Section 65D. So much of any funds known as ''Patients' Funds'' as represents monies belonging to, or deposited for the benefit of, former patients of any such institution, which shall have remained unclaimed for more than seven years, shall be paid by the superintendent thereof to the state treasurer to be held subject to be paid to the person establishing a lawful right thereto, with interest at the rate of three per cent per annum from the time when it was so paid to the state treasurer to the time when it is paid by him to such person; provided, that so much of any monies so paid to the state treasurer as may be necessary to reimburse the institution for any sum due for the support of the person by whom or for whose benefit such money was originally deposited shall be credited to said trustees for that purpose. After six years from the date when any such monies were paid to the state treasurer the same or any balance thereof then remaining in his hands may be used as a part of the ordinary revenue of the commonwealth. Any person may, however, establish his claim after the expiration of the six years above mentioned, and any claim so established shall be paid from the ordinary revenue of the commonwealth. Any person claiming a right to money deposited with the state treasurer under this section may establish the same by a petition to the probate court; provided, that in cases where claims amount to less than fifty dollars, the claims may be presented to the comptroller, who shall examine the same and allow and certify for payment such as may be proved to his satisfaction.