220. SUCCINIC ACID. 231 



ingly dissolved by alcohol, and to but a very slight extent by 

 ether. The occurrence of succinic acid is frequently mentioned 

 in plant-analyses of less recent date, but in many instances confir- 

 mation of such statements is required. And even if that were 

 forthcoming, the question might be raised as to whether the acid 

 had not been produced by a process of fermentation that might 

 have taken place during the manipulation. 



The following reactions may serve for the identification of 

 succinic acid : 



" Chloride of barium precipitates from a solution of an alkaline 

 succinate (in presence of alcohol) a crystalline barium- salt, which 

 is soluble in about 250 parts of water, but almost insoluble in 

 alcohol. Hydrochloric acid dissolves it, but acetic acid takes up 

 only small quantities at the ordinary temperature. 1 



Chloride of calcium also throws down a crystalline salt from 

 concentrated solutions of alkaline succinates. The precipitate 

 dissolves, according to Barfoed, in about 50 parts of water, but is 

 very sparingly soluble in alcohol. If the precipitation takes place 

 in the presence of alcohol the salt is at first amorphous, and subse- 

 quently assumes a crystalline condition. It dissolves in warm 

 dilute acetic acid, and in boiling solution of chloride of ammonium. 

 (Distinction from oxalic acid.) 



Succinate of lead is likewise crystalline, but complete separation 

 takes place very slowly. Basic acetate of lead throws down an 

 amorphous salt. Ferric chloride produces brownish-red amor- 

 phous precipitates in solutions of normal alkaline succinates, but 

 does not form insoluble compounds with oxalates. 



In separating oxalic from succinic acid advantage may be taken 

 of the solubility of ammonium succinate in spirit. Barfoed 

 separates tartaric from succinic acid in the form of acid tartrate of 

 potassium in the presence of hydrochloric acid and alcohol. Or 

 it may be precipitated by mixing the hot solution with chloride 

 of ammonium, adding chloride of calcium and cooling. Citric acid 

 may be separated in a similar manner, but in this case the mixture 

 must be boiled until the whole of the citrate of calcium has been 

 thrown down; or the solution may be boiled with chloride of 

 barium and filtered whilst hot from the precipitated citrate of 

 barium. The filtrate contains the succinate of barium, which can 

 be thrown down by alcohol after cooling ( 215). 

 1 See Barfoed, loc. tit. 



