PYRORACEMIC ACID. 175 



Decompositions. The pure acid heated to 140 is 

 converted into a brownish mass, resembling gum arabic ; 

 it absorbs water with avidity and breaks up at a higher 

 temperature into water and pyroracemic acid. Pyro- 

 tartaric acid and pyrotartaric anhydride are formed as 

 secondary products in this reaction. By boiling gly eerie 

 acid with potassa, oxalic and lactic acids are produced ; 

 fusing caustic potassa resolves it into acetic and formic 

 acids. Hydriodic acid (phosphorus iodide and water) 

 converts it into iodopropionic acid (p. 91). By the 

 action of phosphorus chloride on the free acid or the 

 lead salt, j3-chlorpropionyl chloride (p. 90) is formed. 



Serine (Glyceramic acid, amidolactic acid), C 3 H 7 

 T0 3 = C 2 H 3 1 2 1 CO.OH, is formed when glue is 



boiled with dilute sulphuric acid. Hard, brittle crys- 

 tals ; easily soluble in hot water, more difficultly in 

 cold (in 32 parts at 10), insoluble in alcohol and ether. 

 Combines with acids and bases ; yields glyceric acid, 

 when treated with nitrous acid. 



Cystine, C 3 H 7 N0 2 S probably = C 2 H 3 | ^ 2 JCO. 



OH. As yet, only found in urinary calculi of rare 

 occurrence, and in urinary sediments. As a stone, it 

 is of a dirty yellowish color, translucent, crystalline. 

 In a pure condition, crystallizing in colorless, transpa- 

 rent laminae, insoluble in water, easily soluble in acids 

 and alkalies. From a solution in hot aqueous potassa, 

 it crystallizes slowly on the addition of acetic acid. 



Pyroracemic acid (pyruvic acid), C 3 H 4 3 = CH 3 . 

 CO.CO.OH, is produced by the dry distillation of tar- 

 taric and glyceric acids. Liquid, boiling at 165-170, 

 suffers partial decomposition, however, when distilled, 

 carbonic anhydride and pyrotartaric acid being formed. 

 Monobasic acid. Gives crystallizing salts, which are 

 changed when their solutions are heated. Nascent 

 hydrogen converts it into lactic acid. On boiling it 



