— 47 — 
of this important criterion for the purity and quality of French oils^ 
— a criterion which we have recommended on the strength of our 
examination of lavender oil, and of our observations made during a 
number of years, — Parry expresses the opinion that ''so far as he 
has been able to judge, the ester-value of lavender oils is by no means 
a certain index of the quality of the oil". 
The arguments adduced by Parry in support of his opinion, are 
partly the old ones. It may therefore suffice, if, with regard to these, 
we refer to our previous statements (Reports April 1898, 30, and 
October 1897, 3 1 to 35). The objection that linalyl acetate cannot 
be the most important body in lavender oil, because it has been 
identified as the bearer of the perfume in bergamot oil, and the two 
oils cannot be compared with one another, is all the more incom- 
prehensible, as it is not unknown to Parry that, although linalyl acetate 
occurs in preponderating quantity, the oil also contains other esters, 
which, jointly with the linalyl acetate, produce the ester-aroma of 
lavender oil. The ester-content calculated for linalyl acetate is, of 
course, only a comparative quantity, which no more indicates the true 
content of linalyl acetate than the quantity of the other esters present 
in lavender oil. This may perhaps be a defect in the method of 
examination, but it is proved in practice that it suffices for estimating 
the value of the oil. 
In addition to the substances capable of saponification, the other 
constituents of lavender oil are, naturally, also important for the pro- 
duction of the peculiar lavender-aroma; we would here refer only to 
coumarin^), detected by us in lavender oil, but it is equally 
certain that their perfume -value is not as high as that of the esters. 
If science should succeed in discovering also for these bodies a 
simple method of quantitative estimation, we would hail such discovery 
with joy; but even then the determination of ester would not lose its 
importance as the most essential factor in judging the value of the oil. 
In order to prove the unreliability of the ester- determination a& 
a basis for judging the odour-value of lavender oils, Parry has selected 
from a large number of pure oils of different origin, judging simply 
by the odour, those which appeared to him the best, and of these 
oils he has ascertained the ester -content. He finds, however, that 
the grouping of the oils according to their ester-value does not agree 
with the selection made by the nose. 
If this experiment by Parry has given an apparently unfavourable 
result for the method of estimating the ester, we are able to refer 
to facts which bear out exactly the reverse. 
In estimating the ester-content, coumarin is only incompletely saponified by 
alcoholic potash liquor. 
