ACETIC ACID. 83 



time on a water-bath, the ether precipitated with water 

 and purified by means of distillation. Colorless liquid, 

 boiling at 143.5, but slightly soluble in water. 



Dichloracetic acid, C 2 H 2 C1 2 2 = CHCP.CO.OH, is 

 formed by the further action of chlorine on monochlor- 

 acetic acid in the presence of iodine. A liquid, boil- 

 ing at 195, forming, when perfectly pure, rhombohe- 

 dral crystals. 



Ethyl dichloracetate, C 2 HC1 2 O.O.C 2 H 5 , is obtained 

 by conducting dried hydrochloric acid gas into a solu- 

 tion of the acid in absolute alcohol ; is also formed by 

 heating carbon chloride, C 2 C1 4 , with sodium ethylate. 

 Heavy liquid, boiling at 153-158. Is decomposed when 

 kept for any length of time, or when agitated with caus- 

 tic soda, forming oxalic acid and hydrochloric acid. 



Trichloracetic acid, C^CPO 2 , is formed by the 

 action of an excess of chlorine on acetic acid in direct 

 sunlight ; by the decomposition of trichloracetyl chloride 

 by water, and by the action of chlorine in direct sun- 

 light on carbon chloride, C 2 C1 4 , in presence of water ; 

 and is prepared most readily by the oxidation of chloral 

 with fuming nitric acid. Colorless, rhombohedral crys- 

 tals, deliquescent; fuses at 46; -boils at 195-200. 

 Combines with bases forming crystalline salts. When 

 boiled with ammonia, it is resolved into chloro- 

 form and potassium carbonate, potassium formate, and 

 potassium chloride. 



Mono- and Dibromacetic acids, C 2 H 3 Br0 2 and 

 C 2 H 2 Br 2 2 , are formed when acetic acid or acetic ether 

 is heated with bromine in sealed tubes at 180. Mono- 

 bromacetic acid forms deliquescent rhombohedral crys- 

 tals, and boils at 208 ; dibromacetic acid, a crystalline 

 mass, fusing at 45-50 and boiling at 232-234. The 

 salts of both acids are somewhat unstable. Ethyl mono- 

 bromacetate is a colorless liquid, boiling at 159 with 

 partial decomposition. Its vapor attacks the eyes vio- 

 lently. Tribromacetic acid, C^Bi^O 2 , results by the 



