The occurrence of n-heptadecanoic acid (margaric acid) in hydrogenated mutton fat.

Although the isolation of n-heptadecanoic acid (margaric acid) from natural fats has often been reported (cf. Ralston, 1948), there appears to be no case on record where the identification of the acid from these sources has been irrefutably established. Ralston (1948) states: 'All the naturally occurring heptadecanoic acids which have been described and subsequently investigated have been shown to consist of mixtures of palmitic and stearic acids. Because of the frequent mutual occurrence of palmitic and stearic acids in fats, and since they are often the chief saturated acids, it is not surprising that a mixture of them has frequently been identified as a pure compound.' Not only has the presence of margaric acid in fats been unsubstantiated, but so also has the presence of the other straight-chain odd-numbered fatty acids with the exception of the recently reported steam-volatile acids of ox perinephric fat, which were shown to contain trace amounts of all the straight-chain acids (both odd and even) from C2 to C1O (Hansen & McInnes, 1954). This latter work has prompted further investigations into the minor components of fats, and as a preliminary to a comprehensive search for oddnumbered straight-chain acids the 'solids' from a sample of hydrogenated mutton fat (external carcass fat) have been investigated and have yielded margaric acid. Brief reference to this finding has already been made (Hansen, Shorland & Cooke, 1954). From the same original material