HYPOTHESIS OF CAUSE OF GLACIAL PERIODS 581 
Absorption of carbonic acid.—Independently of this the ocean 
has a specific power of absorbing carbonic acid. It is important 
to note that this power of absorption is greatly affected by 
temperature, as shown by the following table of the variations 
for pure water :* 
I volume of water at o° dissolves 1.7967 volumes of carbon dioxide. 
PMs sian iS Pare ee AAO En oases : 
I hate HY On : Tenody7 a a a af 
I Ur a ipa Hised oe 1.0020 
I te a A 2 Ole ‘e 0.9014 a oe “s ec 
The precise rates of absorption for sea water are not accu- 
rately determined, and, indeed, are determinable with difficulty 
because, experimentally, they are complicated with the ‘‘loose”’ 
carbonic acid of the bicarbonates which is liable to be constantly 
freed by dissociation. The rates appear to be something less 
than those that obtain in pure water. Mr. Tolman has discussed 
this factor in his paper already referred to. 
Release of absorbed carbonic acid.—Theoretically both the 
carbon dioxide diffused through the ocean and that dissolved in 
it should be in equilibrium with that of the air. Its quantity is 
dependent upon the temperature of the ocean and upon the 
partial pressure of the carbon dioxide of the air. Whenever the 
temperature of the ocean is raised a portion of its dissolved car- 
bon dioxide is given forth. Whenever the partial pressure of 
the carbon dioxide of the air is reduced a portion of the free 
carbon dioxide in the ocean diffuses forth to reéstablish the 
equilibrium. The tendency to equilibrium is always present, 
though the constant variations of temperature and partial pres- 
sure prevent its complete realization at any particular time. If 
there were no counteracting influence the free carbon dioxide of 
the ocean would act as though it were a part of the air, and as 
the carbonic acid of the latter was consumed, that of the former 
would come forth into it. 
But with loss of atmospheric carbon dioxide there is a reduc- 
tion of temperature, and this increases the absorptive: power of 
t Treatise on Chemistry, Vol. I. ROscorE and SCHORLEMMER, Pp. 724. 
