The volume continues and completes the description of the physical properties of the beryllium metal (electrical, electronic, optical properties and, in addition, emission and impact phenomena). Moreover its electrochemical behavior is described in detail. The unique combination of properties pointed out in the previous Volume A 2, 1991, is continued in the properties described in this Volume A 3. Many of the characteristic properties are determined by the peculiar Be electronic structure and by the special shape of its Fermi surface. Numerous investigations are concerned with these topics and with the better understanding of bonding in the metal by cluster calculations. Optical properties are studied with respect to useful applications, e.g., as precision optical surfaces of Be (in spacecraft technology). Finally the description of the electrochemical behavior contains the fundamental processes for production of pure Be and metal refining.