i.e., V1 = consumption of (PDADMAC) which is equivalent to the
unreacted (PESNa) (eq/ml), V2 = consumption of (PDADMAC)
equivalent to 10 ml (PESNa) (eq/ml), for the correction of the volume
which equivalent to the 1 g cotton sample, we multiply the
(V2 V1) by factor 5.