765 ILCS 5/35a

Whenever a deed shall recite, either in the body of the said deed or in the acknowledgment thereto, that said deed was sealed by the grantors therein, such recital shall be deemed to constitute an adoption by said grantors of any seal appearing on said instrument, including the seal of the notary public or other officer taking such acknowledgment, as their private seal, and shall constitute such instrument a sealed instrument.