was then poured in till it reached the height to 

 which the mercury had risen, which, therefore, was 

 the bulk of residual air : and afterwards to fill the 

 jar completely, it required 7.6 cubic inches more, 

 which was the bulk of air that had disappeared. 

 These quantities together amount only to 33.0, and 

 the 3.5 required to make up the 36.5 cubic inches 

 of air which the jar was capable of containing, must, 

 therefore, be allowed as the space occupied by the 

 several substances used in the experiment, which 

 reduces the volume of air actually employed to 33.O 

 cubic inches, of which a portion equal to 7.6 had 

 disappeared. The barometer, at the end of the ex- 

 periment, was, as already stated, 29.75, and the 

 thermometer 68. Hence, therefore, to make the 

 necessary reductions, we have '' 4 2 *;f' 75 25.8784, 



2 

 6 ' 5 



but ' 4 = .34826 and 25.8784 .34826 = 



25.53014, the corrected volume of air at the close 

 of the experiment. But atmospheric air contains 



O'> I 



^zz^-^of oxygen gas, and 33 25.53014=7.46986 



and '' 4 ^ R - ~ ^jr t Or if we compare the diminution 

 which the air suffered, with the quantity of oxygen 

 gas which it originally contained, we have 100 : 22 

 : : 33 : 7.26, which comes near to 7.46, the esti- 

 mated amount of the diminution that actually took 

 place. In a second experiment, conducted in a si- 

 milar manner, the loss of bulk which the air suffer- 

 ed, after the necessary reductions were made, was 

 -~. From these facts it is inferred, that the loss of 

 bulk, which a given volume of air suffers in vegeta- 

 tion, corresponds very nearly with the proportion of 

 oxygen gas which that air contained : and if this 



