214 Scientific Proceedings, Royal Dublin Society. 
yma e dha IDE ils 
On Grounp AIR AND ITS RELATIONS TO ATMOSPHERIC CARBONIC 
ANHYDRIDE. 
As y. Fodor, Wollny, and others have expressed very decided opinions 
as regards the 7dle which ground air plays in influencing the amount 
of atmospheric carbonic anhydride, it may not be out of place to givea 
short veswmé of the facts which have been ascertained as to the nature 
of ground air and the changes which occur in its composition, much of 
which we have taken from v. Fodor’s work on * Air, Soil, and Water.’”! 
The first observers to investigate ground air were, we believe, Boussin- 
gault and Levy, in 1852, who aspirated air from the soil at depths of 
0-3 and 0:4 metres, and found that it was rich in carbonic anhydride, 
but, on the contrary, poor in oxygen. Pettenkofer made a series of 
experiments, in 1857, with air aspirated from different depths of the soil, 
with the object of tracing the processes of decay there occurring, at 
least as regards the nature of the resulting gaseous substances. For 
this purpose a hole was dug, in the courtyard of the Physiological 
Institute at Munich, and five narrow lead tubes were inserted at depths 
of 4, 38, 24, 14, and 2 metres respectively, and the soil then carefully 
replaced. The other ends of the tubes passed into the Laboratory, and 
the gases present in the soil were obtained by slow aspiration. 
A similar method of investigation was pursued by Fleck, v. Fodor, 
and later observers. 
The general conclusions arrived at regarding the nature of ground 
air appear to be somewhat as follows :— 
(1) Ground air results from atmospheric air which has diffused 
into the soil and has there suffered change—chiefly loss of oxygen and 
considerable gain in carbonic anhydride. The sum, however, of these 
two is not very different from the original proportion of oxygen, but 
usually exceeds it by 2-3 per cent. by volume, showing that not only 
does a part of the oxygen become replaced by carbonic anhydride 
owing to oxidation of organic matter, but that there is also a definite 
evolution of carbonic anhydride from the soil, which is, no doubt, 
largely due to the operations of the micro-organisms concerned in 
ly. Fodor, ‘‘ Luft, Boden, u. Wasser’’: Brunswick, 1881. 
