— 79 — 
examined is dissolved in three parts anhydrous ether, and semi-normal 
alcoholic potash solution is added. If phenols etc. are absent, no 
separation takes place after adding a certain quantit}^ of potash; 
but if phenols or salicylic acid ester are present, the mixture becomes 
cloudy, and the potassium compounds are separated off in fine crystals. 
The phenol-content can be readily determined by decomposing the 
filtered and washed compounds with acids (preferably carbonic acid). 
If it is desired to estimate the alkali titrimetrically in the precipitated 
compound, — especially in smaller quantities — , it is necessary to 
avoid carefully too large an excess of potash liquor. The advantages 
of this method (which is being submitted to a thorough study) are, 
according to Hesse, that the risk of saponifying the esters present 
is diminished, and further that the determination is made with two 
miscible liquids, that is to say, different from the usual method of 
extracting the oil with aqueous solution. 
In the same place Hesse mentions the high content of methyl 
ester of methyl anthranilic acid in an oil from mandarin leaves, which was 
found to be 65 ^/q, against a content of 50 ^/q mentioned by Charabot^). 
There was further observed the presence of a very small quantity of 
a base with a nicotine-like odour, which could not be saponified. It is a 
remarkable fact that the ester does not occur in the leaves of the 
closely allied lemon tree. 
In the same journal Hesse discusses 2) the more recent observations 
made in the industry of essential oils. During the last few years the 
technology of odorous substances has applied itself preferably to the 
imitation of valuable natural oils, and in many instances has been able 
to show good results in this domain. This imitation is based in the first 
place on the exact knowledge of the composition of the oils, — com- 
positions which frequently are most complicated. In spite of the highly 
improved methods of examination, the chemical investigation of many 
precious oils has hitherto not been successful in isolating the characteristic 
bearers of the odour, which mostly occur only in extremely minute 
quantities; for this reason the fundamental hypothesis of the synthesis of 
complex odoriferous bodies, the determination if possible, quantitative of 
the composition of an oil, can be accomplished only in the rarest cases. 
The industry of the artificial oils has been promoted (in Germany) 
by the granting of so-called application-patents, which protect partly 
the imitation of the natural products, and partly the application of 
individual constituents which have been detected scientifically. The 
facts have shown that the natural oils have by no means been supplanted 
^) Compt. rend. 135 (1902), 580. Report April 1903, 38. 
Chem. Zeitschrift 2 (1903), 697, 728. 
