AMMONIA IN THE HUMAN BODY. 
409 
The importance of this oxidizing' action in effecting a change in the injurious sub- 
stances which happen to be present in the blood, cannot be overlooked, when expe- 
riment proves that urea in transitu is partly converted into nitric acid. Whether 
nitric acid is thus made to appear in the urine in any diseases, is a question of great 
interest. 
The conclusions I come to from my experiments are, — 
1st. That the action of oxygen takes place in the body, not only on hydrogen, 
carbon, sulphur and phosphorus, but also on nitrogen. 
2ndly. That in all cases of combustion, out of the body and in the body, if ammonia 
is present, it is converted partly into nitric acid. 
3rdly. That the nitrogen of the air is not indifferent in ordinary cases of combus- 
tion, but that it gives rise to minute quantities of nitric acid. 
The general result is, that the production of nitric acid from ammonia in the body 
adds another to the many instances of the action of oxygen in Man. 
In the formation of water and carbonic acid, oxygenation has long been recognized 
as the great cause of the animal heat. 
In the Philosophical Transactions for 1846 and 1850, I have endeavoured to show 
that the excretion of phosphoric and sulphuric acids in excess may be the means of 
ascertaining in what tissue the most energetic action of oxygen is taking place. 
In the present paper, it appears that the detection of nitric acid in the urine may 
lead to the conclusion, that the blood is being freed from ammonia, or from substances 
closely related to it, as urea, or possibly caffein and other alkaloids. 
The same action then takes place in the fluids of the body as occurs in wells and 
streams when tainted with sulphuretted hydrogen and ammoniacal animal matter. In 
the body, as well as out of it, from these substances, sulphuric and nitric acids are 
produced by the purifying action of the oxygen of the atmosphere. 
APPENDIX. 
On Nitric Acid in Rain-water. 
During January, on different wet days, rain-water was collected in London and 
decreasing quantities were evaporated with perfectly pure carbonate of potash ; and 
I found that nitric acid was always present and could be detected even in a pint of 
rain-water by the starch test. 
Moreover, in rain-water collected about the same time at Kingston in Surrey ; at 
Melbury in Dorsetshire, many miles from any town ; and near Clonakilty in the 
county of Cork, when a south-west wind was blowing, I found distinct evidence of 
nitric acid. 
