365 A.2d 905 Penzoil United, Inc. and Aetna Casualty Surety Company, Appellants v. Fred J. Mitchell and Workmen’s Compensation Appeal Board, Appellees. Commonwealth Court of Pennsylvania.Argued September 13, 1976 November 16, 1976. Workmen’s compensation — Scope of appellate review — Violation of constitutional rights — Error of law — Findings of fact — Substantial evidence […]