Digestion converts any
nitrogen in the food (other than that which is in the form of nitrates or nitrites) into ammonia,
and other organic matter to C02 and H20. Ammonia gas is not liberated in an acid solution
because the ammonia is in the form of the ammonium ion (NH4
+
) which binds to the sulfate ion
(SO4
2-) and thus remains in solution: