on the Absorption of Air by Water. 177 



100 volumes of the air thus absorbed would consist of, 

 53*57 volumes oxygen, 

 46-43 volumes azotic gas, 



100-00 

 But, it has been shewn in the first part of this paper, that 

 the air extricated by boiling from the water of the Clyde 

 was composed of, 



29*1 volumes oxygen, 

 70*9 volumes azotic gas. 



100-0 

 It follows from this, that the air extricated from water 

 by boiling differs essentially in its composition from the air 

 absorbed by water; the quantity of oxygen in it being 

 very much diminished. 



Let us suppose that water has absorbed a hundred 

 volumes of air. They will consist, as appears from the 

 preceding statement, of, 



46*43 volumes of azotic gas, 

 53*57 volumes of oxygen. 

 But, when these 100 volumes are extricated from water 

 by boiling, they are reduced to 64-02 volumes, which con- 

 sist of, 



45*39 volumes of azotic gas, 

 18*63 volumes of oxygen. 

 Two- thirds of the original oxygen gas absorbed by the 

 water disappear, and only one-third remains. Doubtless 

 this portion of oxygen which disappears is employed in the 

 respiration of fishes, (if such an expression may be per- 

 mitted,) and for various other important purposes of which 

 we are at present ignorant. 



If any reliance can be placed in these statements, it will 

 follow that the difference between the absorbability of 

 oxygen and azotic gas by water, is much greater than has 

 hitherto been supposed. Oxygen must be about three 

 times as absorbable by water as azotic gas. 



If we compare the quantity and constitution of the air 

 extricated from water by boiling, with the constitution of 

 the air absorbed by newly boiled water, we shall find that 

 100 volumes of water absorb, 



VOL. IV. N 



