A brief history
Surprising to many who thought refrigeration was a recent invention of the last century, artificial refrigeration's roots actually reach back to William Cullen at the University of Glasgon in 1748. Unfortunately, the potential benefits his great discovery offered were never realized in his lifetime.
It wasn't until 57 years later, in 1805, that Oliver Evans made the first actual refrigeration machine. But again the concept failed to catch on with industry and fell into obscurity for another 29 years when Jacob Perkins, an American inventor obtained the patent for the first refrigerating machine that used a vapor compression cycle in 1834.
In 1850 Edmond Carre presented a modification of Perkins design, the first absorption machine (using water and sulfuric acid) and the predecessor of today's refrigeration technology. Ferdinand Carre, Edmond's brother, continued working on improving the process and introduced the first ammonia/water refrigeration machine in 1859. Refrigerants:
Virtually all of those early refrigerants were flammable, toxic or both. Accidents and subsequent deaths were common. Thomas Midgley took on the task of finding a nonflammable refrigerant with good stability in 1926. He'd already established himself in the scientific community by finding tetraethyl lead improved the octane rating of gasoline.
With associates Henne and McNary, Midgley observed that the refrigerants then in use comprised relatively few chemical elements, and were clustered in an intersecting row and column of the periodic table of elements. The element at the intersection of that row and column was fluorine. Though fluorine is known to be toxic by itself, Midgley and his collaborators felt that compounds containing it could be both nontoxic and nonflammable. Within three days of starting, Midgley and his collaborators had identified and synthesized dichlorodifluoromethane.
The shorthand nomenclature later introduced to simplify identification of the organic fluorides is still used today as the numbering system for refrigerants. The number designations indicate the refrigerants chemical composition and structure. The refrigerant, synthesized dichlorodifluoromethane, identified by Midgley's team in 1926 is now known as R-12.
The first toxicity test was performed by exposing a guinea pig to the new compound. Surprisingly, the animal was completely initially unaffected, but died when the test was repeated with another sample. After years of testing and refinement the development of fluorocarbon refrigerants was announced in April 1930. To demonstrate the safety of the new compounds, at a meeting of the American Chemical Society, Midgley inhaled R-12 and blew out a candle with it.*
* While this demonstration was dramatic, it would be a clear violation of safe handling practices of today's refrigerants and potentially life threatening. Please see more about refrigerant safety.