*11-1 Metals A and B form a terminal solid solution , cubic in structure. The var1ation of the lattice parameter of with composition, determined by quenching single-phase alloys from an elevated temperature, is found to be linear, the parameter varying from 3.6060A for pure A to 3.6140A in containing 4.0 weight percent B. The solvus curve is to be determined by quenching a two-phase alloy containing 5.0 weight percent B from a series of temperatures and measuring the parameter of the contained . How precisely must the parameter be measured if the solvus curve is to be located within \pm 0.1 weight percent B at any temperature