WAXES 111 



ments of the tissues enables us to use it with more judgment and less 

 empirically than heretofore. 



Cotton-seed Oil consists of a mixture of the glycerides of oleic and 

 linoleic and palmitic acids, while Olive Oil consists almost entirely 

 (89 per cent, to 98 per cent.) of the triglyceride of oleic acid. 



Linseed-oil is of very great importance in the industries on account 

 of its peculiar property of hardening when it dries in thin films exposed 

 to the air, forming a transparent waterproof surface and accelerating 

 the drying of other substances (pigments, etc.), with which it is mixed. 

 This process of hardening takes place at first slowly, and then more 

 rapidly, the products of oxidation which are formed accelerating the 

 further stages of the process. The oxidation of linseed-oil which 

 results in hardening is, in fact, an "autocatalytic," that is, a self- 

 accelerated reaction, producing its own catalyzers. These substances 

 are believed to be unstable peroxides which readily break down, liber- 

 ating oxygen or possibly ozone, which oxidizes adjacent molecules of 

 the oil. Other substances which accelerate the hardening are powdered 

 lead, zinc, copper, platinum or their oxides. This phenomenon depends 

 upon the very large proportion of unsaturated linkages which linseed 

 oil contains; it consists of a mixture of the glycerides of linoleic, 

 linoleinic and isolinoleinic acids (fatty acids of the unsaturated series 

 Cnltn-eQj) with a small proportion of oleic, palmitic and myristic 

 acids, and a trace of unsaponifiable material. 



Castor-oil is obtained by expression from the seeds or "beans" of 

 the castor-oil plant (Ricinus communis). It consists in the main of the 

 glycerides of ricinoleic acid Ci7H 32 (OH).COOH, a hydroxy-acid of 

 the unsaturated series. It is without aperient action until saponified 

 by the bile and pancreatic juice in the upper part of the sinall intestine 

 and is therefore devoid of irritant action upon the walls of the stomach. 



WAXES. 



In addition to the glycerides of fatty acids there are found in a 

 variety of living tissues and tissue-products, fatty acid esters of 

 monatomic alcohols which are collectively and somewhat loosely 

 designated Waxes. This term is not infrequently extended to include 

 the cholesterol esters of the fatty acids, for no better reason than that 

 cholesterol is a monatomic alcohol, and that the cholesterol esters 

 somewhat resemble the waxes in certain of their properties, more 

 particularly in the difficulty with which they are saponified. It would 

 be preferable, however, to restrict the term "wax," as we are doing 

 here, to the fatty acid esters of the higher monatomic alcohols of the 

 paraffin series. In this way we will include in the class all of the most 

 typical waxes of commerce, and we will exclude the entirely atypical 

 esters of cholesterol. 



The waxes are characterized by their high melting-point and the 

 difficulty with which they are saponified. They are not hydrolyzed 



