These conclusions relating to the eects of salt
and urea on the two dyes can also be drawn from
an examination of the relationship between the
change in molar extinction coecient (d) of both
the soluble aggregate and monomeric species with
dierent concentrations of additive.
(i) In¯uence of salt on molar extinction coe-
cient: If aw is molar extinction coecient of the
soluble aggregate in water, as molar extinction