— 64 — 



to contain about 2° of the said ester. The extent of the difference 

 ascertained by the above method confirms this result, inasmuch as the 

 difference 16,8 of the oils approximately agrees with the number 18,4 of 

 the pure bergamot oil (No. 21) to which 2% citric acid ester had been 

 added. Citric acid ester was also detected in oils Nos. 8 and 9 which were 

 suspect on account of their high difference values. 



On the basis of what has been said above the most practical method 

 of testing bergamot oil for foreign esters is as follows: — For the sapo- 

 nification three tests should be made, one of which should be titrated after 

 30 min., the two others after one'hour's, saponification. If the saponification 

 numbers agree, adulteration with terpinyl acetate is out of the question. If 

 they do not, a difference of up to 2 should be regarded as being within the 

 limits of error, and the tests should be repeated. When the difference exceeds 

 2 the extent of the addition of terpinyl acetate may be gathered approximately 

 from the above table. Further, the acid number II should be determined 

 from one of the samples which have been saponified for an hour by 

 distilling with steam and comparing the result with the saponification 

 number. If the difference exceeds 7 adulteration with the esters of 

 sparingly volatile acids is probable. If the difference exceeds 10, adul- 

 teration may be assumed as proved. If sufficient material is available, 

 the acid in question ought to be traceable without much difficulty 1 ). The 

 test for esters of glycerol should be carried out as described above. 



The method here described may perhaps be found generally applic- 

 able to the detection of adulteration with the esters in question, for 

 example in lavender oil and petitgrain oil, of which the value is also 

 estimated by their ester-content. We are still engaged in examinations 

 in this respect with these oils. 



Some new constituents of bergamot oil are mentioned by F. Elze 2 ). 

 This author has examined a fraction which was obtained to the extent of 

 25°/o in the course of the commercial manufacture of terpene-free berga- 

 mot oil. After saponification, distillation by steam and fractionation, the 

 sample presented an oil possessing the following properties: di 5 o 0,890, 

 a— 10° (in a 100mm. tube). The oil was treated with phthalic acid an- 

 hydride, by which method a small quantity of an alcohol was obtained 

 which proved to be dihydrocuminic alcohol (m. p. of the naphthylurethane 

 146 to 147°). After oxidising with Beckmann's chromic acid mixture this 

 alcohol yielded an aldehyde boiling at 235°, with an odour resembling 

 cumin. Regenerated from the semicarbazone (m. p. 198 to 199°), its con- 

 stants were di 50 0,970 and « D — 39° (in a 100 mm. tube). The principal 



*) Report April 1897, 25; April 1905, 51 ; the present Report, p. 58. 

 2 ) Chem. Ztg. 34 (1910), 538. 



