FATS AND OILS, WAXES, AND LIPOIDS 135 



oil and many common fats, as the example in this case, the equa- 

 tion for the reaction is: 



C 3 H 5 (Ci 7 H 33 C00) 3 +3H 2 = 3Ci 7 H 33 COOH+C 3 H 5 (OH) 3 



Olein Steam Oleic acid 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 hydroly- 

 sis, of natural fats and oils which, as has been shown, are mixtures 

 of many glycerides, the resultant soaps, or fatty acids, are mix- 

 tures 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 alco- 

 hol, 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, CieHssOH, carnaubyl, C24H4gOH, 

 ceryl, C2eH5 3 OH, and melissyl, CsoHeiOH, are found in the esters 

 which constitute the major proportion of the common waxes. 



Cholesterol and phytosterol are empirical names for certain 

 closed-ring, monohydric alcohols which are found in relatively 

 small amounts in all fats, the former term designating those found 

 in animal fats and the latter those of plant origin. Their compo- 

 sition has not yet been definitely established. They are known 

 to contain two, or three, closed rings, probably of the phenan- 

 threne type; to form dichlor- and dibrom- addition products, 

 showing that they contain one side-chain double linkage; and 

 to yield ketones when oxidized, indicating that they are secondary 



