34 
proportion of this gas contained in the atmosphere under 
varying circumstances of situation and weather. 
But hitherto, the influence which, a priori, must necessarily 
be exercised by large bodies of water on the proportion of 
carbonic acid in the atmosphere has scarcely been sufficiently 
studied. The fact that a considerable influence is exercised 
has certainly been noticed, but beyond the incomplete results 
of one or two observers, we have no numerical data from 
which to judge of the extent of this influence, and we there- 
fore know but little of the changes in the comparative 
amount of the atmospheric carbonic acid as effected by the 
waters of the ocean. 
Dr. Roscoe therefore suggested that I should undertake 
some experiments on this subject, and kindly placed the 
necessary time and apparatus at my disposal. I may here be 
allowed to express my thanks for this kindness, and for the 
advice I have received from him during the prosecution of 
these experiments. 
It appeared from the observations of Yogel on the air of 
the Baltic and of the Channel that the sea abstracts to a very 
considerable extent the carbonic acid from the atmosphere ; 
and this conclusion was apparently confirmed by the experi- 
ments of Emmet on the air over the Atlantic and at Bermuda, 
and by the determinations of Watson at Bolton, made on air 
blowing from the seaward. 
These experiments were however, for the most part, merely 
qualitative, and the circumstances under which they were 
made, together . with the inaccurate nature of the methods 
employed, render such a conclusion premature. In fact, the 
experiments of Lewy and Morren on the nature of the gases 
which sea water holds in solution at different periods of the 
day and during various seasons of the year would appear to 
show that the sea may possibly act in quite the opposite 
direction, and cause a sensible increase in the comparative 
amount of atmospheric carbonic acid. 
