THE SOURCES OF THE NITROGEN OF VEGETATION, ETC. 505 
husk is filled with fluid. On evaporation with oxalic acid, there was evolution of car- 
bonic acid, &c., as with the last; indeed it was the same with all those whieh follow. 
Wheat (c)—Meal, in Soil with 40 cub. cent. water—In this, as in all the other cases, 
owing to the water added on the Ist of July, the mass was covered to the depth of from 
i to 4 an inch with fluid. In both the above cases with Wheat, the supernatant water 
was colourless, but in this it had a dirty, muddy, yellowish colour. The mass emitted a 
foul disagreeable odour, though not so intense as that of the corresponding Barley. 
Barley (a)—Seeds, in Soil with 50 cub. cent. water—The organic matter thoroughly 
decomposed ; stems, roots, and leaves no longer distinguishable in the soil ; other con- 
ditions about as those with the corresponding Wheat a. 
Barley (6)—Seeds, in Pumice with 100 cub. cent. water—The pumice covered with a 
black coating of organic matter; supernatant water clear. The odour of the air above 
the mixture exceedingly disgusting, resembling that of decaying excrements; traces of 
sulphide of hydrogen perceptible. The form of the seeds is preserved, but the shell con- 
tains only fluid. 
Barley (c)—Meal, in Soil with 40 cub. cent. water—Supernatant water yellowish ; 
odour musty, but not very disagreeable. Decomposition so complete that traces of 
organic matter are hardly perceptible. 
Bean (a)—Seed, in Soil with 50 cub. cent. water.—The organic matter well decom- 
posed. Odour musty. 
Bean (b)—WSeeds, in Pumice with 50 cub. cent. water —Plants well decomposed ; only 
very indefinite skeletons of stems, leaves, and roots remaining. Odour musty, but not 
disagreeable. 
Bean (c)—Meal, in Soil with 40 cub. cent. water—Supernatant water slightly yellow. 
Odour musty, but not offensive. 
The last description, dated August 28, refers to the state of the respective masses just 
before being dried for analysis. After drying, any slight remains of organic matter had 
become brittle; and the substance, in every case excepting where 100 cub. cent. water 
had been added at the commencement, presented the appearance of clean soil or pumice, 
without organic matter. In the excepted cases the shell of the grain was still visible. 
If we take into consideration the amount of growth in several of the cases on April 28, 
it will be seen how great must have been the subsequent decomposition so entirely to 
get rid of the organic matter. 
It is worthy of remark, that, in a few instances, the sulphuric acid in the bottle D, 
fig. 8, Plate I., became coloured slightly brown, indicating the passage into it, through 
the oxalic acid, of some carbon-compound more complicated than carbonic acid. In the 
course of other parts of our investigation, we have observed phenomena indicative of a 
similar result; but as we have not followed up the subject, we leave it with only this 
remark as to the fact of what we have observed. 
32% 2 
