The presiding officer and members of the senate, while sitting as a court of impeachment, and the managers elected by the house of representatives, shall receive the sum of six dollars each per day, and shall be reimbursed for mileage expense in going from and returning to their places of residence by the ordinary traveled routes; the secretary, sergeant at arms, and all subordinate officers, clerks, and reporters, shall receive such amount as shall be determined upon by a majority vote of the members of such court. The same fees shall be allowed to witnesses, to officers, and to other persons serving process or orders, as are allowed for like services in criminal cases, but no fees can be demanded in advance. The state treasurer shall, upon the presentation of certificates signed by the presiding officer and secretary of the senate, pay all of the foregoing compensations and the expenses of the senate incurred under the provisions of this chapter.