an early theory in organic chemistry. According to the etherin theory, ethylene (which was named etherin by J. Berzelius because of its weak ethereal odor) was a group of atoms that entered ethyl alcohol and several other organic compounds without change, just as ammonia becomes a component of ammonium salts.
The etherin theory was formulated in 1828 by the French chemists J. Dumas and P. Boullay, who based their conclusions on the experimental results obtained by J. Gay-Lussac in 1815 and on their own studies of the composition of ethylsulfuric acid and other esters of ethyl alcohol. Gay-Lussac’s experiments showed that the density of ethyl alcohol vapor is equal to the sum of the densities of equal volumes of ethylene and water vapor and that the density of ether vapor is equal to the sum of the densities of one volume of water vapor and two volumes of ethylene. The etherin theory was a forerunner of the radical theory.