Treat

From IvaPedia

Syntax: treat <dead materia> <potion>

Using the treat skill a trained chemist can create Acid or Poison materia. These materia are created by treating a dead materia shard with a greater acid potion and a viper venom potion respectively. This difficult task may indeed destroy the shard. Either successful or unsuccessful the chemist will suffer, unable to attempt the task again for a number of hours of game time(minutes).