|Poor Wandering One|
This is a great find. Based on this discovery:
Concentrate poison: ...
It appears poisons cannot be concentrated into a single "dose". So, if he has this discovery then he can combine doses into one stronger poison, which lasts 1 hour. If he doesn't have the discovery, he can't combine multiple doses into a single container. He would have to apply each dose of poison individually.
Thank you for mentioning this. The alchemist is breaking the rules, though he may not realize it.
Mind you inhaled poisons have an odd exception here. Multiple doses can stack once delivered/dispersed into an area. The trick is delivery, which PF limits to traps and Poison Sand Tubes.
Even the modern gas grenades are listed as only being able to be loaded w/ mustard gas.