THE SOURCES OF THE NITROGEN OF VEGETATION, ETC. 449 
came from the atmosphere, might be partly due to Nitrate of Ammonia produced by 
electrical action and brought down by rain. 
2. M. BoussincatLr’s experiments in 1851, 1852, and 1853, in which the plants were 
confined in limited volumes of air*. 
BovssinGavLt resumed the subject of the sources of the Nitrogen of vegetation in 
1851. His object was, apparently, to settle more definitely, whether plants assimilated 
Nitrogen from any other source than the combined forms of it. 
In his experiments in 1851 and.1852, Bovussineavt confined his experimental plants 
under a glass shade of about 35 litres capacity, which shut off the free access of external 
air by resting in a lute of sulphuric acid. Tubes passed under the shade for the supply 
of carbonic acid, and water, as they might be needed. Pumice-stone, coarsely powdered, 
washed, ignited, and cooled over sulphuric acid, served as soil. To this, at the com- 
mencement, some of the ash from farm-yard manure, and also from seed of the kind to 
be sown, was added. 
In 1851, a Haricot was grown under these conditions, the seed of which, when sown, 
was estimated to contain 0:0349 gramme of Nitrogen. After two months of growth, 
flowers being formed, the dry substance of the plant was more than double that of the 
seed sown; and the total products yielded only 0:0340 gramme of Nitrogen. There 
was, therefore, apparently a slight loss of Nitrogen, which amounted, however, to less 
than a milligramme. In 1852, two Haricots, sown respectively in separate pots, con- 
tained, together, 0-0455 gramme Nitrogen. ‘They were each allowed to grow for three 
months, during which time the dry substance was nearly doubled; and in one instance 
open flowers were formed. The products of both experiments taken together yielded 
to analysis only 0°0415 gramme of Nitrogen. ‘There was an apparent loss, therefore, in 
the two experiments, of 4 milligrammes of Nitrogen. It is seen, then, that in these new 
experiments with Leguminous plants, in which the free circulation of atmospheric air 
was not permitted, there was not the apparent gain of Nitrogen that had been met with 
in BoussINGAULT’s early experiments (in 1837 and 1838), in which free access of air into 
the enclosing apparatus was allowed. 
In 1851, ten seeds of Oats, and in 1852 four, were experimented upon in a similar 
manner. In both cases there was an apparent very slight loss of Nitrogen. In the first 
case the Oats vegetated for two months, and in the second for 2} months; and in the 
latter, the plant arrived at the point of shooting forth the ear. 
In 1853, the apparatus adopted by BoussInGavLt consisted of a large globe, or carboy, 
of white glass, having a capacity of 70 or 80 litres. At the bottom of this vessel, a 
matrix of pumice-stone (or burnt brick) and ashes, prepared as in the last series, was 
placed to serve as soil. This was watered with distilled water, and then the seeds were 
sown. The neck of the vessel was then closed with a cork, through a perforation in 
which, a flask of carbonic acid was inverted, whose aperture, opening into the globe, was 
* Ann. de Chim. et de Phys. sér. 3. tome xli. 1854. 
3 Q2 
