— 61 — 



of this sophistication is based upon the comparatively ready solubility of 

 these esters in water. When a bergamot oil which had been adulterated 

 with these esters is shaken with water in a suitable manner, a certain 

 percentage proportion of the glyceryl acetate contained in the oil goes 

 into solution. The quantity of added ester may then be calculated after 

 saponification of this aqueous solution with potash liquor from the quantity 

 of alkali consumed. 



This test is carried out as follows: 10 cc. bergamot oil is mixed in 

 a separating funnel with 10 cc. light petroleum and 2,5 cc. alcohol, and 

 vigorously shaken up with 20 cc. water. The addition of light petroleum 

 and alcohol causes a very rapid separation of the oil and the aqueous 

 liquid, so that the latter can be filtered off when the mixture has been 

 allowed to settle for about 10 minutes. Of the filtrate 10 cc. is neutralised 

 with potash liquor and saponified on the water bath for one hour with 

 5 cc. seminormal potash solution. In the case of pure bergamot oil the 



10 cc. of filtrate required for saponification 



0,08 cc. seminormal potash liquor = 2,2 mg. KOH. 



After adding l°/ glyceryl triacetate, 0,58 cc. =16,2 „ „ was used. 



2 1 h°lo n » M3 „ =40,0 „ 



i? v 5 /o „ „ 2,7 J „ = 78,0 „ „ „ „ 



Hence the addition of 1% glyceryl triacetate requires about 15 mg. 

 KOH more. 



For the second group of esters which are used as adulterants we have 

 devised a method of examination which is based upon the exceedingly 

 slight volatility with steam of the acids contained in these esters. The 

 examination of pure bergamot oil has shown that almost the whole of 

 the acid which is combined with the potassium hydroxide by saponi- 

 fication can be distilled off with steam after acidulation of the aqueous 

 solution with sulphuric acid. With pure bergamot oils, therefore, only a 

 little more potash liquor is used up in determining the saponification 

 number than is required for neutralising the acids which have been distilled 

 off. The determination is carried out with 1,5 to 2,0 g. oil as follows: — 

 The acid and ester numbers are ascertained in the usual manner, and 

 the contents of the saponification flask evaporated to dryness after adding 

 a few drops of seminormal potash liquor. The residue is dissolved in 

 about 5 cc. water and acidulated with 2 cc. dilute sulphuric acid. From 

 a flask A (as shown in the accompanying illustration), fitted with an 

 ascending tube, a powerful current of steam is generated, by which, in 

 the space of half an hour, 250 cc. is distilled over into the measuring 

 flask O, in such a manner that the contents of the saponification flask B> 

 are kept down to about 10 cc. with a small flame. Afterwards 100 cc. 

 more is carried over in the same manner. The distillate, after a few drops 

 phenolphthalein solution with seminormal potash liquor (or for the sake 



