Chapter III

).

Higher members of the formic acid series (as acetic, CH_{3}·COOH; propionic, C_{2}H_{5}·COOH; butyric, C_{3}H_{7}·COOH; etc.) are often found in small quantities in the leaves of many plants and seem to be characteristically present in certain species. They are easily produced from carbohydrates by bacterial action and, hence, are always present in fermenting tissues, such as silage, sauerkraut, etc. Furthermore, the glycerol esters of higher members of this and other monobasic acid series are constituents of all natural fats and oils (see