(a) Each of the commissioners, for the purposes mentioned in this act, shall have power to administer oaths, certify to official acts, issue subpoenas, compel the attendance of witnesses and the production of papers, way bills, books, accounts, documents and testimony. In case of disobedience on the part of any person or persons, or willful failure to comply with any order of the commission or any commissioner or any subpoena, or upon the refusal of any witness to testify regarding any matter upon which he may be lawfully interrogated, or to produce any books or papers in his custody or control which he shall have been required by any commissioner to produce, it shall be the duty of the circuit court or any court, or a judge thereof, upon application of a commissioner, to compel obedience by attachment proceedings for contempt, as in the case of disobedience of the requirements of a subpoena issued from such court, or a refusal to testify therein, and in addition said commissioner shall have the powers vested in justices of the peace and notaries public to compel witnesses to testify and to produce books and papers;

  (b) Each witness who shall appear before the commission by its order shall receive for his attendance the fees and mileage now provided for witnesses in civil cases in circuit court, which shall be audited and paid by the state in the same manner as other expenses are audited and paid, upon the presentation of proper vouchers sworn to by such witnesses and approved by the chairman of the commission: Provided, That no witnesses subpoenaed at the instance of parties other than the commission shall be entitled to compensation from the state for attendance and travel, unless the commission shall certify that his testimony was material and necessary to the matter investigated;

  (c) The commission or any party may, in any investigation, cause the depositions of witnesses residing within or without the state to be taken in the manner prescribed by law for like depositions in civil actions in the circuit courts;

  (d) A full and complete record shall be kept of all proceedings had before the commission on any investigation had under section 22 of this act and all testimony shall be taken down by a stenographer appointed by the commission. When any complaint is served upon the commission under the provisions of section 26 of this act the commission shall, before said action is reached for trial, cause the certified transcript of all proceedings had and testimony taken upon such investigation to be filed with the clerk of the circuit court of the county where the action is pending. A transcribed copy of the evidence and proceedings, or any specific part thereof, or any investigation, taken by the stenographer, certified by him to be a true and correct transcript of all the testimony on the investigation or of a particular witness, or of any specific part thereof, carefully compared by him with his original notes, and to be a correct statement of the evidence and proceedings had on such investigation so purporting to be taken and transcribed shall be received in evidence with the same effect as if such stenographer were present and testified to the facts so certified. A copy of such transcript shall be furnished upon demand, free of cost, to any party to such investigations, and to all other persons on payment of a reasonable amount therefor.