1835.] on Racemic Acid. 105 



lodged mechanically in the plates of the crystals. The 

 chemical constituents of racemate of ammonia are obviously 

 1 atom acid .... 8*25 

 1 ,, ammonia . . 2*125 

 J ,, water . . . 0*5625 



10-9375 



When ammonia or its carbonate is cautiously dropt into 

 a solution of racemic acid, bi-racemate of ammonia falls in 

 bulky flocks, consisting of minute crystals. It resembles 

 bi-tartrate of ammonia closely, both in its appearance and 

 solubility in water. ' 



Tartrate of Ammonia. 



This salt may be formed precisely in the same way as the 

 racemate, only substituting tartaric for racemic acid. 



Its taste is sa],ine, and very similar to that of sal-ammo- 

 niac. It usually forms small gritty crystals. But it may be 

 obtained in large transparent, four-sided, rectangular prisms, 

 terminated by a face inclined at angles of 120° and 60°, to 

 the two opposite faces of the prism. In general all the 

 edges of the prism are replaced by tangent planes, making 

 an eight-sided prism, with angles of 135°. 



At 55° 100 water dissolve 60*03 parts of these crystals, 

 so that it is at least four times as soluble in water as race- 

 mate of ammonia. 



Its constituents, determined in the same way as those of 

 racemate of ammonia, were found to be, 



1 atom tartaric acid . . 8*25 

 1 ,, ammonia . . . 2*125 

 1 ,, water .... 1*125 



11*5 

 Thus it differs from racemate of ammonia in the shape of 



its crystals, in its solubility in water, and in the water of 



crystallization being twice as great. 



When heated it smokes, becomes brown and swells up 



like a burning feather, without flaming, leaving a coal 



which burns very slowly but completely, without leaving 



any residue. 



