Actual _chemical analysis_ confirms these deductions in regard to the constitution of soils. It shews that, in most soils, the presence of the several constituents of the ash of plants may be detected, though in very variable proportions. And following up its investigations, in regard to the effect of this difference in the proportion of the generally less abundant constituents of the soil, it establishes certain other points of the greatest possible importance to agricultural practice. Thus, it has found, for example, 1. That as a proper adjustment of the proportions of clay and sand is necessary, in order that a soil may possess the most favourable _physical_ properties—so that the mere presence of the various kinds of inorganic food in a soil is not sufficient to make it productive of a given crop, but that they must be so adjusted in quantity that the plant shall be able readily and at the proper time to obtain an adequate supply of each. 2. That when a soil is particularly poor in certain of these substances, the valuable, cultivated corn crops, grasses, and trees, refuse to grow upon them in a healthy manner, and to yield remunerating returns. And, 3. That when certain other substances are present in too great abundance, the soil is rendered equally unpropitious to the most important crops. In these facts the intelligent reader will perceive the foundation of the varied applications to the soil which are everywhere made under the direction of a skilful practice, and of the difficulties which, in so many localities, lie in the way of bringing the land into such a state as shall fit it readily to supply all the wants of those kinds of vegetables which it is the special object of artificial culture easily and abundantly to raise.