For a considerable number of years the glutaconic acids and their derivatives have been the subject of much discussion and not a little controversy. The interest attaching to these substances lies in the fact that they exhibit geometrical isomerism together with tautomeric mobility which is associated with the three carbon system and activated by two terminal carboxyl groups. On the one hand Deist considered that all the properties of these compounds could be completely explained on the basis of a simple geometrical isomerism of the maleic acid – fumaric acid type, while on the other hand, Thorpe postulated a “normal” or symmetrical structure to account for the properties of certain derivatives of glutaconic acid, and he subsequently applied it to all the glutaconic compounds.