186 CITRIC ACID. 



phuric acid. Direct evaporation of the juice does not 

 yield the acid in a crystalline form, on account of the 

 presence of other substances. 



Properties. Colorless, transparent, rhombic prisms, 

 of a strong, agreeable, acid taste ; easily soluble in 

 water. Fuses at 100 in its water of crystallization, 

 in an anhydrous condition at 153-154. Its solution 

 is not precipitated at the ordinary temperature by lime- 

 water, but the precipitation ensues on heating the 

 solution. 



Potassium citrate (neutral), C 6 H 5 7 K 3 + H 2 0, 



clear deliquescent needles, insoluble in alcohol. Mon- 

 acid salt, C 6 H 5 7 HK 2 , white, amorphous, easily soluble 

 mass, is produced by evaporating the mixed solutions 

 of 2 molecules of the neutral potassium salt with 1 

 molecule of free citric acid. Diacid salt, C 6 H 5 7 H 2 K 4- 

 2H 2 0, large, transparent prisms, soluble in water and 

 alcohol, is formed, when citric acid is added to a solu- 

 tion of the neutral salt, in double the quantity in 

 which it is already present in the salt, and then the 

 whole evaporated. 



Calcium citrate, (C 6 H 5 7 ) 2 Ca 3 +4H 2 0. Fine, crys- 

 talline powder, difficultly soluble in water ; is precipi- 

 tated by heating its solution, 



Silver citrate, C 6 H 5 7 Ag 3 , White flocculent pre- 

 cipitate, insoluble in water, is decomposed by boiling 

 with water, 



Methyl citrate, C 3 IP(OH) -{ (CO.O.CH 3 ) 3 , and Ethyl 

 citrate, C 3 H 4 (OH) -j (CO.O.C 2 !! 5 ) 3 , are formed by con- 

 ducting hydrochloric acid into solutions of citric acid 

 in methyl or ethyl alcohol. Compounds not volatile 

 without decomposition, The methyl ether crystallizes ; 

 the ethyl ether is oleaginous. 



Ethyl acetylcitrate, C 3 H 4 (O.C 2 H 3 0) -{ (CO.O.C 2 H 5 ) 3 , 

 is formed by the action of acetyl chloride on ethyl 

 citrate. ^A liquid, insoluble in water, boiling at 288. 



