BENZOIC ACID. 141 



very different properties ; but this difficult sub- 

 ject stands in need of farther investigation. 



3. Succinic acid furnishes a very easy method 

 of separating iron from other bodies with which 

 it is mixed in acid solutions, and determining its 

 quantity a method proposed many years ago 

 by M. Gehlen. The method is this : Peroxi-. 

 dize the iron in the solution by digesting it with 

 some nitric acid. Then make the solution as 

 neutral as possible by means of ammonia. Suc- 

 cinate of ammonia will now precipitate the iron 

 in red coloured flocks. Separate the precipitate 

 upon a double filter, wash it well, and dry it in 

 the temperature of 212; |ths of the weight of 

 this precipitate is peroxide of iron, and the re- 

 maining fths are succinic acid. 



SECT. VI. 



OF THE ATOMIC WEIGHT OF BENZOIC ACID. 



THIS acid, like the preceding, is obtained by 

 sublimation, and its crystals, like those of suc- 

 cinic acid, are free from water. There is there- 

 fore little difficulty in determining its atomic 

 weight. 



1. Fifteen grains of the crystals were dissolved we . wht 

 in distilled water by means of ammonia, and the benzole 

 solution was concentrated on the sand bath till 



9 



