Original oil and gas trade magazine vintage ad for UNIVERSAL OIL PRODUCTS COMPANY of Chicago, IL. Dubbs Cracking Process. Dan Corcoran of the Black Gold Refining Company. Dubbscracking is the way to survive the Economic Storm. Turns a barrel of crude into high grade oils. This unique 1934 old petroleum products refining industry magazine advertisement would look fabulous matted and framed. Approximate size 10 x 13 inches.