennessee are several very large and rich caves. The most valuable are under hostile control. From Jonesborough down to Chattanooga fifteen more caves have been commenced on Government