26 COMBINATIONS OF OXALIC ACID. 



Superoxalate of soda, 



5?uperoxaiate '^^^ supcroxalate of soda is less soluble than the neutral 

 of soda. oxalate. It may be obtained by direct combination of the 



oxalic acid with Boda, or by the action of oxalic acid wn mu- 

 riate of soda. 



10 gr. of this salt, urged in the fire, yielded 4*09 gr. of 

 subcarbonate of soda — 2'557 gr* of soda. 



10 gr. of the same salt, precipitated by muriate of lime, 

 yielded 1 1*741 of oxalate of lime zz 7*28 gr. of oxalic acid. 

 The proportions of this salt therefore are 



Ifs component 25*57 soda, 



^"*' 72-80 oxalic acid, 



1-63 water. 



100. 



And 100 parts of soda are combined in it with 284'7 of 

 acid. 

 Its acid double It appears by the proportions I have given, that in the 

 alate. °^' ^^^^ oxalate of soda the base is combined with twice as 

 much acid as in the neutral oxalate, analogous to what occurs 

 with potash. In confirmation of this, I urged in the fire 10 

 gr. of superoxalate of soda; and the alkali, resulting from 

 its decomposition, was sufficient exactly to neutralize 10 gr. 

 of the same superoxalate, 

 Ifoquadroxa- \ tiled in several ways to combine soda with a larger 

 quantity of acid, but I could not succeed; so that I believe 

 no quadroxalate of soda exists. 



Oxalate of ammonia. 



Oxalate of am- ^''- Berthollet has ascertained by very accurate experi- 

 raonia. nients, that a solution of ammonia of the specific gravity of 



09656 contains 8*761 of real ammonia in JO©, Adopting 

 this datum, the most convenient method of determining the 

 proportions of the compound of ammoiaia with oxalic acid 

 appeared to me to be, to find the quantity of this ammonia 

 necessary to neutralize a given weight of oxalic acid. 



5 gr. of crystallized oxalic acid required for their neu- 

 tralization 9*5 of ammonia of the spec. grav. abovemention- 



ed, 



