Each branch of the legislature shall have the power to issue their subpoena, as heretofore practiced, into any part of the commonwealth, and by attachment to compel the attendance of all persons summoned as witnesses, and in case any witness brought to the bar of either house shall refuse to be sworn or affirmed, or having been sworn or affirmed, shall refuse to render an answer to all legal questions duly propounded, the speaker of the house before which such refusal shall be made, shall have full power by the direction of the said house to issue to the sergeant-at-arms a warrant of commitment to the prison of Dauphin county, the inspectors and keepers thereof are hereby authorized and required to receive and confine such delinquent so committed until discharged in due course; and the expense of such imprisonment shall be paid out of any money in the state treasury not otherwise appropriated.