[10] A ruble is equal to 5 livres, or 1 dollar Spanish.
_On a Rotation of Crops, and the most profitable mode of collecting, preserving and applying Manures._
(Communicated to the Albany County Agricultural Society.)
Of manures which may be termed fossils we will mention the various kinds of calcareous substances, the stony matter called pyrites, coal, salt, peaty substances, silicious and aluminous earths. Limestone, gypsum, chalk and marle, are the calcareous substances we shall notice, and each in their order.
Limestone, (carbonate of lime,) has always more or less aluminous or silicious earth in its composition. Frequently also it contains magnesia. Limestone of this latter description, when calcined, makes what the English farmers call _hot_ lime, which is more powerful in its effects, and therefore less of it should be applied at once to the soil. That without any mixture of magnesia is considered more durable in its operation, but less powerful. Magnesian limestone is known by its effervescing but little when plunged in nitric or other acid, while limestone that is not magnesian, when thus immersed produces a strong effervescence. The magnesian, also, when immersed in diluted nitric acid, or aqua fortis, renders the liquid of a milky appearance. It is usually of a brownish or pale yellow colour. Being more caustic when calcined, than common limestone, it is more efficacious in decomposing peaty earths, and is best adapted for soils which have too much either of peaty or vegetable matter in them.----Where lands have been injured by too plentiful an application of this lime, peaty earth should be applied to them to correct the evil.
The trials of lime in this country have been quite limited, and confined mostly to the middle states, particularly Pennsylvania. It has usually been applied there at the rate of about forty bushels to the acre; but whether the lime used there is magnesian, we have never understood. Lime may be applied as a top dressing or mixed with the soil. Its application has been found most successful when the first succeeding crop was Indian corn; afterwards wheat is grown to advantage. Instances are mentioned in the memoirs of the agricultural society of Philadelphia, where gypsum had no effect on worn out lands till they were first manured with lime.