362 PHTALIC ACID. 



from the broken-up bark, with water or dilute sul- 

 phuric acid, is treated with milk of lime in order to 

 precipitate the alkaloids. The filtered solution, on 

 being evaporated, leaves calcium quinate behind, and 

 this may be purified by recrystallization, and then 

 decomposed by oxalic acid. 



Transparent, colorless, oblique rhombic prisms. Easily 

 soluble in water, but very slightly in. absolute alcohol ; 

 fuses at 162, and, when heated above its fusing point, 

 yields hydroquinone, pyrocatechin, benzoic acid, phe- 

 nol, and other products. Oxidizing agents (manganese 

 peroxide and sulphuric acid) resolve it into quinone 

 (p. 301), carbonic anhydride, and formic acid. Heated 

 with concentrated hydriodic acid, it is reduced to 

 benzoic acid. "When quinic acid is taken into the 

 system of man or graminivorous animals, it is con- 

 verted into hippuric acid. 



Monobasic acid. All its salts are soluble in water. 



Calcium quinate, (CT^OyCa + 10H 2 0, forms 

 large, easily soluble rhombic crystals, that effloresce in 

 contact with the air. Is contained in cinchona barks. 



e. Bibasic Acids. 

 1. Benzenedicarbonic Adds. 



1, Phtalic acid (Ortho-phtalic acid) is produced by 

 the oxidation of naphthalene and several of its deriva- 

 tives ; also of alizarin and purpurin with nitric acid or 

 black oxide of manganese and sulphuric acid. Is also 

 formed by treating benzene or benzoic acid with black 

 oxide of manganese and sulphuric acid. Colorless 

 laminae, or short, thick prisms; difficultly soluble in 

 cold water, easily soluble in hot water, in alcohol and 

 ether; fuses at 182, and when heated to a higher 

 temperature it is resolved into water and phtalic anhy- 

 dride, C 8 H 4 3 , a substance that crystallizes in long 

 lustrous needles; fusing point, 127-128. Heated 



