270 Prof. S. Arrhenius on the Influence of Carbonic Acid 



same degree of exactness ; but it is evident that the numbers 

 that might express this quantity ought to be of the same 

 order of magnitude, so that the carbon in the air can neither 

 be conceived of as very great nor as very little, in compa- 

 rison with the quantity of carbon occurring in organisms. 

 With regard to the great rapidity with which the transform- 

 ation in organic nature proceeds, the disposable quantity of 

 carbonic acid is not so excessive that changes caused by 

 climatological or other reasons in the velocity and value of 

 that transformation might be not able to cause displacements 

 of the equilibrium. 



" The following calculation is also very instructive for the 

 appreciation of the relation between the quantity of carbonic 

 acid in the air and the quantities that are transformed. 

 The world's present production of coal reaches in round 

 numbers 500 millions of tons per annum, or 1 ton per km. 2 

 of the earth's surface. Transformed into carbonic acid, this 

 quantity would correspond to about a thousandth part of 

 the carbonic acid in the atmosphere. It represents a layer of 

 limestone of 0'003 millim. thickness over the whole globe, 

 or 1*5 km. 3 in cubic measure. This quantity of carbonic 

 acid, which is supplied to the atmosphere chiefly by modern 

 industry, may be regarded as completely compensating the 

 quantity of carbonic acid that is consumed in the formation 

 of limestone (or other mineral carbonates) by the weathering 

 or decomposition of silicates. From the determination of the 

 amounts of dissolved substances, especially carbonates, in a 

 number of rivers in different countries and climates, and of 

 the quantity of water flowing in these rivers and of their 

 drainage-surface compared with the land-surface of the globe, 

 it is estimated that the quantities of dissolved carbonates that 

 are supplied to the ocean in the course of a year reach at 

 most the bulk of 3 km. 3 As it is also proved that the 

 rivers the drainage regions of which consist of silicates 

 convey very unimportant quantities of carbonates compared 

 with those that flow through limestone regions, it is per- 

 missible to draw the conclusion, which is also strengthened 

 by other reasons, that only an insignificant part of these 3 km. 3 

 of carbonates is formed directly by decomposition of silicates. 

 In other words, only an unimportant part of this quantity of 

 carbonate of lime can be derived from the process of wea- 

 thering in a year. Even though the number given were on 

 account of inexact or uncertain assumptions erroneous to the 

 extent of 50 per cent, or more, the comparison instituted is of 

 very great interest, as it proves that the most important of 

 all the processes by means of which carbonic acid has been 



