104 Ammonia. 
heavy rain in the doorway. The sport which this caused was 
thought to be well worth the wetting. Probably the magnificent 
gardens at Chatsworth are the only places where anything at all 
similar to the above is now to be found. There are some practi- 
cal wet jokes even here; and country bumpkins, in their native 
innocence, may be found willing to pay a visit to the weeping 
tree. This visit is never repeated." 
AMMONIA. 
BY DR. E. EMMONS. 
This compound of nitrogen and hydrogen is exceedingly im- 
portant in vegetation. Some of our most important grains require 
its presence. It exists in the atmosphere; and it is developed in 
the decay of animal and vegetable substances, from which it es- 
capes into the atmosphere, ready to enter into new combination. 
One single property of this substance fits it to play its important 
part in the vegetable economy, namely, its ready absorption by 
porous bodies. This property is manifested and proved in innu- 
merable instances, some of which fall under observation in our 
ordinary manual operations; for example, plaster, when placed 
in a stable, or in any place where organic matters are undergoing 
decomposition, takes up the ammonia as it escapes; lime also 
performs a similar office. A direct experiment, which proves 
this statement, is often performed in the labratory ; thus, we have 
only to pass a little plaster, lime, charcoal, earth, ect., into a re- 
ceiver containing ammonia, over mercury, when the whole of the 
ammonia disappears: it is absorbed and condensed in the pores of 
the body employed. Any moist substance whatever produces 
this effect instantaneously, so powerful is the affinity of ammonia 
for water. The same process goes on in nature: the ammonia 
floating in the atmosphere is continually absorbed by soil, by 
humus, and especially by clay; and all these substances give cut 
their ammonia on the application of sufficient heat to dissippate 
