682 



stant boiling point at 220 C. Freshly distilled, the oil is colourless, 

 but it soon acquires a yellowish tint. It has a peculiar aromatic 

 odour, not disagreeable when dilute, but rather offensive when con- 

 centrated. The specific gravity is 1-0681. It is somewhat soluble 

 in water, very soluble in alcohol and ether ; these solutions are di- 

 stinctly acid. The oil dissolves in potassa and ammonia, also in the 

 carbonated alkalis, without, however, expelling their carbonic acid. 

 Mineral acids separate it again from these compounds. 



The analysis of the oil shows that it contains carbon, hydrogen, 

 and oxygen in the ratio of 



C 3 H 2 0; 



but the determination of the silver in a white amorphous silver com- 

 pound, obtained by adding nitrate of silver to the ammoniacal solu- 

 tion of the oil, shows that this expression must be quadrupled, arid 

 that the acid and silver salt are represented by the following 



formulse : 



Acid . . C 12 H 8 4 



Silver-salt C 12 [H 7 Ag]O 4 . 



The acid oil of the mountain-ash berry exhibits a very remarkable 

 deportment with the alkalis and acids. When gently heated (a 

 temperature of 100 is sufficient) with solid hydrate of potassa, or 

 when boiled with concentrated hydrochloric or moderately dilute 

 sulphuric acid, the oil is readily converted into a splendid crystalline 

 acid, greatly resembling benzoic acid in its general characters, which 

 has the same composition as the oil itself. I have established this 

 remarkable isomerism both by careful observation of the conditions 

 of transformation, and by the analysis of the crystalline acid as well 

 as of some of its salts and derivatives. I propose to designate this 

 new compound by the term sorbic acid, thus reviving an old name 

 which had at one time been used for malic acid. The isomeric oil 

 obtained by distilling the juice of the mountain-ash berry, the acid 

 properties of which are much less pronounced, may then be called 

 Parasorbic acid. 



Sorbic acid. This substance is readily soluble in alcohol and 

 ether, less so in water. Heated with a quantity of water insuffi- 

 cient for solution, it fuses ; the aqueous solution, saturated by ebul- 

 lition, solidifies on cooling into a network of interlaced needles. The 

 acid crystallises best from a mixture of alcohol and water, in which 



