Freon, a Refrigerant K. J. 'faowsoru, Kinetic Chemicals, Irtc., Wilmington, Del. wliidi still has propertics especially favora b l e to economic operation. Freon is adaptable for use in all compn:ssion types of refrigerating systems, and tests have s2ion.n that it closely approaches tlre ideal refrigerant. T 11 e p li y s i c a I , cliemical, and t h e r inodgnainic p r o per t i e s of Freon !lave liceii c a r e f u l l y and fully studied, and the v a l u e s h a v e been made available throogli the publicat i o n s l i s t e d a t the cud of t h i s p a p e r . These d a t a f u r n i s h
1i ways lieen an essential i n inany iiidustrics, and particularly in tile ciiemiaa.1 industry. Icewasthe first and only refrigeration medium f o r many centuries, but there were so many disadvantages conIiected with its u s ~ that other incans wore s o u g h t , and it iviyiis fiiiind that a nuiiiliiir OS liquids aiid giyiisea could be used to produce r e f r i g e r a t i o n . There are two principal m e t h o d s b y which they are employed: one, genera l l y r e f e r r e d to as the indirect niet.hod. is the circulation of cooled solutiuna; the otlwr, the direct method, is the circulation and expansion of the refrigeralit itself. Refrigerat.ion, either by the direct or indirect method, was k s t employed almost entirely in industrial applications, hut was aft,erward extended to take the place of ice in coiiimercial uses as well, and more recently has been adapt,ed to household refrigerating equipment. Unfortunately there were certain itrliereiit hazards in the use of the refrigerants employed; and, while the liazards could be fairly well controlled in industria1 refrigeration because suitable precautions could be enforced, their control was not practicable in commercial and liousehold refrigerating systems. The chief lrasards mere those of fires and explosions of tlre rcfrirrertantsthemselves, liealtli hazards duo to the lxieitv of the i & p r a n t s , the hazards due to clicrniw~lreuctioik resulting from the accidental introductiorr of the refrigerant Sroni the cooling system into tlrc d, and in some casrs tlie haeards ..
iiiformation that is neceasar~- to intelligently design and operate tiis plant; hoverer, a fen- outstanding properties will he discussod briefly. Cr
