The Analysis Of Glasses Using Hf/Hci Mixture

This method is particularly designed for the rapid determination of alkalis, but also gives all other components except SiO2. The powdered glass sample is dissolved in HF/HCI and evaporated to dryness; this converts the alkali fluorides to chlorides. Attempts to dissolve the residue in hot dil. HCL give a turbid solution, but this does not interfere with the method. After adding a few drops of perhydrol the solution is evaporated nearly to dryness, a few drops of conc. NH4OH added and an equal volume of alcohol. All metals except the alkalis are then precipitated with Schaffgotch's reagent as carbonates. The alcoholic filtrate contains the alkalis as chlorides.