85 



AMMONIA. 



This substance is known also by the name of the 

 volatile alkali. It is composed of nitrogen and 

 hydrogen. In its purest form it is in the gaseous 

 state. It is then called ammoniacal gas. 



Ammoniacal gas is procured by adding dry 

 quicklime to muriate of ammonia, and exposing 

 them in a retort to the heat of a lamp. The mu- 

 riatic acid, having a stronger attraction for the lime 

 than it has for the ammonia, leaves the latter, which 

 is disengaged, in the state of gas. A pneumatic 

 apparatus is necessary for this purpose, as this gas 

 is rapidly absorbed by water. Ammoniacal gas 

 has a strong pungent smell, and suffocates animals 

 immersed in it. It changes vegetable blues to 

 green. If water be introduced into the apparatus, 

 in contact with the gas, it absorbs it entirely, and 

 acquires its peculiar smell : this is a solution of 

 ammonia in water, and is called liquid ammonia. 



Ammonia exists as a constituent in animal 

 bodies ; and it is obtained from bones, horns, &c. 



It is a valuable material in manufactiu'es and 

 medicine. Ammonia forms with the acids several 

 valuable compounds. 



With carbonic acid it forms carbonate and hi- 

 carbonate of ammonia. The carbonate may be 

 obtained by mixing ammoniacal gas with carbonic 

 acid gas over mercury. The two gases inunedi- 

 ately combine and form a solid white body, which 

 still retains some of the pungent smell of the am- 

 monia. This is the common smelBig salts. The 

 bi-carbonate is procured by causing a current of 

 carbonic acid gas to pass througli liquid ammonia. 

 It has no smell. 



G S 



