crith

crith [Gk: ‘barleycorn’] mass The mass of 1 litre of hydrogen at s.t.p., = 90.6∼ mg (1.40∼ gr). Since the mass of any gas is proportional to its relative molecular mass, which for hydrogen gas is virtually 2, the mass in crith of 1 litre of any gas under standard conditions is essentially half its relative molecular mass (‘molecular weight’).