SALT AND LIME. 829 



be added to liquid manure for the purpose of fixing 

 ammonia, because by particular processes, and by em- 

 ploying very strong solutions, carbonate of ammonia 

 and common salt may be made mutually to decompose 

 each other; under all ordinary circumstances, how- 

 ever, the two salts have no action on each other, and 

 it is quite useless to add common salt to animal ma- 

 nures, as a fixer for ammonia. 



894. Salt is of course of no use as a manure on 

 land near the sea-coast, or exposed to winds loaded 

 with the salt of sea spray. On other land it is fre- 

 quently employed, either alone or mixed with earth 

 and lime ; when used in the latter manner, it is 

 common to make a compost, by mixing salt, earth, 

 and lime, some time before it is required, and allow- 

 ing the mixture to remain some time, sheltered from 

 the rain, the whole being occasionally turned: such 

 a mixture contains a portion of carbonate of soda. 



895. When solutions of chloride of calcium (241) 

 and carbonate of soda are mixed together, they are 

 both decomposed, chloride of sodium (common salt) 

 and carbonate of lime (chalk) being produced. From 

 this fact it is evident that, under ordinary circum- 

 stances, chalk and common salt cannot decompose 

 ea.ch other; nevertheless, when chalk or lime is mixed 

 with salt and moist ear'th, a considerable quantity of 

 carbonate of soda and muriate of lime are produced, 

 an effect wiiich does not take place if a mixture of 

 the two salts is thrown into a quantity of water. 



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