Ancient Greek temple three steps, the "crepidoma". The uppermost level of the "crepidoma" provides the surface on which the columns and walls are placed; it is called stylobate. Placed on the stylobate are the vertical column shafts, tapering towards the top. They are normally made of several separately cut column drums. Depending on the architectural order, a different number of flutings are cut into the column shaft: Doric columns have 18 to 20 flutings, Ionic and Corinthian ones normally have 24. Early Ionic columns had up to 48 flutings. While Doric columns stand directly on the stylobate, Ionic and Corinthian ones possess a
Ionic compound usually in a crystalline structure. Ionic compounds containing hydrogen ions (H) are classified as acids, and those containing basic ions hydroxide (OH) or oxide (O) are classified as bases. Ionic compounds without these ions are also known as salts and can be formed by acid–base reactions. Ionic compounds can also be produced from their constituent ions by evaporation of their solvent, precipitation, freezing, a solid-state reaction, or the electron transfer reaction of reactive metals with reactive non-metals, such as halogen gases. Ionic compounds typically have high melting and boiling points, and are hard and brittle. As solids they are almost