A flask of acid is not a small dose, its about a pint of acid.
Technically the rules for crafting (alchemy being a craft skill) says you produce an amount of finished product equal to the DC times the roll in silver pieces for a week worth of effort. That is right, one week, of working 8 hours a day. The rules do let you break that down into one day portions, you just divide the total of the skill roll time the DC by 7. So a vial of acid is 100sp value, figuring you roll a 10 with an average total skill of 12 is 22 times the DC 15, or 330sp. Meaning it would take at least 2 days to make 1 vial. You can increase the difficulty to decrease the time a bit.
The point I am trying to make is crafting in Pathfinder is not mass production. Without magical assistance it takes quite a bit of time to make items.
I think your expectations of taking raw materials and almost instant titrating them into a high molarity acid with a cauldron is more then a little unrealistic. But if you really want to be able to make alchemical substances quickly, play an alchemist. They get the fast, and, eventually, instant alchemy abilities.
