420 KC@NE ON THE NATURE OF AQUA REGIA, 
Soon after, water weakens the affinities to such a degree that 
the reaction would cease if we were not to employ a metal of 
the sixth division, for instance, gold. 
19. These phenomena show that the formation of the agua 
regia by no means results from a reciprocal action between the 
elements of the hydrochloric and nitric acids (the latter con- 
sidered according to the formula NO‘ + O), but it originates from 
the action of the hydrogen of the one on the oxygen of the 
other. In fact, for the action to occur, it is requisite that either 
heat, or a body having affinity for chlorine, or both at the same 
time, diminish the affinity of the chlorine for the hydrogen of 
the hydrochloric acid, and increase that of the same chlorine 
for the hydrogen of the water, so that the dehydrating effect of 
the nitric acid is rendered more powerful. 
Now if the reaction took place under the influence of a double 
affinity (7.) these phenomena would not occur, the chlorine would 
not be disengaged or enter into a combination precisely when 
formed with the hyponitric acid. 
In making these observations, we have by no means left out 
of consideration the various circumstances in which a chemical 
action occurs at the very moment when the affinities which 
called it into existence are annihilated. We have even placed 
the hypothesis which considers the hyponitric acid as a radical 
at the head of these observations, and we have endeavoured to 
support it by allowing gaseous hydrochloric acid to act upon 
concentrated nitric acid at a low temperature, and protected from 
the influence of water, but instead of obtaining the compound 
NO?‘ + Cl, we observed and showed that these acids are re- 
duced to water, chlorine and nitrous acid (11, 12, 14). These 
then are the products which the active agua regia yields. With 
respect to the causes from which they proceed, these may be— 
1, the tendency of the chlorine to assume the gaseous state, or 
to combine with the metal; 2, the slight stability of the nitric 
acid, and its dehydrating power; 3, the tendency of the nitrous 
acid to escape or to enter into combination*. 
* M. Baudrimont states that he obtained a peculiar gas on acting with com- 
mercial hydrochloric acid upon nitric acid at a temperature of 86°C. This 
gas, which he regards as the active principle of agua regia, would correspond 
to nitric acid, and be represented by the formula NO® Cl?. 
I know not whether M. Baudrimont has allowed himself to be guided by the 
hypothesis of E. Davy, according to which the product of nitric acid on fused 
chloride of sodium is the active principle of agua regia; but so much is certain, 
that if the chlorazotic acid exists, it must possess very peculiar properties, 
