This process, since it yields soap as one of its products, is called "saponification." All fats, when saponified, yield soaps and either glycerol or (more rarely) some of the other alcohols which are described below. Glycerine is also prepared from fats by hydrolysis with superheated steam. Using olein, a glyceride which is present in olive oil and many common fats, as the example in this case, the equation for the reaction is: C_{3}H_{5}(C_{17}H_{33}·COO)_{3} + 3H_{2}O = 3C_{17}H_{33}·COOH + Olein Steam Oleic acid C_{3}H_{5}(OH)_{3} Glycerol In this case the free fatty acid, instead of a soap, is the product which is obtained in addition to glycerol. In the equations presented above, a single glyceride has been used as the example in each case. In the saponification, or hydrolysis, of natural fats and oils which, as has been shown, are mixtures of many glycerides, the resultant soaps, or fatty acids, are mixtures of as many compounds as there were individual glycerides of the original fat, but the glycerol is identical in every case. When glycerol is heated with dehydrating agents, it is easily converted into _acrolein_, an unsaturated aldehyde having a peculiar characteristic pungent odor. Hence, the presence of glycerol, or glycerides, in any substance may usually be detected by mixing the material with anhydrous acid potassium sulfate and heating the mixture in a test tube, when the characteristic odor of acrolein will appear. Glycerol possesses all the characteristic properties of an alcohol, forming alcoholates with alkalies, esters with acids, etc. It is an active reducing agent, being itself easily oxidized to a variety of different products depending upon the strength of the oxidizing agent used and the conditions of the experiment. Microorganisms affect it in a variety of ways, either converting it into simple fatty acids, or condensing it into longer-chain compounds. =Open-chain monohydric alcohols=, higher members of the ethyl alcohol series, such as cetyl, C_{16}H_{33}OH, carnaubyl, C_{24}H_{49}OH, ceryl, C_{26}H_{53}OH, and melissyl, C_{30}H_{61}OH, are found in the esters which constitute the major proportion of the common waxes.