About 1500 cm3 of the diluted solution kept from the digestion experiments of sample S32, and those of S3, S13 and S16 combined were measured into 2-L beakers placed on the magnetic stirrer/hot plates. The solution was heated for evaporation to about one-third of the original volume and then seeded with ground commercially available alum crystals. The solutions were kept simmering at about 65 °C for further evaporation whilst it was agitated slowly for the crystals to be formed. When enough crystals were formed, the pulps were immediately filtered (hot). The filter cakes were re-dissolved in distilled water, evaporated to supersaturation and seeded to obtain new crystals. The crystals were again filtered. An amount of ethyl alcohol was poured on the filter cakes under suction to remove any entrapped solution. The crystals were dried in the oven for 24 h at 60 °C and samples taken for assay.