"Gallon" means a liquid measure that is not corrected for temperature and that contains 231 cubic inches or the equivalent of 4 1/4 pounds of propane or 100 cubic feet of natural gas. The term includes "gross gallons".
N.H. Admin. Code § Saf-C 4202.09
#10025, eff 11-16-11 (from Saf-C 4202.05)