1818.] M. Vauqudin on Sorbic Acid. 293 



If the sorbate of lead be obtained by double affinity, it affords 

 different results ; in this case it consists of 



Sorbic acid 32*57 



Oxide of lead 67-43 



100-00* 



M. Braconnot is, however, inclined to suppose that the salt 

 obtained by double decomposition is a mixture of the neutral 

 sorbate and the sub-sorbate, because the oxygen in the oxide 

 of lead which saturates 100 parts of sorbic acid is 1 1-253 accord- 

 ing to the first analysis, and 14-7 according to the second. 

 Sub-sorbate of lead may be procured by digesting ammonia upon 

 the neutral sorbate of lead ; the sub-sorbate does not form a hard 

 or granular mass with boiling water, as is the case with the 

 neutral sorbate. M. Braconnot has also formed the sorbates of 

 strontian, barytes, magnesia, alumine, and the protoxide and 

 deutoxide of mercury, of silver, copper, iron, manganese, and 

 tin ; these salts are very soluble, uncrystallizable, and deliques- 

 cent. 



Experiments on the Sorbic Acid. By M. Vauquelin.+ 



In the year 1816 Mr. Donovan discovered in the fruit of the Sor- 

 bus Aucuparia a new acid, possessed of specific properties ; and 

 also announced that this acid exists in other vegetables. M. Vau- 

 quelin has repeated the experiments of Mr. Donovan ; he has 

 confirmed the discovery of the new acid, and has made a number 

 of observations upon it, which had not been noticed by the 

 discoverer. 



The author began by obtaining a very large quantity of the 

 juice of the ripe Sorbas, no less than 50 quarts. :£ The juice, 

 when recently procured, is viscid, so as to pass with difficulty 

 through a filter ; but by remaining for about a fortnight in a warm 

 temperature, it experiences the vinous fermentation. It then 

 becomes bright and clear, easily passes through the filter, while 

 a quantity of yeast is separated from it. By distillation, a 

 portion of alcohol, of a specific odour and flavour, may be pro- 

 cured from the fermented juice, whence it is inferred that the 

 recent juice must have contained saccharine matter. The sorbic 

 acid itself does not appear to be affected by this fermentation. 

 No malic acid could be detected in the recent juice of the sorb. 

 The viscidity of the recent juice did not appear to depend, in 



* The estimate agrees very nearly with Vauquelin's, who also formed his sor. 

 bate of lead by precipitation. — Ed. 



+ Abridged from Ann. de Chim. ct Pliys. torn. vi. p. 337. (Dee. \8\T,) 

 + The readers will observe that M. Vauqueliu differs from M. Braconnot in 

 employing the fruit in its ripe slate; it remains to be determined whether this 

 circumstance was the difference which was observed between the substance as pro- 

 cured by these chemists Ed, 



