Pernicious Poison
You can add a toxic additive to an alchemical poison to make it splash poison on its target. A poison with this additive deals an amount of poison damage equal to the poison's level if the target succeeds at its initial saving throw against it. A target that critically succeeds at its saving throw against this poison still takes no damage.
Traits
Feats with the additive trait allow you to add special substances to alchemical consumables you create when you use Quick Alchemy to create a consumable (you can't use additives with quick vials). You can add only one additive to a single alchemical item, you can add an additive only once per round, and most additive abilities specify a subset of alchemical consumables you can add them to.
This indicates abilities from the alchemist class.