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XI. On Spontaneous Nitrification. By C. F. Schoenbein, Professor of Chemistry in 
the University of Bale. Communicated by Michael Faraday, Esq., F.R.S., 8 fc . 
Received November 6, 1845, — Read February 12, 1846. 
A. FACT not. yet well understood is the spontaneous formation of nitric acid, or 
rather nitrates which takes place when azotic organic matters putrify in contact with 
strong bases and atmospheric air. Some chemists hold the opinion that under the 
circumstances mentioned, nitric acid is formed out of the nitrogen of the organic 
substances and atmospheric oxygen, both elements being determined to unite with 
one another by what is called the predisposing affinity of the bases for nitric acid. 
Others maintain that the said acid originates entirely from the oxygen and nitrogen 
of the atmosphere, and suppose that these elements are by a sort of capillary action 
brought into such a condensed state as to combine into nitric acid, under the addi- 
tional influence of the predisposing affinity of the bases for that acid. 
According to the notions prevailing at present nitric acid comes from ammonia, 
which is supposed to be acted upon by the oxygen of the air, i. e. dehydrogenized, 
and its nitrogen united to oxygen. The only thing sure is, that we know very little 
about spontaneous nitrification. 
Considering the theoretical interest connected with the obscure phenomenon in 
question, it must appear very desirable that novel facts should be ascertained calcu- 
lated to throw light upon, and lead to the true insight into, the cause of spontaneous 
nitrification. The observations I am about to state will perhaps contribute a little 
to obtain that end. 
Some years ago I ascertained the fact, that a solution of potash, sufficiently long- 
treated with air ozonized (by the means of phosphorus), yields a liquid which, being 
over-saturated with sulphuric acid and heated, causes a brownish coloration round 
a crystal of sulphate of iron, and has the power of destroying indigo*. From that 
fact I inferred at the time that the reactions indicated are due to the presence of a 
nitrate. 
Some time after I found out that the acid liquid called phosphatic acid, produced 
during the action of phosphorus upon moist atmospheric air, enjoys likewise the 
property of destroying indigo. If that acid is perceptibly coloured by a solution of 
indigo and left to itself, after a few hours it will have become colourless, or if the 
same acid be heated, its colour will be discharged within a few minutes. 
Phosphatic acid, some iodide of potassium being dissolved in it, assumes a yellowish 
* See Les Archives de l’Electricite, No. 15, p. 417. 
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