1904. J KELLER AND MA AS — DIMETHYL RACEMIC ACID. Ill 



an intermediate product in the preparation of pure dimethyl 

 racemic acid. Its formation and properties have been described by 

 Fittig and Keller, who were unable, however, to spare any of their 

 material for analysis. 



A carefully prepared specimen afforded the following determi- 

 nations : 



Required. Found. 



H^O 8.59% 8.52% 



Pb 49.40" 49.22<« 



The copper salt is anhydrous. When a solution of copper acetate 

 is added to a soluble dimethyl racemate, the liquid remains per- 

 fectly clear, but on acidifying it with acetic acid, a light green 

 amorphous precipitate is produced. It is probable, therefore, that 

 this copper compound when first formed exists in the colloidal state. 

 The weight of the air-dry salt remained constant on heating; 



it yielded — 



Calculated. Found. 



Cu , 26.39 % 26.49 % 



Silver salt. A voluminous and amorphous precipitate, which 

 becomes denser on standing and darkens when exposed to light, 

 results upon addition of silver nitrate to a neutral solution of the 

 sodium salt. It is likewise anhydrous. 



Calculated. Found. 



Ag 55-io% 54.76% and 54.92% 



When we compare the above results with the composition and 

 properties of the corresponding tartrates, and more particularly the 

 racemates, we are forced to admit that the acid obtained from dia- 

 cetyl bears the closest resemblance to the group of isomeric com- 

 pounds, of which it is the dimethyl derivative. Such differences 

 as have been observed between dimethyl racemates and racemates 

 are no greater (if indeed as great) than those known to exist 

 among the salts of the several modifications of tartaric acid. 



Action of Heat upon Dimethyl Racemic Acid. — It was noticed by 

 Fittig and Keller that when the acid is heated to* 178°-! 79° it 

 melts with partial decomposition, and is completely volatilized, 

 without charring, when the temperature is raised sufficiently. 



Experiments, which have thus far been made on a small scale 

 only, indicate the presence of at least one, arid probably of two 



