president's address. 35 



assumed to contain gaseous matter in the same ratio, sufficient 

 is in existence to form man}'- hundred atmospheres. Carbon 

 dioxide is known to be evolved in immense quantities from 

 volcanoes and to be also extruded from the rock walls in mines, 

 from springs, from the surface soil and from innumerable caves, 

 one of the best known of which, perhaps, is the Grotta del Cane, 

 near Naples, where dogs are rendered insensible and lights 

 extinguished by the layer of gas on the floor of the cave. It 

 seems reasonable to admit that in these we have a sufficient 

 source of supply for what, though aggregating many millions of 

 tons of carbon dioxide annually, is relatively but a small quantity 

 in comparison with the amount existing in the atmosphere at 

 any one time. 



The causes of loss of carbon dioxide may be divided into 

 temporary and permanent. Of the former, absorption by the 

 waters of the ocean and fixation by living organisms may be 

 considered the most important. The great cause of permanent 

 loss will be the withdrawal of carbon dioxide through its action 

 in weathering the surface of the land, which is acting continuously 

 wherever moisture and air have access to rocks and soil. In the 

 case of the carbon dioxide taken up by the ocean, we have seen 

 that this source of loss varies in activity with the temperature 

 of the water, and that with rise in temperature the borrowed gas 

 is returned to the atmosphere By far the greater proportion of 

 the carbon taken up and tixed in the tissues of living organisms 

 is returned to the air again, for the balance of life and death 

 remains unchanged. It is true that in coal deposits great quan- 

 tities of carbon have been permanently fixed, but even the total 

 of this, on a liberal estimate, amounts to but a tiny fraction of 

 the world's stock, and in any case such fixation could but take 

 its place along with the other sources of permanent removal and 

 merely have efiect in delaying the change from one climatic state 

 to another. Tiie carbon fixed in coral, limestone and similar 

 formations aggregates a much greater proportion of the whole 

 than that locked up in coal, but as all of this is derived from the 

 fixed portion of that captured by the ocean, or in some cases by 



