36 
ON AGrUA-REGIA. 
When gold is acted upon by aqua-regia, the nitric oxide in 
the mixture is reduced to somewhat less than 1 equivalent. 
These facts, and the different relative proportions of the two 
gases obtained from successive portions of the liquid, show 
that the body is a mixture, and that N0 2 Cl 2 is not the only 
constituent of the chloronitric liquid. There is at least one li- 
quid in the condensed products from aqua-regia possessing 
the composition shown by the formula — 
N0 2 CI, 
which latter may also be obtained directly by allowing ni- 
tric oxide and chlorine to condense together in a vessel 
surrounded by a cooling-mixture ; but even then the pro- 
duct is not a definite body, for the proportions of nitric oxide 
gas in the less volatile portions are very much greater than 
in the more volatile. The same results were obtained from 
the vapour of the liquid condensed from a mixture of com- 
mon salt with nitric acid. 
These condensed liquids, prepared in different manners, 
are, therefore, mixtures in variable proportions of the two 
compounds, NO2 CU, and N0 2 CI. 
The products bear a great analogy to the hyponitric and 
nitrous acids, and it is proposed to call them hypochloroni- 
tric acid and chloronitrous acid respectively. They are 
both decomposed immediately by water, and give rise to 
hydrochloric acid and the products of hyponitric acid. 
Aqua-regia, therefore, whether concentrated or diluted, 
without the agency of any other body, and simply under the 
influence of heat, is decomposed into chloronitric vapour, 
chlorine and water. 
When gold is acted upon by aqua-regia, the author's ex- 
periments tend to show that the products of decomposition 
are precisely the same, the chlorine only being retained by 
the gold, and the chloronitric vapour, to which the action of 
aqua-regia upon gold has been erroneously attributed, pass- 
ing off as if no gold were concerned in the reaction. — Quar- 
terly Journal of the Chemical Society. 
