“Sandy-clay soil is found in the valleys of great rivers. It is the most fruitful and the easiest to cultivate. Such are the soils of the Rhone valley, the valley of the Loire, and that of the Seine. It is still more fertile if it is flooded by the stream at high water. Then the river deposits a rich slime composed of clay and organic matter washed down by the current. “The soil of heathy or shrubby land is composed of fine sand and of humus from the decayed leaves of heather and other plants. It is only used for flower gardens, and furnishes an example of what might be called sand-and-humus soil. “Clay is a soil which, when moistened with water and thoroughly kneaded, becomes a soft and tenacious dough, suitable for molding into any desired shape. When perfectly pure it is white, and is known as kaolin, a rare substance of which porcelain is made. Plastic clays are those that are unctuous to the touch, forming with water a yielding mass that hardens with firing. They are used in making pottery. Smectite, or fuller’s earth, is a clay of very different character, not pliable when moistened, but very absorbent of grease and hence used by fullers for cleansing cloth of the oil left on it in weaving. Ochres are clays colored either red or yellow by iron-rust. They are used in coarse painting. Red chalk belongs to this class of clays. Marl is a mixture in variable proportions of clay and limestone. According to which constituent predominates, it is called argillaceous or calcareous. Subjected to the action of air and moisture, marl becomes flaky and crumbles to dust. Marl is used in agriculture to improve the soil. “A clay soil is quite the opposite of a sandy soil: water makes it swell and converts it into a sticky paste which clings tenaciously to farming implements. Once wet, it is cold, that is to say it dries very slowly. A spade can only divide it into dense clods slow to crumble in the air and not fit for receiving seed. The farmer must be careful to drain off the water and break up the ground by working it before and during frosts. It is improved by mixing with it sand, coal-ashes, and lime. Wheat flourishes better in a clayey soil than in any other kind. “Clayey soils are recognized by their vegetation. The wild plants peculiar to this kind of soil are colt’s-foot and danewort. Colt’s-foot is also called horse-foot from the shape of its leaves, the outline of which reminds one of a horse’s hoof. The leaves are white underneath. The flowers are yellow like little marigolds, and they appear at the beginning of spring before the leaves. Danewort is a kind of herbaceous elder of about half the height of a man. Its small white flowers are succeeded by berries full of a violet-red juice.” CHAPTER V DIFFERENT KINDS OF SOIL (Continued)