374 Dr. J. L. Smith on Actions of Nitric and Oxalic Acids. 
is well known that if nitric acid be added to a chlorid, or hy- 
drochloric acid to a nitrate, more or less of a decomposition will 
in either case ensue ; but I believe it is not generally known how 
ready and complete the replacement is, when nitric acid is heated 
with chlorid of potassium or of sodium. 
Among the experiments made, 40 grammes of nitric acid were 
boiled gently with 6 grammes of chiorid of potassium, and i 
twenty minutes, no trace of chlorine could be found in the liquid ; 
the same is true when the chlorid of sodium is used. The opera- 
tions appear to depend on the oxydizing property of the nitric acid, 
with the liberation gf chlorine that combines with some of the ele- 
ments of nitric acid to form the chloronitric acid that readily passes 
off. 'The decomposition of the nitrates of the alkalies by hydro- 
chlorie acid does not readily takes place, it not being complete 
even after repeated evaporations to dryness, with a large excess 
of hydrochloric acid. 
2. Before setling on the plan I now adopt, an easy method was 
sought for separating the alkalies from magnesia, by converting 
the two into carbonates,—a plan that had previously been adopted ; 
but the question with me was to change the nitrates to carbon- 
ates. The idea suggested itself of heating the nitrates with an ex- 
cess of oxalic acid, to the temperature at whic the latter undergoes 
decomposition, w when the nascent oxyd of carbon might break up 
the constitution of - nitric acid, and the carbonic acid formed 
combine with the 
On making the a pa iiont I was surprised to see an abundant 
evolution of nitrous acid vapors at a temperature considerably be- 
low 212°. It was clear that the oxalic acid decomposed the ni- 
trate, liberating the nitric acid, which reacting on the excess 0 
oxalic acid, gave rise to the nitrous acid vapors. If crystallized 
oxalic acid ‘aud 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 nl- 
trous acid and carbonic acid ; at 212° the evolution is vigorous, 
and if after evaporation to dryness t the water be renewed several 
times, the nitric acid will be completely expelled from the nitre, 
there a 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 chlorids of the alkalies, and on 
experiment, the conclusion proved to be correct. If an excess ° 
oxalic acid be mixed with either the chlorid of potassium oF of 
sodium, and the whole warmed gently, abundant vapors of hydro- 
chloric acid are evolved, and i careful manipulation, all the 
chlorine may be driven off under this form. 
t 
