84 ACETIC ACID. 



action of water on tribromacetyl bromide (which see). 

 Crystals, which fuse at 130, and boil at 245. 



lo do acetic acid, C 2 H 3 I0 2 . Is produced when a 

 mixture of acetic anhydride, iodine, and iodic acid is 

 heated to boiling (140), a violent reaction taking 

 place. Ethyl bromacetate is decomposed by potassium 

 iodide, forming potassium bromide and ethyl iodoace- 

 tate, and this, when heated with baryta water, gives 

 barium iodoacetate, which, treated with sulphuric acid, 

 yields the acid. Colorless plates, which fuse at 82 

 with partial decomposition. When heated with hydri- 

 odic acid, it is reconverted into acetic acid. Most of 

 its salts are decomposed, when merely boiled with 

 water. Diiodoacetic acid, C 2 H 2 I 2 2 , is obtained in a 

 similar manner. 



Cyanacetic acid, C 3 H 3 N0 2 = CH 2 (ON"),CO.OH. 

 Monochloracetic acid (5 parts) is boiled with potassium 

 cyanide (6 parts) and water (24 parts) until the smell 

 of prussic acid can no longer be detected ; the liquid is 

 then neutralized exactly with sulphuric acid, evaporated 

 down to a small volume, filtered, supersaturated with 

 sulphuric acid, and by agitating with ether the cyan- 

 acetic acid extracted. The crude acid, that remains 

 behind after the evaporation of the ether, can be puri- 

 fied by conversion into its lead salt and decomposition 

 of this with sulphuretted hydrogen. Colorless, crys- 

 talline mass. Its salts, with the exception of the silver 

 and mercury salts, are easily soluble in water. 



Amido acetic acid (G-lycin, Glycocol), C 2 H 5 N0 2 = 

 CH 2 N"H 2 )CO.OH. Is produced from chlor- and brom- 

 acetic acids by heating with ammonia. Hippuric acid 

 (which see), when boiled with acids or alkalies, is re- 

 solved into glycocol and benzoic acid. Glycocholic acid 

 (which see), treated in the same manner, }delds glycocol 

 and cholic acid. It is produced further by boiling 

 glue with sulphuric acid or potassa. It is prepared 

 most practicably by boiling hippuric acid for an hour 

 with four times its weight of concentrated hydrochloric 



