ACTIONS OF NITRIC AND OXALIC ACIDS. 257 



been adopted; but the question with me was to change the 

 nitrates to carbonates. The idea suggested itself of heating 

 the nitrates with an excess of oxalic acid to the temperature 

 at which the latter undergoes decomposition, when the nascent 

 oxide of carbon might break up the constitution of the nitric 

 acid, and the carbonic acid formed combine with the bases. 



On making the experiment I was surprised to see an abundant 

 evolution of nitrous-acid vapors at a temperature considerably 

 below 212°. It was clear that the oxalic acid decomposed the 

 nitrate, liberating the nitric acid, which reacting on the excess 

 of oxalic acid gave rise to the nitrous- acid vapors. If crystal- 

 lized oxalic acid and the nitrate of potash or soda, the former 

 in excess, be placed together in a flask and heated over a 

 water-bath, the mass soon enters into watery fusion, and at the 

 temperature of from 130° to 140° bubbles of gas are evolved, 

 consisting of nitrous acid and carbonic acid. At 212° the 

 evolution is vigorous; and if after evaporation to dryness the 

 water be renewed several times, the nitric acid will be com- 

 pletely expelled from the niter, there remaining the excess 

 of oxalic acid and the oxalate of the alkalies. 



It was natural to conclude from the above result that oxalic 

 acid would likewise decompose the chlorides of the alkalies, 

 and on experiment the conclusion proved to be correct. If an 

 excess of oxalic acid be mixed with either the chloride of po- 

 tassium or of sodium, and the whole warmed gently, abundant 

 vapors of hydrochloric acid are evolved, and by careful manipu- 

 lation all the chlorine may be driven off under this form. 



If heat be applied to the mass resulting from the action 

 of oxalic acid on either the nitrates or the chlorides, all the 

 oxalic acid will be expelled and the oxalates converted into 

 carbonates. A small amount of chloride of sodium can in this 

 way be converted in a few moments into carbonate of soda ; 

 not, however, without some trace of the chloride being present. 

 It is not my object to point to any special application of this 

 decomposition, but it is one that may come into play in certain 

 operations in analytical chemistry. 



Experiments were made with the sulphates of the alkalies 

 to see if the oxalic acid had any decomposing action on them, 

 expecting to test for free sulphuric acid by the action of the 

 solution of the mass on zinc or iron, taking for granted that 



