Lime 



In many places it is sufficient only to apply lime 

 to the soil to get a crop of wheat where formerly 

 such a thing was impossible. 



Lime (CaO). 



Lime comes from the calcination of limestone, 

 which is more or less pure calcaire (CaCos). By 

 calcination the carbonic anhydride [CO2], commonly 

 called carbonic acid, is expelled, and what remains 

 (CaO) is quicklime. So many lime kilns are still 

 used in England that it is unnecessary to describe 

 their working. Limestone is found in many parts of 

 England. It is easily recognised, because under an 

 acid (vinegar) it effervesces. This test is particularly 

 striking if chlorhydric acid is used. The purest 

 limestone is obviously the best, because it will give 

 the most lime. Lime is white when the limestone 

 is pure. In this case it swells considerably with 

 water, and the best lime gives 95-97 per cent, of 

 lime. Less pure limestone, containing clay, is not 

 good. The lime derived from it has the property 

 of hardening under water, and gives hydraulic lime, 

 which is not suitable for agricultural purposes. It 

 contains 70 per cent, of lime. Siliceous lime is 

 poor, only swelling slightly, and of a grey colour. 

 It contains more than 70 per cent, of lime. Lime 

 obtained from calcareous dolomites is brown or 

 yellow. It is very efficacious, but perhaps more or 

 less injurious according to the quantity of magnesia 

 it contains. Lime having a greater affinity for the 

 carbonic anhydride and other acids, the magnesia 

 may retain its caustic properties for a long time, or 

 else its caustic action on plant life is more harmful. 



129 K 



