19. Effect of payment on account of debt or of interest on legacy. Where payment on account of a debt or of interest on a legacy is made before the expiration of the prescribed period by the person liable to pay the debt or legacy or by his agent duly authori-
sed in this behalf, a fresh period of limitation shall be computed from the time when the payment was made: Provided that, save in the case of payment of interest made before the 1st day of January, 1928 , an acknowledgment of the payment appears in the handwriting of, or in a writing signed by, the person making the payment. Explanation.- For the purposes of this section,-
(a) where mortgaged land is in the possession of the mortgagee, the receipt of the rent or produce of such land shall be deemed to be a payment;
(b) " debt" does not include money payable under a decree or order of a court.