BUILDING OF LIVING MATTER 111 



atoms in all the available spaces of the 

 carbon affinities except those of the atom at 

 the end of the chain, where, instead, an oxygen 

 atom and an hydroxyl group are placed, 

 then the formula of a fatty acid is obtained 

 thus : — 



H H H H H 



I I I I I 

 H-C-C-C-C-C-C=0 

 I I I I I I 

 H H H H H OH 



It is the group represented on the right-hand 

 side, with one carbon, one oxygen and one 

 hydroxyl, which gives the acid properties. 

 This group is known as the carboxyl group, 

 and always confers acid properties throughout 

 the organic world. 



Here, then, we have an organic acid, 

 and if three such molecules, each losing the 

 H atom of its acidic group, unite with the 

 glycerine molecule, each replacing a HO group 

 in that body, which unites with the H atom to 

 form H — O — H then there arises a fat. It 

 has only to be remarked that the actual fatty 

 acids formed in nature, are usually three times 

 as large as this one, by the union of three six- 

 carbon chains, only one of which possesses the 

 acid group. The union may be visualized as 



