52 PHYSIOLOGICAL CHEMISTRY. 



Caprylic acid, HCsHisCX, as glyceride in butter and other fats. 



Pelargonic acid, HC 9 Hi 7 O 2 , in vegetable kingdom, but not as glyceride. 



Capric acid, HCioHi 9 O 2 , in butter and other fats as glyceride. 



Undecylic acid, HCiiH^Oz, not found as natural glyceride. 



Laurie acid, HCi 2 H 23 O2, as glycerol ester in several fats. 



Myristic acid, HCi4H 27 O 2 , in nutmeg butter and other fats as glyceride. 



Palmitic acid, HdeHsiOs, as glyceride in many fats. 



Margaric acid, HCi 7 H 33 O 2 , obtained as artificial glyceride. 



Stearic acid, HCisHssC^, as glyceride in many fats. 



Arachidic acid, HC 2 oH 3 9O 2 , as glyceride in peanut oil. 



Behenic acid, HC 22 H 43 O 2 , as glyceride in certain oils. 



A few other acids of this series are known in glycerol com- 

 binations but they are unimportant. 



NON-SATURATED ACIDS, CnH 2 _ 2 2 AND C n H 2n _ 4 2 . ' 



Not many of these acids occur as natural glycerides. 



Hypogseic acid, Ci 6 H 3 oO 2 , as glyceride in peanut oil. 

 Oleic acid, Ci 8 H34O 2 , as glyceride in many oils. 

 Linoleic acid, CisH 32 O 2 , as glyceride in drying oils. 

 Ricinoleic acid, CisH^Os, as glyceride in castor oil. 



A large number of these acids occur in the edible fats, 

 while some are found in products of little importance, or in 

 such as have technical uses only. The fats which are most 

 commonly used as foods are those consisting largely or wholly 

 of stearin, palmitin and olein. Butter fat, however, contains 

 relatively large amounts of other glycerides. 



Reactions of Fats. Certain general reactions are common 

 to practically all fats and will be explained here in detail. 



SAPONIFICATION. This term is applied to the change 

 which follows when fats are treated with alkali solutions, 

 usually with application of heat. The fats decompose more 

 or less readily and as products we have soaps and glycerol, 

 according to these equations : 



C 3 H 5 (C 1 3H 35 2 )3 + 3KOH = C 3 H 5 (OH) 3 + 3KC 18 H 3B O 2 

 2C 3 H B (C 1S H 33 2 ) 3 + 3PbO + 3H 2 = 2C 3 H 5 (OH) 3 + 3Pb(C 18 H 33 O 2 ) 2 



In the first case potassium stearate is formed and in the 

 second lead oleate, which is the important constituent of lead 



