Despite the wide practical interest in particulate colloids there have been few studies that exploit the advantages of reflection and neutron scattering to study adsorption of particles at interfaces. Pickering emulsions that are stabilised by particles rather than molecular surfactants are attracting increased interest in applications that include drug delivery and industrial products. There are specific reasons for study of these materials. First, the studies of heterocoagulation have suggested that adsorption saturates at a monolayer coverage of silica particles although different patterns of coverage were observed when the particle size was varied. Secondly there is an interesting analogy to the adsorption of surfactants at concentrations above the critical micelle concentration (cmc). However hese materials will change in size or aggregation number with concentration.