186 Scientific Proceedings, Royal Dublin Society. 
over fallow land, and land clothed with vegetation, gave the 
following results :— 
0.2 Metres above— 
; Difference. 
Fallow Cl 
| Teewaly over. 
ees sch Soe eee meee ee teh 7 
Mean of 4 determinations in 1880, ; 4 B/D) 3°45 0:27 
om) 99 oe) 99 4°43 3°88 0°5d 
2.0 Metres above— 
Difference. 
Bellow | Clover. 
Mean of 4 determinations in 1881, : : 324 | 3:06 0-18 
” oe) ” 9 3°82 3 60 0:22 
| ERTS ae ale 
One would naturally expect that forest air, especially in summer, 
when the trees are in full vegetation, would contain less carbonic 
anhydride than the air outside the forest, but Hbermayer, who 
made a very complete investigation on this point during 1883-1884, 
found that this was not the case, at all events as regards the air 
near the surface (14 metres from ground level). 
Rejecting the results obtained by the ordinary Pettenkofer 
process, which he considered were too high,’ and taking only . 
those obtained by the aspiration method, he found as a mean of 
eighty-four experiments on the air of Bavarian forests of different 
descriptions of wood, of different ages, &c., 3°29 of carbonic 
anhydride in 10,000 volumes of air, which he contrasts with the 
amount found by other observers in various parts of the world in 
ordinary air, and with those obtained by himself on the Bavarian 
plains (Hochebene), (3°20—mean of 19 determinations), and on the 
Bavarian mountains (3°16-mean of 9 determinations), from which 
he concludes that on the whole the amount in forest air is not 
different from that in ordinary air. 
1 After a preliminary inquiry with Swappach in 1877-1878. 2 See p. 225. 
