HYDROLYSIS, in chemistry, a decomposition brought about by water after the manner shown in the equation R-X+ H.OH=R•H+X•OH. Modern research tends to prove that such reactions are not occasioned by water acting as H20, but by its ions (hydrions and hydroxyl ions), for the velocity is proportional (in many cases) to the concentration of one or both of these ions. This fact explains the so-called "catalytic" action of acids and bases in decomposing such compounds as the esters. The term "saponification" (Lat. sago, soap) has the same meaning, but it is more properly restricted to the hydrolysis of the fats, i.e., glyc eryl esters of organic acids, into glycerin and a soap. (See