104 Dt. Thomas Thomson [Aug. 



reddens litmus paper. If we reverse this process by pouring 

 carbonate of ammonia into a solution of racemic acid, bi-ra- 

 cemate of ammonia soon appears and renders the neutraliza- 

 tion of the acid tedious. When the concentrated solution 

 of racemate of ammonia is set aside, beautiful crystals are 

 deposited. 



The crystals are long four-sided prisms, terminated by two 

 faces applied to each other like the roof of a house. The 

 primary form seems to be a doubly oblique four-sided prism ; 

 the sides being inclined at an angle of 94*45°. When 

 these crystals are exposed to the air they effloresce lightly, 

 and assume a silky lustre. In that state their specific 

 gravity is 1*639. 



When the salt is distilled it does not melt, but gives off 

 water and speedily acquires a dark colour. A black bulky 

 charcoal remains after the process, and a dark brown liquid 

 passes over, having an empyreumatic smell, and the receiver 

 is filled with fumes of ammonia. Feather-shaped crystals 

 of carbonate of ammonia are gradually deposited in the 

 beak of the retort. 



The taste of racemate of ammonia is saline, but it leaves 

 a disagreeable impression in the mouth, somewhat like that 

 of nitre. At the temperature of 60° 100 parts of water 

 dissolve 14*58 parts of the effloresced crystals. The solu- 

 bility increases with the temperature. The salt is scarcely, 

 if at all, soluble in absolute alcohol. 



To determine the constituents of this salt, 107 grs. of the 

 crystals of racemic acid, which have been shown above to be 

 equivalent to 82*5 grs. of real acid, were saturated with 

 carbonate of ammonia, and the liquid evaporated to dry- 

 ness in a gentle heat. The silky crystals obtained were 

 neutral, and weighed 111 grs. Now, 82*5 grs. of racemic 

 acid require for neutralization 21*25 grs. of ammonia. 



Consequently, the salt was composed of, 



Racemic acid . . . 82*5 or 8*25 



Ammonia 21*25,, 2*125 



Water 7*25 „ 0*725 



111*00 

 0*725 exceeds the weight of half an atom of water by 0*1525, 

 or about |th of an atom. This smajl excess is, doubtless, 



