338 ATMOSPHERIC SUPPLY OF MANURING MATTER. 
powerful elements of the atmosphere and its aqueous vapour, 
namely, oxygen, hydrogen, carbon, and nitrogen. He de- 
scribed the recent experiments of M. Boussingault, and also 
those of M. Ville (splendidly illustrated in a work presented 
to the Society by the French government), referring to the 
views on scientific principles of agriculture just published by 
Professor Liebig, the deductions of Mr. Pusey, the elaborate 
researches of Mr. Lawes, and the experiments of M. Barral. 
He alluded to the amount of ammonia in rain-water, dew, 
and fogs, and to the insufficiency of the methods hitherto 
employed for ascertaining the proportion of nitric acid in the 
air. He called attention to the large amount of ammonia 
constantly taken up by the soil, and washing into the land by 
rain ; and to the great importance, consequently, of exposing 
the soil in such a manner to atmospheric influence as may 
best tend to this ammoniacal absorption. Fallowing of land, 
he remarked, had given way to rotation of crops ; but that 
there was no such thing as a simple resting as fallowing 
was supposed to imply in this case, for an alteration of the 
soil under the influence of oxygen was constantly going on. 
Every interval even, between one crop and another, was in 
reality a fallow. Land should be laid up as lightly as possi- 
ble, for the purpose of its aeration. The working of land, 
with a view to this abundant aeration, was one important 
means of improvement. He regarded it as indispensable to the 
full development of the powers of the soil that steam-power 
should be brought to bear effectively upon its cultivation. 
The amazing bulk of ammonia locked up in the land itself, 
could not be taken up by plants, and would, therefore, remain 
in a form unavailable for vegetation, unless the management 
of soil tended to release such manuring matter, and bring it 
within the reach of the roots. He had calculated, from data 
furnished by some rich loamy land of tertiary drift, that the 
soil within available depths contained ammonia at the rate of 
one ton (equal to six tons of guano) per acre. This was a 
stock of wealth which would repay the most active measures 
being taken for its release and distribution. He then passed 
on to the subject of green manuring, and to that of draining, 
and the importance of a free aeration of the soil, and increased 
absorption of ammonia, after the water had been duly car- 
ried off. 
In the discussion which followed, the Rev. L. Vernon 
Harcourt referred to the manner in which certain fungi ab- 
sorbed nitrogen and the phosphates during their growth, 
and yielded ammonia and phosphates to the soil on their 
death and decomposition. Professor Way explained the 
