ABSTRACT
This chapter discusses that the force-distance curves for the n-butylammonium vermiculite gels on the D16 long-wavelength neutron diffractometer at the Institut Laue-Langevin (ILL), Grenoble, using the uniaxial pressure cell apparatus. The force-distance curves across the salt concentration ranges between 0.001 and 0.2 M. Various experiments are carried out over a narrower range of salt concentrations which are less useful, and those carried out at just once have salt concentration more or less useless. The use of cgs (centimeter, gram, second) units in this chapter facilitates comparison with the predictions of DLVO (Derjaguin-Landau-Verwey-Overbeek) theory. The concentration of the potential-determining ions by two decades in the external solution does not lead to any significant change in the surface potential expected from classical chemistry. The colloidal surface is treated as a two-phase system of an electrode (solid) and an electrolyte solution (liquid) rather than as a single inhomogeneous (gel) phase.
