Formaldehyde
. Formaldehyde, compound of carbon, hydrogen, and oxygen. Formaldehyde was discovered in 1867 by the German chemist August Wilhelm von Hofmann . It is the simplest of the aldehydes. At ordinary temperature it is a gas with a very pungent odor. It can be compressed into a liquid that boils at -21° C (-5.8° F). Formaldehyde is prepared industrially by heating dry air and methyl alcohol vapor in the presence of a catalyst, such as copper or silver. More direct processes, whereby formaldehyde is synthesized from carbon monoxide and hydrogen, have been developed. In one process, water gas is passed over a catalyst at a temperature between 200° and 300° C (392° and 572° F) under a pressure of 7757 torr (150 lb/sq in). Pure formaldehyde is very reactive and polymerizes easily. See Plastics ; Polymer . Formalin is a trade name for a solution containing 40 percent formaldehyde and 60 percent water or water and methyl alcohol; it is employed as a disinfectant, insecticide, fungicide, and deodor