For example, sulphur is stable in the rhombic form till 95.4°, from then upwards it tends to change over into the prismatic form.
The phenomenon absolutely corresponds to that of fusion and solidification, only that it generally takes place less quickly; consequently we may have prismatic sulphur at ordinary temperature for some time, as well as rhombic sulphur at loo°.
This may be expressed in the chosen case by a symbol: "rhombic sulphur 9 ?
It crystallizes in the cubical system, often in beautiful octahedra and rhombic dodecahedra.
It crystallizes from water in colourless rhombic prisms, containing four molecules of water of crystallization, and possesses a very acid reaction.