44 
CONDENSATION OF NITROGEN. 
with humic acid afforded, on distillation with potash, a con- 
siderable quantity of ammonia. 
Three white beans, dried at 212°, weighed 1.465; three 
brown beans, 1.277 ; three plants of the brown beans, which 
had grown in charcoal and ash only, dried at 212°, weighed 
1.772 ; three of the white beans, which had grown in charcoal, 
ash and ulmic acid, 4.167. This experiment, therefore (and 
we shall return to it presently,) proves the nutritive power of 
the ulmic acid for the plants. The three white and the three 
brown beans were filed to a powder, and the plants of both 
treated in the same manner. The amount of ash was as fol- 
lows : — 
0.488 white beans, dried at 212°, yielded 0.023 ash. 
0.633 of the white bean plants, 0.043. 
0.403 of brown beans, 0.015. 
0.605 of the plants of the latter, 0.055. 
The amount of nitrogen, on the contrary, was — 
White beans. Nitrogen. Brown beans. Nitrogen. 
Beans 1.465 50 CbC 1.277 27 CbC 
Plants 4167 160 CbC 1.772 54 CbC 
Three white beans, therefore, in becoming plants in char- 
coal, ulmic acid and ash, had taken up more than thrice the 
amount of nitrogen ; three brown beans in charcoal exactly 
twice the quantity. 
It is a difficult matter to ascertain whether the organic con- 
stituents of the soil are absorbed as such by the plants. This 
difficulty arises principally from the circumstance of its being 
impossible to present the same quantity of nutriment to the 
plants submitted to examination ; and with too large or too 
small a quantity results are obtained between which no com- 
parison can be made. 
Several glasses of the same size were arranged side by side 
in an uninhabited room, exposed to no exhalations; some 
coarse well- washed sand was placed in the first five, and into 
all the other series of five a mixture of the same sand with 1 
per cent, of common wood-ashes ; and, moreover, in the second 
