390 Mr. E. H. Cook on Carbon Dioxkle 



amount of animal life existing on the globe, and also that 

 many of the larger species produce a greater quantity in a 

 given time, we may with a sufficiently near approach to accu- 

 racy say that from the lower animals the air receives twice as 

 much daily as from man. Hence from the whole animal 

 kingdom we derive about 4500 millions of kilogrammes. 



The amount of dioxide which the atmosphere receives from 

 decaying animal and vegetable substances is impossible to esti- 

 mate. Most of it is produced in regions far away from the 

 abode of man. That a considerable quantity is produced from 

 this source, however, is evident when we consider the vast 

 quantity of vegetable matter which year after year falls to the 

 ground and undergoes decomposition. In fact, if the estimate 

 of the amount of action exerted by plants given later on in 

 this paper is a correct one, we must conclude that a much 

 greater amount of dioxide is produced by this process than 

 has been hitherto supposed. Although it is evidently impos- 

 sible to give figures, yet, in order to arrive at a numerical 

 estimate, we may assume that the same quantity is yielded as 

 by man, viz. 1500 millions of kilogrammes daily. 



The last soui*ce whence the air receives its supply of carbon 

 is from volcanos and the fumaroles and rents in the ground 

 in volcanic districts. The amount thus supplied is enormous, 

 both active and extinct volcanos joining in increasing the 

 quantity. Considering the area occupied b}' the volcanic dis- 

 tricts, and the immense quantities of gas which are given off 

 from the craters and fumaroles, we must readily come to the 

 conclusion that from this source by far the greater part of the 

 atmospheric carbon dioxide is derived. In fact Poggendorff 

 has calculated that at least ten times as much is derived from 

 this source as from all others put together. The numbers 

 given above for the amount yielded by other sources are pro- 

 bably greater than similar numbers deduced by Poggendorff, 

 since the amount of coal used and the population have both 

 increased since his time. Instead, therefore, of taking ten 

 times, if we take five we shall perhaps approach very near to 

 the absolute amount given by Poggendorff. This will give 

 us about 40,000 million kilogrammes daily given to the atmo- 

 sphere from subterranean sources*. 



Taking the whole of these results together, we have that 

 from all sources there is daily added to the atmosphere the 



* Supposing this C0 2 produced according to the equation 

 CaC0 3 = CaO+C0 2 , 

 we -hall have daily decomposed about 00,000 million kilogrammes of 

 limestune. 



