636. Where several properties liable on the same mortgage.

Where several properties of the same mortgagor which have been charged with a single debt become severed in title, they must, as between themselves, bear the mortgage debt rateably in proportion to their respective values1 unless, by special agreement in the mortgage itself or by declaration on the mortgagor's part, one property has been made liable to bear the whole debt in exoneration of the others2. The rule does not apply where one property is subject to a specific charge and the other to a general lien for the debt