or five dollars a ton. This would make the first cost reasonable enough, but it cannot be less than doubled after adding the expenses of transportation to a distance. But though possessing a larger percentage of calcareous matter than stone lime, yet nothing of the kind ever acted better on our soils than what was formerly brought from the North River, being, with the exception of sand, free from all extraneous ingredients, such as magnesia, which is found in so large proportion in the Washington lime, rendering it oftentimes hurtful instead of beneficial to the land. Whenever the lands on our river borders shall be brought again into extensive cultivation, the North River lime will doubtless come into as great request as formerly.

It would be doing injustice to the name of a distinguished agriculturist and a man of genius to withhold in this connection a reference to the labors and experiments of the late Edmund Ruffin. His fame is, in fact, indissolubly associated with this subject, for he was the pioneer in the work, devoting for years a mind of extraordinary activity to efforts, both by example and precept, directing public interest in this channel of improvement. A small number of experiments had been made in marling in James City County, as early as 1816, or perhaps earlier, but without being conducted with any intelligent purpose. In ignorance of these, however, Mr. Ruffin made his first experiment in 1818, to the trial of which he was led altogether by theoretical views and by reasoning on the supposed constitution of the soil, as well as the known constitution of the manure. This was on his farm at Coggin's Point, on James River, in the county of Prince George. It extended over an area of about fifteen acres, but by 1821 the area wàs increased to eighty acres, and was subsequently continued, until within a few years all the arable land on the farm, say six hundred acres, was thoroughly marled. The result was marvelous, and soon had the effect of stimulating others to engage in the work, until the practice of marling became general among intelligent farmers throughout tide-water Virginia. In all cases wherein any thing like an ameliorating rotation was followed, the crops were quadrupled and the land put into a course of permanent improvement. Proverbially slow as agricultural progress has ever been, yet in the course of forty years, from a very small beginning, a vast revolution was effected, and all through the agency of one inan of comprehensive views and untiring energy, whose services in a noble pursuit entitle him to rank as a public benefactor.

Mr. Ruffin's writings on the subject of marl were quite voluminous. For ten years he conducted the Farmers' Register, an agricultural journal, issued monthly at Petersburg from 1833 to 1843, in which the subject of marl occupied a prominent place. But his fame as a writer is chiefly built on his Essay on Calcareous Manures, an octavo volume of three hundred pages, which took position as a standard work immediately on its publication.

THE LIMESTONE REGION.

Limestones occupy the valley of Virginia throughout its length and breadth. Some of them are of great purity and yield limes equal to any from the north. Some, too, when burned and ground, yield admirable hydraulic cements. These last, however, would not make limes suited to agricultural purposes. Limestones also occur in several places west of the great valley. The Warm Spring Valley is a limestone formation, and large areas in Highland County are covered with it; while still further west, in what are now the border counties of West Virginia, lime

stones, the same that make Kentucky so great a grazing country, abound almost everywhere, and impart to this whole section its distinctive feature as one of the finest grazing countries in the world.

It would seem, from all we can gather, that very little lime has been used in the valley as a fertilizer. But it does not follow from this that applications of lime to limestone lands are not beneficial. On the contrary, the almost universal use of lime in Lancaster and other limestone counties in Pennsylvania, where high farming is the rule rather than the exception, demonstrates its great value in promoting the fertility of the soil. The experience, indeed, of some of our own valley farmers, who have used lime, goes to prove the same thing. East of the Blue Ridge, in what is termed the Piedmont division of the State, a belt of talcose and mica slate, of varying width, traverses the counties of Fauquier, of Culpeper, Orange, Louisa, Albemarle, Buckingham, Nelson, Amherst, Campbell, Pittsylvania, and Franklin, following a direction mainly parallel to the mountain crests, and consequently running northeast and southwest. A line traced on the State map from the mouth of Summerduck Run, on the Rappahanock, through Orange Court House, Gordonsville, Warminster, on the James, to the mouth of Archer's Creek, and prolonged to the southwest into Franklin County, would indicate approximately the position and direction of this belt of talcose rocks, which accompanies the limestone. The limestones occur somewhat irregularly along this line, interrupted or in layers; not continuous, but outcropping at various places where they have been quarried either for building or burning to lime. From a short distance above Scottsville up nearly to Lynchburg the James River meanders through this belt, and consequently we find the limestone exposed at numerous points along the river, and favorably located for quarrying and water transportation. If lime suitable for agricultural purposes can be obtained from it, this calciferous belt, running through a section the soils of which are as a rule deficient in lime, must prove an incalculable blessing to farmers. Various analyses of these limestones, made by Professor Rogers while State geologist, demonstrate their value for all the purposes to which lime may be applied. Considerable variation in the constituents are reported in specimens from different localities, some yielding a lime of excellent quality, some being true hydraulic limes, while others contain a considerable proportion of magnesia. How far the presence of this mineral may affect its value for agricultural purposes the writer is not prepared to say. A belt similar to the one described traverses the northwest side of Fauquier and Loudon, lying along the west side of Bull-Run Mountain. At several localities in this belt the limestone has been burned, and is said to have yielded lime of good quality for building purposes, but we have no information that it has been used as a fertilizer.

It is within the recollection of the writer that the owners of limekilns along James River, at its intersection with the belt above described, were at one time ready to make contracts with the farmers living below for the delivery of agricultural lime at their landings on the canal. Only a small quantity, however, was taken, and no valuable result was ever reported. It was believed that the soils near the river did not require it, and thus the use of lime throughout the district, from the Blue Ridge to tide-water, seems to have made no progress whatever. At the same time the soils are believed to be destitute of any calcareous ingredient, while a portion of them evidently comes under the head of "acid" soils, according to the nomenclature of Mr. Ruffin, as is indicated by the growth of sorrel, broomsedge, huckleberry bushes, old-field pine, and

other sour plants. But generally the soils of all this region are highly improvable, resting for the most part on a basis of red or yellow clay. The red soils of Albemarle and Goochland are proverbial for their fertility. Clover grows well wherever the land has not been exhausted, and plaster has a fine effect. Should lime ever become accessible at a moderate cost, this may be made one of the finest, as it is one of the most salubrious, districts in the State.

According to all analogy we should expect to find limestone accompanying the coal measures of Chesterfield, Henrico, and Goochland. But not a trace exists, with the exception of a thin crystalline deposit of pure carbonate of lime, resting immediately on the granite which forms the bed of the coal basin. This extensive coal-field is thought by geologists to have been deposited long subsequent to those of other coal districts, and therefore not properly belonging to the carboniferous era. It affords the only instance, it is believed, in which the coal is superimposed immediately above the granite. This is not uniformly the case, however, on account of the frequent and violent dislocations that are found to occur in every part of the basin yet explored, and which in the sinking of a shaft render the striking of a seam as much a matter of chance as of science. Thus far, coal has been raised only on the eastern and the western boundary of the basin, which is from eight to ten miles in width; and, from the great dip of the strata, it is hardly possible it will ever be raised from the middle, not even by means of drifts. Already there are numerous pits from seven hundred to eight hundred feet deep within a mile of the outcropping.

The fine coal which accumulates at the mouths of the shafts has been used for agricultural purposes, and not without benefit. But the effect is perhaps only mechanical, by improving the texture of heavy soils, or contributing to the warmth of those which are cold by a freer admission of the sun's rays.

PLASTER.

The only extensive deposit of gypsum in the State, as far as we have any knowledge, is situated in the extreme southwestern portion, in the counties of Smyth and Washington. It is found in the valleys of the North Holston River and of Walker's Creek, between Walker's Mountain and Clinch Mountain, and stretches along these valleys for forty miles in a nearly east and west direction. The plaster occurs as boulders, some of which are of immense size, imbedded in clay. The deposit is believed to have great depth, and practically it may be regarded as inexhaustible. The beds have not been worked to any great extent, though enough has been taken out to supply the wants of the surrounding country. It has found its way also along the Virginia and Tennessee railroad as far as Liberty, in Bedford County, and from this and other points on the road over the mountain into Botetourt, and some is sent in boats down the Holston River. There can be no doubt that with convenient access to a market by railroad or water, with transportation at reasonable rates, the whole State, above tidé water at least, could be supplied with plaster at prices considerably less than for Nova Scotia plaster. The beds are several miles from the railroad, so that at present the plaster has to undergo the expensive process of hauling in wagons; but it is understood that efforts are being made to get a branch road, or tram-way, to the banks. An analysis by Professor Gilham makes this plaster equal in all respects to the Nova Scotia.

CONCENTRATED FERTILIZERS IN THE SOUTH

ERN STATES.

THE PECULIAR WANTS OF SOUTHERN AGRICULTURE.

Cotton planting, the product of which is largely exported and which demands constant tillage, and the occasional heavy rains falling on light plowed ground easily washed, tends powerfully to denude and impoverish the soil. As no cotton, grain, or tobacco can be raised without cultiva tion, and frequent heavy rains are as distinctive in their character as any other feature of our climate, fertility can be maintained in long-cultivated fields only by restoring to the soil in some way the elements of crops removed partly by washing rains and partly by fertilizing atoms consumed in the growth of cultivated plants. Hence, planting industry in a semi-tropical climate requires for its highest usefulness and success far more manure derived from sources outside of the plantation than ordinary farming, or mingled grass and grain culture with stock husbandry. Under the latter system the farmer has superior advantages for the home production of fertilizers from live stock, that give a profit independent of their manure. Fields seeded to permanent grass or in clover are generally exempt from injurious surface washing, while all the fertilizing substances contained in a rich turf, and in the valuable roots, stems, and leaves of clover, are drawn, in part at least, from the atmosphere and the deep subsoil. To exclude from cotton plantations all clover, grass, culture and stock growing is not wise, unless one may command at a low price concentrated commercial manures that will at once maintain the fruitfulness of every field and return a satisfactory profit. Commendable efforts have been made, and are still in progress and increasing, to supply manures of this character. They are essentially such elements of fertility as disintegrated rocks yield to the best clay, sand, and soils. Such plant-food as rain water and the atmosphere supply over every poor field as generously as over those most productive, are to a large extent left out. Concentration means the exclusion of all atoms in manure that experience proves to be of less value than those retained. A fertilizer that has no greater value, pound for pound, than common yard and stable manure, will not bear long and expensive transportation, if the planter obtained it in the first instance for nothing. Concentration, therefore, is a matter of the greatest practical importance where land by the hundred million acres, remote from commercial centers, is to be fertilized by commercial manures. As far as the planter, farmer, or stock raiser sends a bale of cotton, barrel of flour, or fat steer to market, which takes from the soil a part of its indispensable phosphates, sulphates, potash, and other bases, the principle of restitution should be applied and compensation made, if need be, by the return of the fertilizing substances named. A nation of farmers and planters who cultivate poor land without manure must, from the necessities of the case, support half of its entire popula tion in poverty, ignorance, and a low standard of material and moral comfort. Unproductive labor enriches no one, while it denies that "hope of reward" which is the very life and inspiration of happy indus

try. A nation heavily in debt can ill afford to cultivate land too poor to return more than a bare subsistence to the millions that live upon it; and it is still worse economy to impoverish, from the lack of manure, the fruitful lands that remain to us of our noble inheritance. Not only our cotton growing interest in the South, but our wheat and corn growing interests everywhere, demand the raw material for making crops at the cheapest rate it can be furnished by the best talent, science, and art in the country. Let us examine some of our resources in the planting States to supply the essential food of plants.

SALTPETER CAVES IN THE SOUTH.

It is a historical fact of no inconsiderable agricultural importance that, during the last war with Great Britain, when our coasts were blockaded, saltpeter was made for gunpowder from the nitrate of lime taken from the Mammoth Cave in Kentucky. Similar caves, but less in extent, in North Alabama, Middle and East Tennessee, and Virginia, furnished a large but unknown quantity of this nitrate during the recent civil war. One of these niter-producing caves exists on the farm of Dr. Lee, about twenty-five miles below Knoxville, and another on the farm where he resides, near the French Broad River, in Knox County. The successful use of nitric acid, in combination with potash, soda, lime, and magnesia, as a fertilizer, leaves no room for doubt that a pound of nitrogen in this form is not less valuable as plant-food than an equal weight in the form of ammonia. Therefore, whoever can produce the nitrate of lime, in a cave or elsewhere, may produce the most valuable constituent in Peruvian guano, an imported manure worth eighty dollars a ton in Baltimore, and ninety-five dollars a ton in several southern cities. Deprive this expensive manure of its nitrogen, and its market value will fall at once to less than half of its present price, although the average quantity of nitrogen contained in it does not exceed twelve per cent.

As a source of assimilable nitrogen, nitrification is a matter that well deserves the study of every planter and farmer. It is not more certain that common mold and toad-stools grow on a dung heap than that saltpeter will grow at the expense of atmospheric nitrogen and oxygen, under favoring conditions. Nitric acid probably exists more abundantly in Chili and Peru, in combination with soda as cubic-niter, than in any other countries; and it is found under conditions that forbid the idea that the acid has a vegetable or animal origin. Nitrification appears to resemble combustion, with this difference: carbon, hydrogen, sulphur, and phosphorus, burn and form acids without the aid and presence of any base to unite with the acid generated; while the combustion of nitrogen with oxygen requires the aid of a present alkali or alkaline. base to combine with and take up nitric acid as fast as it is formed. Decaying animal or vegetable matter liberating nascent nitrogen in the presence of lime in our caves, of soda in Chili, and potash in many places, may be, and probably is, necessary to start the formation of nitric acid; but nitrification once going on, with an abundant supply of oxygen and nitrogen present, and lime greedy to consume the acid as soon as formed, much more niter appears in the result than the organic matter will account for by the nitrogen supplied. Precisely what varying conditions extinguish the chemical action called nitrification are not known. The subject loses some of its practical importance on limestone land, from the fact that with clover and a little plaster we can draw assimilable nitrogen directly from the atmosphere cheaper in