And be it futher enacted, That if any postmaster, or other f}:???;??;h??n;;;???;'i. person authorized by the Postmaster-General, to receive the postage of postage_ letters, shall fraudulently demand or receive any rate of pomage, or gratuity or reward, other than is provided by this act, for the postage of letters or packets; on conviction thereof he shall forfeit for every such offence, one hundr