Difference Between Limestone And Burnt Lime
Limestone is carbonate of calcium, usually known as carbonate of lime. When in the form of crystalline marble it is almost pure, but common limestone usually contains a greater or less amount of sand, clay, or other impurity. When limestone is heated carbonic acid gas is driven off and calcium oxide is left. This is quick-lime, which readily takes up water and forms caustic lime.
One hundred pounds of good limestone will yield about 561b. of pure fresh-burned lime, and when this is slaked it will yield about 741b. of caustic lime. When the burnt lime is left exposed to the air or is added to the soil it rapidly changes back again to carbonate of lime, and the only object of slaking lime before applying it to the land is to obtain the material in very fine powder. This object can also be obtained by grinding the ‘ quicklime to fine powder in a special mill. This material is known as ground lime, which is good, but objectionable to handle. What is known as ground carbonate is limestone ground into a fine powder, so that it can be applied to the land by means of an ordinary fertilizer drill.
This is in most cases the best form to use if it can be obtained cheaply in a fine powder.