Colloidal Silver: Carey Lea's Soluble Silver from Silver Nitrate

Carey Lea found in 1891 that silver nitrate reduced by ferrous sulphate in the presence of sodium citrate gives a silver that dissolves in water with a deep red colour. The 1907 US Dispensatory gives the recipe: the mixed iron and citrate solutions poured into 10 % silver nitrate, the precipitate washed by redissolving it in water and throwing it down again with absolute alcohol. Dried, it is a bluish-green mass of about 97 % silver. Salt solutions precipitate it, so use distilled water only. The picture: our diagram.