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 and negative ions must be maintained. Instead the material undergoes fracture via cleavage. As the temperature is elevated (usually close to the melting point) a ductile–brittle transition occurs, and plastic flow becomes possible by the motion of dislocations. The compressibility of an ionic compound is strongly determined by its structure, and in particular the coordination number. For example, halides with the caesium chloride structure (coordination number 8) are less compressible than those with the sodium chloride structure (coordination number 6), and less again than those with a coordination number of 4. When ionic compounds dissolve, the individual ions dissociate and