CONDENSATION OF NITROGEN. 
41 
bably first formed, out of this nitric acid, and from the latter, 
under the influence of the hydrogen liberated at the for- 
mation of humous substances, ammonia, which remains in 
combination with the humic acid. The possibility of a con- 
densation of the free nitrogen of the atmosphere to ammonia 
results from the following experiments : — 
When clean, fresh iron filings are placed in a flask moist- 
ened with a little water, and red litmus-paper suspended in 
it, the paper in the closed flask becomes in a few days blue.* 
On the 10th of May some freshly ignited powdered char- 
coal was conveyed into a glass flask with hot distilled water, 
so that about seven-eighths of the flask remained filled with 
atmospheric air. On the 1st of August the charcoal was 
examined; it was distilled with pure caustic potash, and 
gave perceptible traces of ammonia. The water with 
which the charcoal was washed remained perfectly color- 
less. 
Humic acid, prepared from sugar, was moistened with a 
little water (both free from ammonia,) and left for six 
months in a closed flask ; upon being then treated with pot- 
ash, the substance disengaged a considerable quantity of 
ammonia. 
Well-ignited charcoal was conveyed, on the 10th of May, 
while hot, into a glass flask with ground stopper, sprinkled 
with potato-starch and moistened with water. It was ex- 
amined on the 1st of August ; a disengagement of gas had 
commenced, for on touching the stopper it was thrown out 
of the neck. The mixture had a very distinct smell of 
cheese. A portion, distilled with potash, gave abundant 
proofs of ammonia, far more than the charcoal alone. 
Washed with water, the liquid passed colorless through the 
filter. 
Gum arabic, mixed in the same manner with charcoal, 
♦According to Berzelius this res-ults from the decomposition of the color- 
ing substance, azolitmine, when kept in a moist state. Report for 1844, p. 
53.— Ed. Chem. Gaz. 
4* 
