196 Scientific Proceedings, Royal Dublin Society. 
Geneva, because it is modified by congelation and thaw (of the 
ground), which produces a diminution of the acid even when rain 
does not fall.” 
As evidence in favour of the above views De Saussure gives. - 
the following figures :— 
Debs aie || soe Date. au | 
metres. | vols. air. metres. | vols. air. 
June, 1828, . : 10 4-79 June, 1829, . ; 77 4:07 
Tok, 1 el 8 |) Gals |) tei, WS, 2 | | cae 
aL ia w July, 1829,/ .| + 52 |) Meee 
Kia, 1 A a ge |) GOL Il Ame, eos, |) te | ane 
— — — Aug., 1829, . o |} LG 3°8 
Sly WH 6 oe | BD) Ben oven PE, oe || MOA || Aang 
ee ee a Sei, 1D, 5 | A | eT 
Oct., 1828, . : 75 3°94 Oct., 1829, . : 113 3°78 
Rory UE ST al ven Anil lll Wow U2, 6 - | 188 3-39 
Dyas, UI 9 fen MN Ween, RO, s a Be 3°72 
Fittbogen and Hasselbarth were also of opinion that rain 
generally caused a decrease. 
Lewy says, as regards the air of S. America: “ During the fine 
season normal air contains always a little more both of oxygen 
and carbonic anhydride than during the rainy season.” 
vy. Fodor, at Buda-Pesth, during observations extending over 
three years (1877-1879), compared the amount of atmospheric 
carbonic anhydride on days before rain with that on the days 
when rain fell, with the following results :— 
Mean vol. CO2 in 10,000 of air on— 
Days before rain. Days on which rain fell. 
1877, Hy (hie TiC sev. a phi ade Ld 
1878, 4 : 0°86 ; 6 3°03 
1879, : : 3°68 5 : 3°60 
Thus confirming the statement that rain causes a diminution. 
