REVIEWS. 
351 
to give to them fresh activity, and so render the exercise of 
their functions more rapid and energetic. 
Among these medicaments, some have a mode of action 
which spreads over the entire organism, while others act 
more particularly on certain organs, or certain organic appa- 
ratus. We represent the first under the name of general 
excitants , and the last under that of special excitants . 
Carbonate of ammonia ( concrete volatile alkali — sal volatile 
of England). 
A saline, solid, white substance, in larger or smaller layers, 
formed of a multitude of small crystals, disposed in feather- 
like concretions, having an alkaline, volatile, well-known 
odour, and of a piquant, urinous, caustic taste. 
This salt is soluble in three times its quantity of cold 
water, and when put into boiling water quickly becomes 
volatilised ; it changes and equally becomes volatilised when 
exposed freely to the air — hence the necessity of keeping it 
in well-stopped bottles. It turns to green the blue colour of 
the mallow and the violet. All acids in the liquid state 
decompose it with effervescence, and disengage carbonic 
acid; itself, it decomposes the metallic salts in solution in 
water, with the exception of those of soda and potash, and 
two or three others, having oxides for their base, of the first 
class. 
Carbonate of ammonia exists nowhere pure in nature, but 
becomes frequently produced during spontaneous decom- 
position, or by the burning of organic matters containing 
azote. 
To obtain the salt pure, we introduce into a receptacle of 
earthenware equal parts of hydrochlorate of ammonia and 
chalk, or carbonate of lime, and we put the vessel into a re- 
verberating furnace, we adapt to it a prolonged neck, and to 
this we fix a recipient tube ; and with clay unite the joints 
and permit them to dry ; then we gradually heat them. Now 
a double decomposition ensues, the formation of water and 
chloride of calcium which remains within the vessel, and of 
