1835.] en Racemic Acid, 167 



The heat being raised to 326°, and continued for three hours 

 longer, the weight of the salt was reduced to 13*85 grs., but 

 the salt was discoloured. This residue being burned, left 

 7*5 grs. of carbonate of lime, equivalent to 4*2 grs. of lime. 

 This being precisely the same result as with racemate of 

 lime, it is clear that the composition of both must be the 

 same. 



VIII. — RACEMATE OF MAGNESIA. 



Racemic acid does not occasion a precipitate when dropt 

 into a solution of sulphate of magnesia ; neither is any pre- 

 cipitate produced by racemate of soda. But if we mix solu- 

 tions of racemate of soda and sulphate of magnesia in the 

 atomic proportions, evaporate the liquid to dryness, and 

 then digest the dry residue in water, a white residue re- 

 mains, which IS racemate of magnesia. 



It is tasteless, has a sp. gr. of 1*980, and at the tempera- 

 ture of 64°, 100 parts of water dissolve 0*35 parts of it. 



Magnesia alba dissolves easily in an excess of racemic 

 acid in water, when the action is assisted by heat. When 

 this solution is concentrated, racemate of magnesia is depo- 

 sited in crystalline crusts. It is difficult to free these crusts 

 from all excess of acid. After repeated washings they still 

 reddened litmus paper. But the addition of a very minute 

 quantity of ammonia rendered them alkaline. It is clear, 

 from this, that the salt was a simple racemate, with a very 

 slight excess of acid. 



10 grs. of the racemate, formed by double decomposition, 

 when heated to redness, burned like tinder, and left 1*95 grs. 

 of magnesia. The salt being neutral, must have been com- 

 posed of Magnesia . . 1950 or 2*5 



Racemic acid 6*435 ,, 8*25 

 Water . . . 1*615 „ 2*07 



10*000 

 The water is rather less than 2 atoms, probably because 

 the salt had been dried by artificial heat. 



The sp. gr. of the racemate obtained by dissolving mag- 

 nesia alba in racemic acid, was only 1*32. It was a com- 

 pound of 1 atom racemic acid . 8*25 

 1 atom magnesia . . 2*5 

 ^ 4i atoms water . . . 5* 0025 



15-7525 



