408 
DR. BENCE JONES ON THE OXIDATION OF 
were passed through dilute carbonate of potash ; after an hour no trace of nitric acid 
could be detected. 
The experiment was repeated with a brisker fire, and a trace of nitric acid was 
found. 
By the combustion of a wax candle, a slight trace of nitric acid was detected after 
it had burnt one hour. 
The product of the combustion of ordinary coal-gas gave plenty of nitric acid. To 
purify it from ammonia, it was passed through dilute sulphuric acid; nitric acid in 
much smaller quantity than before was then detected. 
This experiment was repeated, passing the coal-gas through a tube 3 feet long, full 
of asbestos and pumice-stone moistened with strong sulphuric acid, and then through 
a thin layer of strong sulphuric acid. After combustion for an hour, nitric acid was 
detected by all the tests. When the laboratory air was passed for an hour through 
the same solution of carbonate of potash, no trace of nitric acid could be detected. 
When the atmospheric air, as well as the coal-gas, were first passed through tubes 
containing sulphuric acid, and afterwards burnt for one hour, nitric acid was detected 
among the products of combustion, by the starch and by the indigo test. 
If instead of depriving the gas of ammonia it was made to pass over the vapour of 
ammonia and then burnt, nitric acid could be detected by the starch test with 
the greatest certainty after two minutes’ combustion ; but with the same flame, after 
six hours’ combustion, I was unable to obtain any very considerable quantity of 
nitrate of potash. 
These experiments on the production of nitric acid in all cases of combustion 
in the air, render it very probable that small quantities of nitric acid exist always in 
the atmosphere, and that nitric acid will be constantly detected in rain and snow, 
not only after a thunder-storm, but at all other times also. At least, by adding 
pure carbonate of potash to rain-water, and evaporating it to a very small bulk, I 
have succeeded in detecting nitric acid in the water which fell in London, on a con- 
tinuously rainy day in December. Fourteen pints, when evaporated to two ounces, 
furnished positive proof of the presence of nitric acid by the indigo, starch and iron 
tests. 
On another day ten pints, evaporated to a very small bulk, gave evidence of nitric 
acid. 
Should nitric acid be found to be present in the air at all times and in all places, 
its importance to the growth of plants will not be less than that of the ammonia 
which has been detected there. 
Thus, whether in the body or out of the body, the oxidation of ammonia gives rise 
to a combination of oxygen with nitrogen. Nitrous and nitric acids are produced. 
It is very difficult to determine the quantity of these acids formed in the body, but 
the experiments mentioned above prove that some portion of the nitrogen is oxidized 
in the passage of ammonia through the system. 
