You can take more damage before being killed.
Prerequisites
Alchemist Level 4
Benefit
The alchemist is familiar enough with the ties between his body and spirit that he lingers at death’s door far longer than a normal person. He treats his Constitution as 10 points higher than normal for the purpose of determining when hit point damage kills him (so an alchemist with a Constitution of 10 and this discovery dies at –20 hit points instead of –10). Reducing him to 0 Constitution or its equivalent (from ability damage, ability drain, Constitution penalties, and so on) makes him unconscious and comatose, but he is only killed after taking an additional 5 points of Constitution damage, drain, or penalty (in effect, the alchemist must be brought to –5 Constitution in order to be killed by these attacks).