— 30 — 
oil examined by him from the specific gravities of the components 
estimated quantitatively, and places them against the values determined 
by scale But Spurge leaves here out of account that both the 
values obtained for eugenol by Verley-Boelsing's method, and those 
for eugenol acetate obtained by saponification, represent percentages 
by weight, whilst Spurge deals with them as if they were percen- 
tages by volume. A re-calculation shows that the values calculated 
in the correct manner still more closely approach those determined by 
balance than Spurge mentions. 
In our last Report (page 27) we have expressed ourselves in 
detail on the question of the determination of eugenol in clove oil, 
and it is therefore sufficient to refer here in a general way to the 
statements made by us at the time. We are of opinion that the un- 
corrected but modified method of Umney gives results of a suffic- 
iently satisfactory character, and on account of its ready feasibility 
should be preferred in practice over other methods, as the latter 
also leave something to be desired in the exactness of their results. 
We can confirm Spurge where he says that by Umney's method 
esterified eugenol is also determined in addition to the free eugenol; 
but the experiments made by us with mixtures of eugenol, eugenol- 
acetate, and caryophyllene, have shewn that a quantitative saponi- 
fication of eugenol acetate only occurs in the mixtures of high per- 
centage (above 90 per cent, eugenol), whilst with a lower content of 
free eugenol a corresponding smaller quantity of eugenol acetate is 
saponified. This is shown most clearly in the following table: 
Eugenol 
Eugenol 
Caryo- 
Eugenol-determination 
Acetate 
phyllene 
with 3 7„ NaOH 
I. 
96% 
2% 
98% 
II. 
92 7o 
4% 
4 7o 
96% 
III. 
80% 
io7o 
87% 
42 7o- 
IV. 
40% 
50% 
The different behaviour of the richer mixtures as compared with 
those less rich in free eugenol, can be explained in this manner, that 
the eugenol sodium formed, dissolves in the first place a definite 
quantity of eugenol acetate, and that the portion of the ester present 
in the solution is then saponified by the soda liquor. 
As clove oils contain but rarely less than 80 per cent, free eugenol, 
it is sufficient for practical purposes to assume that in Umney's 
method the free as well as the total esterified eugenol are estimated, 
^) On this occasion the constants of eugenol acetate prepared by himself are 
also given: d^5° = 1,089; boiling point 160° to 162° (19 to 20 mm). In our labor- 
atory we determined the following values: dj^° = 1,087; ^d^qo = 1,52069: melting 
point 29°; boiling point 142° to 143° (6 mm). 
