.Remove the filter and residue from the funnel, and place them back in the
vessel. Add 5 mL of conc. HCl, place the vessel back on the heating source, and heat at
95EC ± 5EC until the filter paper dissolves. Remove the vessel from the heating source and
wash the cover and sides with reagent water. Filter the residue and collect the filtrate in the
same 100-mL volumetric flask. Allow filtrate to cool, then dilute to volume.