2 was subjected to digestive ripening for 1 5 h after cooling down to room temperature 10 ml of the digested colloid containing 0 025 g au was precipitated with 50 ml of absolute ethanol after overnight treatment the precipitation was complete and the supernatant was carefully removed by sucking out with a pasteur pipette the remaining precipitate together with a small amount of leftover toluene thiol and ethanol was dried under vacuum until constant pressure 5 u00d7 10 u2212 3 torr after drying the color of the product was brown red and it had the appearance of a wet paste an additional 3 ml of ethanol was added and the system was left undisturbed overnight the supernatant was then removed and the sediment again was dried under vacuum at constant pressure after drying the precipitate 0 0214 g was a powder with small shiny dark crystals it was washed again with 3 ml of ethanol left overnight the supernatant removed and dried under vacuum after drying the precipitate was 0 0207 g and no change of the mass was recorded after additional washing with ethanol and drying under vacuum the yield was 84 based on gold if the adsorbed thiol is taken into account the yield was u02dc 73 the final dry product was in the form of soft shiny dark crystals which are readily soluble in toluene or hexane after addition of the solvent the crystals immediately dissolved giving wine red colored colloidal solution however the.