All findings of the commission and the determination of every matter by it shall be made in writing and placed upon its minutes. Proof thereof shall be made by a copy of the same duly certified by the secretary under the seal of the commission. Whenever any matter has been determined by the commission, in the course of any proceeding before it the fact of such determination, duly certified, shall be received in all courts and by every officer in civil cases as prima facie evidence that such determination was right and proper. The record of the proceedings of the commission shall be deemed a public record, and shall at all reasonable times be subject to the inspection of the public.