The Hiisi Alchemist (in-game Alkemisti) is an uncommon enemy that drops a high amount of gold. It throws random types of Potions, that will sometimes hurt itself.
Hiisi Alchemists can be used to gain potions that you cannot make on your own, such as the Lava potion. A somewhat reliable way to collect their thrown potions is to have them throw the potions at you while you (and/or they) are submerged in deep water or other liquid, as sufficient amounts of liquid will slow the potions down enough to prevent them breaking.
They can also be useful in helping you obtain potions useful in Alchemy.
The Hiisi Alchemist can throw potions containing anything in the Aggressive material list.
Potions thrown by Alchemists contain double the amount of liquid of a regular bottle, though if emptied the bottle cannot be refilled back up to 200% again and will only fill to 100%.