1835.] on Racemic Acid. 99 



temperature the crystals of tartaric acid undergo no change 

 and lose no weight. When the heat is increased, racemic 

 acid undergoes no further change till it reach the tempera- 

 ture of 370°, when it becomes yellow at the bottom, be- 

 ginning to undergo decomposition. At 250° tartaric acid 

 liquifies and loses about 4 per cent, of its weight. The liquid 

 is transparent. On cooling it becomes solid and resembles 

 a piece of crystal glass. Thus altered it slowly imbibes 

 moisture from the atmosphere and runs into a liquid. 



At the temperature of 49°, 100 parts of water dissolve 

 14*1 of racemic acid crystals. At the same temperature 

 100 parts of water dissolve 64*8 of tartaric acid. Thus at 

 the temperature of 49°, tartaric acid is about 4 J times more 

 soluble than racemic acid. 



At the temperature of 1 ip° 1 00 parts of water dissolve 

 37*94 of racemic acid and 80-48 of tartaric acid. These 

 facts shew that tartaric acid is much more soluble in water 

 than racemic acid. 



Racemic acid may be used as well as tartaric acid to 

 prevent a solution of antimony in muriatic acid from being 

 precipitated when diluted with water. In this property the 

 two acids agree, proving that racemic acid has the same 

 tendency to enter into triple combinations as tartaric acid. 



A striking difference between tartaric and racemic acid 

 is exhibited when we drop solutions of these acids into 

 chloride of calcium dissolved in water. The former occa- 

 sions no precipitate, while the latter throws^down a copious 

 deposit. Thus, we see that racemic is a more powerful acid 

 than tartaric. Accordingly, it is capable of decomposing 

 various tartrates and taking the place of the acid. 



Atomic weight of Racemic Acid. 



The following experiments were made in order to deter- 

 mine the atomic weight of this acid. Some trials made in 

 the year 1827 in my laboratory by a very ingenious pupil, 

 had led me to infer that 8*5 represented the atomic weight, 

 but they were not of such a nature as to decide the point. 

 Those that I shall now relate were made by myself with 

 every attention to accuracy. 



1 . One hundred and seven grains of crystals of racemic 

 acid were triturated in a mortar and exposed for 24 hours in 



h2 



