OXALIC ACID. 103 



Oxalic acid 4-5 = 1 atom 



Water . . 4*5 = 4 atoms 



9 



Thus, the crystals contain just half their weight 

 of water, as was pointed out long ago by Vau- 

 quelin.* 



* Understanding that a chemical friend, of whose accuracy and iiiforma 

 tion I entertain a very liigli opinion, had stated, that the uniform result of 

 his experiments was, that the crystals of oxalic acid contain only 3 atoms 

 of water instead of 4-, and that they are composed of 



1 atom anhydrous acid . . 4-5 

 3 atoms water . . . 3-375 



7-875 



I was induced to repeat the experiments in the text with every possible at- 

 tention to accuracy, and to extend them a good deal farther. It may be 

 proper to state here the result of these new experiments. 



1. 18 ( = 9 X 2 ) grains of the crystals of oxalic acid were dissolved 

 in water, supersaturated with ammonia, the solution evaporated to drynqss 

 in a gentle heat, and the oxalate of ammonia left redissolved in water. 

 13-5 grains of very pure calcareous spar were dissolved in nitric acid, the 

 solution evaporated to dryness, and the residual salt being heated suffi- 

 ciently to drive off any excess of acid which it contained, was redissolved 

 in water. These two solutions were mixed together, and after the oxalate 

 of lime had subsided, the clear liquid was tested with muriate of lime and 

 oxalate of ammonia, but was not affected by either, showing that it con- 

 tained neither lime nor oxalic acid. This experiment agrees with the one 

 stated in the text ; the only difference being the substitution of nitric acid 

 for muriatic acid to dissolve the lime. It shows, that the oxalic acid in 9 

 grains of the crystals just saturates 3-5 grains of lime, which is equivalent 

 to an atom. 



2. The preceding experiment was repeated, with this difference, that, in- 

 stead of 9 grains of oxalic acid I substituted 8-875 grains of the crystals of 

 oxalate of ammonia : the result was the same as before the residual liquid 

 was neither affected by oxalate of ammonia nor muriate of lime. Tliis ex- 

 periment shows, that 8-875 grains of oxalate of ammonia and 9 grains of 

 oxalic acid crystals, contain the same weight of real oxalic acid. 



G4 



