298 

 OILS AND FATS. 



BY CAMPBELL MORFIT. 



Although some fatty bodies are very different from others in their 

 chemical nature, and all of them differ from the essential oils, yet being 

 often used in the same branch of manufacture indiscriminately, they 

 may be embraced together as a class under the term Oleics. 



By far the larger proportion of oils and fats agree in being composed 

 of a fat acid, united to a base called glycerine. The three principal acids 

 are stearic, margaric, and oleic ; when stearate or margarate of glycerine 

 predominate (the compound being called stearin or margarin), the fat is 

 more solid, as tallow, suet, &c. ; when oleate of glycerine (called also 

 olein) is in sufficient quantity, the fat is fluid or oily, as olive oil. The 

 chemical connection between margaric acid, which is a solid crystalline 

 fat, and vinegar or acetic acid, and the connection between acetic acid 

 and common alcohol, are pointed out in an essay published in the 

 ' Journal of the Franklin Institute,' 1848. Now since formic, acetic, and 

 valeric acids can be shown to be derived from wood-spirit, common 

 alcohol, and fusel oil, which are their respective alcohols, we may infer 

 that the higher fat acids have also their alcohols. The investigations of 

 Brodie in wax seems to point out such alcohols and their acids. The 

 general formula for this fat acid series, the most extended series yet 

 developed in organic chemistry, is Cn H n O4, n being an even number. 

 No well-defined connection has yet been established between other fat 

 acids not belonging to this group. 



According to Georgey ('Ann. der Chem. und Pharm.' lxvi.), the 

 butter of cocoa contains the following acids : 



Caproic C12H12O4 



Capryllic CieHieOi 



Capric C20H20O4 



Pichuric (lauric, laurostearic) . . . C24H24O4 



Myristic (probably) C28H2SO4 



Palmitic C32H32O4 



The cocinic acid of St. Evre is a mixture of capric and pichuric 

 acids. 



Gerhardt and Laurent have endeavoured to prove (' Comptes Rendus,' 

 1849) that the formula for stearic acid is C34H34O4 ; that margaric acid 

 is an isomeric modification of it, and should be called metastearic acid. 



The train-oil of the Beaked Whale {Balcena rostrata) has recently 

 been examined by Scharling (' Journ. of Prac. Chem.' xliii.), who gives it 

 the formula CfeHeoO 4 - It consists principally of a liquid fat, free from 

 glycerine, a minute portion of spermaceti, and traces of other fats. Its 

 specific gravity is -8807 at 52°. It burns with a bright flame, and its 

 illuminating power is in the ratio of 1.57 : 1 of common whale oil. It 

 also barns slower and emits less smoke than the latter oil. 



