“Limestone is the rock from which lime is obtained. It is composed of carbonic acid and lime. To obtain the latter, the limestone is subjected to intense heat in a furnace or lime-kiln. The carbonic acid escapes, is dissipated in the air, and only the lime remains. In arable land limestone is found rather often in smaller or larger pieces, but more frequently as a fine powder which the eye can scarcely distinguish from the other constituents, especially clay. The water of rivers and other streams almost always contains a small proportion of dissolved limestone. Thence comes the thin layer of stone that accumulates little by little on the inner surface of bottles, coating the glass. Some waters contain enough of this dissolved limestone to deposit a mineral crust on objects immersed in them, as mosses and aquatic plants, and to obstruct their aqueducts. The clearest water, in which no foreign substance can be seen, absolutely none, nevertheless contains dissolved limestone, just as sweetened water contains invisible sugar. In drinking a glass of water we drink a little stone at the same time. Our body, in order to grow strong and increase in size, needs considerable calcareous matter for the formation of bones, which are to us what its solid framework is to a building. This material, so necessary to us, is not created by us; we obtain it from our food and drink. Water plays its part in furnishing this limestone, which it furnishes also to plants; they all contain a greater or less proportion of this mineral matter. “Calcareous soils are whitish from their chief constituent, chalk. Entirely sterile when the proportion of limestone is excessive, they are tolerably productive when clay is added. They are especially suitable for vineyards and for raising lucerne, sainfoin, and clover. Champagne and the south of France offer examples of this kind of soil. Its principal varieties are chalky soil, which is nearly sterile, containing as much as ninety-five per cent of chalk, and marly soil which is composed of clay and chalk. “The plant-life characteristic of calcareous soils comprises the box-tree, whose compact and fine-grained wood is so esteemed by turners; the wild cornel, whose red, olive-shaped fruit is one of the best-liked autumn products that nature offers us; and the alkekengi, or winter cherry, whose yellow berries are used for coloring butter. These berries are encased in a large, gorgeously red membranous bag.