A solvent used in the creation of Propane Hash Oil (or PHO), propane is often considered to produce higher quality concentrates than butane.
Merriam-Webster Online Dictionary
propane (noun)a heavy flammable gaseous alkane CH found in crude petroleum and natural gas and used especially as fuel and in chemical synthesis - 3 8
LPG, liquefied petroleum gas, C3H8, bottled gas, propane gas
