582 Le Cy LLANELLI TIN 
the ocean, which then tends to prevent the escape of the car- 
bonic acid. Low temperature is, therefore, antagonistic to 
atmospheric resupply. Mr. Tolman has attempted to ascertain 
the relative value of increased absorptive power and reduced 
partial pressure, and, though the data are insufficient for final 
conclusions, finds them about equal. The withdrawal of carbon 
dioxide from the air does not therefore call forth a proportionate 
amount of free carbonic acid from the sea. Indeed, it calls forth 
so little that the rate of atmospheric depletion is probably not 
appreciably retarded by it. 
Summation.— Before proceeding to make special application 
of the hypothesis to the recognized glacial periods it may be 
serviceable to bring together into briefer statement the fluctuat- 
ing features of atmospheric gain and loss. 
1. Of the agencies of original or permanent supply, the 
internal group have probably fluctuated in some rude proportion 
to the disruption of the crust of the earth; the external group 
are beyond tangible treatment, but for aught that appears may 
be regarded as essentially uniform. 
2. Of the agencies of permanent depletion, the conversion 
of silicates into carbonates (the chief factor) is assumed to have 
fluctuated essentially with the extension and restriction of the 
land; the formation of carbonaceous deposits fluctuated with 
the well-known conditions that presided over coal accumulation. 
The agencies of permanent supply and of permanent loss are 
both regarded as rather slow in action and as being on the whole 
mutually compensatory, and indeed as being in some degree self- 
regulative since increase of supply naturally increases consump- 
tion and reduction of supply ultimately reduces the consumption ; 
but these relations are believed to be subject to sufficient fluctu- 
ation to give a basis for pronounced climatic changes. 
The sources of temporary supply and waste are much more 
rapid in action and apparently more intense and voluminous in 
results within any brief period. 
1. The sources of temporary loss are: (a) the locking up of 
carbon dioxide in bicarbonates while in solution as their second 
