— 60 



Esters with readily volatile acids (terpinyl acetate and glyceryl acetate). 



Esters of which the acids are less volatile (succinic acid ester, oxalic 

 acid ester, tartaric acid ester and citric acid ester 1 ). 



In spite of many experiments we were unable to discover a general 

 method of examination for the determination of the esters of the first 

 group. It was only possible to detect on the one hand an addition of 

 terpinyl acetate and on the other, of glyceryl ester, was found by a 

 series of experiments that in the case of pure linalyl acetate the saponi- 

 fication with alcoholic seminormal potash liquor is almost entirely com- 

 pleted after only 15 minutes heating on the water bath, whereas in the 

 case of pure terpinyl acetate the ester number may be very considerably 

 increased by prolonged saponification. 



The experiments which enter into consideration here are enumerated 

 in the following table: — 



Time of saponification 



5min. 



15min. 



30min. 



45min. 



1 hr. 



2hr. 



Linalyl acetate Schimmel 8j Co. E. No. 



191,5 



217,5 



223,2 



223,7 



223,1 



224,7 



Terpinyl acetate „ 



108,2 



166,8 



209,7 



233,4 



245,8 



262,7 



Bergamot Oil „ 



80,3 



94,5 



97,3 



97,5 



97,8 



98,5 



„ -f- 5°/o Terpinyl acetate „ 



82,5 



94,8 



101,2 



102,1 



104,7 



107,2 



+ 10°/o 



79,9 



96,4 



102,8 



105,2 



108,3 



112,5 



+ 25 °/o 



78,8 



100,6 



108,1 



116,4 



119,0 



126,8 



Only one example out of a whole series of bergamot oils which have 

 been tested by this method is included in the table given above, because 

 all these tests gave equally high ester numbers after one-half to 1 hour's 

 boiling, whereas a bergamot oil with an addition of 5°/o terpinyl acetate 

 gave the ester numbers 101,2 and 104,7, a difference of 3,5 between the 

 two numbers. When 10°/o terpinyl acetate was added the difference was 

 5,5; with 25°/o it was 10,9. It is clear from these figures that as the 

 terpinyl acetate content is increased the saponification, given the same 

 duration of the saponification-process, becomes more and more incomplete. 



In the case of two adulterated bergamot oils which had been examined 

 previously 2 ) the ester numbers after x / 2 and 1 hour's saponification were 

 96,8 and 109,2, and 94,7 and 111,3 respectively. For these oils the difference 

 between the two values was 12,4 and 16,6. In view of the results of 

 the present investigation we are able to correct our previous estimate, 

 which placed the extent of admixture to these two oils at 4,3 and 5,9 °/o 

 terpinyl acetate at the lowest, and to state that these oils contained about 

 30°/o terpinyl acetate. 



Jeancard and Satie 3 ), and more recently Heine $ C2 4 ), have called 

 attention to the use of glyceryl acetates as adulterants. The detection 



!) Report April 1907, 66. 



-') Report April 1910, 58. 



3 ) Bull. Soc. chim. IV. 3 (1908), 155; Report April 1908, 64. 



*) Seifensieder Ztg. 37 (1910), 750. 



