A PRIZE ESSAY. 
39 
practice it is found the effects of urine are nearly 
double those of dung. Look now for the reason of 
this. In the first place, the principle which gives am¬ 
monia in urine runs at once by putrefaction into that 
state. It gives nothing else; whereas in dung the 
ammonia arises from a slower decay, and the principle 
which here affords ammonia may, and without doubt 
does, form other products. Hence, we have a quick 
action with the liquid, a slower one with the solid. 
A second cause of the better effects of the liquid is, 
that it contains, besides its ammonia, a far greater 
amount of salts, and these give a more permanent 
effect. The amount of salts in human, cow, and horse 
dung is about one pound in every hundred; while 
the urine of the same animals contains nearly six 
pounds in every hundred. A third cause of the 
greater fertilizing action is found in the peculiar char¬ 
acter of some of these salts, which are composed of 
soda, potash, lime, &c., united to an acid formed from 
urea, in the animal body. This acid is like, the acid 
of saltpetre ; it is a nourisher of plants, as much so as 
is carbonic acid. 
SECTION IX. 
OF THE CAUSES WHICH MAKE URINE BETTER OR WORSE, MORE 
OR LESS, AND THE MODES OF PRESERVING- IT. 
There can be no doubt that the same causes which 
we have pointed out as affecting the value of dung, 
affect also the urine. 
We have already alluded (p. 38) to the four chief 
circumstances to be regarded in urine. And first, of 
its composition. It will be affected by the age, sex, 
food, and difference of animal. The process of form 
