Specifies the determination of the total specific external and internal surface area of disperse or porous solids by measuring the amount of physically adsorbed gas according to the method of Brunauer, Emmett and Teller (BET method). The BET method is applicable only to adsorption isotherms of type II and type IV. The BET method cannot reliably be applied to type I isotherms or to solids which adsorb the measuring gas.
