184 BACEMIC ACID. 



on cooled ethyl tartrate. The former is a colorless oil, 

 not volatile without decomposition ; the latter forms 

 large clear crystals, which fuse at 67 and boil at 288- 

 290 without undergoing decomposition, and can be 

 crystallized from boiling water. 



Nitrotartaric acid, COT(Q jjjj) { gj'g When 



finely pulverized tartaric acid is dissolved in very con- 

 centrated nitric acid, and concentrated sulphuric acid 

 gradually added to the solution, there is formed a pasty 

 mass, which, when pressed between porous stones, 

 leaves behind a white shiny mass of nitrotartaric acid. 

 This is soluble in water, but the solution decomposes 

 very rapidly, and yields tartronic acid (p. 176) by spon- 

 taneous evaporation. 



Ethyl nitrotartrate, C 2 H 2 (O.K0 2 ) 2 (CO.O.C 2 H 5 ) 2 . 

 Is produced when ethyl tartrate and a mixture of con- 

 centrated nitric and sulphuric acids are brought to- 

 gether. Colorless prisms ; fusing point, 45-46. 



The following acid is isomeric with and very similar 

 to tartaric acid : 



2. Racemic Acid. 

 C 4 H 6 8 . 



This occurs, together with tartaric acid, in a number 

 of varieties of grapes. It can be prepared artificially by 

 heating cinchonin tartrate to 170 ; by oxidizing several 

 of the carbohydrates. The acid formed from dibrom- 

 suecinic acid with water and silver oxide appears to be 

 racemic acid. It forms clear, rhombic prisms with 1 

 molecule of water of crystallization, which is given off 

 at 100. It is less soluble in water than tartaric acid. 

 At an elevated temperature and towards reagents, it 

 conducts itself almost precisely like the latter. It 

 causes, however, a precipitate in a solution of calcium 

 chloride and even of gypsum, whereas free tartaric 

 acid does not precipitate these solutions. Precipitated 



