. THE SOURCES OF THE NITROGEN OF VEGETATION, ETC. 499 
Surres 1.—Experiments on the decomposition of nitrogenous organic matter, 
made in 1857. 
Wheat-meal, Barley-meal, and Bean-meal were the nitrogenous organic substances 
submitted to decomposition. A quantity of each of these was mixed respectively 
with burnt soil and with pumice, making in all six separate experiments. About 100 
grammes of soil, or about 60 grammes of pumice, were used—these quantities, together 
with the meal, filling the bottles B to the depth of about 2 inches. Sufficient water 
was added to bring the mixture into an agglutinated condition. The materials being so 
prepared, the apparatus was put together according to the arrangement above described. 
The six sets were then placed in a light room before a large window, so that, during the 
middle of the day, the sun shone directly upon them. 
The experiments commenced on June 10, and terminated on October 8, 1857. Several 
litres of air were drawn through each apparatus daily, by applying the mouth to the 
tube E. After the first day the gas possessed a more or less disagreeable taste, and the 
odour of decomposing organic matter. 
The following statement of the condition of the several mixtures, at the termination 
of the experiment, is condensed from the notes then made :— 
1. Wheat-meal and ignited Pumice—The meal slightly mouldy; the odour that of 
decomposing organic matter; quite moist, so that the particles of pumice adhered 
together. 
2. Wheat-meal and ignited Soil_—A slight mouldy coating on the surface ; odour like 
that of No. 1; the mass moist, but not sufficiently so for the particles of soil to aggluti- 
nate. 
3. Bariey-meal and ignited Pumice.—No mouldy coating on the surface ; odour similar 
to that of the wheat but more intense, and sour, much like that of fermenting malt ; 
the mass wet and clammy. 
4, Barley-meal and ignited Soil.No mouldy coating on the surface; odour like that 
of barley No. 3; sufficiently moist to agglutinate. 
5. Bean-meal and ignited Pumice.—A little mould upon the surface, but not quite so 
much as with the wheat and soil (No. 2); odour very disagreeable and putrescent; the 
mass wet and clammy. 
6. Bean-meal and ignited Soil. Very similar to the bean-meal and ignited pumice 
(No 5), but a little more wet and pasty. 
In every case, carbonic acid was evolved on the addition of oxalic acid, preparatory to 
evaporating to dryness. The evolution was the greatest from the bean-meal with soil. 
A known proportion, about one-half, of each dried mass, was burnt with soda-lime, 
and the Nitrogen capable of estimation in that way determined. The remainder was 
reserved for the determination of nitrates, provided any were present. On examination, 
however, no nitric acid was detected. To put the validity of the qualitative test for 
nitric acid beyond doubt, 0-001 gramme of nitric acid was added to the portion of sub- 
stance which had been already exhausted to test for nitric acid, and had yielded a nega- 
