surface roughness and the strong jump-up-to-contact by formation of capillary bridges due to adsorbed water [@Zwo08d]. It was found that even for the lowest attainable relative humidity $\sim2\% \pm 1\%$ large capillary forces are still present.

In this paper we use the term adsorption in sense of physisorption when the electronic structure of atoms or molecules is barely perturbed upon adsorption. Formation of capillary bridges takes place due to water adsorbed on $Au$. We can expect that the surface of $Au$ is covered with an ultra thin water layer, which is present on almost all surfaces exposed to air. Experiment [@Zwo08d] suggest that the thickness of this layer is in the nanometer range. The natural questions one could ask is how thick the water layer is, and what is the influence of this layers on the dispersive force? At short separations, $d\lesssim 20\;nm$, these questions become of crucial importance because they place doubts on our understanding of the dispersive forces when experiments under ambient conditions are compared with predictions of the Lifshitz theory. In this paper we are performing the first steps to answer these questions comparing experimental data at short separations with the theoretical predictions for $Au$ covered with 