In any of the following cases, sales of real estate on reversion shall be presumed to constitute a contract of loan for the amount of the price, with a mortgage on the property sold, as security:\nFirst: When the buyer fails to enter into material possession of the thing sold.\nSecond: When the vendor pays to the buyer interest on the selling price, though such interest may be called rental or otherwise.\nThird: When a grossly inadequate sum appears in the contract, as the price of alienation.\nHistory —Civil Code, 1930, § 1410.
Puerto Rico Legal Code