178 Scientific Proceedings, Royal Dublin Society. 
large freshwater surfaces. The following table (from which large 
cities have been purposely excluded) will show this :— 
Near Sea or Lake. | Inland. 
= s MB es ai 
frie) ale ine 
| | COs in CO, in 
Observer. Locality. BebAce Observer. Locality. be AGE 
(mean). (mean). 
| 
| 
De Saussure, . Lakeof Geneva, 4°39 || De Saussure, .| Chambeisy, . | 4°60 
Reiset, . . | Dieppe, =) 2396) |) Rislers . | Caléves, . | 3°08 
Schulze, . . Rostock, _ 292 | Henneberg, . | Weende, 5 |) B20 
Thorpe, . . | Atlantic, . | 2°95 || A. Smith, . | Scotland 3°36 
| (country), . 
| Claesson, > || Ibpragl, = | 2°79) ||| Warsky., > |) Malo, 6 . | 38°48 
| | | Thorpe, . : | Rae, o . | 3°28 
Dragendorff, . Dorpat, . | 2°66 || Fittbogen and | Dahme, . | 3°34 
| Hasselbarth, ; 
Some exceptions may be found to this rule, but they are not 
numerous. Thus Macagno, as the mean of his determinations at 
Palermo (sea side), found 3°60, while against this figure where 
excess of carbonic anhydride appears, we have that of Petermann 
and Graftiau at Gembloux (inland), viz. 2:94, and of Mintz and 
Aubin for the Plain of Vincennes (inland) 2°84—quantities even 
lower than those found at some of the seaside localities. Con- 
sidering that the chief sources of evolution of carbonic anhydride 
are confined to land surfaces, it is not at all surprising to find 
that asa rule a slight excess of the gas appears in the air over 
them, and in this connection it may be mentioned that Spring 
and Roland attribute the high figure at Liége (3°35) as partly due 
to evolution of carbonic anhydride from the ground, the soil there 
overlying coal strata, and emitting large quantities of that gas. 
According to Mintz and Aubin, another effect of locality is to 
be found in the slightly larger amount of carbonic anhydride in 
the air of the northern hemisphere compared with that of the 
southern. The figures they give for these two, as the general mean, 
being 2°82 and 2°72 respectively ; and they attribute the difference 
to the fact that the larger water surfaces of the southern hemis- 
phere are cooler than those of the northern, where land surface pre- 
dominates ; hence, according to Schleesing’s theory, the pressure of 
