Ester value

The principal adulterant of this oil it ordinaiy turpenline, which, of course, reduces che ester value, aud yields a large amount of discilUce Imlow llirA... 

Oil dislilkd in tbe Fiji li-kuds ha - a -syfccitic i-aviis 101 S lo I OSOh. acid value about 3C, usfi i value about 17. tuid ester value afu-i aceiylatioi about 14,1. lo all otb r i-i-a[i ias it coi respouds vi b l-liii-o[>eaii dl-.Lil p(l oil. 

Its ester value was 41-2, atiil enter value alter acetylation 63 J. Schimmel f. o.- have examined the oil obtained from cardatnoiri roots from Indo-Cbina. They ohtain-J 0 04 ptv ueni. of oil haviug the following characters 0"9(>0li ud -. 12 57 iicrm- l 4nlo I acid value... 

The acid value of this on it alwavs below 1 and the ester value does not exceed 2 5.. A large amount of free alcohols, Uow.wcr, is present, the ester value after acetylation vaning from -16 m 129. 

Lavender oil is practically neutral.. Au acid valne over about 3 in-dicateR the addliion ct oaidR, such as benroic orsalic.vHc added, to bring up tbe apparent ester value. 

Oils are not iuftequently lound with a very high ester value, foUowing being amongst those so rccordad. 

On evaporation oti a watcr-batb, sweel orange oil yields from J-.O lo 4 per cent, ot fixed ru.sidue, which has an acid value of H to 30 and an ester value of li-o lo 170. Spanish orange oil, however, which is expressed From a dark-skinned orange, yields from 7 to 0 pur cent. o[ fixed... 

This action is reversible, so that to maintain the ester value it is obvious that the removal of water is advantageous. As a matter of fact, if transpiration is increased, or the absorption of moisture by the roots is diminished, the esterification is more rapid. 

Specific gravity. Refractive index at 20° Ester value... 

Strictly speaking the amount of free acids present in an essential oil should be determined, and the acid value deducted from the saponification value, the difference being the ester value. 

The high saponification value of these two bodies render them particularly suitable for adulteration, a small proportion being sufficient to materially raise the ester value. 

Terpinyl acetate in the absence of esters of high molecular weight, or ethyl esters of the fatty acids of coconut oil, is indicated by a difference to be observed in the apparent ester value by different times of saponification. This ester is far more resistant to the action of caustic alkali than is linalyl acetate, and requires two hours at least for complete saponification. Hence, if the oil shows a difference in the saponification value in thirty minutes and in two hours, which amounts to more than from 1 to 2, terpinyl acetate is almost certainly present. The following table shows the effect of this partial-saponrfication on the two esters and on adulterated oils —... 

Glyceryl acetate is so easily washed out with ordinary hot distilled water, that an adulterated oil when washed several times with hot water will show a distinctly lower ester value and refractive index than the original unwashed oil. 

Pure oils of lavender, bergamot and similar oils show practically no reduction either in refractive index or ester value by such treatment. 

Note 4 If the acidity of the ester exceeds 0.01% by wt as free acetic acid (See opn 5 of FedSpec TT-E-751C), a suitable correction must be applied to the ester value... 

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