40 
In comparing these results with the following determinations 
of the carbonic acid contained in land air, it is seen that the 
air of the Irish Sea contains a much smaller proportion of 
carbonic acid than the air of the neighbouring land. The 
most extensive observations on the land air have given as 
means : — 
Observer. 
Locality. 
No. of Expts. 
Vols. in 
10,000 of , 
Th. de Saussure, 
Chambeisy, 
104 
4-15 
Boussingault, 
Paris, 
142 
3-97 
Verver, 
Groningen, 
90 
4-20 
Roscoe, 1st series, London & Manchester, 108 
3-97 
„ 2nd series, 
Manchester, 
53 
3-92 
Smith, 
ditto. 
200 
4-03 
General 
mean of land air 
4-04 
Mean of 26 expts. on sea air 
3-086 
It would also appear that no difference is discernible in the 
amount of carbonic acid in the air of day and night over the 
Irish Sea. On the other hand, from Saussure’s observations 
a decided difference may be traced between day and night air 
on the land — a conclusion subsequently confirmed by several 
experimenters. 
In noting the above mean 3 ’08, and the apparent identity 
in the amount of carbonic acid in the air of day and night 
over the sea, it should be borne in mind that July and August 
are, in general, the hottest periods of the year, (these months 
were unusually hot this year, 1865) and that, consequently, 
all the influences may be supposed at work which would tend 
to increase the relative amount of carbonic acid, and render- 
appreciable any difference in the air of night and day. 
The conclusions therefore to be drawn from these experi- 
ments are : — 
1 . That the influence of the sea in our latitudes in abstract- 
ing the carbonic acid from the atmosphere is not so great as 
the old experiments of Vogel and others would lead us to 
suppose. 
