K.S.A. 58-2309 shall be construed so as to apply to mortgages heretofore paid, but not discharged of record: Provided, That if the residence of the holder of such mortgage can be ascertained, no action shall be brought until demand is made in accordance with said section; but such demand need not be in writing, and will be excused if the residence of the holder of such mortgage cannot, with due diligence, be ascertained.

L. 1889, ch. 175, § 2; March 6; R.S. 1923, 67-310.