6 CONTENTS. 



tion of element A compound An oxide A salt Chemical 

 affinity. 35, Cohesion. GASEOUS ELEMENTS. 35, Oxygen Its 

 properties, etc. One-fifth of the atmosphere Half of animals 

 and plants Source of, in plants Exhaled by plants. 37, Hy- 

 drogen Its properties -How existing in nature In plants and 

 animals Its weight What it forms How assimilated by 

 plants. 38, Carburetted Hydrogen Where found Marsh gas 

 Fire damp Present in soils. 39, SulpJiuretted Hydrogen How 

 formed Its properties In marshy places Hurtful to vegetation 

 Effects in soils. 41, Nitrogen Its properties Forms nitric 

 acid with oxygen Forms ammonia with hydrogen. 42, Plants 

 do not absorb it from atmosphere. 43, Experiments of Law r es 

 and others on rain water Conclusion therefrom. 44, Chlorine 

 Its properties Sources, etc. 45, ELEMENTS FOKMING ACIDS 

 Silicon Its appearance Forms silicic acid Silicates of pot- 

 ash, lime, and magnesia Their use. 45, Silica Crystallized 

 and amorphous Its properties. 46, Soluble silica How formed, 

 ^nd uses of. 47, Value of soluble silica Sources of it. 48, Car- 

 bon Its properties. 48, Carbonic Acid How formed. 49, Its 

 uses to plants Uses of humus or mould. 50, Phosphorus Its 

 properties, etc.-^Phosphoric Acid Its composition and proper- 

 ties 50, .Bone Phosphate of Lime Its composition, etcr 51, 

 Neutral PhospJiate of Lime Its composition, etc. 51, Super- 

 phosphate of Lime Its composition How formed. 52, Its ac- 

 tion in soils, and Ronna's report on its action. 57, Sulphur 

 Its properties, etc. 58, Sulphuric Acid Its composition and 

 uses Cheapest source to farmer. ELEMENTS FOKMING BASES. 

 58. Calcium Its properties, etc. 59, Oxide of Calcium, or quick 

 lime Its composition. 59, Carbonate of Lime Its composition, 

 etc. How made quick lime, etc. 59, Hydrate of Lime Its com- 

 position. 60, How lime should be slacked. Marls rich in carbo- 

 nate of lime Quick lime more valuable than carbonate. 61, Neu- 

 tralizes acids in soils Liberates ammonia. 62, Effect on iron 

 pyrites On silicates of soda and potash On salt Its physical 

 effects. 63, What soils need lime. 64, How and what quantity 

 should be applied. 65, Sulphate of Lime Its composition At- 

 tracts little moisture. 66, Its benefits due to sulphuric acid 

 Why but little required. 66, Magnesium Its properties. 67, 

 Magnesia Its composition Its action Cheap sources of Too 

 much hurtful. 68, Iron Forms two oxides Protoxide injuri- 



