42 ANIMA.L CHEMISTRY LECTURE II. 



Acetic Ethylic Water Acetic ether 



C 2 H 4 2 + C 3 H 6 - H 2 = C 4 H 8 4 



Palmitic Cetylic Water Spermaceti 



C l6 H 3a O, + C I6 H 34 - H a O = C 3Z H 64 Z 



Next, we have myricin, which forms from 60 to 80 per cent, 

 of ordinary beeswax, and is composed of a residue of palmitic 

 acid united with a residue of another solid alcohol, the melyssic, 

 having the formula C 30 H6 2 0. Myricin is formed according to 

 the same typical equation as spermaceti and acetic ether, 

 namely, A + B H 2 O = X ; but the constituent palmitic acid, 

 instead of being combined with the alcohol of its own group, is 

 combined with the alcohol containing a double number of carbon 

 atoms. 



The three following bodies are selected as examples of the 

 true fats. The first of them, namely, palm it in, is an impor- 

 tant constituent of palm oil or butter, and also exists in human 

 and other soft fats to a considerable extent. They are all 

 three produced in accordance with the same typical equation, 

 3A + B 3H 2 = X, as shown below : 



Fatty acid Glycerin Water 



3C l6 H 3a O z + C 3 H 8 3 - 3H 2 = Palmitin 



3C I8 H 36 Z + C 3 H 8 3 - 3H Z = Stearin 



3C I8 H 34 Z + C 3 H 8 3 - sH a O = Olein 



You observe that stearic acid is a homologue of palmitic acid, 

 to which it stands next but one on the series; but oleic acid, 

 which differs in composition from stearic acid by a deficiency of 

 two hydrogen atoms, belongs to another set of compounds alto- 

 gether, namely, the secondary series of fatty acids. The simplest 

 known acid of this series is the acrolic, which is a member of the 

 propionic group, and, as you may perceive by referring to the 

 previous table of propionic compounds, bears to propionic acid 

 the same relation that oleic bears to stearic acid. 



