16. There shall be recoverable, in the proceedings in execution of every certificate filed under this Act- (a) interest on the public demand to which the certificate relates, at the rate at which interest may, by law, be chargeable on the public demand on the date of the signing of the certificate or at the rate of six and a quarter per centum per annum, whichever is higher, from the date of the signing of the certificate up to the date of realization, (b) such costs as are directed to be paid under section 45, and (c) all charges incurred in respect of- (i) the service of notice under section 7, and of warrants and other processes, and (ii) all other proceedings taken for realizing the demand.