ACTION OF NITRIC ACID UrON AMIDINE. 
63 
peared in the nitric acid. Since an excess of this acid con- 
verts the xyloi'dine into a very soluble matter, which is 
nothing else than the new acid indicated above; this, like- 
wise explains the different result obtained by M. Bracconot, 
who procured a weight of xyloi'dine equal to the weight of 
the amidine employed. This is evidently owing to the fact 
that part of the former substance had been already decom- 
posed. By delaying still more the precipitation, he would 
soon have been convinced of the impossibility of obtaining 
the slightest trace of xyloi'dine. 
When, instead of setting aside at ordinary temperatures, 
the mixture of amidine and concentrated nitric acid, the mix- 
ture is caused to boil, the amidine is decomposed in a few 
minutes, and converted into a deliquescent acid, which may 
be easily obtained pure, and in large quantity, by evaporation 
on a salt water bath. This acid does not contain azote; it has 
some resemblance to oxalhydric acid, but differs in its com- 
position. A moderate heat converts it into another acid of a 
black color, soluble in water, and capable of reproducing, 
under the action of nitric acid, the white acid from which it 
is derived. 
Boiling concentrated nitric acid attacks it with great 
difficulty. In the cold, it changes it slowly into oxalic acid, 
without any production of carbonic acid. Thus, by slow 
oxidation, determined by the presence of a suitable quantity 
of concentrated nitric acid, the amidine is changed successively 
into xyloi'dine, a deliquescent acid, and into oxalic acid, with- 
out the carbon participating in the displacement of the other 
elements of these matters. These curious reactions take place 
of themselves in closed vessels. 
We have said that the xyloi'dine results from the combina- 
tion of amidine with the elements of nitric acid. It is a salt 
in which amidine fulfils in relation to the nitric acid the part 
of a base; thus, it is very combustible at the temperature of 
180° c. It takes fire, consumes without residue, and with 
much quickness. This property has led to an experiment 
which may be susceptible of some applications, especially in 
