128 Report of Schimmel «j Co. April 1913. 



our Report of October 1910 (61) that it is capable of detecting the presence of even 

 1 p. c. glyceryl acetate in bergamot oil, and that, if carried out according to the 

 instructions given, an addition of 1 p. c. glyceryl acetate increases the quantity of KOH 

 used up by about 15 milligrams (= 0,54 cc. seminormal potash liquor). In the case 

 of two samples of bergamot oil to each of which 2 p. c. glyceryl acetate had been 

 added, Salamon and Seaber used up respectively 1,3 and 1,8 cc. seminormal potash 

 liquor in order to saponify the alcoholic solution, which would represent about 2 to 

 3 p. c. glyceryl esters. These values approximate very closely to the facts. 



S. Godfrey Hall and A. J. Harvey 1 ) have recently published another method for the 

 quantitative estimation of glyceryl esters in bergamot and lavender oils. Put briefly, 

 this method is based upon the direct separation and estimation of the glycerol. The 

 authors proceed as follows: — 



A known quantity of oil (not less than 10 grams if possible) is mixed with 50 cc. 

 alcohol, (sp. gr. 0,830) and saponified with seminormal potash-liquor. After being 

 digested for one hour on the water-bath the solution is neutralised with seminormal 

 hydrochloric acid, evaporated to dryness on the water-bath, and the residue diluted 

 with about 20 cc. water and extracted with methylalcoholic ether to remove the oily 

 portions. The ether-solution is again shaken out with 10 cc. water, added to the 

 aqueous extract, and the whole evaporated to a syrupy consistency. If the original 

 oil was adulterated with glyceryl ester, the remaining residue must contain the corre- 

 sponding glycerol, of which the quantity is estimated by acetylation. In order to accomplish 

 this the residue is diluted with 3 grams fused sodium acetate and 8 cc. acetic anhydride 

 and heated for one hour in a reflux-condenser. It is then cooled, 50 cc. boiling water 

 is added, the whole brought to a temperature of 80°, again cooled, and finally filtered 

 quantitatively into another vessel, by rinsing with water. After adding a few drops of 

 phenolphthalein solution the excess of acetic acid is neutralised lege artis with a 5 to 

 6 p. c. soda liquor and the mixture saponified with seminormal soda liquor, being boiled 

 gently for 15 minutes in a reflux condenser. After cooling the excess of liquor is 

 titrated back with seminormal hydrochloric acid and the quantity of glycerol or glyceryl 

 acetate calculated from the alkali used up (1 cc. seminormal soda liquor corresponds 

 to 0,01535 grams glycerol and 0,03641 grams glyceryl acetate). It is advisable to make 

 a blank test at the same time, and for this 5 cc. of the seminormal liquor is used. 

 Hall and Harvey have tested their method with bergamot and lavender oils, to which 

 they had added 2 and 5 p. c. glyceryl acetate respectively and have obtained excellent 

 results, as is shown in a table added to their paper. 



As mentioned in another part of the present Report (p. 62), F. D. Dodge utilises 

 the stability of eucalyptol towards 5 to 6 p. c. potassium permanganate solution in the 

 cold for the purpose of the quantitative estimation of eucalyptol in oils of eucalyptus 

 and cajuput. He has now experimented with this method in order to ascertain its 

 value for other essential oils, and, has reported the results of his investigations to 

 the Eighth International Congress of Applied Chemistry, which assembled in New York 

 in September 1912 2 ). 



According to Dodge's experience the process, when applied in the cold, usually 

 takes a quantitative course. Among the more common constituents of essential oils 

 only the following remain unattacked, viz., camphor, fenchone, bornyl acetate, menthyl 



1 ) Journ. Soc. chem. Industry 32 (1913), 61. — 2 ) 8th. International Congress of Applied Chemistry, 

 Washington and New York, 1912, Vol. VI, 86. 



