Exclusive jurisdiction over the lands so purchased is hereby ceded to the United States by the Commonwealth of Pennsylvania, and said lands shall be exempt from the payment of all taxes, State and local: Provided, That the Commonwealth of Pennsylvania shall retain a concurrent jurisdiction with the United States over the lands so acquired by the United States, for the purpose of serving all civil processes: And provided further, That such criminal processes as may issue under the authority of the Commonwealth, against any person or persons charged with crimes committed without the area so acquired, may be executed therein, in the same manner as though this cession had not been granted.