CONDENSATION OP NITROGEN. 
43 
manner. All vegetable acids, and many of the indifferent 
substances, afford mould plants in larger or smaller quantity. 
Starch, above all, deserves attention in this respect. Arrow- 
root starch, preserved in pure water in a closed flask with air, 
very soon becomes turbid and opake, and forms a white pre- 
cipitate. Mulder never observed during two months and a 
half mould form at the top, but in quantity in the mass itself, 
and then likewise on the surface. According to De Saussure, 
there originates from starch which has been exposed to the air 
or preserved in some bottles with air, after a few months, a 
mixture of sugar, gum, &c., and what in the present case de- 
serves especial attention, a substance which he calls ligneux 
amylace. This ligneux amylace is cellulose combined with a 
little proteine, that is, a mould plant. De Saussure found 
from 4.4 to 10.53 per cent, in the starch employed. Ligneux 
amylace, or mould plants, which afforded very considerable 
traces of ammonia, were likewise obtained from potato-flour 
that had been preserved in a close flask with pure water and 
pure atmospheric air for two months. 
The influence of other bodies on the condensation of nitro- 
gen to ammonia in the soil is of great importance. The nas- 
cent hydrogen which is set free from the decomposed organic 
substances binds the nitrogen of the atmosphere, just as iron 
filings and water form ammonia with the nitrogen of the at- 
mosphere. A mixture of powdered charcoal with one-hun- 
dredth wood ashes was placed in two glass vessels, and ulmic 
acid, prepared from sugar, conveyed into one ; both were ex- 
posed to an atmosphere free from ammonia. Brown beans 
were placed in the first, and white beans in the other ; they 
were then sprinkled with distilled water, perfectly free from 
ammonia, and kept moist. The development and growth of 
the plants were extremely different in the two vessels ; those 
in the ulmic acid vegetated powerfully, the others remained 
far behind. After twenty-four days they were taken out, the 
roots carefully freed from the charcoal with water, then dried 
and weighed. The residuary charcoal and the charcoal mixed 
