Sec. 2d. And be it enacted, That no person in this State, shall hereafter hire, employ, or harbor any free negro or mulatto who shall emigrate or settle in this state, after the first day of June next, or any free negro or mulatto who shall come into this state from any other state, district or territory, and continue in this state for the space of ten successive days as above, under the penalty of twenty dollars for every day after the expiration of four days, any such free negro or mulatto * * * shall be so employed, hired or harbored, and all fines accruing under this act, * * * one half thereof to be applied to the informer, and the other half to the use of the county; and if any negro or mulatto shall remove from this state and remain without the limits thereof for a space longer than thirty consecutive days, unless before leaving the state he deposits with the clerk of the county in which he resides, a written statement of his object in so doing, and his intention of returning again, or unless he shall have been detained by sickness or coercion, of which he shall bring a certificate, he shall be regarded as a resident of another state, and be subject, if he return, to the penalties imposed by the foregoing provisions upon free negroes and mulattoes of another state, migrating to this state: Provided that nothing contained in this act shall prevent any free negro or mulatto from visiting Liberia, and returning to the state whenever he may choose to do so.