Section 320. Certain deeds deemed mortgages

A deed conveying real property,
  which, by any other written instrument, appears to be intended only as a
  security in the nature of a mortgage, although an absolute conveyance in
  terms,  must  be considered a mortgage; and the person for whose benefit
  such deed is made, derives no  advantage  from  the  recording  thereof,
  unless  every  writing,  operating  as  a  defeasance  of  the  same, or
  explanatory of its being desired to have the effect only of a  mortgage,
  or conditional deed, is also recorded therewith, and at the same time.