... in which we learn about refrigeration and the compounds that made this possible (CFCs), the ozone layer, chemical warfare, PCBs, pesticides such as DDT, dioxin, chloroform, etc.
"The ideal refrigerant molecule has special practical requirements. It must vaporize within the right temperature range; it must liquefy by compression—again within the required temperature range; and it must absorb relatively large amounts of heat as it vaporizes. Ammonia, ether, methyl chloride, sulfur dioxide, and similar molecules satisfied these technical requirements as good refrigerants. But they either decomposed, were fire hazards, were poisonous, or smelled terrible—sometimes all of these.
Despite the problems with refrigerants, the demand for refrigeration, both commercial and domestic, grew. Commercial refrigeration, developed to meet the demand of trade, preceded home refrigeration by fifty or more years. The first refrigerators for in-home use became available in 1913 and by the 1920s had begun to replace the more traditional icebox, supplied with ice from industrial ice plants. In some early home refrigerators the noisy compressor unit was installed in the basement, separate from the food box.
Looking for an answer to concerns about toxic and explosive refrigerants, mechanical engineer Thomas Midgley, Jr.—already successful as the developer of tetraethyl lead, a substance added to gasoline to reduce engine knock—and chemist Albert Henne, working at the Frigidaire Division of General Motors, considered compounds that were likely to have boiling points within the defined range of a refrigeration cycle. Most of the known compounds that fitted this criterion were already in use or had been eliminated as impractical, but one possibility, compounds of fluorine, had not been considered. The element fluorine is a highly toxic and corrosive gas, and few organic compounds containing fluorine had ever been prepared.
Midgley and Henne decided to prepare a number of different molecules containing one or two carbon atoms and a varying number of fluorine and chlorine atoms instead of hydrogen atoms. The resulting compounds, chlorofluorocarbons (or CFCs, as they are now known), admirably fulfilled all the technical requirements of a refrigerant and were also very stable, nonflammable, nontoxic, inexpensive to manufacture, and nearly odorless."