These experiments were undertaken in order to determine how closely the hypothesis “that the electric resistance in a pure metal is directly as its absolute temperature” holds for various metals at two easily ascertained temperatures,—that of the air in the room, and the boiling point of water. The apparatus used was a Wheatstone's bridge; one coil of wire kept in a vessel of water at the temperature of the air in the room being put against another, which could be heated up to 100° C. The experiments showed that the rate of increase of resistance with temperature was different for hard and soft specimens of the same metal, being always less in the hard.