I N T R O D U C T I O N T O V O L U M E 1 6 l x x v i i VII. Refrigerators and Patents Einstein and Leo Szilard’s collaboration on technical appliances, beginning in the fall of 1926, reached its peak during the period covered by the present volume. This manifests itself not only in the variety of inventions and the numerous patent appli- cations in foreign countries, but also in the increasingly more demanding task of administrative and technical management of these inventions and applications. Szilard played the role of the prime mover in all these endeavors. After having begun work on refrigerators in the laboratory of the Technical University of Berlin, Szilard started to look for companies that would buy their inventions, ensure space for construction and testing of the model refrigerators, cover their expenses and, finally, produce them for the market. In the two and a half years between the fall of 1926 and spring of 1929, Szilard and Einstein approached and established cooperation agreements with one Swedish and three German companies. In the extant patent descriptions there are no explicit indications as to which part of an invention can be attributed exclusively to Einstein. In the first patent on what would later be called the “Einstein-Szilard refrigerator” (Doc. 84), claims 2 and 3 describe the option of not sending the electric current through the liquid metal by means of electrodes, but to induce it by a changing outer magnetic field. Albert Korodi-Kornfeld, one of the engineers collaborating on this version, remembered this particular aspect as being Einstein’s idea. He also attributed to Einstein the in- vention of a “people’s fridge.” This model was the only cooler by Einstein and Szilard to be exhibited at a technical fair in the fall of 1928, and to have reached mass production (Abs. 65). Finally, in a short note, Einstein complained of Szilard’s lack of interest in the capillary pump for refrigerators (Doc. 264). Such a complaint would most likely make no sense if the pump were exclusively Szilard’s idea (see also Vol. 15, Intro- duction, p. lxxxix). In the patent description of a variant of the electrodynamic pump (Abs. 338), mention is made of its possible use for pressing molten metals in molds, a reference to an earlier patent by Szilard.