An equation that defines the resistance-temperature value of any pure metal that takes the form of RT = RO(1 + AT + BT2) for values between the ice point (0oC) and the freezing point of antimony (630. 7oC) and the form RT = RO[1 + AT + BT2 + C(T-100)T2] between the oxygen point (-183. 0oC) and the ice point (0oC)