DIFFERENT KINDS OF SOIL (continued.)

Too Long; Didn't Read

“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, [26]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.