The valuation of such oils as bergamot and lavender according to their ester content has led to the occasional adulteration of such oils with cheaper esters or organic acids for the purpose of increasing their apparent ester content. Among the substances added for this purpose the following have been observed thus far: benzoic acid, salicylic acid, oleic acid, diethylsuccinate, triethyl-citrate, glycerylmonacetate, ethyltartrate and terpinylacetate.

The presence of acids can be detected by means of an increase in the acid value, which, in most oils, is very small. For this reason the advice was given on p. 571 to determine the acid value and the ester value separately. The acids can be isolated by shaking the oil containing them with dilute soda solution, separating the latter and decomposing the salt formed with a mineral acid.

1) Zeitschr. f. off. Chem. 9 (1903), 454. Comp. Chem. Zentralbl. 1904,1. 548.

The identification of the esters may be carried out in various ways. In most instances the oil is fractionated, the fraction to be examined saponified, and the attempt made to characterize the components. However, special methods are also employed varying with the kind of ester. Thus e. g. fractional saponification may lead to the detection of added terpinyl acetate. In consequence of the high specific gravity of the esters used for adulteration, such adulterated oils become suspicious in many instances because of their increased density. Details as to such adulterations will be found in the second volume under the respective oils.