Black American patentIn 1954, a patent for "Methods and Means of Defrosting a Cold Diffuser" was issued to its Black American inventor, F.M. Jones (No. 2,666,298). It gave a method to defrost using a heating medium when the surface of the diffuser has accumulated a layer of frost or ice which would otherwise reduce its heat transfer capacity. He used a compressor, condenser and evaporator which were interconnected in a manner such that the compressed refrigerant could also accomplish the defrosting of the evaporator in a defrosting cycle. He was a prolific inventor, whose first patent was for a "Ticket Dispensing Machine" in 1939 (No. 2,163,754), accumulating about 20 more patents relating to gas engines and refrigeration devices in 20 years.