Physical methods of metal deposition under ultra-high vacuum conditions are currently used to manufacture electrically conductive surfaces. In the case of silica glass, a supplementary oxide layer is usually required to avoid the uncontrolled growth of metal nanoparticles on the surface. Here, we present a simple chemical method which allows the formation of a high density of small gold nanoparticles forming a film on bare silica glass surface. The deposition of gold takes place at ambient pressure and in water followed by a thermal treatment that leads to the formation a gold film of 6 nm thickness according to atomic force microscopy experiments. This film consists of juxtaposed nanoparticles, which insures electrical conductivity under vacuum, as attested by the possibility of doing scanning electron microscopy imaging without carbon coating.