Section 6. The superintendent of the Tewksbury hospital may deposit in any bank or trust company within the commonwealth or on paid-up shares and accounts of and in co-operative banks, funds belonging to patients and funds deposited by their relatives or friends to be used for their benefit or may use said funds to purchase share accounts of a federal savings and loan association located in the commonwealth, in an account entitled ”Patients’ Funds”, or the superintendent may, whenever he deems it desirable, deposit such funds in such banks in separate accounts as trustee or use said funds to purchase share accounts of a federal savings and loan association located in the commonwealth, as trustee, in each instance, for the patient.