The literature on the hydrogenation of compounds with systems of conjugated double bonds is reviewed in connection with the hydrogenation of Chinese wood oil. However, further experiments showed, that the hydrogenation of this oil is a more complicated reaction than was previously assumed, for, besides addition of hydrogen, shifting of the double bonds also takes place. From the hydrogenation results and observations made on other and similar reactions, an attempt was made to explain, why this migration of the double bonds occurs in this way. Obviously the system of conjugated double bonds in elaeostearic acid does not invest a stable position and therefore tries to take a more stable one during the reaction.