NOTES ON SCIENTIFIC RESEARCH. 61 
linalyl acetate, after a saponification of 3 hours in the heat and of 24 hours at room 
temperature, contents of 85.5 and 80.3 p.c. were found: difference —5.2. The differences 
were: 15.7 p.c. for a mixture of 75 p.c. of linalyl acetate and 25 p.c. of terpinyl acetate, 
30.1 p.c. for the proportion 1:1, 46.4 p.c. for 1:3 and 59.5 p.c. for pure terpinyl acetate. 
Bergamot oil and a mixture of bergamot oil with orange oil terpenes and linalyl 
acetate did not show any difference when treated in the same manner in the heat 
or in the cold; but when a mixture of 70 p.c. of bergamot oil, 20 p.c. of orange oil 
terpenes and 10 p.c. of terpinyl acetate was used, the difference amounted to 4.6 p.c. 
The differences became still more noticeable at 0°. The quantity of potash lye and 
its concentration likewise influence the result of the saponification. Thus 25 cc. of 
N,2 potash lye saponified, in 48 hours at 14 to 15°, 84.2 p.c. of linalyl acetate and 
49.6 p.c. of terpinyl acetate, but oie cc. of oe potash lye only 39.2 and 10.4 p.c., 
respectively. 
For the determination of terpinyl acetate in linalyl acetate or adulterated bergamot 
oil, the authors suggest to heat in each case 1.5 g. of the ester with 25 cc. of 
alcoholic N/2 potash lye for 3 hours and then let the mixtures stand for 24 hours 
at 15 to 16°. 
In the case of adulterated bergamot oils the results are more exact. The saponi- 
fication of normal bergamot oils with 35 to 40 p.c. of linalyl acetate at 15° is completed 
in 24 hours. A difference of more than 1 p.c. in the results of saponification points 
to an adulteration with terpinyl acetate, ‘but the quantity of the adulterant cannot be 
established exactly in this way. 
Of the experiments mentioned are specially interesting only those referring to the 
saponification of linalyl acetate and geranyl acetate at room temperature, for it results 
that the rate of saponification in the presence of alcohol is considerably higher for 
geranyl acetate than for linalyl acetate, which was not to be expected from the outset. 
This is probably due to that the alkali does not act direct on the original ester, but 
on the ethyl acetate formed intermediately’), and that this change takes place more 
quickly with geranyl acetate than with linalyl acetate. 
We do not see, however, any reason for modifying the method recommended by 
us for the detection of terpinyl acetate, for it is easily carried out and has proved to 
be good in the course of years. There are no advantages connected with the proposal 
of Barillet and Berthelé, the process recommended by them taking far more time without 
giving any better results than ours. For instance, we found by means of our method 
of ftactional saponification a difference of 19”), corresponding to 6.65 p.c. of ester, in 
bergamot oil to which 10 p.c. of terpinyl acetate had been added, whereas the French 
authors stated a difference of only 4.60 p.c., when examining after their own method 
the mixture of 70 p.c. of oil of bergamot, 20 p.c. of orange oil terpenes ae 10° pics OF 
terpinyl acetate, previously mentioned. 
Quantitative determination of hydrocyanic acid. 
When examining parts of plants for their content of hydrocyanic acid, one generally 
has to deal with extremely small quantities of this acid. The analytical methods with 
the aid of silver nitrate usually fail in this case, as the aqueous distillates nearly always 
contain reducing compounds in addition to the hydrocyanic acid. Qualitatively, the acid 
is determined through the Prussian blue reaction, which may likewise be used for the 
4) Comp. A. Béhal, Bull. Soc. chim. IV. 15 (1914), 565; Report April 1915, 68. — 7) Report October 
1911, 117. \ 
