UIHistories Project: A History of the University of Illinois by Kalev Leetaru
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Repository: UIHistories Project: Board of Trustees Minutes - 1871 [PAGE 199]

Caption: Board of Trustees Minutes - 1871
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191 in them. A soil containing such an admixture of these substances as will mutually compensate the defects of each—which is neither too wet in rainy seasons, nor too dry and hard in drouths—which, by cultivation, readily becomes porous, so that roots can easily penetrate it, and the atmosphere circulate through it—is best suited for agricultural purposes, and will yield the most remunerative returns. The clay in such a soil is even more effective in absorbing the constituents required by plants than when pure, because the water containing these substances is more readily absorbed by such a soil than by a purely clayey one. This is illustrated by what formerly took place here on the burning over of the prairie. The country, of course, was covered with a layer of ashes, rich in potash, and when the rain fell too rapidly to be all absorbed, it flowed from the surface, carrying the potash with it, and imparting to streams a strong, alkaline property. Had the water passed through the soil, the clay would have absorbed most of the alkali, and retained it for future use. For the same reason but little alakaline matter is usually found in the water of drains. In the decomposition of the vegetable and mineral matter of porous soils, the ammonia and other alkaline substances are absorbed by the clay; and it is clay also to which is due the decolorizing and deodorizing nature of soils, a property which, in consequence of a special application in the form of earth closets, has, of late, been pressed on the public attention as something new. But a few years since this absorbent property of soils was specially investigated by Way. H e found that sewer, and other foul water, when filtered through a layer of porous earth, thirty-four inches thick, was entirely deprived of its smell, its ammonia, potash and phosphoric acid; in fact, that all substances essential to the nourishment of plants are absorbed and retained to such an extent, that a soil, ten inches thick, when saturated in this way, would contain twenty times as much nutritious matter as is usually spread over it for fertilizing purposes. Could all the sewer water, now passed from cities into rivers and thus lost, be distributed over the soils of the adjacent country, what an immense amount of plant-food would be utilized, and what an increase of harvests would accrue through the agency of this property of soils. If we seek for the cause of this absorbent property of clay, we shall find it, probably, in a powerful surface attraction, similar to that by which gasses and coloring matters adhere to the surface of porous charcoal. Some have supposed, however, that the action is more chemical than physical in its nature, and that the absorption of the alkalies is accompanied by the formation of insoluble silicates, resembling the