This may acctually be hard coded (read unchangable,) not sure.
I added the 1 minute (10 rounds option.)
Alchemist fire adds 1d4 fire dmg to a melee weapon (or 1d4+1 cant remember.)
Its something that can be usefull for low level characters, and its something that low level characters can acctually make, if they want to produce some to prepare for some battles.
Higher level characters aren't really going to use it since the amount of work is > the relative benefit at their level even if its increased in duration to 1 turn (10 rounds.)
10 rounds is still short, but long enough to last through a battle or two.
-TV