MANURES. 147 



used alone, should always be applied as a top dressing 

 to be carried into the soil by rains. The tendency of 

 lime to settle is so great that, when cutting drains, 

 it may often be observed in a whitish streak on the 

 top of the subsoil. After heavy doses of lime have 

 been given to the soil, and have settled so as to have 

 apparently ceased from their action, they may be 

 brought up and mixed with the soil by deeper plowing. 

 Lime should never he mixed with animal manures., 

 unless in compost with muck or some other good 

 absorbent, as it causes the escape of their ammonia. 



PLASTER OF PAEIS. 



Plaster of Paris or Gypsum (sulphate of lime) 

 is composed of sulphuric acid and lime in combina- 

 ti yU. 



It is a constituent of many phmts. It also fur- 

 nishes them with sulphuric acid, and with the sulphur 

 of wdiich a small quantity is contained in seeds, etc. 



It is an excellent absorbent of ammonia, and is' 

 very useful to sprinkle in stables, poultry houses, 

 pig-styes, and privies, where it absorbs the escap- 

 ing gases, saving them for the use of plants, and 

 purifying the air — rendering stables, etc., more 

 healthy than when not so supplied. 



CHLORIDE OF LIME. 



Chloride of lime contains lime and chlorine. It 

 furnishes both of these constituents to plants, and is 



