FATS AND OILS, WAXES, AND LIPOIDS 133 



(2) Acetic acid, CHs-COOH, occurs free in vinegar. 



(3) Butyric acid, C 3 H 7 -COOH, in butter fat. 



(4) Capric acid, CoHio-COOH, in butter fat and cocoa- 



nut oil. 



(5) Myristic acid, CiaH^-COOH, in cocoanut oil and 



spermaceti. - 



(6) Palmitic acid, CisHsi-COOH, in palm oil and many 



fats. 



(7) Stearic acid, CirHss-COOH, in most fats and oils. 



Intervening members of this series, such as caprylic acid, 

 -COOH, and lauric acid, CnEbs-COOH, are also found in 

 smaller quantities in cocoanut and palm nut oils, in butter fat, 

 and in spermaceti; while higher members of the series, as arachidic 

 acid, CigHsg-COOH, and lignoceric acid, C23H47-COOH, are 

 found in peanut oil; and cerotic acid, C25Hsi -COOH, and melissic 

 acid, C2f)H59-COOH, in beeswax and carnauba wax. 

 Unsaturated Acids: 



(b) Oleic acid series general formula, C n H2-i-COOH. 



(1) Crotonic acid, GaHs-COOH, occurs in croton oil. 



(2) Oleic acid, CnHss-COOH, occurs in many fats and 



oils. 



(3) Brassic acid, C2iH4i -COOH, occurs in rape-seed oil. 



(4) Ricinoleic acid, CnH^OH-COOH, occurs in castor 



oil. 



(c) Linoleic acid series general formula, C n H2n-3-COOH. 



(1) Linoleic acid, CiyHsi-COOH, occurs in linseed and 

 other drying oils. 



(d) Linolenic acid series general formula, CH2n-5*COOH. 



(1) Linolenic acid, CiTEbo'COOH, occurs in many 

 drying oils. 



It will be observed that all of these acids contain a multiple 

 of two total carbon atoms. No acid containing an uneven number 

 of carbon atoms has been found in a natural fat. Furthermore, 

 the acids which occur most commonly in natural fats are those 

 which contain eighteen carbon atoms; in fact, more than 80 per 

 cent of the glycerides which compose all animal and vegetable 

 fats are those of the Cig acids. This fact, in addition to 'the one 

 that the sugars and starches all contain multiples of six carbon 



