100 
SIR J. B. LA WES AND PROFESSOR J. H. GILBERT ON THE 
it must be believed that the soil had fixed nitrogen; and he considered that, if there 
were not absolute proof, there was strong presumption, that the nitrogen of the air 
takes part in nitrification. 
In the next year, 1860, he put into one large glass balloon a mixture of rich soil 
and sand, and into another a similar mixture with cellulose in addition; each was 
moistened with distilled water, and the vessels were then closed up for 11 years. 
During this period, without cellulose rather more, and with cellulose rather less, than 
one-third of the nitrogen of the soil was nitrified; but in neither case was there any 
gain of total combined nitrogen. There was, indeed, in both cases, a slight loss of 
nitrogen indicated. Boussingault concluded that free nitrogen had not contributed 
to the formation of nitric acid.* 
The later results of Boussingault did not therefore confirm those he obtained in 
1858 and 1859 ; and in answer to one of ourselves he wrote in 1876, that he was not 
aware of any irreproachable observation which established the reality of the fixation of 
free nitrogen by the soil. He further stated his belief that neither the higher plants, 
nor mycoderms, nor fungi {champignons), fix free nitrogen. He also maintained the 
same view in conversation in 1883. 
Boussing^ult’s very distinct final conclusion against the supposition of the fixation 
of free nitrogen within the soil, by the agency of the lower organisms, notwithstanding 
his own clear recognition in 1858 and 1859 of the possibility of such an action, points 
to the necessity for still further confirmation of the evidence of others on the point 
during the last few years; for it will be remembered that whatever other sources of 
error were possible, the experiments in question were made in closed vessels, and not 
in free air, with all the risks incident to experiments so conducted; and if there may 
have been error with such an experimenter, and under such conditions, caution should 
surely be exercised in accepting very important conclusions founded on results obtained 
for the most part under less favourable conditions. 
3, General Considerations and Conclusions. 
So much for the evidence of direct experiment as to whether the higher plants, or 
Soils, by the agency either of micro-organisms or otherwise, fix the free nitrogen of the 
atmosphere. It is clear that since experimenting in free air instead of in closed 
vessels has become more general, there has been a great accumulation of evidence 
which is held to show the fixation of free nitrogen. But not only are the gains in 
* Quite recently (‘ Compt. Rend.,’ vol. 106, 1888, pp. 805 and 898) M. Schlcesing referring 
to these results says that for his part he was satisfied with this result of Boussingault, and should not 
have entered upon new experiments, had not the question been recently taken up and answered in a 
contrary sense. He then gives the results of experiments in which he submitted various soils to the 
action of air in closed vessels, supplying oxygen as it was used up. The result was that the air of the 
vessels neither lost nor gained nitrogen. There was therefore uo fixation. 
