9-52. The subject
created so much interest at the time, that a committee of the French
Academy--consisting of Dumas, Regnault, Peligot, Chevreul, and
Decaisne--were appointed to investigate Ville's experiments. The result
of the investigation of the Commission was to confirm Ville's
experiments. It is a significant fact, however, that the plant
experimented with by the Commission was _cress--a non-leguminous
plant_. It has been commonly assumed that the results of recent
experiments have confirmed Ville's experiments. It is only proper to
point out that this is not a necessary inference. The assimilation of
free nitrogen by the _leguminosae_, so far as modern research has
revealed, only takes place under the influence of micro-organic life.
Ville's experiments, however, were supposed to be conducted under
_sterilised_ conditions.

In the meantime the results of Boussingault's second series of
experiments, carried out between the years 1851 and 1855, were
published, and confirmed his earlier experiments.

The results of a large number of experiments subsequently carried out
were in support of Boussingault's conclusions. Among them may be
mentioned Mene, Harting, Gunning, Lawes, Gilbert and Pugh, Roy,
Petzholdt, and Bretschneider.

Such an amount of overwhelming evidence might naturally have been
regarded as conclusively proving that the free nitrogen of the air is
not an available source of nitrogen to the plant. The question, however,
was not decided. In 1876 Berthelot reopened it. From experiments he had
carried out, he concluded that free nitrogen was fixed by various
organic compounds, under the influence of silent electric discharges. In
1885 he carried out further experiments, from which he concluded that
argillaceous soils had the power of fixing the free nitrogen of the
atmosphere. This they effected, he was of opinion, through the agency of
micro-organisms. Schloesing has recently shown that this fixation of
free nitrogen by soils is extremely doubtful.[26] The gain of nitrogen
observed under such conditions can be explained by the absorption by the
soil of combined nitrogen--viz., ammonia--from the air.

Berthelot's early experiments in 1876 had the effect of stimulating a
number of other experiments, with the result that we now possess the
solution of this long-debated and most important problem.

The names of the better known investigators on this subject, in addition
to Berthelot's, are those of Hellri