After any such acquisition, the municipal officers of such county or township, authorized by law as aforesaid, shall, from year to year, at the time of their annual levy of taxes for county, township, or road purposes, certify to the Auditor General the rate of levy of such taxes for the ensuing fiscal year. Thereupon the Auditor General shall ascertain the amount of taxes which would have been collected upon the assessed valuation, certified as hereinbefore provided, at the rate of the levy so certified. Upon the ascertainment of such amount, the same shall be paid by the Commonwealth, from time to time, to the county or township entitled thereto from funds appropriated for such purposes.