ELISHA MITCHELL SCIENTIFIC SOCIETY. 27 



and decay. That such an equilibrium exists is not 

 above question. The changes in the amount of carbon 

 dioxide would be so slig-ht from 3xar to yQ3.r, however, 

 and accurate anal3^tical methods are so recent an ac- 

 quisition that there is no experimental proof to settle 

 the question. Still, it is clear that if the present propor- 

 tion of carbon dioxide in the atmosphere is dependent 

 upon a sort of equilibrium between, in the main, the 

 formation of carbon dioxide by combustion and its re- 

 moval by the g-rowth of plants, this balance cannot be 

 kept up if we enormously increase combustion, at the 

 same time cutting* down our forests and so limiting- 

 plant g-rowth. The removal of this prejudicial bod 3^ 

 from the air by the formation of earth3^ carbonates is 

 too slow to materially affect the result. This means 

 then that the total amount of carbon dioxide in the air 

 must increase and of course its ratio to the ox3'g-enalso. 

 It is well known that this ratio does not bear much 

 increase before the dang-er line is reached. 



One of the calculations of the present total amount 

 of carbon doxide in the air, or carbonic acid, as it is 

 commonly called, places it at some four billion tons. 

 Now taking- one of the estimates (Mr. Wister's) of the 

 consumption of coal for one hundred 3"ears, namel3% 

 840,000,000,000 tons, we find this is equivalent to 

 about 3,000 billion tons of carbon dioxide. This would 

 g-ive 30 billion tons a year, or seven and a half times 

 the present estimate of the total amount in the air. 

 This amount added to that breathed out 133^ the increas- 

 ing- population of the earth makes it manifest that, be- 

 fore the huudred years are out, we will be in the serious 

 dang-er of asphyxiation. 



Thougfh the above estimates ma3' be somewhat be- 

 3^ond the mark, and, of course, they are offered as ap- 



