OF AGRICULTURE. 231 



plants. It also occasions a larger produce of grain, 

 and this grain, as when ammonia is employed, is more 

 nutritious in its quality. [Professor Jackson. 



Ammonia ( Volatile Alkali}. Three combined parts 

 hydrogen and one combined part nitrogen form ammo- 

 nia. It is a gas, colorless, irrespirable, of a pungent, 

 caustic taste, lighter than air, and possesses strong 

 alkaline properties, neutralizing acids and changing 

 vegetable yellows to brown. Being a gas, it is called 

 volatile alkali, to distinguish it from those that are 

 fixed or solid. The great source of the ammonia of 

 commerce is the liquor of the gas-works. 



Ammonia is used medicinally in various ways. It 

 is administered internally as a powerful stimulant, 

 and applied externally as a counter-irritant. 



Ammonia is one of the most active ingredients of 

 manure. It is produced by the putrefaction of all 

 vegetable and animal substances containing nitrogen. 

 The urine of animals evolves it in large quantities. If 

 this be be collected in tanks, and sulphuric acid (oil 

 of vitriol) added, fixed sulphate of ammonia is formed 

 in the liquid, and all the ammonia is thus saved for 

 farm use. Sulphate of lime (plaster) and sulphate of 

 iron (green vitriol) also serve to fix ammonia. As 

 the decomposition goes on, which forms ammonia, 

 carbonic acid is also generated, which unites with the 

 former, forming the carbonate of ammonia; it exists 

 in this form in the atmosphere. 



The application of ammonia increases the luxuri- 

 ance of vegetation and hastens the maturity of crops, 

 It enters the roots of plants dissolved in water, and, 

 ^according to Liebig, is absorbed by leaves from the 

 air. * 



