This document discusses various chemical processes involving oils and fatty acids, including hydrolysis, saponification, hydrogenation, rancidity, and drying oils. Hydrolysis involves the breakdown of triglycerides into free fatty acids and glycerol. Saponification is the hydrolysis of triglycerides with an alkali to produce soaps. Rancidity refers to the deterioration of oils over time resulting in unpleasant tastes and textures. Drying oils such as linseed oil harden when exposed to air through polymerization reactions.