= Citat =:
Mortar and Pestle
This is the only tool which is required to make a potion. The quality of the Mortar and Pestle directly affects the initial quality of the potion produced.
Alembic
This will reduce the strength and duration of any negative effects produced by a given combination of ingredients. If the ingredients you are mixing do not have any negative effects, you do not need to use an Alembic. (Note that Skooma Pipes actually function as Alembics, though they are so weak as to be not really worth using for the purpose.)
Retort
This will increase the strength and duration of all positive effects in the potion. If the potion has no positive effects, this will do nothing. (Of course, since there's no way to make a potion affect anyone but yourself in Morrowind, there is no reason to make such a potion, other than perhaps to sell for profit.)
Calcinator
This will increase the strength and duration of all effects, positive or negative.