BENZOIC ACID. 331 



of manganese being gradually added, and the evapo- 

 rated water being replaced, until the color of the mass 

 has become bright yellow. This is then dissolved in 

 water, the solution neutralized with sulphuric acid, 

 filtered, evaporated to dryness, and the sodium anthra- 

 nilate extracted by means of alcohol. The salt that 

 remains behind after the evaporation of the alcohol 

 is then dissolved in water and decomposed by acetic 

 acid. It is also formed by the action of sodium-amal- 

 gam on the bromamidobenzoic acids (obtained by re- 

 duction of the two bromnitrobenzoic acids). Thin, 

 colorless prisms or laminse, but slightly soluble in cold 

 water, easily in hot water and in alcohol. Fuses at 

 144, and decomposes at a higher temperature, yield- 

 ing anilin and carbonic anhydride. 



Meta-amidobenzoic acid is formed by heating 

 an alcoholic solution of metanitrobenzoic acid with 

 ammonium sulphide, and decomposing the ammonium 

 salt thus obtained with acetic acid. Is obtained more 

 readily by gently heating metanitrobenzoic acid with 

 tin and concentrated hydrochloric acid. After the ac- 

 tion is over the solution is precipitated with an excess 

 of sodium carbonate, and the concentrated solution 

 acidified with acetic acid. Small, colorless prisms, 

 easily soluble in hot water, slightly in cold. Fuses at 

 164-165; and is resolved, by heating with caustic 

 potassa, into carbonic anhydride and anilin. Yields 

 crystallizing salts with bases, as well as with acids. 



Para-amidobenzoic acid (Amidodracylic acid) is 

 obtained from paranitrobenzoic acid in the same way 

 as the meta-acid. Long, fine, lustrous needles. Fusing 

 point, 186-187 ; moderately easily soluble in water. 



Diamidobenzoic acid, C 6 H 3 (ira 2 ) 2 .CO.OH. Is ob- 

 tained from dinitrobenzoic acid by reduction with tin 

 and hydrochloric acid. Almost colorless, long, thin 

 needles ; fusing point, 240 ; not volatile without de- 

 composition. Difficultly soluble in cold water ; com- 

 bines with bases and acids, forming salts. 



