Equilibrium Relative Humidity of Some Sulphuric Acid Solutions
% Sulphuric acid and density (g/ml)	R.H. %	% Sulphuric acid and density (g/ml)	R.H. %
80%, 1.720	1.0	40%, 1.300	57.0
75%, 1.660	2.2	35%, 1.258	66.8
70%, 1.605	5.1	30%, 1.217	75.9
65%, 1.549	17.0	20%, 1.138	88.5
55%, 1.421	26.8	15%, 1.101	92.9
50%, 1.392	36.9	10%, 1.066	96.2
45%, 1.344	46.8	5%, 1.030	98.6
*From: R. E. Wilson, J Indust. Eng. CHem., 13, 326 (1921)
Taken from Pethig p.126