Upon closer inspection, the curves appear to have up to three linear domains in the semi-logarithmic plot. This is best seen in the data for the mixture containing 1000 µmol g -1 of NaCl (Figure ). The slope in the first domain (approximately between 0 -50 J g -1 ) is the steepest, i.e., in this hydration phase, the relative stiffness increase with progressing hydration is large in the semi-logarithmic representation.