TABLE 68.-Angular values between faces of dextrose monohydrate crystals The rhombic or orthorhombic system is characterized by three rectangular axes, a, b, and c, all of unequal length. In this class belong levulose, a-anhydrous dextrose, sorbose, mannose, trehalose, and raffinose. (a) LEVULOSE Crystal system: Orthorhombic. Class 6: Rhombic bisphenoidal. Symmetry type: Digonal holoaxial, characterized by three rectangular digonal axes of symmetry. Habit: Prismatic. Ratio of axes: a:b:c=0.8007:1:0.9067 (Schuster) [16]. TABLE 70.-Angular values between faces of levulose crystals Double refraction: Positive and very small. a=1.555,8=1.555±,y=1.555. Axial plane for red: c {001} Axial plane for blue: b {010} The axial angle is very small and becomes zero at certain wave lengths and temperatures so that the crystal appears uniaxial. |