Memoir on Human Uririé. 49 
phofphat, which depofits itfelf in cryftals. The uric acid is 
equally faturated, and prefents urate of ammonia; which 
fometimes depofits itfelf in the calculous matter with the 
triple phofphat jult mentioned. This triple phofphat fepa- 
rates itfelf in cryftals of the liquor only becaufe it is lefs fo- 
luble than the two infulated phofphats. This falt, therefore, 
which does not exift quite formed in the urine, is the pro- 
-duce of its ammoniacal alteration. 
As ammonia and the carbonic acid go on always in- 
creafing when the uri¢ and phofphoric acids and the phof- 
phat of magnhefia are faturated, there remains in the liquor 
carbonate of ammonia, which then renders fyrup of violets 
green, and effervefces with acids. The acetous acid, which 
is formed at the fame time, becomes faturated alfo with am- 
monia; fo that the urine contains, at the fame time, acetite 
and carbonate of ammonia. Thefe three fubitances, formed 
almoft at the fame time by the decompofition of the urine; 
ammonia, the phofphoric and the acetous acids, are the 
produce of the urinary matter, which ceafes to be found in 
that liquid when altered by putrefaction. 
X. This alteration of urine does not always take place in 
the fame manner, and its decompofition varies according to 
the diverfified nature of that liquor. Sometimes, in one in- 
dividual, avhen the urine commonly prefents the before- 
mentioned phenomena, the liquid, inftead of emitting an 
ammoniacal odour, becomes covered with a green and white 
mouldinefs, which increafes for fifteen or twenty days. In- 
ftead of containing ammonia naked, it contains the acid, and 
emits a fmell of it. This kind of urine is lefs fubjeét to al- 
teration than the preceding. It appears to be at leaft as 
common as that which alcalifes. Their difference depends 
evidently on the variation of their principles, and not on theit 
nature; for they are almoft always the fame, except in their 
proportion. Thus the urinary matter, the fource of the 
formation of ammonia, of the carbonic and acetous acids, 
and the caufe of the alterability of urine, does not produce 
or experience that alteration, or that decompofition, but fo 
far as it is mixed with a certain quantity of gelatinous mat- 
ter, which ferves it as a ferment. If it does not contain 
Vou. V, hi enough, 
