(a) When compensation is awarded because of disability or death caused by silicosis, anthraco-silicosis, coal worker's pneumoconiosis, asbestosis, or any other occupational disease which developed to the point of disablement only after an exposure of five or more years, the compensation for disability or death due to such disease shall, except as otherwise provided in subsection (g) of section 301,¹ be paid jointly by the employer and the Commonwealth and the employer shall be liable for sixty per centum of the compensation due and the Commonwealth forty per centum.

(b) Compensation payable by the Commonwealth under subsection (a) of this section shall be paid out of appropriations made from time to time to the department out of the General Fund in the State Treasury.

(c) In all claims for compensation partially payable by the Commonwealth under subsection (a) of this section, the department shall be designated as a codefendant.

(d) In all agreements for the payment of compensation and all awards, the amount payable by the employer and the amount payable by the Commonwealth shall be separately stated. An award against the employer shall be for only the percentage of the total compensation which the employer is obligated to pay under subsection (a) of this section, not to exceed the stated percentage of the maximum payable by the employer under section 301 (a) 2 of this act, or if section 301 (a) 2 be inapplicable, then under sections 306 and 307 of this act.² A separate award shall be made against the Commonwealth for the balance of the compensation payable under said sections, which shall be payable out of appropriations made as aforesaid. Nothing in this section shall prohibit the Commonwealth from entering into agreements to pay the compensation for which it is liable: Provided, however, That where compensation is payable under the provisions of subsection (a) of this section, the Commonwealth shall not enter into an agreement unless the employer is a party to the agreement: And provided further, That any such agreement shall contain facts sufficient to entitle the claimant to compensation and shall be accompanied by a supporting medical certificate. All such agreements shall be approved by the board or by a referee.