22.4 L/mol (call it 20). Air is 80% N2, so let's just assume density of air is 30g/mol (N2 is 28, round up for ease of use.) Helium, I think, is monoatomic, so

22.4 L/mol (call it 20). Air is 80% N2, so let's just assume density of air is 30g/mol (N2 is 28, round up for ease of use.) Helium, I think, is monoatomic, so 2g/mol. Thus, load supportability is 28g for every 22.4L. 35lb(454g/lb)(22.4L/28g) = a lot, maybe around 10,000L.